Correlation of Clinical Outcome and Radiological Parameters for Activ L Total Disc Replacement

Abstract

Introduction Summary of Background Data Radiological results are important parameters for total disc replacement (TDR) patients, but the correlation of various radiological parameters with clinical results is still controversial. Study design A prospective clinical study. Purpose To assess the clinical and radiological results for patients who underwent Activ L total disc replacement, and to correlate various radiological parameters with clinical outcome. Materials and Methods From March 2009 to March 2012, 32 patients with degenerative disc diseases (DDD) underwent either mono- or bi-segmental lumbar TDR, of whom 30 (93.7%) with 36 prosthesis had an average follow-up of 28.8 months (12-46 months). Clinical parameters such as Visual Analogue Scale (VAS), and Oswestry Disability Index (ODI) were evaluated preoperatively and at 1, 2, and 3 years postoperatively. Radiological parameters as range of motion (ROM), intervertebral disc height (IDH) of the index and adjacent segments, coronal and sagittal positions of the prosthesis, and lumbar lordosis were also performed. Prosthesis subsidence and heterotopic ossification were observed during the follow-up period. Results Thirty patients had 1 year follow-up, 20 of whom had 2 years follow-up and 15 of whom had 3 years follow-up. The VAS (back pain), VAS (leg pain), and ODI score showed significant improvement after surgery ( p < 0.001), and there was no significant difference between each follow-up ( p > 0.8754). At the 3-year follow-up, ROM of the index level and the upper adjacent level showed significant increase ( p < 0.0128), while the lower adjacent level showed no obvious increase of ROM ( p = 0.4205). Immediately after surgery, IDH of the index level showed a significant increase ( p < 0.0071), but the difference disappeared at the 3-year follow-up ( p = 0.0597). The IDH of the upper and lower adjacent level showed no significant difference during the 3-year follow-up ( p > 0.6669). Compared with preoperative data, the lumbar lordosis showed no obvious difference during the 3-year follow-up ( p = 0.2643). According to one of the radiological criteria, 75% of the prostheses were rated as ideally positioned, 16.7% were discretely shifted, 5.6% were slightly shifted, and 2.7% were markedly shifted in the coronal plane. In the sagittal plane, 13.9% of the prostheses were rated as ideally positioned, 22.2% were discretely shifted, and 63.9% were suboptimally placed. At each patient's final follow-up, the radiological parameters did not correlate with clinical results ( p < 0.001). Conclusion The short- and mid-term results of Activ L prosthesis for degenerative disc diseases are satisfying. Our data indicate poor correlation between various radiological parameters and clinical outcome. Disclosure of Interest None declared