The contralateral knee may not be a valid control for biomechanical outcomes after unilateral total knee arthroplasty.

The study measured gait only after surgery, with no pre-operative motion data, so it cannot show that arthritis in the other knee caused the movement differences. Only 53 people were analysed, and the authors state they may not have had enough power to detect all true differences. People with substantial health comorbidities were excluded, so the findings may not apply to all patients after TKA. The study did not assess strength, proprioception, or instability, so other factors could explain reduced knee motion. The paper did not show how large a difference in knee excursion is clinically important. Pain was measured with a single question, and the groups were defined by X-ray grade rather than MRI or joint space width.

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Do not conclude that symmetrical walking means both knees have recovered. In this study, the group with arthritis in the non-operated knee had symmetrical but abnormal knee motion, while the group without arthritis had asymmetry because only the operated knee was abnormal.