OBJECTIVETo investigate the early clinical effects and radiological outcome of dynamic cervical implant (DCI) internal fixation in treating cervical spondylosis, and evaluate its safety and efficiency.

METHODSFrom June 2009 to December 2011, 19 patients with cervical spondylosis correspond to the indication of DCI internal fixation in the study, including 5 cases of cervical spondylotic myelopathy and 14 cases of cervical spondylotic radiculopathy. There were 8 males and 11 females, aged from 35 to 54 years with a mean of 43.2 years. Pathological segments included C3,4 in 1 case, C4,5 in 6, C5,6 in 6, C6,7 in 4, C3,4 and C5,6, C6,7 in 2. All patients were treated with anterior discectomy and decompression and DCI internal fixation, meanwhile, 2 cases of them with anterior cervical corpectomy and fusion plate fixation. Clinical evaluation included Modified Japanese orthopedics association (mJOA), neck disability index (NDI), visual analogue scale (VAS) score and patient satisfaction index (PSI) at pre-operation and final follow-up. Radiographic evaluation included flexion/extension lateral view at operative level and adjacent segment. The adjacent level degeneration was analyzed according to Miyazaki classification on MRI images.

RESULTSAll patients were followed up from 12 to 42 months with an average of 19.8 months. Preoperative mJOA score was 13.6±1.1 and at final follow-up was 16.3±1.2 with improvement rate of 85.0%. Preoperative VAS,NDI was 6.6± 1.4, 17.1±7.4 and at final follow-up was 1.4±0.8, 6.1±3.9, respectively; there was statistical significance in all above-mentioned results between preoperative and final follow-up (P<0.05). Preoperative ROM at operation level was (7.6±1.9)° and final follow-up was (7.8+2.1)°; preoperative ROM at C2-C7 was (38.6±7.2)° and final follow-up was (39.9±6.4)°; there was no statistical significance in all above-mentioned results between preoperative and final follow-up (P>0.05). Preoperative DHI at operation level was (6.3±1.1) mm and final follow-up was (7.1±0.8) mm, there was statistical significance in DHI between preoperative and final follow-up (P<0.05). No heterotopic ossification was found. All patients followed up MRI, degeneration of 3 segments aggravated 1 degree in 38 adjacent segments, without clinical symptom.

CONCLUSIONTreatment of cervical spondylosis with dynamic cervical implant can got satisfactory outcome in early follow-up. Activity of operative segment obtain reservation in some degree. The incidence of adjacent segment degeneration is lower and no adjacent segment disease occur. Nevertheless a longer follow-up time should be needed to assess the long term functionality of the DCI and the influence on adjacent levels.