Effect of sagittal allograft position on coronal extrusion in lateral meniscus allograft transplantation.

Purpose: This study assessed the incidence of graft extrusion on the sagittal plane on magnetic resonance imaging (MRI) and evaluated the correlation between the sagittal position of the allograft and coronal graft extrusion.

Methods: The study involved 99 patients who underwent lateral meniscus allograft transplantation (LMAT) for knees that had undergone total meniscectomy and 50 sex- and age-matched control patients who underwent MRI for evaluation of knee pain and had no intra-articular lesions. Graft extrusion and sagittal graft position parameters, including the distance from the articular cartilage center to the anterior meniscus (CAMD), the distance from the articular cartilage center to the posterior meniscus, the distance from the anterior articular cartilage margin to the anterior horn (ACMD), or the distance from the posterior articular cartilage margin to the posterior horn, were assessed on immediate postoperative MRI studies (2 days after surgery) and compared between the LMAT and control groups. In the LMAT group, correlations between graft extrusion and MRI parameters were analyzed, and multiple linear regression analysis was performed to identify predictors of graft extrusion.

Results: The mean CAMD and mean ACMD were significantly greater and the mean distance from the articular cartilage center to the posterior meniscus and the mean distance from the posterior articular cartilage margin to the posterior horn were significantly smaller in the LMAT group than in the normal control group (P < .001 for each). CAMD (r = 0.294, P = .015) and ACMD (r = 0.244, P = .041) correlated with relative extrusion, and CAMD (r = 0.288, P = .013) correlated with absolute extrusion. CAMD was the only predictor independently associated with both absolute (β = 0.248, P = .013) and relative (β = 0.244, P = .015) extrusion.

Conclusions: Transplanted lateral meniscal allografts were located more anteriorly on the sagittal plane than normal lateral menisci. More anterior allograft placement correlated with a greater degree of graft extrusion on the coronal plane.

Level Of Evidence: Level III, retrospective case-control study.