Chapter 76: Metacarpal And Phalangeal Fractures

Correct fracture terminology aids communication and can help guide treatment. Simple fractures contain two bone fragments, while comminuted fractures have multiple fragments. Spiral fractures have an oblique rotating plane, and greenstick fractures involve only one cortex, occurring in children. Intra-articular fractures extend into a joint surface and may have any number of fragments. Avulsion fractures involve a bone chip caused by distraction forces on a tendon or ligament.1,2

2. Zenn MR, Jones G. Reconstructive Surgery: Anatomy, Technique, and Clinical Applications. St Louis: Quality Medical Publishing; 2012 Fractures that occur in weakened or abnormal bone are classified as pathologic fractures. These include bones weakened by tumor or osteoporosis. Stress fractures occur in normal bone in response to cyclical loading. Greenstick fractures occur in children where the cortices are more pliable and the periosteum is thicker, tending to lead to buckling or unicortical rather than complete fractures. The radiologic appearance of a fracture can be described as transverse, oblique, spiral, longitudinal, or impacted. Spiral fractures have an oblique fracture plane with rotation. Impacted fractures occur secondary to end on stress causing compression.1,2

This fracture represents a Salter-Harris type III injury.1 The Salter-Harris classification applies to fractures that occur at the growth plate (physis) in developing limbs. The classification system is well known and is often tested in examination settings. The most common fracture pattern is a type II injury which involves the metaphysis and physis. These fractures can result in abnormal growth if the epiphyseal plates are permanently damaged (Fig. 76.1).1,2

There is mixed evidence on the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on fracture healing, but a number of animal studies suggest that healing is adversely affected by the administration of NSAIDs. In addition, some clinical studies in humans also support this finding. NSAIDs interfere with the inflammatory stage of bone healing. Based on current evidence, they may be best avoided in patients with acute fractures.1,2 However, many surgeons do routinely prescribe them in patients following hand fractures.3

The safe position for hand splinting involves interphalangeal (IP) joints fully extended, MCP joints flexed to 70 to 90 degrees, and the wrist in slight extension. This places the MCP joint collateral ligaments and IP joint volar plates under maximal stretch and decreases subsequent joint stiffness. It also maximizes function if stiffness persists. The thumb should be abducted from the palm as if holding a beer glass; otherwise it may be more difficult to subsequently regain full range of motion (Fig. 76.2).1,2

The term “boxer’s” fracture is used to describe a fifth metacarpal neck fracture occurring during a punch injury. This is a misnomer because professional boxers rarely sustain such an injury. True boxers are more likely to sustain I II III IV V Fig. 76.1 Salter-Harris classification system of pediatric fractures. (Adapted from PediatricEducation.org. Available at: http://www.pediatriceducation.org. March 10, 2005.) sagittal band ruptures at the MCP joint, resulting in extensor tendon subluxation known as “boxer’s knuckle,” or fractures affecting the index and middle rays.1,2

The Jahss maneuver is used to reduce a metacarpal neck fracture, for example, if malrotation or pseudo- clawing is present. It is performed under local anesthetic block by flexing the MCP joints to 90 degrees and applying force to the metacarpal head in a dorsal direction through the proximal phalanx, while stabilizing the metacarpal shaft. Holding the MCP joint in flexion relaxes the intrinsic muscles while tightening the collateral ligaments and locates the proximal phalanx base under the metacarpal head such that reduction may be achieved (Fig. 76.3).1,2

Most metacarpal fractures display apex dorsal angulation because of the intrinsic muscles. For example, metacarpal neck fractures angulate apex dorsally because the intrinsic muscles lie volar to the axis of rotation 20° -30° 70° -90° 0° -20° Fig. 76.2 Safe position or intrinsic plus position of the hand. (Adapted from Day CS, Stern PJ. Fractures of the metacarpals and phalanges. In: Green DP, Hotchkiss RN, Pederson WC, eds. Green’s Operative Hand Surgery, 6th ed. Philadelphia: Elsevier, 2011.) of the MCP joint, maintaining flexion of the head. The mechanics of phalangeal fractures are more complex with basal fractures of the proximal phalanx tending to angulate apex volar due to the pull of the interossei, whereas middle phalanx fracture angulation depends on the position of the fracture relative to the flexor digitorum superficialis (FDS) insertion.1,2

Fifth metacarpal neck fractures are usually very stable after a punch injury, as the distal fragment is highly impacted. A significant degree of apex dorsal angulation can be tolerated without functional deficit and 40-degree angulation is unlikely to cause a functional problem in the little finger.1 Due to the blunt impact over a flexed MCP joint, there may be an associated injury to the extensor apparatus. Extensor lag is often present initially and is usually due to altered joint mechanics and relative shortening of the bony skeleton versus the tendon. On occasion, the extensor apparatus is also injured, or may be tethered by a bony spicule. Although functional outcomes are good, patients will be left with the appearance of a depressed knuckle. There is no clear consensus on the best nonoperative management of fifth metacarpal fractures and patients tend to do well with either early mobilization with buddy strapping or short-term casting.2

While there can sometimes be a mild degree of pseudo-rotation with fifth metacarpal neck fractures as a result of swelling of the interosseous muscles, malrotation seen in the context of a spiral fracture is much more likely to be of clinical significance. The shortening seen makes true malrotation likely, as shortening along a spiral fracture line will generate rotation. Frank scissoring of the digits is always abnormal. Closed reduction and transverse percutaneous wires may provide relative stability for this fracture, provided that accurate reduction is produced during manipulation and adequate stabilization against the fourth metacarpal A B B Fig. 76.3 A and B, Jahss maneuver. (Adapted from Hamilton SW, Aboud H. Finite element analysis, mechanical assessment and material comparison of two volar slab constructs. Injury 40:397–399, 2009.) is provided. This will require two to three transverse wires through the fifth into the fourth metacarpal. A protective splint is still required for the initial 1 to 2 weeks. Some surgeons find this method unacceptable and prefer not to pass K-wires through the interossei. Internal fixation with multiple lag screws or a lag screw and neutralization plate (not a compression plate) provides a more rigid fixation than K-wires, but at the expense of visible scarring, a palpable plate, and potentially extensive soft-tissue dissection. Early mobilization is preferred following internal fixation to minimize adhesion of gliding surfaces. The choice between multiple lag screws or a screw and plate is determined by the length of the fracture relative to the width and length of the bone. A shorter fracture is unlikely to be stable with screws alone. A noncompressing neutralization plate is applied to support lag screw fixation of a short spiral fracture rather than a compression plate, which would place strain on the lag screw fixation and potentially cause rotation. While intramedullary K-wires can be useful for transverse fifth metacarpal shaft and neck fractures, they cannot control rotation.1–3

metacarpal bases are inherently unstable and require stabilization into the carpus. Fracture dislocations of the fourth and fifth metacarpals may be termed “reverse Bennett fractures” and can occur following axial loading such as during a punch injury. They are relatively common injuries and may be associated with a fracture of the hamate, which can be missed on plain radiographs. The metacarpal bases can dislocate dorsally and should be reduced and stabilized with percutaneous K-wires into the carpus and adjacent metacarpal. A Bennett fracture is a two-part fracture of the first metacarpal base that leaves a small fragment attached to the carpus due to the strong volar beak ligament. The remainder of the metacarpal shaft is displaced and requires reduction and stabilization with K-wires, usually passing into the trapezium and often into the index metacarpal base. The proximal fragment is usually small and stable. It is used as a guide to ensure adequate reduction of the metacarpal base but does not have to be included in the K-wire passes (Fig. 76.4). Rolando fractures are comminuted intra-articular fractures of the first metacarpal. They are treated with either open reduction and plate fixation of larger fragments or closed K-wiring. The second and third carpometacarpal (CMC) joints are very stable and are rarely fractured or dislocated.1–4

A Seymour fracture is an open epiphyseal injury of the distal phalanx. When assessing a child in clinic with a nail bed injury, it is important to look for the presence of a Seymour fracture, which can be mistaken for a simple mallet deformity or soft-tissue swelling after a crush injury. This is an open Salter-Harris type fracture where a nail bed injury and distal phalanx fracture coexist. The clue is that the nail plate usually lies superficial to the nail fold, rather than tucked underneath it. If the fracture is not reduced, there may be subsequent growth disturbance. Furthermore, part of the proximal nail bed may flip into the fracture site, preventing healing or closed reduction. These injuries are more likely to be treated surgically to ensure that the fracture is properly reduced and stabilized, in addition to cleaning and repairing the nail bed.1,2

13. Which one of the following is correct regarding intra-articular fractures of the PIP joint? Not all intra-articular PIP joint fractures are pilon fractures. A pilon fracture occurs following an axial load, causing impaction and comminution of the base of the middle phalanx, often with splaying of the fragments. Treatment options for intra-articular fractures range from simple buddy taping to dynamic external fixators (e.g., Suzuki pins and rubber band system), which use ligamentotaxis to hold the joint space open while allowing movement to encourage a better final joint surface and minimize stiffness.1,2 While a third transverse pin/wire is sometimes needed to control dorsal subluxation of the middle phalanx shaft in flexion, it is often possible to achieve adequate control with two pins/wires. Open reduction and fixation may be required to achieve accurate joint surface reduction through either a volar or dorsal approach. In select circumstances, a bone/cartilage graft may be harvested from the dorsal aspect of the hamate articulation with the fourth/fifth metacarpal bases and used to replace the damaged volar PIP joint surface of the middle phalanx.3 Stiffness is minimized by avoiding additional soft-tissue injury and encouraging early movement; therefore, closed techniques are generally preferred where possible for fractures involving the PIP joint. Minor, stable volar plate avulsion fractures may be managed with either buddy strapping and mobilization or with a short period using a dorsal extension blocking splint and active flexion exercises. Splinting in extension will tend to distract the bony fragment and lead to delayed healing and stiffness.1–3

superficialis (FDS) tendon insertion. Proximal phalangeal shaft fractures usually angulate apex volar because of flexion of the proximal fragment by the interossei. However, middle phalanx shaft fractures can angulate either apex volar or apex dorsal, depending on the location of the fracture in relation to the insertion of the FDS tendon. Oblique phalangeal shaft fractures have a tendency to shorten as the bone fragments slide relative to one another because of the surrounding soft-tissue forces. This can lead to shortening which may interfere with tendon balance. Volar avulsion fractures at the base of the middle phalanx are commonly stabilized by the intact collateral ligaments (Fig. 76.5). While the accessory collateral ligaments attach to the volar plate and therefore cannot exert any stabilizing force on the middle phalanx once the volar plate attachment is avulsed, the true collateral ligaments insert broadly onto the volar 40% of the proximal phalanx. Therefore, if some of the true collateral ligament insertion is preserved, the joint may remain fairly stable, but if more than 40% of the middle phalanx is avulsed, there is no longer any stabilizing force from these ligaments acting on the distal fragment, which then usually subluxes dorsally. Oblique unicondylar fractures tend to be very unstable, so they can commonly lead to lateral deviation or rotational deformities.1–3

articular fracture of the ring finger middle phalanx base. There is angulation with the apex dorsal and there are no visible wounds. stabilizing this fracture. The apex dorsal angulation suggests that the proximal (basal) fragment is being pulled by the insertion of the central slip while the distal (shaft) fragment is being pulled by the strong FDS insertion. This is likely to be unstable after reduction and therefore liable to fall into the same position when the patient flexes the fingers. Closed reduction and percutaneous K-wires should stabilize the fracture adequately. Crossed wires from each midlateral line could be used, either antegrade or retrograde (Fig. 76.6). Opening the digit to use plate fixation increases the soft-tissue injury and the likelihood of postoperative adhesions but could be considered for this fracture if the basal fragment is of sufficient size. Lag screws are not suited to transverse fractures and are used for oblique or spiral fracture patterns. Dynamic external fixators are generally reserved for intra-articular fractures of the phalanges.1–4

sufficient. The pull of the flexor tendons will tend to help maintain the correction, provided an extension block is in place to prevent re-displacement in the early stages. Pseudo-clawing occurs when a basal proximal phalanx fracture unites in apex–volar angulation. This may result in reduced composite flexion of the digit, and also lead to an extensor lag. Tendon adhesions can occur with nonoperative and operative management, but they are most common following open internal fixation. Failed nonoperative management can be salvaged at most stages, but re-manipulation and fixation of the original fracture is easiest in the first 10 to 14 days. There may be a greater risk of nerve injury if care is not taken during closed cutaneous pinning, because the tip of the wire can easily slide off the small, curved phalanx (particularly at the narrow phalangeal neck), whereas the digital nerves can be readily seen and protected during open fixation. There is also a higher risk of infection at pin track sites with external wires than with internal fixation.1