Meniscal deficiency after discoid lateral meniscus resection often leads to early lateral compartment degeneration. Clarifying the impact of lateral femoral condyle (LFC) squaring on graft behavior and outcomes may help optimize lateral meniscal allograft transplantation (MAT) results.

This study aimed to compare LFC morphology, specifically the presence of condylar squaring, with meniscal graft extrusion, radiological structural characteristics, and clinical outcomes following lateral MAT.

A total of 108 patients undergoing lateral MAT were retrospectively divided into two groups based on LFC squaring: Group S (n = 57) and Group N (n = 51). Comparisons included radiographic indices, MRI-based graft extrusion, graft signal intensity, and cartilage status graded by the International Cartilage Repair Society (ICRS) system, SPECT/CT subchondral metabolic activity, and clinical outcome scores at pre- and postoperative follow-up. All surgeries followed a uniform technique and rehabilitation protocol, with blinded radiologic assessments.

Group S demonstrated narrower lateral-edge joint-space width both preoperatively (3.5 ± 1.7 mm vs 4.2 ± 1.5 mm; p = 0.004) and at final follow-up (4.1 ± 1.9 mm vs 4.9 ± 1.7 mm; p = 0.023). High-grade cartilage lesions (ICRS ≥ 3) were more frequent in Group S before surgery (33.3% vs 11.8%; p = 0.008). At 1 year, graft extrusion was greater in Group S (3.5 ± 0.8 mm vs 2.2 ± 0.6 mm; p < 0.001), with a higher proportion of extrusion ≥3 mm (40.4% vs 7.8%; p < 0.001). Group S showed a significantly larger increase in coronal extrusion (2.6 ± 0.9 mm vs 1.2 ± 0.7 mm; p < 0.001). Graft signal intensity did not differ between groups. In the SPECT/CT subgroup, SUVmax at LFC was higher in Group S (7.8 ± 5.8 vs 4.3 ± 3.1; p = 0.012). At ≥2-year follow-up, Lysholm and IKDC scores and isokinetic extensor strength recovery showed no significant between-group differences.

In this observational study, LFC squaring was associated with narrower lateral joint-space width and greater meniscal graft extrusion after lateral MAT. Despite these structural differences, short-term patient-reported outcomes and muscle strength recovery did not differ between groups. These findings suggest that while LFC squaring reflects a less favorable biomechanical environment, its clinical significance requires further evaluation in longer-term follow-up studies.

III; retrospective comparative study