Increased posterior tibial slope is associated with decreased short- and mid-term survivorship after meniscal allograft transplantation

Evaluate the association between posterior tibial slope and survivorship following meniscal allograft transplantation and to determine whether a slope threshold is associated with increased risk of graft failure at short-term follow-up. A retrospective cohort study was performed of patients who underwent meniscal allograft transplantation from 2011 to 2024 with postoperative lateral radiographs and a minimum 1-year follow-up. Posterior tibial slope was measured using the circle-of-best-fit method. Graft failure was defined as revision surgery, conversion to arthroplasty and meniscal repair and/or meniscectomy of the allograft. Multivariable logistic regression and Cox proportional hazards modelling were used to evaluate the association between slope and failure. Receiver operating characteristic analysis with Youden's index was used to identify an optimal posterior tibial slope threshold, and Kaplan-Meier analysis assessed graft survivorship. Eighty-three meniscal allograft transplantations were included (age 30.7&#x2009;&#xb1;&#x2009;8.6 years, 55.4% male) with a mean follow-up of 4.4&#x2009;&#xb1;&#x2009;3.1 years. Twenty-four clinical graft failures (28.9%) occurred at a mean time of 2.3&#x2009;&#xb1;&#x2009;1.9 years postoperatively. Mean posterior tibial slope was 11.3&#xb0;&#x2009;&#xb1;&#x2009;3.0&#xb0; and was not significantly associated with failure when analyzed as a continuous variable (OR 1.1, 95% CI 1.0-1.4, p&#x2009;=&#x2009;0.174). Receiver operating characteristic analysis identified a threshold of 11.9&#xb0;, above which survivorship was reduced. Kaplan-Meier analysis demonstrated decreased survival for slope &#x2265;11.9&#xb0; (log-rank p&#x2009;<&#x2009;0.001). Compartment-specific analyses demonstrated similar patterns. Although posterior tibial slope was not independently associated with graft failure when modelled continuously, a threshold of approximately 11.9&#xb0; was associated with reduced meniscal allograft transplantation survivorship. These findings suggest a potential threshold-dependent relationship between sagittal alignment and graft survival. Level III.