[Show abstract][Hide abstract] ABSTRACT: Study Design: A prospective study. Objective: To provide methods for predicting ideal trajectory and position of C1 lateral mass screw (C1LMS) from plain radiographs. Summary of Background Data: There has been no study on prediction of C1LMS position using plain radiographs. Methods: A total of 40 consecutive subjects (with 79 screws) who had undergone C1LMS placement were enrolled. To evaluate the C1LMS position, the positions of screw head and tips on anteroposterior (AP) radiographs, screw length and height on lateral radiograph were graded; 0, I and II respectively. On the postoperative computed tomography (CT) images, we analyzed lateral mass (LM) perforation, screw thread engagement percent (%), bicortical fixation, extruded screw length and violation of adjacent joints. Results: Screws with tip located medial to LM (tip 0) showed LM perforation in all cases. Polyaxial head located within LM (head 0) or cross the lateral margin of LM (head I) showed no LM perforation. Screw thread engagement percent was highest with head I-tip I (medial half of LM) position (97.6%) and followed by head 0-tip I (90.5%), head I-tip II (lateral half of LM) (86.4%). Screws longer than posterior half of C1 anterior arch (AA) showed bicortical fixation in all cases with mean extruded screw length of 1.9[medium shade]mm. Adjacent joint was not violated in 98% with the screw height below half of C1AA. Conclusions: On an AP radiograph, a C1LMS with the screw head located on the lateral margin of the LM and with the screw tip in the medial half of the LM resulted in the safest and longest trajectory. On lateral radiograph, a screw tip that is placed within the anterior-inferior quadrant of the C1AA result in safe bicortical fixation without injury to the adjacent structures. These plain radiographic findings may be helpful both postperatively and intra-operatively for assessing the trajectory and length of the screw.
No preview · Article · Jun 2014 · Journal of Spinal Disorders & Techniques
[Show abstract][Hide abstract] ABSTRACT: Study design:
A technical note and a retrospective review of cervical osteotomy using an innovative reduction technique.
To present the clinical and radiological outcomes and effectiveness of the sterile-freehand reduction technique for cervical osteotomy. SUMMARY OF BACKGROUD DATA: For a successful osteotomy, controlled reduction of deformity after complete release of bony deformity is the most critical step. Conventional "unscrubbed-scrubbed" manual reduction techniques necessitate multiple releases and retightening of the clamp and are inconvenient for the surgeon to control the force and monitor the surgical field closely.
A total of 7 consecutive patients (5 male and 2 female; mean age, 52.6 yr) who underwent corrective osteotomy of the fixed cervical kyphosis by a single surgeon were enrolled. Radiographically, C2-C7 sagittal and coronal angle, and the chin-brow vertical angle were measured. In the prone position, the entire head and the Gardner-Wells tong were included in the surgical field, and a sterile rope was connected to a weight through a hole made in the surgical drape. After complete release of bony element and fixation of the caudal part of osteotomy with a prebent lordotic rod, the operator held the tong with right hand and gradually reduced the deformity to place the rod within the screw heads on the cranial part of osteotomy under close visual observation, with the support of the caudal part with left hand. RESULTS.: The type of osteotomy performed was pedicle-subtraction osteotomy in 5 cases and anterior-release-posterior osteotomy in 2 cases. The mean correction angle was 39.7° (28°-63°) on the sagittal plane and 9.3° (0°-16°) on the coronal plane. The mean correction of the chin-brow vertical angle was 37.1° (18°-61°). There was no neurovascular complication.
Using the sterile-freehand reduction technique, the operator can obtain a safe, controlled reduction with close monitoring of the surgical field. The technique is potentially a simple and effective method to provide stable, 3-dimensional reduction for corrective osteotomies of the cervical spine.