Comparative Efficacy and Safety of Intramedullary Lengthening Nails vs. Alternative Techniques for Femoral Limb Lengthening: A Systematic Review and Meta-Analysis.

Background: Limb lengthening procedures are performed for various indications, including limb length discrepancies (LLDs) and short stature. This systematic review and meta-analysis compares the efficacy and safety of the newer motorized intramedullary lengthening nails (MILNs) with the traditional alternative techniques (ATs) for femoral limb lengthening.

Methods: We conducted a comprehensive literature search in the Medline, Embase, Cochrane, Web of Science, and Scopus databases, inclusive of all dates through July 1, 2023, and without language restrictions. Factors mediating outcomes included problems, obstacles, complications, total adverse events, healing/consolidation index, time to full weight-bearing, lengthening accuracy, percentage of lengthening goal achieved, and duration of hospital stay. Effect sizes were quantified using STATA 17.0. Statistical algorithms employed were random effects model standardized mean differences (SMDs) for continuous outcomes and log risk ratios (RRs) for dichotomous outcomes, both with 95% confidence intervals (CIs).

Results: Our meta-analysis included 10 studies comparing MILN with AT: 180 femurs in the MILN group and 160 femurs in the AT group. This was exclusively comprised of retrospective cohort studies. When compared with AT, limb lengthening procedures utilizing MILNs had significantly lower problems (log RR, -1.35; 95% CI, -1.93 to -0.77; p < 0.001), complications (log RR, -0.56; 95% CI, -0.90 to -0.22; p = 0.001), and total adverse events (log RR, -0.69; 95% CI, -1.17 to -0.21; p = 0.005), as well as a superior bone healing index (SMD, -0.80; 95% CI, -1.32 to -0.28; p = 0.003). However, no significant differences were found in obstacles, percentage of lengthening goal achieved, lengthening accuracy, time to full weight-bearing, and duration of hospital stay.

Conclusion: Limb lengthening with MILNs vs. AT may offer more favorable patient outcomes, lowering risk for problems, complications, and total adverse events, while optimizing the bone healing/consolidation index. However, the limitation of nonrandomized retrospective studies and high heterogeneity should be acknowledged.

Level of evidence: Level II (meta-analysis of cohort studies). See Instructions for Authors for a complete description of levels of evidence.