Passive Hip Internal and External Rotation and Hip Flexion
ICF category	Measurement of impairment of body function: mobility of a single joint
Description	The amount of passive hip rotation and passive hip flexion measured prone and supine, respectively. Although assessing the range in all 6 directions (3 planes) of hip motion is important in patients with hip OA, for brevity, we included the 3 most commonly limited hip motions. The patient is also asked to rate the amount of pain experienced during the movement on a 0-to-10 numerical pain rating scale (NPRS).
Measurement method	Hip Internal and External Rotation: The patient is positioned prone with feet over the edge of the treatment table. The hip measured is placed in 0° of abduction, and the contralateral hip is placed in about 30° of abduction. The reference knee is flexed to 90°, and the lower extremity is passively moved to produce hip rotation. The movement arm of the goniometer is aligned vertically along the shaft of the tibia while the stationary arm is aligned along an imaginary vertical line. Manual stabilization is applied to the pelvis to prevent pelvic movement and also at the tibiofemoral joint to prevent motion (rotation or abduction/adduction), which could be construed as hip rotation.78 The tibia is then moved in the frontal plane to produce hip internal and external rotation. The motion is stopped and measurements taken when the extremity achieves its end range of passive hip rotation or when pelvic movement is necessary for additional movement of the lower extremity. An inclinometer may also be used to measure hip rotation. The inclinometer is first “calibrated” by placing it along the distal shaft of the vertically aligned tibia, just proximal to the medial malleolus and then setting the inclinometer dial to zero. Then, the extremity is passively moved to produce hip rotation and inclinometer measure is taken when the hip achieves its end range of passive internal and external rotation.47 Hip Flexion: With the patient in the supine position, the hip is passively flexed with the movement arm of the goniometer along the long axis of the femur and the stationary arm of the goniometer along the long axis of the trunk, while stabilizing the lumbar spine to avoid any posterior pelvic tilt.83
Nature of variable	Continuous (ROM) and ordinal (pain)
Units of measurement	Degrees and 0-to-10 NPRS
Measurement properties	Limited ROM is associated with high levels of disability in patients with hip OA.172 The reliability for hip rotation and hip flexion ROM measurements has been shown to be excellent, ICC of 0.95 to 0.9747 for rotation and ICC of 0.94 (95% CI: 0.89–0.97)30 for flexion. ROM measurements in 22 individuals with hip OA demonstrated excellent intrarater test-retest reliability (ICC = .97) for hip flexion.152 Croft et al38 showed good agreement among 6 testers when assessing for hip rotation and hip flexion in patients with hip OA. Steultjens et al172 also showed good reliability when assessing the hip joint in patients with OA. The MDC95 for hip flexion, determined using 22 patients with knee OA and 17 subjects without lower extremity symptoms or known pathology, is 5°, meaning any change more than 5° is considered to be change beyond measurement error.30 The MDC95 for pain with hip flexion is 1.2 on the 0–10 NPRS.30 The clinically important difference for the NPRS, derived from patients with low back pain, has been shown to be a reduction of 2 points.27,51