Motorized Internal Limb-Lengthening (MILL) Techniques Are Superior to Alternative Limb-Lengthening Techniques: A Systematic Review and Meta-Analysis of the Literature.

Background: The field of limb lengthening has undergone substantial advancement in recent years with respect to the subjective patient experience, the rate of surgical complications, and the time required to achieve regenerate consolidation. We aimed to assess the performance of motorized internal limb lengthening (MILL) devices when compared with alternative methods of limb lengthening through systematic review and meta-analysis. Methods: Studies comparing MILL methods with alternative forms of limb lengthening were included for systematic review. Medical Subject Headings (MeSH) terms, specifically "PRECICE," "STRYDE," "FITBONE," "limb lengthening," "Ilizarov," "distraction osteogenesis," and "motorized internal limb lengthening," were used to search a number of electronic bibliographic databases, including PubMed, the International Clinical Trials Registry Platform (World Health Organization), the Cochrane Library, ClinicalTrials.gov, and the EU Clinical Trials Register. The primary outcome measures were time to union and total length (centimeters) achieved. Kaplan-Meier survivorship curves were generated, and the 2-sample t test with equal variances was utilized to compare groups. Secondary outcomes including problems, obstacles, and sequelae were compared using a random-effects meta-analysis. To detect any evidence of publication bias, the Egger test for small-study effects was used. A number of bone-healing indices, when reported, were compared between groups. Results: A total of 143 limbs were lengthened using MILL techniques. These were compared with 98 limbs that were lengthened with the use of alternative techniques. The MILL cohort was found to have significantly fewer problems (p < 0.001; relative risk [RR] = 0.31; 95% confidence interval [CI], 0.19 to 0.52) and sequelae (p = 0.002; RR = 0.57; 95% CI, 0.40 to 0.81) on random-effects meta-analysis. Both deep and superficial infectious complications were fewer for MILL procedures across all of the studies. Conclusions: MILL is associated with fewer complications than alternative methods of limb lengthening. Because of the advancements in the field of limb lengthening toward fully implantable remote-controlled internal limb-lengthening devices, MILL techniques are likely to dominate the field of limb lengthening in the foreseeable future. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.