Computed Tomography Imaging Analysis of the MPFL Femoral Footprint Morphology and the Saddle Sulcus: Evaluation of 1094 Knees

Abstract

Background: The medial patellofemoral ligament (MPFL) has been reported to be anatomically attached from an osseous saddle region (saddle sulcus) between neighboring landmarks on the femur, including the adductor tubercle (AT), medial epicondyle (ME), and medial gastrocnemius tubercle (MGT). However, the position and prevalence of the saddle sulcus remain unknown. Purpose: To study the femoral footprint of MPFL and the prevalence of the saddle sulcus with computed tomography (CT) imaging; quantify the position of the saddle sulcus; and determine the relevant factors of the identified position and measuring distances. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 1094 knees in 753 patients were studied. Knees were organized into an anterior cruciate ligament reconstruction (ACLR) group (controls) and a recurrent patellar dislocation (RPD) group. Using 3-dimensionally reconstructed CT images, the authors determined the prevalence of the saddle sulcus and its position relative to the AT, the ME, the Schöttle point (1.3 mm anterior to the distal posterior cortex and 2.5 mm distal to the posterior origin of the medial femoral condyle), and the Fujino point (approximately 10 mm distal to the AT). Analysis of covariance was used to adjust for age, sex, side, and body mass index on the measurements. Results: There were 555 knees in the control group and 539 knees in the RPD group. The MPFL femoral footprint presented as an oblique, oblong, osseous region (saddle sulcus) in 75.7% of knees (75.0%, ACLR group vs 76.4%, RPD group; P