Flexor Tendon Injuries

Avulsion of Flexor Tendon Profundus

Avulsion of the flexor digitorum profundus at its insertion on the distal phalanx is known as jersey finger. This is commonly seen in football, rugby, or flag football and usually results from grasping the pants or jersey of an opposing player. As the player pulls away, the finger is forcibly extended while the profundus continues to contract and avulsion may result. McMaster,91 in 1933, showed experimentally that a normal tendon ruptures most commonly at its insertion, less commonly at the musculo-tendinous junction, and rarely in the substance of the tendon.

Although any digit may be involved in profundus avulsion, the ring finger is most commonly affected. This is likely because the insertion of the profundus in the ring is anatomically weaker than that of the surrounding fingers and frequently the small finger slips away when grasping an opponent's jersey, leaving the ring finger to bear the brunt of the forces.92 Profundus avulsion injuries frequently go undetected in acute stages, resulting in a delay in diagnosis and treatment, which may adversely affect the end result.

On examination, the diagnosis may be apparent by the relative position of extension of the digit. The function of the pro-

fundus and sublimis tendons must be specifically tested individually (Fig. 41-26). The amount of soft-tissue swelling should be noted and precise localization of the tenderness is very important in an attempt to identify the level of retraction of the avulsed tendon. Leddy and Packer92 classified profundus avulsion into three main categories: type 1 in which the tendon retracts to the palm, type 2 in which the tendon retracts to the PIP level, and type 3 in which a bony fragment is avulsed with the tendon. It is important to try to ascertain by physical examination and radiograph studies which type is present.

Tendon nutrition has been studied extensively, and there appears to be a dual supply of nutrients to tendons within the sheath consisting of a vascular profusion and diffusion from synovial fluid from within the sheath.93 Potenza,94 in 1963, showed that diffusion of nutrients from the synovial fluid occurs and contributes significantly to tendon nutrition. The most important consideration in determining treatment of profundus avulsion are the level of tendon retraction, the remaining nutritional supply to the tendon, the length of time between diagnosis and treatment, and the presence of a bony fragment.95

Small Finger Flexor Tendon Repair

Figure 41-26 A, Testing of the flexor digitorum profundus. The intact profundus tendon actively flexes the distal interphalangeal joint. B, Testing the flexor digitorum superficialis, which actively flexes the proximal interphalangeal joint. The profundus unit is inactivated by passive extension of the other fingers.

Figure 41-26 A, Testing of the flexor digitorum profundus. The intact profundus tendon actively flexes the distal interphalangeal joint. B, Testing the flexor digitorum superficialis, which actively flexes the proximal interphalangeal joint. The profundus unit is inactivated by passive extension of the other fingers.

Type 1 usually reflects the most severe injury as the blood supply from the vincular system is disrupted and the diffusion pathway is not functional. The tendon must be reinserted within 7 to 10 days following injury or it will become retracted and nonrepairable.

In type 2 injury, the tendon retracts to the PIP joint and is held there by a long vinculum attachment. Presumably because of the intact profusion to the vinculum and the fact that the tendon remains in its sheath, nutrition through profusion and diffusion is relatively intact. On examination, tenderness is usually maximal at the PIP joint and no palmar mass is palpable, thus differentiating it from type 1. Optimal treatment of type 2 is by early repair, but repair may be delayed 3 to 6 weeks or even as long as 3 months according to Leddy.95 It should be remembered that it is possible for a type 2 to convert to a type 1 on a delayed basis, particularly in the case of an athlete completing the season prior to repair.

In type 3, the avulsed bony fragment is usually trapped by the A-4 pulley, preventing proximal retraction. Here tendon nutrition is preserved and delayed repair is usually possible. However, one should be aware of cases in which the fragment is trapped by the A-4 pulley but the tendon avulsed from the fragment, producing a type 1 situation.

Following repair, the wrist should be ulnarly splinted with the wrist slightly flexed and MCP joints in 50 to 60 degrees of flexion and interphalangeal joints in relative extension. Passive ROM exercises may be started within the first few days, and splinting continues for 4 to 5 weeks. If pull-out suture is used, it is removed at 4 weeks and intermittent splinting begun. Repair may also be performed by mini suture anchors, although the traditional pull-out wire is still favored by most.

If the athlete is involved in a sport in which grasping is not essential, return to competition within 2 weeks is possible with the use of a mitten-type splint or playing cast with the wrist in neutral or slight flexion with the digits flexed into the palm in the fisted position. The patient should not be allowed maximum gripping activities for 10 to 12 weeks after repair. This should always be explained in detail to the athlete and his or her family, as competing too soon after repair carries a definite risk of rerupture.

In considering treatment options for in-season athletes, all should be informed that best results are obtained from early repair regardless of the level of tendon retraction. At the high school level, we recommend early repair in most cases as career requirements are unknown and the goal is to restore normal DIP joint function. In higher levels of competition (college or professional), we discuss in detail the option for delayed repair in certain cases. Most professional athletes opt to be treated without early repair, while the collegiate athlete's desires vary according to career plans.

Many profundus avulsions are seen at a time remote from the injury. At this time, treatment options include delayed primary repair in types 2 and 3 if the injury is less than 3 months old, neglect in cases in which symptoms are minimal, excision of the retracted tendon in the palm if painful, arthrodesis of the DIP joint in cases in which the DIP is unstable or recurrent dorsal dislocation occurs, or a tendon graft through the intact sub-limis.92,96 In our experience, most athletes are not symptomatic enough to require any of the preceding procedures except occasionally excision of the tendon in the palm. The PIP joint usually functions quite normally in these patients, and the goal of independent profundus function in the ring finger is frequently not necessary except in musicians and other highly skilled professionals.

Rupture of the flexor profundus of the small finger in the palm has been reported by Stark et al,97 secondary to nonunited hook of the hamate fractures. This should be considered in the differential diagnosis of athletes presenting with isolated small finger flexor digitorum profundus rupture particularly if the sport involves use of a bat, racquet, or golf club. In Stark et al97 series, two cases of flexor tendon rupture in 62 cases of hook of the hamate fracture were noted. Bishop and Beckenbaugh98 found a 25% incidence of tenosynovitis, tendon fraying, or rupture in a series of hook of hamate fractures. The tendon damage is produced as it glides against the rough bony surface of the fracture of the hook. Base fractures are more commonly associated with tendon injuries.

Diagnosis may be made clinically by demonstrating the inability to flex the DIP joint of the small finger as well as noting tenderness over the hook of the hamate. Fractures may be well demonstrated by supinated carpal tunnel views on radiographic examination or computed tomography scan. Tendon rupture may be apparent on magnetic resonance imaging. Treatment of the tendon rupture, if isolated to the flexor digitorum profundus of the small finger, may be accomplished by transfer of the flexor digitorum sublimis of the ring finger or side-to-side repair to the adjacent profundus to the ring. If multiple tendons are ruptured, primary repair may be considered, although frequently a bridge graft using flexor digitorum sublimis or free tendon graft is necessary.

Although quite rare, Schnebel et al99 reported a case of isolated traumatic avulsion of the flexor digitorum sublimis in a college football player. Several previous cases were reported in the literature that were treated without surgical intervention, although in one case presenting with pain and loss of extension at the PIP joint, the sublimis was excised and synovectomy performed.

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  • jolanda
    Who is more likely to get a flexor tendon injury?
    4 months ago

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