Objective To evaluate biomeehanic characteristics of lumbar spondylolysis and spondylolisthesis single vertebrae reduction fixation system (LSRF), and discuss its mechanism of reduction. Method Twenty-four adult isthmus lumbar vertebrae specimen were disconnected and fixed with LSRF, Hefti, Salib's method respectively, and the biomechanic characteristics of the fixation devices were tested. Isthmus of L5 in 4 adult spine specimen was destroyed under loading to produce the spondylolisthesis model, and reduction by LSRF. Result The LSRF has a good ability for reduction and its strength for reduction is 1.6, 2.7 times as high compared with the Hefti, Salib's methods respectively. The mechanism of reduction is that the LSRF used contacted point of lamina by lamina hook as the fulcrum, through the pedicle screw to pull the spondylolisthetic vertebrae, and reduce the anterior displacement of vertebrae. Conclusion LSRF gives rigid fixation and good reduction, and provides a new and effective method for lumbar spondylolysis and isthmic spondylolisthesis.

Objective To conduct biomechanical study and three dimensional finite element analysis on lumbar spondylolysis and spondylolisthesis treated with single vertebra reduction and fixation system(LSRF), and to evaluate the long term outcome of isthmic spondylolisthesis treated with direct repair and fixation with LSRF. Methods Biomechanical characteristics of LSRF was tested, and three dimensional finite element model of lumbar spondylolysis and isthmic spondylolisthesis was established, the stress of lumbar in spondylolisthesis was observed after fixation and reduction. Thirty two patients with spondylolysis and isthmic spondylolisthesis were treated with direct repair and fixation with LSRF designed by the authors from 1992 to 1995. Eighteen cases had spondylolysis, and the others accompanied with spondylolisthesis. The patients age was 28-46 years, with an average of 36.4 years. Results The biomechanical study and three dimensional finite element analysis showed that LSRF has good ability in reduction and rigid fixation. All patients were followed up for an average of 5.6 years. The latest radiographs showed that bony union occurred in 29 cases. There was no breakage and pullout of screws except dislocation of hook in 2 patients. By Henderson standard, the result was excellent in 22, good in 6, fair in 2, poor in 2. Conclusion LSRF has stronger fixation strength and higher fusion rate. Direct repair and fixation with LSRF is a good procedure for younger and middle aged patients with spondylolysis and isthmic spondylolisthesis.

BACKGROUND:Whether lumbar spondylolisthesis needs to be treated with reduction remains controversial.OBJECTIVE:To investigate the clinical effectiveness of pedicle screw fixation combined with posterior lumbar interbody fusion for degenerative lumbar spondylolisthesis in the patients aged more than 70 years old.METHODS:The clinical data of 30 patients with degenerative spondylolisthesis aged over 70 years old undergoing pedicle screw fixation combined with posterior lumbar interbody fusion were analyzed retrospectively.The Visual Analogue Scale,Oswestry Dysfunction Index and the Japan Orthopedics Association scores were compared and analyzed before and after surgery.RESULTS AND CONCLUSION:(1) Among 30 patients,12 were male and 18 female,the average age was (75.1±6.7) years old,and all were followed up for more than 12 months.(2) The postoperative Visual Analogue Scale,Oswestry Dysfunction Index and the Japan Orthopedics Association scores were significantly improved compared with baseline (P ＜ 0.05).According to the Japan Orthopedics Association scores,3 cases were cured,24 were significantly effective,and 3 effective.(3) Graft fusion was achieved at all patients,the average fusion time was (5.13±0.65) months.(4) The average operation time was (225.6±23.4) minutes,the average intraoperative blood loss was (470±45.5) mL,and the average follow-up time was (25.8±3.5) months.(5) Six patients presented complications (20％),including one case of dural tear,two cases of paralytic intestinal obstruction,and three transient lower extremity nerve symptoms.(6) These results indicate that if the associated disorders are strictly controlled,pedicle screw fixation combined with posterior lumbar interbody fusion can achieve good surgical results in the treatment of degenerative spondylolisthesis in the elderly.

Degenerative disc disease (DDD) is a leading cause of low back pain, which severely affects the quality of life and incurs significant medical cost. Annulus fibrosus(AF) injuries can lead to substantial deterioration of intervertebral disc degeneration. However, the AF repair/regeneration remains a challenge due to the intrinsic cellular, biochemical and biomechanical heterogeneity of AF tissue. Tissue engineering would be a promising approach for AF regeneration. This article aims to provide a brief overview of the fundamental aspects of AF, the current achievements and future challenges of AF tissue engineering. A multidisciplinary approach is proposed for future studies to fully mimic the native AF tissue and its microenvironment, including choosing adequate cell source, preparing scaffolds with hierarchical microstructures, supplementing appropriate growth factors, and enforcing suitable mechanical stimulation. Hopefully, the engineered AF tissues would be effectively used to facilitate the treatment of DDD in the future.
Humans ; Intervertebral Disc ; growth & development ; Intervertebral Disc Degeneration ; therapy ; Regeneration ; Tissue Engineering

Objective To investigate the impact of various distribution of bone cement on the early clinical outcomes in osteoporotic vertebral compression fracture (OVCF) patients treated with percutaneous kyphoplasty (PKP).Methods A total of 312 patients (54 males and 258 females,mean age 69.37 years) who diagnosed as OVCF and received PKP treatment from January 2015 to July 2017 were enrolled in the present study.All subjects were divided into two groups according to different distribution of bone cement:the shaped "O" distribution (group O,113 cases),in which bone cement in the vertebral body presented whole crumb,no separation or loss of bone cement,and the shaped "H" distribution (group H,199 cases),in which bone cement in the vertebral body presented two briquettes,connected with or without a small amount of bone cement.Demographic data,surgical details,radiographic data,and clinical outcomes (at preoperatively,two-days and one-year follow-up) were compared between the two groups.Results There was no significant difference in bone mineral density (BMD),operation duration,blood loss,and occurrence of leakage of bone cement between two groups.In comparison with group O,group H was accompanied with higher volume of injected bone cement and higher proportion of bilateral approach (P＜0.05).Both groups achieved significant improvement of VAS scores after surgery,while the group H had a dramatical reduction of VAS scores at one-year follow-up compared with two-days follow-up (P＜0.05).In addition,group H had a better restoration of VAS scores at one-year follow-up than group O (P＜0.05),though no significant difference was observed at preoperative and two-days follow-up.Both groups achieved significant improvement of radiographic data after surgery (P＜0.05) with similar effects of correction.Conclusion Either shaped "H" or shaped"O" distribution of bone cement can obtain satisfied early clinical effects of PKP for the treatment of OVCF.Compared with shaped "O" distribution,shaped "H" distribution can achieve better pain relief at early follow-up.