Phalangeal Fractures

Introduction

Fractures of the finger bones, known as phalanges, frequently occur and are often seen in emergency departments and clinics. These injuries can affect the proximal, middle, or distal phalanx. In most cases of phalanx fractures, effective realignment can be achieved through non-surgical methods. Timely intervention is crucial to promote healing and restore functionality.

Phalanges of the hand

Clinical Anatomy

The hand's proximal and middle phalanges share a common anatomical structure comprising a head, neck, shaft, and base. Meanwhile, the distal phalanx is characterized by its tuft, shaft, and base divisions. The proximal phalanx is stabilized by surrounding structures, including proper and accessory collateral ligaments, the volar plate, and extensor/flexor tendons. The middle phalanx has two primary insertions: the central slip (part of the extensor mechanism) and the flexor digitorum superficialis (FDS). In the anatomy of the distal phalanx, the distal interphalangeal joint (DIPJ) is surrounded by extensor and flexor tendons, the volar plate, and collateral ligaments. The flexor digitorum profundus (FDP) inserts at the volar metaphysis of the distal phalanx. At the proximal interphalangeal joint (PIPJ), the flexor digitorum profundus and the flexor digitorum superficialis share a sheath. The flexor digitorum superficialis lies on the volar side, while the flexor digitorum profundus is on the dorsal side. As these tendons traverse the PIPJ, the flexor digitorum superficialis bifurcates into two slips, forming the Camper's chiasm, which inserts on the volar aspect of the middle phalanx. This significant anatomical relationship can result in a swan neck deformity, characterized by a hyperextended PIPJ and a flexed DIPJ.

Etiology

Phalangeal fractures of the hand are usually the result of a direct trauma, crush or twisting injury

Epidemiology

Fractures involving the phalanges are prevalent and represent the most common injuries in the body. They are seen in athletic and work-related injuries. They make up 10% of all fractures and contribute to 1.5% of all visits to the Emergency Department (ED). The majority of hand traumas involve the phalanges (46% phalangeal and 36% metacarpal). Among these, the distal phalanx and digits at the border are frequently affected. Males experience these injuries more frequently than females, and notably, the small finger is the most commonly injured

Classification

Fractures of the phalanx exhibit displacement patterns based on the level at which the fracture occurs, influenced by the intricate involvement of soft tissues and tendons.

Distal Phalanx

Fractures in the distal phalanx are typically nondisplaced or comminuted, falling into categories of tuft (tip), shaft, or articular injuries.

• Tuft Fractures: These commonly result from a crushing mechanism, such as striking the fingertip with a hammer. Tuft fractures often lead to open fractures, either due to associated soft tissue injury or nail bed involvement. Even without soft tissue damage, the presence of a nail bed injury classifies the fracture as open.
• Shaft Fractures: Intra-articular fractures are linked to extensor tendon avulsion (Mallet finger) or flexor digitorum profundus tendon avulsion.
  • Mallet Finger: This involves the traumatic loss of terminal extension at the distal interphalangeal joint (DIPJ).
  • Jersey Finger: Resulting from hyperextension, this injury involves avulsion of the flexor digitorum profundus.
• Seymour Fractures: Representing a displaced epiphyseal injury of the distal phalanx, often associated with nail bed injury, Seymour fractures typically result from hyperflexion and present as a mallet deformity with apex dorsal.

Middle Phalanx

Fractures in the middle phalanx lead to apex dorsal or volar angulation based on their location. Apex dorsal angulation occurs when the fracture is proximal to the flexor digitorum superficialis (FDS) insertion, causing displacement by the pull of the central slip. Apex volar angulation results from fractures distal to the FDS insertion. Fractures in the middle third may angulate in various directions or remain undisplaced due to the inherent stability provided by an intact and prolonged flexor digitorum superficialis insertion.

Proximal Phalanx

Fractures in the proximal phalanx exhibit apex volar angulation (dorsal angulation). The proximal fragment flexes due to interossei, while the distal phalanx extends as a result of the central slip.

Clinical Presentation

Patients with metacarpal fractures generally present with

• Tenderness
• swelling
• bruising
• crepitus
• deformity
• restricted motion and instability are common signs of injury