Surgical Treatment of Zone 1 Fifth Metatarsal Base Fractures Using the Locking Compression Plate Distal Ulna Hook Plate

Background: The distal ulna hook plate was recently introduced for the treatment of fifth metatarsal base fractures, but no special articles have reported the surgical results of the plate fixation of displaced or comminuted fifth metatarsal base fractures in zone 1, which are the most common forefoot fractures. Methods: Twenty-one patients with Lawrence classification zone 1 fifth metatarsal base fractures with extra-articular displacement greater than 2 mm (n = 13) and intra-articular displacement fractures (n = 8) were included in the study. Patients were treated with the distal ulna hook plate. Patients were evaluated clinically and radiographically, and the functional outcomes were graded using the American Orthopaedic Foot and Ankle Society midfoot scoring system. Time to union and return to pre-injury levels of activity were calculated. Results: Mean American Orthopaedic Foot and Ankle Society midfoot scores were 42.25 points (range, 27-55 points) preoperatively and 93.16 points (range, 87-100 points) 1 year postoperatively. Mean time to complete union was 61.9 days (range, 52-85 days). Nineteen patients reported returning to previous activities of daily living at a mean of 79.8 days (range, 59-91 days). Two patients showed radiographic signs of mild degenerative changes and noted mild pain, and one patient experienced hardware irritation. Conclusions: The distal ulna hook plate might be considered an effective surgical method for zone 1 displaced fifth metatarsal base fractures or multifragmentary, osteoporotic fifth metatarsal base fractures.