Impact of Medial Meniscotibial Ligament Disruption Compared to Peripheral Medial Meniscal Tear on Knee Biomechanics.

Medial meniscotibial ligament (MTL) lesions may go unrecognized and untreated and have detrimental impact on knee biomechanics and joint pathology. Therefore, this study was designed to compare the biomechanical impact of midbody MTL disruption to corresponding peripheral medial meniscal (PMM) tears in anterior cruciate ligament (ACL) intact and ACL-deficient cadaveric knees. Cadaveric knees (n = 12; 6 matched pairs) were tested for laxity and ACL strain under anterior, valgus, and external rotation loading at 0, 30, and 90 degree of flexion. Knees were randomly assigned to ACL-intact (n = 6) or ACL-deficient (n = 6) groups. Large midbody MTL disruption or corresponding PMM tears were created (n = 3/group) and knees retested. PMM tears were repaired arthroscopically with inside-out suturing, and MTL lesions were repaired with suture anchors via an open approach. Knees were retested after repair. Biomechanical testing data were compared for statistically significant differences. Large MTL and PMM lesions were associated with significant increases in ACL strain, anterior laxity at 0, 30, and 90 degrees (p = 0.006), valgus laxity (p = 0.0012), and external rotation laxity (p = 0.0003) compared with intact knees. Repair of each lesion restored knee stability and reduced ACL strain to intact levels. In ACL-deficient knees, there was significantly increased anterior, valgus, and external rotation laxity compared with the ACL-intact state and MTL and PMM lesions further increased laxity at all angles. However, differences were not statistically significant and repair of meniscal lesions alone did not restore stability to ACL-deficient knees. These results highlight the need to recognize medial MTL injury and perform an appropriate repair procedure to restore knee stability and protect against excessive ACL strain.

Optimizing Patellofemoral Cartilage Restoration and Instability With Tibial Tubercle Osteotomy.

Tibial tubercle osteotomy (TTO) is a procedure that may be used to address a wide array of patellofemoral joint pathology. The most common indications for TTO include (1) patellar instability, including either a lateralized force vector or abnormal patellar alta, and (2) patellar focal cartilage defects or chondromalacia. Customization of the TTO can effectively address the patellofemoral joint pathology by modifying patellar tracking in the trochlear groove and/or altering the contact pressures experienced by the patellofemoral cartilage. TTO may be most successful when performed in conjunction with soft-tissue stabilization and/or biological augmentation of chondral injuries. Specifically, isolated anteromedialization is recommended for focal, distal lateral patellar lesions; combined anteromedialization and cartilage restoration are recommended for medial, central, and/or panpatellar cartilage pathology; medialization with soft-tissue stabilization is recommended for a lateralized tubercle position (elevated tibial tubercle-trochlear groove distance); and distalization with soft-tissue stabilization is recommended for patella alta. Clinical studies have shown good to excellent results at long-term follow-up when a TTO is performed for patellar instability, whereas TTO performed for chondral defects has shown good to excellent outcomes that correlate strongly with the size and location of the chondral defect. With appropriate patient selection, TTO is a valuable tool for the treatment of patellofemoral joint pathology.