Abnormal loading and functional deficits are present in both limbs before and after unilateral knee arthroplasty.
A J Metcalfe, C J Stewart, N J Postans and 4 others
PMID 28437757WHAT IT FOUND
The main measure of load on the other knee did not show a change after unilateral knee replacement.
Gait remained abnormal in both legs, and pre-operative gait function was linked to post-operative recovery.
Key findings
01The pre-specified primary gait measure, adduction moment impulse at the unaffected knee, did not change significantly after surgery.
02Frontal plane moments at the knees and hips showed some improvement after surgery but did not return to normal, especially on the unaffected side.
03A pre-operative objective function score below 0.7 classified post-operative normal function 13 out of 15 times on the affected leg and 12 out of 15 times on the unaffected leg.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 15 of the original 20 OA patients returned for post-operative gait analysis, so the follow-up sample was small. Patients were highly selected: they had unilateral medial compartment disease and no pain, ache or niggle in the other lower limb, so results may not apply to typical knee OA patients with symptoms elsewhere. All analyses except the unaffected-knee adduction moment impulse were secondary exploratory analyses, and multiple testing corrections were not performed. The pre-operative threshold for prediction was created after looking at the data, and the classifier was trained on the same pre-operative data, so it needs testing in new patients. The study describes gait patterns and associations; it does not test whether pre-operative rehabilitation changes outcomes.
Declared interests
No conflicts of interest were declared.
The easy way to misread this
Do not conclude that unilateral knee replacement will normalise gait in both legs or that surgery protects the other knee. The pre-specified unaffected-knee load measure did not show a change, and gait abnormalities remained after surgery.