Angulation and Rotation in the Boxer's Fracture
A rotated small finger scissors into its neighbor and weakens grip for good, while a dropped knuckle from angulation rarely costs the patient any hand function.
Key terminology
- Metacarpal neck
- This narrow segment sits just behind the metacarpal head at the knuckle. It is the weakest part of the bone and the usual break point in a punch.
- Boxer's fracture
- This break runs across the neck of the fifth metacarpal after a punch. The knuckle of the small finger sinks and the finger may rotate.
- Scissoring
- The flexed finger crosses over or under its neighbor when the patient makes a fist. In a normal fist all fingertips point toward the scaphoid tubercle.
- Carpometacarpal (CMC) joint
- These joints link the base of each metacarpal to the wrist bones. The index and middle joints are nearly rigid, and the ring and small finger joints move.
- Buddy taping
- The injured finger is taped to the finger beside it so the two move together. It protects the fracture and still lets the hand move.
- Fight bite
- A tooth cuts the skin over the knuckle when a fist strikes a mouth. The wound looks small and can reach the MCP joint.
- Apex dorsal angulation
- The fracture bends so its point faces the back of the hand. The metacarpal head drops toward the palm and the knuckle looks flat.
Takeaways
- The fifth metacarpal neck is the most common metacarpal fracture. It typically follows an axial load on a clenched fist, the punch that gives the boxer's fracture its name. Fifth metacarpal neck fractures make up about 20% of all hand fractures. (Lee et al, Arch Orthop Trauma Surg 2022;142:1705-1713, PMID 35316389; Zachary et al, Plast Reconstr Surg Glob Open 2025;13:e6687, PMID 40230471; Retrouvey et al, Plast Surg (Oakv) 2022;30:6-15, PMID 35096686).
- Rotation is not accepted in any metacarpal fracture. A rotated metacarpal makes the finger scissor over or under its neighbor in a fist. In 98 metacarpal fractures, a quarter had minor rotation under 10° and only 5 had more. Check the nail plates end-on, since a stiff, painful MCP joint can hide rotation, and treat rotational deformity as an indication for surgery. (Royle, J Hand Surg Br 1990;15:124-125, PMID 2307874; Zachary et al, Plast Reconstr Surg Glob Open 2025;13:e6687, PMID 40230471).
- The small finger tolerates far more angulation than the index finger because its CMC joint moves. A mobile fifth carpometacarpal (CMC) joint lets the metacarpal flex at its base and compensate for a tipped head. Grip strength changes only once angulation reaches about 30°. Acceptable limits still disagree, with some authors accepting up to 70° and others stopping at 30°. (Zachary et al, Plast Reconstr Surg Glob Open 2025;13:e6687, PMID 40230471; Hennecke et al, Handchir Mikrochir Plast Chir 2011;43:39-45, PMID 21161877).
- Boxer's fractures angulated up to 70° without rotation do well without reduction. In a 40-patient trial (mean angulation 39°, range 15-70°), a pressure bandage with immediate motion matched 3 weeks in an ulnar gutter cast. A 68-patient trial found soft wrap and buddy taping without reduction noninferior to reduction and casting, with 11 fewer days off work and a flatter knuckle. (Statius Muller et al, Arch Orthop Trauma Surg 2003;123:534-537, PMID 14639483; van Aaken et al, Arch Orthop Trauma Surg 2016;136:135-142, PMID 26559192).
- A wound over the knuckle after a punch is a fight bite until proven otherwise. A tooth can enter the MCP joint and seed septic arthritis, and human bites carry Eikenella corrodens, staph and strep. Treat with a beta-lactam plus a beta-lactamase inhibitor (e.g. amoxicillin-clavulanate). OR debridement for every fight bite is debated, and in 115 patients presentation after 24 hours was the only factor linked to complications. (Kall and Vogt, Chirurg 2005;76:615-625, PMID 15928956; Harper et al, Hand (N Y) 2020;15:647-650, PMID 30808240).
- A boxer's fracture angulates apex dorsal, tipping the metacarpal head into the palm. Volar comminution at the fracture and the pull of the dorsal interossei drive the deformity. The patient sees a sunken knuckle, and the lateral film shows the head flexed toward the palm. (Zachary et al, Plast Reconstr Surg Glob Open 2025;13:e6687, PMID 40230471).
- Buddy taping gives the same function as a plaster cast for an uncomplicated boxer's fracture. In 97 adults, median quickDASH at 12 weeks was 0 in both groups, and the taped group missed a median 0 vs 2 days of work. Pooled studies show no functional gain from surgery, although nonoperative care leaves more residual angulation on film. (Pellatt et al, Ann Emerg Med 2019;74:88-97, PMID 30853124; Chong et al, J Hand Surg Asian Pac Vol 2020;25:281-290, PMID 32723052).
- Angulation is best measured on a true lateral film, and oblique views can read high. In 30 cadaver fractures, oblique radiographs overestimated angulation by up to 35°. A 2026 clinical series found oblique views reliable and close to CT, so the best method is still debated. (Lamraski et al, J Orthop Res 2006;24:37-45, PMID 16419967; Qiu et al, J Hand Surg Glob Online 2026;9:101108, PMID 42733813).