The effectiveness of an exercise programme on knee loading, muscle co-contraction, and pain in patients with medial knee osteoarthritis: A pilot study

• The effectiveness of exercise on muscle co-contraction and loading was investigated.
• Muscle co-contraction decreased on the lateral side of the knee joint.
• Knee joint loading was not altered, whilst pain was reduced.
• The reduction in pain was not due to alteration of the kinetics.
• The reduced muscle co-contraction suggests that exercises increase stability.

BackgroundOsteoarthritis (OA), which increases knee loading, muscle co-contraction, and pain, is a mechanical disease that requires biomechanical exploration to reduce pain in the knee. Therefore, this article aims to investigate the effectiveness of an exercise programme on the aforementioned outcomes in people with medial knee OA.MethodsCohort pilot study design. A total of 19 patients with knee OA attended a six-week group exercise programme integrated with self-management education. The following outcomes were assessed before and after the exercise programme: external knee adduction moment (EKAM), knee adduction angular impulse (KAAI), knee antagonist muscle co-contraction, and pain subscale of the knee injury and osteoarthritis outcome score (KOOS).ResultsOf the 19 patients, 14 completed the study. The EKAM and KAAI did not show statistical significance post-exercise intervention (p = 0.21-0.7 and 0.56, respectively). Muscle co-contraction between vastus lateralis and biceps femoris muscles decreased in early-stance (64.78 (44.35) compared with 38.10 (23.10), p = 0.01) and mid-stance (27.62 (32.12) compared with 14.94 (17.40), p = 0.04). A corresponding significant pain reduction was observed (p = 0.00) with a median (range) of 51.50 (47.00 to 62.50) at week 6 compared with 34.50 (29.25 to 41.25) at baseline.ConclusionThis is the first known study to explore the effect of an exercise programme on knee loading and muscle co-contraction in patients with OA. Although the value of EKAM did not change, the findings suggest that the reduction in vastus lateralis and biceps femoris co-contraction might be the mechanism behind the reduction of pain.