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

Purpose 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. Methods 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. Results Forty‐one LMPR repairs and 20 matched controls were included. Pre‐operative instability was similar between groups (pivot shift p = 0.09, KT‐1000 p = 0.92). Significant improvements in pivot shift and KT‐1000 were observed post‐operatively in both groups (all p < 0.001), with no post‐operative differences between them (pivot shift p = 0.72, KT‐1000 p = 0.94). PROMs improved significantly in all groups ( p < 0.001) with no post‐operative group differences. Post‐operative reduction of LME did not differ statistically among tear types ( p > 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 ( p = 0.46). The presence of LFNS or pMFL was not associated with tear type or with LMPR versus control status ( p > 0.05). Conclusion 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 of Evidence Level III, retrospective comparative study.