Lateral meniscus posterior root repair during ACL reconstruction restores knee stability and results in outcomes comparable to isolated ACL reconstruction: A propensity-matched cohort analysis.

Abstract

To compare clinical and MRI outcomes as well as knee anterior-posterior (AP) and rotational stability between ACL reconstructions (ACLR) with concomitant lateral meniscus posterior root (LMPR) repair and matched isolated ACLR, while assessing whether different LMPR tear patterns affect post-operative stability, healing or meniscal extrusion. A retrospective review was performed on patients < 55 years old who underwent ACLR and LMPR repair between 2018 and 2022, with minimum 2-year follow-up. Patients with osteoarthritis, prior meniscal or cartilage surgery, revision ACLR, or multi-ligament injuries were excluded. The LMPR group was stratified into oblique radial (I), longitudinal/T-type (II), and avulsion (III) tears. A 2:1 propensity score-matched control cohort of isolated ACLR was created. Pre- and post-operative knee stability (pivot shift, KT-1000), PROMs (IKDC, Lysholm, Tegner), LMPR healing, lateral meniscus extrusion (LME), and MRI parameters (posterior meniscofemoral ligament) pMFL, (lateral femoral notch sign) LFNS were analysed. Forty-one LMPR repairs and 20 matched controls were included. Pre-operative instability was similar between groups (pivot shift <i>p</i> = 0.09, KT-1000 <i>p</i> = 0.92). Significant improvements in pivot shift and KT-1000 were observed post-operatively in both groups (all <i>p</i> < 0.001), with no post-operative differences between them (pivot shift <i>p</i> = 0.72, KT-1000 <i>p</i> = 0.94). PROMs improved significantly in all groups (<i>p</i> < 0.001) with no post-operative group differences. Post-operative reduction of LME did not differ statistically among tear types (<i>p</i> > 0.05), but LME still remained slightly higher in the study group. LMPR healing was high (75.6% complete, 24.4% partial) with no failures and no difference in healing across tear patterns (<i>p</i> = 0.46). The presence of LFNS or pMFL was not associated with tear type or with LMPR versus control status (<i>p</i> > 0.05). LMPR repair performed during ACLR successfully restores knee stability, decreases LME, and achieves functional outcomes similar to isolated ACLR. Tear morphology does not significantly affect post-operative clinical or magnetic resonance imaging results. Level III, retrospective comparative study.