Author:  Alejandro Badia, M.D, F.A.C.S. ; Felix Riano, MD

Arthroscopy is an effective, minimally invasive method to reduce and fix avulsed and rotated fragments from the ulnar collateral ligament of the metacarpophalangeal joint.
Lesion of the ulnar collateral ligament of the thumb is common in athletes.1 It usually is due to forced radial deviation of the metacarpophalangeal joint causing damage to the structures that provide stability to the ulnar side.2 These injuries may present as avulsion fractures or as tears within the substance of the ligament, or at its insertion point on the proximal phalanx. The most common pattern is an avulsion fracture at the insertion point of the base of the proximal phalanx.3 Stener4 described a model of injury characterized by the interposition of the aponeurosis of the thumb adductor between the distally avulsed ulnar collateral ligament and its insertion into the base of the proximal phalanx. The Stener lesion is an operative indication for the anatomic reasons described, as is a displaced bony avulsion connected to the collateral ligament.
Several nonoperative and surgical solutions have been proposed for this problem.5-13 Metacarpophalangeal arthroscopic literature is limited and is commonly related to synovectomy for diseases such as rheumatoid arthritis and hemachromatosis.14-18 One report focuses on the treatment of thumb metacarpophalangeal ulnar collateral ligament tears.10 The clinical usefulness of arthroscopy is best suited for avulsion fractures since the minimally invasive technique allows for derotation of the fragment and a more anatomic reduction. This article reports an experience with arthroscopic treatment of bony gamekeeper’s thumb.

Materials and Methods
Twelve patients (9 male and 3 female) with unstable bony gamekeeper’s lesion were treated arthroscopically. Average patient age was 18 years (range: 16-21 years). All patients were right-hand dominant college students. The left thumb was involved in 5 patients and the right in 7 patients. The mechanism of injury in all cases was hyperabduction of the metacarpophalangeal joint of the thumb while practicing sports. The avulsed fragment was at the insertion point of the ulnar collateral ligament on the base of the proximal phalanx in all patients. Average fragment rotation was 46° (range: 40°-60°). Fragment displacement averaged 2.5 mm (range: 2-4 mm). Surgical indications consisted of significant fragment rotation or displacement >2 mm. All patients underwent arthroscopic-assisted reduction of the avulsed fragment combined with percutaneous pinning with a single 0.035-inch Kirschner wire followed by immobilization with a short-arm thumb spica cast. Average follow-up was 34.2 months (range: 12-84 months).

Surgical Technique
The patient’s hand is sterilely prepped once regional wrist block anesthesia and light intravenous sedation is achieved. Traction is achieved via a finger trap placed on the thumb with 5 lbs suspended from a shoulder holder pulley system. A traction tower is not used as this may prove cumbersome when fluoroscopy is later introduced to the operative field. One to two cubic centimeters of lidocaine is introduced into the joint using an 18-gauge needle, careful not to injure the articular cartilage of the metacarpal head. A marking pen can be used to indicate the palpable base of the proximal phalanx. A 1.9-mm 30° arthroscope is inserted via a longitudinal portal stab wound. This portal should be placed radial to the extensor tendon since the pathology is on the ulnar side (Figure 1). A 2.0-mm full radius shaver initially is used to remove any hematoma or minute fragments that may initially be encountered as sequelae to the fracture.

An aggressive synovectomy is then performed with emphasis on the ulnar side to more clearly delineate the avulsed fracture fragment. Preoperative radiographs help indicate what fracture reduction maneuver will be necessary (Figure 2); however, the arthroscopic finding will ultimately determine the direction of fragment derotation required to achieve reduction and cancellous bony apposition. Usually, the probe is inserted through the ulnar portal and the fragment is hooked on its radial side within the fracture site with a gentle proximal-radial traction leading to reduction. The shaver can be inserted into the fracture site for debridement and also will assist in achieving adequate reduction without step-off or even diastasis (Figures 3 and 4). A 0.035 K-wire then is manually introduced into the joint just proximal to the bony fragment that has been reduced. The arthroscopic view will allow the tip to be placed on the fragment with the substance of the attached collateral ligament and also determine the direction of pinning (Figure 5A). Once in place and manually held, the fluoroscope is brought in to help guide the pin as the K-wire driver is used to engage the pin on the radial cortex of the proximal phalanx distally (Figure 5B). Both fluoroscopy and arthroscopy are used to determine quality of fragment reduction as well as to confirm proper wire placement and stability (Figure 6). The wire is cut just underneath the skin and a bulky thumb spica plaster splint is applied with the thumb still suspended. Final fluoroscopic pictures are taken and the tourniquet is released.

A fiberglass thumb spica short arm cast is applied at one week postoperatively, and the pin is removed with local anesthesia at approximately 5 weeks postoperatively (Figure 7). A brief course of therapy is initiated with a hand-based thumb carpometacarpal-type removable splint provided to the patient for use in strenuous activities. Therapy usually is minimal, as there is minimal metacarpophalangeal capsular swelling or stiffness as seen with open approaches. All unrestricted activities are permitted at 8 weeks (Figure 8).

Average tourniquet time was 15 min (range: 10-25 min). Average lateral pinch strength at final follow-up was 16 lbs (range: 14-18 lbs), and it was 98% from the unaffected side. The avulsed fragment healed in an average 4.3 weeks (range: 4-5 weeks). Fragment healing was defined as the absence of fracture lines on radiographic studies and lack of pain on physical examination. At final follow-up, the compromised metacarpophalangeal joint was stable to stress maneuvers performed at extension and 30° of flexion. The final metacarpophalangeal and interphalangeal range of motion were on average 0°-60° (range: 0°-65°) and 0°-88° (range: 0°-90°) respectively. No patient reported pain at final follow-up. All patients returned to their previous activities within 3 months.

Small-joint arthroscopy has become commonplace in the surgeon’s armamentarium; however, use of this method in the metacarpophalangeal joints has mainly been focused on treating inflammatory conditions by performing synovectomy.14-18 Treatment of a soft-tissue ulnar collateral ligament tear also has been managed arthroscopically. Ryu and Fagan10 reported on 8 patients with Stener lesions in the thumb treated arthroscopically. According to the surgical description, retrieval of the distal end of the ligament was achieved by introducing a probe between the inner wall of the thumb adductor and the metacarpal head. They then placed it at its insertion point at the base of the proximal phalanx without securing it. The metacarpophalangeal joint was held in 20°-30° of flexion by crossing it with a single 0.045-inch K-wire. They followed the patients for an average of 39 months and obtained the following results: pinch strength of 19 lbs, no appreciable metacarpophalangeal laxity, interphalangeal motion of 102°, and metacarpophalangeal motion of 51°.

Arthroscopy was used to treat 12 patients in the current study with unstable bony gamekeeper’s lesion. This technique differed from Ryu and Fagan’s10 in that fixation of the avulsed fragment was performed with a 0.035-inch K-wire and it was not necessary to cross the metacarpophalangeal joint. Fracture healing in the current study occurred faster (4.3 weeks). The final average pinch strength was 16 lbs, corresponding to 98% of the opposite thumb. Range of motion for the metacarpophalangeal and interphalangeal joints was 0°-60° and 0°-88° respectively. At final follow-up, complete metacarpophalangeal joint stability was achieved to stress maneuvers in extension and 30° of flexion.

There are various advantages to arthroscopic-assisted reduction and percutaneous fixation of the avulsed fragment when compared to open reduction. First, by using this technique there is no need to violate the joint capsule to achieve reduction, hence it is feasible to shorten the rehabilitation period. Total surgical and tourniquet time are shorter compared to open reduction. Less scarring is involved, including a better cosmetic appearance without sacrificing function or stability as the main goals of the surgical procedure. Finally, thorough assessment of the entire joint surface prevents any residual articular step-off. Irrigation of the joint allows for a decreased postoperative inflammatory response while allowing removal of any small osteochondral fragments that might remain inside the joint acting as a persistent irritant. One can also address chondral lesions encountered and perform shrinkage capsulorraphy if the attached ligaments are attenuated or partially torn. Excessive abduction or extension forces applied to the metacarpophalangeal joint of the thumb usually result in either rupture or avulsion of the ulnar collateral ligament.2 Immobilization of the metacarpophalangeal joint has generally been accepted to treat acute partial ulnar collateral ligament ruptures;10 however, management of complete rupture of this ligament is controversial.19-23 On the other hand, avulsed and rotated fragments with significant displacement demand open reduction and internal fixation to restore stability as well as articular reduction of the fragment.

Several internal fixation techniques have been suggested for avulsion fractures at the metacarpophalangeal joint.1,4,11,13,23 Kozin and Bishop11 reported treating avulsion fractures of the thumb ulnar collateral ligament in 7 patients and the radial collateral ligament in 2 patients with open reduction and tension-wire fixation. All injuries were treated within two weeks from original trauma. The avulsion occurred from the volar aspect of the proximal phalanx in every case. Average fragment rotation was 47°. In their study, to obtain satisfactory fragment reduction it was necessary to incise both the adductor aponeurosis and the joint capsule to achieve proper visualization of the articular surface. Average fracture healing time was 6 weeks. At final follow-up (26 months) all the thumbs displayed good stability in extension and 30° of flexion. The metacarpophalangeal and interphalangeal motion averaged 77% and 97% of contralateral side respectively. Pinch strength averaged 97% from opposite thumb.
Gamekeeper’s thumbs with a bony fragment are better managed with an arthroscopic reduction. The advantages of arthroscopic versus open techniques are similar to those experienced in larger joints, and this technique is recommended for the treatment of displaced bony gamekeeper’s lesions that require reduction.

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