Long-Term Risk of Lumbar Fusion Surgery Following Total Hip or Knee Arthroplasty: A Nationwide Cohort Study

Objective: To assess the long-term incidence of lumbar fusion surgery and its risk factors following total hip arthroplasty (THA) and total knee arthroplasty (TKA), using data from a South Korean nationwide cohort.Methods: The analysis included 528 patients who underwent THA and 2,978 who underwent TKA during 2005-2013, together with controls propensity-matched at a 1:20 ratio by age, sex, and screening year.The primary outcome was subsequent lumbar fusion surgery, identified from National Health Insurance Service procedure codes.Cox models were used to estimate adjusted hazard ratios (aHRs), and subgroup analyses were conducted by age, sex, body mass index, cholesterol level, and income.Results: Over a mean follow-up of 3.5 years for THA and 2.8 years for TKA, the risk of lumbar fusion surgery was significantly higher after THA (aHR, 2.66; 95% confidence interval [CI], 1.13-6.22)and TKA (aHR, 1.97; 95% CI, 1.46-2.67)than among matched controls.The associations were stronger in men than in women and in adults aged ≥60 years than in younger adults.Among patients who underwent TKA, overweight status, lower cholesterol levels, and higher income were associated with higher risk.Conclusion: Compared with matched controls, patients who underwent THA or TKA had a higher long-term risk of subsequent lumbar fusion surgery.This association was stronger in older adults and men.These findings emphasize the importance of considering lumbar spine health in the care of patients undergoing lower limb arthroplasty.