Musculoskeletal · Hand and Wrist Injuries
The facts most likely to be tested
A Boxer fracture is defined as a fracture of the neck of the fifth metacarpal resulting from a direct axial load, typically a clenched-fist strike against a hard object.
Physical examination reveals dorsal angulation of the fracture fragment and loss of the normal prominence of the fifth metacarpal head (knuckle).
Initial diagnostic evaluation requires anteroposterior, lateral, and oblique radiographs of the hand to confirm the fracture and assess the degree of angulation.
The ulnar gutter splint with the metacarpophalangeal (MCP) joints flexed at 70–90 degrees is the standard initial immobilization technique.
Acceptable angulation for the fifth metacarpal neck is generally less than 40 degrees, as the carpometacarpal joint has significant compensatory mobility.
Patients must be screened for a fight bite injury, characterized by a laceration over the MCP joint, which requires prophylactic antibiotics (e.g., amoxicillin-clavulanate) due to high risk of *Eikenella corrodens* infection.
Surgical consultation for open reduction internal fixation (ORIF) is indicated for fractures with malrotation, excessive angulation, or intra-articular involvement.
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A 22-year-old male presents to the emergency department with right hand pain after punching a wall during an argument. On physical exam, there is swelling and tenderness over the ulnar aspect of the dorsal hand, and the fifth metacarpal head is not palpable. There is no overlying skin laceration. Radiographs demonstrate a fracture of the fifth metacarpal neck with 30 degrees of volar angulation.
What is the most appropriate initial management for this patient?
Ulnar gutter splinting
The patient presents with a classic Boxer fracture with acceptable angulation (<40 degrees), which is managed conservatively with an ulnar gutter splint.
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Etiology / Epidemiology
Occurs in young males following an axial load injury to a clenched fist against a hard object.
Clinical Manifestations
Presents with loss of knuckle prominence and ulnar gutter splint indication.
Diagnosis
Confirmed via X-ray showing fracture of the 5th metacarpal neck.
Treatment
Managed with ulnar gutter splint; surgical referral if angulation exceeds 40 degrees.
Prognosis
Most heal well with conservative management; malrotation is the primary functional complication.
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Epidemiology & Etiology
Commonly seen in young males after striking an object with a closed fist. It is the most frequent metacarpal fracture, typically involving the 5th metacarpal.
Pertinent Anatomy
The fracture occurs at the metacarpal neck, the weakest point of the bone. The volar angulation is characteristic due to the pull of the interosseous muscles.
Pathophysiology
Direct impact causes an axial load transmitted through the metacarpal shaft. The force results in a transverse fracture with volar angulation of the distal fragment. The extensor tendon mechanism often contributes to the displacement pattern.
Clinical Manifestations
Patients present with pain, swelling, and ecchymosis over the dorsal hand. The loss of knuckle prominence is the pathognomonic physical exam finding. Check for rotational deformity by ensuring fingers point toward the scaphoid during flexion.
Diagnosis
The X-ray (AP, lateral, and oblique views) is the gold standard for diagnosis. Measure the angulation on the lateral view; angulation >40 degrees generally requires reduction.
Treatment
Initial management is an ulnar gutter splint with the MCP joint flexed at 90 degrees. Do not use if there is an open wound (human bite), which requires prophylactic antibiotics (e.g., amoxicillin-clavulanate). If angulation is excessive, perform closed reduction under local anesthesia.
Prognosis
Most fractures heal with conservative management and functional splinting. Malrotation is the most significant complication, requiring surgical correction to prevent permanent grip impairment.
Differential Diagnosis
Bennett fracture: intra-articular fracture of the 1st metacarpal base
Rolando fracture: comminuted intra-articular fracture of the 1st metacarpal
Metacarpal shaft fracture: involves the diaphysis rather than the neck
Carpometacarpal dislocation: involves joint instability rather than bone fracture
Soft tissue contusion: lacks radiographic evidence of cortical disruption