JOA - 2026-09-21 - Journal Article
Low Back Pain and Depression Are Associated with Worse Patient-Reported Outcomes After Primary Total Knee Arthroplasty.
Haji Boloori F, Kubiak A, Rezazadeh Shirazi A, Nelson B, Ciolacu I, Meyers M, Gaber K
Topics
Key Takeaway
Co-occurring low back pain and depression reduced odds of achieving MCID on Oxford Knee Score by 53% (OR=0.47) at 6 months post-primary TKA, with the greatest functional deficit concentrated in the lowest-improving quartile (25th-percentile β=-3.11).
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Summary
This registry-based study examined whether co-occurring low back pain and depression compound functional outcomes after primary TKA beyond either condition alone, using covariate-adjusted OKS change, MCID achievement, satisfaction, and quantile regression in 4,173 patients across four groups. All comorbid groups achieved lower adjusted mean OKS improvement than controls (Both β=-2.08, LBP β=-1.51, Depression β=-1.12), all below the 8-point MCID threshold, with the Both group having OR=0.47 for MCID achievement. Effects were additive rather than synergistic, and the functional disadvantage was concentrated in the lowest-improving quartile rather than distributed across the mean.
Key Limitation
Registry-based design precludes characterization of LBP severity, chronicity, or etiology and depression treatment status, preventing dose-response analysis or determination of whether optimizing either condition preoperatively modifies TKA outcomes.
Original Abstract
BACKGROUND
Low back pain and depression are common among total knee arthroplasty (TKA) candidates, and each predicts worse outcomes. Whether their co-occurrence adds beyond either condition alone has not been characterized at registry scale and mean-based analyses may obscure effects confined to the lowest-improving patients.
METHODS
We analyzed 4,173 patients who underwent primary TKA in a national arthroplasty registry. Patients were grouped as Neither (n = 2,261), low back pain only (LBP; n = 1,138), depression only (Dep; n = 394), and Both (n = 380). The primary outcome was covariate-adjusted six-month change in Oxford Knee Score (change in OKS). The secondary analyses included logistic regressions for the minimum clinically important difference (MCID; change in OKS ≥ 8), ordinal regressions for satisfaction, quantile regressions, and additive-interaction tests.
RESULTS
All three groups had lower adjusted mean change in OKS than Neither: LBP β = -1.51 (95% confidence interval (CI) -2.13 to -0.90), Dep β = -1.12 (-2.06 to -0.19), and Both β = -2.08 (-3.13 to -1.04), all below the eight-point MCID. Both had lower odds of achieving MCID (odds ratio [OR] = 0.47, 95% CI 0.32 to 0.68), as did LBP (OR = 0.54). Quantile regression localized the disadvantage to the lowest quartile (Both 25th-percentile β = -3.11). There was no interaction on either scale, indicating additive rather than synergistic effects. Low back pain independently reduced satisfaction (OR = 0.78, 95% CI 0.67 to 0.90). Readmissions and reoperations did not differ.
CONCLUSION
Co-occurring low back pain and depression were associated with small, but significant reductions in mean functional improvement and clinically meaningful reductions in MCID achievement concentrated in the lowest-improving patients. Effects appeared additive rather than synergistic. The findings support preoperative screening for both conditions and distributional, not only mean-based, outcome analysis in registry research.