Revision Risk in a Cohort of US Patients Younger Than 55 Undergoing Primary Elective Total Hip Arthroplasty

Background: As indications for elective total hip arthroplasty (THA) expand to younger patients, we sought to (1) compare revision risk following primary elective THA in patients <55 years at the time of their THA to patients aged >65 years and (2) identify specific risk factors for revision in patients <55 years. Methods: A Kaiser Permanente's total joint replacement registry was used to conduct a cohort study including primary elective THA patients aged >18 (2001-2018). In total, 11,671 patients <55 years and 53,106 patients >65 years were included. Multiple Cox regression was used to evaluate cause-specific revision risk, including septic revision, aseptic loosening, instability, and periprosthetic fracture. Stepwise Cox regression was used to identify patient and surgical factors associated with cause-specific revision in patients <55 years. Results: Patients <55 years had a higher risk of septic revision (hazard ratio [HR] = 1.30, 95% confidence interval [CI] = 1.02-1.66), aseptic loosening (HR = 2.60, 95% CI = 1.99-3.40), and instability (HR = 1.35, 95% CI = 1.09-1.68), but a lower risk of revision for periprosthetic fracture (HR = 0.36, 95% CI = 0.22-0.59) compared to patients aged >65 years. In the <55 age group, risk factors for septic revision included higher body mass index, drug abuse, and liver disease. Hypertension, anterior approach, and ceramic-on ceramic were associated with aseptic loosening. White race, American Society of Anesthesiologists classification >3, smoker, paralysis, posterior approach, ceramic-on-ceramic, and smaller head diameter were associated with instability. Conclusion: Identified risk factors varied depending on the cause for revision. Although septic revisions were related to patient characteristics, more modifiable factors, such as implant or surgical approach, were associated with revision due to aseptic loosening and instability. Level of Evidence: III.

Automated summary

This study compared the risk of revision following primary elective total hip arthroplasty (THA) in patients <55 years with those >65 years and identified specific risk factors for revision in the <55 age group. The results showed that patients <55 years had a higher risk of septic revision, aseptic loosening, and instability, but a lower risk of revision for periprosthetic fracture compared to patients >65 years. Various patient and surgical factors were associated with different causes of revision in the <55 age group.