Are Range of Motion Measurements Needed When Calculating the Harris Hip Score?

Often the patient-reported outcome (PRO) component of the Harris Hip Score (HHS) is completed, but the physician-assessed range of motion (ROM) component is not. The PRO component only is called a modified Harris Hip Score (mHHS). The purpose of this study was to determine if a statistically significant or clinically meaningful difference existed when calculating the HHS with and without the physician-reported ROM portion.

Included patients had complete HHS data (both physician and PRO components). Surgical procedure (primary or revision) was recorded for each subject. American Society of Anesthesiologists score was divided into low and high groups. Body mass index was divided into 4 categories. The study used a repeated measures design.

Data on 483 patients were collected between 12 and 60 months postoperatively (mean follow-up: 32.5 months, mean age: 55.9 ± 13.5 years). A mean difference of 4 points existed between the 2 groups: HHS group average score was 84.56 ± 13.18, and mHHS group average score was 88.74 ± 13.77. American Society of Anesthesiologists score, body mass index, and surgical type demonstrated a significant interaction with the HHS calculation method (P < .001). Primary total joint patients demonstrated a greater difference between the 2 scoring methods compared with revision patients.

No clinically meaningful difference in outcomes was found between the mHHS and the HHS. The calculation of the HHS is dependent on the inclusion of the ROM measurement. However, the small point difference between the HHS and mHHS indicates that the mHHS is still useful as an accurate determinant of patient clinical outcome, and ROM assessment is not essential.