Male Range of Motion Norms in the Haemophilia Joint Health Score Underrepresent the Severity of Joint Damage in Females

INTRODUCTION: Joint bleeding causes haemarthropathy, impacting quality of life. Joint outcomes research in bleeding disorders has focused on males; however, females are also affected. The Haemophilia Joint Health Score (HJHS) is a validated physical exam measure of haemarthropathy, which includes flexion and extension loss parameters derived from male range of motion (ROM) norms. Female ROM norms are not included in the HJHS instruction manual. AIM: To determine whether using female ROM norms, rather than standard male ROM norms, yields revised HJHS values in females with bleeding disorders. METHODS: Participants assigned female at birth with bleeding disorders and clinical HJHS exams at the University of Colorado were included in analysis. HJHS was calculated by standard methods, including flexion and extension loss measures comparing joint angles to the contralateral side and to normative male and female ROM angles. The frequency and magnitude of Score Revisions when applying female ROM norms were calculated and compared across individual joints (ankle, knee, elbow), joint pairs, and participants. RESULTS: The analysis included 187 females with 448 HJHS exams. At least 1 Score Revision occurred when applying female ROM norms in 92/187 participants (49.2%) across 184/448 exams (41.1%). When using the female rather than male ROM norms, the 6-joint total HJHS revision was 0.67 ± 1.29 (mean ± standard deviation) points higher (p < 0.001). Applying male ROM norms underestimated the total HJHS in 136 (33.8%) exams. Ankles joints were most frequently underestimated. CONCLUSION: Applying male ROM values to HJHS calculations in females with bleeding disorders underestimates haemarthropathy, particularly in the ankle.