First ray mobility in hallux rigidus, hallux valgus, and normal feet based on weightbearing computed tomography and three-dimensional analysis: A case-control study.

BACKGROUND: Hallux valgus and hallux rigidus are disorders affecting the first ray and are associated with hypermobility of this structure. This study aimed to investigate the three-dimensional mobility of each joint of the first ray between feet with hallux valgus or hallux rigidus and healthy feet using weightbearing and nonweightbearing computed tomography (CT). METHODS: This case-control study analyzed 17 feet of 11 healthy volunteers (control group), 16 feet of 16 patients with hallux valgus (HV group), and 16 feet of 11 patients with hallux rigidus (HR group). First, nonweightbearing foot CT imaging was performed in the supine position on a loading device with no load applied, with the legs extended and the ankle in the neutral position. Next, a load equivalent to body weight was applied for weightbearing CT imaging. Distal bone displacement relative to the proximal bone was quantified three-dimensionally under both conditions. RESULTS: In the HV group, the talonavicular joint showed significantly greater eversion (P = 00.011) compared with the control group and significantly greater dorsiflexion (P = 00.027) and eversion (P < 00.01) compared with the HR group. In the medial cuneiform joint, the HV group showed significantly greater eversion (P < 00.01) and abduction (P = 00.011) than the control group. For the first tarsometatarsal joint, the HV group showed significantly greater dorsiflexion (P = 00.014), inversion (P = 00.028), and adduction (P < 00.01) than the control group, and greater inversion (P < 00.01) and adduction (P < 00.01) than the HR group. Dorsiflexion of the first tarsometatarsal joint was significantly greater in the HR group compared with the control group (P = 00.026). CONCLUSION: Hypermobility of the first ray appears to be three-dimensional: in hallux valgus, it is centered at the first tarsometatarsal joint, while in hallux rigidus it is mainly in the sagittal plane at the first tarsometatarsal joint only. This difference may explain the different deformities ultimately observed in each condition.

Three-Dimensional Analysis of the Windlass Mechanism Using Weightbearing Computed Tomography in Healthy Volunteers.

BACKGROUND: The windlass mechanism (WM) increases the longitudinal arch of the foot via tension of the plantar aponeurosis during dorsiflexion of the metatarsophalangeal (MTP) joint. The purpose of this study was to perform a 3-dimensional evaluation of the displacement of each joint and the height of the navicular during dorsiflexion of the first MTP joint by using weightbearing computed tomography (CT). METHODS: Participants were 6 men and 8 women with 23 healthy feet. CT of the foot with a load equivalent to the participant's body weight was performed. The first MTP joint was in the neutral position and dorsiflexed 30 degrees. Between the conditions, we measured the (1) rotation of each bone, (2) rotation of the distal bone with respect to the proximal bone at each joint, and (3) height of the navicular. RESULTS: With respect to the tibia, the calcaneus was at 0.8 ± 0.7 degrees dorsiflexion and 1.4 ± 0.9 degrees inversion, while the talus was at 2.0 ± 1.2 degrees dorsiflexion and 0.1 ± 0.8 degrees eversion. The navicular was at 1.3 ± 1.2 degrees dorsiflexion and 3.2 ± 2.1 degrees inversion, whereas the medial cuneiform was at 0.3 ± 0.6 degrees plantarflexion and 1.3 ± 1.1 degrees inversion. At the talonavicular joint, the navicular was at 0.7 ± 1.3 degrees plantarflexion, whereas at the cuneonavicular joint, the medial cuneiform bone was at 1.4 ± 1.4 degrees plantarflexion. The height of the navicular increased by 1.1 ± 0.6 mm. CONCLUSION: We 3-dimensionally confirmed the dynamics of WM and found that the calcaneus, navicular, and medial cuneiform moved in all 3 planes. The results suggest that the cuneonavicular joint has the greatest movement among the joints. We believe that these findings will help to elucidate the pathogenesis of WM-related diseases and lead to advances in treatments for pathologies involving the longitudinal arch. LEVEL OF EVIDENCE: Level IV, case series.

Development of recognised position-guided navigation system.

BACKGROUND: Previously, we developed an image-guided navigation system (IG-NS) incorporating augmented reality technology. Nevertheless, the system could still only aid the operator by presenting imagery and was short of achieving the goal of developing a real navigation system. Therefore, we developed a recognised position-guided navigation system (RP-NS) and herein reported the functionality and usefulness of this system in a phantom model for clinical applications. METHODS: We developed RP-NS which was reconstructed by adding the positional recognition and instruction functions with the cautions by displaying the images on the monitor with a voice to the IG-NS. We evaluated accuracy of positional recognition and instruction functions using phantom model. By utilising the chronological recording of the tip position of the surgical apparatus, the surgical precision of the operators was assessed. Finally, the feasibility of improvements in surgical precision using this system was evaluated. RESULTS: The RP-NS indicated an accuracy of the position recognition functions with an error of 2.7 mm. The surgeons could perform partial hepatectomies within mean value of 7.5% error as compared with calculated volume according to the instruction. Improvements in surgical precision using this system were obtained on the surgeons with different levels. CONCLUSIONS: The RP-NS was highly effective as a navigation system owing to precise positional recognition and adequate instruction functions. Therefore, these results indicate that the use of this system may complement differences in proficiency, and numerically evaluate surgical skills and analyse tendencies of surgeons.

Weightbearing Computed Tomography and 3-Dimensional Analysis of Mobility Changes of the First Ray After Proximal Oblique Osteotomy for Hallux Valgus.

BACKGROUND: Hypermobility of the first ray has been evaluated using various methods and has conventionally been considered to be involved in the pathology of hallux valgus. We hypothesized that hypermobility of the first ray in hallux valgus could be decreased by simply correcting foot alignment without arthrodesis. This study sought to evaluate first-ray mobility using weightbearing computed tomography (CT) before and after proximal oblique osteotomy and also in healthy volunteer's feet. METHODS: Subjects were 11 feet of 11 patients with primary hallux valgus who underwent surgery with a plantarly applied anatomic precontoured locking plate and 22 feet of 11 matched healthy volunteers. We performed nonweightbearing and weightbearing (using a load equivalent to body weight) CT scans using an original loading device preoperatively and 1-1.5 years postoperatively. Three-dimensional displacement of the distal bone relative to the proximal bone was quantified for each joint of the first ray by comparing nonweightbearing and weightbearing CT images. RESULTS: At baseline, there were significant differences in hallux valgus angle (P < .001) and 1-2 intermetatarsal angle (P < .001) between healthy volunteer's feet and preoperative hallux valgus feet. Hallux valgus angle (P < .001) and 1-2 intermetatarsal angle (P < .001) differed significantly between before and after surgery. All first ray joint displacement under loading decreased postoperatively to within 2° of that in healthy volunteer's feet and showed no significant difference between postoperatively hallux valgus feet and healthy volunteer's feet (P > .05). CONCLUSIONS: We found that first metatarsal osteotomy even without arthrodesis corrected deformity and decreased mobility of the first ray after hallux valgus surgery. LEVEL OF EVIDENCE: Level III, case-control study.

Application of image-guided navigation system for laparoscopic hepatobiliary surgery.

BACKGROUND: To achieve safety of the operation, preoperative simulation became a routine practice for hepatobiliary and pancreatic (HBP) surgery. The use of intraoperative ultrasonography (IOUS) is essential in HBP surgery. There is a limitation in the use of IOUS in laparoscopic surgery (LS), for which a new intraoperative system is expected. We have developed an image-guided navigation system (IG-NS) for open HBP surgery since 2006, and we have applied our system to LS. The aim of this study is to evaluate the results of clinical application of IG-NS in LS. MATERIALS AND METHODS: Eight patients underwent LS using IG-NS; LS consisted of cholecystectomy and hepatectomy in four patients each. After registration, the 3D models were superimposed on the surgical field. We performed LS while observing the navigation image. Moreover, we developed a support system for operations. RESULTS: The average registration error was 8.8 mm for LS. Repeated registration was effective for organ deformation and improved the precision of IG-NS. By using various countermeasures, identification of the tumor's position and the setting of the resection line became easy. CONCLUSION: As IG-NS provided real-time detailed and intuitive information, this intraoperative assist system may be an effective tool in LS.

Novel navigation system by augmented reality technology using a tablet PC for hepatobiliary and pancreatic surgery.

BACKGROUND: We previously developed an image-guided navigation system (IG-NS) using augmented reality technology for hepatobiliary and pancreatic (HBP) surgery. This system superimposed a 3D model onto a stereoscope-captured surgical field (i.e., the scope method). Unfortunately, this method requires an expensive stereoscope, surgeons have to shift their eyesight away from the surgical field, and the method has poor controllability. Therefore, an IG-NS using a tablet PC (i.e., the tablet method) was developed. The aim of the current study is to evaluate the efficiency of this novel method. METHODS: We studied 9 patients, for whom a 3D model was created from computed tomography images. After registration was performed, the 3D model was superimposed onto the surgical field, which was captured by the tablet PC's camera. RESULTS: The IG-NS could be applied with very little time lag. The visibility and controllability of the tablet method were superior to those of the scope method. It was especially useful in surgery for multiple metastatic liver carcinoma due to easy localization of the position of the carcinomas and vessels. CONCLUSIONS: We successfully developed the tablet method and tested it in a clinical setting. This system may contribute to surgical efficacy and improve the educational effects.

Comparison of Intercuneiform 1-2 Joint Mobility Between Hallux Valgus and Normal Feet Using Weightbearing Computed Tomography and 3-Dimensional Analysis.

BACKGROUND: An association has been reported between hallux valgus and hypermobility of the first ray, but subluxation of the intercuneiform 1-2 joint was also suspected in some cases. However, dynamics of the intercuneiform 1-2 joint has seldom been investigated. This study used weightbearing computed tomography (CT) and a 3-dimensional (3D) analysis system to evaluate displacement of the intercuneiform 1-2 joint, intercuneiform 2-3 joint, and second cuneonavicular joint due to weightbearing in hallux valgus and normal feet. METHODS: Patients were 11 women with hallux valgus (mean age, 56 years; mean hallux valgus angle, 43 degrees; mean first-second intermetatarsal angle, 22 degrees) and 11 women with normal feet (mean age, 57 years; mean hallux valgus angle, 14 degrees; mean first-second intermetatarsal angle, 9 degrees). Each patient was placed supine with the lower limbs extended, and CT was performed under nonweightbearing and weightbearing conditions (load equivalent to body weight). 3D models reconstructed from CT images were used to compare displacement of the intermediate cuneiform relative to the medial cuneiform under nonweightbearing and weightbearing conditions. RESULTS: Relative to the medial cuneiform, the middle cuneiform was displaced by 0.1 and 0.8 degrees due to dorsiflexion, 0.2 and 1.0 degrees due to inversion, and 0.7 and 0.7 degrees due to abduction in normal feet and feet with hallux valgus, respectively, with the latter having significantly greater dorsiflexion ( P = .0067) and inversion ( P = .0019). There was no significant intergroup difference at the intercuneiform 2-3 joint and second cuneonavicular joint. CONCLUSION: This study clarified the detailed load-induced displacement of the cuneiform 3-dimensionally. Compared with normal feet, hallux valgus feet had significantly greater mobility of the intercuneiform 1-2 joint, suggesting hypermobility of this joint. LEVEL OF EVIDENCE: Level III, case-control study.

Evaluation of First-Ray Mobility in Patients with Hallux Valgus Using Weight-Bearing CT and a 3-D Analysis System: A Comparison with Normal Feet.

BACKGROUND: Some physicians report that patients with hallux valgus have hypermobility at the tarsometatarsal (TMT) joint of the first ray and 3-dimensional (3-D) deformity. With use of non-weight-bearing and weight-bearing computed tomography (CT), we evaluated the 3-D mobility of each joint of the first ray in feet with hallux valgus compared with normal feet. METHODS: Ten feet of 10 patients with hallux valgus and 10 feet of 10 healthy volunteers with no foot disorders were examined. All participants were women. Weight-bearing (a load equivalent to body weight) and non-weight-bearing CT scans were made with use of a device that we developed. Orthogonal coordinate axes were set and a 3-D model was reconstructed. Each joint of the first ray was aligned with the respective proximal bone, and 3-D displacement of the distal bone relative to the proximal bone under loading was quantified. RESULTS: At the talonavicular joint, significantly greater dorsiflexion of the navicular relative to the talus was observed in the hallux valgus group compared with the control group. At the medial cuneonavicular joint, the hallux valgus group showed significantly greater eversion and abduction of the medial cuneiform relative to the navicular. At the first TMT joint, the hallux valgus group showed significantly greater dorsiflexion, inversion, and adduction of the first metatarsal relative to the medial cuneiform. At the first metatarsophalangeal joint, the hallux valgus group showed significantly greater eversion and abduction of the first proximal phalanx relative to the first metatarsal (all p < 0.05). CONCLUSIONS: The results of this study suggest that loading of the foot causes significant 3-D displacement not only at the TMT joint but also at the other joints of the first ray. There is increased mobility in the first ray in patients who have hallux valgus.

Development of Four Dimensional Human Model that Enables Deformation of Skin, Organs and Blood Vessel System During Body Movement - Visualizing Movements of the Musculoskeletal System.

We constructed a four dimensional human model that is able to visualize the structure of a whole human body, including the inner structures, in real-time to allow us to analyze human dynamic changes in the temporal, spatial and quantitative domains. To verify whether our model was generating changes according to real human body dynamics, we measured a participant's skin expansion and compared it to that of the model conducted under the same body movement. We also made a contribution to the field of orthopedics, as we were able to devise a display method that enables the observer to more easily observe the changes made in the complex skeletal muscle system during body movements, which in the past were difficult to visualize.

Navigation surgery using an augmented reality for pancreatectomy.

AIM: The aim of this study was to evaluate the utility of navigation surgery using augmented reality technology (AR-based NS) for pancreatectomy. METHODS: The 3D reconstructed images from CT were created by segmentation. The initial registration was performed by using the optical location sensor. The reconstructed images were superimposed onto the real organs in the monitor display. Of the 19 patients who had undergone hepatobiliary and pancreatic surgery using AR-based NS, the accuracy, visualization ability, and utility of our system were assessed in five cases with pancreatectomy. RESULTS: The position of each organ in the surface-rendering image corresponded almost to that of the actual organ. Reference to the display image allowed for safe dissection while preserving the adjacent vessels or organs. The locations of the lesions and resection line on the targeted organ were overlaid on the operating field. The initial mean registration error was improved to approximately 5 mm by our refinements. However, several problems such as registration accuracy, portability and cost still remain. CONCLUSION: AR-based NS contributed to accurate and effective surgical resection in pancreatectomy. The pancreas appears to be a suitable organ for further investigations. This technology is promising to improve surgical quality, training, and education.

Clinical application of navigation surgery using augmented reality in the abdominal field.

This article presents general principles and recent advancements in the clinical application of augmented reality-based navigation surgery (AR based NS) for abdominal procedures and includes a description of our clinical trial and subsequent outcomes. Moreover, current problems and future aspects are discussed. The development of AR-based NS in the abdomen is delayed compared with another field because of the problem of intraoperative organ deformations or the existence of established modalities. Although there are a few reports on the clinical use of AR-based NS for digestive surgery, sophisticated technologies in urology have often been reported. However, the rapid widespread use of video- or robot assisted surgeries requires this technology. We have worked to develop a system of AR-based NS for hepatobiliary and pancreatic surgery. Then we developed a short rigid scope that enables surgeons to obtain 3D view. We recently focused on pancreatic surgery, because intraoperative organ shifting is minimal. The position of each organ in overlaid image almost corresponded with that of the actual organ with about 5 mm of mean registration errors. Intraoperative information generated from this system provided us with useful navigation. However, AR-based NS has several problems to overcome such as organ deformity, evaluation of utility, portability or cost.

Hip range of motion during daily activities in patients with posterior pelvic tilt from supine to standing position.

In most patients with hip disorders, the anterior pelvic plane (APP) sagittal tilt does not change from supine to standing position. However, in some patients, APP sagittal tilt changes more than 10° posteriorly from supine to standing position. The purpose of this study was to both examine APP sagittal tilt and investigate the hip flexion and extension range of motion (ROM) required during daily activities in these atypical patients. Patient-specific 4-dimensional (4D) motion analysis was performed for 50 hips from 44 patients who had undergone total hip arthroplasty. All patients divided into two categories, such as atypical patients for whom the pelvis tilted more than 10° posteriorly from supine to standing position preoperatively (19 hips from 18 patients) and the remaining typical patients (31 hips from 26 patients). The required hip flexion and extension angles did not differ significantly between atypical patients and typical patients. In conclusion, the hip flexion ROM during deep bending activities and hip extension ROM during extension activities required in those atypical patients with pelvic tilt more than 10° backward from supine to standing position did not shift in the direction of extension.

Development of AR Surgical Navigation Systems for Multiple Surgical Regions.

The purpose of our research is to develop surgical navigation systems to enhance surgical safety. Our systems make use of augmented reality technology to superimpose, on the surgery screen on a real time basis, patients' organ models reconstructed in 3D from their X-ray CT data taken before surgery. By doing so, the systems display anatomical risk materials, tumors and blood vessels which surgeons cannot see with their naked eyes. This will in turn lead to surgeons intuitively grasping the inner structures of the operational fields. We so far have been developing navigation systems that can conduct surgeries in various fields. The basic structure of the navigation systems are the same. The navigation systems uses different peripheral equipment and different methods to display navigation images which best meet the demands of each type of surgery. In this thesis, we report on our navigation systems for 2 types of surgery - endoscopic sinus surgery and hepatobilialy-pancreatic surgery.

A concept for overlaid-type surgical navigation system with organ modification functions using non-contact type surface measurement.

Surgical navigation systems are clinically applied in cerebral and otological surgeries but they are only used in parts with minimum surgical transformation in regions in which the organs largely transform, such as in the abdomen. Therefore, we here propose a concept of a surgical navigation system that could be used in the regions such as liver, which largely transforms itself during surgery. We consider a method that measures the changes in the organ surface configuration during surgery and estimates the changes in the tumor and blood vessel structure following the transformation of the organ surface. We also report on the necessary disposition of each process of this method, especially on the basic examination of the organ transformation.

Identification of inferior pancreaticoduodenal artery during pancreaticoduodenectomy using augmented reality-based navigation system.

BACKGROUND: In pancreaticoduodenectomy (PD), early ligation of the inferior pancreaticoduodenal artery (IPDA) before efferent veins has been advocated to decrease blood loss by congestion of the pancreatic head to be resected. In this study, we herein report the utility of early identification of the IPDA using an augmented reality (AR)-based navigation system (NS). METHODS: Seven nonconsecutive patients underwent PD using AR-based NS. After paired-point matching registration, the reconstructed image obtained by preoperative computed tomography (CT) was fused with a real-time operative field image and displayed on 3D monitors. The vascular reconstructed images, including the superior mesenteric artery, jejunal artery, and IPDA were visualized to facilitate image-guided surgical procedures. We compared operating time and intraoperative blood loss of six patients who successfully underwent identification of IPDA using AR-based NS (group A) with nine patients who underwent early ligation of IPDA without using AR (group B) and 18 patients who underwent a conventional PD (group C). RESULTS: The IPDA or the jejunal artery was rapidly identified and ligated in six patients. The mean operating time and intraoperative blood loss in group A was 415 min and 901 ml, respectively. There was no significant difference in operating time and intraoperative blood loss among the groups. CONCLUSIONS: The AR-based NS provided precise anatomical information, which allowed the surgeons to rapidly identify and perform early ligation of IPDA in PD.

Formulation of wire control mechanism for surgical robot to create virtual reality environment aimed at conducting surgery inside the body.

We here report on the process of developing a surgical robot that can conduct operation "going inside the body without spreading the operational region". The endoscopic robot that we are developing now has a flexible cylindrical body with functions of a set of human arms at the tip and also with vision and haptic sense functions. We evaluated necessary technology factor to complete this robot into categories such as, transmission of energy, adaptation to insides of the body.

Short rigid scope and stereo-scope designed specifically for open abdominal navigation surgery: clinical application for hepatobiliary and pancreatic surgery.

BACKGROUND: We have reported the utility of an image display system using augmented reality (AR) technology in hepatobiliary surgery under laparotomy. Among several procedures, we herein report a system using a novel short rigid scope and stereo-scope, both designed specifically for open abdominal navigation surgery, and their clinical application for hepatobiliary and pancreatic surgery. METHODS: The 3D reconstructed images were obtained from preoperative computed tomography data. In our specialized operating room, after paired-point matching registration, the reconstructed images are overlaid onto the operative field images captured by the short rigid scopes. The scopes, which are compact and sterilizable, can be used in the operative field. The stereo-scope provides depth information. Eight patients underwent operations using this system, including hepatectomy in two, distal pancreatectomy in three, and pancreaticoduodenectomy in three patients. The stereo-scope was used in five patients. RESULTS: All eight operations were performed safely using the novel short rigid scopes, and stereo images were acquired in all five patients for whom the stereo-scope was used. The scopes were user friendly, and the intraoperative time requirement for our system was reduced compared with the conventional method. CONCLUSIONS: The novel short rigid scope and stereo-scope seem to be suitable for clinical use in open abdominal navigation surgery. In hepatobiliary and pancreatic surgery, our novel system may improve the safety, accuracy and efficiency of operations.

Utility of augmented reality system in hepatobiliary surgery.

BACKGROUND/PURPOSE: The aim of this study was to evaluate the utility of an image display system for augmented reality in hepatobiliary surgery under laparotomy. METHODS: An overlay display of organs, vessels, or tumor was obtained using a video see-through system as a display system developed at our institute. Registration between visceral organs and the surface-rendering image reconstructed by preoperative computed tomography (CT) was carried out with an optical location sensor. Using this system, we performed laparotomy for a patient with benign biliary stricture, a patient with gallbladder carcinoma, and a patient with hepatocellular carcinoma. RESULTS: The operative procedures performed consisted of choledochojejunostomy, right hepatectomy, and microwave coagulation therapy. All the operations were carried out safely using images of the site of tumor, preserved organs, and resection aspect overlaid onto the operation field images observed on the monitors. The position of each organ in the overlaid image closely corresponded with that of the actual organ. Intraoperative information generated from this system provided us with useful navigation. However, several problems such as registration error and lack of depth knowledge were noted. CONCLUSION: The image display system appeared to be useful in performing hepatobiliary surgery under laparotomy. Further improvement of the system with individualized function for each operation will be essential, with feedback from clinical trials in the future.

Informatics in radiology: Intuitive user interface for 3D image manipulation using augmented reality and a smartphone as a remote control.

Although widely used as a pointing device on personal computers (PCs), the mouse was originally designed for control of two-dimensional (2D) cursor movement and is not suited to complex three-dimensional (3D) image manipulation. Augmented reality (AR) is a field of computer science that involves combining the physical world and an interactive 3D virtual world; it represents a new 3D user interface (UI) paradigm. A system for 3D and four-dimensional (4D) image manipulation has been developed that uses optical tracking AR integrated with a smartphone remote control. The smartphone is placed in a hard case (jacket) with a 2D printed fiducial marker for AR on the back. It is connected to a conventional PC with an embedded Web camera by means of WiFi. The touch screen UI of the smartphone is then used as a remote control for 3D and 4D image manipulation. Using this system, the radiologist can easily manipulate 3D and 4D images from computed tomography and magnetic resonance imaging in an AR environment with high-quality image resolution. Pilot assessment of this system suggests that radiologists will be able to manipulate 3D and 4D images in the reading room in the near future. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.324115086/-/DC1.

Training system for NOTES and SPS surgery robot that enables spatiotemporal retrospective analysis of the training process.

Within the digestive organ surgery robot R&D project, our research team aims to develop a surgical robot training device with an interface identical to that of the actual device. The training device uses an organ model that changes shape in real time to train operators to grab, cut open, and cut off soft tissues and close wounds using the actual device. To increase the effectiveness of the training device, we added functions to save the movements of the robot in training and changes in the operation field. By recreating the situation during training, we were able to analyze in four dimensions (4D) various changes in the operation field that the operator cannot see during training. This new function not only enabled us to analyze the contents of the training in detail, but also to report any problems in development and design of the actual device.