All-Inside Suture Fixation of the Lateral Meniscus to the Popliteal Tendon: A Biomechanical Evaluation.

Background: Lesions of the posterolateral parts of the lateral meniscus are commonly treated with all-inside suture repair. The popliteal tendon is one of the few anatomic structures available to attach these anchor systems. However, this method is controversial and its biomechanical effects are unknown.

Hypothesis: Suture fixation of the lateral meniscus to the popliteal tendon significantly affects the mobility of both structures involved.

Study Design: Descriptive laboratory study.

Methods: Six fresh-frozen human knee specimens were tested using a biaxial servohydraulic testing machine. Ten loading cycles of ±10° internal-external rotation were performed under 100 N axial load and 30° joint flexion. The popliteal muscle was constantly loaded with 44 N. A 3-dimensional optical measurement system recorded the movement of the lateral meniscus, popliteal tendon, and lateral femoral condyle. The resultant torque was also measured. Each knee joint was tested without and with suture fixation of the lateral meniscus to the popliteal tendon. All-inside suture repairs were performed under arthroscopic control.

Results: Fixation of the lateral meniscus to the popliteal tendon resulted in a significant reduction in both (absolute and relative) movement of the components involved. On average, the absolute displacement of the lateral meniscus decreased by 34.3% (1.2 mm; < .001) and that of the popliteal tendon proximal to the suture by 18.8% (0.3 mm; = .02). There was a 23.5% (0.8 mm; < .001) reduction in relative movement between the lateral femoral condyle and lateral meniscus, a 17.1% (0.6 mm; = .004) reduction between the lateral femoral condyle and popliteal tendon distal to the suture, and a 25.0% (0.7 mm; < .001) reduction between the lateral meniscus and popliteal tendon proximal to the suture. Regarding the measured torque, a significant reduction of 2.0 Nm (18.2%; = .04) was measured for femoral internal rotation.

Conclusion: All-inside suture fixation of the lateral meniscus to the popliteal tendon shows significant biomechanical effects.

Clinical Relevance: Our results suggest increased tension on the suture with possible implications for meniscal healing. These findings may require adaptation of postoperative management, considering more restrictive treatments or resorbable suture anchors.