Causes of Chronic Hip Pain Undiagnosed or Misdiagnosed by Primary Physicians in Young Adult Patients: a Retrospective Descriptive Study

Background: Hip pain is a common musculoskeletal complaint in general practice. Although comprehensive diagnostic approach on hip pain is mandatory for adequate treatment, un- or mis-diagnosis is not rare in primary care. The aim of this study was to analyze descriptively un- or mis-diagnosed hip pain cases referred from primary care to a tertiary hospital, especially in young adults ${\leq}50years\;old$. Methods: We retrospectively analyzed a consecutive cohort of 150 patients (${\leq}50years\;old$) with chronic hip pain (${\geq}6weeks$), which was not diagnosed or misdiagnosed based on the information provided on the referral form. Results: Overall an average 32 cases/month were referred due to hip pain without a diagnosis or with an incorrect diagnosis. Among them, 150 patients were enrolled in this study and 146 (97.3%) could be allocated to a specific disease by using data from routine clinical practice. Four common final diagnoses were femoroacetabular impingement (FAI) syndrome (55.3%), hip dysplasia (HD, 13.3%), referred pain from the lumbar spine (9.3%), and spondyloarthritis (SpA, 7.3%). In patients with FAI syndrome, 37 (44.0%) had pincer-type FAI and 33 (39.8%) had combined-type. Although the pain site or gender was not tightly clustered, the distribution of final diagnosis was significantly different according to hip pain location or gender. Especially, SpA or HD was not observed in younger women subgroup or elder men subgroup, respectively, when stratified by the mean age of participants. Conclusion: Most (> 80%) young patients with hip pain, a difficult issue to diagnosis for many primary physicians, had FAI syndrome, HD, spine lesions, and SpA. This study could give a chance to feedback information about cases with un- or mis-diagnosed hip pain, and it suggests that primary physicians need to be familiar with the diagnostic approach for these 4 diseases.