Proximal Tibiofibular Joint Inclination Angle is not Associated With Lateral Meniscal Tears
G.G. Ribeiro, L.N.F. De Lima, M. Cohen, N.G. Oliveira Filho, L.S.A. Oliveira, V.A. MachadoPurpose.
To determine whether proximal tibiofibular joint (PTFJ) inclination differs between adults with an isolated lateral meniscal tear and controls without intra-articular knee pathology, and to assess agreement between the classic PTFJ angle and a plateau-referenced alternative.
Methods.
Single-center retrospective case-control study of 33 adults (18–49 years) with an isolated lateral meniscal tear and 44 frequency-matched controls, selected from 1,533 clinically indicated knee MRI examinations; discoid lateral meniscus was excluded. Two blinded radiologists independently measured both angles on the sagittal section through the largest dimension of the joint. Co-primary endpoints were the between-group mean differences (Bonferroni-protected α = 0.05).
Results.
The classic angle was 31.2° ± 6.6° in cases versus 29.7° ± 6.8° in controls (mean difference 1.50°, 95% CI −1.58 to 4.58; p = 0.335), and the alternative angle 39.1° ± 6.8° versus 38.6° ± 6.0° (mean difference 0.55°, 95% CI −2.35 to 3.44; p = 0.708). Adjustment for age and sex did not change these results. Inter-reader agreement was good (intraclass correlation 0.84 and 0.88). The two methods correlated moderately (r = 0.66; p < 0.001) but differed by a systematic 8.5° offset.
Conclusions.
In adults without discoid lateral meniscus, PTFJ inclination did not differ between knees with and without an isolated lateral meniscal tear. The proposed alternative is not a numerically equivalent substitute for the classic angle. Routine measurement is unlikely to help discriminate isolated lateral meniscal tears in this population.