A healthy 22-year-old right-handed man presents to the ED with right hand pain. He reluctantly endorses punching a concrete wall with an ungloved fist. On exam, the patient is holding his hand with fingers in partial flexion. There is mild swelling over the third through fifth MCPs with mild erythema and intact skin. Neurovascular exam is normal. Plain films were obtained.
What is the Diagnosis?
Boxer’s Fractures are a very common injury seen in the ED. Highest incidence are in men 10-19 years followed by men 20-29 years. The two most common mechanisms of injury are falls or direct blows with high axial loads (i.e. punching a fixed, inelastic object). Interestingly, despite the name, these fractures are not typically seen in experienced boxers, as boxing training aims to teach one to lead with the first and second knuckles, aligning the forces of impact into an axial load that transmits and distributes force through the larger bones and joints of the forearm and upper arm. Studies have suggested roughly 30% of hand fractures are metacarpal fractures and they account for nearly 19% of ER fracture visits. The metacarpal neck is the most commonly fractured site. The fifth metacarpal is the most commonly fractured metacarpal. Fractures to the first metacarpal are less common and are often managed operatively. First metacarpal fractures include Bennett’s fractures (fracture-dislocation of the base of the first metacarpal), and Rolandos fractures (comminuted version of Bennett’s fracture) and can also occur as a result of an axial load mechanism such as punching.
Typical symptoms include tenderness or pain focally over the distal metacarpal. Physical examination should include careful inspection for possible “fight bites” given the common potential mechanism of injury. Comparing to the uninjured hand can help highlight distorted anatomy. Evaluate for possible rotational misalignment of the metacarpals by observing convergence of the finger tips with flexed MCPs and PIPs. Note that in this position, phalanxes should point to the scaphoid. Evaluate for extensor mechanism injuries. Due to the intrinsic pull of the interosseus muscles, metacarpal neck fractures typically result in dorsal angulation of the apex of the fracture, resulting in a clinical appearance of a depressed MCP joint.
Obtain AP, oblique, and lateral hand films
Indications for CT:
Inconclusive plain films with high clinical suspicion for injury
Complex fractures of metacarpal head
Multiple CMC dislocations
Given the mechanism, skin break or lacerations over the knuckle may not only represent a potential open fracture, but should also lend themselves to a high degree of suspicion for a “fight bite,” with associated microbiological concern, and managed accordingly. Other fight-related injuries should also be considered and evaluated for as well.
Not all metacarpal fractures are managed the same. Important factors in management include degrees of shaft angulation and length of metacarpal shaft shortening, dependent on which metacarpal is injured, neurovascular status, and whether the injury is open or closed.
|METACARPAL||ACCEPTABLE DEGREE OF SHAFT
Unacceptable degree of angulation (per table above)
Unacceptable shaft shortening >5 mm regardless of metacarpal
Rotational deformity of any digit >10 degrees
Intraarticular fracture or involvement of metacarpal head
Most first metacarpal fractures (Bennett’s and Rolando)
Consider an ulnar nerve block!
Using a c-arm for real-time X-ray feedback may be helpful.
Jahss technique: 90 degrees flexion of MCP and the PIP (AKA 90-90 approach). Apply dorsal pressure to the proximal phalanx while stabilizing metacarpal shaft.
Ulnar gutter for immobilization of the fourth and fifth metacarpals
Volar splint for immobilization of the second and third metacarpals.
Referral to hand surgeon for follow-up
Take home points:
Boxer’s Fractures are a common injury, most often seen in young men.
Consider wounds associated with these fractures as potential fight bites given the mechanism
The more radial the metacarpal involved, the less degree of angulation is acceptable without surgical intervention, while there is no degree of acceptable malrotation
Faculty Reviewer: Dr. Nicholas Asselin
Nakashian et al. Incidence of metacarpal fractures in the US population. Hand. 2012. 7(4):426.
Ashkenaze and Ruby. Metacarpal fractures and dislocations. Orthopedic Clin North Am. 1992 23:19.
Haughton et al. Principles of hand fracture management. Open Orthop Journal. 2012. 6;43-55.