Hip Dysplasia Diagnosed After Skeletal Maturity: Factors Associated With Progression to Osteoarthritis.

Background: Hip dysplasia diagnosed after skeletal maturity is distinct from developmental dysplasia of the hip (DDH) in infants and young children. While the natural history of DDH in infants and young children is well-established, the association between hip dysplasia diagnosed after skeletal maturity and osteoarthritis is less clear. This narrative review summarizes existing literature assessing characteristics of hip dysplasia diagnosed after skeletal maturity associated with progression to osteoarthritis.

Methods: Publications were identified from a PubMed search. Three reviewers screened articles for studies that longitudinally assessed progression to osteoarthritis, disability, or arthroplasty for individuals with untreated hip dysplasia identified after skeletal maturity. In total, 13 articles met screening criteria, including 7 prospective cohorts, 2 case-control studies, 1 retrospective case series, 1 cross-sectional analysis, and 2 retrospective cohort studies.

Results: Most studies reported an association between radiographic hip dysplasia and development of osteoarthritis over time,^1-10 though some studies questioned the association between simple radiographic measures of dysplasia and joint degeneration.¹¹ Joint subluxation and incongruity, history of hip pain, and any evidence of radiographic osteoarthritis at the initial time-point were all reliably associated with future joint degeneration. Though many studies confirmed at least an association between the center edge angle of Wiberg and future osteoarthritis development, there was evidence proposed that clinical factors (age, sex, body mass), novel radiographic markers, and pathologic joint mechanics are significant contributors to joint failure.

Conclusion: Hip dysplasia diagnosed after skeletal maturity is associated with development of osteoarthritis beyond 10 years in the majority of published literature, though some studies question the reliability of simple radiographic measures as predictors of osteoarthritis development. Previous literature is limited by small sample size, follow up duration, low diversity in the population, and variable methods characterize severity of hip dysplasia and hip joint failure. Overall, evidence of hip subluxation and incongruity, female sex, more severe dysplasia, and low and high body mass are associated with development of osteoarthritis. Future studies should focus on large, diverse populations with follow up of at least 20 years and consider advanced metrics to quantify pathologic joint mechanics to predict hip joint failure. Level of Evidence: IV.