Cortical hypertrophies in cementless short stem total hip arthroplasty in young patients under 60 years and elderly patients over 75 years-analysis of outcome and risk factors for cortical hypertrophies.

BACKGROUND: Cortical hypertrophy (CH) is a common radiological finding associated with short-stem total hip arthroplasty (THA), but its clinical significance remains unclear. This study evaluates differences in outcomes between young patients under 60 years of age and elderly patients over 75 years of age who underwent cementless short stem THA. The aim was to evaluate if there are differences in these patients depending on the presence of CH.

METHODS: A retrospective analysis of 208 short-stem THAs performed between 2014 and 2017 was conducted. Patients were divided into younger (< 60 years, n = 119) and older (> 75 years, n = 89) groups. Clinical outcomes, including Harris Hip Scores (HHS) and Oxford Hip Scores (OHS), were compared between patients with and without CH. Multivariate regression analysis was performed to identify risk factors for CH, focusing on delta hip offset, canal fill index, and stem alignment.

RESULTS: Younger patients with CH demonstrated significantly better HHS (96.1 ± 7 vs. 90.8 ± 14.3, p = 0.010) and OHS (45.8 ± 5.2 vs. 42.9 ± 8.8, p = 0.028) compared to those without CH. In older patients, the presence of CH did not significantly impact outcomes. Regression analysis identified younger age (p = 0.012), higher Canal Fill Index III (p = 0.047), and stem alignment (p = 0.049) as significant predictors of CH.

CONCLUSION: Cortical hypertrophy is associated with non-inferior functional outcomes in younger patients but shows limited clinical relevance in older patients. Implant positioning and patients demographics significantly influence the development of CH. These findings support the interpretation of CH as an adaptive response in younger, active patients rather than a pathological condition.