Background Congenital and acquired structural hip abnormality are frequently associated with premature hip osteoarthritis (OA) requiring arthroplasty at younger ages. However, in routine orthopaedic practice, hip arthroplasty is frequently conducted in younger patients with no clearly identified underlying cause for premature arthrosis of the hip.

Objectives The aim of this study was to explore whether underlying comorbidity, contributing to development of premature hip OA, could be identified from reviewing pelvic radiographs and medical charts.

Methods The last 100 patients aged <50, undergoing hip arthroplasty were identified from the hospital coding database at Aintree University Hospital. Medical note review was available for 92. Retrospective record review recording pre-existing history of structural hip abnormality, history of known inflammatory arthropathy and presence of known metabolic comorbidity associated with arthropathy were recorded along with the presence of obesity. Pelvic radiographs were examined by 2 independent reviewers. Where sacroiliac joints (SIJ) were included the presence of radiographic sacroiliitis was recorded and SIJs were graded using New York radiographic criteria [1].

Results Chart review was conducted for 92 cases. Known prior structural abnormality was recorded in 24 (26.1%), known inflammatory arthropathy in 3 (3.3%) and 65 (70.7%) had no diagnosis of underlying hip structural abnormality or inflammatory arthropathy. In the whole cohort, 26 (28.3%) were obese (BMI≥30kg/m²). Detailed chart and investigation review identified one patient with underlying haemaochromatosis. This was diagnosed post arthroplasty. Inflammatory markers were measured in 41 (44.6%) and of these 10 (24%) had a CRP or ESR above the normal laboratory range. Pelvic radiographs that included sacroiliac joints were available for 83 participants. SIJ abnormality was observed in 9 (10.8%) with 5 (6%) having bilateral grade 2 sacroiliitis. None of these patients were known to have a diagnosis of ankylosing spondylitis or axial spondyloarthritis (Axial SpA).

Conclusions This study has highlighted that younger patients undergoing hip arthroplasty do not have routine screening for underlying comorbidity contributing to premature OA. The high prevalence of SIJ abnormality observed in this cohort may represent undiagnosed axial SPA. Clear guidelines for routine screening for underlying comorbidity in this patient group are recommended.

References

1. Van der Linden S., Valkenburg H.A., Cats A. (1984) Evaluation of diagnostic criteria for anylosing spondylitis. A proposal for modification of the New York criteria. Arthritis Rheum 27:361-368

Disclosure of Interest None declared