Functional capacity and early radiographic osteoarthritis in middle-aged people with chronic knee pain

In order to improve the physiotherapeutic treatment of patients with long-standing knee pain, it is important to identify osteoarthritis (OA) of the knee at an early stage. The aim of the present study was to test the value of single functional measurement variables with the focus on the lower extremities for the association to early radiographic signs of OA of the knee. The classification by Ahlbäck grade I (joint space narrowing) was used in a cohort of 204 individuals aged 35-54 years with long-standing knee pain.

The following five selected tests were employed: three tests of static and dynamic balance (Balance I-III); one test of muscle strength (one-leg-rising-test, OLR); and one test of walking ability (time for walking 300 m indoors). Odds ratios (ORs) were calculated with a 95% confidence interval.

Results revealed that the selected tests of functional capacity due to rather low sensitivity (0.15-0.81), specificity (0.21-0.86) and inconclusive odds ratios (0.78-1.62) are probably of limited value as assessment tools to find radiographic knee OA in a younger population with mild OA. However, it is also possible to conclude that in middle-aged individuals with chronic knee pain, the diagnosis of radiographic OA is not related to the functional capacity as measured in the present study.