Alignment differs between patellofemoral osteoarthritis cases and matched controls: An upright 3D MRI study

Area of Science:

• Orthopedics
• Biomedical Engineering
• Radiology

Background:

• Patellofemoral (PF) osteoarthritis is a common knee issue.
• Knee malalignment is a potential risk factor for PF osteoarthritis.
• Limited data exists on knee alignment in PF OA during weight-bearing activities.

Purpose of the Study:

• To evaluate three-dimensional (3D) knee alignment in individuals with PF osteoarthritis (PF OA) compared to asymptomatic controls.
• To assess alignment differences in upright, weight-bearing positions.

Main Methods:

• Utilized a vertically-oriented open-bore MRI scanner to image knees of 15 PF OA patients and 15 matched controls.
• Acquired images in two-legged stance at various knee flexion angles (0-45°) and one-legged stance at 30° flexion.
• Calculated 3D patellofemoral and tibiofemoral alignment using mixed-effects models.

Main Results:

• Four out of five measured patellofemoral alignment parameters differed significantly between PF OA cases and controls.
• PF OA patients exhibited greater lateral patellar tilt (6.6°), lateral translation (2.4 mm), and proximal translation (≥3.7 mm) compared to controls.
• No significant alignment differences were observed between two-legged and one-legged stances within either group.

Conclusions:

• Significant and clinically relevant malalignment differences exist in PF OA patients during upright weight-bearing.
• Findings support the clinical utility of current methods for identifying individuals who may benefit from malalignment correction interventions.