Anterior reconstruction of spinal defect using nano-hydroxyapatite polyamide 66 cage for thoracolumbar tuberculosis: a long-term follow-up study

English Keywords:Spinal tuberculosis  Anterior approach  Nano-hydroxyapatite/polyamide 66

English Abstract:

  【Abstract】 Objectives: To evaluate the safety, reliability of n-HA/PA66 cage in the management of thoracolumbar tuberculosis after a long-term follow-up study. Methods: 18 patients with spinal tuberculosis, including 9 males and 9 females, were treated using debridement and strut graft with n-HA/PA66 cage combined with anterior instrumentations. The average age was 40.6±7.8 years (range, 18 to 63). The surgical levels included thoracic spine (T3-T10) in 8 cases, thoracolumbar spine (T11-L1) in 8 cases, and lumbar spine (L2-L4) in 2 cases. Kyphosis deformity presented in 13 patients with a Cobb angle of 31.0°±11.6°(range, 11° to 82°). According to ASIA grading system, neurological status was grade C in 4 patients, grade D in 9 and grade E in 5. Cold abscess formation, spinal canal involvement and sinus tract formation were found in 15, 13 and 2 patients respectively. Routine anterior debridement, inter-body strut graft and fixation with screw-rod system were applied. Anti-tuberculosis chemotherapy was continued for at least 18 months postoperatively. Results: All patients were successfully managed with this procedure. Except for 2 patients with pleural effusion post operation, no serious complications occurred. They were followed up for 7.5±1.8 years (range, 5 to 10 years). Except for one patient who had the preoperative ASIA grade improved from C to D, all other patients with neurologic deficit improved to normal at the last visit. The VAS score of back pain was relieved from 7.0±1.8 (range, 5 to 9) points to 2.4±0.6 (range, 0 to 3) points after surgery, an it was 1.4±0.4(range, 0 to 3) points at the final visit. The kyphosis was 31.0°±11.6° (range, 11° to 82°) before operation, and it was 18.2°±9.6° (range, 2° to 46°) immediately after operation with correction of 13.0°±8.3° (range, 10° to 36°). The kyphosis deteriorated to 22°±8.1° (range, 3° to 56°) at final follow-up with correction loss of 4.3°±0.8° (range, 1° to 11°). Bone fusion was achieved in 10 cases(56%) at 6 months after operation and in 17 cases (94%) at 1 year after operation. All cases achieved bony fusion in 2 years after operation. Delayed bone fusion was mainly noted in patients requiring 2 or more spinal motion segments reconstruction. In addition, 11 cases (61%) developed subsidence of cage mainly within 6 months after operation. The average subsidence was about 3.0±0.7mm(range, 0-6mm). One case of paravertebral abscess recurrence and sinus formation was noted and the patient was cured by the application of second-line anti-tuberculosis drugs, nutritional support and dressing change. Conclusions: According to middle to long term follow-up, N-HA/PA66 cagecan safely and effectively applied in the reconstruction of spinal stability following debridement of thoracolumbar tuberculosis.