Antegrade versus retrograde intramedullary Kirschner-wire fixation for displaced fifth metacarpal neck fractures: a systematic review and meta-analysis

Abstract

Introduction: This study compares two surgical techniques for the treatment of displaced fifth metacarpal neck fractures, commonly known as "boxer's fractures": antegrade intramedullary fixation (AIMP) versus the retrograde approach (RIMP) using Kirschner wires. The primary objective was to determine whether the antegrade route enables faster functional recovery and a quicker return to work. The review evaluated clinical outcomes including time to return to work, upper extremity function (DASH/Quick-DASH scores), pain level (Visual Analog Scale, VAS), and metacarpophalangeal joint range of motion (ROM). Methodology:
Conducted in accordance with the PRISMA 2020 guidelines, this systematic review and meta-analysis involved a comprehensive search across multiple electronic databases, including PubMed/MEDLINE, EMBASE, Cochrane CENTRAL, Scopus, Web of Science, and Google Scholar. Studies directly comparing AIMP with RIMP were eligible. Risk of bias was assessed using the RoB 2 tool for randomized trials and the Newcastle–Ottawa Scale for observational studies. Due to high pooled heterogeneity resulting from temporally distinct effects, outcomes were stratified into three specific follow-up windows: early (0–8 weeks), intermediate (3–6 months), and long-term (> 12 months). The certainty of the evidence was rated using the GRADE approach. Results
The primary analysis synthesized data from direct head-to-head studies comprising approximately 106 patients (using a pure RIMP comparator), extending to 167 patients in the sensitivity analysis (incorporating crossed/combined RIMP comparators).
Early window (0–8 weeks): The anterograde approach (AIMP) demonstrated substantial advantages. Patients in the AIMP group returned to work significantly faster than those in the RIMP group (approximately 27 days vs. 67 days). AIMP was also associated with greater early recovery of ROM (a mean difference of approximately +20.6^\circ), lower early pain scores, and superior early DASH scores.
Intermediate window (3–6 months): The clinical differences between the two techniques attenuated progressively. By 6 months post-operatively, there were no statistically significant differences between AIMP and RIMP regarding ROM, VAS pain scores, grip strength, or DASH outcomes.
Long-term window (> 12 months): A residual ROM difference of approximately +15^\circ favoring AIMP was observed, though this finding rested solely on evidence using a crossed RIMP comparator, limiting direct comparability.
The overall GRADE certainty of evidence ranged from low to very low across all outcomes, downgraded primarily due to the small number of studies, limited sample sizes, and methodological variations in the comparator techniques. Conclusions: Current evidence suggests that antegrade intramedullary Kirschner-wire fixation (AIMP) confers critical early functional advantages over the retrograde approach (RIMP) for displaced fifth metacarpal neck fractures, characterized by a faster return to work, better early mobility, and less initial pain. However, these clinical benefits tend to converge and equalize by 3 to 6 months post-surgery. The antegrade technique may be preferred when early functional recovery is a clinical priority, such as in manual workers and athletes. Given the sparse long-term evidence and the limitations in current study designs, adequately powered randomized controlled trials with standardized RIMP protocols and prolonged follow-up are warranted.