Faculty Bibliography

We present a method for the efficient processing of contact and collision in volumetric elastic models simulated using the Projective Dynamics paradigm. Our approach enables interactive simulation of tetrahedral meshes with more than half a million elements, provided that the model satisfies two fundamental properties: the region of the model's surface that is susceptible to collision events needs to be known in advance, and the simulation degrees of freedom associated with that surface region should be limited to a small fraction (e.g. 5%) of the total simulation nodes. In such scenarios, a partial Cholesky factorization can abstract away the behaviour of the collision-safe subset of the face model into the Schur Complement matrix with respect to the collision-prone region. We demonstrate how fast and accurate updates of bilateral penalty-based collision terms can be incorporated into this representation, and solved with high efficiency on the GPU. We also demonstrate iterating a partial update of the element rotations, akin to a selective application of the local step, specifically on the smaller collision-prone region without explicitly paying the cost associated with the rest of the simulation mesh. We demonstrate efficient and robust interactive simulation in detailed models from animation and medical applications.

Background/Purpose: The evolution of primary unilateral cleft lip repair represents a series of incremental modifications pioneered by a distinct group of master surgeons. It is through understanding the purpose of each evolutionary step, the limits and compromises of these steps, and the subsequent modifications which followed, can a greater understanding of the art of cleft lip repair be realized. This course will trace the conceptual development of unilateral cleft lip repair over the past 70 years using a novel, real-time computer-based cleft lip simulator. A first order accurate biophysics implementation within the simulator will be used to demonstrate the cleft lip repair techniques described to reveal the strengths and weaknesses of each stage of unilateral lip repair development. The course will begin with the Tennison Randall lower triangular lip repair, as it is still in common use today. This will be followed by Skoog, Wynn, and Mustarde adding an upper triangle to the lip repair. The various stages in the progression of the Millard repair will then be carefully traced along with the biophysics which are likely responsible for why Millard altered his original design. The modifications of the Millard design by other surgeons, and the reasons for them, will then be carefully traced. The modifications covered will be those of Noordhoff, Mohler, Cutting, Fisher, and others. The interaction between lip repair technique and primary correction of the cleft-lip nasal deformity will be discussed in detail. Simulator-based demonstrations will be augmented with patient examples from the senior author's clinical practice which illustrate the conceptual difficulties encountered at various stages in the historical development of primary unilateral cleft lip and nose repair. Methods/Description: The principal method used in this course will be real-time computer-based surgical simulation. A unilateral cleft lipnose model involving skin, mucosa, muscle, bone, cartilage, and teeth was derived from an MR scan of an adolescent with an unrepaired unilateral cleft. Alterations in the model are illustrated with first-order accurate biophysics using a new software base called projective dynamics. Surgical tools provided are scalpel, suture, hook, and undermine of both skin/mucosa and bone/cartilage. Surgical "'history" files are used to step through a succession of cleft lip repairs in the surgical eclectic. The presentation will be augmented with photographs from the senior author's long career further illustrating why successive alterations in technique were made

Background/Purpose: We present the first long-term outcomes analysis of the nasoalveolar molding (NAM) treatment protocol on patients with a cleft followed from birth to facial maturity. Methods/Description: Single-institution retrospective review of all patients with a cleft who underwent NAM between the years 1990 and 2000. All study patients completed cleft care treatment at the same institution and were followed by the same team members. Our institution's treatment protocol offers NAM to patients with a significant cleft nasal deformity and/or widely displaced alveolar segments. All patients underwent primary cleft lip and nasal repair prior to the age of 6 months. Gingivoperiosteoplasty (GPP) is performed, when possible, at the time of lip repair. Cleft palate repair is performed by 1 year of age. Collected data include surgical and orthodontic outcomes of cleft care such as cleft lip and palate repair, GPP, alveolar bone grafting (ABG), speech surgery for velopharyngeal insufficiency (VPI), palatal fistula repairs, orthognathic surgery, and revision surgery to the nose and/or lip.
Result(s): A total of 135 patients met the inclusion criteria. Mean length of follow-up was 18.8 years. Eighty-nine patients presented with a unilateral cleft (UNI) and 46 with a bilateral cleft (BI); 84% (113/135) of patients underwent GPP (UNI: 78% [69/89]; BI: 96% [44/46]), 43% (58/135) of patients underwent ABG (UNI: 40% [36/89]; BI: 48% [22/46]), 18% (24/135) of patients underwent speech surgery for VPI (UNI: 14% [12/89]; BI: 26% [12/46]), 3% (4/135) of patients underwent palatal fistula repair (UNI: 0% [0/89]; BI: 9% [4/46]), 31% (42/135) underwent orthognathic surgery (UNI: 22% [20/89]; BI: 48% [22/46]), and 11% (15/135) underwent revision surgery to lip, nose, or both prior to facial maturity (UNI: 9% [8/89]; BI: 15% [7/46]]. Of the patients who underwent GPP, 61% (69/113) did not require ABG (UNI: 65% [45/69]; BI: 55% [24/44]) and 42% (48/113) required neither ABG nor orthognathic surgery (UNI: 51% [35/69]; BI: 30% [13/44]).
Conclusion(s): Clinical outcomes of the NAM treatment protocol from birth to facial maturity demonstrate a low rate of revision surgery to the lip and nose, as well as a low fistula and VPI rate. The frequency of orthognathic surgery reported in this study is consistent with published data. In addition, 42% of patients who underwent NAM with GPP required neither ABG nor orthognathic surgery

OBJECTIVES/OBJECTIVE:To compare 3-dimensional nasal symmetry in patients with UCLP who had either rotation advancement alone or nasoalveolar molding (NAM) followed by rotation advancement in conjunction with primary nasal repair. DESIGN/METHODS:Pilot retrospective cohort study. MATERIALS AND METHODS/METHODS:Nasal casts of 23 patients with UCLP from 2 institutions were analyzed; 12 in the rotation advancement only group (Iowa) and 11 in the NAM, rotation advancement with primary nasal repair group (New York). Casts from patients aged 6 to 18 years were scanned using the 3Shape scanner and 3-dimensional analysis of nasal symmetry performed using 3dMD Vultus software, Version 2507, 3dMD, Atlanta, GA. Cleft and noncleft side columellar height, nasal dome height, alar base width, and nasal projection were linearly measured. Inter- and intragroup analyses were performed using t tests and paired t tests as appropriate. RESULTS:; P = .02). Intergroup analysis performed on the most sensitive linear measure, alar base width, revealed significantly less asymmetry on average in group 2 than in group 1 ( P = .013). CONCLUSION/CONCLUSIONS:This study suggests the NAM followed by rotation advancement in conjunction with primary nasal repair approach may result in less nasal asymmetry compared to rotation advancement alone.

BACKGROUND:In October 2012, a freely available, internet-based cleft simulator was created in partnership between academic, nonprofit, and industry sectors. The purpose of this educational resource was to address global disparities in cleft surgery education. This report assesses demographics, usage, and global effect of our simulator, in its fifth year since inception. OBJECTIVE:Evaluate the global effect, usage, and demographics of an internet-based educational digital simulation cleft surgery software. SETTING AND PARTICIPANTS/METHODS:Simulator modules, available in five languages demonstrate surgical anatomy, markings, detailed procedures, and intraoperative footage to supplement digital animation. Available data regarding number of users, sessions, countries reached, and content access were recorded. Surveys evaluating the demographic characteristics of registered users and simulator use were collected by direct e-mail. RESULTS:The total number of simulator new and active users reached 2865 and 4086 in June 2017, respectively. By June 2017, users from 136 countries had accessed the simulator. From 2015 to 2017, the number of sessions was 11,176 with a monthly average of 399.0 ± 190.0. Developing countries accounted for 35% of sessions and the average session duration was 9.0 ± 7.3 minutes. This yields a total simulator screen time of 100,584 minutes (1676 hours). Most survey respondents were surgeons or trainees (87%) specializing in plastic, maxillofacial, or general surgery (89%). Most users found the simulator to be useful (88%), at least equivalent or more useful than other resources (83%), and used it for teaching (58%). CONCLUSIONS:Our internet-based interactive cleft surgery platform reaches its intended target audience, is not restricted by socioeconomic barriers to access, and is judged to be useful by surgeons. More than 4000 active users have been reached since inception. The total screen time over approximately 2 years exceeded 1600 hours. This suggests that future surgical simulators of this kind may be sustainable by stakeholders interested in reaching this target audience.

A retrospective Institutional Review Board-approved review was performed at the Institute of Reconstructive Plastic Surgery, NYU Langone Medical Center, of patients undergoing craniofacial distraction osteogenesis procedures using the rigid external distractor device between 2000 and 2010. Three particularly challenging cases were identified and are presented here.

INTRODUCTION/BACKGROUND:Parallel to worldwide disparities in patient access to health care, the operative opportunities of surgical trainees are increasingly restricted across the globe. Efforts have been directed toward enhancing surgical education outside the operating room and reducing the wide variability in global trainee operative experience. However, high costs and other logistical concerns may limit the reproducibility and sustainability of nonoperative surgical education resources. METHODS:A partnership between the academic, nonprofit, and industry sectors resulted in the development of an online virtual surgical simulator for cleft repair. First year global access patterns were observed. RESULTS:The simulator is freely accessible online and includes 5 normal and pathologic anatomy modules, 5 modules demonstrating surgical markings, and 7 step-by-step procedural modules. Procedural modules include high-definition intraoperative footage to supplement the virtual animation in addition to include multiple-choice test questions. In its first year, the simulator was accessed by 849 novel users from 78 countries; 70% of users accessed the simulator from a developing nation. CONCLUSION/CONCLUSIONS:The Internet shows promise as a platform for surgical education and may help address restrictions and reduce disparities in surgical training. The virtual surgical simulator presented may serve as the foundation for the development of a global curriculum in cleft repair.

BACKGROUND:Gingivoperiosteoplasty can avoid secondary alveolar bone grafting in up to 60 percent of patients with a cleft. However, preoperative predictors of success have not been characterized. This study reports on the preoperative alveolar segment position most favorable for successful gingivoperiosteoplasty. METHODS:The authors performed a single-institution, retrospective review of patients with a unilateral cleft who underwent nasoalveolar molding. Alveolar segment morphology was directly measured from maxillary dental models created before and after nasoalveolar molding. Statistical analysis was performed to identify parameters associated with the decision to perform gingivoperiosteoplasty and its success, defined as the absence of an eventual need for alveolar bone grafting. RESULTS:Fifty patients with a unilateral cleft who received nasoalveolar molding therapy were included in this study (40 underwent gingivoperiosteoplasty and 10 did not). Eighteen alveolar morphology and position characteristics were tested, including cleft gap width, horizontal and vertical positions of the alveolar segments, alveolar stepoff, and degree of alveolar segment apposition. Post-nasoalveolar molding vertical rotation of the greater segment and the percentage of segment alignment in the correct anatomical zone were statistically significant predictors of the decision to perform gingivoperiosteoplasty (86 percent predictive power). Cleft gap, greater/lesser segment overlap, alveolar segment alignment, greater segment horizontal rotation, and alveolar segment width following nasoalveolar molding were significant predictors of gingivoperiosteoplasty success (86.5 percent predictive power). CONCLUSIONS:Greater segment vertical rotation and proper alveolar segment anatomical alignment are positive predictors of the decision to perform gingivoperiosteoplasty. Post-nasoalveolar molding evidence of proper alignment and direct contact between the alveolar segments were significant predictors of successful gingivoperiosteoplasty. CLINICAL QUESTION/LEVEL OF EVIDENCE/METHODS:Risk, III.

Contemporary plastic surgery residents are increasingly challenged to learn a greater number of complex surgical techniques within a limited period. Surgical simulation and digital education resources have the potential to address some limitations of the traditional training model, and have been shown to accelerate knowledge and skills acquisition. Although animal, cadaver, and bench models are widely used for skills and procedure-specific training, digital simulation has not been fully embraced within plastic surgery. Digital educational resources may play a future role in a multistage strategy for skills and procedures training. The authors present two virtual surgical simulators addressing procedural cognition for cleft repair and craniofacial surgery. Furthermore, the authors describe how partnerships among surgical educators, industry, and philanthropy can be a successful strategy for the development and maintenance of digital simulators and educational resources relevant to plastic surgery training. It is our responsibility as surgical educators not only to create these resources, but to demonstrate their utility for enhanced trainee knowledge and technical skills development. Currently available digital resources should be evaluated in partnership with plastic surgery educational societies to guide trainees and practitioners toward effective digital content.