Physical examination findings and their relationship with performance-based function in adults with knee osteoarthritis.

Background: Many physical examination (PE) maneuvers exist to assess knee function, none of which are specific to knee osteoarthritis (KOA). The Osteoarthritis Research Society International also recommends the use of six functional performance measures to assess function in adults with KOA. While earlier studies have examined the relationship between PE findings and self-reported function or PE findings and select performance tests in adults with knee pain and KOA, few have examined the all three types of measures. This cross-sectional study specifically examines the relationships between results of PE findings, functional performance tests and self-reported function in adults with symptomatic KOA.

Methods: We used baseline PE data from a prospective randomized controlled trial in 87 participants aged ≥40 years with symptomatic and radiographic KOA. The PE performed by three experienced physical therapists included: muscle assessment, function and special tests. Participants also completed functional performance tests and the Western Ontario and McMaster Osteoarthritis Index (WOMAC). Multivariate linear regression identified contributions of PE findings towards functional performance and WOMAC scores, adjusting for age and gender.

Results: Participants' mean age was 60.4 years (SD = 10.5), mean disease duration was 8.4 years (SD = 10.1) and 27 participants had varus knee alignment. Mean WOMAC pain and function scores were 211 (SD = 113) and 709 (SD = 394), respectively. Weakness was present in major hip and knee muscles. Seventy-nine participants had a positive Ely's, 65 a positive Waldron and 49 a positive Grind. Mean 6-min walk was 404 m (SD = 83) and mean Berg Balance was 53 (SD = 4). Regression analysis identified positive findings on 5 special tests (P < 0.05) as indicative of poorer 6 min walk. Positive Apley's was associated (P < 0.05) with slower 20 m walk and a positive Ober with poorer balance scores (P < 0.05).

Conclusions: Diminished hip muscle strength and flexibility, and patella dysfunction were prevalent in these adults with symptomatic KOA. Results of functional performance tests suggest balance and walking ability are impaired and are associated with PE findings of muscle length imbalance, hip muscle weakness and patella dysfunction. None of the PE measures were associated with self-reported function. Therefore, performance-based test results may be more useful in informing rehabilitation interventions.