Accurate placement of a tibial tunnel significantly improves meniscal healing and clinical outcomes at 1 year after medial meniscus posterior root repair

Purpose: A medial meniscus posterior root tear results in the loss of meniscal circumferential hoop stress and causes a pathological posteromedial extrusion of the medial meniscus. Although creating a tibial tunnel in the anatomic place improves postoperative medial meniscus posterior extrusion, no studies have evaluated the relationship between tibial tunnel position and clinical outcomes. This study aimed to evaluate how tibial tunnel positioning of medial meniscus posterior root pullout repair affects meniscal healing status and clinical outcomes. Methods: Sixty-two patients with 64 medial meniscus posterior root tears (mean age 62.8 ± 7.9 years) who had undergone pullout repairs and second-look arthroscopies were included. All 62 patients were Lachman test negative. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid to assess the tibial tunnel centre and medial meniscus posterior root attachment centre. Spearman’s rank correlation analysis was undertaken to determine displacement distance from the medial meniscus posterior root attachment centre to the tibial tunnel centre and a meniscal healing score, as well as clinical outcomes at 1 year post-repair. Results: Tibial tunnel centres were located more anteriorly and medially than the medial meniscus posterior root attachment centre (mean distance 5.0 ± 2.2 mm). The mean meniscal healing score was 6.7 ± 1.8 of 10 possible points. The 1-year postoperative clinical scores showed significant improvement compared with preoperative scores for all the items. There was a significant negative correlation in the absolute distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre with the meniscal healing score (ρ = − 0.39, p = 0.002). Furthermore, there were significant positive correlations between the distance between the medial meniscus posterior root attachment centre and the tibial tunnel centre in the mediolateral direction and patient-based clinical outcomes (ρ = 0.25–0.43, p < 0.05). Conclusion: Accurate placement of a tibial tunnel, especially in the mediolateral direction, significantly improved meniscal healing and clinical outcomes at 1 year following medial meniscus posterior root repair. Surgeons should create a medial meniscus posterior root tibial tunnel at the anatomic attachment with particular attention to the mediolateral position. Level of evidence: Level IV.