Cadaveric biomechanical study from HSS testing how medial meniscectomy affects anterior-posterior tibial displacement and coupled rotation. Four conditions were compared: intact, meniscectomy alone, ACL sectioning alone, and combined meniscectomy plus ACL sectioning. Testing was performed at 0°, 30°, 60°, and 90° of knee flexion using a dynamic servohydraulic apparatus.
Meniscectomy in an ACL-intact knee does not worsen anterior instability — this paper gives you the biomechanical basis to reassure a patient with an isolated meniscal tear that meniscectomy alone will not destabilize the joint.
The calculus changes completely once the ACL is gone. When you are operating on an ACL-deficient knee and encounter a torn medial meniscus, removing it compounds the instability by up to 58% at 90° of flexion. Preserve every millimeter of posterior horn tissue you can.
This paper is also the mechanical explanation for a pattern you will see clinically: patients with chronic ACL deficiency disproportionately develop medial meniscal tears. The posterior horn is chronically overloaded acting as a secondary stabilizer, and eventually it fails.
For boards: the medial meniscus is a secondary stabilizer to anterior tibial translation only in the ACL-deficient state, acting via posterior horn wedging. Not in the ACL-intact knee.
Cadaveric biomechanical study from HSS testing how medial meniscectomy affects anterior-posterior tibial displacement and coupled rotation. Four conditions were compared: intact, meniscectomy alone, ACL sectioning alone, and combined meniscectomy plus ACL sectioning. Testing was performed at 0°, 30°, 60°, and 90° of knee flexion using a dynamic servohydraulic apparatus.
Meniscectomy in an ACL-intact knee does not worsen anterior instability — this paper gives you the biomechanical basis to reassure a patient with an isolated meniscal tear that meniscectomy alone will not destabilize the joint.
The calculus changes completely once the ACL is gone. When you are operating on an ACL-deficient knee and encounter a torn medial meniscus, removing it compounds the instability by up to 58% at 90° of flexion. Preserve every millimeter of posterior horn tissue you can.
This paper is also the mechanical explanation for a pattern you will see clinically: patients with chronic ACL deficiency disproportionately develop medial meniscal tears. The posterior horn is chronically overloaded acting as a secondary stabilizer, and eventually it fails.
For boards: the medial meniscus is a secondary stabilizer to anterior tibial translation only in the ACL-deficient state, acting via posterior horn wedging. Not in the ACL-intact knee.