Objective To evaluate the incidence of heterotopic ossification (HO) after single-level Bryan cervical artificial disc replacement, and to identify the relationship between HO and the effectiveness. Methods The cl inical data of 48 patients undergoing single-level Bryan cervical artificial disc replacement between October 2005 and October 2007 were reviewedretrospectively. There were 27 males and 21 females with an average age of 40.5 years (range, 33-51 years), including 8 cases of cervical myelopathy, 27 cases of nerve root cervical spondylosis, and 13 cases of mixed cervical spondylosis with an average disease duration of 10.3 months (range, 2-14 months). The involved segments included C3, 4 in 3 cases, C4, 5 in 6 cases, C5, 6 in 30 cases, and C6, 7 in 9 cases. The outcomes were evaluated using Visual Analogue Scale (VAS) score, the neck disabil ity index (NDI), and cervical range of motion (ROM). According to patients with or without HO, 48 patients were divided into 2 groups (HO group and no HO group). VAS score, NDI, and cervical ROM were compared between 2 groups at 1, 2, 3, and 4 years after operation. Results No severe complication occurred during and after operation in all patients. Forty-eight patients were followed up 48-72 months (mean, 56.6 months). VAS score and NDI were significantly improved when compared with preoperative values at all time points (P lt; 0.05); except at 3 days after operation, no significant difference was found in cervical ROM at the other time points when compared with preoperation (P gt; 0.05). Thirteen patients (27.08%) had HO at 4 years after operation, including 8 cases of grade 1, 3 cases of grade 2, and 2 cases of grade 3. There was no significant difference in VAS score, NDI, and cervical ROM between 2 groups at 1, 2, 3, and 4 years (P gt; 0.05). Conclusion The incidence of HO after single-level Bryan cervical artificial disc replacement is relatively high. However, HO has no effect on the cervical ROM and the effectiveness.
Objective To evaluate the cl inical outcomes and values of anterior segmental decompression and double-plate fixation (ASDDF) for treatment of ski p cervical spondylotic myelopathy (SCSM). Methods Between June 2005 and June 2008, 17 patients with SCSM were treated with ASDDF. There were 10 males and 7 females with an average age of 58.8 years (range, 41-74 years) and an average disease duration of 9.7 months (range, 6-39 months). According to JapaneseOrthopaedic Association (JOA) score system, 2 patients were rated as extreme severe condition, 7 as severe, 7 as moderate, and 1 as mild. MRI images showed 42 affected cervical disc levels, including 26 disc levels with high-intensity intramedullary lesions on T2, 4 with low-intensity intramedullary lesions on T1, and 12 with significant cord compression but no signal change; according to Nagata classification scale, there were 5 abnormal segments at class I, 21 at class II, and 16 at class III. The rate of fusion, the Cobb angle, and the range of motion (ROM) of the cervical spine were measured preoperatively and postoperatively by the X-ray examinations. The improvement of the neurological function was evaluated by the JOA score. Results The average time of follow-up was 28.6 months (range, 24-58 months). After operation, dysphagia occurred in 2 cases (symptom rel ief after 1 month), hoarseness in 1 case (symptom rel ief after 3 months of methylcobalamin treatment), and degeneration of adjacent segments without symptom in 3 cases. The X-ray films showed the fusion rate of 100% at 12 months after operation without displacement, resorption or collapse of bone graft, and without breakage or loosening of plate and screw. The Cobb angles were (13.3 ± 10.4)° preoperatively, (15.8 ± 10.8)° immediately postoperatively, and (15.4 ± 11.4)° at last follow-up; the ROM of the cervical spine were (41.3 ± 17.4)° preoperatively and (23.8 ± 18.8)° at last follow-up; and the JOA scores were 8.2 ± 2.9 preoperatively, 13.7 ± 3.0 at 12 months postoperatively, and 13.9 ± 2.8 at last follow-up. All indexes showed significant differences between before operation and after operation (P lt; 0.05). The results of JOA scores were excellent in 8 cases, good in 6, fair in 2, and poor in 1 with an average improvement rate of 66.8% (range, 14%-88%) for the neurological function. Conclusion Adequate decompression, high rate of fusion, sol id mechanical stabil ity, improvement of total cervical lordosis,and the neurological function can be achieved through ASDDF for treatment of SCSM.