Impact of Surgery on Patellar Bone Strain in Patients with Crouch Gait

Crouch gait, characterized by excessive hip and knee flexion with exaggerated dorsiflexion during stance-phase of gait, results in unusually high stresses at the patellofemoral (PF) joint. Tibial tubercle osteotomy, patellar tendon partial resection, and patellar tendon imbrication are three commonly used surgical techniques aimed to restore normal knee mechanics. Quantifying bone strain in the patella through patient-specific finite element (FE) computational models can serve as an indicator to determine which surgical technique can best alleviate anterior knee pain as a surgical complication. Patient-specific FE models are created from reconstructions of magnetic resonance (MR) and computerized tomography (CT) scans. Experimental kinematic gait and ground reaction force data, collected using a marker-based motion capture system, are incorporated into a rigid-body musculoskeletal model (OpenSim, Standford, CA) to predict pre- and post-operative muscle forces for twelve subjects. To evaluate the effect of surgery on knee mechanics the maximum and minimum principal strains extracted from a detailed, dynamic FE model are compared for each individual. This type of analysis can aid a clinician in determining the optimal surgical intervention to prevent early onset patellofemoral osteoarthritis on a case-by-case basis