Gait analysis and evaluation of knee buckling risk following total knee arthroplasty.

No one in the study actually experienced knee buckling. Knee bend and shin acceleration during walking were used as stand-ins, so the study cannot show what predicts a buckle. Only 21 patients (25 knees) from a single hospital, all within about 50 days of surgery. Walking pattern keeps changing over the months after a knee replacement, so these findings may not hold for patients further out. The exclusion numbers do not add up cleanly: 31 patients were identified and 12 are described as excluded, which would leave 19, but 21 were analysed. Everything reported is a correlation. Many relationships were tested in a small sample with no adjustment for testing so many at once, so some of the significant results could be chance. All patients had the same surgical approach (medial parapatellar, which detaches part of the vastus medialis), so the effect of the surgery itself cannot be separated from the walking findings. One step per patient, walking barefoot at a comfortable speed, was analysed. Nothing here covers stairs, faster walking, or walking in shoes.

The study received no specific grant from any funding agency in the public, commercial or not-for-profit sectors, and the authors declared no conflicts of interest relevant to the article.

Do not read this as showing what causes knee buckling or how to prevent it. None of the 21 patients actually buckled, and the study measured walking mechanics and position sense at a single point in time. The link between poorer position sense and more knee bend at foot contact describes how these patients walked; it is not proof that one causes the other.