Stener Lesion Treatment & Management


Practice Essentials

A Stener lesion occurs when the thumb is forcefully abducted and the distal attachment of the ulnar collateral ligament (UCL) at the metacarpophalangeal (MCP) joint is traumatically avulsed from its insertion into the base of the proximal phalanx of the thumb. [12The avulsed end of the UCL gets caught under the proximal edge of the adductor aponeurosis and folds into itself as the thumb returns to its normal position. The displacement of the avulsed UCL from its insertion ultimately results in thumb MCP joint instability to valgus stress.

In his now classic 1962 article, Stener described a distinct, surgically correctable anatomic lesion that could account for the chronic instability found in the thumbs of some gamekeepers and skiers. [3 Campbell first coined the term gamekeeper's thumb in 1955, when he described insufficiency in the UCL of the thumb MCP joint in many Scottish gamekeepers. [4]

The proposed etiology of this laxity was related to the method used by gamekeepers to kill wounded rabbits. A gamekeeper would hold the rabbit's legs in one hand and wedge the animal's neck in the cleft between the thumb and index finger of the other hand. By forcefully pulling on the rabbit's legs, the neck was stretched and extended against the ulnar side of the thumb, thus breaking the neck and killing the rabbit. The multiple repetition of this maneuver was thought to be the cause of the UCL laxity found in 20 of the 24 Scottish gamekeepers examined in Campbell's study.

More than a decade earlier, acute rupture of the UCL of the thumb as a result of major trauma was reported in Europe. European authors made the correlation between downhill skiing and this injury, coining the term skier's thumb. The proposed mechanism of injury was a traumatic avulsion of the UCL from forced abduction of the thumb proximal phalanx. This forced abduction occurred from falling on the outstretched hand while still holding a ski pole. Any extreme valgus stress on the thumb can result in a ligamentous disruption of the UCL. The most common mechanism is a fall on the abducted thumb.

Stener observed and reported several cases in which a distal rupture of the UCL of the thumb MCP joint occurred, with interposition of the adductor aponeurosis between the distal site of attachment of the ruptured ligament and the detached ligament. The interposed adductor aponeurosis maintains separation between the ruptured ends of the ligament and thus prevents ligamentous healing and restoration of joint stability.

Little controversy exists regarding the need for operative intervention for a true Stener lesion. As with any surgical procedure, however, surgeon-dependent variations exist with respect to operative technique and postoperative protocol.

Anatomy

The clearest and most eloquent anatomic depiction of the Stener lesion can be found in Stener's 1962 article. [3Most of the material included here is adapted from his original work.

Important structures around the MCP joint include the adductor aponeurosis and tendon, the dorsal aponeurosis, the collateral ligament proper, and the accessory collateral ligament of the thumb. The adductor aponeurosis serves as an active restraint to thumb abduction but has no passive role in MCP stability. Severance of the adductor aponeurosis has no effect on lateral stability.

The UCL of the thumb is composed of two discernible components, the accessory and the proper. In his cadaveric dissections, Stener found that the UCL proper was taut in flexion and loose in extension, whereas the opposite was true for the accessory UCL. Transection of the UCL proper resulted in increased abduction when the MCP joint was flexed but not when the joint was held in the extended position. This instability was found to be slight and did not become severe until the accessory UCL was severed as well. The volar plate restricted abduction when the MCP joint was extended, even when both the UCL proper and the UCL accessory were severed.

The UCL provides lateral support and prevents volar subluxation of the MCP joint. Stability of the thumb MCP joint to abduction is vital for key pinch, tip pinch, and thumb opposition.

Pathophysiology

Stener described a lesion produced by forced thumb abduction in which the distal attachment of the UCL was traumatically avulsed from the proximal phalanx of the thumb. The severed end would become caught under the adductor aponeurosis and therefore be unable to return to its anatomic position. Consequently, the severed ligament would fold on itself and thus be prevented from healing and restoring stability to the MCP joint (see the image below).

Displacement of the ulnar collateral ligament by tDisplacement of the ulnar collateral ligament by the adductor aponeurosis during hyperabduction of the thumb.

With a Stener lesion, a situation exists in which the MCP joint of the thumb is rendered permanently unstable because the UCL is prevented from healing by the interposed adductor aponeurosis. The resultant chronic instability significantly impairs function in the injured hand.

Prognosis

Stener's original article was a significant contribution to the treatment of acute disruptions of the UCL of the thumb MCP joint. If a Stener lesion is recognized early, the UCL may be reduced operatively and secured in its anatomic position. Early recognition and anatomic reduction can result in excellent functional outcome in the vast majority of cases. Late presentation or a delayed diagnosis of a Stener lesion may produce a need for more involved surgery, with less desirable results.



History

A patient with an acute injury to the ulnar collateral ligament (UCL) presents with a painful, swollen, ecchymotic thumb metacarpophalangeal (MCP) joint. The physician must differentiate between an incomplete rupture or sprain and a complete rupture of the UCL. If a complete rupture is suspected, the physician must differentiate between a complete rupture with adductor aponeurosis interposition (Stener lesion) and a complete rupture with anatomic or near-anatomic positioning of the severed end of the UCL.

Physical Examination

Before the stress-testing part of the physical examination, plain anteroposterior (AP) and lateral radiographs are obtained. Valgus stress testing prior to radiographic evaluation may be contraindicated in the case of a nondisplaced ligamentous or avulsed bone fragment. [5Such a maneuver theoretically could turn a nondisplaced disruption into a displaced Stener-type lesion.

A protocol and classification system developed by Louis et al in 1986 [6provides a systematic method of evaluation for the acute UCL injury. In this system, radiographs are used to classify the ligamentous injury into one of the following five categories:

  • Type I (nondisplaced avulsion injury)
  • Type II (displaced fracture of the ulnar aspect of the base of the proximal phalanx)
  • Type III (ligament strain)
  • Type IV (complete UCL tear)
  • Type V (avulsion of the volar plate, with no UCL injury)

If no fracture fragment is seen on initial radiographs, assessment of MCP stability to passive radial deviation is attempted. The MCP joint should be in a flexed position for testing, with the examiner firmly grasping the metacarpal head with one hand and passively applying a radial force to the proximal phalanx with the other hand (see the image below). If pain precludes examination, a local anesthetic may be used.

Stress view of ulnar collateral ligament. Stress view of ulnar collateral ligament.

If resistance is felt as the thumb is radially deviated less than 35°, the patient most likely has a type III ligament injury. In a type IV injury, the thumb deviates radially more than 35° as it is stressed. A type IV injury should be treated surgically, in that it may reflect the presence of a Stener-type lesion. A type V injury easily may be mistaken for a type II injury when it is associated with an avulsion fracture. A type V injury is stable in flexion and is treated with a thumb spica splint or cast for 4 weeks

Palpation of a lump (the distal end of the ruptured UCL) on the ulnar aspect of the thumb MCP joint is strongly suggestive of a Stener lesion; however, the absence of a mass does not exclude a Stener lesion.

Diagnostic Considerations

Early diagnosis of an acute Stener lesion is important, in that repair of the ulnar collateral ligament (UCL) is more difficult when treatment is delayed longer than 3 weeks. More complex ligament reconstruction procedures (eg, adductor tendon advancement and arthrodesis) may be necessary when treatment of an acute UCL injury is delayed. Long-term instability may lead to traumatic degenerative joint disease and could necessitate arthrodesis for definitive treatment.



Imaging Studies

Radiography

Anteroposterior (AP) and lateral radiographs are used to classify the ligamentous injury into one of five types in accordance with the schema developed by Louis et al (see Presentation).

Other imaging modalities

Other methods of diagnosis, such as stress radiography, magnetic resonance imaging (MRI), [8arthrography, and ultrasonography (US), [9also have been used to aid in diagnosing Stener lesions, with varying accuracy. Further research is needed to delineate the accuracy of these modalities. [10111213141516]

Melville et al, in a retrospective study aimed at characterizing the  appearance of surgery-proven displaced UCL tears on US, determined that two US findings—the absence of UCL fibers and the presence of a heterogeneous masslike abnormality proximal to the first MCP joint—were 100% accurate in differentiating displaced from nondisplaced full-thickness tears of the thumb UCL. [17]

The so-called tadpole sign on US has been described as representing a Stener lesion. [18]

Milner et al used extremity MRI to assess UCL injury and measure the degree of ligament displacement, which they then correlated with clinical outcome; planned surgical intervention was reserved for patients with a Stener lesion. [19They were able to generate a four-stage treatment-oriented classification of these injuries, as follows:

  • Type 1 (partial and minimally displaced UCL tears (type 1) - Typically healed with immobilization alone
  • Type 2 (tears displaced < 3 mm) - Typically healed by immobilization alone
  • Type 3 (tears displaced >3 mm) - Failed immobilization and required surgery in 90% of cases
  • Type 4 (Stener lesion) - Failed immobilization and required surgery in all cases


Approach Considerations

Stener was able to identify a subgroup of individuals with a ulnar collateral ligament (UCL) injury who required operative intervention for the restoration of UCL integrity and, therefore, metacarpophalangeal (MCP) joint stability. [3]

If the adductor aponeurosis is interposed between the ruptured ends of the UCL, only operative intervention will allow apposition and healing of the traumatically displaced ligament in an anatomic position. If a Stener lesion is not present, splinting of the thumb in such a way that the torn ligament ends are reduced may lead to ligamentous healing and restoration of joint stability in select patients. The ligamentous injuries may also require surgical treatment.

Medical Therapy

Closed treatment is satisfactory for type I, III, and V injuries. Immobilization in a thumb spica cast for 4 weeks usually is sufficient. Type II and IV injuries are unstable and require operative treatment. [71320]

Surgical Therapy

Operative exposure and repair

In 1994, Kozin and Bishop [21 described the following operative method of exposure and repair of the Stener lesion:

  • A chevron or S-shaped incision is made over the dorsum of the thumb MCP joint, with the apex at the thumb-index webspace
  • The skin flap is elevated, with care taken to preserve any superficial radial nerve branches
  • At this point in the dissection, the displaced UCL may be observed at the proximal edge of the adductor aponeurosis; if the ligament is disrupted and displaced, it should be seen in cross-section, held in a displaced position by the proximal edge of the adductor aponeurosis
  • The adductor aponeurosis is incised longitudinally, parallel and just ulnar to the extensor pollicis longus (EPL) tendon, and then elevated from the underlying capsule
  • The adductor aponeurosis then is retracted distally, and a longitudinal capsulotomy is performed if one did not occur at the time of the avulsion injury

The UCL frequently is torn from the insertion site at the proximal phalanx (see the image below), sometimes with an avulsed bony fragment attached. [13A midsubstance tear may be repaired with a 3-0 nonabsorbable suture.

Ruptured ulnar collateral ligament. Ruptured ulnar collateral ligament.

If the UCL is avulsed from the distal insertion site, the distal insertion site on the proximal phalanx is roughened and prepared for reattachment of the ligament. The ligament is reattached with a suture anchor or a pullout suture with a nonabsorbable suture (see the image below). The MCP joint then is pinned with a 0.045-in. Kirschner wire (K-wire) in approximately 20° of flexion and with slight ulnar deviation prior to suture tying.

Completed repair using suture anchors for fixationCompleted repair using suture anchors for fixation.

The volar plate is repaired to the reinserted UCL to restore accessory UCL function. The pin is removed at 5 weeks, when the thumb spica cast is removed, and active motion is instituted. Abduction stress is avoided for approximately 3 months.

Surgical exposure is similar when a substantial fracture fragment (type II) is identified with the avulsed UCL. Tension band fixation of the small fragment then is used so that the fracture fragment is reduced but not fragmented. Blood supply to the fragment is maintained and prominent hardware is avoided with this fixation method.

A 26- or 28-gauge steel wire is passed in a figure-eight fashion through a predrilled hole in the proximal phalanx and at the collateral ligament insertion into the bony fragment. Tightening of the figure-eight tension band construct provides for secure fixation, reconstitution of articular congruity, and restoration of normal ligament length. Other authors have described tying the suture over a button on the radial side of the MCP joint with a pullout suture technique, but this method leaves exposed suture and a looser repair than does the aforementioned method.

The most critical aspect of the repair, regardless of the technique utilized, is anatomic restoration of the ligamentous attachment in the proper orientation. In thumbs treated acutely (< 3 weeks from injury), a good-to-excellent result can be expected in more than 90% of cases, regardless of ligament repair technique. [20]

Chronic ligamentous injuries (>3 weeks from injury) are difficult to repair primarily. If significant arthritis is present, arthrodesis of the MCP joint decreases pain, increases stability, and improves thumb function. If arthritis is not present, adductor tendon advancement or ligamentous reconstruction may be attempted for reconstruction of the unstable MCP joint. An adductor advancement consists of relocating the adductor insertion distally to increase stability. The UCL also may be mobilized, and an attempt at repair can be made as well. [22]

Ligament reconstruction with a free or local tendon graft has been described using various ligaments. The palmaris longus is the most common choice; other, less common choices include the extensor pollicis brevis (EPB) tendon, the plantaris, a toe extensor, a slip of the abductor pollicis longus (APL), and a portion of the flexor carpi radialis (FCR) tendon.

In the case of a palmaris longus free-tendon graft, the tendon is harvested and then passed through a tunnel in the metacarpal head from dorsal to palmar. Finally, it is attached to the proximal phalanx. Analysis of outcome using this technique has indicated that it provides adequate stability with some loss of motion.

Complications

Complications associated with surgical repair of an acute UCL injury include radial sensory nerve neurapraxia, stiffness of the thumb interphalangeal (IP) and MCP joints, and, infrequently, recurrent instability.


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