The Semantics of ‘Hip Pain’ and its Impact on Clinical Practice in Patient-Reported Outcome Measures (PROMs) of Disease: Results from a Clinical and Radiological Evaluation Cohort

INTRODUCTION: The item ‘hip pain’ is widely used in questionnaires related to Spondyloarthritis and/or Ankylosing spondylitis (AS), either in clinics with patients being physically present or remotely, as the hip joint is known to affect AS in particular. Patients in clinics often claim to have hip pain. However, by stating “hip” they are referring to variable structures located in the hip region not necessarily related to hip joint itself. OBJECTIVE: To assess which structure(s) patients mean when referring to hip pain. METHODS: A diagram used as a proforma for patients to indicate the site of ‘hip pain’ following a detailed history and examination was used. Radiological imaging was utilised for those patients with multiple sites or clinically unclear causes of “hip” pain. RESULTS: From 54 patients 7 different anatomical sites described which were: Trochanter, (27.2%), hip joint (20.8%), iliac crests (anterior superior [6.9%], posterior superior [8.3%], and anterior inferior [4.1%]), lumbar spine (8.3%), sacroiliac joint (6.9%). More than 1 sites in the same patient: (17.5%). Diagnoses were: Trochanteric bursitis (27%), osteoarthritis of hip and spine, (25%), enthesitis (22%), sacroiliitis (6.7%), synovitis (5%), fibromyalgia (3.4%), and hip dislocation (1.6%). More than 1 diagnosis in same patient: 9.3%. CONCLUSION: ’hip pain’ as an item used in questionnaires must be interpreted with caution.