Scott C. Fuller

Comparison of 3 Optical Navigation Systems for Computer-Aided Maxillofacial Surgery

OBJECTIVE To compare the accuracy of 3 computer-aided surgery systems for maxillofacial reconstruction. DESIGN Evaluation of 3 computer-aided surgery systems: StealthStation, VectorVision, and Voxim. SETTING The University of California, Davis, Department of Otolaryngology computer-aided surgery laboratory. PARTICIPANTS Four fresh cadaveric heads. MAIN OUTCOME MEASURE Mean target registration error. RESULTS The StealthStation was the most accurate (mean [SD] target registration error, 1.00 [0.04] mm), followed by VectorVision (1.13 [0.05] mm) and then Voxim (1.34 [0.04] mm). All values met statistical significance (P < .05). CONCLUSIONS Measurable accuracy differences were found among the navigation systems evaluated. The StealthStation was the most accurate. However, the differences are small, and the clinical significance for maxillofacial reconstruction is negligible.

Computer applications in facial plastic and reconstructive surgery

Purpose of reviewComputer applications in facial plastic and reconstructive surgery continue to evolve as image-guided surgical technology and software applications improve. Surgeons use these technological advances in order to simplify complex and historically challenging reconstructive issues. This paper reviews the recent literature pertaining to advances in computer-aided presurgical planning and intraoperative navigation. Recent findingsAlthough many different computer-aided surgical applications have previously been described, the recent literature focuses on orbital, midface and mandibular reconstruction. These studies highlight primary and secondary repair of complex maxillofacial trauma using computer software platforms for analysis of computed tomography data, presurgical planning, and intraoperative navigation. SummaryComputer-assisted facial reconstructive surgery is an area which continues to evolve. The current technology is best served in the repair of complex primary or secondary posttraumatic deformities. Congenital and oncologic reconstructive applications, however, are growing rapidly. While computer-aided surgery has historically been limited to tertiary care centers, easy access to intraoperative navigation systems and more user friendly software applications make these techniques more accessible to a greater number of surgeons.

Preformed vs Intraoperative Bending of Titanium Mesh for Orbital Reconstruction

Objective The most accurate orbital reconstructions result from an anatomic repair of the premorbid orbital architecture. Many different techniques and materials have been used; unfortunately, there is currently no optimal method. This study compares the use of preformed vs intraoperative bending of titanium mesh for orbital reconstruction in 2-wall orbital fractures. Study Design Cadaver-based study. Setting University hospital. Subjects and Methods Preinjury computed tomography scans were obtained in 15 cadaveric heads (30 orbits). Stereolithographic (STL) models were fabricated for 5 of the specimens (10 orbits). Two wall fractures (lamina papyracea and floor) were then generated in all orbits. Surgical reconstruction was performed in all orbits using 1 of 3 techniques (10 orbits each): (1) patient-specific implant molded from the preinjury STL model, (2) titanium mesh sheet bent freehand, and (3) preformed titanium mesh. Each technique was evaluated for orbital volume correction, contour accuracy, ease of use, and cost. Results No difference in volume restoration was found between the 3 techniques. Patient-specific implants had the greatest contour accuracy, poor ease of use, and highest cost. Freehand bending implants had the poorest contour accuracy, acceptable ease of use, and lowest cost. Preformed mesh implants had intermediate contour accuracy, excellent ease of use, and low cost. Conclusion All 3 techniques provide equivalent orbital volume correction. However, preformed mesh implants have many advantages based on contour accuracy, ease of use, and relative cost.

Validation of the pharyngeal squeeze maneuver.

Objective: The pharyngeal squeeze maneuver (PSM) is a surrogate measure of pharyngeal strength on endoscopy. The validity of this measure has not been reported. The purpose of this investigation was to evaluate the validity of the PSM. Study Design: Case series with planned data collection. Subjects and Methods: Simultaneous endoscopic and fluoroscopic swallow evaluations were performed on a cohort of individuals with dysphagia. The PSM was compared to a validated measure of pharyngeal strength, the pharyngeal constriction ratio (PCR). An elevated PCR indicates a weakened pharynx. Results: The mean PCR for subjects with an intact PSM was 0.06 (± 0.08), compared to a mean PCR of 0.31 (± 0.20) for individuals with an absent PSM. The PCR was significantly higher, indicating a weaker pharynx, in persons with an absent PSM (P < 0.001). Conclusions: The PCR is elevated in persons with a diminished pharyngeal squeeze. These data suggest the pharyngeal squeeze maneuver is a valid surrogate measure of pharyngeal motor integrity.

Computer-aided analysis of orbital volume: a novel technique.

Objective: To demonstrate the accuracy and efficiency of a novel software tool designed specifically for volumetric analysis of the orbit. Methods: The software was evaluated for accuracy and speed in analysis of orbital CT data sets. The analysis included: 1) intraoperator error: one operator repeatedly evaluated a single orbit multiple times. The variation in volumes was compared; 2) interoperator error: 3 operators evaluated the same orbits multiple times. The variation in volume measurements among operators was compared; 3) interscan error: one operator evaluated the volume of single orbit scanned on multiple occasions by different CT scanners. The variation in volume measurements among scans performed at different times was compared; and 4) time for analysis: one operator evaluated 52 orbits, recording the time it took to analyze each orbit. Results: Intraoperator error was 0.08 cc (95% confidence interval, 0.06–0.10). Interoperator error was 0.18 cc (95% confidence interval, 0.14–0.20). Interscan variability data showed a trend toward increasing error for repeated patient scans using different CT scanners. Average time for analysis of single orbit was 138 seconds (standard deviation = 24; range, 95–217 seconds). Conclusions: Maxillo is an accurate and efficient tool for semiautomatic evaluation of orbital volume in nontraumatized orbits.

Evaluating risk factors and predicting complications in head and neck reconstructive surgery.

Purpose of reviewComplications in head and neck reconstructive surgery can have devastating effects. There is a tremendous body of literature examining risk factors that may predict complications in this patient population, thereby minimizing or avoiding adverse outcomes. Recent findingsRotational thromboelastometry may provide a mechanism to predict coagulopathy in patients undergoing microvascular reconstruction. Surveillance of serum C-reactive protein levels may provide an additional tool for early intervention in wound complications Controversy persists in the literature regarding specific risk factors and associated perioperative complications. SummaryPerioperative medical and surgical complications are commonplace in the management of complex oncologic disease and attendant defect reconstructions. Potential risk factors have been examined exhaustively in the literature without a consensus being established.

Additive manufacturing technology in reconstructive surgery.

Purpose of reviewTechnological advances have been part and parcel of modern reconstructive surgery, in that practitioners of this discipline are continually looking for innovative ways to perfect their craft and improve patient outcomes. We are currently in a technological climate wherein advances in computers, imaging, and science have coalesced with resulting innovative breakthroughs that are not merely limited to improved outcomes and enhanced patient care, but may provide novel approaches to training the next generation of reconstructive surgeons. Recent findingsNew developments in software and modeling platforms, imaging modalities, tissue engineering, additive manufacturing, and customization of implants are poised to revolutionize the field of reconstructive surgery. SummaryThe interface between technological advances and reconstructive surgery continues to expand. Additive manufacturing techniques continue to evolve in an effort to improve patient outcomes, decrease operative time, and serve as instructional tools for the training of reconstructive surgeons.

S194 – Pharyngeal Thickness in Young and Elderly Normal Subjects

Objectives Previous research has demonstrated pharyngeal size and constriction differences between normal young and elderly adults. Evidence suggests that the pharynx of elderly subjects dilates and does not constrict as well as younger persons. The distance between the larynx and the hyoid at rest is greater in the elderly, as is the anterior-posterior width of the pharynx maximally expanded. We have noticed that the pharynx of elderly persons appears to atrophy with age. The purpose of this investigation was to compare pharyngeal wall thickness in young vs. elderly persons. Methods Videofluoroscopic swallow studies were performed on 82 normal adults under the age of 65 years and on 89 normal adults over the age of 65. Measures of posterior pharyngeal wall thickness (PWT) were determined at rest and at the same point during maximum constriction of the pharynx on a 20-cc bolus swallow. Data were compared with the independent samples t-test. Results No gender differences were identified for the younger or elderly groups. Mean PWT at rest was .40cm (± .08) for the younger group and 30cm (± .08) for the elderly (p <0.01). Pharyngeal wall thickness measured at the same point during maximum constriction was 1.08cm (±38) for the younger group and .92cm (±36) for the elderly (p <0.01). Conclusions Data from the current study suggest that the posterior pharyngeal wall is thinner in elderly individuals older than 65 as compared to younger adults. These differences may help explain differences in pharyngeal strength, swallowing efficiency, and safety in the elderly.

The Validity of the Pharyngeal Squeeze Maneuver

Objective Pharyngeal strength is essential for safe bolus transit during deglutition. The pharyngeal squeeze maneuver (PSM) is a surrogate measure of pharyngeal strength determined on endoscopic swallow evaluation (FEES). Although several investigations have utilized the PSM, the validity of this diagnostic assessment has never been tested. The purpose of this investigation was to evaluate the clinical validity of the PSM. Methods Simultaneous FEES and fluoroscopic swallow evaluations were prospectively performed on 30 consecutive patients being evaluated for dysphagia. The PSM was assessed on all patients and compared to a validated measure of pharyngeal strength on fluoroscopy, the pharyngeal constriction ratio (PCR). As pharyngeal strength diminishes, the PCR increases. The PCR in patients with an intact PSM was compared to the PCR in persons with an absent PSM, with the independent samples t-test and confirmed with the non-parametric Mann-Whitney test. Results 29 simultaneous FEES-fluoroscpic swallow studies were performed. 75% (22/29) had an intact PSM and 25% (7/9) had an absent PSM. The mean PRC for the group with an intact PSM was 0.06 (± 0.08), compared to a mean PCR of 0.31 (± 0.20) for individuals with an absent PSM. The PCR was significantly higher, indicating a weaker pharynx, in persons with an absent PSM (p < 0.001). Conclusions Pharyngeal strength, as assessed with the PCR, is significantly weaker in persons with an absent PSM. These data suggest that the PSM is a valid surrogate measure of pharyngeal motor integrity.