The effect of Anti-NGF receptor (p75 Neurotrophin Receptor) antibodies on nociceptive behavior and activation of spinal microglia in the rat brachial plexus avulsion model.

STUDY DESIGN: We measured the response of the behavior and spinal glial activation to anti-nerve growth factor receptor (p75 neurotrophin receptor [p75NTR]) antibodies in the rat brachial plexus avulsion (BPA) model. OBJECTIVE: The aim of this study was to investigate the effect of anti-p75NTR antibodies on nociceptive behavior and activation of spinal microglia in the rat BPA model. SUMMARY OF BACKGROUND DATA: Tanezumab (anti-nerve growth factor antibody) treatment is associated with pain reduction and improvement in function, but with several complications. METHODS: Thirty male Wistar rats were used. In the BPA group, the C8-T1 roots were avulsed from the spinal cord with forceps at the lower trunk level and 10 µL of saline was applied locally (n = 10). In the anti-p75NTR group, the C8-T1 roots were avulsed and 10 µL of anti-p75NTR antibody was applied locally (n = 10). In a sham-operated group, the lower trunk was simply exposed (n = 10). Mechanical hyperalgesia and pain-induced walking patterns were measured using von Frey filaments (Stoelting, Wood Dale, IL) and the CatWalk gait analysis (Noldus Information Technology, the Netherlands) system every third day for 3 weeks. Activation of astrocytes and microglia was immunohistochemically examined in the spinal cord using anti-glial fibrillary acidic protein (GFAP) and anti-Iba1 antibodies both 7 and 21 days after surgery. RESULTS: Animals in the BPA group displayed significant mechanical hyperalgesia that continued through day 21 compared with animals in the sham-operated group, and mechanical hyperalgesia in the anti-p75NTR group was significantly improved 6 days after the operation. Regarding pain-induced gait analysis via CatWalk, animals in the BPA group displayed a significantly greater pain-like gait pattern than the p75 group for up to 3 weeks. Levels of GFAP-immunoreactive astrocytes and Iba1-immunoreactive microglia in the anti-p75NTR group were significantly reduced compared with the BPA group. CONCLUSION: Our results suggest that p75NTR contributes to neuropathic pain associated with BPA, and that inhibition of p75NTR reduces neuropathic pain. LEVEL OF EVIDENCE: N/A.

Surgical treatment of scoliosis using allograft bone from a regional bone bank.

INTRODUCTION: Routine spinal fusion techniques have involved removal of all soft tissues and articular facets, decortication of all posterior elements, and application of bone graft to the fusion area. Bone grafting has been performed mainly using the patient's own bone (autograft bone), most commonly from the iliac crest. The use of autograft bone is accompanied by complications or problems because of harvesting and donor-site morbidity. Several studies have already reported the use of allograft bone in scoliosis surgery. However, these studies are small series with short-term follow-up. METHOD: Twenty-two patients with scoliosis who underwent posterior spinal fusion and pedicle-screw-alone fixation using banked allograft bone obtained from the regional bone bank in Japan were analyzed. The average age at surgery was 13 years 5 months. The average follow-up was 2 years 7 months, and the average age at the last follow-up was 15 years 6 months. Scoliosis curves were divided into two groups (single curve group and double curve group). RESULTS: For the single curve group, the average preoperative coronal curve measured 78° (48°-85°) and the postoperative curve measured 22° (8°-35°), with no loss of correction at the last follow-up. For the double curve group, the average preoperative thoracic curve measured 64° (48°-85°) and the lumbar curve measured 42° (38°-60°). The average postoperative thoracic curve measured 12° (8°-34°) and lumbar curve measured 15° (8°-32°), with no significant loss of correction at the last follow-up. No patients had clinical complaints in the region of surgery at 9 months after surgery and thereafter. There were no complications including loss of correction, nonunion, infection and instrumentation failure. At the last follow-up, patients/parents were interviewed and asked to complete an outcome satisfaction questionnaire. They were asked to rate the outcome as very satisfactory, satisfactory, neither satisfactory nor unsatisfactory, unsatisfactory, or very unsatisfactory. Seventeen patients (77%) were very satisfied, four patients (17%) were satisfied, and one patient (6%) was neither satisfied nor unsatisfied. Autograft bone and banked allograft bone appear to yield comparable results and clinical outcomes. CONCLUSION: However, in Japan, various expenses accrue to supply a safe and premium quality of banked allograft bone. Financial issue must be resolved as soon as possible.