Lateral meniscus posterior root repair in the setting of anterior cruciate ligament reconstruction restores joint mechanics to the intact state and improves clinical function: a systematic review of biomechanical and clinical outcomes

Purpose: To perform a systematic review of biomechanical and clinical outcomes following lateral meniscus posterior root (LMPR) repair with concomitant anterior cruciate ligament reconstruction (ACLR). Methods: A literature search was performed systematically using PubMed, Embase, and Medline databases in April 2022. The search included the following terms combined with Boolean operators: ‘Meniscus repairs’, ‘Meniscal Repair’, ‘Posterior Horn’, ‘Root’, ‘Radial’. Inclusion criteria consisted of level I-IV human clinical and biomechanical studies reporting biomechanical data and/or outcomes following LMPR repair in the setting of ACLR. Results: Three biomechanical studies, all utilizing a transtibial pullout technique, were identified, all of which reported significant improvement in joint contact pressures and mechanics and 3/4 of which reported significant improvement in anterior or rotational stability with LMPR repair. Five clinical studies, consisting of 146 patients (mean age 28.5 ± 1.1 years) undergoing LMPR repair, were identified with an average follow-up of 19.1 months (range 6.2–46 months). Across all clinical studies, Lysholm and International Knee Documentation Committee (IKDC) scores were found to improve postoperatively, with 3/4 reporting significant improvement in Lysholm (all, p ≤ 0.001) scores and 3/5 reporting significant improvement in IKDC scores when compared to preoperative values (all, p ≥ 0.004). Meniscal extrusion decreased significantly following repair in 2/4 studies (all, p ≤ 0.001). Conclusions: Biomechanically, transtibial pullout repair of the LMPR restored joint contact pressures and joint mechanics to intact levels when performed with concomitant ACLR. Clinically, LMPR repair with concurrent ACLR resulted in improved Lysholm and IKDC scores. These findings enable surgeons to determine optimal treatment plans and discuss realistic outcomes with patients when encountering LMPR injuries. Level of evidence: IV.