Three-dimensional computed tomography-guided excision of an intrathoracic giant thymoma with elongated thymic vessels

We report the case of an intrathoracic giant thymoma with elongated thymic vessels, which was successfully resected under three-dimensional computed tomography guidance. A large, left-sided intrathoracic mass was incidentally found in a 41-year-old woman during a routine work-up for uterine cancer. Six vessels were noted arising from the tumor, five of which were connected to the anterosuperior mediastinum. The vasculature suggested that the tumor originated from the thymus and grew into the left pleural cavity, which pulled and elongated the associated vessels. Preoperative computed tomography imaging demonstrated that these vessels were located behind the tumor, which increased the risk for catastrophic intraoperative bleeding. We created a detailed surgical plan using our preoperative computed tomography data and successfully excised the tumor using intraoperative three-dimensional computed tomography guidance. Histopathological examination revealed a type AB thymoma without capsular invasion. This case highlighted the role of preoperative planning and intraoperative imaging in resecting an intrathoracic giant thymoma safely. In the video, we demonstrate how we performed the procedure under three-dimensional navigation.

Fracture planning is easy: Development of a basic method of digital planning based on the traditional pencil and paper technique

INTRODUCTION

Preoperative planning constitutes a fundamental tool in the management of fractures; however, its practical application is far from the desired, perhaps due to the absence of a basic and simple method, adapted to the current times. We describe a digital planning method, halfway between the traditional and the technological, which preserves its educational essence, allows the understanding of the fracture and the individualization of the osteosynthesis.

MATERIAL AND METHODS

After the initial analysis of the fracture and the patient's characteristics, different measurements are made on X-ray and CT images with a digital medical imaging software. These images are then copied into a presentation program (Microsoft® PowerPoint or Keynote ©Apple Inc.), in which the main fragments and fracture lines are traced with the computer pointer. These are subsequently moved into a reduced position and the implants for internal fixation are graphically represented together with a guide of the surgical strategy.

RESULTS

We show 4 cases of different types of fractures operated through reduction and osteosynthesis after preoperative planning according to the described method. The basic points for the surgical planning, logistics, tactics and postoperative radiological results of each case are detailed.

CONCLUSIONS

Despite rise of advanced planning software, traditional paper and pencil methods are still fundamental, even more so for the trauma surgeon in training. The digital planning method described is very appropriate for this purpose, as it combines the advantages of both methods: simplicity, accessibility, quickness, low-cost, reproducibility, educational character, efficiency and possibility of simulation, corrections and reuse of cases.

Clinical and radiological outcomes of endoscopic foraminoplasty and decompression assisted with preoperative planning software for lumbar foraminal stenosis

PURPOSE

To assess the clinical and radiological outcomes of using endoscopic foraminoplasty and decompression assisted with a preoperative planning software in the treatment of lumbar foraminal stenosis.

METHODS

This retrospective study included 43 patients with lumbar foraminal stenosis (Jan 2018 and June 2019). These patients were divided into two groups. Patients in the conventional group (group A) underwent endoscopic lumbar foraminoplasty and decompression. Patients in the experimental group (group B) underwent the same surgery assisted with a preoperative software. The total operation time, puncture-channel establishment time, and the number of intraoperative fluoroscopic images taken were recorded. The Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were administered preoperatively and postoperatively (at 1-month, 3-month, and 12-month follow-up). The modified MacNab criteria were used to assess the global outcome at 12-month follow-up.

RESULTS

Patients in group B had shorter operation time, puncture-channel establishment time, and less number of intraoperative fluoroscopic images taken, as compared with group A. The VAS and ODI scores were significantly lower than pre-operation for both groups at all follow-ups. No significant difference was observed between these two groups. Based on the modified MacNab criteria, the excellent-to-good rate was 86.4% in group A and 90.5% in group B, respectively. After the operation, no patients had residual osteophytes in group B, while two patients still had residual osteophytes and foraminal stenosis in group A.

CONCLUSION

For endoscopic surgery treating lumbar foraminal stenosis, using preoperative planning software could reduce the puncture-channel establishment time, operation time, and the number of intraoperative fluoroscopic images taken without affecting the clinical outcomes.

Precision and accuracy of pre-surgical planning of non-cemented total hip replacement with calibrated digital images and acetates

Background

When approaching a joint replacement procedure, pre-surgical planning is essential to predict an accurate estimation of implant size and position. There are currently two methods to achieve it, analog and digital. The present study aims to demonstrate how the hybrid technique is accurate and precise for pre-surgical planning in a non-cemented total hip replacement.

Methods

Concordance-type study is used against a gold standard, as well as inter- and intra-observer consistency evaluation of two orthopedic surgeons and two orthopedic surgery residents. Accuracy was calculated with the intra-class correlation coefficient (ICC). Afterwards, the same calculation was done considering a margin of error with one size more and one less.

Results

Thirty-eight patients were included in the study: 19 women and 19 men. Twenty-two prostheses (57.89%) were right-sided and 16 were left (42.11%). Twelve prostheses (31.57%) were Stryker and 26 Johnson & Johnson (68.43%). Acetabular cup correlation compared with the gold standard was moderate: ICC reported 0.45 (95% CI, 0.15–0.76). When adjusted by ± 1 size, ICC was 0.48 (95% CI, 0.18–0.79). On the other hand, results from the femoral stem reported ICC 0.85 (95% CI, 0.07–0.98). When adjusted by ± 1 size, ICC was 0.86 (95% CI, 0.06–0.99).

Conclusions

Hybrid templating is a reliable substitute for analog or digital planning. It is quick, inexpensive, accurate, and better results are observed in the femoral component regardless the level of expertise of the evaluator.

Level of evidence

Grade IV

Homemade 3D mirror imaging models utility for surgical treatment of complex fractures of scapula

The treatment of complex articular scapular fractures requires obtaining an anatomic reduction. The experience of the surgeon and the surgical skills needed are still the most important aspect in this surgical field. 3D printed models at a 1:1 scale provides tactile and visual experience. We used a specular healthy scapula (reverse engineering) as a reliable template for preoperative planning. We pre-contour plates directly over a printed mold, for direct application, without further corrections during the surgical procedure. This reduces improvisation during surgery, the risks of complications and the total costs while improving the accuracy of the anatomical restoration of the native glenopolar angle derived from the indirect reduction of the fracture. Until recently, the use of RP (rapid prototyping) models for managing complex fractures required contracting the services provided by external companies, with the constraints posed on cost and time. We made the whole process ourselves in a DIY mode: from the post-processed radiological images to the 3D model printing, pre contoured plates and surgical simulation.

The "STARS-CT-MADE" Study: Advanced Rehearsal and Intraoperative Navigation for Skull Base Tumors

BACKGROUND

Skull base meningiomas represent a challenge for neurosurgeons, and the procedures are typically performed by experienced neurosurgeons, thus limiting resident training. A new simulation and rehearsal device can be used as an aid for senior surgeons during these operations and serve as a training tool for junior surgeons.

METHODS

Forty patients harboring an anterior/middle fossa meningioma were recruited. Surgical Theater, a rehearsal/simulation platform, was used for preoperative planning and intraoperative 3D navigation on 20 patients (CT-MADE group), while the remaining (control group) underwent a traditional navigation. Qualitative comparisons between the 2 groups were made with regard to surgical procedure and patient outcome. Satisfaction questionnaires were completed by expert neurosurgeons and residents to assess the overall usefulness of the platform. Furthermore, the surface of the simulated craniotomy performed during the planning was compared with the one actually performed during surgery in order to evaluate the reliability of the planning.

RESULTS

No differences between the 2 groups were found (surgery duration: P = 0.4; visual impairment: P = 0.56). Both residents and senior neurosurgeons enjoyed using the platform for intraoperative navigation and planning; simulated craniotomies were significantly smaller as compared with the real ones (P = 0.009), probably because it was not intuitive to depict the exact margins of the operculum with the platform.

CONCLUSION

Surgical Theater helped residents to improve their anatomic and procedural comprehension and was deemed as a useful aid to safely perform some demanding neurosurgical procedures, by both senior and junior surgeons.

A study of three-dimensional reconstruction and printing models in two cases of soft tissue sarcoma of the thigh

PURPOSE

The aim of our study was to demonstrate the value of three-dimensional (3D) reconstruction and three-dimensional printing (3DP) models in two cases of soft tissue sarcoma (STS) of the thigh.

MATERIALS AND METHODS

Two patients with STS were recruited and underwent enhanced CT and MRI scans. Then, the 3D models were reconstructed and printed using the obtained data, and five experts were invited to assess the segmentation quality. In addition, 34 junior, intermediate and senior general surgeons were recruited to demonstrate the value of 3D models in preoperative planning and invited five surgeons to complete the assessment of 3D models-assisted intraoperative navigation. Finally, 32 interns were enrolled to explore the significance of 3D models in medical education.

RESULTS

All experts agree with the accuracy of the 3D models. The application of 3D models in preoperative planning improved the understanding of general surgeons (P = 0.000, P = 0.000, P = 0.000). After the planning tools were exchanged between the two groups, senior surgeons in group A showed more significant improvements in performance than junior and intermediate surgeons in group A (P = 0.001, P = 0.006). Surgeons unanimously agree on the value of 3D models in intraoperative navigation. When applied for the education of medical interns, these models could enhance their understanding of pathologic anatomies (P = 0.036).

CONCLUSION

In two operations for STS of the thigh with complex adjacencies, our study demonstrates that 3D models are of great value for preoperative planning, intraoperative navigation and medical education. More importantly, these models were more helpful to senior general surgeons.

Effect of the underlying cadaver data and patient-specific adaptation of the femur and pelvis on the prediction of the hip joint force estimated using static models

The prediction of the hip joint force (HJF) is a fundamental factor for the prevention of edge loading in total hip arthroplasty. Naturally, the loading of the liner of the acetabular component depends on the HJF acting on the artificial joint. In contrast to dynamic musculoskeletal models, static models for HJF prediction do not require motion analysis of the patient. However, patient-specific adaptability and validity of static models have to be scrutinized. In this study, a modular framework for HJF prediction using static models is introduced to compare the results of different cadaver templates that are the basis of most static and dynamic models, and different scaling laws for the patient-specific adaptation with in vivo HJF of ten patients for one-leg stance and level walking. The results revealed the significant effect of the underlying cadaver template used for the prediction of the HJF (p < 0.01). A higher degree of patient-specific scaling of the cadaver template often did not significantly reduce the prediction error. Three static models with the lowest prediction errors were compared to results of dynamic models from literature. The prediction error of the peak HJF of the static models (median absolute errors below 15% body weight in magnitude and below 5° in direction) was similar in magnitude and even smaller in direction compared to dynamic models. The necessary reduction of a load-based target zone for the prevention of edge loading due to the uncertainty of the HJF prediction has to be considered in the preoperative planning. The framework for HJF prediction is openly accessible at https://github.com/RWTHmediTEC/HipJointForceModel.

Preoperative Planning Modalities for Meningoencephalocele: New Proof of Concept

OBJECTIVE

Late surgical correction of meningoencephalocele is a rare scenario that remains challenging for surgeons. Three-dimensional models can mimic the correct anatomical relationships, and technological systems have brought advances to medicine. This study aims to present a novel preoperative planning modality that combines augmented reality with a hybrid model for complex malformation associated with late correction.

METHODS

The present report describes a case of frontoethmoidal encephalocele of a 10-year-old girl. Two different methods for planning the approach were developed: 1) a hybrid hands-on model and 2) augmented reality, using a cell phone app and headset display. The customized hybrid model was created based on patient's imaging. The augmented reality app was developed with a real-time interface.

RESULTS

The hybrid model recreated anatomic alterations, thereby allowing a multidisciplinary team to determine an appropriate surgical approach. All aspects of the surgical procedure were simulated. A pre- to postoperative comparison was made, which emphasized benefit of tridimensional anatomical relationships using augmented reality tool and its role in preoperative planning.

CONCLUSIONS

The authors believe this new multimodality preoperative platform could be a useful method to improve multidisciplinary discussion as well as a powerful tool for teaching and planning.

Patient-specific statistical shape modeling for optimal spinal sagittal alignment in lumbar spinal fusion

PURPOSE

The present study compared patients developing ASD after L4/5 spinal fusion with a control group using a patient-specific statistical shape model (SSM) to find alignment-differences between the groups.

METHODS

This study included patients who had undergone spinal fusion at L4/5 and either remained asymptomatic (control group; n = 25, follow-up of > 4 years) or required revision surgery for epifusional ASD (n = 22). Landmarks on preoperative and postoperative lateral radiographs were annotated, and the optimal spinal sagittal alignment was calculated for each patient. The two-dimensional distance from the SSM-calculated optimum to the actual positions before and after fusion surgery was compared.

RESULTS

Postoperatively, the additive mean distance from the SSM-calculated optimum was 86.8 mm in the ASD group and 67.7 mm in the control group (p = 0.119). Greater differences were observed between the groups with a larger distance to the ideal in patients with ASD at more cranial levels. Significant difference between the groups was seen postoperatively in the vertical distance of the operated segment L4. The patients with ASD (5.69 ± 3.0 mm) had a significant greater distance from the SSM as the control group (3.58 ± 3.5 mm, p = 0.034).

CONCLUSION

Patients with ASD requiring revision after lumbar spinal fusion have greater differences from the optimal spinal sagittal alignment as an asymptomatic control group calculated by patient-specific statistical shape modeling. Further research might help to understand the value of SSM, in conjunction with already established indexes, for preoperative planning with the aim of reducing the risk of ASD.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Is analog preoperative planning still applicable?-comparison of accuracy of analog and computer preoperative planning methods in total hip arthroplasty

Background

Preoperative planning is an integral part of total hip arthroplasty and has a significant impact on surgical technique and clinical outcome. The variety of types and sizes of endoprosthesis components makes the procedure more demanding and generates a need for accurate preoperative planning. The objective of this study was to analyze an analog method of preoperative planning of primary total hip arthroplasty based on templates overlaying on preoperative radiograms and compare its accuracy for predicting the size, both the stem and cup, with computer planning methods.

Methods

A retrospective cohort study based on 360 X-ray images of hip joints in 348 patients qualified for total hip arthroplasty between 2018 and 2019. The study group consisted of 136 men and 212 women, with an average age of 65 years (56 to 85 years). Material included both cementless and cemented endoprostheses.

Results

In the analyzed material, the accuracy of cup planning using the analog method was 85% (P<0.001) and 77% (P<0.001) in the planning of stem size. However, using the computer method, planning accuracy was 82% (P<0.001) for the cup and 72% (P<0.001) for the stem.

Conclusions

Both methods of preoperative planning remain effective. The analog method of preoperative planning is simple, precise, and repeatable in choosing the type and size of endoprosthesis components with an accuracy of 85% and 77% for the cup and stem respectively. The accuracy of planning depends on the type of endoprosthesis and in the case of the cemented endoprosthesis, it is lower than in cementless.

Point-of-care manufacturing: a single university hospital's initial experience

Background

The integration of 3D printing technology in hospitals is evolving toward production models such as point-of-care manufacturing. This study aims to present the results of the integration of 3D printing technology in a manufacturing university hospital.

Methods

Observational, descriptive, retrospective, and monocentric study of 907 instances of 3D printing from November 2015 to March 2020. Variables such as product type, utility, time, or manufacturing materials were analyzed.

Results

Orthopedic Surgery and Traumatology, Oral and Maxillofacial Surgery, and Gynecology and Obstetrics are the medical specialties that have manufactured the largest number of processes. Working and printing time, as well as the amount of printing material, is different for different types of products and input data. The most common printing material was polylactic acid, although biocompatible resin was introduced to produce surgical guides. In addition, the hospital has worked on the co-design of custom-made implants with manufacturing companies and has also participated in tissue bio-printing projects.

Conclusions

The integration of 3D printing in a university hospital allows identifying the conceptual evolution to “point-of-care manufacturing.”

Preoperative volume estimation in transverse upper gracilis flap surgery: A pilot study

BACKGROUND

The transverse upper gracilis (TUG) flap provides a good alternative to the gold standard DIEP in breast reconstruction. However, flap volume estimates are subjective, making preoperative planning potentially challenging.

STUDY AIM

To derive a reliable, accurate, and reproducible mathematical algorithm for the preoperative calculation of TUG flap volumes.

MATERIALS AND METHODS

Nineteen consecutive patients with 30 TUG flaps were prospectively included. On the assumption that the TUG flap resembles two isosceles prisms, the formula of the volume of a prism was used to calculate their preoperative flap weights. These were then intraoperatively compared to the actual flap weights. A regression equation was calculated from the correlation analysis of 10 random flaps. This was then applied to the remaining 20 flaps to assess for improved reliability and weight prediction accuracy.

RESULTS

The prism volume equation used to clinically calculate flap volumes was: Geometric flap weight = (h₁bT)/2+ (h₂bT)/2, (h = height, b = base, T = flap thickness); all in centimetres. Geometric and actual flap weights were found to be significantly correlated (r² = 0.977) generating the following regression formula: predicted TUG weight = 0.924 × geometric weight + 26.601. When this was applied to the remaining 20 flaps, no significant difference was found (p = 0.625) between predicted and actual flap weights, demonstrating an increased accuracy of predicting flap volume.

CONCLUSION

The proposed formula provides the clinician with a more accurate and reliable estimation of available TUG flap volume and may potentially aid with preoperative planning and patient consultations.

Conceptual evolution of 3D printing in orthopedic surgery and traumatology: from "do it yourself" to "point of care manufacturing"

BACKGROUND

3D printing technology in hospitals facilitates production models such as point-of-care manufacturing. Orthopedic Surgery and Traumatology is the specialty that can most benefit from the advantages of these tools. The purpose of this study is to present the results of the integration of 3D printing technology in a Department of Orthopedic Surgery and Traumatology and to identify the productive model of the point-of-care manufacturing as a paradigm of personalized medicine.

METHODS

Observational, descriptive, retrospective and monocentric study of a total of 623 additive manufacturing processes carried out in a Department of Orthopedic Surgery and Traumatology from November 2015 to March 2020. Variables such as product type, utility, time or materials for manufacture were analyzed.

RESULTS

The areas of expertise that have performed more processes are Traumatology, Reconstructive and Orthopedic Oncology. Pre-operative planning is their primary use. Working and 3D printing hours, as well as the amount of 3D printing material used, vary according to the type of product or material delivered to perform the process. The most commonly used 3D printing material for manufacturing is polylactic acid, although biocompatible resin has been used to produce surgical guides. In addition, the hospital has worked on the co-design of customized implants with manufacturing companies.

CONCLUSIONS

The integration of 3D printing in a Department of Orthopedic Surgery and Traumatology allows identifying the conceptual evolution from "Do-It-Yourself" to "POC manufacturing".

Virtual Reality in Preoperative Planning of Adolescent Idiopathic Scoliosis Surgery Using Google Cardboard

OBJECTIVE

Preoperative planning in spine surgery is a fundamental step of the surgical workup and is often assisted by direct visualization of anatomical 2-dimensional images. This process is time-consuming and may excessively approximate the 3-dimensional (3D) nature of spinal anatomy. Virtual reality (VR) is an emerging technology capable of reconstructing an interactive 3D anatomical model that can be freely explored and manipulated.

METHODS

Sixty patients with adolescent idiopathic scoliosis underwent correction of the scoliotic curve by posterior arthrodesis after preoperative planning using traditional on-screen visualization of computed tomography scans (control group, n = 30) or exploration of a 3D anatomical model in VR using Google Cardboard (Google Inc.) (VR group, n = 30). Mean operative time, blood loss, length of hospital stay, and surgeon's satisfaction were assessed after surgery.

RESULTS

The use of VR led to a significant decrease in operative time and bleeding while increasing the surgeon's satisfaction compared to the control group.

CONCLUSION

Preoperative planning with VR turned out to be effective in terms of operative time and blood loss reduction. Moreover, such technology proved to be reproducible, costeffective, and more satisfactory compared to conventional planning.

Differences in preoperative planning for high-tibial osteotomy between the standing and supine positions

Introduction

Previous studies have reported that alignment changes depend on the patient’s position in orthopedic surgery. However, it has not yet been well examined how the patient’s position affects the preoperative planning in high-tibial osteotomy (HTO). Therefore, the aim of this study was to investigate the effects of the patient’s position on preoperative planning in HTO.

Materials and methods

A total of 60 knees in 55 patients who underwent HTO were retrospectively examined. Virtual preoperative planning for medial open-wedge HTO (OWHTO), lateral closed-wedge HTO (CWHTO), and hybrid CWHTO were performed by setting the percentage of the weight-bearing line (%WBL) at 62% as an optimal alignment. The correction angle differences between the supine and standing radiographs were measured. The virtual %WBL (v%WBL) was determined by applying the correction angle obtained from the standing radiograph to the supine radiograph. The %WBL discrepancy (%WBLd) was calculated as v%WBL − 62 (%) to predict the possible correction errors during surgeries. A single regression analysis was performed to examine the correlation between the correction angle difference and %WBLd.

Results

The mean correction angle was significantly higher when the preoperative planning was based on standing radiographs than when based on supine radiographs (P < 0.001), and the mean difference was 2.2 ± 1.5°. The difference between the two conditions in the medial opening gaps for OWHTO, lateral wedge sizes (mm) for CWHTO, and hybrid CWHTO were 2.6 ± 2.0, 2.3 ± 1.6, and 1.9 ± 1.4, respectively. The mean v%WBL was 71.2% ± 7.3%, and the mean %WBLd was 10.1% ± 7.4%. A single regression analysis revealed a linear correlation between the correction angle difference and %WBLd (%WBLd = 4.72 × correction angle difference + 0.08). No statistically significant difference in the parameters was found between the supine and standing radiographs postoperatively.

Conclusions

We found significant differences in the estimated correction angles between the supine and standing radiographs in the planning for HTO. Therefore, surgeons should carefully consider the difference between supine and standing radiographs and estimate the possible correction error during surgery when planning a HTO.

In situ cross-sectional area of the quadriceps tendon using preoperative magnetic resonance imaging significantly correlates with the intraoperative diameter of the quadriceps tendon autograft

PURPOSE

Preoperative assessment to determine the sizes of potential autografts is necessary for individualized anterior cruciate ligament reconstruction (ACLR). However, no study has investigated the prediction of the intraoperative diameter of the quadriceps tendon (QT) autograft based upon preoperative imaging. This study investigated the correlation between the intraoperative diameter of a QT autograft and in situ thickness or cross-sectional area (CSA) measured using preoperative MRI.

METHODS

Thirty-one knees of 31 patients (mean age 20.9 ± 5.0 years) who underwent individualized anatomic ACLR using all soft tissue QT autograft were included retrospectively. At 15 mm proximal to the superior pole of the patella, the maximum QT thickness was assessed in the sagittal plane and the CSA was assessed at the central 10 mm of the QT in the axial plane. The angle between the axial plane and a line perpendicular to the QT longitudinal axis was used to calculate an adjusted CSA using a cosine function. Intraoperatively, each QT autograft was harvested with 10 mm width and the diameter was measured using a graft sizing device.

RESULTS

Intra- and inter-observer reliabilities of all measurements using preoperative MRI were excellent (intra-class correlation coefficient, 0.833-0.970). Significant correlations were observed between the thickness, CSA, or adjusted CSA, and the intraoperative diameter (R = 0.434, 0.607, and 0.540, respectively; P < 0.05).

CONCLUSIONS

The CSA correlated most strongly with the QT autograft diameter. For individualized anatomic ACLR, measuring in situ CSA can be useful for preoperative planning of appropriate graft choices prior to surgery.

LEVEL OF EVIDENCE

III.

Three-dimensional assessment of patellofemoral anatomy: Reliability and reference ranges

BACKGROUND

Three-dimensional (3D) imaging and analysis offer new possibilities in preoperative diagnostics and surgical planning. Simultaneous 3D analysis of the joint angles and the patellofemoral anatomy allow for a realistic assessment of bony pathologies in patients with patellofemoral complaints. This study aims to develop a standardized and validated assessment of the 3D patellofemoral morphology and to establish reference ranges.

METHODS

Thirteen patellofemoral anatomic landmarks were defined on 3D bone models of the lower limbs based on computer tomography data and evaluated regarding inter- and intra-observer variability. Further, 60 3D models of the lower limbs of young subjects without any previous knee operation/injury were assessed and rescaled reference values for relevant patellofemoral indices were obtained.

RESULTS

The mean inter- and intra-observer deviation of all landmarks was below 2.3 mm. The interobserver intraclass correlation coefficient (ICC) was between 0.8 and 1.0 and the intra-observer ICC between 0.68 and 0.99 for all patellofemoral parameters. The calculated reference ranges are: Insall-Salvati index 1.0-1.4; patella tilt 6-18°; patella shift -4 to 3 mm; patella facet angle 118-131°; sulcus angle 141-156°; trochlear depth 3-6 mm; tibial-tuberosity to trochlear groove distance(TT-TG) 2D 14-21 mm; TT-TG 3D 11-18 mm; lateral trochlear inclination 13-23°; trochlear facet angle 43-65°.

CONCLUSION

The demonstrated 3D analysis of the patellofemoral anatomy can be performed with high inter- and intra-observer correlation. Applying the obtained reference ranges and using existing 3D assessment tools for lower limb alignment, a preoperative 3D analysis and planning for complex knee procedures now is possible.

Value of 3D preoperative planning for primary total hip arthroplasty based on artificial intelligence technology

Background

Accurate preoperative planning is an important step for accurate reconstruction in total hip arthroplasty (THA). Presently, preoperative planning is completed using either a two-dimensional (2D) template or three-dimensional (3D) mimics software. With the development of artificial intelligence (AI) technology, AI HIP, a planning software based on AI technology, can quickly and automatically identify acetabular and femur morphology, and automatically match the optimal prosthesis size. However, the accuracy and feasibility of its clinical application still needs to be further verified. The purposes of this study were to investigate the accuracy and time efficiency of AI HIP in preoperative planning for primary THA, compared with 3D mimics software and 2D digital template, and further analyze the factors that influence the accuracy of AI HIP.

Methods

A prospective study was conducted on 53 consecutive patients (59 hips) undergoing primary THA with cementless prostheses in our department. All preoperative planning was completed using AI HIP as well as 3D mimics and 2D digital template. The predicted component size and the actual implantation results were compared to determine the accuracy. The templating time was compared to determine the efficiency. Furthermore, the potential factors influencing the accuracy of AI HIP were analyzed including sex, body mass index (BMI), and hip dysplasia.

Results

The accuracy of predicting the size of acetabular cup and femoral stem was 74.58% and 71.19%, respectively, for AI HIP; 71.19% (P = 0.743) and 76.27% (P = 0.468), respectively, for 3D mimics; and 40.68% (P < 0.001) and 49.15% (P = 0.021), respectively, for 2D digital templating. The templating time using AI HIP was 3.91 ± 0.64 min, which was equivalent to 2D digital templates (2.96 ± 0.48 min, P < 0.001), but shorter than 3D mimics (32.07 ± 2.41 min, P < 0.001). Acetabular dysplasia (P = 0.021), rather than sex and BMI, was an influential factor in the accuracy of AI HIP templating. Compared to patients with developmental dysplasia of the hip (DDH), the accuracy of acetabular cup in the non-DDH group was better (P = 0.021), but the difference in the accuracy of the femoral stem between the two groups was statistically insignificant (P = 0.062).

Conclusion

AI HIP showed excellent reliability for component size in THA. Acetabular dysplasia may affect the accuracy of AI HIP templating.

The Variation of the Pelvis in Unilateral Crowe Type IV Developmental Dysplasia of the Hip

OBJECTIVE

To investigate variation of the pelvis in unilateral Crowe type IV developmental dysplasia of the hip (DDH) and analyze the reliability of pelvic landmarks.

METHODS

We retrospectively received preoperative anteroposterior pelvic radiographs for 89 adult patients with unilateral Crowe type IV DDH at our institution between September 2008 and May 2019. Forty-eight patients without a false acetabulum was type IVA and 41 with a false acetabulum was type IVB. The heights of the ilium, acetabulum, and ischium areas in affected and unaffected sides were measured. The ratios of the three areas in entire pelvis are calculated. The discrepancies of bilateral iliac crest, inferior sacroiliac articulation, teardrop, and ischial tuberosity on the bisector of the pelvis were also measured.

RESULTS

The mean heights of the ilium, acetabulum, ischium areas in the affected side were 74.4, 88.6, and 37.0 mm, respectively, in type IVA group and 77.7, 83.5, and 37.8 mm, respectively, in type IVB group. The heights in the unaffected side were 82.1, 84.6, and 43.8 mm, respectively, in type IVA group and 84.6, 82.0, and 44.0 mm, respectively, in type IVB group. The ratios of the ilium, acetabulum, ischium areas in affected side of Crowe type IVA group were 0.37, 0.44, and 0.19, respectively, and the ratios in unaffected side were 0.39, 0.40, and 0.21, respectively. The ratios in affected side of Crowe type IVB group were 0.39, 0.42, and 0.19, respectively, and the ratios in unaffected side were 0.40, 0.39, and 0.21, respectively. The discrepancies of bilateral iliac crest, inferior sacroiliac articulation, teardrop, and ischial tuberosity on the line of the bisector of the pelvis in Crowe type IVA group were 5.6, 5.2, 2.0, and 7.1 mm, respectively. Those in Crowe type IVB group were 8.1, 3.5, 3.5, and 4.9 mm, respectively.

CONCLUSIONS

Pelvic asymmetry was a common occurrence in unilateral Crowe type IV DDH in adults. Furthermore, it should be reliable to use teardrop as pelvic landmark to balance leg length discrepancy in preoperative planning.

Planning Brain Tumor Resection Using a Probabilistic Atlas of Cortical and Subcortical Structures Critical for Functional Processing: A Proof of Concept

BACKGROUND

Functional preoperative planning for resection of intrinsic brain tumors in eloquent areas is still a challenge. Predicting subcortical functional framework is especially difficult. Direct electrical stimulation (DES) is the recommended technique for resection of these lesions. A reliable probabilistic atlas of the critical cortical epicenters and subcortical framework based on DES data was recently published.

OBJECTIVE

To propose a pipeline for the automated alignment of the corticosubcortical maps of this atlas with T1-weighted MRI.

METHODS

To test the alignment, we selected 10 patients who underwent resection of brain lesions by using DES. We aligned different cortical and subcortical functional maps to preoperative volumetric T1 MRIs (with/without gadolinium). For each patient we quantified the quality of the alignment, and we calculated the match between the location of the functional sites found at DES and the functional maps of the atlas.

RESULTS

We found an accurate brain extraction and alignment of the functional maps with both the T1 MRIs of each patient. The matching analysis between functional maps and functional responses collected during surgeries was 88% at cortical and, importantly, 100% at subcortical level, providing a further proof of the correct alignment.

CONCLUSION

We demonstrated quantitatively and qualitatively the reliability of this tool that may be used for presurgical planning, providing further functional information at the cortical level and a unique probabilistic prevision of distribution of the critical subcortical structures. Finally, this tool offers the chance for multimodal planning through integrating this functional information with other neuroradiological and neurophysiological techniques.

Clinical Implementation of In-House Developed MR-Based Patient-Specific 3D Models of Liver Anatomy

Knowledge of patient-specific liver anatomy is key to patient safety during major hepatobiliary surgery. Three-dimensional (3D) models of patient-specific liver anatomy based on diagnostic MRI images can provide essential vascular and biliary anatomical insight during surgery. However, a method for generating these is not yet publicly available. This paper describes how these 3D models of the liver can be generated using open source software, and then subsequently integrated into a sterile surgical environment. The most common image quality aspects that degrade the quality of the 3D models as well possible ways of eliminating these are also discussed. Per patient, a single diagnostic multiphase MRI scan with hepatospecific contrast agent was used for automated segmentation of liver contour, arterial, portal, and venous anatomy, and the biliary tree. Subsequently, lesions were delineated manually. The resulting interactive 3D model could be accessed during surgery on a sterile covered tablet. Up to now, such models have been used in 335 surgical procedures. Their use simplified the surgical treatment of patients with a high number of liver metastases and contributed to the localization of vanished lesions in cases of a radiological complete response to neoadjuvant treatment. They facilitated perioperative verification of the relationship of tumors and the surrounding vascular and biliary anatomy, and eased decision-making before and during surgery.

Influence of preoperative femoral orientation on radiographic measures of femoral head height in total hip replacement

BACKGROUND

In total hip arthroplasty the surgeon aims to restore the biomechanics of the joint. Femoral height has the greatest influence on restoring limb length and contributes equally to the restoration of femoral head centre. On X-ray, the level of femoral neck resection is most often referenced off the upper border of lesser trochanter. Less frequently, femoral head centre is referenced from the tip of the greater trochanter. The error in measurement of femoral height resulting from unknown femoral rotation is crucially important and can result in inappropriate surgical planning for implant selection and placement. It is unknown which reference produces lower error.

METHODS

A sample of femoral shapes was generated using a femoral statistical shape model. These were placed in a range of orientations in terms of external rotation and flexion, at intervals of 10°. Simulated X-rays were then produced and the distances from the tip of either greater or lesser trochanter to femoral head centre were measured.

FINDINGS

Although using greater trochanter as a reference demonstrated greater errors at the extremes, both techniques resulted in errors of 7-8 mm with 20° of both femoral external rotation and flexion.

INTERPRETATION

Moderate degrees of femoral external rotation combined with flexion can result in unsatisfactory errors when templating limb length. There should be greater focus and an agreed definition for femoral height. There is a clinical need for a method with a lower error in determining true femoral height and the level of neck resection.

A virtual reality-based data analysis for optimizing freehand external ventricular drain insertion

PURPOSE

This work exploits virtual reality technique to analyse and optimize the preoperative planning of freehand external ventricular drain (EVD) insertion. Based on the three-dimensional (3D) virtual brain models, neurosurgeons can directly observe the anatomical landmarks and complete the simulated EVD insertion. Simulation data is used to optimize preoperative planning parameters to ensure the surgical performance.

METHODS

We used the computed tomography (CT) scans to construct the 3D virtual brain models. A group of EVD insertions were simulated by inserting virtual catheters at different entry points. The key parameters including the location of entry point, the catheter orientation, the catheter tip position on lateral ventricles, and the insertion depth were recorded. A data analysis method was then applied to optimize these parameters, resulting in the optimal parameters for the EVD insertion.

RESULTS

When the lateral distance of entry point ranged from 2.5 to 3 cm, the success rate of 204 cases was 97.79%, which was higher than that of the classic method (59.52%). The optimal insertion angle towards the sagittal plane ranged from 10.46° to 12.73°. To prevent penetrating the lateral ventricles, the insertion depth was optimized to be 3.28 to 4.58 cm.

CONCLUSIONS

The proposed data analysis method is helpful to optimize the key parameters of the preoperative planning, and provides useful references for neurosurgeons to perform the freehand EVD insertion. The EVD insertion experiments on 3D printing model had a success rate of 93.75%, which verified the effectiveness of the data analysis.

Immersive 3D virtual reality imaging in planning minimally invasive and complex adult cardiac surgery

Aims

Increased complexity in cardiac surgery over the last decades necessitates more precise preoperative planning to minimize operating time, to limit the risk of complications during surgery and to aim for the best possible patient outcome. Novel, more realistic, and more immersive techniques, such as three-dimensional (3D) virtual reality (VR) could potentially contribute to the preoperative planning phase. This study shows our initial experience on the implementation of immersive VR technology as a complementary research-based imaging tool for preoperative planning in cardiothoracic surgery. In addition, essentials to set up and implement a VR platform are described.

Methods

Six patients who underwent cardiac surgery at the Erasmus Medical Center, Rotterdam, The Netherlands, between March 2020 and August 2020, were included, based on request by the surgeon and availability of computed tomography images. After 3D VR rendering and 3D segmentation of specific structures, the reconstruction was analysed via a head mount display. All participating surgeons (n = 5) filled out a questionnaire to evaluate the use of VR as preoperative planning tool for surgery.

Conclusion

Our study demonstrates that immersive 3D VR visualization of anatomy might be beneficial as a supplementary preoperative planning tool for cardiothoracic surgery, and further research on this topic may be considered to implement this innovative tool in daily clinical practice.

Lay summary

Over the past decades, surgery on the heart and vessels is becoming more and more complex, necessitating more precise and accurate preoperative planning. Nowadays, operative planning is feasible on flat, two-dimensional computer screens, however, requiring a lot of spatial and three-dimensional (3D) thinking of the surgeon. Since immersive 3D virtual reality (VR) is an upcoming imaging technique with promising results in other fields of surgery, we aimed in this study to explore the additional value of this technique in heart surgery. Our surgeons planned six different heart operations by visualizing computed tomography scans with a dedicated VR headset, enabling them to visualize the patient's anatomy in an immersive and 3D environment. The outcomes of this preliminary study are positive, with a much more reality-like simulation for the surgeon. In such, VR could potentially be beneficial as a preoperative planning tool for complex heart surgery.