Tear patterns and locations are different between lateral and medial compartments in patients with early anatomical failure after meniscal allograft transplantation.

PURPOSE: To investigate the characteristics of anatomically failed grafts within 1 year after meniscal allograft transplantation (MAT) and compare the differences between lateral and medial MATs. METHODS: The records of consecutive patients with anatomically failed grafts within 1 year after primary MAT between 2005 and 2018 were reviewed. Anatomical failure was defined as a tear covering > 50% of the allograft or an unstable peripheral rim. The pattern and location of the graft tears were analyzed using magnetic resonance imaging or arthroscopy. RESULTS: A total of 21 patients were included. All 21 patients had anatomical failure with tears involving > 50% of the allograft, whereas 15 had an unstable peripheral rim of the allograft. The mean failure time was 6.6 ± 3.6 months in all patients (lateral MAT, n = 15; medial MAT, n = 6). In the lateral MAT group, meniscocapsular separation was the most common pattern (n = 10, 66.7%), followed by complex (n = 3, 20.0%), radial (n = 1, 6.7%), and longitudinal (n = 1, 6.7%) tear. In the medial MAT group, a root tear was the most common pattern (n = 5, 83.3%), followed by a complex tear (n = 1, 16.7%). Meanwhile, in the lateral MAT, the midbody was the most frequently affected location (n = 9, 60.0%), followed by the posterior (n = 5, 33.3%) and anterior (n = 1, 6.7%) areas; in the medial MAT group, the posterior (n = 5, 83.3%) was the most frequently affected location, followed by the anterior area (n = 1, 16.7%). Significant differences in the pattern (P = 0.002) and location (P = 0.043) of the graft tears were found between lateral and medial MATs. CONCLUSION: In patients with early failure after MAT, meniscocapsular separation in the midbody of the lateral compartment and root tears in the posterior area of the medial compartment were the most common. Thus, surgeons are encouraged to pay extra attention to these vulnerable areas during the early period after MAT. LEVEL OF EVIDENCE: IV.