JOA - 2026-05-22 - Journal Article
Differential Effects of Degenerative Spine Disease and Spinal Fusion on the Risk and Progression of Hip Osteoarthritis: A Nationwide Time-Varying Cohort Study.
Hong SH, An MS, Kong SJ, Hyun CS, Han SB, Kim SM
Topics
Key Takeaway
In 1.62 million adults, spinal fusion carried a 2.32x higher hazard of progressing to THA once hip OA developed, exceeding the 1.51x hazard seen with degenerative spine disease alone.
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Summary
This nationwide time-varying cohort study examined whether degenerative spine disease (SPINE_DX) or spinal fusion (SPINE_FUSION) independently increases HOA incidence and progression to THA in adults ≥50 years. Both exposures were associated with higher HOA incidence (HR 1.66 and 1.22, respectively) versus controls, with IPTW sensitivity analyses confirming these associations. Among those who developed HOA, SPINE_FUSION carried the highest THA risk (HR 2.32), exceeding SPINE_DX (HR 1.51), suggesting fusion accelerates end-stage hip disease beyond the effect of degeneration alone.
Key Limitation
The database lacks fusion-level detail, segment count, and sagittal alignment data (PI-LL mismatch, SVA), preventing determination of whether flat-back deformity or specific lumbar levels drive the disproportionate THA risk in the fusion group.
Original Abstract
BACKGROUND
The hip and lumbar spine function as an integrated biomechanical unit, and spinal pathology may influence hip joint loading. However, population-level evidence regarding whether lumbar degeneration or spinal fusion increases the risk of hip osteoarthritis (HOA) remains limited. The purpose of this study was to investigate whether degenerative spine disease and spinal fusion are associated with the incidence and progression of HOA in a nationwide cohort.
METHODS
We conducted a retrospective cohort study using the nationwide population-based database linked to the national health screening database, including individuals aged ≥ 50 years from 2010 to 2022. Spinal pathology was modeled as a time-varying exposure and classified into three groups: control, degenerative spine disease (SPINE_DX), and spinal fusion (SPINE_FUSION). Incident HOA was assessed using time-varying Cox proportional-hazards models. Among individuals who developed HOA, progression to total hip arthroplasty (THA) was evaluated using Kaplan-Meier methods and multivariable Cox models adjusting for demographic, clinical, and lifestyle factors. Inverse probability of treatment weighting (IPTW) was performed as a sensitivity analysis.
RESULTS
Among 1,620,585 individuals, HOA incidence rates were 12.31, 20.91, and 17.44 per 1,000 person-years in the control, SPINE_DX, and SPINE_FUSION groups, respectively. Compared with controls, both SPINE_DX (HR [hazard ratio], 1.66; 95% CI [confidence interval], 1.64 to 1.68) and SPINE_FUSION (HR, 1.22; 95% CI, 1.19 to 1.25) were independently associated with increased risk of incident HOA; these associations remained consistent after IPTW adjustment. Among patients who developed HOA, progression to THA was highest in the SPINE_FUSION group. Both SPINE_FUSION (HR, 2.32; 95% CI, 2.06 to 2.62) and SPINE_DX (HR, 1.51; 95% CI, 1.41 to 1.62) were associated with increased THA risk.
CONCLUSIONS
Spinal pathology was significantly associated with both the development and progression of HOA. Degenerative spine disease was strongly associated with increased HOA incidence, whereas SPINE_FUSION was associated with a higher risk of progression to end-stage disease requiring THA.