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The primary object of this investigation was to study recombinant human bone morphogenetic protein-2 (rhBMP-2)-induced ossification of the ligamentum flavum and associated histone H3 modification in a rat model. In an additional set of studies the authors investigated spinal cord and behavioral changes in the same model.The authors report on 2 separate sets of studies. A total of 90 rats were used for the 2 sets of studies (45 each); in each study, a lyophilized rhBMP-2 and collagen mixture (20 μg rhBMP-2 and 200 μl collagen) was implanted in the lumbar extradural space in 18 rats; another 18 animals were used for a sham-operation control group and underwent implantation of lyophilized collagen without rhBMP-2 at the same level; an additional 9 animals were used as untreated controls. Lumbar spinal samples were harvested from the rhBMP-2 groups and the shamoperation control groups at 1 week, 3 weeks, and 9 weeks after the operation. Samples were also obtained from untreated controls at the same time points. All samples were scanned using micro-CT and then made into paraffinembedded sections. The sections from the first set of 45 rats were stained using elastica van Gieson and toluidine blue, and the expression of histone modifications (H3K9ac, H3K18ac, H3K4me3, and H3K36me3) and osteogenic transcription factors (osterix, Runx2) was detected by immunohistochemistry. In the second set of studies, hindlimb motor function was assessed at 1 week, 3 weeks, and 9 weeks after surgery. After behavioral evaluation, samples were harvested, scanned using micro-CT, and then made into paraffin-embedded sections. The sections were stained using Luxol fast blue. The expression of NeuN was also detected using immunohistochemistry.Ossification was seen in the rhBMP-2 group from 1 week after insertion, and the volume of ossified mass increased at 3 and 9 weeks. There was no ossification seen in the sham-surgery and normal controls. The pathological changes of ossification involved ligament degeneration, cartilage formation, and, finally, bone replacement. Spinal cord evaluation showed a significant decrease in white matter content and number of neurons at 9 weeks after operation in the rhBMP-2-treated group (compared with findings in the sham-surgery and control groups as well as findings at the earlier time points in the rhBMP-2 group). Using immunohistochemical staining, histone modifications (H3K9ac, H3K18ac, H3K4me3, and H3K36me3) and osteogenic transcription factors (osterix, Runx2) all were found to be expressed in the fibrocartilage area of the rat ossified ligamentum flavum samples (rhBMP2 group).This rhBMP-2-induced OLF is a typical endochondral ossification, which is similar to clinical OLF. The compressed spinal cord around the ossification site showed signs of a chronic degenerative process. Histone H3 modifications (H3K9ac, H3K18ac, H3K4me3, and H3K36me3) may play an important role in OLF.

To investigate the long-term surgical outcome of thoracic myelopathy caused by the ossification of the ligamentum flavum (OLF) and evaluate the related risk factors.Forty-four patients who underwent decompressive laminectomy with thoracic OLF between January 1990 and December 2005 and got more than 5 years follow-up were retrospectively reviewed. Among these 44 cases, there were 29 male and 15 female whose ages at operation were 52 years averagely (27-68 years). The 2-year follow-up results and long-term outcomes were classified according to the modified Epstein's standard, and then the rates of excellent or good (REG) were calculated. The correlation between the long-term REG and the patients' ages, durations of symptoms, decompressed levels, and dural leak were analyzed.The mean follow-up period of these 44 cases was 8.5 years (5-19 years). The REG at 2 years after laminectomy was 77.3% (34/44), while the long-term REG was 65.9% (29/44). There was one case who had suffered from an acute spinal cord injury got a poor post-operative outcome. The other 43 cases had chronic durations, including 22 cases whose pre-operative durations of symptoms were less than 12 months and 21 cases whose durations were equal to or more than 12 months. And the long-term REG of these two groups were 77.3% (17/22) and 57.1% (12/21) respectively (P0.05). The REG of those cases whose decompression levels were limited in T1-T9 was 78.9% (15/19), while that of those cases whose laminectomy was relevant to thoracolumbar segment (T10-L2) was 58.3% (14/24) (P0.05). There were 7 cases who had excellent or good short-term results and poor long-term outcomes. The reasons of these changes included coexistence of lumbar spinal stenosis in three cases and the growth of the OLF at the adjacent levels in four cases.Although the short-term results of the decompressive surgery for thoracic OLF is good, the regular long-term follow-up is necessary because the symptoms may reoccur or deteriorate secondary to lumbar spinal stenosis or the growth of OLF at the adjacent levels near former decompressive levels; the duration of symptoms which is more than one year and the decompression levels that is involved to T10-L2 segments are possibly related to the poor long-term outcomes.

To observe the results of posterior osteotomy and correction in the surgical treatment of old tuberculous kyphosis.From June 2004 to December 2008, 31 cases of old tuberculous kyphosis with posterior osteotomy and correction technique were treated. There were 12 cases of male and 19 cases of female. The average age was 33.4 years. Pedicle subtraction osteotomy or vertebral column resection were applied in surgery. The kyphosis angle, lumbar lordosis angle and sagittal balance condition of the spine were measured before and after surgery, as well as follow-up. The Frankel grading system for neurological function of lower extremities, the Oswestry disability index (ODI) for life quality, and patient satisfactory index (PSI) for satisfaction of surgery were applied before surgery and at follow-up.The average kyphosis angle was 94° ± 27°, the average lumbar lordosis angle was 71° ± 20°, and the average sagittal C(7) plumb line was (-15 ± 44) mm away from the balance region before surgery. The average kyphosis angle decreased to 26° ± 11° in one week after surgery, with an improvement rate of 71.4%. The average follow-up time was 22.5 months. The average kyphosis angle was 28° ± 12° at the final follow-up, with an improvement rate of 70.0%. The average lumbar lordosis angle was 46° ± 11°, with an improvement rate of 35.1%. The postoperative kyphosis angle and lumbar lordosis angle were significantly different with that of pre-operation (for kyphosis angle: t = 16.3, P0.05; for lumbar lordosis angle: t = 8.1, P0.05). The average sagittal C(7) plumb line was (-4 ± 22) mm away from the balance region at the final follow-up, with an improvement rate of 73.4%. The Frankel grading were E in 13 cases, D in 13 cases, and C in 5 cases before surgery, and were E in 20 cases, D in 8 cases, and C in 3 cases at the final follow-up. The average ODI was 13 ± 12 before surgery, and was 7 ± 8 at the final follow-up, with an improvement rate of 45.2%. The PSI results showed a satisfied rate of 90.3%.Good results can be achieved by applying proper posterior osteotomy and correction technique according to the severity of old tuberculous kyphosis.

Various surgical approaches have been successfully used in the treatment of thoracolumbar disc herniation (TLDH). Although the anterior transthoracic approach has a reputation for better visualization than the posterolateral and lateral approaches, it involves the manipulation of the thoracic and pulmonary structures. Thus, this approach is technically demanding and prone to compromising the respiratory system. An ideal approach would involve adequate visualization and be accomplished through the posterior midline approach that is familiar to spine surgeons. The objective of this retrospective preliminary clinical study was to introduce a new surgical procedure, circumspinal decompression through a single posterior incision, for the treatment of TLDH (T10/11-L1/2) and to evaluate the surgical outcome of this procedure by comparing it to the conventional anterior transthoracic approach.In this study, 15 patients (10 males, 5 females; mean age 51 years) with symptomatic TLDH underwent the circumspinal decompression through a single posterior incision procedure between January 2008 and December 2009. Altogether, 17 herniated discs were excised, with 2 discs at T10/11, 4 discs at T11/12, 5 discs at T12/L1 and 6 discs at L1/2. Of these patients, 13 were followed up with a mean follow-up period of 23.5 months. Clinical outcomes, including operative time, blood loss, perioperative complications, postoperative time of hospitalization, neurologic status improvement, back pain and correction of local kyphosis, were investigated by comparing these data with the results from patients who underwent the anterior transthoracic approach for TLDH during the same period. The patients' neurologic status was evaluated by a modified Japanese Orthopedic Association (JOA) scoring system of 11 points. Neurologic status improvement after the surgery was assessed by calculating the recovery rate, which was equal to the (postoperative JOA score-preoperative JOA score)/(11-preoperative JOA score)×100%. The rates of patients who improved at the final follow-up were also assessed.The mean operative time was 183 minutes, the mean blood loss was 1067 ml, and the mean postoperative hospitalization time was 8.4 days. Three patients suffered perioperative complications, but none of these complications involved the respiratory system. Local kyphotic angles at the fusion levels were reduced. Of the 13 patients that were followed up, 12 improved at the final follow-up, with a mean recovery rate of 52.8%. Patients who underwent the circumspinal decompression procedure showed a higher percentage of improvement at the final follow-up, a higher degree of local kyphosis correction and a lower percentage of complications (especially respiratory complications) compared to patients who underwent the anterior transthoracic decompression procedure.The circumspinal decompression through a single posterior incision procedure is an effective and safe technique that is comparable to anterior tranthoracic approach for the surgical treatment of TLDH patients. It could be an attractive choice in certain circumstances.

To analyze the impact of thoracic and thoracolumbar angular kyphosis on pelvic shape and sagittal alignment.From May 2002 to June 2010, the sagittal spino-pelvic parameters were analyzed in lateral standing radiographs of 32 patients (mean age 29.6 years) with thoracolumbar angular kyphosis. The parameters included Cobb angle of kyphosis, lumbar lordosis (LL), pelvic incidence (PI), sacrum slope (SS), pelvic tilt (PT) and sagittal vertical axis (SVA). All pelvic parameters in the patients were compared with those reported in historical normal subjects. All patients were treated by using kyphotic correction and fusion. The preoperative and postoperative parameters were compared. The pelvic parameters were also compared between the patients with kyphotic apex located at T(1-8) and those located at T(9-12) and thoracolumbar junction. The linear regression analysis was used to investigate the independent factors of PI.The mean kyphosis was 90.1° (31° - 138°). The mean age of kyphosis occurrence was 6.1 years. The mean PI, SS and PT were 34.8°, 35.8° and -0.7° respectively. The PI and PT were significantly smaller (P0.001) in the patients than those in normal subjects while the SS was similar. The kyphosis was improved to 27.9° post-operatively. There was no difference in PI values between pre-operation and postoperation (P0.05). The PI and SS in patients whose kyphosis located at thoracic spine (T(1-8)) were significantly higher than those at T(9)-L(2). Instead of patients' age and LL, the preoperative Cobb angle of kyphosis and the levels where kyphosis located were two independent impact factors of PI.The kyphosis occurred at childhood may influence pelvic shape and alignment significantly. The lower kyphotic apex located and the bigger kyphosis, the greater impact on the pelvic morphology. The surgery can improve the kyphosis, but can not change the sagittal pelvic morphology. Early treatment of thoracolumbar angular kyphosis is beneficial not only to reconstruction of spine alignment but also to the formation of sagittal pelvic morphology.

To evaluate the clinical outcomes of posterior surgical corrective methods for ankylosing spondylitic kyphosis.From June 2003 to June 2008, 21 cases of ankylosing spondylitic kyphosis received posterior surgical correction. There were 17 male and 4 female, and the average age was 39.5 years (range, 20 to 57 years). The total spine X-ray and CT were used to evaluate sagittal balance and thoracolumbar spine kyphosis angle, and chin brow-vertical angle was obtained from clinical lateral photograph. The surgical goal was to correct sagittal imbalance and chin brow-vertical angle. The simulated osteotomy was performed in computer before surgery to determine the correction methods. The surgical methods included: 16 cases of monosegmental closing osteotomy correction, 3 cases of anterior opening-posterior closing osteotomy correction, and 2 cases of combined pedicle subtraction osteotomy in thoracolumbar spine and Smith-Peterson osteotomy in lumbar spine. All patients were followed up after surgery, and the improvement of sagittal imbalance, chin brow-vertical angle and thoracolumbar spine kyphosis angle were assessed. The symptoms relief and satisfied rate were also evaluated.The average operation time was 4.4 hours, and the average blood loss was 1770 ml. Before surgery, the average thoracolumbar kyphosis angle was 62.1°, the average anterior shift of C(7) plumb line was 172.9 mm, and the average chin brow-vertical angle was 34.9°. The average follow-up was 28.8 months after surgery. The average correction rate of thoracolumbar kyphosis angle was 60%, the average improvement rate of anterior shift of C(7) plumb line was 64%, and the average correction rate of chin brow-vertical angle was 98%. The improvement rate of back pain was 64% during follow-up. The total surgical satisfactory rate was 95%.Based on the simulated osteotomy in computer before surgery, according to the characteristics of ankylosing spondylitic kyphosis, different posterior osteotomy and correction methods can achieve good results.

To design a new surgical correction and fixation technique for the treatment of severe angular kyphosis, observe the feasibility, safety and effectiveness of the technique.From May 2004 to February 2007, 16 cases with severe kyphosis (average 90.8 degrees, range 50 degrees-130 degrees) were treated with segmental resection osteotomy, section distraction, dual axial rotation correction and instrumentation fusion technique. The patients were inspected by local and total spine anteroposterior and lateral radiography pre-and postoperatively. The kyphotic Cobb angle was measured and 7 cases combined scoliosis Cobb angle was also measured. The Frankel Grading for neurological function, Oswestry Disability Index (ODI) and Patients Satisfactory Index (PSI) were evaluated preoperatively, postoperatively and at follow-up. The back pain relief was also observed.The average surgical duration was 6.9 hours. The average blood loss was 4000 ml. The complications include 1 shifting of artificial vertebrae, 3 nerve root injury, 3 dural tear and 1 transitory dysfunction of lower extremity. All of these complications were relieved greatly after feasible treatment. The average follow-up time was 25 months. The average kyphotic angle was 90.8 degrees preoperatively, which was improved to 26.9 degrees immediately after surgery, and got an average correction rate of 72.5%. At follow-up, the average kyphotic angle was 28.9 degrees, and correction rate was 70.1%. The 7 cases who combined with scoliosis had an average Cobb angle of 35.9 degrees preoperatively, which decreased to 4.4 degrees immediately after surgery, and the correction rate was 87.2%. The correction rate was kept until follow-up (78.6%). Some patients got an improved neurological function. The Frankel Grading were E in 5 cases, D in 5 cases, C in 5 cases, and B in 1 case preoperatively. There were 10 cases of E grade, 3 cases of D grade, and 3 cases of C grade at follow-up. Except 3 cases who had no symptoms before surgery, the average ODI was 18.9 preoperatively, and 10.8 postoperatively. The average improvement of ODI was 52.7%. The PSI result showed a satisfied rate of 93.8%. The back pain of 3 cases were totally relieved after surgery.Segmental resection osteotomy with dual axial rotation correction and fusion technique is an effective way to treat severe angular kyphosis. It is a safe technique and has high correction rate. The long-term results is acceptable.