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Is Dynesys a Good Device for Motion Preservation and Prevention of Idiopathic Unstable after Decompression Surgery

Introduction The Dynesys dynamic stabilization system was first implanted in patients in 1994 in an attempt to overcome the drawbacks of fusion. It is supposed to preserve motion at the treat levels, while avoiding hypermobility and thus spondylosis at the adjacent levels. The aim of this retrospective study is to investigate the clinical outcome and the effect of preservation of ROM and developed instability after decompression surgery. Patients and Methods A total of 30 patients were treated with Dynesys between August 2008 to March 2014. The diagnosis included degenerative spinal stenosis, severe spinal stenosis with HIVD, huge intervertebral herniated disc, or recurrent HIVD. Back pain and leg pain were evaluated using visual analog scale (VAS). The Oswestry Disability Index (ODI) was used to evaluate the patient's function. The range of motion at the operative level and whole lumbar spine were measured on preoperative and postoperative radiographs. Results All the patients were followed up for 3 to 96 months (mean, 26.33 ± 25.3 months). Overall, 87 segments were applied in 30 patients. The mean age of the patients was 49.5 ± 10.4 years (range, 22–67 years). There were 19 male and 11 female patients, with slightly male predominant. VAS of leg pain, lower back pain, and the ODI were significantly improved postoperatively. There was a significant difference in the range of motion at the operative levels and the whole spine. The mean range of motion of whole spine was 28.89 ± 15.3 degrees preoperatively and 16.29 ± 8.39 degrees postoperatively, with 43.61% loss. The range of motion of operative levels were 12.01 ± 7.73 degrees preoperatively and 4.03 ± 3.19 degrees postoperatively, with 66.44% loss. There were four broken screws and no screws loosening were noted. No developed unstable conditions occurred and no cases need revision surgery in our study. Conclusion The preliminary results of Dynesys for lumbar degenerative stenosis with/without HIVD in our series are similar to the published results of the previous literature. It can significantly improve the clinic symptoms and signs. And the Dynesys device is a semirigid fixation system for the stabilization of lumbar degenerative disease. We think the role of Dynesys is a device to delay the nature decade of lumbar spine and prevent the possibility of idiopathic unstable after decompression surgery. So, the indication of the Dynesys should seriously restriction of the age. It should be used in the patients with no or mild unstable condition, and it is better in the younger patients. But the true effect should depend on longer follow-up.