Dynamic knee joint stiffness and contralateral knee joint loading during prolonged walking in patients with unilateral knee osteoarthritis.
Jonathan A Gustafson, William Anderton, Gwendolyn A Sowa and 2 others
PMID 30453143WHAT IT FOUND
In unilateral knee OA, the painful knee was stiffer during walking, and modelled knee joint forces rose after 30 and 45 minutes in both knees.
The non-painful knee also had higher late-stance forces.
Key findings
01The painful knee was stiffer during walking than the non-painful knee, with an average difference of 13%, but stiffness did not change across the walking bout.
02After 30 and 45 minutes of walking, the first peak knee joint force averaged across both knees was 18% and 25% of body weight higher than baseline.
03The non-painful knee had a higher second peak knee joint force than the painful knee, with a difference of 41% of body weight.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study did not follow patients over time, so it cannot show whether these force changes lead to pain or OA progression. Knee joint forces were predicted by a model, not measured directly inside the knee. Because participants were compared with themselves, it is hard to tell whether the non-painful knee was overloaded or the painful knee was underloaded. The model did not separate medial and lateral knee compartment loading. Muscle activity was not measured, and the generic muscle model may underestimate actual muscle forces. Some non-painful knees had radiographic OA, so the comparison was not between a diseased knee and a completely healthy knee. The sample was small and exploratory.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that prolonged walking damages the knee or that rest breaks are proven. This study measured modelled knee forces, not pain, injury or disease progression, and it did not compare walking schedules.