Individuals with patellofemoral pain syndrome have altered inter-leg force coordination

• Published in: Gait & posture 2020-06, Vol.79, p.65-70
• Main Authors: Liew, Bernard X.W., Abichandani, Deepa, De Nunzio, Alessandro Marco
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Bayes Theorem; Biomechanical Phenomena; Biomechanics; Case-Control Studies; Coordination; Female; Humans; Leg - physiopathology; Male; Middle Aged; Motor control; Movement; Patellofemoral pain syndrome; Patellofemoral Pain Syndrome - physiopathology; Spring-mass; Uncontrolled manifold; Young Adult
• ISSN: 0966-6362; 1879-2219
• DOI: 10.1016/j.gaitpost.2020.04.006

•Patellofemoral pain syndrome (PFPS) is a common overuse leg injury.•Greater inter-leg motor abundance may encourage greater inter-leg force sharing.•PFPS impairs inter-leg motor abundance during bilateral hopping.•Motor deficits occur during periods of shock absorption and peak bodyweight support.•Impaired inter-leg force sharing may prolong pain in individuals with PFPS. Patellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal disorders. Pain may be further exacerbated by atypical motor coordination strategies. It has been thought that low coordination variability may concentrate loads onto painful knee tissues. To investigate if inter-limb force coordination is altered between individuals with and without PFPS. 31 individuals (control = 17, PFPS = 14) performed bilateral vertical hopping, on two force plates at three frequencies (2.2, 2.6, 3.0 Hz). Uncontrolled manifold analysis (UCM) was used to provide an index of motor abundance (IMA) in the coordination of inter-limb forces to stabilize the two-limb’s total force. UCM was applied to the study of forces in each plane (medial-lateral (ML), anterior-posterior (AP), vertical). Bayesian Functional Data Analysis was used for statistical inference. We calculated the mean (u) with 95 % credible interval (CrI) of the difference ΔIMAcon>PFPS between the two groups. We also calculated the probability P ΔIMAcon>PFPS>0data). Individuals with PFPS had the greatest significant decrement from controls at 6% of stance hopping at 2.6 Hz by a mean difference of -0.23 for ML GRF; at 19 % of stance hopping at 2.2 Hz by a mean difference of -0.14 for AP GRF; and 52 % of stance hopping at 2.6 Hz by a mean difference of -0.14 for vertical GRF. For vertical GRF, there was a > 0.95 probability that controls had greater IMA than individuals with PFPS hopping between 12–13% of stance at 2.2 Hz, and between 48–55% at 2.6 Hz. Individuals with PFPS have reduced inter-leg force coordination for impact force attenuation and body support, compared to asymptomatic controls. The present study provides insights into a plausible mechanism underpinning persistent knee pain which could be used in the development of novel rehabilitative approaches for individuals with PFPS.