Arthroscopy - 2026-04-23 - Journal Article
Lateral Meniscus Posterior Root Repair with Lateral Extra-articular Tenodesis Significantly Decreased Internal Rotation and Pivot Shift Loading in a Cadaveric Study of Anterior Cruciate Ligament Reconstructed Knees.
van der Wal WA, Tollefson LV, Hoogeslag RAG, Slette EL, Carlson MR, Shoemaker EP, LaPrade RF
Topics
Key Takeaway
In ACL-reconstructed cadaveric knees with concurrent lateral meniscus posterior root (LMPR) and Kaplan fiber injuries, adding a modified Lemaire lateral extra-articular tenodesis restored pivot-shift and internal rotation stability to intact-knee levels (all P > .086), while LMPR repair alone most effectively restored coupled valgus rotation during pivot shift.
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Summary
This study used a 6-DOF robotic system on 10 paired cadaveric knees to quantify the individual and combined biomechanical contributions of LMPR tears, Kaplan fiber tears, ACLR, LMPR repair, and modified Lemaire LET under internal rotation torque and simulated pivot-shift loading. ACLR alone left significant residual internal rotation (15°–90°, P < .001), coupled anterior tibial translation (0°–45°, P < .05), and coupled valgus rotation (15°–90°, P < .003). Adding Lemaire LET to ACLR—with or without LMPR repair—restored isolated IR, coupled IR, and coupled ATT to intact levels, while LMPR repair contributed most to restoring coupled valgus rotation during pivot shift.
Key Limitation
The small sample of 10 cadaveric knees limits statistical power to detect differences between reconstruction states, and cadaveric tissue quality variability (age, bone density, soft-tissue integrity) may not represent the young athletic population most likely to sustain these combined injuries.
Original Abstract
PURPOSE
To determine the biomechanical effects of lateral meniscus posterior root- (LMPR) and Kaplan fiber tears in anterior cruciate ligament-(ACL) deficient knees and assess the impact of LMPR repair, modified Lemaire lateral extra-articular tenodesis, or both, after ACL reconstruction (ACLR).
METHODS
Ten paired cadaveric knees were randomized into four groups and mounted in a six degrees of freedom robotic system. The ACL, LMPR, and Kaplan fibers were sequentially sectioned in random order. After ACLR, LMPR repair and Lemaire were performed in random order. Tibial displacements and rotations were measured under internal rotation (IR) torque and a simulated pivot shift at 0°-90° knee flexion.
RESULTS
ACLR alone did not fully restore stability, with significant residual increases in isolated IR between 15° and 90° (all P < .001), coupled IR at all flexion angles (all P < .01), coupled anterior tibial translation (ATT) between 0° and 45° (all P < .05), and coupled valgus rotation between 15° and 90° (all P < .003) during pivot shift. Adding Lemaire to ACLR, without or with LMPR repair, restored stability comparable to the intact knee for isolated IR (without, all P > .086; with, all P > .132), coupled IR (without, all P > .102; with, all P > .172), and coupled ATT (without, all P > .537; with, P > .872) during pivot shift. LMPR repair in ACLR with Kaplan fiber injury restored valgus rotation stability at most flexion angles (all P > .053).
CONCLUSIONS
Both the LMPR and Kaplan fibers act as secondary stabilizers to IR and pivot shift loading in the ACL deficient knee, with an additive biomechanical effect of the Kaplan fibers to the ACL with LMPR deficient knee for isolated IR and for coupled IR and ATT during pivot shift. Furthermore, the most important reconstruction state which best restored stability comparable to the ACL intact state was the addition of lateral extra-articular tenodesis to either the ACLR alone or ACLR with LMPR repair state, except for valgus rotation during pivot shift, where LMPR repair contributes most.
CLINICAL RELEVANCE
Both LMPR repair and anterolateral corner reconstruction are necessary to restore stability in knees with ACL, Kaplan fiber, and LMPR injuries.