Thumb Metacarpophalangeal Ulnar and Radial Collateral Ligament Injuries





Thumb metacarpophalangeal collateral ligament injuries are common in athletes and occur via forced abduction or hyperextension. Management primarily depends on the grade of ligamentous injury and the presence of a Stener lesion or large avulsion fracture. Surgeons should consider the athlete’s position, hand dominance, duration of season remaining, and goals. Shared decision making regarding timing of surgery is imperative. Acutely, primary ligamentous repair with or without augmentation is achievable. Chronic collateral ligament injuries are effectively treated with ligament reconstruction. Numerous surgical techniques have been described without 1 showing superiority. Postoperative rehabilitation protocols vary based on repair quality and sports-specific considerations.


Key points








  • Ulnar collateral ligament (UCL) and radial collateral ligament (RCL) have an accessory and proper component.



  • Grade I or II and certain grade III UCL injuries can be managed with nonoperative immobilization with good long-term results.



  • Grade III UCL injuries with a Stener lesion and avulsion fractures involving greater than 30% of the articular surface are best treated with surgery.



  • Treatment considerations need to take into account the level of athletic participation, hand dominance, demands on the thumb during the athlete’s respective sport, the practicality of playing with thumb immobilization, the duration of season remaining, and patient’s/athlete’s specific goals.



  • There are various methods of repair and reconstruction of both UCL and RCL injuries with comparable outcomes.




Introduction


Thumb metacarpophalangeal (MCP) joint collateral ligament injuries are among the most common injuries to the hand. Previous reports show an incidence of collateral ligament injuries as high as 86% of the injuries to the thumb. , These injuries are especially common in athletes. Ulnar collateral ligament (UCL) injuries occur 10 times more frequently than radial collateral ligament (RCL) injuries. UCL injuries occur via thumb MCP hyperabduction or hyperextension ; in contrast, RCL injuries result from a forced or sudden thumb MCP adduction moment. Of note, complete injury of either the UCL or RCL can lead to MCP instability; disability; future degenerative changes; and, in athletes, missed time from play.


An acute UCL injury, often termed a skier’s thumb because of its high prevalence in the sport, occurs secondary to a fall onto an outstretched hand with the abducted thumb around the ski pole imparting a significant valgus stress to the thumb MCP joint. An 11-year study out of a Wyoming ski resort found that 7% of all injuries sustained were related to UCL injuries about the thumb. Other studies report UCL injuries to be the second most common ski injuries behind medial collateral ligament injuries of the knee. A chronic UCL injury is termed gamekeeper’s thumb, which was found to be a common attritional rupture of the UCL in Scottish gamekeepers.


Thumb collateral ligament injuries are a frequent injury found in the National Football League (NFL). In a review of 10 years of injuries in the NFL, nearly one-third of all hand injuries involved the thumb, with 25% of those affecting the MCP joint. In collegiate football, the subsequent impact of these injuries to the athletes resulted in approximately 3 weeks’ loss of playing time.


Anatomy


The thumb MCP joint is a diarthroidal joint with motion primarily in the sagittal plane allowing flexion and extension but also some degree of abduction, adduction, and circumduction. Stability of the thumb MCP joint is provided through both static and dynamic restraints. Static stabilizers include the bony anatomy of the MCP joint, the RCL and UCL, volar plate, and dorsal capsule. Dynamic stabilization is provided by the extrinsic and intrinsic muscles of the thumb crossing the MCP joint. Of the intrinsic muscles, the adductor pollicis is the most pertinent to the thumb’s MCP joint stability as it resists valgus forces.


The UCL and RCL each consist of a proper and accessory collateral ligament, traveling in a proximal-dorsal to distal-volar direction. Cadaveric studies have shown that the UCL, on average, originates 4.2 mm from the dorsal surface and 5.3 mm proximal to the articular surface of the metacarpal head, and inserts 2.8 mm from the volar surface and 3.4 mm distal to the base of the proximal phalanx. The proper collateral ligament runs approximately 30° in a dorsal to volar trajectory to insert at the base of the proximal phalanx. The accessory collateral ligament is volar to the proper collateral ligament, and inserts on the volar aspect of the proximal phalanx and volar plate at an approximately 90° trajectory from its origin. With the MCP in approximately 30° flexion, the proper collateral ligaments and dorsal capsule provide stability to radial and ulnar deviation of the thumb MCP joint; therefore, this is the optimal position for testing the integrity of the proper UCL and RCL. With the MCP in full extension, stability is provided primarily by the accessory collateral ligament and volar plate. The UCL is important in MCP joint stability and is critical for gripping, key pinch, and activities of daily living. It also provides resistance to volar subluxation. , In addition, the RCL and UCL accompany the dorsal capsule in providing dorsal support to the MCP joint.


Variation exists in the population regarding the morphology of the thumb MCP joint, with round and flat types having been described. The different morphology types have been linked to MCP joint range of motion as well as to the mode of failure of the UCL. Rounder MCP joint morphology shows increased range of motion with concomitant greater elasticity and creep before load to failure. In contrast, a flatter morphology has less range of motion and less creep before load to failure.


Forced palmar abduction (radial deviation) at the thumb MCP joint may injure or rupture the UCL, with avulsion off the proximal phalanx occurring in approximately 90% of cases. In addition to the collateral ligament injury, the dorsal capsule and/or volar plate can also be injured, leading to volar and radial subluxation of the proximal phalanx. This subluxation is secondary to the pull of abductor pollicis brevis (APB) and flexor pollicis brevis. , , The UCL most commonly tears at the distal insertion either as an avulsion or purely ligamentous injury, although proximal avulsions and midsubstance tears are described, most likely because the UCL is narrower distally than proximally. The abduction force can be significant enough to displace the torn UCL ligament superficial to the adductor aponeurosis, creating the eponymous Stener lesion ( Fig. 1 ). A Stener lesion has been noted to occur in 60% to 90% of cases and portends a poorer prognosis without operative treatment. ,




Fig. 1


UCL injury showing intraoperative Stener lesion.


On the radial side of the thumb MCP joint, the average footprint of the RCL origin is found 3.3 mm proximal to the articular surface and 3.5 mm from the dorsal surface of the metacarpal. The RCL insertion is 2.5 mm distal to articular surface and 2.8 mm from the volar cortex of the proximal phalanx. The width of the RCL origin is often greater than its insertion, which is thought to contribute to the higher incidence of avulsions off the metacarpal. In 1 study, 55% of RCL injuries were proximal, 29% distal, and 16% midsubstance, which is notably different from UCL injury patterns. Stener-equivalent lesions are much less frequently seen following RCL injuries because of the broader and more dorsal position of the APB aponeurosis, although they have been described on rare occasions. , Joint subluxation is more commonly seen with RCL injuries, in which the proximal phalanx subluxates in a volar and ulnar direction because of the powerful deforming pull of the adductor pollicis insertion on the proximal phalanx and ulnar sesamoid.


Preoperative evaluation


A thorough evaluation should begin with careful history taking, in which the patient describes the mechanism of injury emphasizing the direction of force applied to the thumb. In addition to skiing, other common mechanisms to consider in athletes include forceful radial or ulnar deviation of the thumb from collision with other players, or from contact with balls or other equipment. In baseball, for example, a common mechanism of UCL injury includes sliding into a base head first with an outstretched and abducted thumb.


Acute injuries are commonly accompanied by ecchymosis, swelling, and point tenderness along the radial or ulnar side of the MCP joint. It is also important to attempt to identify the point of maximal tenderness, remembering that UCL injuries typically occur distally at its insertion site and RCL injuries commonly occur proximally at the metacarpal origin. In more chronic conditions, players may complain of weakness with gripping equipment or difficulty with throwing or grasping. The examiner should palpate for the presence of a Stener lesion, which would indicate a complete tear of the UCL with retraction superficial to the adductor aponeurosis. However, absence of a palpable Stener lesion does not definitively rule out its presence. ,


AP and lateral radiographs should be obtained evaluating for bony avulsions, fractures, presence of osteoarthritis, or subluxation of the MCP joint. Stability of the MCP joint should then be assessed by testing the integrity of the collateral ligaments and comparing them with the uninjured thumb. Stress examination should be performed in full extension to evaluate the accessory collateral ligament and volar plate, and at 30° of flexion to test the proper collateral ligament. The metacarpal head should be stabilized with the opposite hand, and the examiner must be careful to avoid MCP joint rotation, which may falsely mimic lateral instability, especially in patients with round metacarpal head morphology. In the setting of suspected RCL injury, the thumb may lie in an ulnarly deviated position from the pull of the adductor pollicis and should be corrected to a neutral position before testing. If the patient is showing significant guarding that interferes with the ligamentous examination, local anesthetic may be a useful adjunct. Degrees of laxity as well as the presence or absence of a firm end point should be noted. In suspected RCL injuries, anterior and posterior drawer testing should be performed as well. A study of 100 asymptomatic thumbs found that it was common to have greater than 10° of variability between sides when testing lateral stability.


Grading of both UCL and RCL injuries follows the same 3 stage classification. Grade 1 denotes pain along the collateral ligament without laxity to stress. Grade 2 injuries represent partial tears with asymmetric laxity and a firm end point. In addition, grade 3 injuries are complete tears with increased laxity and no discernible end point. Values to consider when evaluating laxity in complete tears is greater than 30° of coronal plane deviation and greater than 15° relative to the uninjured side. As discussed later, differentiating between partial and complete tears is critical to guiding treatment.


Debate exists regarding the role of stress radiographs in evaluating collateral ligament injuries, with opponents concerned that it may displace or complete a partial injury. A cadaveric study showed that stress radiographs can differentiate between partial and complete UCL tears, in which more than 2 mm of radial translation of the proximal phalanx is only possible with a complete tear. Another important consideration is that fractures at the base of the proximal phalanx may occur separate from, or in combination with, tears of the collateral ligaments. In this setting, clinical examination to assess coronal stability should be used in combination with radiographic findings for accurate diagnosis. Fracture of the proximal phalanx is not a contraindication to stress testing of the MCP joint. MCP joint subluxation on a lateral radiograph is more commonly seen with RCL injuries, in which palmar subluxation greater than 3 mm is often a sign of a complete RCL tear with a dorsal capsular disruption.


MRI may be useful in the setting of an equivocal clinical diagnosis to evaluate for collateral ligament injury or to identify the presence of a Stener lesion; however, MRI is not required to make the diagnosis in the setting of a clear history and physical examination ( Fig. 2 ). The sensitivity and specificity of MRI for UCL injuries has been found to be as high as 100%, and it is the most reliable imaging modality to establish the diagnosis. , Ultrasonography has been used and studied as a diagnostic modality for diagnosing collateral ligament injuries. It is less expensive and often quicker than MRI, with a sensitivity between 76% and 88% and a specificity between 81% and 83%. ,




Fig. 2


MRI identifying a Stener lesion ( arrows ).


Treatment considerations


Treatment considerations need to take into account the level of athletic participation, hand dominance, demands on the thumb during the athlete’s respective sport, the physical ability to play with a splint/cast, the amount of time left in the season, and the patient’s/athlete’s specific goals.




  • Nonoperative treatment:




    • Grade I or II injuries: initial thumb spica immobilization for a minimum of 4 weeks is the gold standard. , ,




  • Operative treatment:




    • Grade III UCL tear with Stener lesion.



    • Grade III RCL: rationale for surgical treatment is based on the unopposed ulnar deviation at proximal phalanx from the adductor pollicis and extensor pollicis longus (EPL), which may lead to RCL healing in an elongated and displaced position. Repair may allow it to heal in a more anatomic position. ,



    • Articular fracture involving greater than 30% of the articular surface or articular incongruity.




  • Controversy surrounds the treatment of:




    • Grade III UCL injuries without Stener lesion or joint subluxation: there is potential for healing without surgery if the ligament disruption is nondisplaced. Landsman and colleagues showed successful nonoperative immobilization for 34 out of 40 acute complete UCL ruptures with or without bony avulsion. Furthermore, final follow-up range of motion was 60% to 100% of the contralateral thumb, 28 of 34 reported no pain, the average pinch strength was 92% compared with the contralateral thumb, and all bony avulsions united radiographically.



    • Avulsion fractures at UCL origin: good results have been shown with nonoperative management if there is no instability with stress despite 25% to 60% radiographic nonunion rates. , Kuz and colleagues identified 30 patients with both displaced and nondisplaced avulsion fractures treated in thumb spica immobilization for 4 weeks. Subjectively, 29 patients reported mild pain (N = 10) or no pain (N = 19) at final follow-up and 23 patients reported their thumb was as strong as before injury. Objectively, 20 were available for clinical examination, with 3 showing instability and 15 with radiographic union, and none were found to have loss of grasp or key pinch strength. In contrast, minimally displaced but malrotated fractures may lead to persistent pain and thus do better with operative fixation.




  • Contraindications to surgery:




    • Chronic tears with associated MCP osteoarthritis.




Surgical technique





  • Acute UCL procedure



    • 1.

      Supine with an arm board and a well-padded tourniquet with general or regional anesthesia.


    • 2.

      A curvilinear skin incision is made over the dorsal ulnar aspect of thumb MCP joint.


    • 3.

      Blunt dissection is performed to identify and protect the dorsal radial sensory nerve branch followed by gentle dorsal retraction of this branch throughout the procedure.


    • 4.

      Identify the EPL and the adductor pollicis aponeurosis.


    • 5.

      Incise the aponeurosis longitudinally approximately 2 to 3 mm volar to its insertion to provide a cuff for later repair.



      • a.

        At this point, a Stener lesion will be apparent with the UCL being superficial and proximal to the aponeurosis.



    • 6.

      Isolate the torn UCL and mobilize:



      • a.

        Subacute or chronic cases: the UCL may adhere to surrounding tissue and require further dissection.



    • 7.

      Identify and roughen the insertion site with a curette.


    • 8.

      Repair the UCL with suture only, suture anchor, or suture tape augmentation:



      • a.

        Place sutures or anchor at the anatomic insertion point paralleling the joint surface.


      • b.

        Avulsion fragments can be excised if small enough. If greater than 20% articular surface, retain and stabilize fragment with Kirschner wires or screw.



    • 9.

      Repair dorsal capsular rent with 3-0 absorbable suture ideally with the MCP joint in flexion.


    • 10.

      Repair adductor pollicis aponeurosis.


    • 11.

      Assess stability of MCP joint in both full extension and 30° flexion.


    • 12.

      Close wound and place patient in thumb spica splint.




Postoperative protocol





  • Acute UCL tears:




    • Thumb spica splint/cast for up to 4 weeks, interphalangeal joint free.



    • At 4 to 6 weeks, removable thumb spica splint, and protected range-of-motion exercises.



    • At 6 to 12 weeks, begin adductor and interossei strengthening, avoiding valgus stress on thumb MCP.



    • At 10 to 12 weeks, return to full activity without brace.




  • Chronic UCL tears:




    • Casting for 6 weeks.



    • At 6 to 8 weeks, removable thumb spica splint, protected range-of-motion exercises.



    • At 8 to 12 weeks, begin adductor and interossei strengthening, avoiding valgus stress on thumb MCP.



    • At 12 to 16 weeks, return to full activity without brace.




Chronic Ulnar Collateral Ligament Considerations


In chronic cases in which the ligament is deemed irreparable, and there is no evidence of arthritis, the ligament remnants are excised to expose the UCL origin and insertion. In this case, an autograft tendon (palmaris longus if present) is used in a triangular configuration with the apex proximal with a distal bone tunnel or it is placed anatomically into the origin and insertion of the proper collateral ligament with interference screws. The MCP joint dorsal capsular rent is repaired with 3-0 absorbable suture, the adductor pollicis aponeurosis reapproximated, then the wound is closed and a thumb spica splint is applied.


Surgical technical considerations





  • Direct primary repair: when feasible, if native tissue is robust and easily identified.




    • Christensen and colleagues performed a retrospective review of patients who underwent primary repair for a chronic UCL injury (>6 weeks). They identified 24 patients who met their inclusion criteria and 12 were available for long-term follow-up. They reported excellent patient-reported outcomes in terms of satisfaction, overall pain relief, function, and stability. In the chronic setting, primary repair may be considered as an alternative to reconstruction.




  • Transosseous suture: historical description in which the repair is tied over a button on the radial side of the thumb.



  • Suture anchors or interference screws: efficient, shorter surgical times, minimal soft tissue complications.




    • A 2014 retrospective review of collegiate football athletes with UCL injuries treated with suture anchor had quicker return to play, reliable return to same level of activity, and excellent long-term outcomes. Skilled players were permitted to return to play in a fabricated orthosis or with taping after an initial 5-week period of immobilization. Non–skill-position athletes were allowed to practice and play in thumb spica cast after the 1-week wound check. All athletes returned to same level of play, without any postoperative complications, and with an average Quick-DASH score of 1 out of 100 (95% confidence interval, 0.4 to 2.3).




  • Suture tape augmentation (Arthrex Internal Brace): emerging technique for UCL repair/augmentation. A recent cadaveric study found the maximum load and load to clinical failure in the UCL repair group with suture tape augmentation to be 5 times and 4 times higher compared with the UCL repair–only specimens, respectively. Caution is needed to avoid overtightening the repair with this technique.


Aug 15, 2020 | Posted by in SPORT MEDICINE | Comments Off on Thumb Metacarpophalangeal Ulnar and Radial Collateral Ligament Injuries
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