Perceived Instability Is Associated With Strength and Pain, Not Frontal Knee Laxity, in Patients With Advanced Knee Osteoarthritis.

The study collected data at one time point, so it cannot show whether strength training, pain reduction, or other treatment changes perceived instability. The sample was smaller than the planned 42 participants, and the planned sample size was not chosen for subgroup analyses. Patients unable to walk 10 m unaided, those with body mass index greater than 45 kg/m2, and those with lateral-compartment or revision knee disease were excluded, so findings may not apply to those groups. Perceived instability was measured with one question, and varus/valgus laxity was measured only passively under anesthesia in full extension. The decision to proceed with TKA was made between patient and clinician, which may introduce selection bias.

Do not conclude that frontal knee laxity explains perceived instability, because laxity did not differ between groups and was not associated with instability. Do not conclude that strength training reduces instability, because no intervention was tested and data were collected at one time point.