Collateral Ligament Injuries

The wide range of motion of the shoulder and elbow allows for the hands to be placed within a large volume of space. This relative freedom predisposes to hand injury, especially during sports and recreational activities. If enough angular stress is applied to the digits, collateral ligament strain and eventual rupture can occur. Cadaveric studies have shown that the collateral ligament avulses proximally in most injuries, but the VP avulses distally. ^, In addition, the radial collateral ligament (RCL) is more often injured than the ulnar collateral ligament (UCL).

Collateral ligament injuries are graded based on the pathoanatomy of the injury ( Table 32-1 ). Grade I injuries involve a strain to the ligament with microfibril rupture, but the ligament remains intact. Pain is elicited by direct palpation of the involved collateral ligament, and angular stress testing reveals less than 20 degrees of passive instability. In this injury pattern, the joint is stable throughout active range of motion (AROM) and passive range of motion (PROM) testing, and can be managed nonoperatively with a brief period of positioning with an orthosis for pain control, followed by AROM within a week of injury. Buddy-taping or strapping the digit adjacent to the injured digit allows for ROM activities and passive protection of the joint.

Grade II injuries involve a complete rupture or tear of the ligament without instability of the joint during AROM. These injuries may be associated with a small avulsion fracture of the base of the middle phalanx. Stress testing that notes passive instability involving greater than 20 degrees of angular deviation is indicative of a grade II tear, as long as frank dislocation is not identified. These injuries require more aggressive treatment with 2 to 4 weeks of gutter splinting; however, early motion can be initiated if angular stress can be avoided via buddy-straps or under the supervision of a therapist.

Grade III injuries imply complete collateral ligament rupture combined with VP or dorsal capsular rupture. Instability during AROM testing as well as with PROM testing occurs in both lateral and either dorsal or volar stress. Dislocation with either spontaneous or manipulative reduction is likely to be noted with these injuries. Nonoperative treatment requires concentric reduction to be obtained and maintained during ROM activities. Blocking orthoses can be used to prevent subluxation and dislocation by preventing motion in ranges where instability is present. If concentric reduction cannot be maintained, operative treatment is necessary.

Dorsal Dislocations

Dislocations of the middle phalanx dorsally on the proximal phalanx represent 85% of dislocations at the PIP joint. These injuries are the result of hyperextension stress applied to the joint with some element of longitudinal compression directly leading to varying degrees of bony injury. In pure PIP dislocations the VP is commonly ruptured distally; however, on rare occasions it can rupture proximally and, along with the check-rein ligaments, become interposed, thereby preventing attempts at closed reduction. ^, The dissipation of energy through the PIP joint during hyperextension follows a predictable pattern and is subdivided into three groups, proposed by Eaton and Littler. The initial hyperextension results in rupture or avulsion of the thin central portion of the VP along with longitudinal tears in between the fibers of the ACL and PCL. However, the thick, lateral portions of the VP—the so-called critical corner—remain intact. The initial injury to the joint can result in locked hyperextension that must be manually reduced. As the energy increases, the critical corners are injured, and the middle phalanx dislocates dorsally, often held colinearly to the proximal phalanx via intact fibers of the PCL, which are split from the ACL, which additionally remains intact. These type II injuries manifest as a pure dorsal dislocation in which the volar lip of the middle phalanx is perched on the condyles of the proximal phalanx and they may be associated with a small avulsion fracture of the base of the middle phalanx. Type III injuries involve simultaneous collateral ligament injury and some degree of lateral instability, but often manifest as dorsal dislocations ( Fig. 32-4 ).

A, Avulsion fracture of the volar base of the middle phalanx. The volar plate remains attached to the fracture fragment. B, Intra-articular volar fracture with dorsal dislocation. With 40% articular involvement, the middle phalanx displaces dorsally, decreasing tension in the collateral ligament fibers that remain attached to the shaft at the middle phalanx. C, Avulsion fracture of the dorsal lip. The central extensor tendon (CET) remains attached to the fracture fragment. D, Intra-articular dorsal fracture with volar dislocation. The dorsal support is lost, and the middle phalanx displaces volarly. E, Pilon fracture. An axial loading force causes depression of the central articular surface, while the remainder of the articular surface shatters and displaces. F, A lateral compression fracture, caused by axial and angulatory forces, produces depression of the lateral articular surface by the proximal phalanx condyle.

Most dislocations can be treated with closed reduction under digital block followed by an assessment of stability during AROM and PROM. If the joint remains stable up to 25 degrees short of full extension, positioning in an extension block orthosis can be initiated, such as with a figure-of-8 orthosis. These orthoses allow for active flexion of the PIP joint, while preventing subluxation at increasing degrees of extension ( Fig. 32-5 ). Dislocations with small avulsion fractures of the base of the middle phalanx can be treated as though they represent pure dislocations. The splints are eliminated at 3 weeks, and ROM exercises are continued. Reductions that remain unstable or are stable in greater than 25 degrees of flexion, require operative stabilization with volar plate arthroplasty (VPA), extension block pinning, and dynamic external fixation. Irreducible dislocations require open reduction, which can be accomplished via a limited dorsal approach, using a Freer elevator to reduce the interposed soft tissue. A volar approach requires a larger incision in order to mobilize the flexor tendons around the joint, but does allow for concomitant repair of injured volar structures or VPA.

A, Figure-of-eight orthosis. B, Figure-of-eight orthosis prevents hyperextension while allowing full flexion.

The most common complications from dorsal dislocations are residual instability due to inadequate treatment and flexion contracture. A mild flexion contracture is common and has been termed a pseudoboutonnière deformity ; however, it is not a true boutonnière deformity since the DIP joint remains flexible and the central tendon remains attached to the dorsal lip of the middle phalanx. Operative treatment can introduce infection risks from pin tracts and increase soft tissue scarring, which leads to increased stiffness.

Volar Dislocations

In comparison with dorsal dislocations, volar dislocations are rare but more problematic because they frequently involve an avulsion of the central slip at its dorsal attachment. Concomitant unilateral collateral ligament injury can lead to rotatory subluxation of the middle phalanx as it rotates around the intact collateral ligament tether. The difference between these two entities must be elucidated clinically since the treatment algorithm is different. Pure volar dislocations occur with a longitudinal and volar force applied to a semiflexed PIP joint, whereas rotational torque on the joint can lead to rotatory instability. As the joint dislocates volarly, the dorsal capsule tears, allowing the head of the proximal phalanx to herniate in between the lateral band and central tendon. These two structures can form a “noose” around the condyles of the proximal phalanx, preventing reduction via longitudinal traction, which tightens the noose. Reduction can be performed with wrist extension and metacarpophalangeal (MCP) flexion, to loosen the extrinsic and intrinsic extensors, respectively, followed by middle phalanx flexion and dorsal pressure. If closed reduction is unsuccessful after several attempts, open reduction should be performed.

Following reduction, the central slip should be manually tested to assess if avulsion has occurred. If the central tendon is intact, and no subluxation occurs during AROM testing, early ROM exercises can be initiated to prevent stiffness. However, if central tendon injury occurs, positioning the PIP joint in full extension in a gutter orthosis must be performed for 6 weeks to allow for healing. Active DIP motion should be initiated immediately, and this joint should not be immobilized in the orthosis. Operative treatment is indicated for residual instability following reduction and includes pinning and collateral ligament repair for rotatory instability.

Intra-articular Fractures

Fractures involving the distal and proximal articular surfaces of the PIP joint are fairly common, but result from different stresses placed on the joint. Condylar fractures of the proximal phalanx occur with simultaneous lateral and compressive forces, whereas fractures of the middle phalanx occur with compressive and flexion–extension forces. Varying degrees of longitudinal stress applied to the joint can lead to increasing amounts of comminution in the fractures. Fractures about the PIP joint are prone to develop stiffness; thus the goal of treatment is to maximize the stability of the fractures with minimal soft tissue trauma so that active motion can begin quickly.

Volar shearing fractures commonly occur as dorsal fracture–dislocations of the PIP joint. The extent of injury is graded by the amount of articular surface involved, which is directly related to the inherent stability of the fracture. Fractures involving less than 30% of the articular surface are stable and can be treated with extension block positioning and early mobilization. Fractures involving 30% to 50% of the volar articular surface are variably stable and depend on the extent of collateral ligament injury. Fracture fragments larger than 40% of the articular surface generally encompass most of the PCL, rendering the middle phalanx unstable to closed treatment. Fractures with greater than 50% articular surface injury have little collateral ligament stability and have lost the cup-shaped articular surface that provides intrinsic stability to the joint. Nondisplaced fractures and stable displaced fracture patterns are treated with a protective orthosis of the PIP joint while allowing for active MCP and DIP motion. Careful, close follow-up is mandatory to ensure that fracture displacement or joint subluxation does not occur during healing. Orthosis use can be discontinued and AROM/PROM initiated once fracture healing is identified, although protected AROM exercises supervised by a therapist can be considered after 2 to 3 weeks with stable patterns. An orthosis should not be used on fractures for longer than 30 days, nor positioned in greater than 30 degrees of flexion, as flexion contractures are likely to develop.

Unstable fracture patterns require open treatment, and in recent years, numerous techniques have been added to the hand surgeon’s arsenal. Simple large fracture fragments are ideal for open reduction and internal fixation (ORIF) with lag screws or Kirschner’s wires (K-wires) ( Fig. 32-6 ) . This can be performed through a volar approach using Brunner’s incisions and opening the flexor sheath between the A2 and A4 pulleys. The most important aspect of surgical correction is restoration of the volar lip of the middle phalanx, which provides most of the stability that prevents recurrent dorsal subluxation. However, comminution is frequent and can be underestimated on radiographs. If such comminution is encountered, the fracture fragments can be excised and the fibrocartilaginous VP advanced to fill the defect. This VPA can be attached with suture anchors or through pull-out sutures or narrow-gauge wire placed around the extensor mechanism ( Fig. 32-7 ). This procedure should not be attempted when greater than 50% of articular comminution is present because the significant advancement may lead to flexion contracture and the pliable surface of the VP can allow for dorsal subluxation.

Proximal interphalangeal (PIP) fracture treated with open reduction and internal fixation. A, PIP fracture with intra-artricular extension and angular deformity. B, Anatomic reduction with three lag screws.

Volar plate arthroplasty. A, Preoperative lateral radiograph demonstrating impaction fracture of 50% of the volar lip of the proximal interphalangeal joint. B, Intraoperative photograph demonstrating proximal “check-rein ligament” release and distal advancement of volar plate. Flexor tendons are retracted by Penrose drain. C, Final clinical photograph demonstrating volar plate advancement with pull-out button over dorsal surface of digit at distal interphalangeal joint.

For comminuted fractures involving greater than 50% of the articular surface, a relatively new technique known as hemihamate arthroplasty has been shown to be extremely effective ( Fig. 32-8 ). With this procedure, the dorsal lip of the distal articular surface of the hamate, which closely approximates the biconcave fossae of the proximal aspect of the middle phalanx, is harvested and placed in the defect so as to recreate the volar lip and provide stability against dorsal subluxation. This procedure can restore most PIP motion, even when reconstruction is delayed; however, lengthy delays can lead to decreased motion, and most patients have at least a small residual flexion contracture due to the extensive soft tissue mobilization required. Persistent dorsal wrist pain and carpometacarpal (CMC) joint instability have not been reported with this procedure.

Hemihamate arthroplasty. A, Intraoperative photograph depicting large central defect with impaction of the base of the middle phalanx. B, Intraoperative photograph demonstrating preparation of the middle phalanx following osteotomy and contouring of the impacted fracture in order to accept hamate graft. C, Intraoperative photograph demonstrating dorsal view of hamate and outlined portion of bone to be osteotomized and grafted to defect at the base of the middle phalanx. D, Final photograph demonstrating screw fixation of hamate graft to the base of the middle phalanx, effectively reconstituting a normal joint surface.

Another option for large, comminuted volar lip fractures is dynamic external fixation ( Fig. 32-9 ) . Numerous methods have been described; however, the underlying principle is the same; fractures are reduced through traction via ligamentotaxis, and the subluxation is reduced and maintained with the appropriate placement of the external fixation pins. These devices allow for AROM to be initiated immediately within the constraints of the system; however, pin tract infections (≤25%) frequently occur. Typically, these do not result in long-term sequelae if treated appropriately with oral antimicrobials. Additionally, closely monitored radiographic follow-up is required to ensure maintenance of the reduction.

Dynamic external fixation. A, Clinical photograph depicting dynamic distraction of a proximal interphalangeal (PIP) fracture–dislocation. With the use of K-wires, distraction helps to disimpact fracture fragments via ligamentotaxis. Care must be maintained to keep pin sites clean to prevent infection with this technique. B, Clinical photograph demonstrating a compass hinge, a more substantial and supportive form of external fixation. Progressive flexion is achieved via periodic adjustments to the external device. C, Radiograph (posteroanterior view) demonstrating a compass hinge applied to a PIP fracture–dislocation. Frequent radiographs are needed in external fixation systems to ensure maintenance of a concentric reduction and early identification of any fracture displacement.

Fractures of the dorsal lip of the middle phalanx involve an avulsion injury of the central tendon and must be approximated to prevent late boutonnière deformity. Fracture fragments that are reduced within 2 mm of anatomic alignment with an extension orthosis can be treated with full-time immobilization that allows for DIP motion. Failure to reapproximate the central slip of the extensor tendon can lead to imbalance at the PIP and DIP joints, resulting in a boutonnière deformity (flexion contracture of the PIP joint and fixed hyperextension of the DIP joint). Active flexion can be initiated after fracture healing occurs, generally within 4 weeks of the injury. Simple displaced fractures can be treated with pinning or open reduction. Extension block pinning may be performed; however, it is important to place the pins obliquely between the central slip and the lateral bands to prevent scarring, thereby limiting PIP and DIP motion.

Dynamic external fixation is additionally the treatment of choice for patients with comminuted, depressed pilon fractures involving the entire articular surface. These fractures are generally not amenable to open treatment with interfragmentary fixation. Dynamic fixation reduces subluxation and can realign the dorsal and volar fragments although longitudinal traction cannot reduce the depressed articular surface. Interfragmentary pins can be placed to reapproximate markedly displaced fragments, and articular remodeling can occur, leading to a stable joint. However, post-traumatic arthritis and loss of motion are common due to the extensive damage sustained in the initial injury. The use of immediate joint arthroplasty or arthrodesis has been reported sporadically in the literature. Arthrodesis is generally not recommended in the ulnar digits, though it is a useful tool for the index PIP joint, as key pinch (the predominant use of the index digit) is performed in PIP flexion and requires absolute stability of the PIP joint.

Longitudinal, angular force can result in fractures of the condyles of the proximal phalanx and are especially common in athletes. Because these fractures do not involve joint subluxation and ROM can be preserved, they are often misdiagnosed as sprains and patients do not seek treatment until late deformity or persistent pain develop. These fractures can be classified into three categories based on severity. Type I fractures are stable, nondisplaced, unicondylar fractures; type II injuries are unstable, displaced unicondylar; and type III are bicondylar or highly comminuted fractures. Nondisplaced unicondylar fractures can be treated with orthotic positioning and close radiographic follow-up, as displacement is common despite adequate treatment. Unstable fractures require stabilization with either percutaneous pinning or ORIF using screws or a minicondylar plate via a midlateral approach. A percutaneous tenaculum clamp can aid in fracture reduction, and provisional fixation allows for anatomic alignment, even in type III injuries. Dynamic external fixation can play a role in markedly comminuted fractures where fixation cannot be achieved with pins or screws. Provided the articular surface remains aligned, outcomes are generally good, and patients may continue to improve postoperative motion for more than 1 year after surgery due to articular remodeling.