John F. Teichgraeber

Accuracy of a computer-aided surgical simulation protocol for orthognathic surgery: A prospective multicenter study

PURPOSE The purpose of this prospective multicenter study was to assess the accuracy of a computer-aided surgical simulation (CASS) protocol for orthognathic surgery. MATERIALS AND METHODS The accuracy of the CASS protocol was assessed by comparing planned outcomes with postoperative outcomes of 65 consecutive patients enrolled from 3 centers. Computer-generated surgical splints were used for all patients. For the genioplasty, 1 center used computer-generated chin templates to reposition the chin segment only for patients with asymmetry. Standard intraoperative measurements were used without the chin templates for the remaining patients. The primary outcome measurements were the linear and angular differences for the maxilla, mandible, and chin when the planned and postoperative models were registered at the cranium. The secondary outcome measurements were the maxillary dental midline difference between the planned and postoperative positions and the linear and angular differences of the chin segment between the groups with and without the use of the template. The latter were measured when the planned and postoperative models were registered at the mandibular body. Statistical analyses were performed, and the accuracy was reported using root mean square deviation (RMSD) and the Bland-Altman method for assessing measurement agreement. RESULTS In the primary outcome measurements, there was no statistically significant difference among the 3 centers for the maxilla and mandible. The largest RMSDs were 1.0 mm and 1.5° for the maxilla and 1.1 mm and 1.8° for the mandible. For the chin, there was a statistically significant difference between the groups with and without the use of the chin template. The chin template group showed excellent accuracy, with the largest positional RMSD of 1.0 mm and the largest orientation RMSD of 2.2°. However, larger variances were observed in the group not using the chin template. This was significant in the anteroposterior and superoinferior directions and the in pitch and yaw orientations. In the secondary outcome measurements, the RMSD of the maxillary dental midline positions was 0.9 mm. When registered at the body of the mandible, the linear and angular differences of the chin segment between the groups with and without the use of the chin template were consistent with the results found in the primary outcome measurements. CONCLUSIONS Using this computer-aided surgical simulation protocol, the computerized plan can be transferred accurately and consistently to the patient to position the maxilla and mandible at the time of surgery. The computer-generated chin template provides greater accuracy in repositioning the chin segment than the intraoperative measurements.

New Clinical Protocol to Evaluate Craniomaxillofacial Deformity and Plan Surgical Correction

Cranio-Maxillofacial Surgery (CMF) involves the correction of congenital and acquired conditions of the head and face. In the United States, a significant number of patients require surgery for these types of conditions. They include patients with of congenital and developmental deformities of the CMF region (17 million) 1-7, defects after tumor ablation (28,000 new patients per year)8, post-traumatic defects (200,000 per year)9, 10 and deformities of the temporomandibular joint (6000 patients per year require prosthetic and autogenous TMJ reconstruction)11, 12. The latest figures indicate that 33,000 US servicemen and women have been wounded in action in both Operation Iraqi Freedom and Operation Enduring Freedom.13 It is estimated the one fourth to one third of them suffered head and neck injuries.14 The surgical correction of CMF deformities is among the most challenging. The success of these surgeries depends not only on the technical aspects of the operation, but also, to a larger extent, on the formulation of a precise surgical plan.15-24 Over the last 50 years, there have been significant improvements in the technical aspects of surgery, i.e. rigid fixation, resorbable materials, distraction osteogenesis, minimally invasive approaches, etc. However, the planning methods have mostly remained unchanged.17, 18, 20, 24 It is clear that many of the unwanted surgical outcomes are the result of deficient planning. The need to improve the traditional surgical planning methods has led our group to develop a 3D computer-aided surgical simulation (CASS) system to plan CMF surgery. We have utilized this system in maxillofacial surgery23, 25-27, craniofacial surgery28, trauma, distraction osteogenesis28-30 and TMJ reconstruction31. Using this system, a doctor can perform “virtual surgery” and create a 3D prediction of the patients surgical outcomes, as if they are performing surgery in the operating room. We have documented the clinical feasibility18, 24, the accuracy32 and cost-effectiveness33 of this system. Our CASS system incorporates 3 distinctive features and innovations: 1) multiple imaging modalities are used to create an accurate model of the craniofacial skeleton; 2) special techniques are employed to orient the computerized bone model in the natural head position (NHP); and 3) Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) techniques are used to fabricate accurate surgical splints and templates to transfer the surgical plan to the operating room. The purpose of this article is to present our CASS planning protocol.

Changing patterns in the epidemiology and treatment of zygoma fractures: 10-year review.

A ten year retrospective review of 259 zygoma fractures is presented to highlight changes in epidemiology and treatment. Motor vehicle-related trauma resulted in a majority of the injuries (80.6%), with a high incidence of multiple facial fractures (43.2%). The number of zygomatic and other facial fractures decreased over the duration of the study (by 50.0% and 20.1%, respectively, p < 0.05), perhaps reflecting lowered speed limits and the increased use of seat belts. The proportion of fractures receiving open reduction and internal fixation (ORIF) remained relatively constant (46.3%). At present, miniplate fixation is the preferred surgical treatment, accounting for 61.5% of cases in 1988 and 1989. There was a trend toward the use of multiple fixation sites and more frequent use of the lateral maxillary buttress (20.0% increase over the study period). The need for orbital floor exploration decreased by almost half, possibly reflecting improved preoperative radiologic evaluation. Despite the recent popularity of cranial bone grafting for facial reconstruction, silicone rubber was the preferred material for orbital floor repair (59.6% of cases). Although overall surgical complications were few (1.5%) there was a high incidence of associated ocular injuries (36.3%).

Nonsurgical treatment of deformational plagiocephaly: a systematic review

OBJECTIVE To evaluate and summarize the evidence comparing nonsurgical therapies in the treatment of infants with deformational plagiocephaly. DATA SOURCES Scientific articles and abstracts published in English between January 1978 and August 2007 were searched from 5 online literature databases, along with a manual search of conference proceedings. STUDY SELECTION Studies were selected and appraised for methodological quality by 2 reviewers independently using a Critical Appraisal Skills Programme form (cohort criteria). INTERVENTIONS Molding helmet therapy vs head repositioning therapy. MAIN OUTCOME MEASURE Success rate of the treatment. RESULTS A total of 3793 references were retrieved. There were no randomized controlled trials. Only 7 cohort studies met the inclusion criteria. Five of the 7 studies presented evidence that molding therapy is more effective than repositioning, even with the biases favoring the repositioning groups. In the molding groups, the asymmetry was more severe and the infants were older. The infants who failed to respond to repositioning therapy were also switched to molding therapy. The treatment outcomes from the other 2 studies were difficult to assess because of flaws in their study design. Finally, the relative improvement of using molding therapy was calculated from one study. It was about 1.3 times greater than with repositioning therapy. CONCLUSION The studies showed considerable evidence that molding therapy may reduce skull asymmetry more effectively than repositioning therapy. However, definitive conclusions on the relative effectiveness of these treatments were tempered by potential biases in these studies. Further research is warranted.

Presurgical nasoalveolar molding therapy for the treatment of bilateral cleft lip and palate : A preliminary study

Objective: To evaluate the outcome of presurgical nasoalveolar molding (PNAM) therapy in the treatment of patients with nonsyndromic unilateral cleft and palate (UCLP). Design: A prospective study with blinded measurements. Patients: Twelve patients with UCLP treated from 1997 to 2003. Interventions: The starting age for PNAM therapy was 26 days and the average length of the therapy was 110 days. Main Outcome Measures: Measurements of intraoral and extraoral casts were made, and statistical analyses were used to compare the differences between pre- and posttherapy measurements. Results: After PNAM therapy, there was a statistically significant decrease in both intersegment alveolar cleft distance and columellar deviation (p < .05). There was also a statistically significant increase in cleft nostril height, maxillary width, and columellar width (p < .05). Moreover, although there was no statistically significant reduction of the affected nostril width, it demonstrated on average 1.7-mm reduction after PNAM therapy. The length of the time the patient utilized the appliance and postmolding nostril height were found to have a statistically significant positive correlation (p < .05). Conclusions: PNAM therapy decreases intersegment alveolar cleft distance while permitting an increase in posterior maxillary arch width. It also increases nasal symmetry by decreasing columellar deviation, increasing nostril height on the affected side, maintaining bialar width of nose, increasing columellar width, and creating more symmetrical nostril heights and widths. The improvement of the height of the cleft nostril was correlated with the time the appliance was applied.

Three-dimensional surgical planning for maxillary and midface distraction osteogenesis.

Computerized surgical planning protocols for distraction osteogenesis are still in their rudimentary phase. The authors have developed a system to plan distraction osteogenesis in craniofacial and maxillofacial surgery that uses three-dimensional computed tomography scans and computer simulation in a virtual reality environment. This involves the creation of a three-dimensional bone model of the craniofacial skeleton, which incorporates virtual globes. Virtual osteotomies are performed on the bone model and the movements of the bone segments are simulated. The program generates a recipe for the linear and the angular changes necessary to achieve the desired outcome. The purpose of this article is to present this surgical planning process and discuss its use in maxillary and midface distraction.

Outcome Study of Computer-Aided Surgical Simulation in the Treatment of Patients with Craniomaxillofacial Deformities

PURPOSE The purpose of this study was to determine whether the surgical outcomes achieved with computer-aided surgical simulation (CASS) are better than those achieved with traditional methods. MATERIALS AND METHODS Twelve consecutive patients with craniomaxillofacial (CMF) deformities were enrolled. According to the CASS clinical protocol, a 3-dimensional computer composite skull model for each patient was generated and reoriented to the neutral head posture. These models underwent 2 virtual surgeries: 1 was based on CASS (experimental group) and the other was based on traditional methods 1 year later (control group). Once the 2 virtual surgeries were completed, 2 experienced oral and maxillofacial surgeons at 2 different settings evaluated the 2 surgical outcomes. They were blinded to the planning method used on the virtual models and each others evaluation results. The primary outcome was overall CMF skeletal harmony. The secondary outcomes were individual maxillary, mandibular, and chin harmonies. Statistical analyses were performed. RESULTS Overall CMF skeletal harmony achieved with CASS was statistically significantly better than that achieved with traditional methods. In addition, the maxillary and mandibular surgical outcomes achieved with CASS were significantly better. Furthermore, although not included in the statistical model, the chin symmetry achieved by CASS tended to be better. A regression model was established between mandibular symmetry and overall CMF skeletal harmony. CONCLUSION The surgical outcomes achieved with CASS are significantly better than those achieved with traditional planning methods. In addition, CASS enables the surgeon to better correct maxillary yaw deformity, better place proximal/distal segments, and better restore mandibular symmetry. The critical step in achieving better overall CMF skeletal harmony is to restore mandibular symmetry.

Molding helmet therapy in the treatment of brachycephaly and plagiocephaly.

The purpose of this study was to compare the use of molding helmet therapy in the treatment of positional brachycephaly and posterior positional plagiocephaly. Four hundred twenty-eight children with positional brachycephaly or plagiocephaly were included in this study. In this group of patients, 132 (32%) were treated with positioning alone. Of the 292 (68%) patients who were treated with molding therapy, 64 (21.9%) were treated for positional brachycephaly and 248 (78.1%) were treated for posterior positional plagiocephaly. All children were evaluated by a craniofacial surgeon and a pediatric neurosurgeon. Anthropomorphic measurements were used to assess the efficacy of treatment. Measurements were made before initiation of therapy and at 2-month intervals until the completion of therapy. Results showed that statistically significant improvements (P < 0.01) were seen in all patients treated with molding helmet therapy. Overall, the children with posterior plagiocephaly normalized their head shapes; however, the head shapes of the children with positional brachycephaly did not normalize despite statistically significant improvements in their Cephalic Index. It is concluded that molding helmet therapy is an effective treatment of position-induced head shape abnormalities. Helmet therapy is more effective in children with posterior positional plagiocephaly than in children with positional brachycephaly.

Deformational Posterior Plagiocephaly: Diagnosis and Treatment

OBJECTIVE This study was designed to evaluate the effectiveness of helmet therapy (DOC band) in the correction of patients with moderate to severe posterior deformational plagiocephaly. DESIGN In this prospective study, the infants were evaluated using 18 anthropometric measurements. PATIENTS The charts of 248 patients seen between August 1, 1995, and July 31, 1999, were reviewed, and 125 met the criteria for inclusion in the study. All the patients had posterior deformational plagiocephaly with no other craniofacial deformities or medical conditions. Treatment was instituted prior to 1 year of age, and all patients were compliant with DOC band usage and had complete anthropometric measurements. RESULTS The study recorded a 41.56% (p < .001) reduction in cranial vault asymmetry and a 40.23% (p <.001) reduction in cranial base asymmetry. Orbitotragial asymmetry was improved 18.72% (p = .0738). The age at which treatment was begun was not a significant factor in predicting treatment outcomes.

New 3-Dimensional Cephalometric Analysis for Orthognathic Surgery

Two basic problems have been associated with traditional 2-dimensional cephalometry. First, many important parameters cannot be measured on plain cephalograms; and second, most 2-dimensional cephalometric measurements are distorted in the presence of facial asymmetry. Three-dimensional cephalometry, which has been facilitated by the introduction of cone-beam computed tomography, can solve these problems. However, before this can be realized, fundamental problems must be solved. These include the unreliability of internal reference systems and some 3-dimensional measurements, and the lack of tools to assess and measure the symmetry. In the present report, we present a new 3-dimensional cephalometric analysis that uses different geometric approaches to solve these fundamental problems. The present analysis allows the accurate measurement of the size, shape, position, and orientation of the different facial units and incorporates a novel method to measure asymmetry.