Functional Impairment in Aseptic Loosening of Total Hip Arthroplasty: The Role of Defect Severity, Osteolysis Burden, and Fixation Type

Background: Aseptic loosening remains a major indication for revision total hip arthroplasty. The relationship between functional impairment and structural disease burden is clinically relevant but not fully quantified.

Objective: To evaluate whether Harris Hip Score is associated with Paprosky defect severity, computed tomography based osteolysis volume, anatomical osteolysis distribution, and fixation type in patients revised for aseptic loosening.

Methods: Sixty patients revised for aseptic loosening were analyzed, including 30 cemented and 30 cementless implants. Harris Hip Score was evaluated in relation to Paprosky defect type, femoral, acetabular, and total osteolysis volumes, and Gruen and DeLee and Charnley zone involvement. Multivariable linear regression, interaction models, sensitivity analyses, and influence diagnostics were performed.

Results: Harris Hip Score was lower in cementless than cemented implants (35.4 ± 11.42 versus 57.95 ± 9.24; p < 0.001). Functional score declined progressively with increasing Paprosky severity. In the primary adjusted model, Paprosky score was independently associated with lower Harris Hip Score (B = -6.18; p < 0.001), while cementless fixation remained independently associated with lower score (B = -17.01; p < 0.001). The model explained 88.0% of Harris Hip Score variation. Adding osteolysis-volume variables minimally improved model performance. Sensitivity analyses confirmed the stability of the main predictors.

Conclusions: Functional impairment in aseptic loosening after total hip arthroplasty is most strongly associated with Paprosky defect severity and fixation type. Computed tomography based osteolysis volume and anatomical zone mapping provide complementary structural information for revision planning.