The most important predictor of survival for patients with sacral chordomas is an initial en bloc resection with negative margins. However, obtaining negative margins can be technically challenging. Intraoperative navigation may be helpful in attempting an excision with negative margins.
This is the first report of partial sacrectomy guided by frameless stereotactic navigation.
Three patients with a mean age of 58.7 years underwent en bloc resection of sacral chordomas aided by image guidance. Intraoperatively, the reference arc was clamped to the spinous process of L5 and the bony landmarks of S1 were used for registration. Subsequently, the drill was registered, allowing the osteotomy trajectory to be visualized in real time with reference to the patients' anatomy and tumor location.
None of the patients had any intraoperative or postoperative complications. Two patients with smaller tumors (5 cm) had negative margins, whereas the third patient with an 11.5 cm tumor had marginal margins. With an average follow-up of 44 months, none of the patients have had a recurrence of the tumor.
The use of frameless stereotaxy during the en bloc resection of sacral tumors is safe and feasible. Frameless stereotactic navigation was a useful adjunct to preoperative imaging and to the surgeon's anatomic knowledge. Image guidance was used during the osteotomies to decrease the likelihood of injury to vital adjacent structures or violation of the tumor capsule and to increase the likelihood that the appropriate surrounding tissue was resected to attempt a wide or marginal resection.
[Show abstract][Hide abstract] ABSTRACT: Surgical resection margins are reportedly the most important predictor of survival and local recurrence with sacral chordomas. We examined the relevance of invasion of the surrounding posterior pelvic musculature (piriformis and gluteus maximus) at initial diagnosis to local recurrence after sacrectomy. We retrospectively reviewed 18 patients with histologically verified sacral chordoma seen at our institution between 1998 and 2005. There were 14 men and four women with a mean age of 65.1 years (range, 31-78 years). The average overall followup was 4.4 years (range, 0.5-10 years), 5.4 years for the living patients (range, 3-10 years), and 2.8 years for the deceased (range, 0.5-5.4 years). Local recurrence occurred in 12 patients (66%) 29 months postoperatively (range, 2-84 months). Six of these patients had wide excisions at initial surgery, five had marginal excisions, and one had an intralesional excision. Ten patients had wide surgical margins, six of whom (60%) had local recurrences. Tumor invasion of adjacent muscles at presentation was present in 14 patients, 12 of whom (85%) had local recurrences. Sacroiliac joint involvement was seen in 10 patients, nine of whom (90%) had local recurrences. The findings suggest obtaining wide surgical margins posteriorly, by excising parts of the piriformis, gluteus maximus, and sacroiliac joints, may result in better local disease control in patients with sacral chordoma. Level of Evidence: Level IV, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Clinical Orthopaedics and Related Research 07/2008; 466(9):2217-23. DOI:10.1007/s11999-008-0356-7 · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although transpedicular fixation is a biomechanically superior technique, it is not routinely used in the cervical spine. The risk of neurovascular injury in this region is considered high because the diameter of cervical pedicles is very small and their angle of insertion into the vertebral body varies. This study was conducted to analyze the clinical accuracy of stereotactically guided transpedicular screw insertion into the cervical spine.
Twenty-seven patients underwent posterior stabilization of the cervical spine for degenerative instability resulting from myelopathy, fracture/dislocation, tumor, rheumatoid arthritis, and pyogenic spondylitis. Fixation included 1-6 motion segments (mean 2.2 segments). Transpedicular screws (3.5-mm diameter) were placed using 1 of 2 computer-assisted guidance systems and lateral fluoroscopic control. The intraoperative mean deviation of frameless stereotaxy was < 1.9 mm for all procedures.
No neurovascular complications resulted from screw insertion. Postoperative computed tomography (CT) scans revealed satisfactory positioning in 104 (90%) of 116 cervical pedicles and in all 12 thoracic pedicles. A noncritical lateral or inferior cortical breach was seen with 7 screws (6%). Critical malplacement (4%) was always lateral: 5 screws encroached into the vertebral artery foramen by 40-60% of its diameter; Doppler sonographic controls revealed no vascular compromise. Screw malplacement was mostly due to a small pedicle diameter that required a steep trajectory angle, which could not be achieved because of anatomical limitation in the exposure of the surgical field.
Despite the use of frameless stereotaxy, there remains some risk of critical transpedicular screw malpositioning in the subaxial cervical spine. Results may be improved by the use of intraoperative CT scanning and navigated percutaneous screw insertion, which allow optimization of the transpedicular trajectory.
[Show abstract][Hide abstract] ABSTRACT: This is a retrospective study conducted to evaluate the efficacy of single versus separate registration in assessing the pedicle screw accuracy in the computer-assisted lumbar spinal instrumentation.
To see if separate registration reduced lumbar pedicle screw misplacement.
Computer-assisted spinal instrumentation has been shown to improve pedicle screw installation accuracy, but 2.7% to 8% of screws still perforate the pedicular cortex. Suspected causes include differences in lumbar lordosis between preoperative CT scans and surgery.
Postoperative radiographs and CT scans were used to assess the accuracy of pedicle screw placement in 47 adult patients following computer-assisted lumbar spinal instrumentation. Twenty-two patients underwent single registration at one level, while the other 25 underwent registration at each level.
The time required for a registration procedure on one level was 6 to 8 minutes, while the time required for application of a pedicle screw using computer-assisted techniques was an additional 6 to 10 minutes. The total number of screw placements was 118 in the single registration group and 130 in the separate registration group. In the former group, 85 (72%) pedicle screw placements were categorized as good, 28 (24%) were fair, and 5 (4%) were poor. All five poorly placed screws were placed in the lower lumbar or upper sacral spine with high mobility, and at levels without registration, with one causing root injury. In the latter group, 117 (90%) pedicle screw placements were good and 13 (10%) were fair. The difference in placement was found to be statistically significant (chi2, P = 0.0003). CONCLUSION.: Before the intraoperative real-time CT imaging is widely used, separate registration at each instrumented level during traditional computer-assisted lumbar spinal instrumentation is necessary to enhance the accuracy of screw placement.
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