Navigation Surgery Research Articles

An incremental registration method for endoscopic sinus and skull base surgery navigation: From phantom study to clinical trials.

Surface-based image-to-patient registration in current surgical navigation is mainly achieved by a 3D scanner, which has several limitations in clinical practice such as uncontrollable scanning range, complicated operation, and even high failure rate. An accurate, robust, and easy-to-perform image-to-patient registration method is urgently required. An incremental point cloud registration method was proposed for surface-based image-to-patient registration. The point cloud in image space was extracted from the computed tomography (CT) image, and a template matching method was applied to remove the redundant points. The corresponding point cloud in patient space was incrementally collected by an optically tracked pointer, while the nearest point distance (NPD) constraint was applied to ensure the uniformity of the collected points. A coarse-to-fine registration method under the constraints of coverage ratio (CR) and outliers ratio (OR) was then proposed to obtain the optimal rigid transformation from image to patient space. The proposed method was integrated in the recently developed endoscopic navigation system, and phantom study and clinical trials were conducted to evaluate the performance of the proposedmethod. The results of the phantom study revealed that the proposed constraints greatly improved the accuracy and robustness of registration. The comparative experimental results revealed that the proposed registration method significantly outperform the scanner-based method, and achieved comparable accuracy to the fiducial-based method. In the clinical trials, the average registration duration was 1.24 ± 0.43 min, the target registration error (TRE) of 294 marker points (59 patients) was 1.25 ± 0.40 mm, and the lower 97.5% confidence limit of the success rate of positioning marker points exceeds the expected value (97.56% vs. 95.00%), revealed that the accuracy of the proposed method significantly met the clinical requirements (TRE ⩽ 2 mm, p<0.05). The proposed method has both the advantages of high accuracy and convenience, which were absent in the scanner-based method and the fiducial-based method. Our findings will help improve the quality of endoscopic sinus and skull basesurgery.

Small steps to thousands of miles: a tribute to Chinese laparoscopic gastric cancer surgery

Laparoscopic surgery for gastric cancer has been developed in China for more than 20 years. It has gone through the initial stage of exploration in the 1990s, the stage of learning and accumulation in the early 21st century, the stage of development and expansion in the 2010s, and the current stage of standardization, and innovation. Laparoscopic gastric cancer surgery in China has developed from less to more, from more to popular. Surgical techniques have gradually become mature, innovated, and standardized, medical evidence has accumulated, and academic exchanges have become increasingly active and valued by the world. In the future, it is expected to make new progress and breakthrough in tumor specific laparoscopic navigation surgery system, intelligent robotic gastric cancer surgery platform, functional preservation surgery for early gastric cancer under the integration of gastroenterologists and surgeons, and laparoscopic comprehensive treatment for peritoneal metastasis. By reviewing the development of laparoscopic gastric cancer surgery in China, the authors draw inspiration from the depths of history, inherit and innovate, look forward to the future, and pay tribute to the predecessors.

Tumor microenvironment enhanced NIR II fluorescence imaging for tumor precise surgery navigation via tetrasulfide mesoporous silica-coated Nd-based rare-earth nanocrystals.

In vivo fluorescent imaging by using the new contrast agents emitted at short-wavelength infrared region (NIR II, 1000–1700 ​nm) presents an unprecedent advantages in imaging sensitivity and spatial resolution over traditional near-infrared (NIR) light. Recently, Nd-based rare-earth nanocrystals have attracted considerable attention due to the high quantum yield (∼40%) of their emission at NIR II. However, undesirable capture by reticuloendothelial system to bring strong background signal is unsatisfying for tumor discrimination. Here, GSH-sensitive tetrasulfide bond incorporated mesoporous silica shell has entrusted onto Nd-based down-conversion nanocrystals (DCNPs) surface to totally quench the fluorescence of DCNPs. After RGD conjugation on the silica surface, the NIR II contrast agents could actively target to liver tumors. Then tetrasulfide bonds can be broken during the silica framework decomposing in cytoplasm under high GSH concentration to result in NIR II fluorescence explosive recover. Benefiting from this specific response under tumor microenvironment, the NIR II signal in other organs was markedly reduced, while the signal-to-background ratio is prominently enhanced in tumors. Then, solid liver tumors were successfully resected under the guidance of our GSH responsive NIR II fluorescent imaging with no recurrence after 20-day of surgery. Meanwhile, by combining with the ignorable side effects, the Nd-based nanoprobes vastly improved the imaging resolution of tumor margin, opening a paradigm of NIR II fluorescent imaging-guided surgery.

NIR-II and visible fluorescence hybrid imaging-guided surgery via aggregation-induced emission fluorophores cocktails.

Fluorescence imaging-guided surgery is one of important techniques to realize precision surgery. Although second near-infrared window (NIR-II) fluorescence imaging has the advantages of high resolution and large penetration depth in surgical navigation, its major drawback is that NIR-II images cannot be detected by our naked eyes, which demands a high hand-eye coordination for surgeons and increases the surgical difficulty. On the contrary, visible fluorescence can be observed by our naked eyes but has poor penetration. Here, we firstly propose a kind of NIR-II and visible fluorescence hybrid navigation surgery assisted via a cocktail of aggregation-induced emission nanoparticles (AIE NPs). NIR-II imaging helps to locate deep targeted tissues and judge the residual, and visible fluorescence offers an easily surgical navigation. We apply this hybrid navigation mode in different animals and systems, and verify that it can accelerate surgical process and compatible with a visible fluorescence endoscopy. To deepen the understanding of lymph node (LN) labelling, the distribution of NPs in LNs after local administration is initially analyzed by NIR-II fluorescence wide-filed microscopy, and two fates of the NPs are summarized. An alternative strategy which combines indocyanine green and berberine is also reported as a compromise for rapidly clinical translation.

Does navigation still have avalue in trauma surgery?

Navigation systems are supposed to increase precision and support surgeons while they perform certain interventions. 2D, or nowadays 3D, systems are used in image-based approaches. Image-free navigation uses 3D printing. There are several studies on navigation procedures in trauma surgery. In contrast to limb surgery, the use of 3D navigation in pelvic and spine surgery is already well established. Navigation is especially regularly used to treat fractures of the posterior pelvic ring and for posterior stabilization of the cervical spine. To be able to utilize navigation systems optimally, the learning curve should be completed, and the technique should be used regularly. In addition, the surgeon should know the surgical technique without navigation in order to recognize potential errors of the navigation. Advantages include increased patient safety, reduction in radiation exposure and less invasive surgical procedures. However, among other disadvantages, initial costs are high.

Rim‐type indocyanine green fluorescence pattern in a child with undifferentiated embryonal sarcoma of the liver treated with navigation surgery

The authors declare that there is no conflict of interest.

Tumor-Targeting NIRF/MR Dual-Modal Molecular Imaging Probe for Surgery Navigation.

Multimodality imaging recognized as a promising monitoring strategy can serve the needs of accurate diagnosis and treatment of cancer by providing molecular and anatomic information about tumor sites. However, the probes based on multiple imaging modalities for surgery navigation remain limited due to poor biocompatibility and tumor targeting specificity. Herein, we present a small-molecule near-infrared fluorescence/magnetic resonance (NIRF/MR) imaging probe, Gd-NMC-3, covalently coupled with DCDSTCY and Gd-DOTA via butane diamine, for precise detection and intraoperative visualization. The in vitro and in vivo studies demonstrated that Gd-NMC-3 could be effectively accumulated in tumor sites as a bimodal imaging molecule exhibiting significant fluorescence accumulation and reasonable relaxation property in tumors with low cytotoxicity and good biocompatibility. Furthermore, Gd-NMC-3 was successfully applied to provide real-time visual navigation in LM3 orthotopic and subcutaneous tumor models to guide the resection of tumors. Importantly, no more fluorescence was observed in mice after operation, implying the total removal of tumor tissues. In conclusion, Gd-NMC-3 has great potential to be applied in the clinic based on its high resolution and sensitivity in tumor imaging.

Tumor-Background Ratio is an effective method to identify tumors and false-positive nodules in indocyanine-green navigation surgery for pediatric liver cancer.

BackgroundIndocyanine green (ICG) navigation surgery has been used for hepatoblastoma (HB) in children but the technique has been reported for using in other childhood liver cancers were rare. This article summarizes the application experience of ICG in HB and other childhood liver cancers in children and explores the role of fluorescence intensity measurement in identifying tumors.MethodsTo summarize the clinical experience of children with liver cancer treated by ICG navigation surgery. The tumor and its surrounding tissue were photographed by near infrared during the operation. The fluorescence intensity of tumors, ICG (+) lesions and the normal liver was measured, and the Tumor-Background Ratio (TBR) was calculated.ResultsA total of 11 children with liver cancer were injected intravenously with ICG 1 day before operation. With the help of ICG fluorescence navigation, there was no residual tumor at the surgical margin for all the children. Total fluorescence was seen in 2 cases, rim fluorescence in 2 cases, and partial fluorescence in 7 cases. 19 ICG false-positive nodules were found on the resection stump or residual liver tissue in 5 cases, and the TBR value of tumors was higher than that of false- positive nodules. 10 children have survived without disease.ConclusionICG navigation surgery is safe and feasible for liver cancer in children, which can enhance the visualization of the tumor during operation and provide more information about the location and boundaries of the tumor. This technique also has limitations, which can be affected by chemotherapy, tumor location, ICG administration regimen, and equipment. TBR is an effective method to identify tumor and non-cancerous lesions.

Annotation-guided encoder-decoder network for bone extraction in ultrasound-assisted orthopedic surgery

The patients and surgeons are usually exposed in massive ionizing radiation during fluoroscopy-based navigation orthopedic surgery. Comparatively, ultrasound-assisted orthopedic surgery could not only decrease the risk of radiation but also provide rich navigation information. However, due to the artifacts in ultrasound images, the extraction of bone structure from ultrasound sequences can be a particularly difficult task, which leads to some major challenges in ultrasound-assisted orthopedic navigation. In this paper, we propose an annotation-guided encoder-decoder network (AGN) to extract bone structure from the radiation-free ultrasound sequences. Specifically, the variability of the ultrasound probe's pose leads to the change of the ultrasound frame during the acquisition of ultrasound sequences. Therefore, a feature alignment module deployed in the AGN model is used to achieve reliable matching across ultrasound frames. Moreover, inspired by the interactive ultrasound analysis, where user annotated foreground information can help target extraction, our AGN model incorporates the annotation information obtained by Siamese networks. Experimental results validated that the AGN model not only produced better bone surface extraction than state-of-the-art methods (IOU: 0.92 versus. 0.88), but also achieved almost real-time extraction with the speed about 15 frames per second. In addition, the acquired bone surface further provided radiation-free 3D intraoperative bone structure for the intuitive navigation of orthopedic surgery.

Accuracy and application range of a splint integrated with a reference array and registration fiducial markers for mandibular navigation surgery in artificial skulls

ObjectiveNavigation surgery plays an important role in modern craniomaxillofacial surgery; however, its application to the mandible is more challenging. Although some reports have revealed feasibility of using the splint for mandibular navigation surgery, the accuracy and applicability of this method has not yet been clarified. Here, we report our evaluation of a splint integrated with a reference array and registration fiducial markers for mandibular navigation. MethodsOpen- and closed-position splints were manufactured using five artificial skulls. The splints were set on each skull, and computed tomography (CT) scans were acquired. Using the Digital Imaging and Communication in Medicine data, CT-based planning involved the registration and numbering of the position of accuracy evaluation markers and registration fiducial markers. The planning data were then transferred to the Kick navigation system to evaluate the registration accuracy of the splint. ResultsThe overall mean target registration errors (TREs) on the mandible of the open- and closed-position splints were 0.76 ± 0.35 and 0.75 ± 0.26 mm, respectively. The mean TREs of the operative and non-operative sides were 0.69 ± 0.22 and 0.87 ± 0.28 mm, respectively (p < 0.001). ConclusionsMandibular navigation using a custom-made splint has high accuracy within the range of the entire semi-lateral mandible on the operative side.

Accuracy of virtual planning and intraoperative navigation in zygomaticomaxillary complex fractures: A systematic review

ObjectiveThis systematic review aims to investigate the effect of virtual planning on the treatment of zygomaticomaxillary complex (ZMC) traumatology followed by intraoperative navigation. Furthermore, clinical outcomes following intraoperative navigation surgery or conventional surgery will be compared. Materials and methodsA systematic literature search was conducted in PubMed, Embase, Web-of-Science, and Cochrane on January 1st, 2022. Inclusion criteria were articles using preoperative three-dimensional (3D) virtual planning combined with intraoperative navigation or comparing these 3D methods with conventional methods. Furthermore, at least one of the following outcomes needed to be included in the article: technical accuracy of the procedure, preoperative planning time, operative time, number of fixation points, patient satisfaction, complications, or total costs of the intervention. ResultsFollowing the screening of 4478 articles, 17 were included. Five articles appeared to indicate a significantly better technical linear accuracy, one article reported better accuracy for rotation and two articles showed better accuracy in restoring orbital volume when using navigation. Nine articles investigated operative time with varying results. Seven articles calculated the additional costs, of which three concluded no extra cost while the others indicated high additional costs or questionable cost-effectiveness. ConclusionVirtual planning and intraoperative navigation technologies have the potential to assist maxillofacial trauma surgeons in reducing ZMC fractures significantly more accurately and restoring the facial contour in a less invasive manner at an acceptable cost. RegistrationThe protocol for this systematic review (CRD42020216717) was registered in the International Prospective Register of Systematic Reviews (PROSPERO).

Intraoperative Technology Use Improves Accuracy of Functional Safe Zone Targeting in Total Hip Arthroplasty.

Targets of acetabular inclination and anteversion have been suggested based on a patient's spinopelvic mobility. Current methods in total hip arthroplasty (THA) include manual instrumentation, computer-assisted navigation, and robotic-assisted surgery. This study aims to compare the accuracy of these 3 methods in targeting the functional safe zone. This is a prospective multicenter study including a series of 251 consecutive primary posterior THA patients from April 2019 to January 2021. Preoperative lateral standing and sitting spinopelvic radiographs were obtained. Each patient was classified using the Hip-Spine Classification. A functional safe zone plan was determined. Surgeons used their preferred method (manual instrumentation, computer-assisted, or robotic-assisted). Postoperative anteversion and inclination was measured and compared to the preoperative plan. Mean differences between preoperative and postoperative values were calculated. Welch's t-test was used to assess significant between-group differences with P < .05 considered significant. Of the 249 patients, there were 63 manual instrumentation, 68 computer-assisted navigation, and 118 robotic-assisted surgery. Robotic-assisted surgery (rTHA) was significantly more accurate in targeting anteversion (1±2) compared to manual instrumentation (mTHA; 7±6, P < .001) and computer-assisted navigation (cTHA; 6±6, P < .001). rTHA was also significantly more accurate in targeting inclination (1±1) compared to mTHA (8±7, P < .001) and cTHA (6±7, P < .001). Although cTHA had greater accuracy in targeting both inclination and anteversion compared to mTHA, these differences were not statistically significant. Robotic-assisted surgery was more accurate than both computer-assisted navigation and manual instrumentation in targeting the functional safe zone in primary THA. Further research is needed to evaluate the effect of improved accuracy on dislocation rates.

Real-time vascular anatomical image navigation for laparoscopic surgery: experimental study.

Recognition of the inferior mesenteric artery (IMA) during colorectal cancer surgery is crucial to avoid intraoperative hemorrhage and define the appropriate lymph node dissection line. This retrospective feasibility study aimed to develop an IMA anatomical recognition model for laparoscopic colorectal resection using deep learning, and to evaluate its recognition accuracy and real-time performance. A complete multi-institutional surgical video database, LapSig300 was used for this study. Intraoperative videos of 60 patients who underwent laparoscopic sigmoid colon resection or high anterior resection were randomly extracted from the database and included. Deep learning-based semantic segmentation accuracy and real-time performance of the developed IMA recognition model were evaluated using Dice similarity coefficient (DSC) and frames per second (FPS), respectively. In a fivefold cross-validation conducted using 1200 annotated images for the IMA semantic segmentation task, the mean DSC value was 0.798 (± 0.0161 SD) and the maximum DSC was 0.816. The proposed deep learning model operated at a speed of over 12 FPS. To the best of our knowledge, this is the first study to evaluate the feasibility of real-time vascular anatomical navigation during laparoscopic colorectal surgery using a deep learning-based semantic segmentation approach. This experimental study was conducted to confirm the feasibility of our model; therefore, its safety and usefulness were not verified in clinical practice. However, the proposed deep learning model demonstrated a relatively high accuracy in recognizing IMA in intraoperative images. The proposed approach has potential application in image navigation systems for unfixed soft tissues and organs during various laparoscopic surgeries.

The Use of Indocyanine Green (ICG) and Near-Infrared (NIR) Fluorescence-Guided Imaging in Gastric Cancer Surgery: A Narrative Review.

Near-infrared fluorescence imaging with indocyanine green is an emerging technology gaining clinical relevance in the field of oncosurgery. In recent decades, it has also been applied in gastric cancer surgery, spreading among surgeons thanks to the diffusion of minimally invasive approaches and the related development of new optic tools. Its most relevant uses in gastric cancer surgery are sentinel node navigation surgery, lymph node mapping during lymphadenectomy, assessment of vascular anatomy, and assessment of anastomotic perfusion. There is still debate regarding the most effective application, but with relatively no collateral effects and without compromising the operative time, indocyanine green fluorescence imaging carved out a role for itself in gastric resections. This review aims to summarize the current indications and evidence for the use of this tool, including the relevant practical details such as dosages and times of administration.

Adverse Events Associated With Image-Guided Sinus Navigation in Endoscopic Sinus Surgery: A MAUDE Database Analysis.

The utilization of image-guided navigation during endoscopic sinus surgery (ESS) has increased significantly since its introduction. However, the most common associated complications are still unknown. This study describes and analyzes adverse events related to image-guided ESS. Cross-sectional analysis. The Food and Drug Administration's 2018-2022 MAUDE database (Manufacturer and User Facility Device Experience). The MAUDE database was searched for all reports on adverse events involving sinus navigation systems used in ESS from 2018 to 2022. Reported events were reviewed and categorized. During the study period, there were 1857 adverse events from 1565 reports, which were divided into device-related (n = 1834, 98.8%) and patient-related (n = 23, 1.2%) complications. The most common device-related complications were nonfunctionality of the system (n = 512, 27.9%), device imprecision (n = 427, 23.3%), and device sensing problems (n = 277, 15.1%). The most common patient-related complications were cerebrospinal fluid (CSF) leak (n = 14, 60.9%), intracranial injury (n = 4, 17.4%), and bleeding/hemorrhage (n = 3, 13.1%). Imprecision was associated with increased risk of navigation abortion by the surgeon (odds ratio, 1.50 [95% CI, 1.38-1.65]; P < .001) and increased risk of CSF leak (odds ratio, 16.5 [95% CI, 3.66-74.0]; P < .001) as compared with other device-related complications. The most commonly reported device- and patient-related adverse events associated with image-guided sinus navigation systems were device nonfunction, imprecision, device sensing difficulties, and CSF leak. When imprecise navigation occurred, there was an increased likelihood of CSF leak and navigation abortion by the surgeon. Health care providers should be mindful of these possible complications when electing to use image-guided sinus navigation during ESS.

Accuracy assessment of marker recognition using ultra wide angle camera

Modern devices that support augmented reality technology are widely used in various fields of human activity, including medicine. Head mounted displays may provide an attractive alternative to traditional surgery navigation systems because allow users to stand at the first point of view and interact with objects in their surroundings naturally. Thus, the object of research in this study is recognition accuracy of fiducial markers in zones where ultra-wide angle camera distort the most. This is motivated by the need to increase user workspace for interaction with markers compare to the workspace provided with such popular augmented reality device as Microsoft HoloLens 2. In this study, the recognition accuracy is evaluated using ArUco square markers with taking into account different marker sizes and their positions in the camera view space. The marker positions include the center of the camera view space as well as such zones where lenses distort the most as top left, top right, bottom left, and bottom right corners. Obtained results show that recognition accuracy is good enough to be applicable for surgical navigation and failures referred to the distortion occurs are available in less than 0.2 % of all cases. This gives a possibility to increase workspace for interaction with markers compare to the Microsoft HoloLens 2. At the same time, the workspace for interaction could not reach the actual view space of the camera since recognition fails in cases where marker’s body is partially visible in the captured image (i. e., marker position is at the image boundaries).

Trends in the Charges and Utilization of Computer-Assisted Navigation in Cervical and Thoracolumbar Spinal Surgery.

Retrospective national database study. This study is conducted to assess the trends in the charges and usage of computer-assisted navigation in cervical and thoracolumbar spinal surgery. This study is the first of its kind to use a nationwide dataset to analyze trends of computer-assisted navigation in spinal surgery over a recent time period in terms of use in the field as well as the cost of the technology. Relevant data from the National Readmission Database in 2015-2018 were analyzed, and the computer-assisted procedures of cervical and thoracolumbar spinal surgery were identified using International Classification of Diseases 9th and 10th revision codes. Patient demographics, surgical data, readmissions, and total charges were examined. Comorbidity burden was calculated using the Charlson and Elixhauser comorbidity index. Complication rates were determined on the basis of diagnosis codes. A total of 48,116 cervical cases and 27,093 thoracolumbar cases were identified using computer-assisted navigation. No major differences in sex, age, or comorbidities over time were found. The utilization of computer-assisted navigation for cervical and thoracolumbar spinal fusion cases increased from 2015 to 2018 and normalized to their respective years' total cases (Pearson correlation coefficient=0.756, p =0.049; Pearson correlation coefficient=0.9895, p =0.010). Total charges for cervical and thoracolumbar cases increased over time (Pearson correlation coefficient=0.758, p =0.242; Pearson correlation coefficient=0.766, p =0.234). The use of computer-assisted navigation in spinal surgery increased significantly from 2015 to 2018. The average cost grossly increased from 2015 to 2018, and it was higher than the average cost of nonnavigated spinal surgery. With the increased utilization and standardization of computer-assisted navigation in spinal surgeries, the cost of care of more patients might potentially increase. As a result, further studies should be conducted to determine whether the use of computer-assisted navigation is efficient in terms of cost and improvement of care.

Generalized Point Set Registration With Fuzzy Correspondences Based on Variational Bayesian Inference

Point set registration (PSR) is an essential problem in surgical navigation and computer-assisted surgery (CAS). In CAS, PSR can be used to map the intraoperative surgical space with the preoperative volumetric image space. The performances of PSR in real-world surgical scenarios are sensitive to noise and outliers. This article proposes a novel point set registration approach where the additional features (i.e., the normal vectors) extracted from the point sets are utilized and the convergence of the algorithm is guaranteed from the theoretical perspective. More specifically, we formulate the PSR with normal vectors by generalizing the Bayesian coherent point drift (BCPD) into the 6-D scenario. The proposed algorithm is more accurate and robust to noise and outliers, and the theoretical convergence of the proposed approach is guaranteed. Our contributions of this article are summarized as follows. 1) The PSR problem with normal vectors is formally formulated through generalizing the BCPD approach. 2) The formulas for updating the parameters during the algorithm&#x2019;s iterations are given in closed forms. 3) Extensive experiments have been done to verify the proposed approach and specifically its significant improvements over the BCPD has been validated.

Abnormal spinopelvic mobility as a risk factor for acetabular placement error in total hip arthroplasty using optical computer-assisted surgical navigation system.

AimsNavigation devices are designed to improve a surgeon’s accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error.MethodsA total of 356 patients undergoing primary THA were prospectively enrolled from November 2016 to March 2018. Clinically relevant error using the CAS system was defined as a difference of > 5° between CAS and 3D radiological reconstruction measurements for acetabular component inclination and anteversion. Univariate and multiple logistic regression analyses were conducted to determine whether hypermobile (Δsacral slope(SS)stand-sit > 30°), or stiff (ΔSSstand-sit < 10°) spinopelvic mobility contributed to increased error rates.ResultsThe paired absolute difference between CAS and postoperative imaging measurements was 2.3° (standard deviation (SD) 2.6°) for inclination and 3.1° (SD 4.2°) for anteversion. Using a target zone of 40° (± 10°) (inclination) and 20° (± 10°) (anteversion), postoperative standing radiographs measured 96% of acetabular components within the target zone for both inclination and anteversion. Multiple logistic regression analysis controlling for BMI and sex revealed that hypermobile spinopelvic mobility significantly increased error rates for anteversion (odds ratio (OR) 2.48, p = 0.009) and inclination (OR 2.44, p = 0.016), whereas stiff spinopelvic mobility increased error rates for anteversion (OR 1.97, p = 0.028). There were no dislocations at a minimum three-year follow-up.ConclusionDespite high reliability in acetabular positioning for inclination in a large patient cohort using an optical CAS system, hypermobile and stiff spinopelvic mobility significantly increased the risk of clinically relevant errors. In patients with abnormal spinopelvic mobility, CAS systems should be adjusted for use to avoid acetabular component misalignment and subsequent risk for long-term dislocation.Cite this article: Bone Jt Open 2022;3(6):475–484.

Observational study of axilla treatment for breast cancer patients with 1 to 3 positive micrometastases or macrometastases in sentinel lymph nodes.

e12576 Background: From the results of ACOSOG Z0011, IBCSG23-01 and AMAROS trials, axilla surgery in node-positive breast cancer (BC) tends to be less invasive with sentinel node biopsy (SNB) followed by adjuvant therapy and regional node irradiation (RNI). However, optimized axilla treatment including SNB without RNI is still debated. The Japanese Society for Sentinel Node Navigation Surgery conducted a multi-institutional prospective cohort study to compare SNB with SNB followed by axillary lymph node dissection (ALND) in cases with positive-sentinel lymph nodes (SLN)(UMIN No. 000011782, Jpn J Clin Oncol, p.876-9, 2014). Methods: Female BC patients with cT1-3N0-1M0 were eligible. When 1 to 3 positive micrometastases or macrometastases in SLN were confirmed by histological or molecular diagnosis, SNB alone or additional ALND had been decided by physician’s discretion. Primary chemotherapy before or after SNB was acceptable for registration. Lymph node sampling was also allowed in the SNB group. Cases with bilateral BC, isolated tumor cells only in SLN, past history of invasive cancer within 5 years at the registration were ineligible. The primary endpoint was the 5-year recurrence rate of regional node (RN) in the SNB group. The secondary endpoint was overall survival (OS). We planned to collect 240 patients to reject that the 5-year recurrence rate of RN was more than 10% assuming the rate 5%. To compare the SNB group and ALND group, the propensity score matching (PSM) was performed. Matching variables were initial treatment, metastatic size and numbers of SLN, clinical stage, age, body mass index, menopausal status, family history, past history of invasive cancer, breast surgery. Results: Eight-hundred eighty cases had been registered between 2013 and 2016. In the 871 eligible cases, 308 cases were the SNB group. At the median follow-up of 6.3 years, 5-year recurrence rate of RN was 2.7% [95% confidence interval, 1.4% to 5.4%] and 5-year OS was 97.6% [94.9% to 98.8%]. After PSM, 209 cases were matched in the SNB and ALND group. Among them, 343 cases (82%) received operation at initial treatment. Partial and total mastectomy was performed in 225 (54%) and 193 cases (46%), respectively. One-positive SLN was recorded in 366 cases (88%), 2 in 48 (11%) and 3 in 4 (1%). Macrometastases and micrometastases in SLN were diagnosed in 271 (65%) and 147 cases (35%), respectively. Three-hundred seventy-six cases (90%) belonged to luminal-like subtype. RNI was underwent in 42 cases (20%) of the SNB group and 13 cases (6%) of the ALND group. Five-year recurrence rate of RN was 2.1% [0.8% to 5.5%] and 2.0% [0.8% to 5.3%] for the SNB and ALND group, respectively. Conclusions: Our series suggests that RNI is not necessary for regional control in cases with 1 to 3 positive SLN. In conclusion, SNB alone is acceptable in cases with fewer metastatic SLN. Clinical trial information: UMIN No. 000011782.