Complete Thymectomy Research Articles

Postoperative Survival for Patients with Thymoma Complicating Myasthenia Gravis - Preliminary Retrospective Results of the ChART Database

背景与目的重症肌无力（myasthenia gravis, MG）对胸腺瘤患者预后的影响至今尚不明确，本文旨在比较单纯胸腺瘤与合并肌无力胸腺瘤患者的手术预后。方法1992年至2012年中国胸腺协作组（Chinese Alliance for Research in Thymomas, ChART）数据库录入的18个胸外科中心诊断胸腺瘤并接受相关手术的患者分为合并重症肌无力组（合并组）和单纯胸腺瘤组（对照组）。收集两组患者的人口学资料及临床资料，比较两组患者生存率。结果共1, 850例患者纳入研究，其中合并肌无力组及单纯胸腺瘤组分别421人和1429人，行胸腺全切的比例分别是91.2%和71.0%（P < 0.05）；肌无力组患者的WHO病理类型多分布于AB、B1和B2型，优于单纯胸腺瘤组（P < 0.05）；合并肌无力组的Masaoka分期较早（Ⅰ和Ⅱ期）的比例高于单纯胸腺瘤组。5年和10年的总体生存率在MG组和非MG组中分别为93%和88%; 83%和81%（P=0.034）；在Masaoka Ⅲ、Ⅳa和Ⅳb期胸腺瘤患者中，合并肌无力患者的生存曲线高于单纯胸腺瘤患者（P=0.003）。在进展型胸腺瘤患者中，MG组和非MG组患者的Masaoka Ⅲ、Ⅳa、Ⅳb的构成比相似，组织学结果中，MG组的AB/B1/B2/B3型的比例高于C型比例更高的非MG组（P < 0.001）。整体的单因素分析结果提示，MG、WHO分型、Masaoka分期、手术方式、化疗、放疗和临床切除状况均为预后的影响因素。而在多因素分析中，WHO分型、Masaoka分期和临床切除状况是独立的预后预测指标。结论虽然重症肌无力不是独立的预后影响因素，但是在胸腺瘤患者中，合并MG的患者预后较优，尤其是Masaoka分期晚期的患者，可能与疾病的早期发现、病理类型分布相对较好、整体R0切除率较高以及复发率较低有关。

Association of B-cell activating factor receptor deficiency with the P21R polymorphism and common variable immunodeficiency

Association of B-cell activating factor receptor deficiency with the P21R polymorphism and common variable immunodeficiency

Complete thymectomy in adult rats with non-invasive endotracheal intubation.

Thymectomy in neonatal rodents is an established and reliable procedure for immunological studies. However, in adult rats, complications of hemorrhage and pneumothorax from pleural disruption can result in a significant mortality rate. This protocol is a simple method of rat thymectomy that utilizes a mini-sternotomy and endotracheal intubation. Intubation is accomplished with a non-invasive and easily reproducible method and allows for positive pressure ventilation to prevent pneumothorax and a controlled airway that allows sufficient time for careful thymus dissection to minimize pleural disruption. A 1.5 cm sternal incision decreases contact with mediastinal vessels and pleura, while still providing full visualization of the thymus. Following exposure of the mediastinum, the thymus is removed by blunt dissection under magnification. The pleural space is then sealed by suture closure of the pre-tracheal muscles followed by the application of surgical glue. The thorax is then closed by suture closure of the sternum, followed by suture closure of the skin. All thymectomies were complete as evidenced by immunohistochemical (IHC) staining of mediastinal tissue, and absence of naïve T-cells by flow cytometry, and the procedure had a 96% survival rate. This method is suitable when complete thymectomy with minimal complications is desired for further immunological studies in athymic adult rats.

Complete Thymectomy in Adult Rats with Non-invasive Endotracheal Intubation

Complete Thymectomy in Adult Rats with Non-invasive Endotracheal Intubation

Hybrid endoscopic thymectomy: combined transesophageal and transthoracic approach in a survival porcine model with cadaver assessment.

Video-assisted thoracoscopic surgery thymectomy has been used in the treatment of Myastenia Gravis and thymomas (coexisting or not). In natural orifice transluminal endoscopic surgery, new approaches to the thorax are emerging as alternatives to the classic transthoracic endoscopic surgery. The aim of this study was to assess the feasibility and reliability of hybrid endoscopic thymectomy (HET) using a combined transthoracic and transesophageal approach. Twelve consecutive in vivo experiments were undertaken in the porcine model (4 acute and 8 survival). The same procedure was assessed in a human cadaver afterward. For HET, an 11-mm trocar was inserted in the 2nd intercostal space in the left anterior axillary line. A 0° 10-mm thoracoscope with a 5-mm working channel was introduced. Transesophageal access was created through a submucosal tunnel using a flexible gastroscope with a single working channel introduced through the mouth. Using both flexible (gastroscope) and rigid (thoracoscope) instruments, the mediastinum was opened; the thymus was dissected, and the vessels were ligated using electrocautery alone. Submucosal tunnel creation and esophagotomy were performed safely without incidents in all animals. Complete thymectomy was achieved in all experiments. All animals in the survival group lived for 14 days. Thoracoscopic and postmortem examination revealed pleural adhesions on site of the surgical procedure with no signs of infection. Histological analysis of the proximal third of the esophagus revealed complete cicatrization of both mucosal defect and myotomy site. In the human cadaver, we were able to replicate all the procedure even though we were not able to identify the thymus. Hybrid endoscopic thymectomy is feasible and reliable. HET could be regarded as a possible alternative to classic thoracoscopic approach for patients requiring thymectomy.

Thymektomie bei Myasthenie und/oder Thymom

Thymectomy, the surgical removal of the thymic gland, is essential in cases of thymoma. The majority of cases of a myasthenia gravis (MG) represent a relative indication for thymectomy which requires cooperation with specialized neurologists. Patients with MG may present with a tumor of the thymic gland. In case of suspicious thymoma, the resectability of the tumor has to be evaluated in the preoperative diagnostic. The clinical condition of patients with MG has to be stabilized preoperatively. The aim of thymectomy is the radical removal of thymoma and/or maximal improvement of MG symptoms. This requires the complete extirpation of the thymic gland including all ectopic thymic tissue in the anterior mediastinum. There is a variety of surgical techniques for performing a complete thymectomy. In addition to the conventional techniques with sternotomy, the significance of minimally-invasive approaches is increasing rapidly. Despite the ongoing scarcity of data of higher evidence concerning the procedure of thymectomy an increasing number of equivalent results with minimally-invasive operation techniques for MG and for thymoma are available. The successful surgical performance of a thymectomy is part of an interdisciplinary cooperation in the perioperative treatment of MG as well as the postoperative long-term care for patients with MG and/or thymoma.

Standard terms, definitions, and policies for minimally invasive resection of thymoma

Having a common language including well-defined terms and adherence to certain policies and procedures in the management of patients with thymic malignancies is necessary to facilitate progress. This is especially true for minimally invasive resections. Different technical approaches have been used,1,2 and a careful examination of results is needed to understand the impact of the minimally invasive approach itself, as opposed to other factors. For example, during an open approach, most surgeons perform a complete en bloc resection of the tumor and a complete thymectomy with removal of the upper cervical poles and the surrounding mediastinal fat3; whether this is done during minimally invasive resections is hard to decipher at present. This article identifies key aspects that should be reported, common definitions that should be adopted and proposes certain standard policies that should be adhered to when performing a minimally invasive resection of a thymic malignancy. These definitions and policies do not apply to biopsies. These policies are not meant to stifle innovation; on the contrary, they should facilitate progress by providing a framework, so that experiences and outcomes can be compared and analyzed more clearly. These standards have been adopted by members of the International Thymic Malignancy Interest Group (ITMIG), which is a worldwide collaborative organization of individuals interested in mediastinal tumors. METHODS An initial work group of surgeons experienced in minimally invasive thymic resections was assembled to review definitions, terms, and procedures in the existing literature for minimally invasive thymoma resections (Alper Toker, Joshua Sonett, Marcin Zielinski, Federico Rea, Victor Tomulescu, and Frank C. Detterbeck). This work group formulated preliminary recommendations, which were refined by an extended work group (Harmik Soukiasian, Jens Ruckert, Mahmoud Ismail, Jeffrey Port, and Paul Van Schil). These were then debated among a large diverse group of specialists at an ITMIG workshop, which was supported by the International Association for the Study of Lung Cancer. After further comments by the entire ITMIG membership, the definitions and policies presented in this article were approved and adopted as a standard to follow in reporting data and discussing outcomes by the members of ITMIG.

Which way is up? Policies and procedures for surgeons and pathologists regarding resection specimens of thymic malignancy

Thymic malignancies are relatively uncommon, which mandates that the experience from many different institutions be combined to achieve a better understanding of the disease. Nevertheless, this is hampered by many ambiguities in how results are reported and interpreted. This problem is aggravated by the fact that smaller institutions often encounter these tumors only sporadically. A prerequisite to interinstitutional collaboration is a common language and consistency in the definition of findings (e.g., whether a complete resection was accomplished or not). This article summarizes the policies adopted by the International Thymic Malignancy Interest Group (ITMIG) regarding handling of a resection specimen by the surgeon and pathologist and reporting of the surgical and pathologic findings. These policies are based as much as possible on reported evidence, but this is lacking or limited in many areas. Nevertheless, adoption of a consistent approach is crucial to conduct valid studies moving forward that can clarify areas of uncertainty. This publication addresses only how to handle and process the tissue specimen at the time of a resection. It does not address handling and interpretation of biopsies or cytologic specimens, which is an important topic that is addressed in a separate publication.1 This article is limited to an open resection (by sternotomy). Although other approaches are sometimes used (e.g., thoracoscopy), the issues involved are also covered in another publication.2 Furthermore, this article is written with the assumption that resection of a thymoma involves a complete thymectomy along with any adjacent structures that may be involved and that the goal is a complete (R0) resection (i.e., not debulking).

Complete but not partial thymectomy in early infancy reduces T-cell–mediated immune response: Three-year tracing study after pediatric cardiac surgery

Thymectomy is often performed to secure an operative field in surgery for congenital heart defects in early infancy. However, how neonatal thymectomy affects the subsequent development of the immune system in humans remains unclear. We monitored patients for 3 years from the time of thymectomy that was performed during cardiac surgery in early infancy. For up to 3 years, we monitored the number of circulating lymphocytes and the clinical course of the children who underwent complete (n = 17), partial, and no (n = 15) thymectomy during congenital heart defect surgery performed at less than 3 months of age. The titers of immunoglobulin-G produced in response to vaccinated viruses and phytohemagglutinin responses were also measured. Six months after surgery, the number of T cells, including CD4(+) and CD8(+) subpopulations, decreased in patients with complete but not partial thymectomy. The reduction in T-cell number persisted for 3 years, whereas the number of B cells did not change. In patients with complete thymectomy, the titers of immunoglobulin-G produced in response to vaccinated measles and rubella viruses were reduced, whereas the phytohemagglutinin-induced proliferation of T cells was not impaired. In addition, hospitalization frequency associated with infectious diseases increased in patients with complete but not partial thymectomy. The results revealed that complete thymectomy in early infancy reduces the number of circulating T cells and T-cell-mediated immune responses for at least 3 years, suggesting that the thymus should be at least partially preserved during surgery in early infancy to maintain protective immunity.

Video-Assisted Thymectomy with Contralateral Surveillance Camera a Means to Minimize the Risk of Contralateral Phrenic Nerve Injury

Thymectomy for thymoma has traditionally been performed through midsternotomy that provides excellent exposure for a complete and safe resection. Minimally invasive alternatives have not been extensively evaluated for this disease process because data regarding the long-term oncologic effectiveness of these techniques remain to be established. Furthermore, video-assisted surgery as a unilateral approach may compromise the extension of the resection and could cause irreversible damage to the phrenic nerve of the opposite side. We evaluated the clinical feasibility and safety of a bilateral concomitant video-assisted approach with contralateral surveillance camera in patients undergoing thymectomy for thymoma. Four patients (3 females, 1 male) with thymoma causing myasthenia gravis (MG) were operated thoracoscopically at our institute under general anesthesia with double-lumen endotracheal intubation. The patients were placed in a supine position, and a 5-mm 30-degree lens thoracoscope was introduced into the left pleural space. Two other 10-mm working channels were applied. En bloc thymectomy was then performed, including mediastinal and pericardial fat pads, other tissue, and pleura from the level of the thoracic inlet to the diaphragm. A second 5-mm thoracoscope was inserted into the right hemithorax, and it was kept inside during the entire procedure to allow lateral surveillance of the extension and safety of the resection. Carbon dioxide insufflation and valved ports were used. The duration of the operation was 90 ± 72 minutes. Complete resection was achieved in all patients without any nerve injury. There were no perioperative adverse events. Gradual remission from extremity and ocular weakness was achieved after recovery. The ultimate surgical goal of thymectomy is to completely remove the gland and anterior mediastinal tissue without nerve injury. Bilateral concomitant video-assisted thoracic thymectomy with a contralateral surveillance camera was found feasible and safe. Given the capability of our technique to perform a complete and extensive thymectomy associated with less invasiveness and beneficial effects, there seems to be a role for minimally invasive thymectomy in the treatment of thymoma.

Robot-assisted thymectomy is superior to transsternal thymectomy

Complete thymectomy is the procedure of choice in the treatment of thymomas and in treating selected patients with myasthenia gravis. Transsternal thymectomy is the gold standard for most patients. Robot-assisted thymectomy has emerged as an alternative to open transsternal surgery. The goal of this study was to compare perioperative outcomes in patients who underwent transsternal or robot-assisted thymectomy. We performed a retrospective review of all patients who underwent robot-assisted or transsternal thymectomy at our institution from February 2001 to February 2010. Data are presented as mean±SD. Significance was set as P<0.05. Fifty patients underwent either transsternal (n=35) or robot-assisted (n=15) thymectomy. Patient demographics and the incidence of myasthenia gravis were similar between groups. There were no intraoperative complications or conversions to open surgery in the robot-assisted group. Intraoperative blood loss was significantly higher in the transsternal group (151.43 vs. 41.67ml, P=0.01). There were 20 postoperative complications and 1 postoperative death in the transsternal group and 1 postoperative complication in the robot-assisted group (P=0.001). Hospital length of stay was 4days (range 2-27days) in the transsternal group and 1day (range 1-7days) in the robot-assisted group (P=0.002). Robot-assisted thymectomy is superior to transsternal thymectomy, reducing intraoperative blood loss, postoperative complications, and hospital length of stay. Further investigation of the long-term oncologic results in thymoma patients and long-term remission rates in patients with myasthenia gravis who underwent robot-assisted thymectomy is warranted.

Robotic thymectomy: The Hong Kong experience.

Thymectomy is widely employed as part of the management for generalized myasthenia gravis. The surgical approach has evolved over the years, and although there is no consensus regarding the optimal surgical approach, minimally invasive techniques such as video-assisted thoracoscopic thymectomy have gained popularity. Robotic-assisted surgical systems have been employed in recent years to perform thymectomies as the robotic arm allows extra wrist action of the instruments which provide seven degrees of movement, giving improved dexterity compared to the conventional thoracoscopic approach. Here we describe our early experience with the da Vinci system in thymectomy. Between April 2006 and November 2009, 12 robotic-assisted complete thymectomy procedures were performed with no need for conversion to open procedures. Operation times ranged from 100 minutes to 200 minutes (mean time 140 minutes). There were no intraoperative or postoperative complications. Nearly all chest drains were removed on postoperative day 1 and the mean hospital stay was 4 days. The follow-up period ranged from 2 to 44 months. Early postoperative evaluations showed one patient had complete remission of symptoms (DeFilippi class 1) and 11 patients became asymptomatic or less symptomatic with a decreased medication requirement (DeFilippi class 2 and 3). Our early experience suggests that robotic thymectomy is comparable to video-assisted thoracic surgery thymectomy, and our results appear to be comparable to those reported in the literature. A larger number of cases and more extended follow up is needed to fully evaluate the merits of robotic thymectomy.

Association of Thymectomy With Infection Following Congenital Heart Surgery

Congenital absence of the thymus can lead to profound immunodeficiency, suggesting that thymic function during fetal development is essential to normal lymphocyte development. How vital the thymus after birth is to human immune competence and regulation is not known. Routine thymectomy, especially at an early age, may influence immunity, and therefore the risk of infection, autoimmunity, or malignancy. A retrospective review of cardiac surgery patients followed at Seattle Children's Hospital was performed. The primary outcome was rate of serious infections requiring hospitalization. Secondary analyses included age, type of infection, cardiac diagnosis, surgical procedure, and comorbidities. Patients fell into 2 groups: 60 with complete thymectomy and 35 with partial or no thymectomy. There was no statistical difference between groups in the overall prevalence of serious infections (16.7% vs 17.2%, P = 1.0). There was a nonsignificant trend toward reduced time between surgery and onset of first infection in patients in the total thymectomy group versus those without thymectomy (1.7 years vs 4.6 years, P = .07). Total thymectomy before 6 months of age also tended to increase infection rate, but the effect was not significant (0.09/year vs 0.02, P = .14). Gastroesophageal reflux in patients with total thymectomy increased the risk of infection (P = .013), suggesting a cumulative effect. Though infections occurred frequently in the childhood cardiac surgery population, total thymectomy was not associated with increased risk of serious infection. Comorbid conditions may be more important contributing factors increasing the risk of infection in this complex and vulnerable population.

Standard Terms, Definitions, and Policies for Minimally Invasive Resection of Thymoma

Having a common language including well-defined terms and adherence to certain policies and procedures in the management of patients with thymic malignancies is necessary to facilitate progress. This is especially true for minimally invasive resections. Different technical approaches have been used,1,2 and a careful examination of results is needed to understand the impact of the minimally invasive approach itself, as opposed to other factors. For example, during an open approach, most surgeons perform a complete en bloc resection of the tumor and a complete thymectomy with removal of the upper cervical poles and the surrounding mediastinal fat3; whether this is done during minimally invasive resections is hard to decipher at present. This article identifies key aspects that should be reported, common definitions that should be adopted and proposes certain standard policies that should be adhered to when performing a minimally invasive resection of a thymic malignancy. These definitions and policies do not apply to biopsies. These policies are not meant to stifle innovation; on the contrary, they should facilitate progress by providing a framework, so that experiences and outcomes can be compared and analyzed more clearly. These standards have been adopted by members of the International Thymic Malignancy Interest Group (ITMIG), which is a worldwide collaborative organization of individuals interested in mediastinal tumors. METHODS An initial work group of surgeons experienced in minimally invasive thymic resections was assembled to review definitions, terms, and procedures in the existing literature for minimally invasive thymoma resections (Alper Toker, Joshua Sonett, Marcin Zielinski, Federico Rea, Victor Tomulescu, and Frank C. Detterbeck). This work group formulated preliminary recommendations, which were refined by an extended work group (Harmik Soukiasian, Jens Ruckert, Mahmoud Ismail, Jeffrey Port, and Paul Van Schil). These were then debated among a large diverse group of specialists at an ITMIG workshop, which was supported by the International Association for the Study of Lung Cancer. After further comments by the entire ITMIG membership, the definitions and policies presented in this article were approved and adopted as a standard to follow in reporting data and discussing outcomes by the members of ITMIG.

Which Way is Up? Policies and Procedures for Surgeons and Pathologists Regarding Resection Specimens of Thymic Malignancy

Thymic malignancies are relatively uncommon, which mandates that the experience from many different institutions be combined to achieve a better understanding of the disease. Nevertheless, this is hampered by many ambiguities in how results are reported and interpreted. This problem is aggravated by the fact that smaller institutions often encounter these tumors only sporadically. A prerequisite to interinstitutional collaboration is a common language and consistency in the definition of findings (e.g., whether a complete resection was accomplished or not). This article summarizes the policies adopted by the International Thymic Malignancy Interest Group (ITMIG) regarding handling of a resection specimen by the surgeon and pathologist and reporting of the surgical and pathologic findings. These policies are based as much as possible on reported evidence, but this is lacking or limited in many areas. Nevertheless, adoption of a consistent approach is crucial to conduct valid studies moving forward that can clarify areas of uncertainty. This publication addresses only how to handle and process the tissue specimen at the time of a resection. It does not address handling and interpretation of biopsies or cytologic specimens, which is an important topic that is addressed in a separate publication.1 This article is limited to an open resection (by sternotomy). Although other approaches are sometimes used (e.g., thoracoscopy), the issues involved are also covered in another publication.2 Furthermore, this article is written with the assumption that resection of a thymoma involves a complete thymectomy along with any adjacent structures that may be involved and that the goal is a complete (R0) resection (i.e., not debulking).

Combined Unilateral-Thoracoscopic and Mediastinoscopic Thymectomy

To achieve maximal benefit, after thymic tissue and mediastinal fat were removed by thoracoscopic thymectomy, a transverse cervical incision allowed access to remove fat in the neck. A mediastinoscopy was then performed for removal of the fat in the retrosternal area superior to the innominate vein. In 15 cases, ectopic thymic tissue was found. There were three cases in which the residual superior horns of thymus were found in the neck and three in the retrosternal area. The combined use of a mediastinoscope and a thoracoscope can remove almost all the thymus, including ectopic tissues. Long-term results are still being awaited.

Thoracoscopic robot-assisted extended thymectomy in the human cadaver

Thoracoscopic robot-assisted extended thymectomy was performed in a human cadaver. The technique utilized the da Vinci surgical system inserted through the subxiphoid approach with the sternum lifted upward (anteriorly). A small subxiphoid incision and two additional thoracoports were made in the chest wall, and the sternum was lifted by a new lifting retractor system. This method provided sufficient view and working space in the anterior mediastinum. A complete thymectomy was performed with facility. The robotic system provides superior optics and allows for enhanced dexterity. Minimally invasive robotic-assisted thymectomy is an effective procedure and may add benefits for both surgeon and patients.

The construction of improved completely thymectomized adult rats immune model

Objective To establish a stable adult completely thymectomized rat model under the premise of not injuring the removed thymus tissue. Methods Adult SD ♂ rats weighing 150-300 g ( n = 30) were no-invasively intubated under the help of an improved self-made wedge tube set made from a 2 ml plastic syringe and transillumination in front of the rats' neck by an operation spotlight, then the rats were completely thymectomized under ventilation by a small animal breathing machine and × 10 operating microscope. Whether the exsected thymus organ was ntact or not during operation was confirmed, and sur-vival rate of rats was observed, and changes of PBMC T cell reservoir from randomly selected 9 of 30 rats were monitored by FCM within 3 weeks pest-operation. The complete thymectomy rate was confirmed by autopsy and histological examination 3 weeks post-operation. Results The survival rate was 100%, the exsected thymus organ was intact,and the complete thymectomy rate was 100%. Conclusion Completely thymectomized adult rats model can be successfully established in the condition of keeping exsected thymus tissue intact by using a small animal breathing machine under × 10 operating microscope. The removed thymus tissue can be used for transplantation. Key words: Thymectomy; Model,animal; Rat

Human CD4+ T cell recent thymic emigrants are identified by protein tyrosine kinase 7 and have reduced immune function

CD4+ recent thymic emigrants (RTEs) comprise a clinically and immunologically important T cell population that indicates thymic output and that is essential for maintaining a diverse αβ–T cell receptor (TCR) repertoire of the naive CD4+ T cell compartment. However, their frequency and function are poorly understood because no known surface markers distinguish them from older non-RTE naive CD4+ T cells. We demonstrate that protein tyrosine kinase 7 (PTK7) is a novel marker for human CD4+ RTEs. Consistent with their recent thymic origin, human PTK7+ RTEs contained higher levels of signal joint TCR gene excision circles and were more responsive to interleukin (IL)-7 compared with PTK7− naive CD4+ T cells, and rapidly decreased after complete thymectomy. Importantly, CD4+ RTEs proliferated less and produced less IL-2 and interferon-γ than PTK7− naive CD4+ T cells after αβ-TCR/CD3 and CD28 engagement. This immaturity in CD4+ RTE effector function may contribute to the reduced CD4+ T cell immunity observed in contexts in which CD4+ RTEs predominate, such as in the fetus and neonate or after immune reconstitution. The ability to identify viable CD4+ RTEs by PTK7 staining should be useful for monitoring thymic output in both healthy individuals and in patients with genetic or acquired CD4+ T cell immunodeficiencies.

Thoracoscopic robot-assisted extended thymectomy in human cadaver

Thoracoscopic robot-assisted extended thymectomy was performed in a human cadaver. The technique utilized the da Vinci surgical system inserted through the subxiphoid approach with the sternum lifted upward (anteriorly). A small subxiphoid incision and two additional thoracoports were made in the chest wall, and the sternum was lifted by a new lifting retractor system. This method provided sufficient view and working space in the anterior mediastinum. Complete thymectomy was performed with facility. The robotic system provides superior optics and allows for enhanced dexterity. Minimally invasive robotic-assisted thymectomy is an effective procedure and may add benefits for both surgeon and patients.