Associations of knee extensor strength and standing balance with physical function in knee osteoarthritis

Abstract

Objective. Knee extensor strength is an important correlate of physical function in patients with knee osteoarthritis; however, it remains unclear whether standing balance is also a correlate. The purpose of this study was to evaluate the cross-sectional associations of knee extensor strength, standing balance, and their interaction with physical function. Methods. One hundred four older adults with end-stage knee osteoarthritis awaiting a total knee replacement (mean ؎ SD age 67 ؎ 8 years) participated. Isometric knee extensor strength was measured using an isokinetic dynamometer. Standing balance performance was measured by the center of pressure displacement during quiet standing on a balance board. Physical function was measured by the self-report Short Form 36 (SF-36) questionnaire and by the 10-meter fast-pace gait speed test. Results. After adjustment for demographic and knee pain variables, we detected significant knee strength by standing balance interaction terms for both SF-36 physical function and fast-pace gait speed. Interrogation of the interaction revealed that standing balance in the anteroposterior plane was positively related to physical function among patients with lower knee extensor strength. Conversely, among patients with higher knee extensor strength, the standing balancephysical function associations were, or tended to be, negative. Conclusion. These findings suggest that although standing balance was related to physical function in patients with knee osteoarthritis, this relationship was complex and dependent on knee extensor strength level. These results are of importance in developing intervention strategies and refining theoretical models, but they call for further study.

Laboratory-based measurement of standing balance in individuals with knee osteoarthritis: A systematic review

“…The same five studies reported values for ML range (Collins et al, 2012;Hunt et al, 2009;Pua et al, 2011;Turcot et al, 2011;Vahtrik et al, 2014). Two studies reported on a DOF task, with one study finding an average range of 16.2 mm 22 , while the other reported a range of normalized values (see above) from 0.01 to 0.02 m −1 (Vahtrik et al, 2014).…”

“…Five studies reported values for AP range (Collins et al, 2012;Hunt et al, 2009;Pua et al, 2011;Turcot et al, 2011;Vahtrik et al, 2014). Of the five, three reported on SOF tasks with results ranging from 27.9 to 42.5 mm (Collins et al, 2012;Hunt et al, 2009;Turcot et al, 2011).…”

“…Five studies reported values for the AP and ML standard deviation, with all values reported below pertaining to AP and ML, respectively (Collins et al, 2012;Hirata et al, 2013;Hunt et al, 2009;Pua et al, 2011;Takacs et al, 2014). Two studies looked at DOF conditions, finding average values of 4.8-5.4 mm and 1.2-3.4 mm (Hirata et al, 2013; Pua et al, Table 2 Quality index scores.…”

“…All other items of the quality assessment index were satisfied in at least 70% of the included articles. Table 3 summarizes the COP data reported for 14 studies that measured COP using a floor-mounted force platform under six conditions: eight studies on double leg stance (DLS) with EO on a firm surface (DOF) (Hirata et al, 2013;Hong et al, 2013;Ishii et al, 2013;Lyytinen et al, 2010;Masui et al, 2006;Pua et al, 2011;Sorensen et al, 2014;Vahtrik et al, 2014); one study on DLS with EO on a soft surface (DOS) (Hirata et al, 2013); four studies on DLS with EC on a firm surface (DCF) (Hirata et al, 2013;Hong et al, 2013;Lyytinen et al, 2010;Masui et al, 2006); one study on DLS with EC on a soft surface (DCS) (Hirata et al, 2013); eight studies on single leg stance (SLS) with EO on a firm surface (SOF) (Birmingham et al, 2001;Cho and Hwang, 2013;Collins et al, 2012;Hunt et al, 2009;Hunt et al, 2010;Lyytinen et al, 2010;Takacs et al, 2014;Turcot et al, 2011); and one study on SLS with EO (Birmingham et al, 2001). Three of the DLS studies specified that the feet be together (Ishii et al, 2013;Masui et al, 2006;Sorensen et al, 2014) and one study examined balance with shoes on rather than barefoot (Birmingham et al, 2001).…”

Preoperative gluteus medius muscle atrophy as a predictor of walking ability after total hip arthroplasty

“…Studies have shown that the knee extensor strength correlates with walking speed and stair climbing performance in patients after total knee arthroplasty 25,26) . In particular, our earlier study suggested that the preoperative knee extensor strength on the affected side might be a good predictive factor of the future ambulatory status, such as the use of an assistive device in daily living 10) .…”