European Journal of Trauma and Emergency Surgery
Focus on Elbow Fractures
Radial Head Fractures: Indications and Technique for Primary Arthroplasty Jan E. Madsen1,2, Gunnar Flugsrud2
Abstract The treatment of complex radial head fractures remains a challenge for the orthopedic surgeon. Novel implants and improved surgical techniques have made reconstruction of the radial head with open reduction and internal fixation possible in most cases. However, extremely comminuted radial head fractures with associated instabilities still require replacement of the radial head with a prosthesis to allow rehabilitation with early motion of the elbow, and thereby optimizing the functional results of these potentially devastating injuries. In this article we discuss the surgical considerations related to radial head replacement, encompassing the indications for radial head arthroplasty, implant selection, surgical technique, rehabilitation protocols, and complications related to radial head prosthesis. Key Words Radial head fracture Æ Arthroplasty Æ Radial head prosthesis Eur J Trauma Emerg Surg 2008;34:105–12 DOI 10.1007/s00068-008-8023-y
Introduction Management of radial head fractures requires thorough knowledge of the radial head function in stabilizing the elbow and forearm. Elbow kinematics is complex, with the radial head moving in extension and flexion as well as in rotation of the forearm. Regardless of fracture type, the goals of treatment of the radial head fractures are restoration of elbow stability, preservation of elbow range of motion, and maintenance of the length of the radius. In simple fracture patterns this is accomplished by a short
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immobilization period, followed by early motion exercises. In the complex fracture patterns the clinical decision making becomes more difficult, and needs to be individualized according to the nature of the radial head fracture, associated injuries and each patient’s demands. Historically, radial head resection was the surgical solution in difficult cases of radial head fractures, and may indeed provide reliable pain relief and good range of motion in low– demand patients when associated bone – or ligamentous injuries are absent [1, 2]. However, this is rarely the case, and later reports have outlined inferior results of radial head excision in complex injuries [3–5]. Our ability to fix or replace the radial head after fractures has improved greatly during the last decades, due to improvements of instrumentation and techniques, both regarding internal fixation and radial head arthroplasty. Also, the importance of the radial head as an important elbow and forearm stabilizer has been increasingly emphasized, and understanding of the complex elbow injuries has gradually improved. Thus, in modern decision making, the surgeon needs to decide whether open reduction and internal fixation of the fracture is technically feasible, or whether reconstruction with a radial head arthroplasty is needed.
Understanding the Complex Elbow Injury According to the complex nature of many elbow injuries, and the injury pattern’s impact on treatment, a thorough analysis of each individual injury is of utmost importance for decision making. The main pitfall is to underestimate the associated injuries to the other stabilizing structures of the joint; in the patient with a radial head fracture associated injuries should always be considered.
Faculty of Medicine, University of Oslo, Oslo, Norway, Orthopedic Center, Ullevål University Hospital, Oslo, Norway.
Received: February 11, 2008; accepted: February 18, 2008; Published Online: April 2, 2008
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The radial head is a main contributor to elbow stability and force transmission from the hand to the upper arm. In a cadaver study, Halls and Travill demonstrated that as much as 60% of a load applied to the hand was transmitted through the radiocapitellar joint during resisted flexion, even when the interosseous membrane of the forearm was transected [6]. The force transmission is greatest in extension and pronation, and decreases toward increased elbow flexion. This can result in forces up to 90% of the body weight across the radiocapitellar joint [7]. Furthermore, several studies have confirmed that a radial head resection results in decreased resistance to valgus load of the elbow [8–10], and the radial head is even more essential for elbow stability when there is concurrent damage to the collateral ligaments; In Morrey’s study, radial head resection did not alter the kinematics of an otherwise intact elbow. Release of the medial collateral ligaments caused only a moderate (6–8°) increase in abduction rotation, whereas releasing both lateral and medial ligaments caused gross abduction laxity and elbow subluxation [11]. These findings imply that the implants used for internal fixation, as well as prosthesis used for replacement, must be able to withstand significant loads. And, furthermore, they imply that radial head resection may be an option in comminuted radial head fractures in an otherwise unharmed elbow joint. However, there is a high likelihood of associated injuries to the medial collateral ligaments in patients who have had strong enough forces applied to the elbow to produce extensive comminution of the radial head. And indeed, numerous reports have outlined the potential disadvantages of radial head excision, including decreased grip strength, weak forearm rotation, radial shortening with subsequent wrist pain, and evidence of late arthritic changes [3–5], probably reflecting the high incidence of undiagnosed associated injuries. Due to this, and the fact that modern implants and surgical technique have enabled us to fix or replace most injuries to the radial head, the option of primary radial head resection is very nearly abandoned in our daily practice. To ease decision making, several attempts have been made to classify the injured radial head. Mason’s original classification [12] was put forward in a time when resection or conservative treatment were the only options, and did not account for radial neck fractures, degree of displacement or associated injuries. Today, this classification is of little value in guiding treatment. For this reason, we tend to use Hotchkiss’ modification of the Mason classification
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[13], where type I fractures represent non- or minimally displaced fractures amenable to conservative treatment, type II are displaced fractures technically possible to repair by ORIF, and type III are the severely comminuted fractures judged nonreconstructable by internal fixation. An objection to this classification is that it may have elements of a posthoc treatment – classification, describing a performed treatment without describing the injury’s characteristics or reasons for the choice of treatment. Obviously, with improved implants and surgical technique some of the previous type III fractures are at present fixable, and should be considered type II. The type III fractures then come to include very severely comminuted radial head fractures with resection or replacement as the only treatment options. As associated injuries are common in these cases, and resection hampered with disadvantages, the type III fractures should be treated with radial head replacement. During the last decade standardized surgical protocols for treating elbow dislocations with concomitant fractures have been developed [14–16]. Common to these concepts are early intervention with stable fixation of radial head and coronoid fractures, and repair of torn ligaments to provide sufficient stability to allow early motion. Ring and Jupiter [16], outlined the anatomical restraints of the elbow as components of a ring, with anterior, posterior, medial, and lateral columns or components contributing to stability (Figure 1). This model is very useful in diagnosing and stabilizing the unstable elbow; if one part of the ring (i.e., the radial head) is injured, disruptions of the other columns should always be sought for. During repair, each column is systematically addressed to restore stability. If the radial head is fractured, this involves stable internal fixation if technically possible, or replacement with radial head prosthesis.
Indications for Primary Radial Head Replacement As the radial head is of utmost importance for elbow stability, it should be preserved whenever rigid internal fixation is obtainable [13, 17, 18]. The ability to perform stable fixation of these fractures have improved with time, as both novel implants and improved surgical technique have pushed the limits for what is considered reconstructable, slowly moving the border between type II and type III fractures. Angular stable implants may represent a significant step forward in performing internal fixation of comminuted radial head fractures; superior stability has been proved in a
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Figure 1. The stabilizing structures of the elbow illustrated as a ring [16]. This model invites a systematic approach to diagnosis and treatment of the elbow injuries; if one column is injured (i.e., the radial head), other disruptions should be actively sought for and dealt with to restore joint stability. The injury complexity increases with the number of columns involved. (From: Ring D, Jupiter JB. Fracturedislocation of the elbow. The Journal of bone and joint surgery. 1998 Apr;80(4):566–80. Reprinted with permission from The Journal of Bone and Joint Surgery, Inc).
cadaver study [19], but is not yet verified in clinical trials. Radial head resection should rarely be considered, and only in elderly, low demand patients without associated injuries. Associated ligamentous injuries may be difficult to diagnose, and their recognition and proper treatment are key factors in treating these injuries. The still valid, present indications for primary radial head replacement have previously been summarized [20] to include irreparable radial head fractures in combination with: Any elbow dislocation Medial collateral ligament disruption Lateral ulnar collateral ligament dysfunction Monteggia variants with olecranon fractures
Coronoid process fracture Forearm interosseous membrane disruption (Essex–Lopresti) It should be noted that the irreparable radial head in some cases constitutes a rim fracture, sized >30%. In these cases it is probably better to insert a radial head prosthesis than to leave a significant rim defect, which is likely to lead to recurrent instability. The need for radial head replacement after delayed resection has been questioned [21, 22], and is rarely used in our practice. In cases of early failure of internal fixation in type II fractures, however, radial head prostheses are useful in regaining elbow stability,
Figures 2a and 2b. Overstuffing of the radiocapitellar joint is a common pitfall. This 57-yearold woman sustained a dislocated elbow after falling off her bicycle and an irreparable radial head fracture led to prosthetic replacement. a) The prosthesis is inserted only 1–2 mm too proud compared to the lateral edge of the coronoid process, b) leading to a subtle incongruence of the ulno – humeral joint.
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and good results might be expected in these often difficult cases [23] (Figure 2).
Prosthetic Replacement of the Radial Head Speed reported the first prosthesis to replace the radial head in 1941 [24]. These first arthroplasties were intended to prevent proximal migration of the radius, cubitus valgus and heterotopic ossification. During the next decades, radial head prostheses of different materials were introduced, performing better than the previously used radial head resection. Acrylic implants [25] proved too brittle to support the loads over the radiocapitellar joint, with 2 fractures in 14 patients in Edwards’ series [26]. Swanson introduced the silicone arthroplasty [27], and the silastic implants stayed in vogue for some years, until complications became apparent with fracture of the implants and siliconebased synovitis [28, 29]. Together with experimental studies [8, 9], these findings suggested that silicone prosthesis was not rigid enough to support the lateral column, and they should no longer be routinely used. Presently, a number of metallic radial head prosthesis is available, in various designs [30]. Recognizing that the complex kinematics of the elbow joint is difficult to recreate with a radial head arthroplasty, two different concepts have evolved [31]: 1. A polished stem with a monobloc or modular head, intended to be placed as an intentionally loose metal spacer, or 2. A rigidly fixed stem with a modular or bipolar head. Both concepts have proved better than radial head resection in the unstable elbow, but there is a lack of long-term results in the literature. In Harrington et al.’s work, 16 of 20 patients had a good or excellent result 6– 29 years after treatment for comminuted radial head fractures with associated instability with an intentionally loose polished stem implant [32]. These implants, however, induce radiolucent zones around the stem, as was shown in 17 of 25 patients at an average of 39 months in Moro’s study [33] and later confirmed [31]. The clinical significance of this finding is uncertain. Many authors have favored fixed stem arthroplasties, with press-fit or bone cement fixation. Bone cement is advocated in combined head and neck fractures, and we have found it useful in most fracture cases. Bipolar heads were introduced by Judet in 1996 [34], and have proven good clinical results in the
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medium-term [35, 36]. Even though these bipolar implants may be theoretically advantageous, some concerns exist: In Popovic et al.’s paper, radiographic changes indicating progressive osteolysis around the stem were present in 37 out of 50 patients, mean 8.4 years after the index operation. This finding may be due to polyethylene wear within the stem/head articulation; the polyethylene insert is thin (approximately 3 mm), and the loads transmitted over the articulation are significant [36]. The long-term significance of these findings needs to be addressed in further studies. Whether unipolar, fixed stem prosthesis shows the same evidence of radiographic lucencies in the longterm, is largely unknown. At present we prefer to use a modular, fixed stem implant with a variety of stem sizes, head diameters and head heights (rHeadTM, Small Bone Innovations, Morrisville, Pennsylvania). These implants require minimal neck resections, and allow a fairly close individualization of the prosthesis according to the native size and shape of the radial head. Surgical Technique In the severely injured elbow each injured column is addressed sequentially according to a standardized protocol, as previously described [14–16]. We prefer to position the patient supine, with a tourniquet applied and the injured arm resting on a radiolucent hand table. Even though this is not confirmed in clinical studies, one might expect overstuffing of the radiocapitellar joint to correlate with inferior results [37, 38]. It is therefore of major importance to choose a correct diameter implant, and to perfectly recreate the length of the radius and the position of the radial head relative to the ulna. As there are considerable individual variations in the anatomical relationship between the proximal radius and ulna [39], we use the C-arm in the operating theatre, before the patient is scrubbed, to obtain an exact AP projection of the uninjured elbow. This image later serves as a template for the exact positioning of the radial head prosthesis. AP views of both wrists are also obtained, to rule out, and enable correction for a relative shortening of the radius due to an Essex–Lopresti injury. Skin incisions are chosen according to the pattern of associated injuries. For the radial column a lateral skin incision is preferred. The Kocher interval between the anconeus and extensor carpi ulnaris muscles is used in most cases. When a radial approach to the coronoid process is planned, it may be more convenient to go between the extensor digitorum and extensor carpi radialis muscles. The muscles are retracted to expose
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the lateral ligament complex, which is incised anterior to the lateral ulnar collateral ligament, either in a longitudinal or Z-shaped fashion [40]. In most cases with ulnohumeral dislocations, the radial collateral ligaments are torn off the humeral epicondyle, making the radial approach easy. Coronoid fractures may be approached from the lateral side in anterolateral coronoid fracture patterns, after the humeral head pieces have been removed. If the coronoid fracture is comminuted and includes the ulnar side with the ulnar collateral ligament insertion, a separate, medial approach to the medial column is preferred. The long, posterior skin incision advocated by many authors [16, 33, 41] is well suited with a laterally positioned patient, and especially with severe, associated fractures to the proximal ulna. In the supine position with a structurally intact ulna, we find it easier to use separate medial and lateral incisions. The surgical technique for prosthesis insertion varies according to different implants. After identification and removal of all fracture fragments, and repair of the coronoid process if required, the diameter of the prosthesis is chosen according to the removed head pieces, as close to the native radial head as possible. The radial neck resection is performed according to the implant’s requirements, with or without a resection guide. In general, as little bone as possible should be removed from the radial neck. Mostly, this involves only careful adaptation of the fracture surfaces using bone pliers. Since the exact positioning of the prosthesis is of utmost importance, the direction of the neck osteotomy must be thoroughly adjusted utilizing trial implants; this ensures centering of the implant toward the capitellum, and helps to avoid ‘‘edge binding’’ [30] and impingement against the capitellum. The height of the osteotomy must be thoroughly adjusted to bring the radiocapitellar surface of the prosthesis to lay 0–1 mm proximal to the lateral edge of the coronoid process, or preferably according to the anatomy on the uninjured side. Overstuffing, by placing the prosthesis too proud or by choosing too large a diameter head, will place increased stresses on the articular cartilage of the capitellum and sigmoid notch, as well as on the ulnohumeral joint by indirectly disturbing the joint kinematics (Figure 2). Bone cement eases stem fixation in acute cases, especially if there are cracks or small defects in the radial neck. In some (very few) cases the radial neck may be involved in the fracture system, precluding fixation of a short prosthesis stem. In such cases long-stemmed implants should be preferred, even though we believe that long-stem prosthesis extending distal to the 15° angulation
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might create an angular offset from the native radial head. After proper implant insertion, the annular ligament and the radial collaterals are repaired, a suture anchor is convenient for reattaching the ligaments on the lateral humeral condyle. After systematically addressing all the torn columns of the unstable elbow, including the medial and lateral collateral ligaments, it is almost always possible to regain sufficient stability to allow early motion. Proper testing of the joint stability should be performed under fluoroscopic control after wound closure, through the full range of motion. In some rare cases, residual instability will require an additional external stabilizer to allow adequate early motion. Hinged orthotic devices have been advocated, but suffer problems with stable placement of the anatomic hinge of rotation. We find the hinged external fixators more convenient in these cases [15, 42–46]. They maintain concentric reduction of the elbow joint during mobilization, allow exact and stable placement of the rotating hinge and are well tolerated by the patients for the 4–8 weeks that they are generally kept in place (Figure 3).
Rehabilitation The goal for the surgical intervention on the unstable elbow is to establish a congruent and stable joint allowing early movement through the full range of motion. Even so, various regimens for early splinting have been advocated, often involving nighttime extension splinting for the first 6 weeks and a variety of splinting positions between physiotherapy sessions depending on the particular type of instability present [11, 30, 33, 47]. We tend to apply a well-padded splint at the end of surgery, and from the first or second day postoperatively active and active-assisted range of motion exercises are started. Early forearm rotation exercises are also initiated, with the elbow at 90°. As others [15], we believe that active elbow motion enhances stability through recruiting the dynamic muscle stabilizers of the elbow, rather than being detrimental. The last 30° of extension is avoided during the first 3–4 weeks, and no splints or casts are routinely applied in our practice. Indomethacin is prescribed against heterotopic ossification for 4 weeks postoperatively. It should be noted that our active, functional postoperative regimen must not jeopardize the healing of restored bony joint stabilizers. Healing of the fractures should always take precedence over mobilization of the elbow, as chronic instability due to osseous and
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Figures 3a to 3k. A 55-year-old man fell 10 meters down on a concrete floor, injuring his right elbow (a), pelvis and lower extremities. b) Elbow was initially treated with ORIF, and aggressively mobilized in the ICU despite significant residual instability. c) After 8 weeks persistent dislocation and fixation failure were disclosed. d–g) Reoperation with radial head resection and implantation of a cemented, modular radial head replacement (rHeadTM, Small Bone Innovations, Morrisville, Pennsylvania). Due to an osseous defect in the lower capitellum, the prosthesis was stable in flexion only. h–i) Therefore, a hinged external fixator was applied, restoring a stable joint throughout the full range of motion. j–k) After 6 months satisfactory elbow function was restored.
articular deficiencies are notoriously difficult to treat, compared to joint stiffness [16, 48] (Figure 3).
Complications Infections, chronic instability, joint stiffness, heterotopic ossification and secondary arthritis may occur after extensive elbow disruptions, but are not specifi-
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cally related to prosthetic replacement of the radial head. Other complications are specific to the radial head arthroplasty; Silastic implants have shown an increased failure rate as compared with metallic implants, including synovitis, arthritis, and implant fractures [28, 29, 49–51]. Thus, these implants should not be routinely used in elbow trauma. Metal radial head prostheses are less prone to cause synovitis, and
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tolerate the significant loads applied through the radiocapitellar joint. Still, several complications may be attributable to these implants also. Postoperative flexion loss is a major concern [33, 52]. Birkedal and co-workers attributed this to the changes in radiocapitellar gap occurring during flexion-extension movements of the elbow in a biomechanical cadaver study and emphasized the need for attention in addressing the prosthesis fit in elbow flexion as well as in extension [52]. Even though very few studies have specifically addressed the radiocapitellar joint overstuffing, one might suspect this to be a significant problem, with resulting alterations in ulnohumeral joint kinematics and increased contact stresses on the cartilage. Indeed, Van Glabbeek et al.’s cadaver study confirmed that joint kinematics in the unstable elbow was altered significantly by 2.5 mm lengthening or shortening of the radial neck [38]. Clinically, removing the radial head prosthesis may in such cases improve the range of motion [17, 53]. As previously mentioned, a still unsolved issue is the frequent reporting of radiographic loosening of the prosthesis stems in the medium and long terms [31, 33, 54]. These radiographic findings have not clearly been predictive of inferior clinical results. One might speculate that bipolar prosthesis may be especially prone to loosening due to osteolysis caused by polyethylene wear, as in other prosthetic joints, but these speculations are not presently confirmed by available literature.
Conclusions The treatment of radial head fractures continues to challenge orthopedic surgeons. The clinical results of radial head arthroplasty relate to an understanding of the complex elbow injury, and to the proper repair of other important bony and ligamentous stabilizers; the radial head arthroplasty only constitutes a single part of the comprehensive treatment protocol for these difficult injuries. Radial head arthroplasty is indicated in cases with unreconstructable radial head fractures, when radial head resection is likely to induce complications; i.e., in all cases with associated instabilities. Both our choice of implant, surgical technique, and after-treatment is of importance for a satisfactory clinical result in these cases. Whether fixed or loose stem implants, monobloc, modular or bipolar arthroplasties should be preferred is a matter of current discussion, each implant may be associated with specific problems. Independent of implant type attention must be paid to surgical technique, as proper placement of the prosthesis is of utmost importance for
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regaining functional range of motion of the injured elbow. Rehabilitation protocols need to be individualized, but the joint reconstruction must allow early, unrestricted motion. The radial head prosthesis should not simply be considered a spacer; sizing and positioning should be as meticulous as for other joint replacements. References 1.
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38. Van Glabbeek F, Van Riet RP, Baumfeld JA, et al. Detrimental effects of overstuffing or understuffing with a radial head replacement in the medial collateral-ligament deficient elbow. J Bone Joint Surg 2004;86-A:2629–35. 39. Doornberg JN, Linzel DS, Zurakowski D, Ring D. Reference points for radial head prosthesis size. J Hand Surg 2006;31:53–7. 40. Bain GI, Ashwood N, Baird R, Unni R. Management of Mason type-III radial head fractures with a titanium prosthesis, ligament repair, and early mobilization. Surgical technique. J Bone Joint Surg 2005;87:136–47. 41. Dowdy PA, Bain GI, King GJ, Patterson SD. The midline posterior elbow incision. An anatomical appraisal. J Bone Joint Surg 1995;77:696–9. 42. Duckworth AD, Ring D, Kulijdian A, McKee MD, et al. Unstable elbow dislocations. J Should Elbow Surg/Am Should Elbow Surg 2007 Dec 7. 43. Jupiter JB, Ring D. Treatment of unreduced elbow dislocations with hinged external fixation. J Bone Joint Surg 2002;84-A:1630–5. 44. Ring D, Jupiter JB. Compass hinge fixator for acute and chronic instability of the elbow. Oper Orthop Traumatol 2005;17:143–57. 45. Stavlas P, Gliatis J, Polyzois V, Polyzois D. Unilateral hinged external fixator of the elbow in complex elbow injuries. Injury 2004;35:1158–66. 46. Tan V, Daluiski A, Capo J, Hotchkiss R. Hinged elbow external fixators: indications and uses. J Am Acad Orthop Surg 2005;13:503–14. 47. Hotchkiss RN. Fractures of the radial head and related instability and contracture of the forearm. Instr Course Lect 1998;47:173–7. 48. Cobb TK, Morrey BF. Use of distraction arthroplasty in unstable fracture dislocations of the elbow. Clin Orthop Relat Res 1995;312:201–10. 49. Gordon M, Bullough PG. Synovial and osseous inflammation in failed silicone-rubber prostheses. J Bone Joint Surg 1982;64:574–80. 50. Randall T. Surgeons grapple with synovitis, fractures around silicone implants for hand and wrist. JAMA 1992;268:13–8. 51. Worsing Engber RA WD Jr, Lange TA. Reactive synovitis from particulate silastic. J Bone Joint Surg 1982;64:581–5. 52. Birkedal JP, Deal DN, Ruch DS, et al. Loss of flexion after radial head replacement. J Should Elbow Surg/Am Should Elbow Surg 2004;13:208–13. 53. Wretenberg P, Ericson A, Stark A. Radial head prosthesis after fracture of radial head with associated elbow instability. Arch Orthop Trauma Surg 2006;126:145–9. 54. Knight DJ, Rymaszewski LA, Amis AA, Miller JH. Primary replacement of the fractured radial head with a metal prosthesis. J Bone Joint Surg 1993;75:572–6.
Address for Correspondence Prof. Jan E. Madsen Orthopedic Center Ullevål University Hospital 0407 Oslo Norway Phone (+47/22) 11-8080, Fax -9558 e-mail: [email protected]
Eur J Trauma Emerg Surg 2008 Æ No. 2 Ó URBAN & VOGEL
Focus on Elbow Fractures
Radial Head Fractures: Indications and Technique for Primary Arthroplasty Jan E. Madsen1,2, Gunnar Flugsrud2
Abstract The treatment of complex radial head fractures remains a challenge for the orthopedic surgeon. Novel implants and improved surgical techniques have made reconstruction of the radial head with open reduction and internal fixation possible in most cases. However, extremely comminuted radial head fractures with associated instabilities still require replacement of the radial head with a prosthesis to allow rehabilitation with early motion of the elbow, and thereby optimizing the functional results of these potentially devastating injuries. In this article we discuss the surgical considerations related to radial head replacement, encompassing the indications for radial head arthroplasty, implant selection, surgical technique, rehabilitation protocols, and complications related to radial head prosthesis. Key Words Radial head fracture Æ Arthroplasty Æ Radial head prosthesis Eur J Trauma Emerg Surg 2008;34:105–12 DOI 10.1007/s00068-008-8023-y
Introduction Management of radial head fractures requires thorough knowledge of the radial head function in stabilizing the elbow and forearm. Elbow kinematics is complex, with the radial head moving in extension and flexion as well as in rotation of the forearm. Regardless of fracture type, the goals of treatment of the radial head fractures are restoration of elbow stability, preservation of elbow range of motion, and maintenance of the length of the radius. In simple fracture patterns this is accomplished by a short
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immobilization period, followed by early motion exercises. In the complex fracture patterns the clinical decision making becomes more difficult, and needs to be individualized according to the nature of the radial head fracture, associated injuries and each patient’s demands. Historically, radial head resection was the surgical solution in difficult cases of radial head fractures, and may indeed provide reliable pain relief and good range of motion in low– demand patients when associated bone – or ligamentous injuries are absent [1, 2]. However, this is rarely the case, and later reports have outlined inferior results of radial head excision in complex injuries [3–5]. Our ability to fix or replace the radial head after fractures has improved greatly during the last decades, due to improvements of instrumentation and techniques, both regarding internal fixation and radial head arthroplasty. Also, the importance of the radial head as an important elbow and forearm stabilizer has been increasingly emphasized, and understanding of the complex elbow injuries has gradually improved. Thus, in modern decision making, the surgeon needs to decide whether open reduction and internal fixation of the fracture is technically feasible, or whether reconstruction with a radial head arthroplasty is needed.
Understanding the Complex Elbow Injury According to the complex nature of many elbow injuries, and the injury pattern’s impact on treatment, a thorough analysis of each individual injury is of utmost importance for decision making. The main pitfall is to underestimate the associated injuries to the other stabilizing structures of the joint; in the patient with a radial head fracture associated injuries should always be considered.
Faculty of Medicine, University of Oslo, Oslo, Norway, Orthopedic Center, Ullevål University Hospital, Oslo, Norway.
Received: February 11, 2008; accepted: February 18, 2008; Published Online: April 2, 2008
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The radial head is a main contributor to elbow stability and force transmission from the hand to the upper arm. In a cadaver study, Halls and Travill demonstrated that as much as 60% of a load applied to the hand was transmitted through the radiocapitellar joint during resisted flexion, even when the interosseous membrane of the forearm was transected [6]. The force transmission is greatest in extension and pronation, and decreases toward increased elbow flexion. This can result in forces up to 90% of the body weight across the radiocapitellar joint [7]. Furthermore, several studies have confirmed that a radial head resection results in decreased resistance to valgus load of the elbow [8–10], and the radial head is even more essential for elbow stability when there is concurrent damage to the collateral ligaments; In Morrey’s study, radial head resection did not alter the kinematics of an otherwise intact elbow. Release of the medial collateral ligaments caused only a moderate (6–8°) increase in abduction rotation, whereas releasing both lateral and medial ligaments caused gross abduction laxity and elbow subluxation [11]. These findings imply that the implants used for internal fixation, as well as prosthesis used for replacement, must be able to withstand significant loads. And, furthermore, they imply that radial head resection may be an option in comminuted radial head fractures in an otherwise unharmed elbow joint. However, there is a high likelihood of associated injuries to the medial collateral ligaments in patients who have had strong enough forces applied to the elbow to produce extensive comminution of the radial head. And indeed, numerous reports have outlined the potential disadvantages of radial head excision, including decreased grip strength, weak forearm rotation, radial shortening with subsequent wrist pain, and evidence of late arthritic changes [3–5], probably reflecting the high incidence of undiagnosed associated injuries. Due to this, and the fact that modern implants and surgical technique have enabled us to fix or replace most injuries to the radial head, the option of primary radial head resection is very nearly abandoned in our daily practice. To ease decision making, several attempts have been made to classify the injured radial head. Mason’s original classification [12] was put forward in a time when resection or conservative treatment were the only options, and did not account for radial neck fractures, degree of displacement or associated injuries. Today, this classification is of little value in guiding treatment. For this reason, we tend to use Hotchkiss’ modification of the Mason classification
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[13], where type I fractures represent non- or minimally displaced fractures amenable to conservative treatment, type II are displaced fractures technically possible to repair by ORIF, and type III are the severely comminuted fractures judged nonreconstructable by internal fixation. An objection to this classification is that it may have elements of a posthoc treatment – classification, describing a performed treatment without describing the injury’s characteristics or reasons for the choice of treatment. Obviously, with improved implants and surgical technique some of the previous type III fractures are at present fixable, and should be considered type II. The type III fractures then come to include very severely comminuted radial head fractures with resection or replacement as the only treatment options. As associated injuries are common in these cases, and resection hampered with disadvantages, the type III fractures should be treated with radial head replacement. During the last decade standardized surgical protocols for treating elbow dislocations with concomitant fractures have been developed [14–16]. Common to these concepts are early intervention with stable fixation of radial head and coronoid fractures, and repair of torn ligaments to provide sufficient stability to allow early motion. Ring and Jupiter [16], outlined the anatomical restraints of the elbow as components of a ring, with anterior, posterior, medial, and lateral columns or components contributing to stability (Figure 1). This model is very useful in diagnosing and stabilizing the unstable elbow; if one part of the ring (i.e., the radial head) is injured, disruptions of the other columns should always be sought for. During repair, each column is systematically addressed to restore stability. If the radial head is fractured, this involves stable internal fixation if technically possible, or replacement with radial head prosthesis.
Indications for Primary Radial Head Replacement As the radial head is of utmost importance for elbow stability, it should be preserved whenever rigid internal fixation is obtainable [13, 17, 18]. The ability to perform stable fixation of these fractures have improved with time, as both novel implants and improved surgical technique have pushed the limits for what is considered reconstructable, slowly moving the border between type II and type III fractures. Angular stable implants may represent a significant step forward in performing internal fixation of comminuted radial head fractures; superior stability has been proved in a
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Figure 1. The stabilizing structures of the elbow illustrated as a ring [16]. This model invites a systematic approach to diagnosis and treatment of the elbow injuries; if one column is injured (i.e., the radial head), other disruptions should be actively sought for and dealt with to restore joint stability. The injury complexity increases with the number of columns involved. (From: Ring D, Jupiter JB. Fracturedislocation of the elbow. The Journal of bone and joint surgery. 1998 Apr;80(4):566–80. Reprinted with permission from The Journal of Bone and Joint Surgery, Inc).
cadaver study [19], but is not yet verified in clinical trials. Radial head resection should rarely be considered, and only in elderly, low demand patients without associated injuries. Associated ligamentous injuries may be difficult to diagnose, and their recognition and proper treatment are key factors in treating these injuries. The still valid, present indications for primary radial head replacement have previously been summarized [20] to include irreparable radial head fractures in combination with: Any elbow dislocation Medial collateral ligament disruption Lateral ulnar collateral ligament dysfunction Monteggia variants with olecranon fractures
Coronoid process fracture Forearm interosseous membrane disruption (Essex–Lopresti) It should be noted that the irreparable radial head in some cases constitutes a rim fracture, sized >30%. In these cases it is probably better to insert a radial head prosthesis than to leave a significant rim defect, which is likely to lead to recurrent instability. The need for radial head replacement after delayed resection has been questioned [21, 22], and is rarely used in our practice. In cases of early failure of internal fixation in type II fractures, however, radial head prostheses are useful in regaining elbow stability,
Figures 2a and 2b. Overstuffing of the radiocapitellar joint is a common pitfall. This 57-yearold woman sustained a dislocated elbow after falling off her bicycle and an irreparable radial head fracture led to prosthetic replacement. a) The prosthesis is inserted only 1–2 mm too proud compared to the lateral edge of the coronoid process, b) leading to a subtle incongruence of the ulno – humeral joint.
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and good results might be expected in these often difficult cases [23] (Figure 2).
Prosthetic Replacement of the Radial Head Speed reported the first prosthesis to replace the radial head in 1941 [24]. These first arthroplasties were intended to prevent proximal migration of the radius, cubitus valgus and heterotopic ossification. During the next decades, radial head prostheses of different materials were introduced, performing better than the previously used radial head resection. Acrylic implants [25] proved too brittle to support the loads over the radiocapitellar joint, with 2 fractures in 14 patients in Edwards’ series [26]. Swanson introduced the silicone arthroplasty [27], and the silastic implants stayed in vogue for some years, until complications became apparent with fracture of the implants and siliconebased synovitis [28, 29]. Together with experimental studies [8, 9], these findings suggested that silicone prosthesis was not rigid enough to support the lateral column, and they should no longer be routinely used. Presently, a number of metallic radial head prosthesis is available, in various designs [30]. Recognizing that the complex kinematics of the elbow joint is difficult to recreate with a radial head arthroplasty, two different concepts have evolved [31]: 1. A polished stem with a monobloc or modular head, intended to be placed as an intentionally loose metal spacer, or 2. A rigidly fixed stem with a modular or bipolar head. Both concepts have proved better than radial head resection in the unstable elbow, but there is a lack of long-term results in the literature. In Harrington et al.’s work, 16 of 20 patients had a good or excellent result 6– 29 years after treatment for comminuted radial head fractures with associated instability with an intentionally loose polished stem implant [32]. These implants, however, induce radiolucent zones around the stem, as was shown in 17 of 25 patients at an average of 39 months in Moro’s study [33] and later confirmed [31]. The clinical significance of this finding is uncertain. Many authors have favored fixed stem arthroplasties, with press-fit or bone cement fixation. Bone cement is advocated in combined head and neck fractures, and we have found it useful in most fracture cases. Bipolar heads were introduced by Judet in 1996 [34], and have proven good clinical results in the
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medium-term [35, 36]. Even though these bipolar implants may be theoretically advantageous, some concerns exist: In Popovic et al.’s paper, radiographic changes indicating progressive osteolysis around the stem were present in 37 out of 50 patients, mean 8.4 years after the index operation. This finding may be due to polyethylene wear within the stem/head articulation; the polyethylene insert is thin (approximately 3 mm), and the loads transmitted over the articulation are significant [36]. The long-term significance of these findings needs to be addressed in further studies. Whether unipolar, fixed stem prosthesis shows the same evidence of radiographic lucencies in the longterm, is largely unknown. At present we prefer to use a modular, fixed stem implant with a variety of stem sizes, head diameters and head heights (rHeadTM, Small Bone Innovations, Morrisville, Pennsylvania). These implants require minimal neck resections, and allow a fairly close individualization of the prosthesis according to the native size and shape of the radial head. Surgical Technique In the severely injured elbow each injured column is addressed sequentially according to a standardized protocol, as previously described [14–16]. We prefer to position the patient supine, with a tourniquet applied and the injured arm resting on a radiolucent hand table. Even though this is not confirmed in clinical studies, one might expect overstuffing of the radiocapitellar joint to correlate with inferior results [37, 38]. It is therefore of major importance to choose a correct diameter implant, and to perfectly recreate the length of the radius and the position of the radial head relative to the ulna. As there are considerable individual variations in the anatomical relationship between the proximal radius and ulna [39], we use the C-arm in the operating theatre, before the patient is scrubbed, to obtain an exact AP projection of the uninjured elbow. This image later serves as a template for the exact positioning of the radial head prosthesis. AP views of both wrists are also obtained, to rule out, and enable correction for a relative shortening of the radius due to an Essex–Lopresti injury. Skin incisions are chosen according to the pattern of associated injuries. For the radial column a lateral skin incision is preferred. The Kocher interval between the anconeus and extensor carpi ulnaris muscles is used in most cases. When a radial approach to the coronoid process is planned, it may be more convenient to go between the extensor digitorum and extensor carpi radialis muscles. The muscles are retracted to expose
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the lateral ligament complex, which is incised anterior to the lateral ulnar collateral ligament, either in a longitudinal or Z-shaped fashion [40]. In most cases with ulnohumeral dislocations, the radial collateral ligaments are torn off the humeral epicondyle, making the radial approach easy. Coronoid fractures may be approached from the lateral side in anterolateral coronoid fracture patterns, after the humeral head pieces have been removed. If the coronoid fracture is comminuted and includes the ulnar side with the ulnar collateral ligament insertion, a separate, medial approach to the medial column is preferred. The long, posterior skin incision advocated by many authors [16, 33, 41] is well suited with a laterally positioned patient, and especially with severe, associated fractures to the proximal ulna. In the supine position with a structurally intact ulna, we find it easier to use separate medial and lateral incisions. The surgical technique for prosthesis insertion varies according to different implants. After identification and removal of all fracture fragments, and repair of the coronoid process if required, the diameter of the prosthesis is chosen according to the removed head pieces, as close to the native radial head as possible. The radial neck resection is performed according to the implant’s requirements, with or without a resection guide. In general, as little bone as possible should be removed from the radial neck. Mostly, this involves only careful adaptation of the fracture surfaces using bone pliers. Since the exact positioning of the prosthesis is of utmost importance, the direction of the neck osteotomy must be thoroughly adjusted utilizing trial implants; this ensures centering of the implant toward the capitellum, and helps to avoid ‘‘edge binding’’ [30] and impingement against the capitellum. The height of the osteotomy must be thoroughly adjusted to bring the radiocapitellar surface of the prosthesis to lay 0–1 mm proximal to the lateral edge of the coronoid process, or preferably according to the anatomy on the uninjured side. Overstuffing, by placing the prosthesis too proud or by choosing too large a diameter head, will place increased stresses on the articular cartilage of the capitellum and sigmoid notch, as well as on the ulnohumeral joint by indirectly disturbing the joint kinematics (Figure 2). Bone cement eases stem fixation in acute cases, especially if there are cracks or small defects in the radial neck. In some (very few) cases the radial neck may be involved in the fracture system, precluding fixation of a short prosthesis stem. In such cases long-stemmed implants should be preferred, even though we believe that long-stem prosthesis extending distal to the 15° angulation
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might create an angular offset from the native radial head. After proper implant insertion, the annular ligament and the radial collaterals are repaired, a suture anchor is convenient for reattaching the ligaments on the lateral humeral condyle. After systematically addressing all the torn columns of the unstable elbow, including the medial and lateral collateral ligaments, it is almost always possible to regain sufficient stability to allow early motion. Proper testing of the joint stability should be performed under fluoroscopic control after wound closure, through the full range of motion. In some rare cases, residual instability will require an additional external stabilizer to allow adequate early motion. Hinged orthotic devices have been advocated, but suffer problems with stable placement of the anatomic hinge of rotation. We find the hinged external fixators more convenient in these cases [15, 42–46]. They maintain concentric reduction of the elbow joint during mobilization, allow exact and stable placement of the rotating hinge and are well tolerated by the patients for the 4–8 weeks that they are generally kept in place (Figure 3).
Rehabilitation The goal for the surgical intervention on the unstable elbow is to establish a congruent and stable joint allowing early movement through the full range of motion. Even so, various regimens for early splinting have been advocated, often involving nighttime extension splinting for the first 6 weeks and a variety of splinting positions between physiotherapy sessions depending on the particular type of instability present [11, 30, 33, 47]. We tend to apply a well-padded splint at the end of surgery, and from the first or second day postoperatively active and active-assisted range of motion exercises are started. Early forearm rotation exercises are also initiated, with the elbow at 90°. As others [15], we believe that active elbow motion enhances stability through recruiting the dynamic muscle stabilizers of the elbow, rather than being detrimental. The last 30° of extension is avoided during the first 3–4 weeks, and no splints or casts are routinely applied in our practice. Indomethacin is prescribed against heterotopic ossification for 4 weeks postoperatively. It should be noted that our active, functional postoperative regimen must not jeopardize the healing of restored bony joint stabilizers. Healing of the fractures should always take precedence over mobilization of the elbow, as chronic instability due to osseous and
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Figures 3a to 3k. A 55-year-old man fell 10 meters down on a concrete floor, injuring his right elbow (a), pelvis and lower extremities. b) Elbow was initially treated with ORIF, and aggressively mobilized in the ICU despite significant residual instability. c) After 8 weeks persistent dislocation and fixation failure were disclosed. d–g) Reoperation with radial head resection and implantation of a cemented, modular radial head replacement (rHeadTM, Small Bone Innovations, Morrisville, Pennsylvania). Due to an osseous defect in the lower capitellum, the prosthesis was stable in flexion only. h–i) Therefore, a hinged external fixator was applied, restoring a stable joint throughout the full range of motion. j–k) After 6 months satisfactory elbow function was restored.
articular deficiencies are notoriously difficult to treat, compared to joint stiffness [16, 48] (Figure 3).
Complications Infections, chronic instability, joint stiffness, heterotopic ossification and secondary arthritis may occur after extensive elbow disruptions, but are not specifi-
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cally related to prosthetic replacement of the radial head. Other complications are specific to the radial head arthroplasty; Silastic implants have shown an increased failure rate as compared with metallic implants, including synovitis, arthritis, and implant fractures [28, 29, 49–51]. Thus, these implants should not be routinely used in elbow trauma. Metal radial head prostheses are less prone to cause synovitis, and
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tolerate the significant loads applied through the radiocapitellar joint. Still, several complications may be attributable to these implants also. Postoperative flexion loss is a major concern [33, 52]. Birkedal and co-workers attributed this to the changes in radiocapitellar gap occurring during flexion-extension movements of the elbow in a biomechanical cadaver study and emphasized the need for attention in addressing the prosthesis fit in elbow flexion as well as in extension [52]. Even though very few studies have specifically addressed the radiocapitellar joint overstuffing, one might suspect this to be a significant problem, with resulting alterations in ulnohumeral joint kinematics and increased contact stresses on the cartilage. Indeed, Van Glabbeek et al.’s cadaver study confirmed that joint kinematics in the unstable elbow was altered significantly by 2.5 mm lengthening or shortening of the radial neck [38]. Clinically, removing the radial head prosthesis may in such cases improve the range of motion [17, 53]. As previously mentioned, a still unsolved issue is the frequent reporting of radiographic loosening of the prosthesis stems in the medium and long terms [31, 33, 54]. These radiographic findings have not clearly been predictive of inferior clinical results. One might speculate that bipolar prosthesis may be especially prone to loosening due to osteolysis caused by polyethylene wear, as in other prosthetic joints, but these speculations are not presently confirmed by available literature.
Conclusions The treatment of radial head fractures continues to challenge orthopedic surgeons. The clinical results of radial head arthroplasty relate to an understanding of the complex elbow injury, and to the proper repair of other important bony and ligamentous stabilizers; the radial head arthroplasty only constitutes a single part of the comprehensive treatment protocol for these difficult injuries. Radial head arthroplasty is indicated in cases with unreconstructable radial head fractures, when radial head resection is likely to induce complications; i.e., in all cases with associated instabilities. Both our choice of implant, surgical technique, and after-treatment is of importance for a satisfactory clinical result in these cases. Whether fixed or loose stem implants, monobloc, modular or bipolar arthroplasties should be preferred is a matter of current discussion, each implant may be associated with specific problems. Independent of implant type attention must be paid to surgical technique, as proper placement of the prosthesis is of utmost importance for
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regaining functional range of motion of the injured elbow. Rehabilitation protocols need to be individualized, but the joint reconstruction must allow early, unrestricted motion. The radial head prosthesis should not simply be considered a spacer; sizing and positioning should be as meticulous as for other joint replacements. References 1.
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Address for Correspondence Prof. Jan E. Madsen Orthopedic Center Ullevål University Hospital 0407 Oslo Norway Phone (+47/22) 11-8080, Fax -9558 e-mail: [email protected]
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