Objectives: To determine the frequency where a posterior and cranial screw in a femoral neck that appeared contained on fluoroscopy violates the cortex. Methods: Ten specimens including the hemipelvis with the proximal femur were obtained from unidentified embalmed specimens that were to be cremated after an institutional review board waiver was granted. Under fluoroscopy, the posterior and cranial screw of the inverted triangle configuration for the femoral neck was placed using standard technique with a cannulated 6.5-mm screw. Anterior–posterior and lateral images of the final screw placement were blinded to 2 orthopaedic traumatologists and 1 musculoskeletal radiologist who were asked to determine whether the screw radiographically breached the posterior and cranial cortex. Cadavers were stripped of soft tissues and inspected for screw perforation. Screws were grouped as contained, thread extrusion, or core extrusion. Results: Reviewers classified all 10 screws as radiographically contained within the femoral neck. Cadavers were inspected and found to show: 4 of 10 with core extrusion, 3 of 10 with thread extrusion, and 3 of 10 screws contained within the femoral neck. Conclusions: Seventy percent of screws that were judged to be radiographically contained had cortical breach near the area where the lateral epiphyseal vessels enter the femoral neck. We urge caution against placement of posterior-cranial implants with fluoroscopy alone even if they appear radiographically contained.
Background Since posterior cervical fixation with lateral mass screws was introduced in 1979, multiple techniques have been described in the literature. However, no study to date has determined whether pre-drilling all lateral masses prior to screw insertion has a benefit over the traditional sequential drilling and screw insertion on the alignment of the screw-rod construct. This study sought to determine the efficacy and efficiency in achieving alignment with a novel pre-drilling technique compared to the traditional sequential drilling technique. The authors hypothesized that the novel pre-drilling technique could be applied more quickly and precisely than the traditional sequential drilling technique. Methods Eight cervical spine sawbones models were utilized to place 64 lateral mass screws by two surgeons. The pre-drilling technique was utilized to place 32 screws in four models, and the sequential drilling technique was utilized to place the 32 screws in the remaining four models. In the traditional sequential drilling technique, each lateral mass underwent screw tract preparation and insertion before proceeding to the subsequent vertebra. In the pre-drilling technique, all lateral masses were marked and drilled sequentially before screw placement. CT imaging with 3D reconstructions was generated for all models. Variability in screw placement and time taken to fully instrument the models were compared. Results The mean time to completion of the pre-drilling technique was 337 ± 22 seconds compared to 490 ± 22 seconds with the traditional technique (p<0.01). There was a significantly higher variability in the coronal plane within the traditional group between C5 and C6 compared to other adjacent vertebrae (p<0.05). There was no significant difference in the start point variability and the overall tightness of line fit between the techniques. Conclusions Our study suggests that a novel pre-drilling technique for lateral mass screw insertion may be more efficient and reliable than the traditional sequential drilling technique. In addition, this technique may reduce the need for rod contouring or additional implants to optimize the alignment of cervical instrumentation. However, further clinical studies are necessary to validate the potential clinical and radiologic benefits of this described technique.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.