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ABSTRACT: Transarticular screw fixation is used in the upper cervical and lumbar spine to achieve posterior spinal stability, and its biomechanical performance has been proven to be similar to that of pedicle screw fixation. However, few studies have reported the use of transarticular screw fixation in the upper thoracic spine.
To biomechanically compare transarticular screws with pedicle screws in short-term cyclic loading in the upper thoracic spine.
Eight fresh human cadaveric spine specimens (T1-T3) were harvested and tested for 6 cycles in flexion, extension, lateral bending, and torsion in their intact condition. Each specimen was then destabilized and restabilized with 3 fixation methods: the pedicle screw/rod construct, the transarticular screw/rod construct, and transarticular screws alone. The instrumented specimens were reteted with the same protocol.
All fixation systems reduced the range of motion significantly with respect to flexion, extension, lateral bending, and axial rotation (P < .01). However, no significant difference was observed between the 3 instrumented groups.
This biomechanical study demonstrates in vitro that transarticular screws and pedicle screws have statistically similar biomechanical stability in a noncorpectomy model. Posterior transarticular screws may be an alternative for internal fixation in the upper thoracic spine.
Neurosurgery 12/2011; 69(2 Suppl Operative):ons141-5; discussion ons146. · 2.79 Impact Factor
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ABSTRACT: Although pedicle screw fixation has been increasingly used in the upper thoracic spine in recent years, controversies exist about the safety and complications such as nerve or vascular intrusion associated with the technique. In this study, an alternative method of transarticular screw fixation was validated.
Morphometric analysis was performed on computed tomography (CT) scans of the upper thoracic zygapophysial joints of C7, T1, T2 and T3 in 20 male and 20 female patients in the axial and sagittal planes. The degree of screw angulation was recorded in the sagittal and axial planes and the screw length was measured at the spinal level from C7 to T3.
The smallest medial-lateral diameter and anterior-posterior diameter of IAP was found at T3 in the female patients and C7 in the male patients. The screw trajectory length ranged from 14.9 to 20.5 mm in all patients. All the above measurements were significantly different between male and female patients at all levels (P < 0.05). The mean value of screw trajectory angle was 19.3°-20.1° in the axial plane and 44.3°-45.7° in the sagittal plane. There was no statistically significant difference (P > 0.05) between male and female patients in the axial and sagittal angles.
The morphometric data of C7-T3 zygapophysial joints indicate the suitable screw diameter and screw length for this technique. Transarticular screw fixation proved to be a potentially safe alternative to pedicle screw fixation in this region.
European Spine Journal 11/2011; 21(6):1186-91. · 1.97 Impact Factor
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ABSTRACT: BACKGROUND:: Transarticular screw fixation is used in the upper cervical and lumbar spine to achieve posterior spinal stability, and its biomechanical performance is proven to be similar to that of pedicle screw fixation. However, few studies have reported the use of transarticular screw fixation in the upper thoracic spine. OBJECTIVE:: To biomechanically compare transarticular screws with pedicle screws in short-term cyclic loading in the upper thoracic spine. METHODS:: Eight fresh human cadaveric spine specimens (T1-T3) were harvested and tested for six cycles in flexion, extension, lateral bending and torsion in their intact condition. Each specimen was then destabilized and restabilized with three fixation methods: the pedicle screw/rod construct, the transarticular screw/rod construct, and transarticular screws alone. The instrumented specimens were retested using the same protocol. RESULTS:: All fixation systems reduced the range of motion significantly with respect to flexion, extension, lateral bending and axial rotation (P<0.01). However, no significant difference was observed between the three instrumented groups. CONCLUSION:: This biomechanical study demonstrates in vitro that transarticular screws and pedicle screws have statistically similar biomechanical stability in a non-corpectomy model. Posterior transarticular screws may afford an alternative for internal fixation in the upper thoracic spine.
Neurosurgery 03/2011; · 2.79 Impact Factor
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ABSTRACT: To explore angioarchitectural features of brain arteriovenous malformations (BAVMs) in ages.
302 Consecutive patients with BAVMs between 1999 and 2008 were retrospectively reviewed. Univariate analysis was used to test initial presentation and BAVM characteristics in different ages.
Patients ranged in age from 5 to 65 years (mean±SD, 28.3±12.8). One hundred and eighty-eight were male and 113 female. Clinical presentations were hemorrhage (52.6%), seizure (24.5% of patients), headache (12.6%), focal neurological deficit (6.3%), or other clinical events, including incidental BAVM diagnoses (4.0%). Increasing age correlated positively with coexisting arterial aneurysms (P=0.044). No differences were found for sex, initial presentation, BAVM size, BAVM location, arterial feeders and venous drainage pattern between each age groups.
Increasing age correlated positively with coexisting arterial aneurysms. No statistical significance was observed for clinical presentations, and BAVM characteristics among age groups.
European journal of radiology 02/2011; 81(4):780-3. · 2.65 Impact Factor
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ABSTRACT: Currently available stents for intracranial use usually are Neuroform (Boston Scientific/Target, Fremont, CA) and Leo (Balt, Montmorency, France) stents. We present the results of our initial experience in using the Leo stent to treat patients with wide-necked cerebral aneurysms.
Fifteen consecutive patients with wide-necked intracranial aneurysm were treated with a combined approach that consisted of delivery of a flexible self-expending neurovascular stent through a microcatheter to cover the neck of the aneurysm and subsequent filling of the aneurym with coils through the stent interstices. We assessed the clinical history, aneurysm dimensions, and technical details of the procedures, including any difficulties with stent deployment, degree of aneurysm occlusion, and complications.
During a 1-year period, 15 patients with 17 broad-necked aneurysms (n = 13; average neck length, 5.1 mm; average aneruysm size, 9 mm) were treated with the Leo stent. Fifteen stents were deployed successfully; two failed. Of the coiled aneurysms, complete or subtotal (more than 95%) occlusion was achieved in 11 aneurysms, and partial occlusion was achieved in 2 aneurysms. One patient had multiple stents placed. One patient had a ruptured aneurysm at the time of treatment. Technical problems included difficulty in deploying the stent (n = 2). Two periprocedural thromboembolic complications occurred. One patient had palsy after thrombolysis was attempted. The other patient made an excellent functional recovery after undergoing successful thrombolysis of a thrombosed internal carotid artery stent.
Preliminary data demonstrated that the Leo stent is useful device for the treatment of patients with wide-necked aneurysms. In cases with tortuous cerebral vasculature, delivery and deployment may be technically challenging. Clinically significant complications are uncommon.
World Neurosurgery 04/2010; 73(4):379-84. · 0.68 Impact Factor
