Background: Abnormal range of motion (ROM) is a common sign of pathology in the pediatric hip, yet there are little data in the literature defining what the normal hip ROM is in children. The purpose of this study was to establish normative values for hip ROM in children of varying ages.
Methods: We performed an Institutional Review Board approved, prospective study of otherwise healthy patients receiving fracture care at our institution. Inclusion criteria were boys and girls aged 2 to 17, who were being treated for an isolated upper extremity injury and who had no underlying musculoskeletal condition, history of lower extremity injury, or other systemic diagnosis. All patients were evaluated with a standard measurement technique using the same double-long-armed goniometer. Supine abduction, adduction, and hip flexion were measured with care taken to stabilize the pelvis. Internal and external rotation in flexion were assessed with both the hip and knee flexed to 90 degrees. In the prone position, hip extension was recorded as was internal and external rotation in extension. Left and right measurements were averaged to produce a single data point for each index. On the basis of a power analysis (to detect a minimal detectable difference of 6 degrees), 2 separate cohorts of 23 patients were randomly selected for the assessment of intraobserver and interobserver reliability.
Results: We measured 504 hips in 252 pediatric patients, including 163 boys and 89 girls. We found a decreasing trend in ROM for almost all indices with advancing age, although this decline was less apparent among girls. Intraobserver reliability demonstrated excellent agreement (intra class correlation coefficient>0.81) for all indices. Interobserver assessments revealed excellent agreement for abduction, external rotation in flexion, internal rotation in extension, and external rotation in extension. Substantial agreement (intra class correlation coefficient, 0.61 to 0.8) was found for adduction, flexion, extension, and internal rotation in flexion.
Conclusions: Normative values for hip ROM in children of varying ages have been established with acceptable intraobserver and interobserver reliability.
Level of evidence: Level II (Diagnostic).