Strength and functional deficits in individuals with hip osteoarthritis compared to healthy, older adults

Abstract

Purpose: Hip osteoarthritis (OA) compromises quality of life for many individuals. This study quantified deficits in functional capacity for use in rehabilitation goal setting by combining assessments of muscle strength, function and physical activity in patients with hip OA and healthy adults.

Method: Twenty-six patients with end-stage hip OA and 18 healthy adults participated. Isometric muscle strength around the hip and knee was measured. Function was assessed using stair climbing, five-time-sit-to-stand, timed-up-and-go and 6-minute walk tests. The UCLA activity rating scale assessed physical activity. Analyses of covariance (ANCOVA) were used to assess differences between groups.

Results: Patients had 30% less knee extensor (p < 0.001), 38% less knee flexor (p < 0.001), 10% less hip flexor (p = 0.47), 23% less hip extensor (p = 0.24) and 17% less hip abductor strength (p = 0.23) than healthy adults. Hip adductor strength was equal between groups (p = 0.93). Patients were 50% slower on the stair climbing test (p = 0.001), 34% slower on the timed-up-and-go test (p = 0.004), 34% slower on the five-time-sit-to-stand test (p = 0.001), and walked 28% less during the 6-min walk test (p < 0.001). Patients were less physically active (p = 0.001).

Conclusions: Patients had deficits in muscle strength, function and physical activity compared to healthy adults. Quantifying these deficits provides benchmarks for improvement during rehabilitation.

Implications for rehabilitation: Hip osteoarthritis (OA) affects up to 28% of adults over the age of 65 and many individuals report functional and activity limitations directly related to their arthritic condition, posing a risk for future morbidity Total hip arthroplasty (THA) is the treatment of choice for decreasing pain and improving function, however, some individuals suffering from end-stage hip OA are not candidates for THA, and effective rehabilitation interventions to improve physical function are crucial Establishing estimates of the deficits in muscle strength, physical function and physical activity in people with and without hip OA can aid rehabilitation professionals in their goal setting and intervention planning Rehabilitation interventions should not only consist of muscle strengthening and functional training, but interventions to improve physical activity levels are required to improve overall physical functioning and to decrease risks for additional health complications.

Figure 1

Participant enrollment flowchart.

Figure 2

(A–C). Muscle Strength Testing Positions. A) Study participant positioned on the dynamometer for hip flexor and hip extensor strength testing B) Study participant positioned on the dynamometer for hip abductor and hip adductor strength testing C) Study participant positioned on the dynamometer for knee extensor and knee flexor strength testing

Figure 3

Hip and knee muscle strength in hip OA group and healthy adult group. Mean ± standard error. * differences between groups (P<0.05).

Figure 4

Functional performance measures for participants in hip OA group and healthy adult group. Mean ± standard error. SCT= stair climbing test; FTSTS=five time sit to stand; TUG=timed up and go; 6MW= six minute walk test. *difference between groups (P<0.05).