Influence of Varus Alignment on Survivorship After Lateral Meniscal Allograft Transplantation

Abstract

Background: Factors associated with graft survival after lateral meniscal allograft transplantation (MAT) have not been fully determined, and survival analysis focused on effect of varus alignment has not been performed. Hypothesis: Varus alignment of the knee leads to better graft survival and clinical outcomes after lateral MAT than normal alignment. Study Design: Cohort study; Level of evidence, 2. Methods: The records of 204 consecutive patients who underwent lateral MAT were reviewed. After exclusion of cases undergoing revision MAT, cases without hip-knee-ankle standing radiographs, and cases with valgus alignment, the patients were categorized into 2 groups, those with normal alignment within −3° to 3° of the mechanical axis and those with varus alignment >3°. Cumulative graft survival rates were compared in the 2 groups before and after controlling for other covariates, including sex, age, body mass index (BMI), time from meniscectomy, the number of accompanying procedures, and cartilage status. Failure was defined as (1) a graft tear involving >50% or unstable peripheral rim of the allograft; (2) a Lysholm score <65 that was not improved afterward; (3) meniscectomy >50% or to the zone of meniscocapsular junction; or (4) conversion to revision MAT, realignment osteotomy, or arthroplasty. Clinical outcomes were compared between the 2 groups by Lysholm score. Results: Of the 190 patients, 149 showed normal alignment of 0.3° ± 1.3° (range, –3° to 3°) and 41 showed varus alignment of 4.8° ± 0.6° (range, 4°-8°). A total of 22 patients (11.6%) experienced MAT failure: 21 patients with normal alignment and 1 with varus alignment. Kaplan-Meier survival analysis showed a significant difference in the cumulative graft survival rates between the 2 groups (log-rank test, P = .001). After controlling for age, sex, BMI, time from meniscectomy, the number of accompanying procedures, and cartilage status, varus alignment was found to be a significant protective factor (P = .004). On the other hand, there was no difference in clinical improvement measured by the Lysholm score between the 2 groups (P = .651). Conclusion: Varus alignment was associated with better graft survival after lateral MAT than normal alignment. However, no significant differences in clinical outcomes were observed.