Flexor tendon injuries in athletes.

REVIEW ARTICLE

Flexor Tendon Injuries in Athletes Julie A. Neumann, MD and Fraser J. Leversedge, MD

Abstract: Flexor tendon injuries are not common in most sporting venues; however, recognition of the pertinent anatomy, clinical findings, and the utility of diagnostic imaging will assist the clinician in a thorough evaluation of the athlete’s hand. Open injuries demand immediate wound care and evaluation as to the integrity of the flexor apparatus; however, closed injuries often present with the challenges of timing: delayed injury presentation and pressures of intervention and return to play. The purpose of this article is to provide a review of the pertinent anatomy of the flexor apparatus of the hand, to identify key aspects of the patient history, clinical evaluation, and diagnostic testing relevant to flexor function, and to discuss treatment options in the setting of injuries to the flexor tendons and flexor pulley system of the hand. Key Words: flexor tendon injury, jersey finger, flexor digitorum profundus tendon, tendon avulsion, pulley injury, climbing injury, athlete injury, sports hand injury

(Sports Med Arthrosc Rev 2014;22:56–65)

within the volar-radial aspect. The FPL tendon is radial and dorsal to the median nerve and, subsequently, it courses in the interval between the thenar muscles and the adductor pollicis muscle toward the thumb.2 In the hand, the lumbrical muscles take their origin from the radial aspect of their respective, but antagonist FDP tendon and course distally, volar to the deep transverse intermetacarpal ligament to contribute to the extensor mechanism of the digit through the oblique fibers of the extensor hood. The anatomic course of the lumbricals is considered as they contribute to flexion of the metacarpophalangeal (MCP) joint and extension of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints based on their relationship to the axis of rotation to each joint.3–5 Understanding the relationship between the FDP and the lumbrical musculotendinous units is essential in explaining the phenomenon of paradoxical digital extension which may occur after flexor tendon injury and repair.

FLEXOR TENDON ANATOMY Knowledge of the anatomic arrangement of the flexor system of the hand is essential for the evaluation and management of injuries to the flexor tendons and retinacular pulleys. Kleinert and Verdan1 described 5 zones of injury (Fig. 1) that consider not only the anatomy of injury, but also reflects the biological mechanisms of repair and functional outcomes. The functioning flexor apparatus of the hand may be considered as a balanced system of intrinsic and extrinsic musculotendinous units. The extrinsic flexor musculature originates in the volar forearm and includes the flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), and flexor pollicis longus (FPL). The FDP arises from the anterior-medial aspect of the ulna and interosseous membrane, often from a common origin, although the index finger may have variable independence. Typically, the FDP to the index and long fingers are innervated by the anterior interosseous nerve and the FDP to the ring and small fingers are innervated by the ulnar nerve. The FDS, innervated by the median nerve, originates from the medial epicondyle of the humerus, the sublime tubercle, and anterior radius and is separated from the deeper FDP muscle by the median nerve which courses distally to the carpal tunnel with the FDS and FDP; the median nerve may be found between the muscle bellies or has been described within the epimysium layer of the FDS. The FPL originates in the mid-forearm on the anterior surfaces of the radius and interosseous membrane and is innervated by the anterior interosseous nerve. At the level of the carpal tunnel, the median nerve is located typically From the Department of Orthopaedic Surgery, Duke University, Durham, NC. Disclosure: The authors declare no conflict of interest. Reprints: Fraser J. Leversedge, MD, Department of Orthopaedic Surgery, Duke University, Durham, NC 27710. Copyright r 2014 by Lippincott Williams & Wilkins

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FIGURE 1. Anatomic zones for the characterization of flexor tendon injuries.

Sports Med Arthrosc Rev

Volume 22, Number 1, March 2014



Flexor Tendon Injuries in Athletes

FIGURE 2. The bifurcating limbs of the FDS tendon rotate laterally and dorsally around the FDP tendon and then divide again into medial and lateral slips. The medial slips cross dorsal to the FDP tendon (decussation), rejoining as the chiasma tendinum of Camper (c) over the distal aspect of the proximal phalanx and PIP joint volar plate. The lateral slip (s) continues distally to insert at the volar base of the middle phalanx. The vincula longum to the profundus tendon (*) is identified as it penetrates the FDS from dorsal to volar Reprinted with permission from r Leversedge et al.2 Copyright [Leversedge FJ, et al.], [Durham, NC]. All permission requests for this image should be made to the copyright holder.

At the distal palm, the FDS splits into 2 limbs, allowing the deeper, or more dorsal FDP tendon to continue to its insertion into the volar base of the distal phalanx. Each diverging limb of the FDS tendon rotates away from the mid-line and contributes a medial slip to the decussating or converging fibers of the chiasma tendinum of Camper (located dorsal to the FDP tendon overlying the proximal phalanx) and a lateral slip to the inserting FDS at the volar aspect of the middle phalanx2 (Fig. 2). The intrinsic contributions to finger flexion include the lumbricals, discussed above, and the interosseous muscles that originate from the metacarpals and act through the transverse fibers of the extensor hood to flex the MCP joint.4,6 Classically, the flexor pollicis brevis has a dual innervation from the median nerve (superficial head) and ulnar nerve (deep head); the muscle originates from the transverse carpal ligament and inserts into the MCP joint capsule and radial sesamoid of the thumb to assist with thumb flexion.2 The fibro-osseous digital sheath begins in the distal aspect of the palm at the approximate level of the metacarpal neck and is continuous to the DIP joint and FDP insertion. The retinacular pulleys are strategically placed condensations of the flexor sheath that provide a biomechanical advantage to flexor function by restricting flexor tendon bowstringing, thus minimizing the work of flexion7–9 (Fig. 3). Serial resection studies evaluating the influence of the various pulleys on tendon function have demonstrated the importance of the A2 and A4 pulleys in the fingers and the A1 and/or oblique pulleys in the thumb, indicating the importance of retaining these pulleys during surgical dissection or reconstructing them in the event of insufficiency.10,11 The flexor tendons are enveloped by the visceral and parietal adventia, or paratenon, a source of nutrition and lubrication for the intrasynovial flexor tendon through a production of synovial fluid.12,13 The relatively hypovascular zone of FDS and FDP tendons within the flexor sheath rely on the nourishing diffusion of synovial fluid within the intratendinous cannaliculi. The flexor r

2014 Lippincott Williams & Wilkins

FIGURE 3. Illustration of the accepted description of the digital flexor pulley system and flexor sheath of the finger.

tendons are nourished also by an intrinsic vascular supply arising from the transverse digital arteries that supply the vincular network on the dorsal surface of the tendons and directly from intraosseous vessels at the tendinous insertions14,15 (Fig. 4). This intrasynovial environment provides www.sportsmedarthro.com |

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Neumann and Leversedge

FIGURE 4. Transverse section of the intrasynovial portion of the digital flexor tendon (clarified after India Ink arterial injection) demonstrating the dorsal vincula or mesotenon. The vincula arise from the transverse digital arterial “ladder” branches and contributes to the nutritional supply of the dorsal flexor tendon. Note the relative hypovascularity of the volar portion of the tendon. Reprinted with permission from r Leversedge et al.2 Copyright [Leversedge FJ, et al.], [Durham, NC]. All permission requests for this image should be made to the copyright holder.

a unique, intrinsic, form of flexor tendon healing during the biological response to injury as compared with the extrinsic mechanism of healing for extrasynovial tendons.12,16

FLEXOR TENDON INJURY Sport-related injuries to the flexor tendon apparatus may be considered as a musculotendinous injury or as a flexor pulley injury, although with any suspected tendon injury it is always important to consider the potential need for pulley repair or reconstruction. Injuries to the FDS, FDP, or FPL tendons are considered to be simple open (laceration), complex open (crush, soft-tissue deficit, tendon injury with associated fracture, and/or neurovascular injury), or closed (avulsion, mid-substance rupture). Obtaining a comprehensive history will assist in determining the mechanism of injury and will help to determine the need for further diagnostic studies and treatment. It is imperative to complete a thorough global assessment of the patient, particularly to establish the presence or absence of associated injuries that might influence overall management.

Closed Flexor Tendon Injuries Closed avulsion injuries or intrasubstance flexor tendon ruptures often occur as the result of eccentric tendon loading. Typically, the patient will describe the forced extension of an actively flexing digit; this injury occurs in the classic scenario of a “jersey finger” whereby the patient grasps onto an opponent’s jersey as the opponent pulls away. Patients may or may not describe feeling a mechanical “pop” associated with tendon failure, and may not appreciate substantial pain or discomfort. Often, the injured finger is slightly swollen and ecchymosis may be visible; these signs may lead the patient to the self-diagnosis of a “sprain” for which immediate evaluation, although preferred, is not pursued (Fig. 5). A loss of active flexion and decreased strength is often the presenting complaint of the patient, and stiffness with attempted digital motion. The ring finger is more susceptible to closed avulsion injury and




FIGURE 5. Typical presentation of a closed, FDP avulsion injury demonstrated in the ring finger. Note the mild swelling and ecchymosis of the distal digit with a characteristic loss of DIP joint tenodesis with the hand in a resting position. Reprinted with permission from r Leversedge et al.2 Copyright [Leversedge FJ, et al.], [Durham, NC]. All permission requests for this image should be made to the copyright holder.

there have been several explanations proposed as to its propensity for injury: (1) the ring finger extends 4 to 5 mm beyond the other fingers during power grip17; (2) secondary to anatomic restraints of both the extensor and flexor systems, the ring finger has the least independent motion of all fingers18–20; and (3) biomechanical studies have indicated that failure strength of the ring finger FDP insertion is less than that of the long finger and that the ring finger absorbs more force than other fingers during pull-away testing, making the ring finger more susceptible to injury.17,21 Closed avulsion of both the FDP and FDS tendon insertions has been reported22,23 and intrasubstance rupture of both FDS and FDP in zone II has been described,24 although these injuries are rare. Most case reports have described such injuries as being associated with a forced hyperextension injury of the digit. In the rare event of a mid-substance flexor tendon rupture, possible pathologic etiologies should be considered. Therefore, this may represent an acute-on-chronic injury mechanism whereby a forcible loading applied to the flexor tendon system, not necessarily one that would cause ultimate failure of the normal tendon, ultimately causes disruption of a compromised tendon. Attritional rupture secondary to fracture or nonunion, such as at the site of a hook of the hamate nonunion,25 or attritional rupture associated with previous hardware implantation and prominence after volar plate fixation of the distal radius26 warrants recognition of the underlying source of degenerative wear, particularly as both of these previous injuries of the wrist are common in athletes. It is important to enquire as to the underlying health conditions, particularly those that might predispose the patient to tenosynovitis or inflammation, such as gout,27 calcium hydroxyapatite deposition disease,28 or inflammatory arthritides, as these conditions may increase the risk of mid-substance tendon rupture or partial rupture.

Open Flexor Tendon Injuries Open flexor tendon injuries such as from a laceration are, in many cases, self-explanatory; however, careful evaluation is warranted. The mechanism of injury and the position of the hand/digit is important in considering both r





the diagnostic evaluation and surgical exposure for repair. In the instance of a laceration, the location of the skin and tendon disruptions are rarely coincidental with one another. Often, the injury (such as with a knife) occurs with the digit in an actively flexed position with the flexor tendon pulled proximally; however, when the digital wound is explored, the hand and digit is placed often in an extended position and the tendon laceration, therefore, is pulled distally with tendon excursion. In the setting of a complex open wound, the mechanism of injury and the on-field management, such as attempted manipulation of an open fracture or dislocation, may influence examination of the involved tendon deficit. Partial tendon lacerations are important, also, as the patient’s history may indicate triggering or locking of the digit with motion, suggestive of tendon triggering or incarceration within the digital sheath during excursion of the flap-like ends of the tendon. Typically, patients with persisting triggering or pain with resisted digital flexion associated with a partial tendon laceration are evaluated at a delayed presentation, once the wound has healed. Obtaining a history of previous treatment, such as wound care and previous wound exploration is useful.

Clinical Evaluation A global patient assessment is critical for managing the injured athlete. Often, hand or digital injuries associated with high-contact sport are completed as a secondary survey or may be associated with a delayed presentation, even after return to play. Evaluation of the injured digit(s) includes inspection of the general appearance of the digit, including skin integrity, vascular status, deformity, and initial observation as to the resting posture of the hand. A lack of tenodesis suggests a loss of continuity of the flexor tendon; this tenodesis may be evident by simple observation and/or with observation of the passive digital motion created with active wrist flexion and extension. In children, this is a useful examination technique, particularly after reassuring the patient by examining the noninjured side first to demonstrate that the injured digit would not have to be manipulated directly. A global neurovascular assessment and palpation for areas of local tenderness, mass, and instability should be completed before the injection of any local anesthetic. Assessment of the integrity of the flexor (and extensor) tendons is done by careful examination based on knowledge of tendon anatomy. Digital tenodesis, as noted above, passive, and active joint motion should be evaluated for each injured digit. Assessment of the FDP tendon is done by holding the MCP and PIP joints in extension and asking the patient to actively flex the DIP joint (Fig. 6). Ability to flex the DIP joint suggests that there is continuity between the FDP tendon and the base of the distal phalanx. Weak or painful flexion can be consistent with an incomplete disruption of the FDP insertion; rarely, the FDP can act to weakly flex the DIP joint through the retained distal vinculum and volar plate29 or a bony avulsion injury that may be trapped at the A5/A4 pulley, creating a flexion moment on the DIP joint. Although the FDP is the only flexor of the DIP joint, it acts to indirectly flex the PIP joint, also. Therefore, to assess FDS function the FDP must be restrained. This is accomplished through the recognition of the common FDP origin and by restricting the FDP to the unaffected digits by holding the digits in full extension, thereby restraining indirectly active excursion of the FDP r


FIGURE 6. Illustration of the clinical examination technique for evaluating active function of the FDP tendon.

to the digit to be tested (Fig. 7). Variations of the FDS to the small finger have been described; the FDS to the small finger may be a hypoplastic or absent in certain individuals and, therefore, may influence the clinical examination.30 In the setting of an open wound, one must consider the possible excursion of the lacerated tendon ends relative to the skin laceration with limb and digital positioning. Therefore, the complete or partial tendon laceration may not be visible within the injury site during limited wound exploration and the examiner must rely on his or her clinical examination and the appearance of the wound to determine whether formal tendon exploration is indicated in the operating room setting. Direct visualization of a disruption of the flexor sheath, hematoma within the flexor sheath, or abnormal tendon motion with attempted active, independent tendon gliding are signs that surgical intervention should be undertaken.

Imaging Studies In general, radiographic evaluation with 3 views of the injured digit(s) is indicated to evaluate for possible tendon avulsion with an associated osseous fragment and/or an associated digital fracture or joint subluxation/dislocation. Careful identification of an avulsion fragment along the flexor sheath, particularly at the volar aspect of the PIP joint, may provide useful information regarding the proximal retraction of a closed tendon avulsion injury. Concern for a pathologic tendon rupture or tenosynovitis, or a www.sportsmedarthro.com |

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TABLE 1. Classification of Flexor Digitorum Profundus Tendon Avulsion Injuries

Type Type Type Type Type

I II III IIIA/IV

Level of Retraction

Prognosis

Palm PIP joint A5/A4 pulley Bone: A5/A4 pulley; tendon: PIP joint or palm

Poor Fair Good Fair/poor

Type I Type I injuries involve a complete avulsion of the FDP insertion and retraction of the tendon and its bony avulsion fragment through the flexor sheath and into the palm. By necessity, the proximal tendon retraction strips the tendon of its vincular attachments, thereby compromising this regional vascular supply to the tendon and removing the tendon from its important intrasynovial environment. Surgery is recommended as soon as possible based on the theoretical compromise of the nutritional source to the tendon, preferably within 7 to 10 days.

Type II

FIGURE 7. Illustration of the clinical examination technique for evaluating active function of the FDS tendon by limiting the indirect action of the FDP tendon.

Type II injuries involve a complete avulsion of the profundus tendon with retraction to the level of the PIP joint. There is less disruption of the vincular system and continuity of the flexor sheath and intrasynovial environment is maintained, thus providing a source of synovial fluid diffusion. Surgery is recommended as soon as possible based on the theoretical compromise of the nutritional source to the tendon, preferably within 7 to 10 days.

Type III delayed tendon injury may be studied with an MRI.31,32 Improvements in the quality and resolution of ultrasound, despite this technique being user dependent, has gained in popularity and may be valuable in assessing tendon continuity or the level of retraction of a transected or avulsed tendon.33

Classification of Injury Tendon laceration: Transection or laceration injuries to the flexor tendons are considered complete or incomplete/partial and are defined by their zone of injury (Fig. 1). The anatomic zones of injury permit perioperative planning by the surgeon, both for repair or reconstructive options and also for the coordination of postrepair rehabilitation. Tendon avulsion: Avulsion of the FDS from its insertion is extremely rare, although it has been described in isolation and in combination with FDP avulsion. Avulsion of the FDP from its insertion at the base of the distal phalanx is more common and is known by the descriptive term “jersey finger.” A classification system for FDP avulsion injuries is pertinent as it emphasizes the variations in both prognosis and treatment choices based on the level of tendon retraction, the remaining sources of nutrition to the avulsed tendon, and the nature of the soft tissue or bony avulsion fragment. The scheme was described by Leddy and Packer18 and included 3 main types of injury (types I, II, and III) and was supplemented by Robins and Dobyns34 through their recognition of a less common, but important type IIIA injury (Table 1).


In type III injuries, the profundus tendon is avulsed from its insertion but retracts no further proximally than the A4 pulley. Proximal retraction of the tendon is sometimes restrained by the vincula and volar plate; however, in the majority of type III avulsion injuries the restriction to proximal retraction is due to a large bony avulsion fragment that is trapped by the A5 or A4 pulleys. In contrast to type I and II injuries, the vinculae and synovial sheath remain in continuity, reducing adverse effects of decreased nutritional sources to the healing tendon. Although surgery is recommended within 7 to 10 days, compromise of the tendon’s nutritional sources is not as severe as in types I and II injuries.

Type IIIA/Type IV Conversion of a type III injury to an unusual type IIIA/type IV injury involves avulsion of the FDP tendon from the bony avulsion fragment after it has been trapped by the flexor pulley system. Proximal retraction of the FDP tendon can, therefore, create an injury comparable with that of a type I or type II injury. The potential for this injury mechanism highlights the importance of confirming the presence of the FDP tendon, attached to the bony avulsion fragment at the time of surgical repair. This injury should not be confused with an FDP avulsion injury that occurs incidentally to a periarticular fracture of the base of the distal phalanx. Surgery is recommended as soon as possible, preferably within 7 to 10 days, based on the theoretical compromise of the nutritional source to the tendon which has retracted proximal to the bony avulsion fragment. r




Injury Management: Prerepair Clinical suspicion for a flexor tendon injury on the field of play is important as the absence of pain or open injury could encourage continued participation, although the risk of further tendon injury is possible with increasing migration of the proximal tendon stump. Conversion of a type II to a type I injury or a type III to a type IIIA injury theoretically creates a poorer prognosis and, therefore, should be avoided by protecting the digit from further injury by application of a forearm-based resting hand-splint application and immediate restriction of activity that might promote further tendon retraction. Open wounds should be treated with appropriate wound management (debridement and irrigation, hemostasis, sterile dressing care), appropriate antibiotic regimen, and tetanus update if indicated.

Injury Management: Surgical Repair General Principles Surgical repair of flexor tendons is done in an operating room setting under a general anesthesia or upper extremity regional block. Depending on the injury, the surgeon (and patient) should be prepared for the potential scenarios of tendon repair and reconstruction, including the need for multiple incisions for tendon retrieval, the potential need for a tendon graft source for pulley reconstruction or primary tendon graft reconstruction, use of a silicone tendon implant, or consideration for salvage procedures in the event that primary repair is not feasible. Preoperative antibiotics are given within 1 hour of incision and tetanus toxoid and/or tetanus immunoglobulin are administered when indicated. Repairs are done using loupe optical magnification. In general, a mid-axial or Bruner-type incision is used to facilitate exposure of the flexor tendon system, although previous incisions or lacerations should be incorporated into the exposure where appropriate, maintaining adequate and viable soft-tissue flaps for subsequent closure. The digital neurovascular bundles are protected and meticulous hemostasis is maintained during dissection. Strategy for the exposure and retrieval of the injured flexor tendons should be considered before opening the digital flexor sheath. A preoperative, high-resolution ultrasound examination may assist in identifying the location of the proximally retracted tendon stump and thus aid with surgical incision planning.35 Preservation of the digital flexor pulleys is important for maintaining optimal biomechanics of the flexor system and the careful handling of the gliding surfaces of the flexor tendons and sheath will reduce the development of peritendinous adhesions that form in response to injury.36 The A2 and A4 pulleys are preserved if possible, although venting of these critical pulleys is reasonable depending on the level of injury and the adequacy of repair. Preserving the adjacent pulleys, therefore, will assist in reducing the work of flexion with venting of the critical A2 and A4 pulleys for tendon exposure. Often, hemorrhage within the sheath identifies the retracted tendon. The tendon may be “milked” distally within the tendon sheath to permit retrieval with the wrist and MCP joints held in flexion or the exposed interior substance of the tendon stump may be grasped using finetoothed forceps. If the tendon stump is not able to be retrieved in an atraumatic manner, then the retracted proximal tendon stump may be retrieved using a pediatric feeding catheter passed retrograde within the flexor sheath r



from the initial wound or at the distal tendon sheath (if avulsion injury) to a transverse incision in the palm or within the membranous portion of the flexor sheath distal to the A2 pulley37 (Fig. 8). As the tendon(s) are retrieved and brought distally for repair, it is important that the FDS and FDP relationship is restored at the level of the FDS bifurcation. Occasionally, the A4 pulley may require sequential dilation using pediatric urethral dilator sounds.

Acute Zone I flexor tendon injuries involving avulsion of the FDP tendon from its insertion or a distal laceration of the FDP tendon with insufficient distal tendon for end-to-end repair are treated by advancement of the proximal stump and reinsertion into the distal phalanx. Generally, up to 1 cm of advancement (although the more independent index FDP may tolerate up to 1.5 cm) may be permissible to avoid the limitations of a postrepair quadriga effect.38 Various methods of repair have been described including: (1) use of a pullout suture passed through osseous tunnels in the distal phalanx and tied over a well-padded suture button placed on the nail (Figs. 9A, B); (2) as for (1), however, the suture is passed around the distal phalanx; (3) suture is tied deep to the skin overlying the extensor tendon insertion after passage from volar to dorsal through transosseous tunnels; and (4) use of suture anchors (Fig. 10).39–43 For each of the repair methods, in general, the distal tendon stump is debrided and the volar base of the distal phalanx, distal to the insertion of the volar plate of the DIP joint, is prepared for tendon reinsertion by debridement of residual tendon fibers and exposure of the phalangeal cortex, although elevation of a periosteal flap may be used. For the pullout button repair method, typically the button and suture are removed at 6 to 8 weeks postoperatively. It is important to inform the patient as to the signs or symptoms of soft-tissue issues while the button is in place as complications are not uncommon.44 Suture anchor use is not without complications, also, as technique-related studies have demonstrated the risk of intra-articular placement and potential dorsal cortical penetration concerning for nailbed injury and/or infection.41–45

FIGURE 8. Intraoperative photograph demonstrating the use of a pediatric feeding catheter to retrieve the retracted FDP stump at the PIP joint after a closed avulsion injury (type II) of the ring finger. Reprinted with permission from r Leversedge et al.2 Copyright [Leversedge FJ, et al.], [Durham, NC]. All permission requests for this image should be made to the copyright holder.

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FIGURE 9. A and B, Intraoperative photograph demonstrating an FDP tendon repair using a well-padded, tie-over suture button (Fig. 8A). Sutures are passed through an osseous tunnel using straight Keith needles that have been drilled through the base of the distal phalanx, maintaining a bridge of approximately 3 mm and avoiding injury to the germinal matrix of the fingernail. The finger is held in flexion as the FDP tendon is reduced to its anatomic insertion and the sutures are secured over the polypropylene button. Note that the digital flexion cascade ideally shows slightly increased tension in the repaired digit (Fig. 8B). Reprinted with permission from r Leversedge et al.2 Copyright [Leversedge FJ, et al.], [Durham, NC]. All permission requests for this image should be made to the copyright holder.

Zone II injuries secondary to open laceration may involve one or both of the flexor tendons. When both tendons are transected, the FDS is repaired first, usually, to reapproximate the inserting limbs of the FDS and its decussating fibers located dorsal to the FDP tendon. Many suture configurations have been described for zone II flexor tendon repair and, although the exact techniques are beyond the scope of this paper, it is important to consider a modern core suture method which is comprised of at least 4 suture strands of 4-0 or 3-0 suture, that interacts with the tendon substance in an appropriate grasping or locking manner, and that is finished with an epitendinous suture repair that not only reduces the tendon ends, but also increases the ultimate strength of the tendon repair construct.36 Treatment of partial tendon injuries should consider the amount of tendon involvement appreciated at the time of open tendon exploration or a patient’s symptoms if there is uncertainty as to the extent of injury during clinical evaluation. Although the difficulty in determining the percentage of tendon involvement in a partial tendon laceration has been demonstrated,46 multiple investigators have concluded that partial lacerations involving 60% should be repaired, typically with a core suture and epitendinous suture repair, as appropriate, to minimize the risk of tendon triggering, entrapment, or rupture.47

Delayed Repair/Reconstruction In the setting of a delayed presentation of flexor tendon injury, consideration for tendon reconstruction should account for the level of injury and the functional goals of the individual. Generally, the time from injury and the level of tendon retraction will determine whether a primary repair can be considered; the retracted tendon stump will alter the length-tension relationship of the musculotendinous unit, resulting in higher risks of contracture with diminished tendon excursion for repair. In addition, a loss of the favorable gliding environment within the “empty” flexor sheath may require a first-stage, recreation of the potential gliding space through the use of a silicone tendon implant. Second-stage flexor tendon reconstruction is delayed until optimal conditions exist for grafting: (1) a supple and mature wound, free of signs of infection or softtissue compromise; (2) maximal recovery of passive digital motion to provide the greatest potential for restoring active motion after tendon reconstruction; and (3) patient compliance with therapy and postoperative care. There are several considerations for reconstructing the flexor tendon–deficient digit. In the finger, patients with an FDP injury but an intact FDS tendon may consider staged flexor tendon grafting; however, procedures that involve excision of the injured FDP tendon (to reduce interference with FDS function) and either DIP joint arthrodesis or DIP joint tenodesis may provide reasonable outcomes.18 Importantly, although these DIP joint stabilization procedures remove the potential for independent FDP function, they are regarded as definitive procedures with consistent results. Typically, the DIP joint is stabilized in neutral or in a slightly flexed position of function. Staged flexor tendon reconstruction, however, typically involve considerable patient investment and commitment with multiple procedures with variable outcomes and, therefore, these factors should be discussed in detail with the patient preoperatively.36 Similarly, in the thumb, reconstruction of the FPL tendon with intercalary grafting, ring finger FDS r




tendon transfer, or interphalangeal joint arthrodesis may be considered in light of the patient’s underlying condition and expectations for recovery of function.

Injury Management: Postrepair Rehabilitation Postrepair rehabilitation protocols have been described elsewhere; however, there are several critical factors: (1) patient education is essential to minimize the risk of postoperative repair site rupture and to maximize tendon function; (2) communication with the patient’s therapist is imperative regarding the nature of the injury and the specific protocol to be used; (3) the timing for the initiation of therapy is ideally between 3 and 5 days to permit immediate postoperative swelling to be reduced to minimize excessive work of flexion; and (4) the use of a low-force, highexcursion protocol will maximize tendon gliding, but minimize the risk of repair site failure.49,50 The indications for flexor tenolysis, typically considered at 3 to 6 months postoperatively, include a failure to regain adequate active and independent tendon gliding for restoring functional activities. This demanding procedure requires close cooperation between the surgeon, therapist, and patient to ensure optimal outcomes.36 The timing for the return to unrestricted activity after flexor tendon repair is not well defined, but should be guided by recognition of the accrual of repair site strength with time and the influence of associated injuries. This might impact the athlete returning from a nonsport-related injury. Generally, release to unrestricted activity is observed to be at between 4 and 6 months from surgical repair, although it is our preference to delay the release to unrestricted activity until 6 months postrepair, similar to the recent recommendations of Ruchelsman et al.51 Despite the good intentions of protective splinting or casting of the injured extremity for return to play, the high risk of repair site rupture persists due to the inability to restrict tensile forces created by the contracting muscle-tendon unit and, therefore, return to upper extremity contact sport and activities involving higher loading forces through the hand and wrist are not advised for 4 to 6 months. Climbing and similar activities/sports that place high tensile loads through the flexor system should be restricted for 6 months from repair. For noncontact athletes and those sports not requiring excessive force through the injured hand and wrist, return to protected activity may be considered at 3 to 4 months. Buddy-strapping of the injured digit to an adjacent digit will reduce the risk of inadvertent eccentric loading or passive extension of the isolated injured digit. A hand-based or forearm-based thermoplastic splint or cast may provide reasonable protection for the healing flexor tendon for noncontact (upper extremity) sports that present low fall risk.

FLEXOR PULLEY INJURY Injury to the flexor pulley system may be caused by a closed or an open injury. Often, the treatment of open injuries are considered in conjunction with flexor tendon injury repair; however, rarely, a longitudinal laceration of the digit may cause isolated injury to the retinacular pulley system and treatment should be considered based on the preservation and/or reconstruction of the A2 and A4 pulleys, as described below. Closed pulley injuries are rare in the general population, but have been described more commonly in rock r



climbers, associated with the high forces placed on the pulley system with the demands of certain climbing maneuvers on the hands, such as with the hanging and crimping positions.52,53 In the hanging position, all of the digital joints are resisting force in a flexed position (MCP, PIP, DIP), whereas in the crimp grip position the DIP joints are hyperextended maximally, the PIP joints are flexed approximately 90 degrees, and the MCP joints are extended. Previous analysis by Lin et al11 demonstrated maximum tear load of the A2 pulley to be approximately 400 N. Biomechanical analyses of forces acting on the A2 pulley with these positions of PIP flexion has demonstrated loads exceeding those calculated by Lin and colleagues, therefore placing the pulley system at risk during this resistance to tendon bowstringing.54–56 The middle and ring fingers are the most prone to injury.54

Clinical Evaluation Generally, patients describe a history of climbing activity and report an acute onset of pain over the volar aspect of the digit, most likely associated with a forceful, irregular movement or slipping from a secure position. There may be swelling and ecchymosis over the local region, depending on the timing from injury. There may be tenderness to palpation of the affected pulley and it may be possible to appreciate the relative tendon bowstringing with resisted finger flexion, particularly compared with a noninjured digit. Local swelling within the flexor sheath may limit digital extension, and a flexion lag may become apparent due to the loss of efficiency of the flexor system.

Imaging Studies In general, radiographic evaluation with 3 views of the injured digit(s) is indicated to evaluate for possible digital fracture or joint subluxation/dislocation. Evaluating a patient for a pulley rupture may be done using MRI, with improved detection using advanced technology.57–60 Although the actual pulley injury may not be visible on MR images, typical findings on T1 sequences include a dehiscence of the tendon from the phalanx and T2 imaging sequences will characteristically highlight local peritendinous inflammation.52 Similar to its increased utility in the diagnosis of flexor tendon injuries, ultrasound has been used in the evaluation of flexor pulley injuries with improving accuracy and may provide the advantage over MRI as being a dynamic study.52,58,59,61

Injury Management: Nonsurgical Treatment In the setting of an isolated and closed pulley rupture, nonsurgical management has become the treatment of choice, supported by both biomechanical studies and outcomes evaluations.52 Generally, initial treatment with antiinflammatory measures, activity restrictions, and emphasis on tendon gliding and range of motion to prevent stiffness or contracture is encouraged. Protective digital taping methods have been advocated in the recovery period, and also with return to climbing activities.62 Such taping methods are advocated, also, in the prevention of injury in higher risk activities.

Injury Management: Pulley Reconstruction Although nonsurgical management is the mainstay of treatment for isolated flexor pulley injuries, multiple pulley ruptures may require surgical reconstruction to restore biomechanical efficiency of the flexor system. Several www.sportsmedarthro.com |

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reconstruction options exist which emphasize the restoration of the biomechanically important A2 and A4 pulleys.63 Consideration of ideal graft sources, such as an extrasynovial tendon (palmaris, plantaris) or intrasynovial tendon (excised FDS, extensor retinaculum) may take into account ease of harvest and resistance to tendon gliding. The A2 pulley reconstruction typically uses a graft passed volar to the extensor tendon apparatus, whereas in the A4 pulley reconstruction the graft is passed dorsal to the terminal extensor tendon. Postoperative protocols include an emphasis on early, independent tendon gliding while avoiding resisted activity that would compromise the pulley repair. Supportive taping or use of a thermoplastic pulley ring is utilized for all activities for 3 months, and with higher loading activities until 6 months postoperatively. Patients are encouraged to continue taping protocols as noted above with any climbing activity in the future.

SUMMARY Flexor tendon injuries in the competitive athlete present similar challenges to those same injuries in noncompetitive athletes or nonathletes; however, with the added complexity of diagnosis, often associated with a delay in presentation, and of the influence of timing from injury to repair, confounded by the desire to return to play which conflicts with the obligate period of tendon healing. In 1948, Pulvertaft,64 a British surgeon, noted that “it is not difficult to suture tendons and prepare the ground for sound union; the real problem is to obtain a freely sliding tendon capable of restoring good function.” His observation some 65 years ago highlights the challenges that we face, even today, with the treatment of flexor tendon injuries. Recent advances in our understanding of the biology of tendon healing hold promise for improved therapies; however, the diagnosis and treatment, and ultimately the outcomes of flexor tendon injuries remain influenced greatly by a comprehensive understanding of pertinent anatomy, the timely recognition and treatment of the condition, and careful patient and therapist education and communication to reduce the risk of adverse events and to maximize tendon gliding capable of restoring good function. REFERENCES 1. Kleinert HE, Verdan C. Report of the Committee on Tendon Injuries (International Federation of Societies for Surgery of the Hand). J Hand Surg Am. 1983;8:794–798. 2. Leversedge FJ, Goldfarb CA, Boyer MI. A Pocketbook Manual of Hand and Upper Extremity Anatomy—Primus Manus. Philadelphia: Wolters-Kluwer/Lippincott Williams & Wilkins; 2010:57–65. 3. Eyler DL, Markee JE. The anatomy and function of the intrinsic musculature of the fingers. J Bone Joint Surg. 1954;36A:1–9. 4. Smith RJ. Intrinsic muscles of the fingers: function, dysfunction, and surgical reconstruction. AAOS Instructional Course Lecture 1975; 200-220. 5. Eladoumikdachi F, Valkov PL, Thomas J, et al. Anatomy of the intrinsic hand muscles revisited. Part II: Lumbricals. Plast Reconstr Surg. 2002;110:1225–1231. 6. Eladoumikdachi F, Valkov PL, Thomas J, et al. Anatomy of the intrinsic hand muscles revisited: part I. Interossei. Plast Reconstr Surg. 2002;110:1211–1224. 7. Doyle JR, Blythe WF. Anatomy of the flexor tendon sheath and pulleys of the thumb. J Hand Surg. 1977;2:149–151.



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48. McGeorge DD, Stilwell JH. Partial flexor tendon injuries: to repair or not. J Hand Surg Br. 1992;17:176–177. 49. Silva MJ, Brodt MD, Boyer MI, et al. Effects of increased in vivo excursion on digital range of motion and tendon strength following flexor tendon repair. J Orthop Res. 1999; 17:777–783. 50. Boyer MI, Gelberman RH, Burns ME, et al. Intrasynovial flexor tendon repair: an experimental study comparing low and high levels of in vivo force during rehabilitation in canines. J Bone Joint Surg Am. 2001;83:891–899. 51. Ruchelsman DE, Christoforou D, Wasserman B, et al. Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg. 2011;19:152–162. 52. Scho¨ffl VR, Scho¨ffl I. Injuries to the finger flexor pulley system in rock climbers: current concepts. J Hand Surg Am. 2006;31:647–654. 53. Schweizer A. Biomechanical properties of the crimp grip position in rock climbers. J Biomech. 2001;34:217–223. 54. Burtscher M, Jenny E. Common injuries with sport mountain climbers. Prakt Sport Trauma Sportmed. 1987;2:15–21. 55. Bollen SR. Injury to the A2 pulley in rock climbers. J Hand Surg Br. 1990;15:268–270. 56. Roloff I, Scho¨ffl V, Vigouroux L, et al. Biomechanical model for the determination of the forces acting on the finger pulley system. J Biomech. 2006;39:915–923. 57. Bodner G, Rudisch A, Gabl M, et al. Diagnosis of digital flexor tendon annular pulley disruption: comparison of high frequency ultrasound and MRI. Ultraschall Med. 1999;20: 131–136. 58. Hauger O, Chung CB, Lektrakul N, et al. Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath. Radiology. 2000;217: 201–212. 59. Martinoli C, Bianchi S, Cotton A. Imaging of rock climbing injuries. Semin Musculoskelet Radiol. 2005;9:334–345. 60. Guntern D, Goncalves-Matoso V, Gray A, et al. Finger A2 pulley lesions in rock climbers: detection and characterization with magnetic resonance imaging at 3 Tesla—initial results. Invest Radiol. 2007;42:435–441. 61. Martinoli C, Bianchi S, Nebiolo M, et al. Sonographic evaluation of digital annular pulley tears. Skeletal Radiol. 2000;29:387–391. 62. Scho¨ffl I, Einwag F, Strecker W, et al. Impact of taping after finger flexor tendon pulley ruptures in rock climbers. J Appl Biomech. 2007;23:52–62. 63. Seiler JG III, Leversedge FJ. Digital flexor sheath: repair and reconstruction of the annular pulleys and membranous sheath. J South Orthop Assoc. 2000;9:81–90. 64. Pulvertaft RG. Repair of tendon injuries in the hand. Ann R Coll Surg. 1948;3:3–14.

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Extensor tendon injuries in athletes.

Update on Zone II Flexor Tendon Injuries.

Flexor tendon injuries in children: Rehabilitative options and confounding factors.

Zone III flexor tendon injuries - A proposed modification to rehabilitation.

Pediatric flexor tendon injuries: A 10-year outcome analysis.

[Management of zone 1 flexor digitorum profundus tendon injuries].

[Isolated injuries of the pulley of the finger flexor tendon sheath--injuries in extreme climbing sports].

Closed flexor tendon ruptures.

Digital flexor tendon irrigation.

A nitinol based flexor tendon fixation device: gapping and tensile strength measurements in cadaver flexor tendon.

Evidence-based flexor tendon repair.

Achilles tendon injuries in elite athletes: lessons in pathophysiology from their equine counterparts.

Flexor tendon lacerations in zone V.

Flexor tendon forces: in vivo measurements.

MUSCLE INJURIES IN ATHLETES.

Partially Divided Flexor Tendon Injuries: Should They Be Repaired or Not?

A 'haematoma sign' in flexor tendon injury.

Protecting flexor tendon repair in preschool children.

Different distributions of operative diagnoses for Achilles tendon overuse injuries in Italian and Finnish athletes.

[Distal biceps tendon injuries -- injuries of the distal biceps tendon].

Spontaneous flexor tendon rupture in the palm.

Staged flexor tendon reconstruction in children.

Exertion injuries in adolescent athletes.

Overuse injuries in adolescent athletes.