Objective To investigate the influential factors for refracture of the adjacent vertebral body following percutaneous vertebroplasty (PVP) treatment of patients with osteoporotic vertebral compression fractures (OVCFs).Methods A retrospective analysis was conducted on OVCFs patients undergone mono-segmental PVP from July 2007 to March 2010.Patients' age,gender,bone density,bone cement infusion dosage,bone cement leakage and pre-and post-operative fracture reduction were documented.Kaplan-Meier remaining rate curve was used to predict the trend of time to refracture.The related factors for adjacent vertebral body refracture following PVP were analyzed.Results In all,216 patients (98 males and 118 females; age range of 55-76 years,average 65.4 years) were enrolled in this study.Follow-up lasted for 12-18 months.Ninety-two patients sustained refracture including 68 patients with refracture of the adjacent vertebral body.Refracture of the adjacent vertebral body presented time-concentrated tendency and 66％ (45/68) occurred within 100 days followed by a notably lower incidence.Whereas the time to refracture of the non-adjacent vertebral body was not obviously centralized.Bone cement infusion dosage and vertebral body reset condition were strongly associated with the refracture incidence of the adjacent vertebral body,while opposite results were observed in regard of age,gender,bone density and bone cement leakage (or not).Conclusion PVP predisposes OVCFs patients to refracture of the adjacent vertebral body and its influential factors may be associated with bone cement infusion dosage and vertebral body reduction condition.

ObjectiveTo investigate the clinical effects of posterior atlantoaxial fusion fixation in treatment of old atlantoaxial injury secondary to atlantoaxial dislocation.MethodsA retrospective analysis was carried out on 16 patients ( 14 males and 2 females) with old atlantoaxial injuries secondary to atlantoaxial dislocations managed with posterior atlantoaxial fusion fixation from March 2008 to March 2012.The time from injury to operation lasted for 3-36 months ( average 10.5 months).Posterior atlantoaxial transpedicular fixation was performed in 13 patients including 10 patients with old odontoid fractures and three with old traumatic transverse ligament disruptions of the atlas combined with atlantoaxial dislocations.Also,posterior atlantal arch transpediclar fixation combined with axial pedicle screw fixation was performed in three patients who had old odontoid fractures combined with atlantoaxial dislocations.All patients had simultaneous autogenous bone grafting between atlas and axis during reduction and fixation.The preoperative and postoperative Japanese Orthopaedic Association (JOA) scores were compared.Follow-up X-ray films and CT was performed to evaluate the atlantoaxial reduction and fusion.ResultsAll the patients were followed up for 9-18 months ( mean 13 months).None of the patients had spinal cord or vertebral artery injuries.Follow-up CT showed that two patients had partial penetration of one side axial pedicle screws into transverse foramen without nerve and blood vessel injuries.Clinical symptoms obtained different degree of improvement.The postoperative JOA scores ranged from 13 to 16 points ( mean 14.8 points) and the improvement rate of JOA was 71％-92％ ( mean 82％ ).The X-ray films and CT showed sound bone fusion,with good location of screws but with no signs of atlantoaxial instability or loss of reduction,or loosening or breakage of the screws.ConclusionPosterior atlantoaxial fusion fixation can effectively reconstruct atlantoaxial stability,improves neurologic function of spinal cord and has reliable curative effects.