Neurosurgeon Hospital for Special Surgery Philadelphia, PA, US
Introduction: Lumbar total joint replacement (TJR) is a motion segment reconstruction procedure that uses a posterior bilateral transforaminal approach and involves implantation of a device that functions biomechanically as a new articulation for the resected disc and facets. A propensity score matched multi-site pivotal US trial is underway at 20 US sites to determine the safety and effectiveness of TJR compared to TLIF in the treatment of patients with symptomatic lumbar degeneration.
Methods: This was a planned initial analysis that included 67 TJR participants and 126 TLIF weighted matched controls with 12 months follow-up. Back function was evaluated using the Oswestry Disability Index (ODI) and back and worst leg pain severity by visual analog scale (VAS). 12-month responder rates were based on a minimal clinically important difference (MCID) of ≥ 15-points for ODI and ≥ 20 mm for VAS compared to baseline. Cohen’s between-group effect size for change from baseline was computed.
Results: There were no statistically significant baseline differences between groups in mean age (50.5 vs 53.8 yrs), BMI (28.4 vs 28.4 kg/m2), ODI (64.4 vs 62.1), VAS back (74.3 vs 73.6 mm) or worst leg (71.7 vs 76.8 mm). There was a 71% and 61% decrease in ODI at 12-months for TJR and TLIF, respectively, and the average between-group difference (7.8, 95% CI [0.9, 14.6]) was significant (p=0.03). The corresponding effect size was 0.50 reflecting a medium effect. 12-month ODI (94% vs 87%), VAS back (85% vs 86%) and leg (87% vs 93%) responder rate differences were not statistically significant between groups (p>0.20 for all comparisons).
Conclusion : Substantial improvements in back function and pain were realized in both groups; however, even at this interval analysis, with 42% (TJR) and 86% (TLIF) patients with 12-month follow-up, improvement in ODI significantly favored patients treated with TJR.
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