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There is growing evidence that medial meniscotibial ligament (MTL) deficiency and medial meniscus extrusion may precede the development of some medial meniscus posterior root (MMPR) tears. However, no study has investigated the biomechanical consequences of MTL deficiency on the MMPR.(1) MTL deficiency leads to increased medial meniscus extrusion, (2) increased medial meniscus extrusion is correlated with increased compression and shear forces at the MMPR, and (3) MTL repair restores medial meniscus extrusion and MMPR forces to native levels.Controlled laboratory study.Fifteen pairs of fresh-frozen cadaveric knees were tested. Specimens were organized into 3 groups according to a balanced incomplete block design: (1) native, (2) MTL deficiency, and (3) MTL repair. For the MTL deficiency group, a 3-cm deficiency in the MTL was developed under direct arthroscopic visualization. Specimens in the MTL repair group underwent a 2-anchor repair that compressed the joint capsule to the proximal tibia. All specimens were biomechanically tested in full extension with a tensile testing machine. The specimens underwent cyclic loading for 10,000 cycles at 1 Hz and compression of 20 to 500 N, with a 500-N compressive force applied for 30 seconds after the 0th, 100th, 1000th, and 10,000th cycles. Ultrasound was used to measure medial meniscus extrusion. Shear and compressive forces at the MMPR were measured with a 3-axis sensor installed inferior to the MMPR tibial attachment.Medial meniscus extrusion was significantly increased in the MTL deficiency group compared with the native group (0th: 1.6 ± 0.1 mm vs 1.2 ± 0.1 mm, P < .05; 100th: 2.2 ± 0.2 mm vs 1.5 ± 0.2 mm, P < .05; 1000th: 2.8 ± 0.2 mm vs 1.8 ± 0.2 mm, P < .05; 10,000th: 3.5 ± 0.3 mm vs 2.1 ± 0.2 mm, P < .05). Compression root force was significantly increased in the MTL deficiency group compared with the native group at all cyclic loading points (0th: 21.7 ± 12.8 N vs 13.6 ± 2.4 N, P < .05; 100th: 18.9 ± 11.0 N vs 12.1 ± 7.5 N, P < .05; 1000th: 16.5 ± 9.9 N vs 11.2 ± 7.5 N, P < .05; 10,000th: 12.6 ± 8.6 N vs 9.0 ± 6.9 N, P < .05). Root shear force was significantly increased in the MTL deficiency group compared with the native group at the 0th (17.5 ± 2.5 N vs 13.6 ± 2.4 N, P < .001) and 100th (16.2 ± 2.6 N vs 12.1 ± 2.2 N, P < .001) cycles. Medial meniscus extrusion, root shear force, and compression root force of the MTL repair group were not significantly different from the native group for all cyclic loading points.Medial MTL deficiency led to increased medial meniscus extrusion as well as greater compression and shear forces at the MMPR compared with the intact and repaired MTL states, suggesting that MTL deficiency may predispose the MMPR to injury in a cadaveric model.MTL deficiency predisposes one to medial meniscus extrusion and MMPR tears. Subsequently, MTL repair can potentially correct medial meniscus extrusion and normalize forces at the MMPR. [ABSTRACT FROM AUTHOR]

Background: Injury to the ulnar collateral ligament of the elbow is common among overhead throwing athletes and can result in significant functional limitations. While surgical reconstruction offers high rates of return to competition, there are no validated or universally accepted guidelines for determining when an athlete can safely resume play. Purpose: To assess the existing scientific literature for return-to-competition criteria utilized after ulnar collateral ligament reconstruction. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: The PubMed database was searched for clinical investigations of ulnar collateral ligament reconstruction in overhead throwing athletes published between January 2000 and June 2020. Only studies that had a minimum follow-up of 1 year and included at least 1 specific return-to-competition criterion were considered. Results: A total of 15 studies were included in the final analysis, encompassing 1156 patients with an average age of 20.7 years (SD, 2.0 years). Baseball players composed 96.3% of patients for whom sport was specified, and 92.4% of baseball players were pitchers. The most common return-to-competition criterion, identified in 87% of studies, was completion of a return-to-throwing program, which started on average 16.7 weeks (range, 12-18 weeks) after surgery. A return-to-mound program was utilized in 53% of studies, starting on average 7.4 months (range, 6-9 months) postoperatively. Minimum time from surgery was used in 73% studies, with players waiting 7 to 12 months (mean, 9.7; SD, 1.4 months) after surgery before return-to-competition consideration. The overall rate of return to competition at the preinjury level or higher was 85.7% (SD, 8.5%) at an average of 12.2 months (SD, 0.6 months). Conclusion: In general, we observed a paucity of literature describing the return-to-competition process after ulnar collateral ligament reconstruction in overhead throwing athletes. Only 3 explicit return-to-competition criteria were identified across all studies: completion of a return-to-throwing program, completion of a return-to-mound program for pitchers, and minimum time from surgery. Increased transparency regarding postoperative rehabilitation protocols and further research are necessary to identify and validate sport-specific return-to-competition criteria, which will ultimately help athletes return to play in a safe and timely fashion after ulnar collateral ligament reconstruction. [ABSTRACT FROM AUTHOR]