Sprains and dislocations of the fingers are common and mainly concern the proximal interphalangeal (PIP) joints of the long fingers, the metacarpophalangeal (MCP) joint of the thumb, and more rarely the MCP joints of the long fingers. These conditions require detailed clinical and radiographic assessment, which should be performed under local anesthesia. These injuries, in the absence of instability, can often be treated conservatively. Unfortunately, splinting is often excessive and wrongly immobilizes the neighboring joints that should be moved. The refinement of tailor-made splints treats most injuries, thereby limiting the risk of the still-too-common major complication—stiffness.
Surgery has well-defined indications, particularly for sprains and dislocations of the thumb, which incur the secondary risk—laxity. Painful instability of the MCP joint of the thumb requires stabilization by ligament reconstruction before osteoarthritis leads to a definitive arthrodesis.
The introduction of absorbable anchors has replaced Bunnel’s pullout technique and its barbwire derivative.
In all cases a clinical examination is essential ; the stability of the joint is assessed, if necessary, under local anesthesia. This examination is both active and passive; in other words, the patient’s ability to reproduce a subluxation or dislocation, as well as passive stability and instability. In the latter case the examiner tests lateral and anteroposterior stability, always comparing with the other side.
Sprains and Dislocations of the Thumb Metacarpophalangeal Joint
Anatomy and Physiology
The MCP joint of the thumb is a condylar joint with 3 degrees of freedom: medial and lateral tilt, axial rotation and flexion-extension, which is the primary movement. It varies from one individual to another.
Function of the thumb requires lateral stability of the joint provided by the ligaments, the joint capsule and the muscles.
Both ulnar and radial collateral ligaments are composed of two parts ( Fig. 5.1 ):
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The proper collateral ligament: strong, powerful, stretched in flexion and relaxed in extension. It is responsible for the lateral stability of the joint in flexion.
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The accessory collateral ligament, itself divided into metacarposesamoid and sesamoid-phalangeal parts, is, on the contrary, stretched in extension and relaxed in flexion. It is responsible for lateral stability in extension.
The medial and lateral thenar muscles insert on the proximal phalanx and the sesamoid bones. They have secondary dorsal expansions into the extensor apparatus, constituting a true hood. The short thumb flexor on the radial sesamoid and the oblique insertion of the adductor on the medial sesamoid actively oppose hyperextension. The adductor pollicis brevis, through its direct insertion on the proximal phalanx near the medial collateral ligament (MCL) and through its dorsolateral expansion, has an active antiabduction action. The same mechanism exists laterally with the abductor pollicis brevis and flexor pollicis brevis, which actively resist adduction.
The lateral stability of the MCP joint is therefore linked to the combined action of the entire capsular ligament and muscle unit, but the muscles alone cannot compensate for a collateral ligament rupture.
Sprains
These injuries are common in sports, including skiing and ball sports, but more recently, they have been seen in Nordic walking with sticks. Sprains of the thumb MCP joint carry serious functional sequelae related to instability of the thumb-finger pinch grip.
Ulnar Collateral Ligament Sprains
The MCP sprain is the primary injury of the upper limb in skiers. There are two mechanisms : either a fall with the thumb “planted” into the snow or a fall with the impact of the stick on the proximal phalanx. This injury is also found in ball sports: volleyball, football and handball. This is correctly known as skier’s thumb. Gamekeeper’s thumb is a chronic ulnar collateral ligament (UCL) injury. The gamekeeper chronically injures the UCL when he kills wounded rabbits by grabbing the animal’s head in the cleft between the thumb and index finger and breaks their necks by pulling forcefully on the legs.
The violent abduction or valgus of the MCP joint causes distension or a rupture of the ulnar capsular ligament complex in its distal attachment on the proximal phalanx in 90% of cases.
The essential problem of the MCL sprain is the absence of spontaneous healing in the case of complete rupture of this ligament, owing to the Stener effect (see Fig. 5.6a ). The adductor muscle, in addition to its insertions on the base of the first phalanx and the internal sesamoid, has a fibrous expansion that joins the extensor apparatus of the thumb by passing over the MCL. In the case of ligament rupture, its proximal portion contracts to lie superficial to the adductor aponeurosis. This aponeurosis comes between the two parts of the ruptured ligament and prevents spontaneous healing even if the thumb is immobilized. Only surgery can restore the original position of the ligament.
The clinical picture is typical: diffuse or localized pain on the medial aspect of the joint, edema, hematoma and loss of function of the thumb.
Simple radiographs (posteroanterior [PA] and lateral views of the MCP joint) should be obtained before any maneuver or investigation of joint laxity to diagnose a possible nondisplaced avulsion fracture. In this case any joint mobilization should be avoided, and treatment includes immobilization for 4 weeks, allowing bone consolidation and stability of the UCL that is attached to it. However, we should abandon strict cast immobilization when the bone fragment is even slightly displaced (<2 mm), because this is associated with a rotation of the fragment. Pseudarthrosis is one of the complications that alters the functional result. It is therefore preferable to provide a surgical fixation of the fragment as demonstrated by Dinowitz et al. If the fragment is small, it is best to resect it and reinsert the ligament on the raw surface of the phalanx caused by the fracture, using a Mitek Minilok anchor (DePuy Synthes).
The main difficulty lies in the evaluation of joint laxity. The clinical examination investigates this laxity bilaterally and comparatively, stressing the MCP joint in valgus. This maneuver is very painful, and local anesthesia is usually necessary. The test is performed in slight flexion to relax the accessory collateral ligament and test the proper collateral ligament. Ligament rupture is determined by a comparative and careful examination, taking into account any constitutional hyperlaxity. Rupture is thus confirmed by an assortment of signs: lateral laxity more than 40 degrees or laxity of 20 degrees greater than the opposite side. The examination also seeks to find a “soft stop” during testing, which translates to a limitation of the maximum deviation by musculotendinous constraint rather than by an effective ligament. This subjective sensation should definitely be compared with the healthy ligament on the opposite side ( Fig. 5.2 ). If the joint is unstable in extension, the accessory collateral ligament is also injured. Rotella Urpi demonstrated, using PA images, that the loss of parallelism between the sesamoid bones and the metacarpal head corresponds to a total rupture of the ligament. This study was supported by Rochet et al., showing that the Stener effect was correlated with displacement of the sesamoid bones.
When the diagnosis cannot be confirmed clinically and using standard dynamic images, ultrasound can be helpful. Jones and coworkers correlated rupture of the UCL visualized on ultrasound with operative findings in 94% of cases, whereas in an emergency department the clinical and radiologic diagnosis was only confirmed in 45% of cases. In another series of 25 cases, Hahn et al. observed 28% false positives due to a Stener effect. When MRI becomes routine in hand trauma, the assessment of injuries will unquestionably be easier because this examination has better results than ultrasound. If in doubt, it is best to proceed with surgical exploration to avoid missing a Stener injury, whose late treatment will be more difficult (with a poorer final result) than for an immediate repair.
On radiographic images the presence of a displaced bone fragment from the ulnar base of the first phalanx consists of a detachment of the UCL at its distal insertion ( Fig. 5.3 ). We can also find a spontaneous palmar subluxation indicating a tear of the dorsal joint capsule. If simple radiographs are normal, comparative images in valgus stress are obtained under local anesthesia. Existence of a large and asymmetric joint widening confirms ligament rupture.
The treatment of an acute MCP sprain, in other words before the 10th day, is based on the clinical and radiologic examination ( Fig. 5.4 ). In the case of a mild sprain, a partial ligament tear without significant laxity or avulsion, immobilization of the MCP joint for 4 weeks in a thumb spica is sufficient, either by plaster or by thermoplastic material (Orfit) ( Fig. 5.5 ). The wrist is left free, as are the IP joint of the thumb and the MCP joints of the long fingers. The first commissure is left open in the functional position of the hand, taking care not to position the MCP joint of the thumb in abduction. This immobilization allows the ligament to heal and provides joint stability.
In severe sprains (significant laxity with rupture of the main UCL), surgery is indicated. Repair should be performed in the first 10 days post trauma to avoid being ineffective. The risk of not treating this condition is progression to joint laxity and osteoarthritis.
Ulnar Collateral Ligament Repair Technique
Repair is done in ambulatory surgery under axillary block and tourniquet. The dissection is performed with loupes. The incision is 3 cm long, dorsoulnar and centered on the MCP joint. The sensory branch of the radial nerve, sometimes responsible for prolonged postoperative dysesthesia, must be marked and protected throughout the operation. The stump of the UCL is frequently found retracted above the proximal part of the hood ( Fig. 5.6a ). The next stage includes partial incision of the adductor aponeurosis 1 or 2 mm from the lateral edge of the extensor pollicis brevis. To facilitate its repair at the end of the procedure (see Fig. 5.6b ), this insertion is tagged using traction sutures. The operative findings may reveal a distal avulsion of the ligament at the base of the first phalanx (55% of cases), tearing of a bone fragment from the base of the first phalanx (30% of cases), or more rarely a full body rupture of the ligament (15% of cases).
We routinely look for a tear in the dorsal joint capsule or a palmar plate injury by reflecting the extensor apparatus. Cartilage injuries are rare.
Simple suture of the ligament in the case of rupture is performed using a slowly absorbable suture.
Distal avulsion at the base of the proximal phalanx is repaired using an absorbable Mitek Minilok anchor. A pilot hole is made with a 2-mm drill at the base of the first phalanx at the insertion of the UCL. This passage is oblique laterally and distally on the phalanx. After insertion of the anchor and verification of its strength by traction on the two threads, both needles are passed into the distal end of the torn ligament, one strand having a direct path, the second passing in a “locking loop.” The two strands are then knotted together (see Figs. 5.6c and d ). This allows the ligament to be put under tension with firm contact onto the base of the phalanx. Some PDS 3-0 reinforcement sutures are placed between the upper edge of the ligament and the dorsal capsule if necessary.
In the case of a bone avulsion, it is best not to pierce this fragment; the sutures should contact the ligament directly ( Figs. 5.7 and 5.8 ). A small Kirschner wire (K-wire) can then complete the assembly by stabilizing the fragment itself if the size allows for it. Excision of a small fragment is sometimes preferable, providing a quality medullary surface for the ligament reinsertion. The risks of pseudarthrosis or residual impingement are therefore absent. Additional sutures are placed between the ligament and surrounding structures . The breach of the dorsal capsule is sutured with an absorbable PDS 4-0 suture to prevent palmar subluxation. Stability of the MCP joint is verified intraoperatively. The hood is repaired with interrupted reversed 3-0 absorbable sutures while keeping the IP joint of the thumb flexed to avoid stiffness of the latter. The skin is closed without drainage, using interrupted sutures or an intradermal overlock suture ( Fig. 5.9 ).
A plaster splint is placed at the end of the intervention on the dressing. On the third day, a thermoplastic splint replaces it, leaving the IP joint of the thumb free, as well as the wrist and MCP joints of the long fingers (see Fig. 5.5a and b ).
More rarely the MCP joint is protected with a temporary arthrodesis wire for 4 weeks. This is recommended when the repair seems fragile or the stability insufficient at the end of the intervention. For professional reasons a buried wire may be useful because it allows the person to go back to work on the 15th postoperative day. This wire is placed in the MCP joint bent at 10 degrees and in slight adduction.
In the immediate postoperative period, active IP mobilization is encouraged to promote excursion of the adductor aponeurosis.
The stabilizing methods (splint, wire) are removed after 4–6 weeks according to the person’s compliance and discipline in respecting the rehabilitation program. Joint mobilization is then allowed, aided by rehabilitation to combat stiffness and limitation of flexion. We recommend nighttime wearing of the splint for another 2 weeks, as well as during activities that load the repair, for its protection and pain relief. A dynamic thumb splint is often necessary to recover full range of motion.
Resumption of activity without restriction usually occurs after 2 months.
Radial Collateral Ligament Sprains
According to published series, sprains of the radial collateral ligament (RCL) are less frequent than those of the UCL (10%–40%) ; however, if they are neglected or poorly treated, they lead to the same complications: instability with pain, palmar dislocation, pronation, loss of strength and osteoarthritis.
The mechanism of injury is a violent adduction of the thumb at the MCP, causing avulsion of the ligament at the base of the proximal phalanx (29%), at the metacarpal head (55%) or more rarely in the middle (16%). The dorsal joint capsule is frequently torn. In addition pronation sets in under the influence of the thumb adductor.
The anatomy of the lateral capsular ligament of the thumb MCP apparatus is not a mirror image of the internal apparatus. The musculotendinous insertions of the short flexor and abductor are weaker than those of the adductor. The stability of the MCP is also ensured by the palmar plate and the sesamoid bones receiving insertions from the deep head of the extensor pollicis brevis on the radial side and from the adductor on the ulnar side. The aponeuroses of the abductor pollicis brevis and adductor pollicis ensure the dorsal stabilization of the extensor pollicis longus. The proper collateral ligament originates dorsally on the condyle of the metacarpal head and obliquely reaches the tubercle of the proximal phalanx in its palmar aspect and comes to affix the accessory collateral ligament. The aponeurosis of the abductor pollicis brevis covers the main ligament. Moreover, the insertion of the abductor pollicis brevis is dorsal to the axis of rotation of the MCP, and this prevents a Stener-like lesion from occurring. On the medial aspect of the joint the adductor insertion is palmar to the axis of rotation, and the ruptured ligament retracts on the proximal and dorsal part of the hood.
Joint rupture of both the collateral ligaments and the dorsal capsule will cause a palmar subluxation of the proximal phalanx, with a pronation effect under the action of the adductor, whose insertions are palmar. In the acute phase the clinical picture is dominated by pain, swelling and joint stiffness. Clinical and radiographic examination under local anesthesia is used to evaluate the degree of instability in adduction and in the anteroposterior (AP) plane. It should be compared with the healthy side. Laxity in adduction greater than 30 degrees and associated with palmar dislocation of more than 3 mm confirms the diagnosis of total rupture and requires surgical intervention. However, in the absence of instability the sprain will be treated by a splint, strictly immobilizing the MCP while allowing active mobilization of the IP.
The surgical approach is dorsolateral, centered on the MCP joint. We must protect the small dorsal sensory branch of the radial nerve. The incision of the hood is partial and proximal to access the lateral and dorsal surface of the metacarpal head. If the ligament rupture is distal, the oblique fibers will be incised to reach the lateral tubercle of the proximal phalanx. We must seek to preserve part of the tendon of the extensor throughout the repair of the ligament to keep the stability of the extensor apparatus and avoid loss of extension of the IP joint.
Whether the rupture of the main ligament is on the head of the first metacarpal or the proximal phalanx, reinsertion is entrusted to a resorbable Mitek Microfix anchor (DePuy Synthes) by drilling a pilot hole using a 2-mm drill. The metacarpal insertion is situated 1 or 2 mm behind the axis of rotation of the condyle, and the phalangeal insertion is 3 to 5 mm from the joint midline, equidistant from the lateral tubercle of the palmar cortex. When the ligament is ruptured in the middle, the repair is performed with PDS 3-0. The dorsal capsule is sutured with PDS 3-0, or if this is impossible, it is attached by one or two absorbable Mitek Microfix anchors, requiring a hole with a 1.3-mm drill.
Postoperative immobilization is entrusted to a static orthosis allowing mobilization of the IP, or more rarely a temporary arthrodesis of the MCP at 10 degrees of flexion with a 12/10 buried Kirschner wire that allows the person to go back to work on the 15th day. This is maintained for a period of 4 weeks. A static splint follows for an additional 2 weeks ( Fig. 5.10 ).
Chronic Laxity of the Metacarpophalangeal Thumb Joint
Primary repair of a ligament rupture should be performed within a maximum period of 10 days. Beyond this the quality of the ligament decreases and the strength of the repair becomes unpredictable. Chronic laxity leads to functional impairment of thumb-to-digit pincer grasp, with pain and loss of strength progressing long-term to osteoarthritis. The treatment of chronic laxity requires ligament reconstruction initially, then arthrodesis when osteoarthritis has developed. Although UCL laxity is the most frequent and incapacitating, RCL laxity nevertheless exists and can be treated either by capsular ligament advancement plasty or by ligamentoplasty.
Ulnar Collateral Ligament Reconstruction Ligamentoplasty
Ligamentoplasty techniques are either passive or active. Sakellarides’ technique is an active reconstruction technique using a duplication of the extensor pollicis brevis, disinserted distally from the proximal phalanx and passed through a transosseous tunnel at the base of this phalanx before being reinserted on the stump of the UCL.
We prefer to leave the extensor apparatus intact and to use Littler’s passive reconstruction technique. Its principle is the reconstruction of the anatomy and biomechanics of the UCL through transosseous tunnels. The approach is the same as for primary surgery, respecting the dorsal ulnar collateral nerve of the thumb. The incision should be long enough to expose the base of the first phalanx and the neck of the first metacarpal. The hood is partially incised in its oblique fibers on the ulnar side of the extensor pollicis longus and then retracted. The UCL is exposed, with its proximal and distal remnants resected. The articular surfaces are examined; the intraoperative discovery of osteoarthritis may indicate a definitive arthrodesis. An AP tunnel is made on the medial and proximal aspect of the proximal phalanx ( Fig. 5.11a ). The two holes made with a small burr are interconnected, taking care not to be intraarticular and preserving a solid bony bridge. A second tunnel is made in the neck of the first metacarpal in a transverse plane perpendicular to the previous tunnel. The awl emerges under the skin at the radial aspect of the metacarpal neck. A small incision using a scalpel blade makes it possible to externalize it. Both tunnels are enlarged with a curette to make room for the tendon graft, especially the metacarpal tunnel, which receives the passage of two tendon strands. The ideal tendon graft is the palmaris longus, taken with a Brandt’s stripper. In the absence of the latter we must choose the plantaris tendon, a toe extensor or half of the flexor carpi radialis.
