Prospective Study of Lumbar Spondylolisthesis Treated with Posterior Lumbar Total Joint Replacement: Clinical Results from an Investigational Device Exemption Trial

Introduction: Posterior lumbar total joint replacement (TJR) is a spinal arthroplasty procedure that uses a posterior bilateral transforaminal approach and involves implantation of a novel motion-preserving device that functions biomechanically as a new articulation for the resected disc and facets.

Methods: We present the minimum 1-year clinical results of a prospective, protocol-specified Investigation Device Exemption (IDE) trial. The propensity score matched trial evaluates the safety and effectiveness of TJR compared to TLIF in the treatment of patients with symptomatic lumbar spondylolisthesis.
Patient related outcome measures included 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: The IDE trial compared 67 TJR participants and 126 TLIF weighted matched controls with 12 months follow-up.
There were 71% and 61% decreases 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 statistically significant (p=0.03). The corresponding effect size was 0.50 reflecting a medium effect. The 12-month between-groups differences in ODI (94% vs 87%), VAS back (85% vs 86%) and worst leg pain (87% vs 93%) responder rates were not statistically significant (p>0.20 for all comparisons).

Conclusion : Back function and pain improved in both groups; but patients treated with the posterior lumbar arthroplasty (TJR) showed statistically significantly greater ODI improvement (71% ODI decrease) compared to TLIF (61% ODI decrease). These results indicate that surgical treatment of spondylolisthesis with a motion-preserving posterior lumbar TJR device is safe and efficacious.