Intra-articular Fractures of the Proximal Interphalangeal Joint

18 Intra-articular Fractures of the Proximal Interphalangeal Joint

David J. Shewring

Abstract

Intra-articular fractures of the proximal interphalangeal joints (PIPJs) occur frequently through a variety of mechanisms. The PIPJ is a particularly important joint for the function of the hand and is unforgiving. Condylar fractures are unstable and so are difficult to treat nonoperatively, although success may be more likely in children due to the thicker periosteum. Most will need operative stabilization. This is best achieved with a single lag screw through a lateral approach, after which the finger can be mobilized immediately. These fractures can still be taken down several weeks after injury and although the results are not as good as when treatment is undertaken earlier, this is still better than the prospect of an intercondylar osteotomy. Fractures of the base of the middle phalanx include dorsal and palmar lip fractures, die-punch injuries, and pilon fractures. Dorsal lip fractures can be treated as for a Boutonnière injury if the fragment is very small, or internally fixed if the fragment is larger. Small palmar lip avulsion fractures are very common. They are stable and can be treated with immediate mobilization. Larger fractures may be less stable but can be treated with extension block splintage or a transarticular wire, depending on patient compliance. A dynamic external fixator can also be used. Die-punch and pilon fractures represent some of the greatest challenges in hand surgery. Selected cases are amenable to internal fixation. A knowledge of the mechanics through which these fractures are created and careful analysis of the fracture pattern will facilitate this. Dynamic external fixation can also be used. Osteochondral hemi-hamate autografting can be used for acute cases and for late reconstruction.

Keywords: fracture, phalanges, internal fixation, nonoperative, condylar, pilon, die-punch, avulsion, hand therapy, lag screws, K-wires, malunion, flexion contracture, comminution

18.1 Trauma Mechanism

Fractures affecting the PIPJ are common.1 The PIPJ is particularly unforgiving after injury, which is reflective of the complicated bony contours of this joint as well as the complex soft tissue arrangements surrounding it. Stiffness following significant injury, particularly loss of full extension, is common.

The history will give an indication of the configuration of the injury. This will reflect the variety of mechanisms through which injuries to the PIPJ occur. Hyperextension injuries to the joint may damage the palmar plate. A forced flexion injury with simultaneous extension of the joint may disrupt the extensor mechanism, particularly the central slip. Twisting injuries from a dog lead or horse’s reigns may damage the collateral ligaments. The patient often gives a history of a dislocation, reduced at the time of injury. This may have been the case, but the same history of “dislocation” is often given when a displaced fracture has been reduced at the time of injury, or immediately after a rupture of the central slip of the extensor when the patient moves the finger from flexion into extension, often with a “clunk.”

An axial force through an extended digit, such as when miscatching a ball, or tripping up the stairs is transmitted through the proximal phalangeal head and into the base of the middle phalanx and may result in a condylar or pilon fracture. Various patterns of fracture can be formed. If no central element forms, then a T-shaped fracture pattern may arise resulting in a pilon fracture ( Fig. 18.1a). If a central element is formed, then a die-punch fracture is created ( Fig. 18.1b).

18.2 Classification

• Condylar fractures

• Middle phalangeal base fractures

Dorsal lip fractures

Palmar lip fractures with or without dislocation

• Pilon fractures

• T-shaped fractures

• Die-punch (i.e., comminuted) fractures

18.3 Clinical Signs and Tests

The finger will be painful and will often have a fusiform swelling and reduced range of movement of the joint. If a displaced fracture is present, there may be deformity.

18.4 Investigatory Examinations

The primary investigation is a plain radiograph with anteroposterior and lateral views of the joint. It is important that specific views of the injured digit are obtained, rather than radiographs of the whole hand which are commonly requested in the emergency department. It is also imperative that a true lateral view of the joint is obtained. If the view is oblique, then a subluxation of the joint may be missed ( Fig. 18.2). If slight incongruency of the joint is present after reduction of a dislocation, this is always significant and may herald soft tissue interposition into the joint requiring exploration. Occasionally, a computed tomography (CT) scan will provide useful information; if the plain radiographs are of good quality, this would be unusual.

Fig. 18.1 An axial force through the digit may result in a fracture of the base of the middle phalanx. If no central element forms, then a T-shaped pilon fracture is created. (a) If a central element forms, then a die-punch fragment is created. (b) For this to occur, the two lateral columns have to separate, although one column may remain intact. (c) The die-punch fragment can be accessed by an approach via the fractured column, in this case dorsally. (d) An example whereby the die-punch has been reduced by hinging the dorsal column fracture on the central slip and then internal fixation using a lag screw (e).

Fig. 18.2 A substandard radiograph of the PIP joint. The obliquity of the view may result in the dislocation being missed.

18.5 Evidence

18.5.1 Condylar Fractures

Condylar fractures of the phalanges are relatively common. They may occur as the result of avulsion through the collateral ligament or as the result of axial loading of the digit resulting in tilting at the joint and a shearing stress. Most of these fractures will require stabilization since the oblique fracture pattern of the typical condylar fracture renders them inherently unstable ( Fig. 18.3). Malunion will result in deformity and articular incongruity ( Fig. 18.4) with the possibility of late osteoarthrosis. If axial loading is central and high energy, they may be bicondylar ( Fig. 18.5). The articular surface may be buckled and the subchondral cancellous bone compressed ( Fig. 18.6), making accurate reduction difficult. In these cases, it is as well that the surgeon is prepared and the patient warned.

Fig. 18.3 (a, b) A condylar fracture stabilized with a single lag screw. The oblique fracture pattern makes these injuries inherently unstable.

Fig. 18.4 Malunion of a condylar fracture resulting in deformity and articular incongruity.

If the fracture presents in an undisplaced position and nonoperative treatment is initially embarked on, close monitoring with weekly radiographs will be required, as these fractures will frequently displace. Undisplaced condylar fractures in children may be more stable, due to the thickness of the periosteum, which may be intact, but vigilance is still necessary.

Displaced condylar fractures will require open reduction and internal fixation. If there is marked displacement ( Fig. 18.7), then there will be significant soft tissue disruption, with tearing of the periosteum and this will herald instability. It is unlikely that an acceptable result would be obtained by nonoperative means and internal fixation is the method of choice for these fractures.²

18.5.2 Middle Phalangeal Base Fractures

Dorsal Lip Fractures

These fractures occur as the result of an avulsion of the insertion of the central slip of the extensor mechanism.

Palmar Lip Fractures

Palmar Lip Fractures without Dislocation

Small avulsion flake fractures of the palmar lip ( Fig. 18.8) occur as the result of hyperextension injuries, often during sports such as netball or basketball and are as the result of traction through the palmar plate. They most commonly affect the long finger and the prognosis is generally good,3 particularly as they tend to occur in a younger age group. Simple advice and early mobilization is all that is usually needed.^3,4

Fig. 18.5 (a–c) Bicondylar fractures may result from a centralized axial force through the digit.

Fig. 18.6 (a, b) High-energy injuries may result in comminution, crushing, and deformation of the fragments precluding an accurate reduction.

Palmar Lip Fractures with Dislocation

Dorsal fracture dislocations of the middle phalangeal base ( Fig. 18.9) are relatively common and occur as the result of an axial injury to the digit, either during contact sport, miscatching a ball, or when tripping while ascending the stairs. It is imperative that a true lateral of the joint is obtained ( Fig. 18.2). The stability of the joint is governed by how much of the articular surface of the base of the middle phalanx has been fractured, although this is not exact. If less than 30% of the base has been fractured, then the joint will usually be stable. Between 30 and 40%, the joint may be stable but has a tendency to instability. Over 40% and the joint will be unstable.⁵ Assessing the congruency of the joint is important. If, on a true lateral radiograph, the intact dorsal base of the middle phalanx forms a “V” with the dorsal aspect of the proximal phalangeal head, then the joint is incongruent and this should be corrected. If the joint is slightly subluxed, this will herald instability. These injuries are readily reduced closed with traction and flexion of the joint.