Flexible intramedullary nails for the treatment of metacarpal fractures: A systematic review.

Purpose: Flexible intramedullary nails (FIN) enable minimally invasive and immediate fracture stabilisation, while facilitating early active movement in metacarpal fractures. This systematic review aims to compare locked, non-locked, single, and double FIN and their post-operative outcomes in metacarpal fractures.

Methods: A primary literature search was performed on July 15, 2024. English-language studies investigating acute metacarpal fractures, treated with FIN were included. Analyses included: the 5th metacarpal neck fractures locked vs. non-locked FIN; 5th metacarpal neck fractures non-locked single vs. dual FIN; and the 2nd-5th metacarpal fractures locked vs. non-locked FIN. The National Institute for Health tool and the JBI tool were used to assess study quality for controlled trials and case series, respectively.

Results: Thirteen studies (n = 649 fractures) were eligible, with 12 low risks of bias. There was no difference in overall complication rates between locked and non-locked, and single and double non-locked FIN. Non-locked FIN demonstrated reduced metacarpophalangeal joint penetration (odds ratio (OR): 3.30 (95% confidence interval (CI): 1.23-8.80; p=0.017 and delayed union (OR: 6.95; 95% CI: 1.86-25.97; p=0.004), but increased tendon irritation (OR: 0.19; 95% CI: 0.05-0.83; p=0.027 vs. locked FIN. Overall operative times were lower for single vs. double non-locked nails (mean difference: 9.17; 95% CI: 6.12-12.22; p<0.001).

Conclusions: These findings demonstrate low complication rates and excellent functional results using FIN to fix displaced metacarpal fractures. Although complication profiles are contrasting, there is no clear benefit in using locked or double nails compared to a single non-locked FIN.