CME Wrist Essentials: The Diagnosis and Management of Scapholunate Ligament Injuries Harvey Chim, M.D. Steven L. Moran, M.D. Cleveland, Ohio; and Rochester, Minn.
Learning Objectives: After studying this article, the participant should be able to: 1. Understand the pathophysiology of a scapholunate injury. 2. Understand how to diagnose scapholunate injuries 3. Formulate and carry out a surgical plan for patients with a scapholunate injury. Summary: Scapholunate ligament instability is the most common form of carpal instability. Untreated scapholunate injuries can lead to a predictable pattern of wrist arthritis. Early forms of scapholunate ligament instability can be missed, and clinical detection relies on an educated observer. This article covers the basic anatomy and biomechanics of the wrist, and reviews in detail scapholunate ligament injury. This article also reviews and discusses the current relevant topics and issues surrounding scapholunate ligament injury. (Plast. Reconstr. Surg. 134: 312e, 2014.)
T
he wrist is subject to a variety of axial and rotational loads, which can result in a variety of ligamentous injuries. This article covers the basic anatomy and biomechanics of the wrist, and reviews in detail one of the most common ligament injuries seen following wrist trauma, the scapholunate ligament injury.
ANATOMY AND BIOMECHANICS The wrist joint encompasses the distal radius and ulna, the proximal carpal row, the distal carpal row, and the bases of the five metacarpal bones. The wrist consists of four major joints: the radiocarpal, the midcarpal, the carpometacarpal, and the distal radioulnar joints. Most wrist abnormality is encountered within the radiocarpal and distal radioulnar joints. The distal carpal row is made up of the trapezium, trapezoid, capitate, and hamate. The intercarpal ligaments between the bones of the distal carpal row are stout and allow for little motion between the bones; thus, for biomechanical purposes, we can assume the distal carpal row behaves like a single bone. In contrast, the bones of the proximal carpal row, made up of the scaphoid, lunate, and triquetrum, have a moderate degree of intercarpal motion with wrist movement. Because there are no muscles that attach to the From Case Western Reserve University and the Mayo Clinic. Received for publication April 29, 2013; accepted August 14, 2013. Copyright © 2014 by the American Society of Plastic Surgeons DOI: 10.1097/PRS.0000000000000423
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proximal carpal row, the motion of these bones is in passive response to the motion of the distal carpal row and radius; thus, the proximal carpal row is termed the intercalated segment of the wrist, as it is not capable of independent motion. The ligaments that stabilize wrist motion can be divided into two general categories: those that run between the bones, termed interosseous ligaments; and those that make up the wrist capsule, running from the radius and ulna to the carpal bones, termed the extrinsic wrist ligaments. The interosseous ligaments include the scapholunate and lunotriquetral interosseous ligaments (Fig. 1). These two ligaments are the major stabilizers of the proximal carpal row and carpus.1,2 The majority of the extrinsic wrist ligaments are found palmarly and serve as secondary stabilizers of carpal motion (Fig. 2). The palmar extrinsic ligaments form an arc-shaped configuration over the carpal bones and include the radioscaphocapitate ligament, the long radiolunate ligament, and the short radiolunate ligament. The important dorsal Related Video content is available for this article. The videos can be found under the “Related Videos” section of the full-text a rticle, or, for Ovid users, using the URL citations published in the article.
Disclosure: Neither of the authors has a financial interest in any of the products or devices mentioned in this article.
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Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 1. Intrinsic ligaments of the wrist are those ligaments that both originate and insert among the carpal bones. A palmar view of the wrist demonstrates the scapholunate (SL), lunotriquetral (LT), trapezium-trapezoid (TT), the capitotrapeziod (CT), capitohamate (CH) intrinsic, the scaphotrapeziumtrapezoid (STT), the scaphocapitate (SC), the triquetrocapitate (TC), and the triquetrohamate (TH) ligaments. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
extrinsic ligaments include the dorsal radiocarpal ligament, which is an important secondary stabilizer of scaphoid motion.2–6 For simplicity, wrist motion can be broken down into three major arcs that include radial and ulnar deviation, flexion and extension, and the “dart-thrower’s” arc. The dart-thrower’s arc involves an oblique plane moving from radial deviation and wrist extension to ulnar deviation and wrist flexion. This arc is considered to be involved in many daily activities.7–10 The distal pole of the scaphoid extends into the distal carpal row, allowing the scaphoid to function as a link between the proximal and distal carpal rows.11 During wrist radial deviation and wrist flexion, the scaphoid is pushed into flexion by the distal carpal row; as this occurs, the scaphoid pulls the lunate into flexion through the pull of the scapholunate interosseous ligament. The lunate, in turn, pulls the triquetrum into flexion through the stout attachment of the lunotriquetral interosseous ligament. During ulnar deviation and wrist extension, the distal carpal row, through the helical articulation between the hamate and
triquetrum, pushes the triquetrum into extension. The triquetrum then pulls the rest of the proximal carpal row into extension through intact lunotriquetral and scapholunate interosseous ligaments. During the dart-thrower’s arc, motion at the scaphoid and lunate is limited, and the majority of carpal motion occurs through the midcarpal joint. Because this arc of motion does not result in significant motion between the scaphoid and the lunate, it may have important implications in wrist rehabilitation following scapholunate interosseous ligament repair.7,8,12 When there is an injury to either the scapholunate interosseous ligament or lunotriquetral interosseous ligament, the bones of the proximal carpal row become unlinked and will move abnormally; this is referred to as carpal instability. Over time, this abnormal motion stretches the surrounding extrinsic ligaments, leading to further instability and radiographic abnormalities. Abnormal carpal motion leads to cartilage damage and eventual wrist arthritis.1,2,13–15 The most common form of carpal instability is scapholunate dissociation.16–18 The timeline for developing arthritis following scapholunate interosseous ligament injury is still unknown.
SCAPHOLUNATE LIGAMENT INJURY Injury to the scapholunate interosseous ligament is usually the result of a fall onto an extended wrist and may present as an isolated injury or in association with a distal radius fracture, scaphoid fracture, or perilunate dislocation. There are several chronic conditions that may also predispose to the development of an attritional tear of the scapholunate interosseous ligament, and these include Kienböck disease, rheumatoid arthritis, and pseudogout. Injury to the scapholunate interosseous ligament usually begins in the palmar component of the ligament, which is less stout than the dorsal component. The injury then progresses dorsally until a complete tear is present. Partial tears may produce only pain with activity and result in little abnormality in scaphoid motion; however, complete ruptures of the scapholunate interosseous ligament result in dissociation of the scaphoid from the lunate, preventing the scaphoid from exerting any force on the lunate. Consequently, there is an unopposed extension force exerted on the lunate by the triquetrum through the intact lunotriquetral interosseous ligament. Over time, if the scapholunate interosseous ligament is not repaired, the lunate will be pulled into a permanent position of extension. When this abnormality is noted on a
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Fig. 2. Extrinsic ligaments of the wrist include those ligaments that originate outside the carpal bones and insert onto the carpal bones. From a volar view (left), the proximal ligaments from radial to ulnar include the radioscaphocapitate (RSC), long radiolunate (LRL), short radiolunate (SRL), ulnolunate (UL), ulnocapitate (UC), and ulnotriquetral (UT). R, radius; U, ulna; RA, radial artery; AIA, anterior interosseous artery; PRU, palmar radioulnar ligament; S, scaphoid; P, pisiform; T, triquetrum; Tm, trapezium; Td, trapezoid; C, capitate; H, hamate. (Right) Illustration of the extrinsic dorsal wrist ligaments. There is only one true dorsal extrinsic ligament, the radiotriquetral ligament or dorsal radiocarpal (DRC) ligament as it is more commonly called. The scaphotriquetral ligament, also called the dorsal intercarpal (DIC) ligament, is by definition an intrinsic ligament, but is often thought of as an extrinsic ligament, as it crosses three bones. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
lateral radiograph of the wrist, it is termed a dorsal intercalated segment instability. Unopposed scaphoid flexion and lunate extension result in abnormal radiographic findings on lateral radiographs that include an increase in the scapholunate angle and radioscaphoid angle (Fig. 3). Ongoing scaphoid flexion results in dorsal subluxation of the scaphoid from the radial fossa. This leads to a progressive pattern of wrist arthritis termed scapholunate advanced collapse or scapholunate advanced collapse wrist (see Fig. 5).17,18 Ongoing lunate extension creates abnormal forces at the midcarpal joint, resulting in capitolunate arthrosis over time; in most cases, the radiolunate joint is spared significant arthritic wear despite scapholunate interosseous ligament injury. Scapholunate interosseous ligament injury can present within a spectrum of severity that is related to the status of the remaining ligament and surrounding extrinsic ligaments.19 This spectrum has been broken down into four categories of instability:
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1. Predynamic instability. This is the mildest form of scapholunate interosseous ligament injury and results from a stretched or partially torn scapholunate interosseous ligament. Patients complain of dorsal wrist pain following heavy exertion or lifting but have normal radiographs. Abnormalities within the scapholunate interosseous ligament at this stage can usually be seen only with arthroscopic examination. 2. Dynamic instability. In this stage of injury, the extrinsic wrist ligaments and portions of the scapholunate interosseous ligament may still be intact; however, abnormalities can be seen on radiographs when the wrist is loaded (e.g., in a clenched-fist radiograph) (Fig. 4) or placed into the extremes of motion under fluoroscopy. The intact secondary stabilizers of scaphoid motion are able to maintain normal carpal alignment when the wrist is not being subjected to loading conditions thus plain radiographs can appear normal.
Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 3. Scapholunate interosseous ligament injury can produce abnormalities in the position of the scaphoid and lunate bones that can be visible on anteroposterior and lateral radiographs. (Left) Anteroposterior radiograph in a patient with a static scapholunate injury, showing an increase in the distance between the scaphoid and lunate, which is referred to as scapholunate diastasis. In addition, the lateral radiograph (right) shows an increased scapholunate angle (>60 degrees). The lunate is tilted dorsally greater than 15 degrees, representing a dorsal intercalated segment instability deformity.
Fig. 4. Clenched-fist radiograph in a 52-year-old man with dynamic scapholunate instability. Notice that the right wrist displays a widened scapholunate interval compared with the left side.
3. Static scapholunate dissociation. When a complete scapholunate interosseous ligament tear occurs with attenuation or attrition of the supporting wrist ligaments, permanent misalignment will occur within the carpus and radiographic changes will be visible on resting, or static, radiographs. If such deformity is present on lateral and posterior anterior radiographs, we can diagnose the patient with static scapholunate dissociation.20 The term static here refers to the fact that radiographic abnormalities are seen in the wrist at rest and do not require
loading or some other dynamic maneuver for identification (Fig. 3). 4. Scapholunate advanced collapse arthritis. Longstanding carpal malalignment, following scapholunate interosseous ligament disruption, will result in cartilage damage and arthritis. This arthritis follows a typical progression and has been divided into three grades. The arthritic changes are visualized initially at the radial styloid, and this has been classified as scapholunate advanced collapse stage 1; arthritic changes are then seen at the radioscaphoid fossa, which is classified as
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Fig. 5. (Left) Anteroposterior radiograph in a patient with stage 2 scapholunate advanced collapse arthritis. Note the arthritic changes present at the radioscaphoid articulation. (Right) Anteroposterior radiograph in a patient with stage 3 scapholunate advanced collapse arthritis. Note the arthritic changes at the radioscaphoid fossa and at the capitolunate articulation.
scapholunate advanced collapse stage 2 (Fig. 5). In scapholunate advanced collapse stage 3, arthritic changes are seen in the midcarpal joint over the head of the capitate, as progressive scapholunate diastasis allows proximal migration of the capitate head (Fig. 5) (Reference 21, Level of Evidence: Therapeutic, IV).20,21 Although not part of the original staging system, and still considered controversial by many authors, scapholunate advanced collapse stage 4 would represent a wrist with arthritis extending throughout the midcarpal and radiocarpal joints. Diagnosis of Scapholunate Ligament Injury In acute scapholunate interosseous ligament injuries, physical findings may include swelling in the anatomical snuffbox and dorsal radiocarpal joint. Weakness and pain are associated with wrist loading activities. Patients may describe their wrist as “unstable,” often stating that the wrist feels “like it is going to give way” under loads. Chronic injuries may present with wrist pain and symptoms of carpal tunnel syndrome caused by underlying wrist synovitis. During physical examination, the scapholunate joint can be palpated directly by bringing the wrist into flexion and palpating 1 cm distal to the Lister tubercle. Tenderness in this area may indicate a tear. The scaphoid shift test, or Watson test, is a provocative maneuver that can help to diagnose scapholunate interosseous ligament injuries. The wrist is moved from ulnar to radial deviation
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with the examiner’s thumb pressing against the scaphoid tubercle. Patients with partial tears will have an increase in pain dorsally over the scapholunate articulation. An audible clunk may signify a complete tear, as the scaphoid is actively subluxed off the dorsum of the radius with radial deviation and spontaneously reduces into the radial fossa when the wrist is brought back into ulnar deviation. The contralateral wrist should be examined for comparison, as the scaphoid shift test may be falsely positive in up to one-third of individuals because of ligamentous laxity without injury. Progressive loss of grip strength with a repetitive gripping maneuver may also signify a scapholunate interosseous ligament injury.22 Plain radiographs are always obtained to evaluate for fracture or other abnormality. Evidence for a scapholunate interosseous ligament injury can be made by evaluating the posteroanterior and lateral wrist radiographs. The following are suggestive of a static scapholunate injury (Fig. 4).23 1. The Terry Thomas sign. Diastasis between the scaphoid and lunate with a gap greater than 3 mm. 2. The scaphoid ring sign. Excess projection of the distal pole from abnormal scaphoid flexion giving the appearance of a ring. 3. Disruption of the Gilula lines of the carpus. On lateral radiographs, a dorsal intercalated segment instability deformity may be visible with an increased scapholunate angle greater than 60
Volume 134, Number 2 • Scapholunate Ligament Injuries degrees (a normal scapholunate angle is approximately 45 degrees) or an increased radiolunate angle greater than 15 degrees (Fig. 4).23 If plain radiographs do not show abnormalities, magnetic resonance imaging can be used to diagnose partial or dynamic injuries. Computed tomography is not a sensitive modality for assessing ligamentous abnormality. If there are no abnormalities visible on imaging studies and the surgeon is still suspicious for a scapholunate interosseous ligament injury, one should consider wrist arthroscopy. Wrist arthroscopy is considered the criterion standard for diagnosis of wrist ligament injuries, as it allows direct inspection of the interosseous ligaments and surrounding extrinsic ligaments. Both radiocarpal and midcarpal arthroscopy should be performed to diagnose interosseous ligamentous instability; however, midcarpal arthroscopy (Fig. 6) is the key to assessing the stability of the scapholunate joint. (See Video, Supplemental Digital Content 1, which displays a video recording of radiocarpal and then midcarpal arthroscopy illustrating findings of scapholunate ligament injury, available in the “Related Videos” section of the full-text article on PRSJournal.com or, for Ovid users, at http://links.lww.com/PRS/B44.) The degree of injury can be graded arthroscopically based on the Geissler classification (Table 1).24 Treatment of Scapholunate Ligament Injury Once the diagnosis of scapholunate interosseous ligament injury has been made, there are
Video. Supplemental Digital Content 1, which displays a video recording of radiocarpal and then midcarpal arthroscopy illustrating findings of scapholunate ligament injury, is available in the “Related Videos” section of the full-text article on PRSJournal. com or, for Ovid users, at http://links.lww.com/PRS/B44.
several different treatment options based on the severity of the disease. Mildly symptomatic patients can be treated conservatively with wrist splinting and activity modification. Surgical treatment of scapholunate dissociation is dependent on the severity of the instability (i.e., predynamic, dynamic, or static), the chronicity of the injury, and the presence of any degenerative changes to the carpus. Treatment options have been summarized by Garcia-Elias et al. in recent reviews.25,26 Table 1. Geissler Arthroscopic Classification of Carpal Interosseous Ligament Tears* Grade I II
III
IV Fig. 6. Midcarpal arthroscopy as viewed through the radial midcarpal portal shows the scaphoid (S) and lunate (L) bones. A probe is within the palmar portion of the scapholunate interosseous ligament. Hemorrhage can be seen within the synovium surrounding the ligament, indicative of scapholunate interosseous ligament injury.
Description Attenuation and hemorrhage of interosseous ligament seen from radiocarpal joint, with no step-off present as seen from midcarpal joint Attenuation and hemorrhage of interosseous ligament seen from radiocarpal joint, with step-off as seen through midcarpal joint; the probe can be placed between scaphoid and lunate Incongruence or step-off is seen between the scaphoid and the lunate from both the radiocarpal and midcarpal portals; the probe can be placed and freely rotated between the scaphoid and lunate Incongruence or step-off is seen between the scaphoid and the lunate from both the radiocarpal and midcarpal portals; gross instability is noted, and the 2.7-mm arthroscope may be passed through the gap between the scaphoid and lunate
*From Geissler WB, Freeland AE, Savoie FH, McIntyre LW, Whipple TL. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg Am. 1996;78:357–365.
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Plastic and Reconstructive Surgery • August 2014 Acute Injuries In acute injuries, arthroscopy can be used to determine the extent of scapholunate interosseous ligament injury. Some studies have suggested that partial tears may be treated by percutaneous pinning of the scaphoid and lunate, thus allowing for the possibility of primary healing or fibrosis. Open repair of acute, complete scapholunate interosseous ligament tears has been shown to maintain grip strength and wrist motion and presumably halts the progression to degenerative changes and the development of a scapholunate advanced collapse wrist.23,27 Chronic Injuries Treatment options for chronic scapholunate interosseous ligament injuries are dependent on the presence of degenerative arthritis. If scapholunate advanced collapse arthritis is present, attempts at reconstruction of the scapholunate interosseous ligament are discouraged and some type of wrist salvage procedure is performed. The most common wrist salvage procedures performed for scapholunate advanced collapse arthritis are scaphoidectomy and fourcorner fusion or proximal row carpectomy. In the absence of arthritis, treatment is directed at reconstructing the scapholunate interosseous ligament; if the scapholunate interosseous ligament is not reconstructible because of the severity of the tear or attritional changes, some other means must be used to stabilize the scaphoid and restore the scapholunate relationship (Fig. 7). Several methods have been described, and these include capsulodesis procedures, tenodesis procedures, and limited intercarpal fusion. Surgical Management of Scapholunate Interosseous Ligament Injury Scapholunate Ligament Repair Direct ligament repair can be used to repair acute scapholunate interosseous ligament injuries, and can be considered in cases of chronic ligament injury if (1) there is satisfactory ligament present for repair, (2) the scaphoid and lunate are still easily reducible, and (3) there is no evidence of arthritis within the carpus. Ligament repair may be performed with the use of suture anchors, interosseous sutures, or interosseous wires. Recent reports have also described augmentation of the ligament with different types of biological tendon replacements. After repair, the joint is pinned and immobilized in a cast for 6 to 8 weeks.23,28 Open repair of acute scapholunate interosseous ligament tears has been shown to maintain adequate
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Fig. 7. Example of a chronic scapholunate interosseous ligament tear seen following exposure of the wrist joint through a dorsal approach. Kirschner wires have been placed into the scaphoid (s) and lunate (L) to aid with reduction of the bones. Primary repair of the ligament is not possible in this case, as the ligament has degenerated and would be incapable of holding a stitch.
grip strength and wrist motion with minimal progression to degenerative changes.28,29 The open technique for scapholunate interosseous ligament repair is generally performed through a dorsal midline incision. The extensor retinaculum is divided over the third dorsal compartment and the extensor pollicis longus tendon is retracted radially. Retinacular flaps are elevated from the third dorsal compartment to the second compartment radially and from the third dorsal compartment to the fifth compartment ulnarly. A ligament-sparing capsulotomy is performed (Fig. 8), as described by Berger et al., to gain access to the carpus.30 This capsulotomy is in line with the fibers of the dorsal intercarpal ligament and dorsal radiocarpal ligament; this facilitates closure and minimizes damage to the dorsal extrinsic ligaments. Care is taken to elevate a full-thickness flap that does not violate the dorsal components of the scapholunate interosseous ligament and lunotriquetral interosseous ligament. If a capsulodesis is being considered for management of scapholunate interosseous ligament injury, care should be taken to leave the dorsal capsule attached to the scaphoid waist. After surgical exposure, the carpus is evaluated. The scapholunate interosseous ligament is usually
Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 8. Scapholunate repair is usually accomplished through a dorsal approach to the wrist. A ligament-sparing capsulodesis creates a radially based flap that follows the fibers of the dorsal radioscaphotriquetral ligament and dorsal intercarpal ligament (left and center). This flap allows excellent exposure of the scapholunate joint as shown in Figure 7. The bones are then held in position with percutaneous Kirschner wires. After reduction, the primary repair or capsulodesis can be performed with the use of suture anchors. (Right) Postoperative radiograph of a woman who has undergone a scapholunate repair in conjunction with a Mayo-type dorsal capsulodesis. (Left and center, reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
torn off the scaphoid. The scapholunate relationship is reestablished with the aid of Kirschner wires, which are placed dorsally into the scaphoid and lunate to act as joysticks. The scapholunate interface is reduced and the bones are held with two or three Kirschner wires. The midcarpal joint may also be pinned for added stabilization. The scapholunate interosseous ligament is then repaired with bone anchors (Fig. 8). Kirschner wires are left for 8 to 10 weeks and patients are protected from full loading for an additional 4 to 6 weeks.28 Capsulodesis and Tenodesis When primary repair is not possible because of attrition of the scapholunate interosseous ligament, unopposed flexion of the scaphoid can be controlled with the use of capsulodesis or tenodesis procedures. Capsulodesis uses a portion of the dorsal wrist capsule to tether the scaphoid, and prevents it from flexing. A variety of capsulodesis procedures have been described (Fig. 9), but none has been shown to produce superior results (Reference 32, Level of Evidence: Therapeutic, IV).31,32 This technique is useful in conjunction with ligament repair for chronic instability or may also be used alone for cases of dynamic instability. Unfortunately, long-term outcome studies examining capsulodesis procedures have yielded mixed results in terms of wrist function and maintenance of carpal alignment.32,33
Tenodesis procedures use tendons to either tether carpal bone motion or to replace and reconstruct the scapholunate interosseous ligament. A variety of tenodesis procedures have been described. The most common form of tenodesis is the Brunelli tenodesis that uses half of the flexor carpi radialis tendon passed through a bone tunnel in the scaphoid and secured dorsally to the distal radius or lunate. The problem with all tenodesis procedures is that the elastic moduli of tendon and ligament are not equivalent. Restriction of scaphoid motion using a tendon usually requires a significant degree of tension on the tendon, which can restrict overall wrist motion (Reference 34, Level of Evidence: Therapeutic, III).25,34,35 Intercarpal Fusion In cases of chronic instability when the scapholunate malalignment is not reducible and there is not yet evidence of cartilage degeneration, limited intercarpal fusions can be performed; scaphotrapezial-trapezoidal and scaphocapitate arthrodesis have both been advocated to restrict scaphoid motion. Intercarpal fusion stabilizes the scaphoid and restores its alignment with the distal radius. Unfortunately, scaphotrapezial-trapezoidal and scaphocapitate fusions alter carpal kinematics, leading to an increased load across the radioscaphoid fossa. Over time, these fusions
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Fig. 9. Capsulodesis procedures use a portion of the dorsal wrist capsule to control scaphoid flexion. Here, one sees an example of a Mayo-type capsulodesis where a portion of the dorsal intercarpal ligament is used to tether the scaphoid in an extended position. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
Fig. 10. Anteroposterior radiograph of a patient who has undergone a proximal row carpectomy.
have been shown to result in the development of degenerative arthritis within the wrist.36–38 Surgical Management of Scapholunate Advanced Collapse Arthritis Once patients show evidence of radiocarpal arthritis, it is recommended that some type of wrist salvage procedure should be performed, as attempts to reconstruct the scapholunate interosseous ligament could still leave the patient with ongoing pain. The two most common procedures used are proximal row carpectomy (Fig. 10) and scaphoid excision and four-corner bone fusion (Fig. 11). These procedures can provide pain relief and preserve some wrist motion (Level of Evidence: Therapeutic, II).39 Proximal Row Carpectomy Removal of the scaphoid, lunate, and triquetrum with meticulous capsular repair allows the capitate to articulate with the lunate fossa of the distal radius, preserving wrist motion and removing the diseased proximal carpal bones (Fig. 10). Good long-term results at 10-year follow-up have been achieved, with total wrist motion ranging from 63 to 76 degrees and grip strength up to 91 percent of the contralateral side.40–43 Advantages include a shortened period of postoperative immobilization and no requirement for bone fusion, which is an issue of concern in smokers. The main contraindication for this procedure is
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Fig. 11. Anteroposterior radiograph of a patient who has undergone a four-corner fusion and scaphoidectomy using plate-andscrew fixation.
arthritic changes at the lunocapitate joint, which prevent creation of a stable articulation between the capitate and radiolunate fossa. Long-term radiographic changes include arthritis at the radiocapitate interface in most patients 10 years after surgery. It is not clear what impact these changes will have on longer follow-up. Four-Corner Arthrodesis This procedure involves fusion of the lunate, triquetrum, capitate, and hamate, with removal of the scaphoid (Fig. 11). The radiolunate articulation must be intact without carpal subluxation. In the largest single series of 100 patients by Ashmead et al.,44 91 percent of patients had
Volume 134, Number 2 • Scapholunate Ligament Injuries significant pain relief and 80 percent returned to their original occupation. Total wrist motion averaged 72 degrees, with grip strength 80 percent of the opposite side. Fixation techniques used include Kirschner wires, headless cannulated screws, and circular plates. Kirschner wires, however, have been associated with nonunion, with rates reported from 3 to 9 percent.39,44–46 Although it is still debated whether proximal row carpectomy or four-corner fusion is the best option for patients with grade 2 scapholunate advanced collapse changes, four-corner fusion is the procedure of choice for those patients with midcarpal arthritis (grade 3 scapholunate advanced collapse) (Reference 48, Level of Evidence: Therapeutic, IV).47,48 Four-corner fusion can be associated with nonunion and hardware problems that are not found with proximal row carpectomy. Total Wrist Arthrodesis For patients with widespread arthritic changes throughout the carpus (scapholunate advanced collapse stage 4), those who are not candidates for four-corner fusion, or those who have failed another wrist salvage procedure, wrist arthrodesis remains a final option for pain relief. Contraindications include patients who require wrist motion for transfer or where wrist motion is required to provide or augment digital motion through some tenodesis effect, such as in paraplegic patients. Patients are able to accomplish most activities of daily living with relief of pain with a unilateral wrist fusion.49,50 Partial Wrist Denervation Partial wrist denervation can be performed through neurectomy of the anterior and posterior interosseous nerves.51,52 Although this procedure does not prevent progression of osteoarthritis, decreased severity of pain has been reported in as many as 80 percent of patients undergoing this procedure.51,52 Partial wrist denervation also does not preclude subsequent total wrist arthrodesis. It may be considered in those patients who do not want either a proximal row carpectomy or fourcorner fusion.
CONCLUSIONS Scapholunate instability is the most common form of carpal instability. A thorough understanding of anatomy and biomechanics is essential for understanding the interplay between the ligaments and the carpal bones. Although early treatment is ideal, patients often present late, which necessitates salvage operations. Early
identification and management of these injuries is thought to produce better outcomes. Steven L. Moran, M.D. 200 First Street SW Rochester, Minn. 55905 [email protected]
references
1. Berger RA, Crowninshield RD, Flatt AE. The three-dimensional rotational behavior of the carpal bones. Clin Orthop Relat Res. 1982;167:303–310. 2. Landsmeer JM. Studies in the anatomy of the carpus and its bearing on some surgical problem. Acta Morphol Needer Scand. 1960;3:304–321. 3. Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg Am. 1996;21:170–178. 4. Berger RA. The anatomy and basic biomechanics of the wrist joint. J Hand Ther. 1996;9:84–93. 5. Berger RA. The ligaments of the wrist: A current overview of anatomy with considerations of their potential functions. Hand Clin. 1997;13:63–82. 6. Berger RA. The anatomy of the ligaments of the wrist and distal radioulnar joints. Clin Orthop Relat Res. 2001;383:32–40. 7. Leventhal EL, Moore DC, Akelman E, Wolfe SW, Crisco JJ. Carpal and forearm kinematics during a simulated hammering task. J Hand Surg Am. 2010;35:1097–1104. 8. Gardner MJ, Crisco JJ, Wolfe SW. Carpal kinematics. Hand Clin. 2006;22:413–420. 9. Werner FW, Green JK, Short WH, Masaoka S. Scaphoid and lunate motion during a wrist dart throw motion. J Hand Surg Am. 2004;29:418–422. 10. Palmer AK, Werner FW, Murphy D, Glisson R. Functional wrist motion: A biomechanical study. J Hand Surg Am. 1985;10:39–46. 11. Linscheid RL. Kinematic considerations in the wrist. Clin Orthop Relat Res. 1986;202:27–39. 12. Crisco JJ, Coburn JC, Moore DC, et al. In vivo radiocarpal kinematics and the dart thrower’s motion. J Bone Joint Surg Am. 2005;87:2729–2740. 13. Berger RA, Blair WF, Crowninshield RD, Flatt AE. The scapholunate ligament. J Hand Surg Am. 1982;7:87–91. 14. Berger RA, Landsmeer JM. The palmar radiocarpal liga ments: A study of adult and fetal human wrist joints. J Hand Surg Am. 1990;15:847–854. 15. Berger RA, Imeada T, Berglund L, An KN. Constraint and material properties of the subregions of the scapholunate interosseous ligament. J Hand Surg Am. 1999;24:953–962. 16. Dobyns JH, Linscheid RL. A short history of the wrist joint. Hand Clin. 1997;13:1–12. 17. Dobyns JH, Linscheid RL, Chao EYS, et al. Traumatic instability of the wrist. Instr Course Lect. 1975;24:189–199. 18. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist: Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54:1612–1632. 19. Watson H, Ottoni L, Pitts EC, Handal AG. Rotary subluxation of the scaphoid: A spectrum of instability. J Hand Surg Br. 1993;18:62–64. 20. Wolfe SW. Scapholunate instability. J Am Soc Surg Hand 2001;1:45–60. 21. Watson HK, Ballet FL. The SLAC wrist: Scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg Am. 1984;9:358–365.
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Plastic and Reconstructive Surgery • August 2014 22. Watson HK, Ashmead D IV, Makhlouf MV. Examination of the scaphoid. J Hand Surg Am. 1988;13:657–660. 23. Manuel J, Moran SL. The diagnosis and treatment of scapholunate instability. Hand Clin. 2010;26:129–144. 24. Geissler WB, Freeland AE, Savoie FH, McIntyre LW, Whipple TL. Intracarpal soft-tissue lesions associated with an intraarticular fracture of the distal end of the radius. J Bone Joint Surg Am. 1996;78:357–365. 25. Garcia-Elias M, Lluch AL, Stanley JK. Three-ligament tenodesis for the treatment of scapholunate dissociation: Indications and surgical technique. J Hand Surg Am. 2006;31:125–134. 26. Garcia-Elias M, Cooney WP, An KN, Linscheid RL, Chao EY. Wrist kinematics after limited intercarpal arthrodesis. J Hand Surg Am. 1989;14:791–799. 27. Whipple TL. Precautions for arthroscopy of the wrist. Arthroscopy 1990;6:3–4. 28. Lavernia CJ, Cohen MS, Taleisnik J. Treatment of scapholunate dissociation by ligamentous repair and capsulodesis. J Hand Surg Am. 1992;17:354–359. 29. Wyrick JD, Youse BD, Kiefhaber TR. Scapholunate ligament repair and capsulodesis for the treatment of static scapholunate dissociation. J Hand Surg Br. 1998;23:776–780. 30. Berger RA, Bishop AT, Bettinger PC. New dorsal capsulotomy for the surgical exposure of the wrist. Ann Plast Surg. 1995;35:54–59. 31. Deshmukh SC, Givissis P, Belloso D, Stanley JK, Trail IA. Blatt’s capsulodesis for chronic scapholunate dissociation. J Hand Surg Br. 1999;24:215–220. 32. Moran SL, Cooney WP, Berger RA, Strickland J. Capsulodesis for the treatment of chronic scapholunate instability. J Hand Surg Am. 2005;30:16–23. 33. Szabo RM, Slater RR Jr, Palumbo CF, Gerlach T. Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: Clinical results. J Hand Surg Am. 2002;27:978–984. 34. Moran SL, Ford KS, Wulf CA, Cooney WP. Outcomes of dorsal capsulodesis and tenodesis for treatment of scapholunate instability. J Hand Surg Am. 2006;31:1438–1446. 35. Brunelli GA, Brunelli GR. A new technique to correct carpal instability with scaphoid rotary subluxation: A preliminary report. J Hand Surg Am. 1995;20:S82–S85. 36. Watson HK, Belniak R, Garcia-Elias M. Treatment of scapholunate dissociation: Preferred treatment. STT fusion vs other methods. Orthopedics 1991;14:365–368. 37. Watson HK, Hempton RF. Limited wrist arthrodeses: I. The triscaphoid joint. J Hand Surg Am. 1980;5:320–327.
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38. Watson HK, Ryu J, Akelman E. Limited triscaphoid intercarpal arthrodesis for rotatory subluxation of the scaphoid. J Bone Joint Surg Am. 1986;68:345–349. 39. Cohen MS, Kozin SH. Degenerative arthritis of the wrist: Proximal row carpectomy versus scaphoid excision and fourcorner arthrodesis. J Hand Surg Am. 2001;26:94–104. 40. Stern PJ, Agabegi SS, Kiefhaber TR, et al. Proximal row carpectomy. J Bone Joint Surg Am. 2005;87:166–174. 41. DiDonna ML, Kiefhaber TR, Stern PJ. Proximal row carpectomy: Study with a minimum of ten years of follow-up. J Bone Joint Surg Am. 2004;86:2359–2365. 42. Richou J, Chuinard C, Moineau G, Hanouz N, Hu W, Le Nen D. Proximal row carpectomy: Long-term results. Chir Main 2010;29:10–15. 43. Jebson PJ, Hayes EP, Engber WD. Proximal row carpec tomy: A minimum 10-year follow-up study. J Hand Surg Am. 2003;28:561–569. 44. Ashmead D IV, Watson HK, Damon C, Herber S, Paly W. Scapholunate advanced collapse wrist salvage. J Hand Surg Am. 1994;19:741–750. 45. Vance MC, Hernandez JD, Didonna ML, et al. Complications and outcome of four-corner arthrodesis: Circular plate fixation versus traditional techniques. J Hand Surg Am. 2005;30:1122–1227. 46. Krakauer JD, Bishop AT, Cooney WP. Surgical treat ment of scapholunate advanced collapse. J Hand Surg Am. 1994;19:751–759. 47. Dacho AK, Baumeister S, Germann G, Sauerbier M. Comparison of proximal row carpectomy and midcarpal arthrodesis for the treatment of scaphoid nonunion advanced collapse (SNACwrist) and scapholunate advanced collapse (SLAC-wrist) in stage II. J Plast Reconstr Aesthet Surg. 2008;61:1210–1218. 48. Mulford JS, Ceulemans LJ, Nam D, Axelrod TS. Proximal row carpectomy vs four corner fusion for scapholunate (Slac) or scaphoid nonunion advanced collapse (Snac) wrists: A systematic review of outcomes. J Hand Surg Eur Vol. 2009;34:256–263. 49. Rauhaniemi J, Tiusanen H, Sipola E. Total wrist fusion: A study of 115 patients. J Hand Surg Br. 2005;30:217–219. 50. Adey L, Ring D, Jupiter JB. Health status after total wrist arthrodesis for posttraumatic arthritis. J Hand Surg Am. 2005;30:932–936. 51. Weinstein LP, Berger RA. Analgesic benefit, functional outcome, and patient satisfaction after partial wrist denervation. J Hand Surg Am. 2002;27:833–839. 52. Röstlund T, Somnier F, Axelsson R. Denervation of the wrist joint: An alternative in conditions of chronic pain. Acta Orthop Scand. 1980;51:609–616.
Learning Objectives: After studying this article, the participant should be able to: 1. Understand the pathophysiology of a scapholunate injury. 2. Understand how to diagnose scapholunate injuries 3. Formulate and carry out a surgical plan for patients with a scapholunate injury. Summary: Scapholunate ligament instability is the most common form of carpal instability. Untreated scapholunate injuries can lead to a predictable pattern of wrist arthritis. Early forms of scapholunate ligament instability can be missed, and clinical detection relies on an educated observer. This article covers the basic anatomy and biomechanics of the wrist, and reviews in detail scapholunate ligament injury. This article also reviews and discusses the current relevant topics and issues surrounding scapholunate ligament injury. (Plast. Reconstr. Surg. 134: 312e, 2014.)
T
he wrist is subject to a variety of axial and rotational loads, which can result in a variety of ligamentous injuries. This article covers the basic anatomy and biomechanics of the wrist, and reviews in detail one of the most common ligament injuries seen following wrist trauma, the scapholunate ligament injury.
ANATOMY AND BIOMECHANICS The wrist joint encompasses the distal radius and ulna, the proximal carpal row, the distal carpal row, and the bases of the five metacarpal bones. The wrist consists of four major joints: the radiocarpal, the midcarpal, the carpometacarpal, and the distal radioulnar joints. Most wrist abnormality is encountered within the radiocarpal and distal radioulnar joints. The distal carpal row is made up of the trapezium, trapezoid, capitate, and hamate. The intercarpal ligaments between the bones of the distal carpal row are stout and allow for little motion between the bones; thus, for biomechanical purposes, we can assume the distal carpal row behaves like a single bone. In contrast, the bones of the proximal carpal row, made up of the scaphoid, lunate, and triquetrum, have a moderate degree of intercarpal motion with wrist movement. Because there are no muscles that attach to the From Case Western Reserve University and the Mayo Clinic. Received for publication April 29, 2013; accepted August 14, 2013. Copyright © 2014 by the American Society of Plastic Surgeons DOI: 10.1097/PRS.0000000000000423
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proximal carpal row, the motion of these bones is in passive response to the motion of the distal carpal row and radius; thus, the proximal carpal row is termed the intercalated segment of the wrist, as it is not capable of independent motion. The ligaments that stabilize wrist motion can be divided into two general categories: those that run between the bones, termed interosseous ligaments; and those that make up the wrist capsule, running from the radius and ulna to the carpal bones, termed the extrinsic wrist ligaments. The interosseous ligaments include the scapholunate and lunotriquetral interosseous ligaments (Fig. 1). These two ligaments are the major stabilizers of the proximal carpal row and carpus.1,2 The majority of the extrinsic wrist ligaments are found palmarly and serve as secondary stabilizers of carpal motion (Fig. 2). The palmar extrinsic ligaments form an arc-shaped configuration over the carpal bones and include the radioscaphocapitate ligament, the long radiolunate ligament, and the short radiolunate ligament. The important dorsal Related Video content is available for this article. The videos can be found under the “Related Videos” section of the full-text a rticle, or, for Ovid users, using the URL citations published in the article.
Disclosure: Neither of the authors has a financial interest in any of the products or devices mentioned in this article.
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Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 1. Intrinsic ligaments of the wrist are those ligaments that both originate and insert among the carpal bones. A palmar view of the wrist demonstrates the scapholunate (SL), lunotriquetral (LT), trapezium-trapezoid (TT), the capitotrapeziod (CT), capitohamate (CH) intrinsic, the scaphotrapeziumtrapezoid (STT), the scaphocapitate (SC), the triquetrocapitate (TC), and the triquetrohamate (TH) ligaments. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
extrinsic ligaments include the dorsal radiocarpal ligament, which is an important secondary stabilizer of scaphoid motion.2–6 For simplicity, wrist motion can be broken down into three major arcs that include radial and ulnar deviation, flexion and extension, and the “dart-thrower’s” arc. The dart-thrower’s arc involves an oblique plane moving from radial deviation and wrist extension to ulnar deviation and wrist flexion. This arc is considered to be involved in many daily activities.7–10 The distal pole of the scaphoid extends into the distal carpal row, allowing the scaphoid to function as a link between the proximal and distal carpal rows.11 During wrist radial deviation and wrist flexion, the scaphoid is pushed into flexion by the distal carpal row; as this occurs, the scaphoid pulls the lunate into flexion through the pull of the scapholunate interosseous ligament. The lunate, in turn, pulls the triquetrum into flexion through the stout attachment of the lunotriquetral interosseous ligament. During ulnar deviation and wrist extension, the distal carpal row, through the helical articulation between the hamate and
triquetrum, pushes the triquetrum into extension. The triquetrum then pulls the rest of the proximal carpal row into extension through intact lunotriquetral and scapholunate interosseous ligaments. During the dart-thrower’s arc, motion at the scaphoid and lunate is limited, and the majority of carpal motion occurs through the midcarpal joint. Because this arc of motion does not result in significant motion between the scaphoid and the lunate, it may have important implications in wrist rehabilitation following scapholunate interosseous ligament repair.7,8,12 When there is an injury to either the scapholunate interosseous ligament or lunotriquetral interosseous ligament, the bones of the proximal carpal row become unlinked and will move abnormally; this is referred to as carpal instability. Over time, this abnormal motion stretches the surrounding extrinsic ligaments, leading to further instability and radiographic abnormalities. Abnormal carpal motion leads to cartilage damage and eventual wrist arthritis.1,2,13–15 The most common form of carpal instability is scapholunate dissociation.16–18 The timeline for developing arthritis following scapholunate interosseous ligament injury is still unknown.
SCAPHOLUNATE LIGAMENT INJURY Injury to the scapholunate interosseous ligament is usually the result of a fall onto an extended wrist and may present as an isolated injury or in association with a distal radius fracture, scaphoid fracture, or perilunate dislocation. There are several chronic conditions that may also predispose to the development of an attritional tear of the scapholunate interosseous ligament, and these include Kienböck disease, rheumatoid arthritis, and pseudogout. Injury to the scapholunate interosseous ligament usually begins in the palmar component of the ligament, which is less stout than the dorsal component. The injury then progresses dorsally until a complete tear is present. Partial tears may produce only pain with activity and result in little abnormality in scaphoid motion; however, complete ruptures of the scapholunate interosseous ligament result in dissociation of the scaphoid from the lunate, preventing the scaphoid from exerting any force on the lunate. Consequently, there is an unopposed extension force exerted on the lunate by the triquetrum through the intact lunotriquetral interosseous ligament. Over time, if the scapholunate interosseous ligament is not repaired, the lunate will be pulled into a permanent position of extension. When this abnormality is noted on a
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Fig. 2. Extrinsic ligaments of the wrist include those ligaments that originate outside the carpal bones and insert onto the carpal bones. From a volar view (left), the proximal ligaments from radial to ulnar include the radioscaphocapitate (RSC), long radiolunate (LRL), short radiolunate (SRL), ulnolunate (UL), ulnocapitate (UC), and ulnotriquetral (UT). R, radius; U, ulna; RA, radial artery; AIA, anterior interosseous artery; PRU, palmar radioulnar ligament; S, scaphoid; P, pisiform; T, triquetrum; Tm, trapezium; Td, trapezoid; C, capitate; H, hamate. (Right) Illustration of the extrinsic dorsal wrist ligaments. There is only one true dorsal extrinsic ligament, the radiotriquetral ligament or dorsal radiocarpal (DRC) ligament as it is more commonly called. The scaphotriquetral ligament, also called the dorsal intercarpal (DIC) ligament, is by definition an intrinsic ligament, but is often thought of as an extrinsic ligament, as it crosses three bones. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
lateral radiograph of the wrist, it is termed a dorsal intercalated segment instability. Unopposed scaphoid flexion and lunate extension result in abnormal radiographic findings on lateral radiographs that include an increase in the scapholunate angle and radioscaphoid angle (Fig. 3). Ongoing scaphoid flexion results in dorsal subluxation of the scaphoid from the radial fossa. This leads to a progressive pattern of wrist arthritis termed scapholunate advanced collapse or scapholunate advanced collapse wrist (see Fig. 5).17,18 Ongoing lunate extension creates abnormal forces at the midcarpal joint, resulting in capitolunate arthrosis over time; in most cases, the radiolunate joint is spared significant arthritic wear despite scapholunate interosseous ligament injury. Scapholunate interosseous ligament injury can present within a spectrum of severity that is related to the status of the remaining ligament and surrounding extrinsic ligaments.19 This spectrum has been broken down into four categories of instability:
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1. Predynamic instability. This is the mildest form of scapholunate interosseous ligament injury and results from a stretched or partially torn scapholunate interosseous ligament. Patients complain of dorsal wrist pain following heavy exertion or lifting but have normal radiographs. Abnormalities within the scapholunate interosseous ligament at this stage can usually be seen only with arthroscopic examination. 2. Dynamic instability. In this stage of injury, the extrinsic wrist ligaments and portions of the scapholunate interosseous ligament may still be intact; however, abnormalities can be seen on radiographs when the wrist is loaded (e.g., in a clenched-fist radiograph) (Fig. 4) or placed into the extremes of motion under fluoroscopy. The intact secondary stabilizers of scaphoid motion are able to maintain normal carpal alignment when the wrist is not being subjected to loading conditions thus plain radiographs can appear normal.
Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 3. Scapholunate interosseous ligament injury can produce abnormalities in the position of the scaphoid and lunate bones that can be visible on anteroposterior and lateral radiographs. (Left) Anteroposterior radiograph in a patient with a static scapholunate injury, showing an increase in the distance between the scaphoid and lunate, which is referred to as scapholunate diastasis. In addition, the lateral radiograph (right) shows an increased scapholunate angle (>60 degrees). The lunate is tilted dorsally greater than 15 degrees, representing a dorsal intercalated segment instability deformity.
Fig. 4. Clenched-fist radiograph in a 52-year-old man with dynamic scapholunate instability. Notice that the right wrist displays a widened scapholunate interval compared with the left side.
3. Static scapholunate dissociation. When a complete scapholunate interosseous ligament tear occurs with attenuation or attrition of the supporting wrist ligaments, permanent misalignment will occur within the carpus and radiographic changes will be visible on resting, or static, radiographs. If such deformity is present on lateral and posterior anterior radiographs, we can diagnose the patient with static scapholunate dissociation.20 The term static here refers to the fact that radiographic abnormalities are seen in the wrist at rest and do not require
loading or some other dynamic maneuver for identification (Fig. 3). 4. Scapholunate advanced collapse arthritis. Longstanding carpal malalignment, following scapholunate interosseous ligament disruption, will result in cartilage damage and arthritis. This arthritis follows a typical progression and has been divided into three grades. The arthritic changes are visualized initially at the radial styloid, and this has been classified as scapholunate advanced collapse stage 1; arthritic changes are then seen at the radioscaphoid fossa, which is classified as
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Fig. 5. (Left) Anteroposterior radiograph in a patient with stage 2 scapholunate advanced collapse arthritis. Note the arthritic changes present at the radioscaphoid articulation. (Right) Anteroposterior radiograph in a patient with stage 3 scapholunate advanced collapse arthritis. Note the arthritic changes at the radioscaphoid fossa and at the capitolunate articulation.
scapholunate advanced collapse stage 2 (Fig. 5). In scapholunate advanced collapse stage 3, arthritic changes are seen in the midcarpal joint over the head of the capitate, as progressive scapholunate diastasis allows proximal migration of the capitate head (Fig. 5) (Reference 21, Level of Evidence: Therapeutic, IV).20,21 Although not part of the original staging system, and still considered controversial by many authors, scapholunate advanced collapse stage 4 would represent a wrist with arthritis extending throughout the midcarpal and radiocarpal joints. Diagnosis of Scapholunate Ligament Injury In acute scapholunate interosseous ligament injuries, physical findings may include swelling in the anatomical snuffbox and dorsal radiocarpal joint. Weakness and pain are associated with wrist loading activities. Patients may describe their wrist as “unstable,” often stating that the wrist feels “like it is going to give way” under loads. Chronic injuries may present with wrist pain and symptoms of carpal tunnel syndrome caused by underlying wrist synovitis. During physical examination, the scapholunate joint can be palpated directly by bringing the wrist into flexion and palpating 1 cm distal to the Lister tubercle. Tenderness in this area may indicate a tear. The scaphoid shift test, or Watson test, is a provocative maneuver that can help to diagnose scapholunate interosseous ligament injuries. The wrist is moved from ulnar to radial deviation
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with the examiner’s thumb pressing against the scaphoid tubercle. Patients with partial tears will have an increase in pain dorsally over the scapholunate articulation. An audible clunk may signify a complete tear, as the scaphoid is actively subluxed off the dorsum of the radius with radial deviation and spontaneously reduces into the radial fossa when the wrist is brought back into ulnar deviation. The contralateral wrist should be examined for comparison, as the scaphoid shift test may be falsely positive in up to one-third of individuals because of ligamentous laxity without injury. Progressive loss of grip strength with a repetitive gripping maneuver may also signify a scapholunate interosseous ligament injury.22 Plain radiographs are always obtained to evaluate for fracture or other abnormality. Evidence for a scapholunate interosseous ligament injury can be made by evaluating the posteroanterior and lateral wrist radiographs. The following are suggestive of a static scapholunate injury (Fig. 4).23 1. The Terry Thomas sign. Diastasis between the scaphoid and lunate with a gap greater than 3 mm. 2. The scaphoid ring sign. Excess projection of the distal pole from abnormal scaphoid flexion giving the appearance of a ring. 3. Disruption of the Gilula lines of the carpus. On lateral radiographs, a dorsal intercalated segment instability deformity may be visible with an increased scapholunate angle greater than 60
Volume 134, Number 2 • Scapholunate Ligament Injuries degrees (a normal scapholunate angle is approximately 45 degrees) or an increased radiolunate angle greater than 15 degrees (Fig. 4).23 If plain radiographs do not show abnormalities, magnetic resonance imaging can be used to diagnose partial or dynamic injuries. Computed tomography is not a sensitive modality for assessing ligamentous abnormality. If there are no abnormalities visible on imaging studies and the surgeon is still suspicious for a scapholunate interosseous ligament injury, one should consider wrist arthroscopy. Wrist arthroscopy is considered the criterion standard for diagnosis of wrist ligament injuries, as it allows direct inspection of the interosseous ligaments and surrounding extrinsic ligaments. Both radiocarpal and midcarpal arthroscopy should be performed to diagnose interosseous ligamentous instability; however, midcarpal arthroscopy (Fig. 6) is the key to assessing the stability of the scapholunate joint. (See Video, Supplemental Digital Content 1, which displays a video recording of radiocarpal and then midcarpal arthroscopy illustrating findings of scapholunate ligament injury, available in the “Related Videos” section of the full-text article on PRSJournal.com or, for Ovid users, at http://links.lww.com/PRS/B44.) The degree of injury can be graded arthroscopically based on the Geissler classification (Table 1).24 Treatment of Scapholunate Ligament Injury Once the diagnosis of scapholunate interosseous ligament injury has been made, there are
Video. Supplemental Digital Content 1, which displays a video recording of radiocarpal and then midcarpal arthroscopy illustrating findings of scapholunate ligament injury, is available in the “Related Videos” section of the full-text article on PRSJournal. com or, for Ovid users, at http://links.lww.com/PRS/B44.
several different treatment options based on the severity of the disease. Mildly symptomatic patients can be treated conservatively with wrist splinting and activity modification. Surgical treatment of scapholunate dissociation is dependent on the severity of the instability (i.e., predynamic, dynamic, or static), the chronicity of the injury, and the presence of any degenerative changes to the carpus. Treatment options have been summarized by Garcia-Elias et al. in recent reviews.25,26 Table 1. Geissler Arthroscopic Classification of Carpal Interosseous Ligament Tears* Grade I II
III
IV Fig. 6. Midcarpal arthroscopy as viewed through the radial midcarpal portal shows the scaphoid (S) and lunate (L) bones. A probe is within the palmar portion of the scapholunate interosseous ligament. Hemorrhage can be seen within the synovium surrounding the ligament, indicative of scapholunate interosseous ligament injury.
Description Attenuation and hemorrhage of interosseous ligament seen from radiocarpal joint, with no step-off present as seen from midcarpal joint Attenuation and hemorrhage of interosseous ligament seen from radiocarpal joint, with step-off as seen through midcarpal joint; the probe can be placed between scaphoid and lunate Incongruence or step-off is seen between the scaphoid and the lunate from both the radiocarpal and midcarpal portals; the probe can be placed and freely rotated between the scaphoid and lunate Incongruence or step-off is seen between the scaphoid and the lunate from both the radiocarpal and midcarpal portals; gross instability is noted, and the 2.7-mm arthroscope may be passed through the gap between the scaphoid and lunate
*From Geissler WB, Freeland AE, Savoie FH, McIntyre LW, Whipple TL. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg Am. 1996;78:357–365.
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Plastic and Reconstructive Surgery • August 2014 Acute Injuries In acute injuries, arthroscopy can be used to determine the extent of scapholunate interosseous ligament injury. Some studies have suggested that partial tears may be treated by percutaneous pinning of the scaphoid and lunate, thus allowing for the possibility of primary healing or fibrosis. Open repair of acute, complete scapholunate interosseous ligament tears has been shown to maintain grip strength and wrist motion and presumably halts the progression to degenerative changes and the development of a scapholunate advanced collapse wrist.23,27 Chronic Injuries Treatment options for chronic scapholunate interosseous ligament injuries are dependent on the presence of degenerative arthritis. If scapholunate advanced collapse arthritis is present, attempts at reconstruction of the scapholunate interosseous ligament are discouraged and some type of wrist salvage procedure is performed. The most common wrist salvage procedures performed for scapholunate advanced collapse arthritis are scaphoidectomy and fourcorner fusion or proximal row carpectomy. In the absence of arthritis, treatment is directed at reconstructing the scapholunate interosseous ligament; if the scapholunate interosseous ligament is not reconstructible because of the severity of the tear or attritional changes, some other means must be used to stabilize the scaphoid and restore the scapholunate relationship (Fig. 7). Several methods have been described, and these include capsulodesis procedures, tenodesis procedures, and limited intercarpal fusion. Surgical Management of Scapholunate Interosseous Ligament Injury Scapholunate Ligament Repair Direct ligament repair can be used to repair acute scapholunate interosseous ligament injuries, and can be considered in cases of chronic ligament injury if (1) there is satisfactory ligament present for repair, (2) the scaphoid and lunate are still easily reducible, and (3) there is no evidence of arthritis within the carpus. Ligament repair may be performed with the use of suture anchors, interosseous sutures, or interosseous wires. Recent reports have also described augmentation of the ligament with different types of biological tendon replacements. After repair, the joint is pinned and immobilized in a cast for 6 to 8 weeks.23,28 Open repair of acute scapholunate interosseous ligament tears has been shown to maintain adequate
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Fig. 7. Example of a chronic scapholunate interosseous ligament tear seen following exposure of the wrist joint through a dorsal approach. Kirschner wires have been placed into the scaphoid (s) and lunate (L) to aid with reduction of the bones. Primary repair of the ligament is not possible in this case, as the ligament has degenerated and would be incapable of holding a stitch.
grip strength and wrist motion with minimal progression to degenerative changes.28,29 The open technique for scapholunate interosseous ligament repair is generally performed through a dorsal midline incision. The extensor retinaculum is divided over the third dorsal compartment and the extensor pollicis longus tendon is retracted radially. Retinacular flaps are elevated from the third dorsal compartment to the second compartment radially and from the third dorsal compartment to the fifth compartment ulnarly. A ligament-sparing capsulotomy is performed (Fig. 8), as described by Berger et al., to gain access to the carpus.30 This capsulotomy is in line with the fibers of the dorsal intercarpal ligament and dorsal radiocarpal ligament; this facilitates closure and minimizes damage to the dorsal extrinsic ligaments. Care is taken to elevate a full-thickness flap that does not violate the dorsal components of the scapholunate interosseous ligament and lunotriquetral interosseous ligament. If a capsulodesis is being considered for management of scapholunate interosseous ligament injury, care should be taken to leave the dorsal capsule attached to the scaphoid waist. After surgical exposure, the carpus is evaluated. The scapholunate interosseous ligament is usually
Volume 134, Number 2 • Scapholunate Ligament Injuries
Fig. 8. Scapholunate repair is usually accomplished through a dorsal approach to the wrist. A ligament-sparing capsulodesis creates a radially based flap that follows the fibers of the dorsal radioscaphotriquetral ligament and dorsal intercarpal ligament (left and center). This flap allows excellent exposure of the scapholunate joint as shown in Figure 7. The bones are then held in position with percutaneous Kirschner wires. After reduction, the primary repair or capsulodesis can be performed with the use of suture anchors. (Right) Postoperative radiograph of a woman who has undergone a scapholunate repair in conjunction with a Mayo-type dorsal capsulodesis. (Left and center, reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
torn off the scaphoid. The scapholunate relationship is reestablished with the aid of Kirschner wires, which are placed dorsally into the scaphoid and lunate to act as joysticks. The scapholunate interface is reduced and the bones are held with two or three Kirschner wires. The midcarpal joint may also be pinned for added stabilization. The scapholunate interosseous ligament is then repaired with bone anchors (Fig. 8). Kirschner wires are left for 8 to 10 weeks and patients are protected from full loading for an additional 4 to 6 weeks.28 Capsulodesis and Tenodesis When primary repair is not possible because of attrition of the scapholunate interosseous ligament, unopposed flexion of the scaphoid can be controlled with the use of capsulodesis or tenodesis procedures. Capsulodesis uses a portion of the dorsal wrist capsule to tether the scaphoid, and prevents it from flexing. A variety of capsulodesis procedures have been described (Fig. 9), but none has been shown to produce superior results (Reference 32, Level of Evidence: Therapeutic, IV).31,32 This technique is useful in conjunction with ligament repair for chronic instability or may also be used alone for cases of dynamic instability. Unfortunately, long-term outcome studies examining capsulodesis procedures have yielded mixed results in terms of wrist function and maintenance of carpal alignment.32,33
Tenodesis procedures use tendons to either tether carpal bone motion or to replace and reconstruct the scapholunate interosseous ligament. A variety of tenodesis procedures have been described. The most common form of tenodesis is the Brunelli tenodesis that uses half of the flexor carpi radialis tendon passed through a bone tunnel in the scaphoid and secured dorsally to the distal radius or lunate. The problem with all tenodesis procedures is that the elastic moduli of tendon and ligament are not equivalent. Restriction of scaphoid motion using a tendon usually requires a significant degree of tension on the tendon, which can restrict overall wrist motion (Reference 34, Level of Evidence: Therapeutic, III).25,34,35 Intercarpal Fusion In cases of chronic instability when the scapholunate malalignment is not reducible and there is not yet evidence of cartilage degeneration, limited intercarpal fusions can be performed; scaphotrapezial-trapezoidal and scaphocapitate arthrodesis have both been advocated to restrict scaphoid motion. Intercarpal fusion stabilizes the scaphoid and restores its alignment with the distal radius. Unfortunately, scaphotrapezial-trapezoidal and scaphocapitate fusions alter carpal kinematics, leading to an increased load across the radioscaphoid fossa. Over time, these fusions
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Fig. 9. Capsulodesis procedures use a portion of the dorsal wrist capsule to control scaphoid flexion. Here, one sees an example of a Mayo-type capsulodesis where a portion of the dorsal intercarpal ligament is used to tether the scaphoid in an extended position. (Reproduced by permission of the Mayo Foundation for Medical Education and Research. All rights reserved.)
Fig. 10. Anteroposterior radiograph of a patient who has undergone a proximal row carpectomy.
have been shown to result in the development of degenerative arthritis within the wrist.36–38 Surgical Management of Scapholunate Advanced Collapse Arthritis Once patients show evidence of radiocarpal arthritis, it is recommended that some type of wrist salvage procedure should be performed, as attempts to reconstruct the scapholunate interosseous ligament could still leave the patient with ongoing pain. The two most common procedures used are proximal row carpectomy (Fig. 10) and scaphoid excision and four-corner bone fusion (Fig. 11). These procedures can provide pain relief and preserve some wrist motion (Level of Evidence: Therapeutic, II).39 Proximal Row Carpectomy Removal of the scaphoid, lunate, and triquetrum with meticulous capsular repair allows the capitate to articulate with the lunate fossa of the distal radius, preserving wrist motion and removing the diseased proximal carpal bones (Fig. 10). Good long-term results at 10-year follow-up have been achieved, with total wrist motion ranging from 63 to 76 degrees and grip strength up to 91 percent of the contralateral side.40–43 Advantages include a shortened period of postoperative immobilization and no requirement for bone fusion, which is an issue of concern in smokers. The main contraindication for this procedure is
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Fig. 11. Anteroposterior radiograph of a patient who has undergone a four-corner fusion and scaphoidectomy using plate-andscrew fixation.
arthritic changes at the lunocapitate joint, which prevent creation of a stable articulation between the capitate and radiolunate fossa. Long-term radiographic changes include arthritis at the radiocapitate interface in most patients 10 years after surgery. It is not clear what impact these changes will have on longer follow-up. Four-Corner Arthrodesis This procedure involves fusion of the lunate, triquetrum, capitate, and hamate, with removal of the scaphoid (Fig. 11). The radiolunate articulation must be intact without carpal subluxation. In the largest single series of 100 patients by Ashmead et al.,44 91 percent of patients had
Volume 134, Number 2 • Scapholunate Ligament Injuries significant pain relief and 80 percent returned to their original occupation. Total wrist motion averaged 72 degrees, with grip strength 80 percent of the opposite side. Fixation techniques used include Kirschner wires, headless cannulated screws, and circular plates. Kirschner wires, however, have been associated with nonunion, with rates reported from 3 to 9 percent.39,44–46 Although it is still debated whether proximal row carpectomy or four-corner fusion is the best option for patients with grade 2 scapholunate advanced collapse changes, four-corner fusion is the procedure of choice for those patients with midcarpal arthritis (grade 3 scapholunate advanced collapse) (Reference 48, Level of Evidence: Therapeutic, IV).47,48 Four-corner fusion can be associated with nonunion and hardware problems that are not found with proximal row carpectomy. Total Wrist Arthrodesis For patients with widespread arthritic changes throughout the carpus (scapholunate advanced collapse stage 4), those who are not candidates for four-corner fusion, or those who have failed another wrist salvage procedure, wrist arthrodesis remains a final option for pain relief. Contraindications include patients who require wrist motion for transfer or where wrist motion is required to provide or augment digital motion through some tenodesis effect, such as in paraplegic patients. Patients are able to accomplish most activities of daily living with relief of pain with a unilateral wrist fusion.49,50 Partial Wrist Denervation Partial wrist denervation can be performed through neurectomy of the anterior and posterior interosseous nerves.51,52 Although this procedure does not prevent progression of osteoarthritis, decreased severity of pain has been reported in as many as 80 percent of patients undergoing this procedure.51,52 Partial wrist denervation also does not preclude subsequent total wrist arthrodesis. It may be considered in those patients who do not want either a proximal row carpectomy or fourcorner fusion.
CONCLUSIONS Scapholunate instability is the most common form of carpal instability. A thorough understanding of anatomy and biomechanics is essential for understanding the interplay between the ligaments and the carpal bones. Although early treatment is ideal, patients often present late, which necessitates salvage operations. Early
identification and management of these injuries is thought to produce better outcomes. Steven L. Moran, M.D. 200 First Street SW Rochester, Minn. 55905 [email protected]
references
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