Von mises stress on the influence of pelvic stability by precise sacral resection and clinical validation / 中国组织工程研究

BACKGROUND: Sacral resection has now become the accepted treatment of choice for malignant tumors of the sacrum. There are few biomechanical studies on whether fractures or sacroiliac joint spondylolisthesis will occur after simple sacral resection, and there is no consensus on whether the weight can be fully loaded after subtotal sacral resection and when to rebuild. OBJECTIVE: To contrast clinical research and analyze Von Mises stress to provide a credible theoretic basis about which level of sacrectomy without spinopelvic reconstruction is acceptable for pelvic stability through the biomechanical testing of intact pelvis and models of pelvis after subdivided sacrectomy. METHODS: (1) Biomechanical research: Six fresh normal adult human cadaveric L5-pelvis specimens were chosen. Compressive stress loaded on the specimens was increased by 200 N, until 1 000 N, at the speed of 1.4 mm/min. The change of Von Mises stress was measured to the same pelvic specimens on intact sacrum and groups of subdivided sacrectomy. The differences were compared between groups of data. (2) Clinical studies: Totally 15 patients diagnosed with high sacral tumor with tumor resection between January 2012 and June 2019 were enrolled, including 6 males and 9 females with an average age of 46.40±14.94 years. According to preoperative MRI examination, the extent of sacral involvement was determined, and the size of sacral resection was determined. No reconstruction was performed after operation. Postoperative function and complications were recorded. RESULTS AND CONCLUSION: (1) Biomechanical research: With the growth of the sacrum resection plane, Von Mises stress had different increases at different test points, particularly by 1/4 S1 to 1/2 S1, which were apparently different with that in other groups (P < 0.05). Compared with group 2/3 S2 and group 1/3 S2, the change of Von Mises stress at point A in group S1-2 was not statistically significant. (2) Clinical results: Among the 15 patients, 4 patients retained the intact S1 vertebral body during the operation (resection of the S1-S2 intervertebral space, as in the biomechanics experiment S1-2 group); sacrum was resected in 3 patients as the group 2/3 S2 during the operation, and sacrum was resected in 2 patients during the operation as group 1/3 S2; and the S1 and S2 vertebrae were kept intact in 6 patients (as resection in the S2-3 group). The mean score of musculoskeletal tumor society was 25.27±3.79. All patients were able to walk, nine without walking aids, six with walking aids, one of them developed residual sacral fracture. (3) With the growth of the sacrum resection plane, Von Mises stress at residual sacrum rapidly rose. When the sacrum was resected by S1-S2 intervertebral space, the stability of the pelvic ring was acceptable without spinopelvic reconstruction.

Trans-Sacral Local Resection as a Posterior Approach

PURPOSE: Surgical removal for a mass in the pre-sacral space or mid rectum through a posterior approach is not frequent. We would like to present the technique of trans-sacral local resection as a posterior approach. We analyzed the follow up of patients who underwent surgery using the proposed technique. METHODS: A total of 21 patients who had undergone a trans-sacral local resection with lower sacrectomy between January 1997 and December 2006 were enrolled in this study. The diagnoses were large epidermal cyst, gastrointestinal stromal tumor, high grade adenoma, and early cancers in the mid rectum. We analyzed the surgical complications and disease recurrences. The mean follow up for tumors of the rectum was 53+/-35 mo. RESULTS: Epidural anesthesia was appropriate for all whole procedures. Among the 21 cases, there was one case of a rectocutaneous fistula as a postoperative complication (4.9%). In one case among the submucosal cancers, there was a systemic metastasis at 24 mo without local recurrence. CONCLUSION: In our experience, a trans-sacral resection with a lower sacrectomy is a good option and provides a wide and direct surgical exposure for the removal of a pre-sacral or a mid-rectal mass. Good bowel preparation is mandatory.

Sacrococcygeal Chordoma / 대한정형외과학회잡지

Sacrococcygeal chordoma is a rare malignant tumor which is believed to take its origin from remnants of the fetal notochord, and presents in the sacral hollow or occasionally posteriorly. The growth is leisurely and it is invasive rather than metastatic. In treatment, there is evidence that early diagnosis of sacrococcygeal chordoma followed by radical resection c palliative radiotherapy does provide the opportunity for cure. We have experienced two cases of sacrococcygeal chordoma, which were treated with one case of a complete surgical resection and the other case of only biopsy.