Sectioning of the Anterior Intermeniscal Ligament Changes Knee Loading Mechanics.

PURPOSE: The purpose of this cadaver research project was to describe the biomechanical consequences of anterior intermeniscal ligament (AIML) resection on menisci function under load conditions in full extension and 60° of flexion.

METHODS

Ten unpaired fresh frozen cadaveric knees were dissected leaving the knee joint intact with its capsular and ligamentous attachments. The femur and tibia were sectioned 15 cm from the joint line and mounted onto the loading platform. A linear motion x-y table allows the tibial part of the joint to freely translate in the anterior-posterior direction. K-scan sensors were used to define contact area, contact pressure, and position of pressure center of application (PCOA). Two series of analysis were planned: before and after AIML resection, mechanical testing was performed with specimens in full extension (1,400 N load) and in 60° of flexion (700 N load) to approximate heel strike and foot impulsion during the gait.

RESULTS

Sectioning of the AIML produced mechanical variations below the 2 menisci when specimens were at full extension and loaded to 1,400 N: increasing the mean contact pressure (delta 0.4 ± 0.2 MPa, +15% variation P = .008) and maximum contact pressure (delta 1.50 ± 0.8 MPa, 15% variation P < .0001) and decreasing of tibiofemoral contact area (delta 71 ± 51 mm2, -15% variation P < .0001) and PCOA (delta 2.1 ± 0.8 mm). At 60° flexion, significant differences regarding lateral meniscus mechanical parameters were observed before and after AIML resection: mean contact pressure increasing (delta 0.06 ± 0.1 MPa, +21% variation P = .001), maximal contact-pressure increasing (delta 0.17 ± 0.9 MPa, +28% variation P = .001), mean contact area decreasing (delta 1.84 ± 8 mm2, 4% variation P = .3), and PCOA displacement to the joint center (mean displacement 0.6 ± 0.5 mm).

CONCLUSIONS

The section of the intermeniscal ligament leads to substantial changes in knee biomechanics, increasing femorotibial contact pressures, decreasing contact areas, and finally moving force center of application, which becomes more central inside the joint.

CLINICAL RELEVANCE: AIML resection performed ex vivo in this study, might potentially be deleterious in vivo. Clinical studies focusing on preserving or even repairing the AIML are needed to evaluate those ex vivo elements.