Kinematic variation and pain in dynamic knee collapse
Dynamic knee collapse is often cited as one of the primary contributors to the development of patellofemoral pain (PFP). Altered hip and knee mechanics theoretically increases the stress on the patellofemoral joint by decreasing the magnitude of the contact surface of the patella during motion. Previous research has shown that when instructed to correct, patients with PFP were able to alter hip and knee segments however little to no information is available regarding the pelvis, femur, and tibia to hip and knee mechanics. Considering this, the authors of the present study sought to determine any kinematic differences before and after corrective instruction of dynamic knee collapse in patients with PFP as well as if there was a pain reduction associated with improved segment kinematics. It was shown that after instruction there was decreased adduction at both the pelvis and the femur and that pain levels were associated with kinematics moving in the direction opposite to the dynamic knee collapse.
Twenty females with chronic PFP between the ages 18 and 40 years old were included in the study. Kinematic data was collected utilizing an eight camera three-dimensional motion capture system. Patients were asked to perform a single-leg squat following demonstration and again following corrective instruction. Three trials of each movement condition were recorded and patients completed a visual analog scale following each condition.
The current study was undertaken in order to further expand our knowledge base regarding the etiology of patellofemoral pain. After instruction it was shown that subjects had increased lateral pelvic and trunk flexion toward the affected side. Furthermore it was shown that subjects also had a decrease in femoral and tibial internal rotation as well as femoral adduction. From this, it was then shown that a decrease in femoral internal rotation and greater trunk lateral flexion toward the weight bearing sided were associated with lower VAS scores.
With the expanding complexity of knowledge regarding PFP, what should we address first as clinicians to improve our patient outcomes?
> From: Graci, J Sci Med Sport (2015) 5(Epub ahead of print). All rights reserved to Elsevier Ltd.. Click here for the Pubmed summary.