Data on hip joint rotation range of motion (ROM) are rare; the methods of measurement vary and reproducibility has not been evaluated, in particular in relation to the subject's position (prone or supine, seated).
Hypothesis
Hip joint rotation ROM is symmetrical, and ROM is not modified by the patient's position when data is obtained.
Patients and methods
This series included 120 adults between 20 and 60 years old (71 women, 49 men), who had no hip, spine or lower extremity disorders. External (ER) and internal (IR) rotation ROM was obtained using a photographic method by two observers. Measurements were obtained with the patient in three positions: the dorsal decubitus (supine) (P1), and ventral decubitus (prone) (P2) with the hip in extension and seated with the hip in flexion (P3).
Results
Hip rotation ROM was P1: 68.1° (ER = 38.5°; IR = 29.6°); P2: 77.1°(ER = 41.8°; IR = 35.2°); P3: 78.5° (ER = 78.5°; IR = 37.9°) with no significant difference among the three positions. Interobserver reproducibility was satisfactory (concordance correlation coefficient (ccc) 0.7) and was comparable in the three positions with a ccc of 0.7072 (P1), 0.7426 (P2) and 0.7332 (P3), respectively. Hip rotation ROM balance was ER predominant in 47.5%, neutral in 39.5% and IR predominant in 13%. Hip rotation ROM balance was symmetric in both hips in 73 subjects (61%). Hip rotation ROM was reduced with age (P < 0.0001), and was 4.7° less in men (P = 0.0078), and in overweight subjects (P < 0.0006).
Discussion
Our values are probably lower than those in the literature because of the difference in study population. In our series, age, BMI and gender seemed to be determining factors. Hip rotation ROM balance is usually ER predominant or neutral. Hip rotation ROM can be measured in the three positions with no significant difference, with satisfactory interobserver reproducibility for each.
