Intra-articular Fracture at the Base of the Proximal Phalanx in the Index Finger Following a Punching Mechanism in a Patient with an Ipsilateral Ulnar Claw Deformity: A Case Report

INTRODUCTION: Altercations involving punching forces constitute 18.5% of all hand injuries. Intra-articular proximal phalanx base fractures of the index finger only account for 0.5% of all hand fractures. There is a paucity of ulnar claw deformities discussed in the literature, likely because ulnar neuropathies rarely remain untreated long enough to progress to deformity. We present the first reported case of a chronic ulnar claw deformity leading to an uncommon finger fracture pattern through an altered punching mechanism. CASE REPORT: A 62-year-old right-hand dominant male who presented to the emergency department for a behavioral health examination was found to have an intra-articular fracture at the base of the proximal phalanx in the left index finger. This occurred secondary to an altered punching mechanism influenced by an existing ulnar claw deformity. Radiographs of the left hand revealed a simple, non-angulated, and minimally displaced oblique fracture at the base of the proximal phalanx. Diffuse edema and ecchymosis of the index finger and gross hypothenar, intrinsic, and adductor pollicis muscle atrophy were observed. A single source of ulnar clawing could not be elicited on the clinical examination alone. Management involving non-operative treatment with buddy-tape and non-weight bearing for 2 weeks was instituted. The patient did not follow-up with orthopedics for repeat evaluation. CONCLUSION: This case demonstrates a unique fracture that likely occurred due to altered punching biomechanics from an ulnar claw deformity. The authors recommend that clinicians use their best judgment when comparing clinical findings to seemingly benign imaging studies. Early immobilization is crucial to prevent collapse and surgical intervention of intra-articular phalangeal fractures.