Evaluation of a high-fidelity cleft alveolar bone graft simulator

INTRODUCTION

Cleft alveolar bone graft surgery is technically challenging to perform as well as difficult to learn and teach. A high-fidelity cleft alveolar bone graft simulator was previously developed. However, further evaluation of the simulator is necessary to assess its efficacy.

METHODS

Two cleft simulation workshops were conducted in which participants were led through a simulated cleft alveolar bone graft. The first simulation workshop involved six plastic surgery trainees. The second workshop involved 43 practicing cleft surgeons. The participants were provided with a Likert-type questionnaire assessing the simulators' features, realism, and value as a training tool. The change in self-reported confidence was assessed by providing each participant with a pre- and post-simulation confidence questionnaire.

RESULTS

There was overall agreement in the realism of the simulators' features (average score of 4.67 and 3.80 out of 5 for the trainees and surgeons, respectively). There was overall agreement to strong agreement in the simulators value as a training tool (average score of 5 and 4.43 out of 5 for the trainees and surgeons, respectively). The self-reported confidence increased for all questionnaire items for both the trainees and surgeons. This was significant (p < 0.05) for five out of eight and all questionnaire items for the trainees and surgeons, respectively. The magnitude of the confidence increase was generally greater for less experienced participants.

CONCLUSION

The cleft alveolar bone graft simulator was found to be realistic and valuable as a training platform. Use of the simulator improved self-reported confidence in cleft alveolar bone graft surgery.

Development and Evaluation of a High-Fidelity Rhinoplasty Simulator

SUMMARY

Rhinoplasty is a challenging procedure with a steep learning curve. Surgical simulators provide a safe platform to gain hands-on experience without compromising patient outcomes. Therefore, rhinoplasty is an ideal procedure to benefit from an effective surgical simulator. A high-fidelity rhinoplasty simulator was developed using three-dimensional computer modeling, three-dimensional printing, and polymer techniques. The simulator was tested by six surgeons with experience in rhinoplasty to assess realism, anatomic accuracy, and value as a training tool. The surgeons performed common rhinoplasty techniques and were provided a Likert-type questionnaire assessing the anatomic features of the simulator. A variety of surgical techniques were performed successfully using the simulator, including open and closed approaches. Bony techniques performed included endonasal osteotomies and rasping. Submucous resection with harvest of septal cartilage, cephalic trim, and tip suturing, as well as grafting techniques including alar rim, columellar strut, spreader, and shield grafts, were performed successfully. Overall, there was agreement on the simulator's anatomic accuracy of bony and soft-tissue features. There was strong agreement on the simulator's overall realism and value as a training tool. The simulator provides a high-fidelity, comprehensive training platform to learn rhinoplasty techniques to augment real operating experience without compromising patient outcomes.

Bilateral Cleft lip Simulation

OBJECTIVE

To evaluate the features, anatomic accuracy, and educational value of a high-fidelity bilateral cleft lip simulator.

DESIGN

Evaluation of the simulator by expert cleft surgeons after performing a simulated bilateral cleft lip repair.

SETTING

The simulator was evaluated by the surgeons during the Latin American Craniofacial Association meeting.

PARTICIPANTS

Eleven experienced cleft surgeons evaluated the simulator. The cleft surgeons were selected based on their availability during the meeting.

INTERVENTIONS

The participants performed a simulated bilateral cleft lip repair. They were each provided with a questionnaire assessing the simulator's features, realism and value as a training tool.

MAIN OUTCOME MEASURE (S)

The main outcome measure are the scores obtained from a Likert-type questionnaire assessing the simulators features, realism and value.

RESULTS

Overall, the surgeons agreed with the simulator's realism and anatomic accuracy (average score of 3.7 out of 5). Overall, the surgeons strongly agreed with the value of the simulator as a training tool (average score of 4.6 out of 5).

CONCLUSIONS

A high-fidelity bilateral cleft lip simulator was developed that is realistic and valuable as a training tool. The simulator provides a comprehensive training platform to gain hands-on experience in bilateral cleft lip repair before operating on real patients.

The First Alveolar Bone Graft Simulator

Alveolar bone graft (ABG) surgery in cleft patients is technically challenging. The procedure requires design, dissection and release of soft tissue flaps to create a seal around the bone graft. In addition, visualization during the procedure is challenging within the confines of the cleft. These features make ABG surgery difficult to learn and teach, and it is, therefore, a suitable procedure for the use of a simulator. A high-fidelity cleft ABG simulator was developed using three-dimensional printing, polymer, and adhesive techniques. Simulated ABG surgery was performed by two expert cleft surgeons for a total of five simulation sessions to test the simulator's features and the ability to perform the critical steps of an ABG. ABG surgery was successfully performed on the simulator. The simulations involved interacting with realistic dissection planes as well as multi-layered synthetic soft (periosteum, mucosa, gingiva, adipose tissue) and hard (teeth, bone) tissue. The simulator allowed performance of cleft marginal incisions, dissection, and elevation of a muco-gingival-periosteal flap, creation of nasal upturned and palatal downturned flaps, nasal and palatal side closure, insertion of simulated bone graft material, and advancement of the muco-gingival-periosteal flap for closure of the anterior wall of the cleft. The ABG simulator allowed performance of the critical steps of ABG surgery. This is the first ABG simulator developed, which incorporates the features necessary to practice the procedure from start to finish.

Frontal Sinus Fractures

Management of frontal sinus fractures is controversial with no universally accepted treatment protocol. Goals of management are to correct aesthetic deformity, preserve sinus function when it is deemed salvageable, prevent sequela related to the injury, and minimize complications associated with intervention. Studies suggest that frontal sinus injuries, including disruption of the nasofrontal outflow tract (NFOT), can be managed nonoperatively in many cases. Advances in the utilization of endoscopic techniques have led to an evolution in management that reduces the need for open procedures, which have increased morbidity compared with endoscopic approaches. We employ a minimally disruptive protocol that treats the majority of fractures nonoperatively with serial clinical and radiographic examinations to assess for sinus aeration. Surgical intervention is reserved for the most severely displaced and comminuted posterior table fractures and unsalvageable NFOTs utilizing endoscopic approaches whenever possible.

Assessing Performance in Simulated Cleft Palate Repair Using a Novel Video Recording Setup

OBJECTIVE

To test the feasibility of implementing a high-fidelity cleft palate simulator during a workshop in Santiago, Chile, using a novel video endoscope to assess technical performance.

DESIGN

Sixteen cleft surgeons from South America participated in a 2-day cleft training workshop. All 16 participants performed a simulated repair, and 13 of them performed a second simulated repair. The repairs were recorded using a low-cost video camera and a newly designed camera mouth retractor attachment. Twenty-nine videos were assessed by 3 cleft surgeons using a previously developed cleft palate objective structured assessment of technical skill (CLOSATS with embedded overall score assessment) and global rating scale. The reliability of the ratings and technical performance in relation to minimum acceptable scores and previous experience was assessed.

RESULTS

The video setup provided acceptable recording quality for the purpose of assessment. Average intraclass correlation coefficient for the CLOSATS, global, and overall performance score was 0.69, 0.75, and 0.82, respectively. None of the novice surgeons passed the CLOSATS and global score for both sessions. One participant in the intermediate group, and 2 participants in the advanced group passed the CLOSATS and global score for both sessions. There were highly experienced participants who failed to pass the CLOSATS and global score for both sessions.

CONCLUSIONS

The cleft palate simulator can be practically implemented with video-recording capability to assess performance in cleft palate repair. This technology may be of assistance in assessing surgical competence in cleft palate repair.

Suitability of Using the Hamate for Reconstruction of the Finger Middle Phalanx Base: An Assessment of Cartilage Thickness

Background

Osteochondral grafts are indicated for reconstructing the finger middle phalanx base when there is greater than 50% involvement of the articular surface and significant comminution. This study aims to compare the cartilage thickness of the distal surface of the hamate to the finger middle phalanx base to assess its suitability as an osteochondral graft.

Methods

A 3-dimensional laser scanner and computer modelling techniques were utilized to determine the cartilage thickness of the distal surface of the hamate, and finger middle phalanx base using cadaver specimens. The mean, maximum, and coefficient of variation (CV%; a measure of uniformity of cartilage distribution), as well as cartilage distribution maps were determined.

Results

The mean cartilage thickness of the hamate was 0.73 ± 0.08 mm compared to the average mean thickness of the finger middle phalanx base of 0.40 ± 0.12 mm. The maximum cartilage thickness of the hamate was 1.27 ± 0.14 mm compared to the average maximum of the finger middle phalanx base of 0.67 ± 0.14 mm. The CV% of the hamate was 27.8 ± 4.2 compared to the average CV% for the finger middle phalanx base of 26.6 ± 8.1. The hamate and finger middle phalanx base have maximum areas that were most frequently at or spanning the median ridge; however, this was more consistently observed with the hamate.

Conclusion

The distal surface of the hamate is a suitable osteochondral graft with respect to cartilage thickness and distribution providing sufficient cartilage for reconstruction of the finger middle phalanx base.

Utilization of Cable Guide Channels for Compact Articulation Within a Dexterous Three Degrees-of-Freedom Surgical Wrist Design

Pin-jointed wrist mechanisms provide compact articulation for surgical robotic applications, but are difficult to miniaturize at scales suitable for small body cavity surgery. Solid surface cable guide channels, which eliminate the need for pulleys and reduce overall length to facilitate miniaturization, were developed within a three-degree-of-freedom cable-driven pin-jointed wrist mechanism. A prototype was 3D printed in steel at 5 mm diameter. Friction generated by the guide channels was experimentally tested to determine increases in cable tension during constant cable velocity conditions. Cable tension increased exponentially from 0 to 37% when the wrist pitched from 0 deg to 90 deg. The shape of the guide channel groove and angle, where the cable exits the channel impacts the magnitude of cable tension. A spring tensioning and cam actuation mechanism were developed to account for changing cable circuit path lengths during wrist pitch. This work shows that pulley-free cable wrist mechanisms can facilitate miniaturization below current feasible sizes while retaining compact articulation at the expense of increases in friction under constant cable velocity conditions.

Economy of Hand Motion During Cleft Palate Surgery Using a High-Fidelity Cleft Palate Simulator

OBJECTIVE

The objectives of this study were to assess economy of hand motion of residents, fellows, and staff surgeons using a high-fidelity cleft palate simulator to (1) stratify performance for the purpose of simulator validation and (2) to estimate the learning curve.

DESIGN

Two residents, 2 fellows, and 2 staff surgeons performed cleft palate surgery on a high-fidelity cleft palate simulator while their hand motion was tracked using an electromagnetic hand sensor. The time, number of hand movements, and path length of their hands were determined for 10 steps of the procedure. The magnitude of these metrics was compared among the 3 groups of participants and utilized to estimate the learning curve using curve-fitting analysis.

RESULTS

The residents required the most time, number of hand movements, and path length to complete the procedure. Although the number of hand movements was closely matched between the fellows and staff, the overall total path length was shorter for the staff. Inverse curves were fit to the data to represent the learning curve and 25 and 113 simulation sessions are required to reach within 5% and 1% of the expert level, respectively.

CONCLUSION

The simulator successfully stratified performance using economy of hand motion. Path length is better matched to previous level of experience compared to time or number of hand movements.

Utilization of a robotic mount to determine the force required to cut palatal tissue

Determination of the material properties of soft tissue is a growing area of interest that aids in the development of new surgical tools and surgical simulators. This study first aims to develop a robot-operated tissue testing system for determination of tissue cutting forces. Second, this system was used to ascertain the cutting properties of the hard and soft palate mucosa and soft palate musculature for the purpose of developing a robotic instrument for cleft palate surgery and a cleft-specific surgical simulator. The palate tissue was cut with a 15 blade mounted to the robot with varying angles (30°, 60°, 90°) and speeds (1.5, 2.5, 3.5 cm/s) of cutting to imitate typical operative tasks. The cutting force range for hard palate mucosa, soft palate mucosa and soft palate muscle were 0.98-3.30, 0.34-1.74 and 0.71-2.71 N, respectively. The break-in force of the cut (i.e. force required for the blade to penetrate the tissue) is significantly impacted by the angle of the blade relative to the tissue rather than the cutting speed. Furthermore, the total surface area of the tissue in contact with the blade during the cut has a significant impact on the total force expended on the tissue.

Ulcerative colitis-linked antineutrophil cytoplasmic antibody in the cotton-top tamarin model of colitis

The presence of antineutrophil cytoplasmic antibodies (ANCA) in serum has recently been shown to be a good disease marker for ulcerative colitis. An animal model of colitis expressing serum ANCA would allow prospective studies of the relationship between ANCA expression and development of colitis. The cotton-top tamarin model of spontaneous colitis was investigated for presence of ANCA to evaluate its potential as a model for the study of the immune response in human ulcerative colitis. Results show that cotton-top tamarin neutrophils have antigens recognized by immunoglobulin G (IgG) from the ANCA-positive serum of patients with ulcerative colitis. However, cotton-top tamarins do not generate serum IgG reactive to cotton-top tamarin or human neutrophils even when equal amounts of IgG are used for antigen detection. As new animal models of spontaneous and induced chronic colitis are developed, the presence of ANCA in serum, using the species' neutrophils, will be useful in relating the immune response of the model to that in human ulcerative colitis.