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How Reliable is Muscle Testing for the Osteoarthritic Hip?

Hip osteoarthritis (OA) can cause disabling pain and loss of motion. The natural result is a loss of function. Many studies of treatment for hip OA rely on pain, motion, and strength to assess results. Therefore, it's important that these measures are accurate and reliable.

In this study, the intrarater reliability of muscle strength and range-of-motion for adults with hip OA is tested. Intrarater reliability refers to the ability of one person to get the same results each time a test is given.

One physical therapist performed all of the hip joint motion and hip muscle strength testing. A handheld tool called a dynamometer was used to test and retest the strength of the hip muscles. The authors described the test position and procedure for each group of muscles.

Two special tools were used to measure (and remeasure) five of the six hip motions. The tools used included a goniometer and an inclinometer. Motions measured included flexion, extension, internal and external rotation, and abduction (movement away from the body). Photos of each test position using these tools were also included. The authors' method of reliability testing was also discussed.

The results showed good-to-excellent test-retest reliability for all tests performed. The authors attribute this in part to the way the patients were stabilized during testing.

Physical therapists performing strength and range-of-motion testing in people with hip osteoarthritis can rely on the tests as described in this study. Such tests can be used before and after treatment to measure the effect of treatment methods on motion and strength.

References: Yong-Hao Pua, BSc, et al. Intrarater Test-Retest Reliability of Hip Range of Motion and Hip Muscle Strength Measurements in Persons With Hip Osteoarthritis. In Archives of Physical Medicine and Rehabilitation. June 2008. Vol. 89. No. 6. Pp. 1146-1154.

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