Two-level lumbar total disc replacement: Functional outcomes and segmental motion after 4 years

IntroductionLumbar total disc replacement is an effective treatment for single-level discogenic lower back pain. But the replacement of two disc levels is controversial.HypothesisTwo-level total disc replacement will improve function while preserving spinal motion.Material and methodsA continuous series of 108 patients (51 women, 57 men) surgically treated over two levels with the ProDisc-L implant (Synthes Spine) was evaluated retrospectively with an average follow-up of 4 years. Ninety-three of these patients were operated for L4/L5 and L5/S1 degenerative disc disease, while 15 were operated for L3/L4 and L4/L5 disease. The procedure was carried out through the left retroperitoneal approach in 65 patients, the right retroperitoneal approach in 42 patients and both approaches in 1 patient. The Oswestry score, lumbar VAS and radicular VAS were used to evaluate function. The motion of the prosthetic disc segments was evaluated using Cobb's method. Data were collected prospectively in the context of regular patient monitoring. A retrospective analysis was carried out by an independent examiner.ResultsThe procedure led to a statistically significant improvement in the functional scores. The motion of the upper disc segment was 9° (0°–19°) in flexion/extension and 5.5° (2°–12°) in lateral bending. It was 6.2° (0°–14°) and 1.9° (0°–7°) at the lower disc segment. The range of motion was similar in L3/L4 and L4/L5, but was less in L5/S1. Lack of mobility was not correlated with alterations in the functional outcome. The complication rate was 18%.DiscussionTwo-level lumbar disc replacement improves spinal function while preserving its mobility. But this procedure is fraught with risks and must be carried out by a highly-experienced team. A longer follow-up is needed to evaluate the sustainability of the results and to detect any adjacent segment disease. The French National Authority for Health (HAS) has recommended against two-level lumbar disc replacement, so it no longer can be performed in France.