# Association between severe lumbar disc degeneration and end-stage hip or knee osteoarthritis requiring joint replacement surgery: a population-based cohort study with a 26-year follow-up

## TL;DR

This study finds a strong link between severe spinal disc degeneration and hip osteoarthritis requiring surgery, but a weaker link with knee osteoarthritis.

## Contribution

The study provides new evidence from a large population-based cohort with MRI data and 26-year follow-up on the association between lumbar disc degeneration and joint replacement surgery.

## Key findings

- Severe lumbar disc degeneration at multiple levels is strongly associated with increased risk of hip replacement surgery.
- The association between lumbar disc degeneration and knee replacement surgery is weaker and not statistically significant after adjustment.
- Higher BMI increases the risk of both hip and knee replacement surgeries, with a stronger effect on knees.

## Abstract

An association between intervertebral disc degeneration (IDD) and osteoarthritis (OA) of the hip and knee has been found previously. However, studies using MRI-evaluated IDD grades with large sample sizes are lacking. Total hip and knee arthroplasty (THA and TKA) can be considered an indicator of clinically evident end-stage OA.

The study population consisted of 1,153 postmenopausal Finnish women with clinical back problems, of whom 166 had THA and 295 had TKA during the 26-year follow-up. The study was based on the prospective OSTPRE cohort established in 1989 and Finnish Arthroplasty Register data. The IDD severity was graded from T2-weighted lumbar MRI images using the five-grade Pfirrmann classification. Five intervertebral levels (L1-L2 to L5-S1) were studied (5,765 discs). Cox regression with a time-dependent covariate was used to calculate hazard ratios (HRs) for THA and TKA to account for exposure time for severe degeneration.

A higher hazard for THA was observed in women with severe IDD at the L1-L2 (HR 2.66, 95% CI 1.48–4.80), L2-L3 (HR 1.97, CI 1.15–3.38), L5-S1 (HR 1.69, 95% CI 1.16–2.46) and the L1-S1 (HR 2.19, 95% CI 1.53–3.15) intervertebral levels. Adjustment with potential confounders did not alter the results. Women with severe IDD had an elevated hazard for TKA at the L1-S1 mean degeneration (HR 1.50, CI 1.11–2.02) analysis. However, in the adjusted model, the statistical significance of this association was lost (HR 1.34, 95% CI 0.98–1.84). Higher BMI increased the hazard for both THA and TKA; however, the effect was more substantial for TKA.

The present study supports the association between lumbar IDD and hip OA. A weak association between lumbar IDD and knee OA was observed. Further research is needed to investigate the causality of the relationship between IDD and OA.

The online version contains supplementary material available at 10.1007/s00402-025-05908-7.