Plastic Surgery for Phalangeal Fracture and Dislocation

Injuries to the phalanges can result in significant loss of hand function. Even the mild "jammed" finger, if not diagnosed and treated promptly, can lead to decreased motion and a poor outcome. This is especially true with injuries to the proximal interphalangeal joint (PIPJ). Fractures of the phalanges, if unstable, need fixation secure enough to allow early motion to prevent adhesion formation and permanent stiffness. ^[7]

Frequency, age, and sex

Because many injuries to the phalanges go unreported, defining a true incidence is difficult. Fractures of the phalanges are surely among the most common in the entire skeleton and may account for as many as 10% of all fractures. A study by Karl et al indicated that phalangeal hand fractures are the second most common upper extremity fractures in the United States, at 12.5 per 10,000 persons annually (behind only distal radius and ulna fractures, at 16.2 per 10,000 persons). The study also found that phalangeal fractures were the most common upper extremity fractures in males and in persons aged 35-49 years. Moreover, the incidence of phalangeal and metacarpal fractures, unlike other upper extremity fractures, was seen to decrease with increasing socioeconomic status. ^[8]

Fractures of the proximal phalanx are the most common phalangeal fractures, followed by fractures of the distal phalanx and then the middle phalanx. The small finger accounts for more than one third of all hand fractures, with an even distribution among the remaining 4 digits. ^[9]

The above statistics were supported by a study by Moura et al of phalangeal fractures in US adults. The report found that the median age at fracture was 45 years, with 65% of the patients being male. Fractures most commonly occurred in the small and ring fingers (26% and 24%, respectively), and fracture incidence was greatest in the distal and proximal phalanges (39% each). In 44% of cases, fracture was sustained in the dominant hand. Blunt trauma, the most common cause of phalangeal fracture in the study, was responsible for 46% of injuries. ^[10]

Fractures and dislocations of the phalanges occur from various mechanisms. In younger patients, these injuries are more likely to be sports-related, while older patients are likely to be injured by machinery or falls. ^{[11, 12]} Crush injuries are common at the distal phalanx, while the PIP joint is usually damaged by an axial blow to the finger.

According to the above-mentioned study by Moura et al of phalangeal fractures in US adults, 18% of fractures in the report resulted from work-related incidents. ^[10]

Stability of phalangeal fractures depends on location, fracture orientation, integrity of the periosteal sleeve, and degree of initial displacement. Distal tuft fractures are usually stable despite comminution. Unicondylar and bicondylar fractures involving the interphalangeal joints are inherently unstable. Displaced fractures involving the diaphyses of the proximal and middle phalanges are also unstable secondary to the pull of the intrinsics and flexor tendons. ^[13] Fractures with an intact periosteal sleeve and no initial displacement are usually stable.

Clinical presentation of finger fractures and dislocations depends primarily on the mechanism of injury. Crushing injuries to the fingertip commonly involve injuries to both the nail bed and the underlying distal phalanx. Injuries at the interphalangeal joints usually present with swelling, ecchymosis, and decreased motion. Any areas of tenderness or crepitus should be palpated. Loss of length or of normal knuckle contour may be indicative of fracture shortening or angulation. ^[14] Deformity may also be present at the joint as well as in the diaphysis of a displaced, unstable fracture.

Transverse fractures in the proximal phalanx assume an apex volar deformity secondary to the pull of the intrinsic tendons on the proximal fragment, which causes the phalanx to flex, and the pull of the extensor tendon on the middle phalanx, which causes it to hyperextend. Unicondylar fractures at the head of the proximal phalanx are common athletic injuries and can often be missed because the athlete can bend his or her finger after the initial injury. Patients present with a history of dislocation reduced by a trainer and present much later if they continue to experience pain and deformity. ^[15]

Fractures of the middle phalanx angulate with the distal fragment dorsally if the fracture is distal to the flexor digitorum sublimis (FDS) insertion and palmarly if the fracture is proximal to the FDS insertion. Distal phalanx fractures, usually secondary to a crush injury, generally do not displace, because both the flexor and extensor tendons insert on the base of the distal phalanx. The nail plate may also provide some support to preserve alignment of the fractured distal phalanx. ^[14] Care must be taken to evaluate the digit for rotational deformity as well. This is best accomplished by flexing the fingers and viewing the nails on end. Subtle overlap may vary from patient to patient; thus, comparison with the contralateral hand can be very helpful.

Classification of these fractures is often done using fracture pattern (transverse, oblique, spira, comminuted), fracture location (head, neck, shaft, intra-articular), and the extent of soft tissue injury (open vs closed). ^[14]

Phalangeal fractures that are nondisplaced or stable following reduction are amenable to closed treatment with splinting and early rehabilitation. Indications for operative treatment of phalangeal fractures include the following:

1. Open fractures

2. Irreducible fractures

3. Unstable fractures

4. Failed closed reductions

5. Displaced intra-articular fractures

Relative indications include the following:

1. Multiple fractures

2. Fractures with bone loss or associated tendon injury ^[14]

3. Fractures with associated tendon injury ^[14]

In general, management of soft tissues is the first priority. Open wounds are common and are an indication for irrigation and debridement. Management of wounds is aided by fracture fixation. Treat fractures with the least invasive method that results in a stable configuration as this allows for early rehabilitation. If stability cannot be achieved or maintained following reduction, some form of fixation is required. The form of fixation chosen should involve the minimum amount of soft-tissue disruption as surgical exposure increases the likelihood of postoperative scar formation between tendon and bone.

There are few places in the body where function and anatomy are as closely intertwined as in the finger. Injuries and subsequent scar formation can upset the delicate balance that normally exists, particularly at the PIPJ and extensor apparatus. Anatomic considerations are based on the level of injury.

Distal phalanx: Terminal extensions of the flexor and extensor tendons insert into the base of the distal phalanx. These tendons can rupture at their insertion or can avulse a fragment of bone. Tuft fractures are commonly associated with injury to the overlying nail bed.

Distal interphalangeal joint (DIPJ): The head of the middle phalanx consists of two condyles that articulate with the base of the distal phalanx. With an axial load, one or both of the condyles may fracture. A closely adherent volar plate provides significant stability. Radial and ulnar collateral ligaments provide resistance to stresses in the coronal plane. ^[16]

Middle phalanx: Sublimis tendons insert along a broad expanse on the volar aspect of the proximal half of the phalanx. The profundus tendon is held tightly in the flexor sheath by the important A4 pulley at the mid portion of the phalanx. The middle phalanx region also contains additional cruciate pulleys (C2 and C3) that are located proximal and distal to the A4 pulley, respectively. On the extensor side, the central slip inserts into the base of the middle phalanx. Lateral bands join over the distal portion of this phalanx to form the terminal extensor tendon. The two lateral bands are stabilized by the triangular ligament, located just distal to the central slip insertion, which prevents volar subluxation of the lateral bands.

Proximal interphalangeal joint (PIPJ): Anatomy at the PIPJ is similar to the DIPJ. The volar plate covers a broad expanse over the joint and is the main stabilizer to joint dislocation. Collateral ligaments are larger at the PIPJ and consist of proper and accessory components.

Proximal phalanx: Sublimis and profundus tendons run together in the flexor sheath at this level. The A2 flexor pulley covers most of the proximal half of the phalanx while the C1 pulley is located more distally. The extensor digitorum communis tendon runs the length of the phalanx and is stabilized by oblique and transverse fibers of the intrinsic apparatus. The lateral bands run from a lateral and volar position at the proximal aspect of the phalanx to a more dorsolateral position at the level of the PIPJ.

No absolute contraindications exist in the management of these injuries. Studies have shown that even in the face of extensive soft tissue damage (open fractures), achieving solid internal fixation allows early mobilization and is of great importance. ^{[17, 18]} Relative contraindications include the use of internal fixation in a reduced and stable fracture or plating a fracture that can be managed with a less invasive fixation technique.