Tibiofemoral rotation is significantly higher in patients with patellofemoral maltracking and torsional deformity

INTRODUCTION: Tibiofemoral (TF) rotation, the relative rotational alignment between femur and tibia in the axial plane at the level of the knee has been investigated as a parameter of joint alignment. Its influence on patellofemoral pathologies is largely unknown. Within this cross sectional study, it was hypothesized that TF rotation is increased in patients with symptomatic torsional femoral or tibial deformity and associated patellofemoral maltracking compared to healthy individuals. METHODS: This single-center-study included patients with patellofemoral maltracking, including patellofemoral instability, who underwent tibial and/or femoral derotational osteotomy (surgery 2019–2024) and for whom preoperative torsional MRI was available. Torsion was measured according to Waidelich et al. and TF rotation defined as the angle between a tangent on the dorsal femoral condyles and a tangent on the dorsal tibial plateau. Positive values indicating external, negative values internal rotation. Tibial-tuberosity-trochlea-groove (TT-TG) distance was measured additionally. Interrater reliability was calculated between measurements of orthopaedic surgeons and musculoskeletal radiologists. Results were compared with those of a healthy control group that had previously been published. RESULTS: 86 cases were included (age 25.0 ± 9.0, 78% females). Level of derotational osteotomy was femoral in 36% (n = 31), tibial in 26% (n = 22), double-level in 38% (n = 33). Interrater reliability was good to excellent for all parameters measured. TF rotation (5.6 ± 6.7°) was significantly increased (P < .001) compared to healthy subjects (1.3 ± 3.9°). 50% of the cases suffered from patellofemoral instability. Among these, TF rotation was significantly increased compared to cases without instability (7.5 ± 7.3° vs. 3.8 ± 5.5°; P = .011). TF rotation correlated moderately negative with tibial torsion (rs=-0.284; P = .008) and moderately positively with TT-TG-distance (rs=0.487, P < .001). There was no significant difference in TF rotation between different osteotomy levels. CONCLUSION: TF rotation is significantly increased in patients with symptomatic torsional deformity and associated patellofemoral maltracking and should therefore be included in future investigations for establishing further treatment recommendations.