Weightbearing After Medial Meniscus Root Repair: A Cadaveric Study Analyzing the Integrity of Meniscus Root Repairs Subjected to Physiological Cyclic Loading

Background: Meniscus root tears, if untreated, can lead to rapid osteoarthritic changes. Effective repairs are essential to maintain meniscal function and prevent degeneration. Hypothesis/Purpose: This study aimed to evaluate the integrity of medial meniscus (MM) root repairs performed using an inlay transosseous single-tunnel repair technique. It was hypothesized that such repairs could withstand physiological cyclic weightbearing in full extension. Study Design: Controlled laboratory study. Methods: Fifteen fresh-frozen cadaveric knee specimens (mean age, 67 ± 14 years) with intact collateral ligaments, cruciate ligaments, and meniscocapsular attachments were used. Diagnostic arthroscopy confirmed MM integrity in 11 specimens, which then underwent root detachment and repair using a transosseous single-tunnel technique. Metallic tracers were placed into the medial tibial spines and posterior horns of the medial menisci. Specimens were loaded in full extension using a tensile testing machine under 4 conditions: intact, cut, repaired, and repaired after cyclic loading (1700 N for 250 cycles). Fluoroscopic imaging, performed with standardized, reproducible positioning, documented meniscal displacement with known resolution. ImageJ software was used to calculate displacement normalized to tibial plateau width. Repair integrity after cyclic loading was assessed by arthroscopic inspection. Results: All specimens showed intact MM root repairs after cyclic loading. Significant meniscal displacement was observed between intact and cut states ( P = .044), intact and repaired states ( P = .020), and intact and repaired-cycled states ( P = .036). No significant difference was found between repaired and cut or between repaired and repaired-cycled states ( P > .05). Repairs did not catastrophically fail but demonstrated significant plastic deformation. Conclusion: MM root repairs using the transosseous single-tunnel technique do not withstand simulated physiological weightbearing in full extension and demonstrate meniscal displacement similar to that of the unrepaired (cut) state in a cadaveric model. Clinical Relevance: This study suggests that MM root repairs with this technique allow unacceptable displacement under physiological loads. These results provide insight into the biomechanical performance of meniscus root repairs and underscore the importance of establishing appropriate postoperative weightbearing protocols.