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Objective To compare biomechanical properties of cortical bone trajectory (CBT) screw and traditional trajectory screw for fixing upper-middle thoracic spine. Methods The tomography images were obtained by CT scanning of normal T7 and T8 segments, and the three-dimensional (3D) model of T7-8 was reconstructed by Mimics software. The finite element model of upper-middle thoracic spine was established by optimizing FreeForm model and pre-processing function of ANSYS software. On this basis, the CBT screw and pedicle screw fixation models after discectomy were established, and 5 N·m flexion, extension, lateral bending and rotation loads were applied to the two model groups, respectively. The displacement and peak stress of vertebrae and implants under different working conditions were compared and analyzed. Results Under different loading conditions, the maximum displacement of CBT screw group was lower than that of pedicle screw group, and the range of motion of CBT screw group was lower than that of pedicle screw group. The stress level of both models was close, and the stress of CBT screw group was slightly lower than that of pedicle screw group. Under the load of flexion, extension and rotation, the maximum vertebral stress of pedicle screw group decreased by 31%, 17% and 18% compared with that of CBT screw group, and under lateral bending load, the vertebral stress of CBT screw group was 20% lower than that of pedicle screw group. Under the load of flexion and rotation, the maximum stress of pedicle screw group decreased by 2% and 11%; however, the maximum stress of CBT screw group was 11% and 1% lower than that of pedicle screw group. Conclusions The stability of CBT screw was better than that of pedicle screw, and the overall stress distribution was similar to that of pedicle screw. However, the vertebral stress distribution of CBT group was slightly inferior. The research findings provide a theoretical basis for the clinical application of cortical screw fixation after the failure in pedicle screw fixation for the upper-middle thoracic vertebrae.
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Objective To study the local recurrent pattern of postoperative middle thoracic esophageal squamous cell carcinoma( ESCC) and provide the evidence for designing the radiation target in postoperative radiotherapy. Methods From May 2007 to December 2015, a total of 752 patients with local recurrence of postoperative middle thoracic ESCC were included in this retrospective analysis. χ2 test was used to analyze the recurrent pattern of mediastinum, anastomotic, abdominal cavity and primary tumor bed. Results The median interval between surgery and recurrence was 14. 6 months (1-106 months). The highest risk of recurrent site was mediastinum (79. 7%), followed by supraclavicular and anastomotic (29. 1%and 7. 4%, respectively), but rarely occurred at the abdominal cavity and primary tumor bed (4. 1%and 0. 7%, respectively). The relapse rate differed significantly among the five sites (χ2 =925. 8, P<0. 05). Furthermore, the relative metastatic rate in upper mediastinum was 74. 2%, 19. 8%in middle mediastinum and 4. 8%in the lower. There was statistically significant difference in the relative metastatic rate among the three sites(χ2 =791. 6, P <0. 05). Recurrences occurred highly at the 7th, 1st -5th regions, but rarely at 6th, 8th -10th regions. There was significant difference among these 10 regions from the mediastinum(χ2 =486. 9, P<0. 05). The lymphatic metastasis of superior mediastinum was mainly distributed at paratracheal lymph nodes. The metastatic rate of right paratracheal lymph nodes was 47. 1% including 1R,2R and 4R regions and the left paratracheal lymph nodes was 29. 4%including 1L, 2L and 4L regions. The metastatic rate of right supraclavicular paratracheal lymph nodes was significantly higher than that of left ones(χ2 =31. 5, P <0. 05). Conclusions Local recurrence mainly occurred in the bilateral supraclavicular areas, upper/middle mediastinum and anastomosis in patients with middle thoracic ESCC. The bilateral supraclavicular areas, 1st -5th regions of superior mediastinum, 7th region of middle mediastinum and anastomosis should be included in the postoperative prophylactic irradiation target volume.
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Objective To study the local recurrent pattern of postoperative middle thoracic esophageal squamous cell carcinoma( ESCC) and provide the evidence for designing the radiation target in postoperative radiotherapy. Methods From May 2007 to December 2015, a total of 752 patients with local recurrence of postoperative middle thoracic ESCC were included in this retrospective analysis. χ2 test was used to analyze the recurrent pattern of mediastinum, anastomotic, abdominal cavity and primary tumor bed. Results The median interval between surgery and recurrence was 14. 6 months (1-106 months). The highest risk of recurrent site was mediastinum (79. 7%), followed by supraclavicular and anastomotic (29. 1%and 7. 4%, respectively), but rarely occurred at the abdominal cavity and primary tumor bed (4. 1%and 0. 7%, respectively). The relapse rate differed significantly among the five sites (χ2 =925. 8, P<0. 05). Furthermore, the relative metastatic rate in upper mediastinum was 74. 2%, 19. 8%in middle mediastinum and 4. 8%in the lower. There was statistically significant difference in the relative metastatic rate among the three sites(χ2 =791. 6, P <0. 05). Recurrences occurred highly at the 7th, 1st -5th regions, but rarely at 6th, 8th -10th regions. There was significant difference among these 10 regions from the mediastinum(χ2 =486. 9, P<0. 05). The lymphatic metastasis of superior mediastinum was mainly distributed at paratracheal lymph nodes. The metastatic rate of right paratracheal lymph nodes was 47. 1% including 1R,2R and 4R regions and the left paratracheal lymph nodes was 29. 4%including 1L, 2L and 4L regions. The metastatic rate of right supraclavicular paratracheal lymph nodes was significantly higher than that of left ones(χ2 =31. 5, P <0. 05). Conclusions Local recurrence mainly occurred in the bilateral supraclavicular areas, upper/middle mediastinum and anastomosis in patients with middle thoracic ESCC. The bilateral supraclavicular areas, 1st -5th regions of superior mediastinum, 7th region of middle mediastinum and anastomosis should be included in the postoperative prophylactic irradiation target volume.
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OBJECTIVE : Percutaneous approach to the middle thoracic vertebra through the transpedicular route for the patients with osteoporotic vertebral compression fractures is difficult due to the small size of the pedicle and parasagittally oriented vertebral body anatomy. The percutaneous vertebral body access (PVBA) technique utilizing the posterolateral extrapedicular approach avoids the pedicle and provides direct access to the vertebral body. The objective of this study is to evaluate the efficacy of the vertebroplasty utilizing PVBA technique for osteoporotic vertebral compression fractures in the middle thoracic vertebrae. METHODS : A retrospective review was done on 20 patients who underwent vertebroplasty utilizing PVBA technique performed for painful osteoporotic compression fracture in the middle thoracic vertebrae at 22 levels from May 2003 to June 2006. The average amount of the injected cement was 1.5-2.5ml. The postprocedural outcome was assessed using a visual analogue scale (VAS). RESULTS : The treated vertebrae were T5 (1 level), T6 (5 levels), T7 (7 levels), and T8 (9 levels). The compression rate and kyphotic angle were improved after procedure from 18%+/-13.4 to 16%+/-13.8 (p>0.05) and from 6.9degrees+/-6.7 to 6.6degrees+/-6.2 (p>0.05), respectively. Preprocedural VAS was 8.2+/-0.70 and was decreased to 2.1+/-1.02 (p<0.01) after treatment. Postprocedural cement leakage was noted in 3 levels (13.7%). There were no cases of leakage to epidural space or neural foramen, segmental artery injury, and pneumothorax. CONCLUSION : These results suggest that the complication rates are low and good results can be achieved with vertebroplasty utilizing PVBA technique for the osteoporotic vertebral compression fractures especially in the middle thoracic vertebrae.
Subject(s)
Humans , Arteries , Epidural Space , Fractures, Compression , Osteoporosis , Pneumothorax , Retrospective Studies , Spinal Fractures , Spine , Thoracic Vertebrae , VertebroplastyABSTRACT
OBJECTIVE: Kyphoplasty performed in the middle thoracic spine presents technical challenges that differ from those in the lower thoracic or lumbar region due to small pedicle size and angular severity for thoracic kyphosis. The purpose of this study was to evaluate the efficacy of balloon kyphoplasty through extrapedicular approach for the treatment of intractable osteoporotic compression fractures in the middle thoracic spine. METHODS: The patients who were performed with one level balloon kyphoplasty through extrapedicular approach due to painful osteoporotic compression fractures at T5-T8 from June 2003 to July 2005 were retrospectively analyzed. Imaging and clinical features were analyzed including involved vertebrae level, vertebral height, injected cement volume, clinical outcome and complications. RESULTS: Eighteen female patients (age ranged from 60 to 77 years old) were included in this study. The average amount of the implanted cement was 4.2+/-1.5 cc. The mean cobb angle and compression rate were improved from 12.1+/-6.5 degrees to 8.5+/-7.2 degrees and from 30% to 15%, respectively. The mean pain score (visual analogue scale) prior to kyphoplasty was 7.9 and it decreased to 3.0 after the procedure. Cement leakage to the adjacent disc (2 cases) and paravertebral soft tissues (1 case) were seen but there were no major complications such as pneumothorax, segmental artery injury, pulmonary embolism, or epidural leakage. CONCLUSION: Balloon kyphoplasty through extrapedicular approach is considered as a safe and effective in treating the middle thoracic regions with low complication rate.