Biomedical subjects

L P Amiot

Publications and source records attributed to L P Amiot.

6 recordsLinked to original sources

PubMed2002

[Computer navigation in dorsal instrumentation of the cervical spine--an in vitro study].

Transarticular C1/2 screws are widely used in posterior cervical spine instrumentation. Pedicle screws in the cervical spine remain uncommon until now. In view of improved biomechanical stability compared to lateral mass screws, pedicle screws could be used, especially for patients with poor bone quality or defects in the anterior column. Nevertheless, there are potential risks of iatrogenic damage to the spinal cord, nerve roots, or the vertebral artery related to both techniques of posterior cervical spine instrumentation. Therefore, the aim of this study was to evaluate whether C1/2 transarticular screws as well as transpedicular screws in C3 and C4 can be applied safely and with high accuracy using a computer-assisted surgery (CAS) system. C1/2 transarticular screws as well as transpedicular screws in the cervical spine can be applied safely and with high accuracy using a CAS system in vitro. Therefore, this technique may be used in the clinical setup due to improved accuracy and reduced radiation dose for the patient and medical staff. Nevertheless, to prevent iatrogenic damage, users should be aware of known sources of possible errors that cause inaccuracies. Small pedicles with a diameter below 4.0 mm may not be suitable for pedicle screws.

Aged↗

PubMed2000

Comparative results between conventional and computer-assisted pedicle screw installation in the thoracic, lumbar, and sacral spine.

STUDY DESIGN: A comparative study on the position of pedicle screws in patients treated surgically with and without computer assistance. OBJECTIVES: To evaluate the accuracy of computer-assisted pedicle screw installation, and to evaluate its clinical benefit as compared with conventional pedicle screw installation techniques. SUMMARY OF BACKGROUND DATA: In vitro and clinical studies have documented a significant rate of misplaced screws in the thoracolumbar area. Neurologic complications are recognized problems caused by screw misplacement. METHODS: Patients treated surgically with computer assistance were compared with a historical control group of patients treated surgically with conventional techniques in the same hospital and by the same surgical team. All screw positions were measured with a postoperative magnetic resonance tomography, and cortical effractions were categorized in 2-mm increments. Patients' charts also were reviewed to assess individual neurologic outcomes. RESULTS: The control cohort was composed of 100 patients, with 544 screws from T5 to S1. The computer-assisted cohort was composed of 50 patients, with 294 screws from T2 to S1. In the control cohort, 461 of 544 screws (85%) were found completely within their pedicles as compared with 278 of 294 screws (95%) correctly placed in the computer-assisted group (P < 0.0001). All 16 screws incorrectly placed with computer assistance were found 0.1 mm to 2 mm from the pedicle cortex. In the control cohort, 68 screws were found 0.1 mm to 2 mm, 10 screws 2.1 mm to 4 mm, and 5 screws more than 4 mm from the pedicle cortex. Seven patients in the control cohort were surgically retreated because of postoperative neurologic deficits, whereas no patients in the computer-assisted group were surgically retreated. CONCLUSIONS: Computer assistance can decrease the incidence of incorrectly positioned pedicle screws.

Bone Screws↗

PubMed2000

Computer-assisted surgery in posterior instrumentation of the cervical spine: an in-vitro feasibility study.

Transarticular C1/2 screws are widely used in posterior cervical spine instrumentation. The use of pedicle screws in the cervical spine remains uncommon. Due to superior biomechanical stability compared to lateral mass screws, pedicle screws can be used, especially for patients with poor bone quality or defects in the anterior column. Nevertheless there are potential risks of iatrogenic damage to the spinal cord, nerve roots or the vertebral artery associated with both posterior cervical spine instrumentation techniques. Therefore, the aim of this study was to evaluate whether C1/2 transarticular screws as well as transpedicular screws in C3 and C4 can be applied safely and with high accuracy using a computer-assisted surgery (CAS) system. We used 13 human cadaver C0-C5 spine segments. We installed 1.4-mm Kirschner wires transarticular in C 1/2, using a specially designed guide, and drilled 2.5-mm pedicle holes in C3 and C4 with the assistance of the CAS system. Hole positions were evaluated by palpation, CT and dissection. Forty-eight (92%) of the 52 drilled pedicles were correctly positioned after palpation, imaging and dissection. The vertebral artery was not injured in any specimen. All of the 26 C1/2 Kirschner wires were placed properly after imaging and dissection evaluations. No injury to vascular or bony structures was observed. C /2 transarticular screws as well as transpedicular screws in the cervical spine can be applied safely and with high accuracy using a CAS system in vitro. Therefore, this technique may be used in a clinical setting, as it offers improved accuracy and reduced radiation dose for the patient and the medical staff. Nevertheless, users should take note of known sources of possible faults causing inaccuracies in order to prevent iatrogenic damage. Small pedicles, with a diameter of less than 4.0 mm, may not be suitable for pedicle screws.

Aged↗

PubMed1997

[In vitro evaluation of computer-assisted pedicle screw system].

GOAL: The goal of this study is to evaluate influence on the accuracy of pedicle hole positions when a surgeon uses a computer assisted system. STUDY DESIGN: This comparative study was undertaken using dry thoraco-lumbar specimens in order to measure the position of drilled holes with and without computer assistance in the hands of an experienced surgeon as well as with a resident in training. METHODS: Pedicle holes were drilled from D1 to L5 in identical dry thoraco- lumbar specimens. For half of the specimens a computer assisted pedicle screw installation system was used. Holes having been drilled for all specimens, we then measured the maximum distance between the axis of the drilled holes and the pedicle cortices All distances less or equal to 2 mm were classified as safe while all bigger distances were classified as unsafe for pedicle screw installation. RESULTS: Nine specimens were drilled for a total of 306 holes, 170 of them with computer assistance. We have observed a 95% success rate with the computer assisted holes compared to a 62% success rate using conventional methods (p < 0.001). No difference was found between the results of an experienced surgeon and the results of a resident in training while using the computer assistance system. All holes drilled from D12 to L5 were found to be in optimal position, completely within the pedicles. CONCLUSION: These results suggest that this computer assisted pedicle screw installation system could improve the accuracy of pedicle screw placement and enhance the safety of the procedure. Moreover, the computer system could become a valuable teaching tool for the training spine surgeons.

Bone Screws↗

PubMed1996

[Computer assisted pedicle screw installation. Our first 3 cases].

Pedicle screw fixation is sometimes a difficult surgical procedure relying on anatomical landmarks that may be modified by vertebral asymmetries. A significant incidence of cortex penetration and neuro-vascular complications have been documented. Our study evaluates the usefulness of a computer-aided pedicle installation system and analyses the results for our first 3 clinical cases. The system was used for 3 adolescent patients with idiopathic scoliosis undergoing surgical correction and instrumentation. In all cases, selected vertebrae were reconstructed in 3D pre-operatively. At surgery, the surgeon compared the computer-suggested pedicle location to his own opinion. After pedicular hole drilling was done in the usual fashion, hole positions were confirmed per-operatively with the computer software. Post-operatively, software hole positions were measured and compared to the actual screw axis using CT-Scans. Three dimensional models produced for all selected vertebrae allowed visualization of asymmetrical deformations of the scoliotic vertebrae. All pedicles were correctly detected by the software. Pedicular hole measurements agreed with the actual screws positions on post-op CT-Scans. The computerized surgical assistant can be of value in a clinical situation. These initial results warrant a large scale trial in order to establish accuracy and reliability.

Adolescent↗

PubMed1995

Computer-assisted pedicle screw fixation. A feasibility study.

STUDY DESIGN: We evaluated a computer-assisted surgical tool for inserting pedicle screws. OBJECTIVES: This study reviewed the feasibility, usefulness, and accuracy of the proposed tool. SUMMARY OF BACKGROUND DATA: Reviews documented neurovascular damage caused by screw misplacement. Currently, screw hole position is assessed by radiologic means and curette palpation. METHODS: Three sheep vertebrae and one artificial object were reconstructed three-dimensionally from computed tomography scan slices. At surgery, the surgeon's movements were displayed relative to the three-dimensional vertebrae on a computer screen. The tool was used to detect pedicles and to verify the position of drilled holes. In our laboratory, we calculated the system's accuracy by taking measurements on the artificial object. RESULTS: All pedicles were identified with the computer. Five of the six drilled hole positions were correctly represented. An accuracy of 4.5 mm +/- 1.1 mm RMS (root of the mean squared) and 1.6 degrees +/- 1.2 degrees were calculated. CONCLUSIONS: Results suggested the proposed system could be useful for pedicle detection and assessing the intravertebral location of a drilled hole. The proposed system could be used for many different orthopedic procedures where structures are hidden from the surgeon's view.

Animals↗