Locking compression plate distal ulna hook plate fixation versus intramedullary screw fixation for displaced avulsion fifth Metatarsal Base fractures: a comparative retrospective cohort study

BACKGROUND Intramedullary screw (IMS) fixation was wildly used in fifth metatarsal base fractures (FMBFs) and the results were satisfactory. However, in the comminuted osteoporosis or small displaced avulsion FMBFs, anatomical reduction and stable fixation could not be achieved with IMS. The Locking Compression Plate (LCP) distal ulna hook plate fixation was a novel alternative fixation method. The aim of this retrospective cohort study was to determine if LCP distal ulna hook plate fixation resulted in improved outcomes compared to the traditional IMS fixation in displaced avulsion FMBFs. METHODS Of 43 patients with displaced avulsion FMBFs, 18 patients were treated with LCP distal ulna hook plate fixation and 25 were treated with IMS fixation. The patients were evaluated clinically and radiographically and followed up to 12 months. The surgery time, time for hospital stay, time for weight-bearing, time for bony union, time for return to daily life, pain relief, functional outcome and complications after treatment with LCP distal ulna hook plate fixation or IMS fixation were compared. The functional outcome was assessed by the AOFAS (American Orthopedic Foot and Ankle Society) mid-foot score at 3, 6, 9, and 12 months after surgery. Meanwhile, pain scores were obtained at 3, 6, 9, and 12 months after surgery. RESULTS The two cohorts had similar baseline characteristics. Surgery time was less in LCP distal ulna hook plate fixation cohort compare to IMS fixation cohort (p < 0.0001). Time for partial weight-bearing (p < 0.0001) and full weight-bearing (p < 0.0001) also demonstrated significant improvements in patients with LCP distal ulna hook plate fixation compared to IMS fixation. Patients in the LCP distal ulna hook plate fixation cohort had significantly increased AOFAS at 9 months (p < 0.0001) and 12 months (p < 0.0001) after surgery compared to the IMS fixation cohort. CONCLUSION In this retrospective cohort study, LCP distal ulna hook plate fixation as an alternative fixation method was better therapy for the displaced avulsion FMBFs compared to IMS fixation. LCP distal ulna hook plate fixation had a short surgery time and improved functional performance.