Landmark-based augmented reality system for paranasal and transnasal endoscopic surgeries

BACKGROUND: In this paper we present a landmark-based augmented reality (AR) endoscope system for endoscopic paranasal and transnasal surgeries along with fast and automatic calibration and registration procedures for the endoscope. METHODS: Preoperatively the surgeon selects natural landmarks or can define new landmarks in CT volume. These landmarks are overlaid, after proper registration of preoperative CT to the patient, on the endoscopic video stream. The specified name of the landmark, along with selected colour and its distance from the endoscope tip, is also augmented. The endoscope optics are calibrated and registered by fast and automatic methods. Accuracy of the system is evaluated in a metallic grid and cadaver set-up. RESULTS: Root mean square (RMS) error of the system is 0.8 mm in a controlled laboratory set-up (metallic grid) and was 2.25 mm during cadaver studies. CONCLUSIONS: A novel landmark-based AR endoscope system is implemented and its accuracy is evaluated. Augmented landmarks will help the surgeon to orientate and navigate the surgical field. Studies prove the capability of the system for the proposed application. Further clinical studies are planned in near future.

Evaluation of Medical Students’ Attitudes and Performance of Basic Surgery Skills in a Training Program Using Fresh Human skin, Excised During Body Contouring Surgeries

BACKGROUND: Learning surgical skills in the operating room may be a challenge for medical students. Therefore, more approaches using simulation to enable students to develop their practical skills are required. OBJECTIVES: We hypothesized that (1) there would be a need for additional surgical training for medical students in the pre-final year, and (2) our basic surgery skills training program using fresh human skin would improve medical students' surgical skills. DESIGN: We conducted a preliminary survey of medical students to clarify the need for further training in basic surgery procedures. A new approach using simulation to teach surgical skills on human skin was set up. The procedural skills of 15 randomly selected students were assessed in the operating room before and after participation in the simulation, using Objective Structured Assessment of Technical Skills. Furthermore, subjective assessment was performed based on students' self-evaluation. The data were analyzed using SPSS, version 21 (SPSS, Inc., Chicago, IL). SETTING: The study took place at the Inselspital, Bern University Hospital. PARTICIPANTS: A total of 186 pre-final-year medical students were enrolled into the preliminary survey; 15 randomly selected medical students participated in the basic surgical skills training course on the fresh human skin operating room. RESULTS: The preliminary survey revealed the need for a surgical skills curriculum. The simulation approach we developed showed significant (p < 0.001) improvement for all 12 surgical skills, with mean cumulative precourse and postcourse values of 31.25 ± 5.013 and 45.38 ± 3.557, respectively. The self-evaluation contained positive feedback as well. CONCLUSION: Simulation of surgery using human tissue samples could help medical students become more proficient in handling surgical instruments before stepping into a real surgical situation. We suggest further studies evaluating our proposed teaching method and the possibility of integrating this simulation approach into the medical school curriculum.

Comparison of actual surgical outcomes and 3-dimensional surgical simulations

PURPOSE: The advent of imaging software programs has proved to be useful for diagnosis, treatment planning, and outcome measurement, but precision of 3-dimensional (3D) surgical simulation still needs to be tested. This study was conducted to determine whether the virtual surgery performed on 3D models constructed from cone-beam computed tomography (CBCT) can correctly simulate the actual surgical outcome and to validate the ability of this emerging technology to recreate the orthognathic surgery hard tissue movements in 3 translational and 3 rotational planes of space. MATERIALS AND METHODS: Construction of pre- and postsurgery 3D models from CBCTs of 14 patients who had combined maxillary advancement and mandibular setback surgery and 6 patients who had 1-piece maxillary advancement surgery was performed. The postsurgery and virtually simulated surgery 3D models were registered at the cranial base to quantify differences between simulated and actual surgery models. Hotelling t tests were used to assess the differences between simulated and actual surgical outcomes. RESULTS: For all anatomic regions of interest, there was no statistically significant difference between the simulated and the actual surgical models. The right lateral ramus was the only region that showed a statistically significant, but small difference when comparing 2- and 1-jaw surgeries. CONCLUSIONS: Virtual surgical methods were reliably reproduced. Oral surgery residents could benefit from virtual surgical training. Computer simulation has the potential to increase predictability in the operating room.

Treatment of the symptomatic healed Perthes hip

Healed Legg-Calvé-Perthes disease may cause both intra-articular and extra-articular impingement, resulting in a symptomatic hip prior to the onset of osteoarthritis. Various impingement-relieving surgeries have been used in the past; however, the development of the safe surgical dislocation technique has allowed a better understanding of complex deformity that may be present in these hips and hence may improve treatment of these symptomatic prearthritic hips. This article outlines the range of deformities possible in a Perthes hip, and treatment strategies to surgically address these deformities. For Perthes disease good preoperative clinical and radiographic assessment is essential, and intraoperative assessment vital.

Enamel matrix protein adsorption to root surfaces in the presence or absence of human blood

Background: The clinical use of an enamel matrix derivative (EMD) has been shown to promote formation of new cementum, periodontal ligament (PDL), and bone and to significantly enhance the clinical outcomes after regenerative periodontal surgery. It is currently unknown to what extent the bleeding during periodontal surgery may compete with EMD adsorption to root surfaces. The aim of this study is to evaluate the effect of blood interactions on EMD adsorption to root surfaces mimicking various clinical settings and to test their ability to influence human PDL cell attachment and proliferation. Methods: Teeth extracted for orthodontic reasons were subjected to ex vivo scaling and root planing and treated with 24% EDTA, EMD, and/or human blood in six clinically related settings to determine the ability of EMD to adsorb to root surfaces. Surfaces were analyzed for protein adsorption via scanning electron microscopy and immunohistochemical staining with an anti-EMD antibody. Primary human PDL cells were seeded on root surfaces and quantified for cell attachment and cell proliferation. Results: Plasma proteins from blood samples altered the ability of EMD to adsorb to root surfaces on human teeth. Samples coated with EMD lacking blood demonstrated a consistent even layer of EMD adsorption to the root surface. In vitro experiments with PDL cells demonstrated improved cell attachment and proliferation in all samples coated with EMD (irrespective of EDTA) when compared to samples containing human blood. Conclusion: Based on these findings, it is advised to minimize blood interactions during periodontal surgeries to allow better adsorption of EMD to root surfaces.

Long-Term Outcome After Monosegmental L4/5 Stabilization for Degenerative Spondylolisthesis With the Dynesys Device

STUDY DESIGN:: retrospective analysis of prospectively collected clinical data. OBJECTIVE:: To assess the long-term outcome of patients with monosegmental L4/5 degenerative spondylolisthesis treated with the dynamic Dynesys device. SUMMARY OF BACKGROUND DATA:: The Dynesys® system has been used as a semirigid, lumbar dorsal pedicular stabilization device since 1994. Good short-term results have been reported, but little is known about the long-term outcome following treatment for degenerative spondylolisthesis at the L4/5 level. METHODS:: 39 consecutive patients with symptomatic degenerative lumbar spondylolisthesis at the L4/5 level were treated with bilateral decompression and Dynesys instrumentation. At a mean follow-up of 7.2 years (range 5.0-11.2▒y) they underwent clinical and radiographic evaluation and quality of life assessment. RESULTS:: At final follow-up back pain improved in 89% and leg pain improved in 86% of patients compared to preoperative status. 83% of patients reported global subjective improvement. 92% would undergo the surgery again. 8 patients (21%) required further surgery due to symptomatic adjacent segment disease (6 cases), late onset infection (1 case), and screw breakage (1 case). In 9 cases radiological progression of spondylolisthesis at the operated segment was found. 74% of operated segments showed limited flexion-extension range of less than 4°. Adjacent segment pathology, though without clinical correlation, was diagnosed at the L5/S1 (17.9%) and L3/4 (28.2%) segments. In 4 cases asymptomatic screw loosening was observed. CONCLUSION:: Monosegmental Dynesys instrumentation of degenerative spondylolisthesis at L4/5 shows good long-term results. The rate of secondary surgeries is comparable to other dorsal instrumentation devices. Residual range of motion in the stabilized segment is reduced, and the rate of radiological and symptomatic adjacent segment degeneration is low. Patient satisfaction is high. Dynesys stabilization of symptomatic L4/5 degenerative spondylolisthesis is a possible alternative to other stabilization devices.

Should aortic arch replacement be performed during initial surgery for aortic root aneurysm in patients with Marfan syndrome?

OBJECTIVES: The aim of this study was to investigate whether total arch replacement (TAR) during initial surgery for root aneurysm should be routinely performed in patients with Marfan syndrome (MFS). METHODS: Retrospective analysis of 94 consecutive MFS patients fulfilling Ghent criteria who underwent 148 aortic surgeries and were followed at this institution during the past 16 years. RESULTS: The mean follow-up interval was 8.8 ± 7 years. Initial presentation was acute aortic dissection (AAD) in 35% of patients (76% Type A and 24% Type B) and aneurismal disease in 65%. TAR was performed in 8% of patients during initial surgery for AAD (otherwise a hemi-arch replacement was performed) and 1.6% in elective root repair. Secondary TAR had to be performed in only 3% of patients without, but in 33% following AAD (33% Type A and 33% Type B; P = 0.0001). Thirty-day, 6-month, 1-year and overall mortalities were 3.2, 5.3, 6.4 and 11.7%, respectively. Operative and 30-day mortalities in secondary aortic arch replacement were zero. Secondary TAR after AAD did not increase the need for the replacement of the entire thoracoabdominal aorta during follow-up compared with patients without secondary TAR (37 vs 40%, P = 1.0). CONCLUSIONS: MFS patients undergoing elective root repair have small risk of reinterventions on the aortic arch, and primary prophylactic replacement does not seem to be justified. In patients with AAD, the need for reinterventions is precipitated by the dissection itself and not by limiting the procedure to the hemi-arch replacement in the emergency setting. Limiting surgery to the aortic root, ascending aorta and proximal aortic arch is associated with low mortality in MFS patients presenting with AAD.

Expanded polytetrafluoroethylene graft for bypass surgery using the excimer laser-assisted nonocclusive anastomosis technique

OBJECT: Patients with complex craniocerebral pathophysiologies such as giant cerebral aneurysms, skull base tumors, and/or carotid artery occlusive disease are candidates for a revascularization procedure to augment or preserve cerebral blood flow. However, the brain is susceptible to ischemia, and therefore the excimer laser-assisted nonocclusive anastomosis (ELANA) technique has been developed to overcome temporary occlusion. Harvesting autologous vessels of reasonable quality, which is necessary for this technique, may at times be problematic or impossible due to the underlying systemic vascular disease. The use of artificial vessels is therefore an alternative graft for revascularization. Note, however, that it is unknown to what degree these grafts are subject to occlusion using the ELANA anastomosis technique. Therefore, the authors studied the ELANA technique in combination with an expanded polytetrafluoroethylene (ePTFE) graft. METHODS: The experimental surgeries involved bypassing the abdominal aorta in the rabbit. Ten rabbits were subjected to operations representing 20 ePTFE graft-ELANA end-to-side anastomoses. Intraoperative blood flow, followup angiograms, and long-term histological characteristics were assessed 75, 125, and 180 days postoperatively. Angiography results proved long-term patency of ePTFE grafts in all animals at all time points studied. Data from the histological analysis showed minimal intimal reaction at the anastomosis site up to 180 days postoperatively. Endothelialization of the ePTFE graft was progressive over time. CONCLUSIONS: The ELANA technique in combination with the ePTFE graft seems to have favorable attributes for end-to-side anastomoses and may be suitable for bypass procedures.