Arthroscopic and Open Primary Repair of Acute Thumb Metacarpophalangeal Joint Radial and Ulnar Collateral Ligament Disruptions

 

 

 

DEFINITION

Ulnar collateral ligament (UCL) and radial collateral ligament (RCL) tears of the thumb metacarpophalangeal joint (MCP) are common injuries resulting from disruption of the continuity of these ligaments.

These disruptions are frequently the result of an athletic injury, a fall, or a motor vehicle accident.

 

 

ANATOMY

 

The MCP joint of the thumb is transitional between a condyloid and ginglymus joint. The articulating surface of the base of the proximal phalanx is a shallow concavity that provides relatively little intrinsic stability. Hence, most of the joint's stability is afforded by its ligament and capsular supports.

 

The RCL and UCL are both structurally similar, composed of both proper and accessory components, and are the main stabilizers of the thumb MCP joint.27

 

The proper collateral ligaments, which originate from a fossa in the metacarpal neck dorsal to the axis of rotation, are the primary ligamentous supports. They fan out from their proximal origins to distal insertions on the lateral and volar aspects of the base of proximal phalanx.

 

 

The accessory collateral ligaments act as supplementary supports originating from the palmar aspect of the metacarpal neck fossa and inserting into the volar plate and the sesamoid on respective sides of the joint.27 The collateral ligaments provide not only medial and lateral stability but also stability in the dorsovolar plane by

virtue of their dorsal origin and their volar insertion.26

 

The volar plate is a central fibrocartilaginous structure extending from the neck of the metacarpal proximally to the base of the proximal phalanx distally.

 

One difference between the ulnar and radial sides of the MCP joint is related to the aponeurosis. The broad abductor aponeurosis covers the entire radial side of the MCP joint, whereas the much narrower adductor aponeurotic sheath spans the ulnar side of the joint.

 

PATHOGENESIS

 

Acute injury of the UCL usually results from sudden forceful abduction and extension at the thumb MCP joint.21,25

 

This can take place during a fall on an outstretched hand with the thumb abducted, as seen in skiers,8 or in baseball players when the glove strikes the ground while fielding.

 

The extent of the injury and the grade of the injury depend on the loading force at the time of impact. The

most common injury of the thumb MCP joint is a partial disruption or sprain of the UCL.

 

Tears of the UCL can occur anywhere within the ligament's substance, although most take place at or near the site of insertion into the proximal phalanx, sometimes with an avulsion fracture (FIG 1A).4,9,28

 

The narrower adductor sheath on the ulnar aspect of the joint allows superficial displacement and entrapment of the torn proximal end of UCL, termed a Stener lesion (FIG 1B).28 Because of the broader abductor aponeurosis, however, such a lesion is not seen on the radial side.11

 

RCL injuries are generally caused by sudden adduction and extension of the MCP joint, commonly occurring during athletic injuries.5 They can also occur by direct blunt impact to the lateral side of the thumb.

 

The RCL is more often injured close to its origin on the dorsoradial metacarpal head. It may also be disrupted in its midsubstance.

 

NATURAL HISTORY

 

Untreated UCL injuries are relatively common. Patients are often sent away being told they simply have a “sprain.” If instability is present and not corrected, the patient may experience pinch weakness and eventually chronic pain.

 

Untreated RCL tears are even more common and often result in late degenerative arthritis, commonly requiring MCP arthrodesis.

 

 

Less severe avulsions may lead to prominent osteophytes on the dorsoradial aspect of the metacarpal neck, suggesting the prior injury.

 

 

Mondry19 first described the unstable thumb MCP joint in 1940, whereas Watson-Jones30 mentioned the importance of the UCL in relation to stability of the MCP joint of the thumb.

 

 

 

Campbell6 described gamekeeper's thumb as a chronic instability of the UCL in Scottish gamekeepers. Gerber et al13 popularized the term skier's thumb to refer to acute UCL injuries.

 

Stener28 outlined the ligamentous anatomy of the thumb MCP joint and subsequent pathoanatomy of the lesion now termed the Stener lesion. Stener also described

 

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avulsion of the UCL leading to articular fracture of the proximal phalanx, now popularly referred to as a bony gamekeeper's thumb.29

 

 

 

FIG 1 • A. A bony gamekeeper's thumb. B. The narrow adductor aponeurosis is interposed between the avulsed ligament-bone and the site of attachment.

 

 

Moberg and Stener18 reported that UCL disruption is 10 times more common than RCL disruption. This frequency has been widely confirmed.9,23,26

 

Frank and Dobyns12 reported that RCL injuries are somewhat more common than initially thought, with incidences ranging from 23% to 35% of collateral ligament injuries.

 

 

This has echoed our experiences with the more subtle RCL injuries often being neglected, causing late morbidity.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

Ulnar Collateral Ligament Tears

 

Patients with UCL tears present with pain, stiffness, tenderness, and swelling of the MCP joint. The defining symptom, however, may be marked pinch weakness.

 

On examination, there is discrete tenderness over the ulnar joint line, at the ulnar side of the metacarpal neck, and most classically at the volar ulnar base of the proximal phalanx.2

 

Physical examination is critical in establishing the need for surgical treatment by distinguishing between a partial and a complete ligament tear.

 

A valgus stress examination comparing the stability of the injured versus the uninjured UCL is the best method to detect a complete tear.

 

 

The stress test may be aided by live fluoroscopy and the use of a local anesthetic block.

 

The presence of an associated fracture should not deter the examiner from performing a stress test. Nondisplaced avulsion fractures at the insertion site of the proper collateral ligament may coexist with a complete ligament tear.

 

 

The results of the stress test are based on angular instability of the joint and the quality of the “end point.” Laxity of more than 30 degrees in extension and 15 degrees in flexion as compared to the contralateral side should be highly suggestive of a complete tear of the UCL.15

 

The presence of fullness or a palpable mass on the ulnar aspect of the metacarpal head and neck, representing a Stener lesion,1 is strongly suggestive of a completely disrupted and retracted UCL.

 

Volar subluxation of the MCP joint signifies loss of the dorsal volar stabilizing effect of the collateral ligament and is also consistent with a complete tear.

 

Radial Collateral Ligament Tears

 

RCL tears present as localized tenderness over the radial base of the proximal phalanx but more commonly over the metacarpal head.

 

 

The dorsoradial aspect of the metacarpal head may be prominent due to soft tissue swelling. Acute RCL injuries are assessed in the same manner as discussed for UCL injuries.

 

For the stress test of the RCL in extension and 30 degrees of flexion, laxity of the joint greater than 30 degrees as compared to the uninjured side suggests a complete tear of the RCL.

 

The emphasis on distinguishing partial tears from complete tears does not directly affect treatment and therefore is less important than for UCL injuries. Even complete RCL tears are not capable of retracting behind the aponeurosis and therefore may be treated nonoperatively.

 

RCL injuries are more common than often thought. Significant radial-sided pain with laxity or subtle radiographic signs of dorsal capsule avulsion necessitate treatment (FIG 2).

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Radiographs include posteroanterior, lateral, and oblique views of the thumb. Images of the contralateral thumb are used for comparison and may reveal subtle joint subluxation.

 

 

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FIG 2 • Radiograph showing a chronic neglected RCL tear. There is subtle volar subluxation of the proximal phalanx. Oblique views often demonstrate a small bony prominence on the metacarpal neck dorsum.

 

 

Stress radiographs of the MCP joint in full extension and in 30 degrees of flexion are rarely required, although occasionally can help distinguish between a partial and complete ligament injury.4,12

 

MCP joint arthrography, magnetic resonance imaging (MRI), and ultrasound have all been used to determine the degree of ligament injury and displacement but are almost never required.

 

On MRI, a Stener lesion is characterized by a “yo-yo on a string” sign.

DIFFERENTIAL DIAGNOSIS

Diffuse capsular injury without discrete ligament tear Fracture or articular cartilage injury

The articular surface is best assessed via arthroscopy or perhaps MRI. Arthritis

Diffuse soft tissue injury involving a previously asymptomatic but arthritic joint can result in persistent pain.

 

 

FIG 3 • A. Preoperative radiograph showing an avulsion fracture at the UCL insertion site. B. Arthroscopic reduction failed and an open procedure was performed because of the interposition of the adductor aponeurosis at the fracture site and unrecognized fracture comminution. C. Postoperative radiograph showing fixation of the fragment and attachment of the ligament using a Kirschner wire and a bone anchor.

 

 

 

NONOPERATIVE MANAGEMENT

 

Treatment depends on the severity of injury, the type of tear,7,14,16,17,20,22 and the presence of an avulsion fracture involving a significant portion of the articular surface or an open physis.

 

Partial UCL and partial and complete RCL tears without volar subluxation of the proximal phalanx can be effectively managed by immobilization, then protected mobilization using a removable splint for a total of 4 to 6 weeks.

 

 

Initial immobilization is traditionally accomplished using a thumb spica cast. Such a cast allowing wrist motion is preferable.

 

Alternatively, a customized thermoplastic splint that immobilizes only the thumb MCP joint and leaves the wrist and interphalangeal joint free can be used for reliable patients with less severe injuries.

 

SURGICAL MANAGEMENT

 

Complete UCL disruption, especially if denoted by a Stener lesion or joint subluxation, should be treated surgically. Additionally, a displaced avulsion fracture involving a significant portion of the articular surface should be reduced and stabilized operatively.

 

An avulsion fracture of the proximal phalanx can be effectively managed by arthroscopic techniques.3,23,24 Occasionally, it is necessary for an arthroscopic procedure to be converted to an open procedure if reduction of a large or comminuted fracture fragment in the proximal phalanx is not feasible (FIG 3).

 

Injuries associated with a Stener lesion warrant open repair.

 

Partial tears of RCL are best managed by cast immobilization, whereas complete tears associated with palmar subluxation require open surgical repair of the ligament and dorsal capsule.10

 

Arthroscopy can also be a useful adjunct to open procedures, as it allows a more thorough débridement and evaluation of concomitant pathology.

 

A regional anesthetic combined with light intravenous sedation is generally adequate for the procedures detailed

in the following text.

 

 

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TECHNIQUES

• Acute Ulnar Collateral Ligament Disruptions

  Arthroscopic Treatment of Ulnar Collateral Ligament Avulsion Fractures

  Traction is applied using a finger trap placed on the thumb with 5 pounds of counterforce.

  A traction tower is not used in order to facilitate fluoroscopy.

  Palpate the joint and then inject 1 to 2 mL of lidocaine using an 18-gauge needle.

  Take care to avoid injuring the articular cartilage.

  Insert a 1.9-mm 30-degree arthroscope via a longitudinal portal stab wound on the radial side of the extensor pollicis longus tendon.

  This allows the best visualization of the ulnar-sided pathology.

  Insert a 2-mm full-radius shaver in the ulnar portal and evacuate the hematoma and any minute bone fragments that may prevent visualization.

  Perform a synovectomy, with emphasis on the ulnar side. This allows clear delineation of the avulsed fracture fragment (TECH FIG 1A).

  Insert a small probe through the ulnar portal and hook the fragment on its radial side, within the fracture site. Gentle proximal and radial traction on the ulnar fragment typically accomplishes the reduction.

  Preoperative radiographs help to plan the specific maneuver necessary for fracture reduction, but the arthroscopic picture will ultimately determine the direction of fragment derotation required to achieve anatomic reduction of the joint.

   

   

  TECH FIG 1 • A. With the arthroscope in the dorsoradial portal and the shaver in the dorsoulnar portal, arthroscopic débridement is performed before reduction of the fragment. B. The fragment is reduced arthroscopically and stabilized with a Kirschner wire. C. Arthroscopic view showing the Kirschner wire

   

   

  and the fracture fragment before reduction. D. This displaced and rotated bony avulsion fracture at the attachment of the UCL is reduced arthroscopically and stabilized. E. Radiograph showing anatomic arthroscopic reduction and pinning. F. The Kirschner wire, fixing the avulsed fragment, is cut beneath the skin.

   

   

  Reintroduce the shaver as needed for débridement and to assist fracture reduction.

   

  Insert a 0.035-inch Kirschner wire percutaneously into the joint just proximal and ulnar to the reduced bony fragment (TECH FIG 1B).

   

  Arthroscopic visualization aids in placement and orientation of the transfixing Kirschner wire using the wire driver (TECH FIG 1C).

   

  Using the wire driver, engage the radial cortex to stabilize the fracture fragment.

   

  Use both fluoroscopy and arthroscopy to determine the adequacy of fragment reduction as well as to confirm proper wire placement and fracture stability (TECH FIG 1D,E).

   

  Cut the wire just underneath the skin (TECH FIG 1F).

   

   

  Close the skin and apply a bulky thumb spica plaster splint while the thumb is still suspended. Final fluoroscopic pictures are taken and the tourniquet is released.

  Open Repair of Complete Ulnar Collateral Ligament Disruptions

   

  Make a curvilinear or a longitudinal lazy Z incision with the superior or dorsal portion proximal.

   

  The UCL origin is more dorsal and fans out in volar fashion.

   

   

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  Dissect the subcutaneous tissues with small tenotomy scissors, taking care to maintain hemostasis using a bipolar cautery.

   

  Identify the dorsoradial sensory nerve branches and gently retract them dorsally.

   

  Take note of the oblique transverse fibers of the adductor aponeurosis. In more severe injuries, the aponeurosis may be torn, revealing the underlying UCL.

   

  Divide the adductor aponeurosis longitudinally, allowing the muscular origin of the adductor pollicis to pull back the fascia and facilitate posterior retraction of the aponeurosis.

   

  The torn UCL is seen directly under the incised adductor aponeurosis (TECH FIG 2A).

   

  In the case of a Stener lesion, the retracted and displaced stump of the UCL is visualized just superficial to the proximal edge of the adductor aponeurosis before incision.

   

   

  Determine the direction of the UCL fibers and incise the joint capsule on the ligament's dorsal margin. Inspect the joint and perform a limited débridement and synovectomy as indicated.

   

  Precisely determine the location and degree of UCL injury.

   

  Less common intrasubstance tears are repaired primarily with 3-0 or 4-0 permanent suture in a mattress or figure-of-eight configuration.

   

  Avulsion of the ligament attachment from the base of the proximal phalanx is most frequently encountered and is treated by reattaching the ligament's insertion.

   

   

   

  TECH FIG 2 • A. Avulsed UCL (Stener lesion) is well visualized after division of the adductor aponeurosis. B. At the anatomic site of UCL insertion, the bone is prepared and a bone anchor inserted.

   

   

  Isolate the anatomic insertion site for the proper collateral ligament on the volar ulnar base of the proximal phalanx and prepare the site for ligament attachment by débriding the remaining soft tissue down to bleeding bone.

   

  Creating a small bony trough at the insertion site helps stimulate bleeding and ligament attachment (TECH FIG 2B).

   

   

  Prepare the UCL stump by mobilizing it on its margins and freshening the distal end with a no. 15 blade. Insert a 2-mm or smaller suture anchor into the prepared bony site and verify its position with fluoroscopy.

   

  While the thumb is deviated in an ulnar direction, reattach the ligament stump to the proximal phalanx by placing a horizontal mattress stitch using the suture from the anchor.

   

  Repair the accessory portion of the UCL by placing 3-0 or 4-0 permanent suture from the ligament into the ulnar margin of the volar plate.

   

   

  Additional permanent sutures may be placed to secure the repaired UCL to surrounding soft tissues. Close the capsule to the dorsal margin of the ligament using 4-0 absorbable suture.

   

  Precisely reconstruct the adductor aponeurosis with 4-0 inverted interrupted permanent suture and close the skin.

   

   

  Ensure restoration of stability and maintenance of full MCP joint flexion. Place a forearm-based thumb spica splint.

   

  Very severe injuries with extensive disruption of soft tissue stabilizers may rarely require augmentation with a temporary Kirschner wire.

• Acute Radial Collateral Ligament Disruptions

 

Make a dorsoradial curvilinear or a longitudinal lazy Z incision similar to that used for the repair of UCL disruptions and dissect the soft tissues as detailed earlier.

 

Incise the abductor aponeurosis in line with the RCL.

 

Radial-sided lesions are often coupled with concomitant avulsions of the dorsal capsule. If the capsule is intact, incise it along the dorsal margin of the RCL to inspect the joint.

 

Isolate the ligament and its point of disruption, and then mobilize the structure to allow for anatomic repair.

 

Typically, disruptions take place at the proximal origin (TECH FIG 3A).

 

Débride the bone and ligament stump in the manner detailed for open repair of UCL avulsions.

Remove reactive bone and early osteophytes at the site of ligament or capsule avulsion with a rongeur.

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TECH FIG 3 • A. Dorsal capsule to be repaired to the metacarpal head with decortication in a chronic RCL injury. B. Anchors placed in the bone with the ligament ready to be sutured. C. Completed reconstruction of the RCL with repaired abductor aponeurosis and demonstrated course of the radial sensory nerve, which is protected throughout the procedure.

Place a 2.0-mm or smaller suture anchor in the collateral recess, the dorsoradial distal metacarpal.

Ensure proper placement radiographically.

Reattach the ligament to its anatomic point of origin using the suture from the anchor (TECH FIG 3B).

Repair the capsule and further secure the RCL to surrounding soft tissue with 3-0 or 4-0 permanent suture (TECH FIG 3C).

Repair the abductor aponeurosis and skin as described earlier.

Ensure restoration of stability and maintenance of full MCP joint flexion. Place a forearm-based thumb spica splint.

Very severe injuries with extensive disruption of soft tissue stabilizers may rarely require augmentation with a temporary Kirschner wire.

 

 

PEARLS AND PITFALLS

MCP ligamentous lesions require a high index of suspicion.

The obvious lesions with instability will likely get appropriate repairs with subsequent rehabilitation programs.

Missing a significant ligament tear may cause few physical problems short term but may become a chronic painful lesion long term.

This is where arthroscopy may also play a good role. The chronically painful lesions may not demonstrate laxity or even a gross physical problem. Nevertheless, the pain is present and repeat corticosteroid injections are certainly not a solution. Arthroscopic synovectomy or capsular or ligamentous débridement will alter the articular milieu enough to allow for resolution of chronic pain and swelling. All this is coupled with rapid resolution of symptoms and recovery of range of motion.

 

 

 

 

POSTOPERATIVE MANAGEMENT

 

Bony gamekeeper's thumb

 

A fiberglass thumb spica cast is applied at 1 week postoperatively and the pin is removed under local anesthesia at about 5 weeks postoperatively.

 

A brief course of physical therapy is initiated. The patient is given a hand-based thumb-carpometacarpal type of removable splint to be used during strenuous activities.

 

 

Therapy is usually short term, owing to less swelling and stiffness as compared with open approaches. All unrestricted activities are permitted at 8 weeks.

 

UCL and RCL injuries: True ligament-to-bone healing is necessary, so 6 weeks of postoperative thumb spica immobilization is critical to success.

 

 

OUTCOMES

Clinical results after a combined arthroscopic and open procedure can be excellent.

Functional outcome after repair of either UCL or RCL injuries tends to be excellent. Perhaps this is because thumb stability, not MCP motion, is critical to hand function.

Although the MCP joint often remains fairly stiff long after immobilization is discontinued, the resultant disability is minimal, considering that people demonstrate a wide range of normal MCP arc of motion.

Many contralateral thumbs display a flexion arc of less than 20%; therefore, the normal restoration of full motion is not the goal. Good stability without pain should be the aim.

RCL injuries of the thumb tend to have a higher tendency to develop posttraumatic arthritis.

Our long-term experience has shown the need for late arthrodesis on only two occasions. These are cases in which significant volar subluxation is present, and the articular wear at time of surgery was likely predictive of this long-term outcome.

A chronically painful thumb, with any degenerative changes on radiographs, coupled with volar posturing of the phalanx, should likely be considered straightaway for fusion.

Thorough counseling of the patient indicating the minimal deficit produced by arthrodesis is helpful.

 

 

 

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COMPLICATIONS

Careful surgical dissection should avoid the most common complication, which would be iatrogenic trauma to the dorsal sensory nerve. Once done, there are minimal complications associated with this area of hand surgery.

Other complications can include stiffness, as previously discussed, infection, persistent instability, or chronic pain syndromes.

Recalcitrant pain or instability can simply be managed by arthrodesis, still portending a good functional outcome.

 

 

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