Assessment of Femoral Version Should be Assessed Independently of Conventional Measures in Patellofemoral Instability.

Background: The purpose of the present study is to determine the association between femoral version and traditional pathologic bony factors commonly used to measure and define patellofemoral alignment.

Methods: We performed a retrospective review of patients treated for patellofemoral instability (PFI) at a single institution. Patients included underwent magnetic resonance imaging (MRI) of the lower extremity using a rotational protocol prior to medial patellofemoral ligament reconstruction with or without tibial tubercle osteotomy. Those with a history of ipsilateral lower extremity surgery were excluded. Two independent reviewers measured femoral version, tibial tubercle-trochlear groove (TT-TG) distance, tibial tubercle-posterior cruciate ligament (TT-PCL) distance, and tibial torsion (TT). Pearson correlation coefficients were used to describe the relationships between all radiographic measures.

Results: A total of 51 knees (43 patients) were included. The average age and body mass index were 23.7 9.33 years and 29.23 8.04 kg/ m2, respectively. The mean femoral version was 15.61 11.57°. The degree of femoral version did not significantly correlate with TT-TG (r=0.103, p=0.474), TT-PCL (-0.086, p=0.550), or TT (r=0.111, p=0.438). Increased TT-TG distance was strongly associated with increased TT-PCL (r=0.470, p=0.001). In females, increased femoral version significantly correlated with increased TT (r=0.381, p=0.029).

Conclusion: Neither increased nor decreased amounts of femoral anteversion significantly correlated with TT-TG, TT-PCL, or TT. Therefore, assessment of femoral version should be measured independently of conventional measures when considering osteotomies to correct PFI. IV.