Abstract
Five patients with chronic instability of digital joints presented with instability and functional disability. Two patients had ulnar collateral ligament damage of the thumb metacarpophalangeal joint and another had chronic multidirectional instability due to radial collateral ligament, dorsal capsule and palmar plate laxity of the metacarpophalangeal joint of the thumb. The fourth patient had a lax radial collateral ligament and palmar plate of the proximal interphalangeal joint of the little finger and the fifth had chronic laxity of the ulnar collateral ligament of the interphalangeal joint of the thumb. All were reconstructed with bone–ligament–bone graft harvested from the iliac crest. The graft was fixed with screws and joint stability was achieved intra-operatively in all patients. All patients achieved a stable joint with improved functional performance at final followup.
INTRODUCTION
Non-rheumatoid chronic instability of digital joints is most commonly encountered at the metacarpophalangeal joint of the thumb and the proximal interphalangeal joint of fingers. It can cause significant functional disability and often requires surgical treatment. We report a new method using bone–ligament–bone (BLB) graft harvested from the iliac crest with the overlying tendinous fibres to restore joint stability.
PATIENTS AND METHODS
Five patients with chronic instability of joints of the thumb or fingers were treated between 1998 and 2001. There were two men and three women with a mean age of 41 (range, 22–59) years. Three patients had thumb metacarpophalangeal joint involvement, one had instability of the proximal interphalangeal joint of the little finger and the last had instability of the thumb interphalangeal joint. Details of each patient are summarized in Table 1.
Surgical technique
The affected joint is explored from the radial or ulnar side, depending on which collateral ligament is lax. Bone troughs are prepared at the sites of origin and insertion of the damaged collateral ligament. The trough at the origin has to be slightly dorsal to, and the trough at the insertion has to be slightly palmar to, the midlateral line so as to place the graft in the same orientation as the collateral ligament. The bone trough sare usually 5 mm in diameter.
The BLB graft is harvested from the iliac crest, usually on the side of the hand undergoing surgery. The overlying tendinous fibres are thickest over the tubercle of the iliac crest, and thus for large finger joints with thick collateral ligaments, we recommend harvest of the graft from this site. The graft can be harvested from the anterior part of the iliac crest for smaller joints. The bony part of the BLB graft should preferably be harvested from the inner half of the iliac crest where the cortical bone is thinner and less hard. For joints with concomitant dorsal or palmar instability, a wider segment of the tendinous fibres over the iliac crest should be harvested. This will facilitate attachment of the graft to the dorsal joint capsule and the palmar plate, reduce joint volume and restore joint stability in other directions. The length of the BLB graft should be the same as the distance between the two bony troughs in the digit.
Once the graft is harvested, the size of the two bone pegs at either end is determined (Fig 1) and the bone at the centre is remove d to create the bone–ligament–bone graft. The space between the two bone pegs should be prepared carefully so that the length of the ligament is equal to the shortest distance between the edges of the two bone troughs across the joint. The use of a high-speed burr greatly facilitates the preparation of this graft and a 1.0 mm diameter burr is very useful for shaping the bases of the bone pegs. A drill hole is made at the centre of each bone peg to facilitate the subsequent insertion of screws.
The prepared BLB is placed across the joint and its bone pegs are inserted into the prepared troughs. The appropriate drill bit is then passed through the previously prepared tract in the bone peg and drilled through the opposite cortex. After tapping, screws with washers are inserted to avoid fracturing of the bone pegs. Either 2.0 or 1.5 mm diameter screws are used, depending on the size of the bone. If there is significant dorsal or palmar instability, the ligamentous part of the BLB graft is sutured to the dorsal capsule or the palmar plate. Stability of the joint is thus restored immediately and the position of the screws is checked with intra-operative radiographs. For the metacarpophalangeal joint of the thumb, the adductor or abductor pollucis tendon can be sutured to the ligamentous part of the graft to act as dynamic stabilizers.
A boxing glove dressing is worn for 1 or 2 days and gentle mobilization exercises are started early. No plaster immobilization is required. Strengthening exercises are usually started about 1 month after the operation.
CASE REPORTS
Patient 1 (Fig 2)
A 59-year-old man ruptured the ulnar collateral ligament (UCL) of his left thumb and developed ulnar instability of its metacarpophalangeal joint. He did not agree to undergo operative treatment until 6 months after the initial injury. At surgery, the ulnar collateral ligament of the metacarpophalangeal joint was found avulsed from its attachment at the base of the proximal phalanx. It had contracted and could not be reattached to the proximal phalanx. A BLB graft was prepared and inserted using the above technique and immediately restored stability. The adductor pollicis tendon was sutured to the ligamentous part of the graft as a dynamic stabilizer. The BLB graft healed well and the metacarpophalangeal joint remained stable and pain free. The range of motion was the same as for the contralateral thumb.
Patient 3 (Fig 3)
A 33-year-old lady injured the left thumb and was initially treated with a splint. She was later referred to us with pain on the radial side of its metacarpophalangeal joint. Physical examination revealed that the radial collateral ligament was very lax and there was also marked dorsal and palmar translation laxity. A diagnosis of multi-directional instability was made and was treated 8 months after the injury with a BLB graft. The graft replaced the radial collateral ligament and its dorsal and palmar edges were sutured to the dorsal joint capsule and the palmar plate so as to reduce the joint volume and restore stability in all directions. The joint became stable immediately after fixation of the graft. The tendon of the abductor pollicis brevis was also sutured to the graft to act as a dynamic stabilizer and the metacarpophalangeal joint was immobilized with a K-wire for 2 weeks. Five years after the operation, the bone graft has healed and the joint is stable with 80% of the range of motion of the normal side.
Patient 4 (Fig 4)
A 26-year-old man sustained a left little finger proximal interphalangeal joint injury and attended our clinic 8 months afterwards. There was gross laxity of the radial collateral ligament and the palmar plate which was treated with BLB graft. At final follow-up, the graft had healed and the joint was stable.
Patient 5 (Fig 5)
A 55-year-old lady complained of gradual onset instability and discomfort on the ulnar side of the interphalangeal joint of the right thumb. She had worked for the same factory for 20 years and her job required repeated pressing of her thumb against metal plates. There was chronic ulnar collateral ligament laxity of the joint which, after surgical treatment with BLB graft, became stable with a full range of motion.
RESULTS
The mean duration of follow up was3 (range, 1–5) years. All patients achieved a pain-free joint with excellent stability after surgery. There was no subsequent stretching out of the reconstructed ligament. The range of motion, power grip and pinch grip were the same, or almost the same, as on the contralateral digit in four of the five cases (Table 1). All patients returned to their original employment and sporting activities. Case 5 was advised to use a splint to protect the interphalangeal joint of the thumb during work.
DISCUSSION
Reconstruction of chronic instability of digital joints is very challenging, and it is now recognized that the instability may not be just in one direction (Breek et al., 1989). If an ulnar collateral ligament tear of the metacarpophalangeal joint extends to involve the dorsal joint capsule, palmar subluxation as well as ulnar instability of the joint may occur (Glickel, 2002). Radial instability of the metacarpophalangeal joint of the thumb secondary to injury to the radial collateral ligament injury is also increasingly recognized and represents 10% to 40% of the collateral ligament injuries to this joint (Camp et al., 1980; Coyle, 2003; Durham et al., 1993; Loebig et al., 1995; Melone et al., 2000). Concomitant injuries to the dorsal joint capsule and the palmar plate may give rise to multi-directional instability as in Case 3 (Coyle, 2003; Posner and Retaillaud, 1992).
Chronic collateral ligament instability and hyperextension of the proximal interaphalangeal joints of the fingersis uncommon and there are only a few reports of its surgical treatment (Ahmed and Goldie, 2002; Lane, 1978; Liss and Green, 1992; Palmer and Linscheid, 1978). Instabilities of the finger joints in more than one direction are conceptually similar to injuries to the shoulder joint, though much less common. A detailed physical examination before the surgery is important, and assessment of joint instability in different directions will indicate which ligament or structure may be torn or have become lax.
Operations to treat these chronic instabilities can be grouped into static and dynamic procedures. Static procedures mostly use a tendon graft to replace the damaged ligament. In dynamic procedures, a musculotendinous unit is used to pull the bone distal to the joint in the opposite direction to the instability. Muscletendon units that had been used for the dynamic stabilization of ulnar collateral instability of the metacarpophalangeal joint of the thumb include the extensor indicis proprius (Kaplan, 1961), the adductor pollicis (Neviaser et al., 1971) and the extensor pollicis brevis (Sakellarides and DeWeese, 1976).
When a tendon graft is used to replace the damaged collateral ligament, various configurations, including a figure-of-eight, rectangular and triangular, can be used (Breek et al., 1989; Glickel et al., 1993; Melone et al., 2000). Glickel (2002) emphasized that the graft should duplicate the normal anatomy of the ulnar collateral ligament. Its origin is narrow and discrete and insertion extends from dorsal to palmar on the ulnar surface of the proximal phalanx. The triangular configuration resists radial deviation of the proximal phalanx and its tendency to palmar subluxation. Joint stiffness is one possible complication as a result of postoperative immobilization and excessive tightness of the graft (Breek et al., 1989; Glickel, 2002). When inserting those grafts, drill holes have to be made in the bones, and the bony bridges between the holes may fracture during the procedure. When stabilizing the proximal interphalangeal joint, the drill holes cannot be very large as the adjacent phalanges are small and only a thin tendon graft can pass through the holes.
Few papers address the surgical treatment of combined collateral ligament and palmar plate laxity of the proximal interphalangeal joints of the fingers. Methods of repair include a dynamic tenodesis using the intact superficialis tendon and a palmaris longus tendon graft (Lane, 1978). Lane (1978) described the use of the two distally based slips of the flexor digitorum superficialis: one to reconstruct the collateral ligament and the other to replace the palmar plate and prevent hyperextension. Palmer and Linscheid (1978) described the use of one slip of the distally based superficialis tendon to reconstruct the collateral ligament and the palmar plate simultaneously. However both methods require the sacrifice of one flexor tendon, and thus cannot be used in the thumb. Ahmed and Goldie (2002) reported the use of a strip of the lateral band of the extensor tendon to treat combined laxity of the collateral ligament and the palmar plate. The extensor tendon slip was based distally and was divided proximal to the proximal interphalangeal joint. A drill hole was then made in the head of proximal phalanx and the lateral band was routed palmar to the Cleland’s ligament, through the drill hole and sutured or tied at the other side. In this method, the tenodesis effect acted as a checkrein to prevent proximal interphalangeal joint hyperextension. The disadvantages of this method are that it requires sacrifice of part of the extensor complex and that it does not address the distal insertion of the collateral ligament.
Non-rheumatoid chronic instability of the interphalangeal joint of the thumb is even more uncommon. In rheumatoid patients, it is usually treated by arthrodesis of the joint and the results are good.
There are many advantages to the use of the BLB graft which we describe. The finger tendons are not disturbed and the donor site morbidity is minimal. The tendinous tissue over the iliac crest is thick and sufficient to replace the collateral ligaments of finger joints. The bone pegs of the graft unite with the phalangeal bones which is better than the tendon to bone healing of traditional methods. The graft itself has good stability once in place and the fixation is further augmented by screws, such that the joint can be mobilized early.
Histological studies of the tendinous fibres over the iliac crest show that the fibres lie in criss-cross arrangement (Fig 6). They take sutures well and, unlike tendon grafts, do not split. This is a very useful feature when it is necessary to suture the graft to dorsal or palmar capsular structures to reduce joint volume and enhance stability of the joint.
Footnotes
Acknowledgements
We would like to thank Dr Florence Cheung of the Clinical Pathology Department in the histological study of the tendinous fibres over the iliac crest.