Clinical and Radiological Comparison of Semirigid (WavefleX) and Rigid System for the Lumbar Spine

OBJECTIVE Spinal fusion operation is an effective treatment in the spinal pathology, but it could change the physiological distribution of load at the instrumented and adjacent segments. This retrospective study compared the radiological and clinical outcomes of patients undergoing lumbar fusion with semirigid rods versus rigid rods system. METHODS Using transpedicular fixation and posterior lumbar interbody fusion at the level of L4/L5, 20 patients were treated with semirigid rods (WavefleX, SR group), and 20 patients with rigid rods (titanium, RR group). Clinical and radiological outcomes were evaluated, including visual analog score for lower back pain and leg pain, Prolo functional and economic scores, statues of implanted instruments, fusion rate, and complications during 24-month follow-up. RESULTS Clinical scores were significantly improved until postoperative 24-month follow-up as compared with preoperative scores in both groups (p<0.05), with similar levels of improvement observed at the same time points postoperatively between the 2 groups. Prolo economic scores were significantly improved in SR group compared to RR until 12 months, but this improvement became similar after 18 months. The overall fusion rate was 94.1% until the 24-month follow-up for both groups. No significant complication was observed in both groups. CONCLUSION The results of the present study indicate that semirigid rods system with posterior lumbar interbody fusion showed similar clinical and radiological result with rigid rods system until 2 years after instrumentation. The WavefleX rods system, as a semirigid rods with unique characteristics, may be an effective alternative treatment for patients in lumbar fusion.