3D navigated implantation of the glenoid component in reversed shoulder arthroplasty. Feasibility and results in an anatomic study

Metaverse, virtual reality and augmented reality in total shoulder arthroplasty: a systematic review

PURPOSE

This systematic review aims to provide an overview of the current knowledge on the role of the metaverse, augmented reality, and virtual reality in reverse shoulder arthroplasty.

METHODS

A systematic review was performed using the PRISMA guidelines. A comprehensive review of the applications of the metaverse, augmented reality, and virtual reality in in-vivo intraoperative navigation, in the training of orthopedic residents, and in the latest innovations proposed in ex-vivo studies was conducted.

RESULTS

A total of 22 articles were included in the review. Data on navigated shoulder arthroplasty was extracted from 14 articles: seven hundred ninety-three patients treated with intraoperative navigated rTSA or aTSA were included. Also, three randomized control trials (RCTs) reported outcomes on a total of fifty-three orthopedics surgical residents and doctors receiving VR-based training for rTSA, which were also included in the review. Three studies reporting the latest VR and AR-based rTSA applications and two proof of concept studies were also included in the review.

CONCLUSIONS

The metaverse, augmented reality, and virtual reality present immense potential for the future of orthopedic surgery. As these technologies advance, it is crucial to conduct additional research, foster development, and seamlessly integrate them into surgical education to fully harness their capabilities and transform the field. This evolution promises enhanced accuracy, expanded training opportunities, and improved surgical planning capabilities.

Validation of mixed-reality surgical navigation for glenoid axis pin placement in shoulder arthroplasty using a cadaveric model

BACKGROUND

Mixed reality may offer an alternative for computer-assisted navigation in shoulder arthroplasty. The purpose of this study was to determine the accuracy and precision of mixed-reality guidance for the placement of the glenoid axis pin in cadaver specimens. This step is essential for accurate glenoid placement in total shoulder arthroplasty.

METHODS

Fourteen cadaveric shoulders underwent simulated shoulder replacement surgery by 7 experienced shoulder surgeons. The surgeons exposed the cadavers through a deltopectoral approach and then used mixed-reality surgical navigation to insert a guide pin in a preplanned position and trajectory in the glenoid. The mixed-reality system used the Microsoft Hololens 2 headset, navigation software, dedicated instruments with fiducial marker cubes, and a securing pin. Computed tomography scans obtained before and after the procedure were used to plan the surgeries and determine the difference between the planned and executed values for the entry point, version, and inclination. One specimen had to be discarded from the analysis because the guide pin was removed accidentally before obtaining the postprocedure computed tomography scan.

RESULTS

Regarding the navigated entry point on the glenoid, the mean difference between planned and executed values was 1.7 ± 0.8 mm; this difference was 1.2 ± 0.6 mm in the superior-inferior direction and 0.9 ± 0.8 mm in the anterior-posterior direction. The maximum deviation from the entry point for all 13 specimens analyzed was 3.1 mm. Regarding version, the mean difference between planned and executed version values was 1.6° ± 1.2°, with a maximum deviation in version for all 13 specimens of 4.1°. Regarding inclination, the mean angular difference was 1.7° ± 1.5°, with a maximum deviation in inclination of 5°.

CONCLUSIONS

The mixed-reality navigation system used in this study allowed surgeons to insert the glenoid guide pin on average within 2 mm from the planned entry point and within 2° of version and inclination. The navigated values did not exceed 3 mm or 5°, respectively, for any of the specimens analyzed. This approach may help surgeons more accurately place the definitive glenoid component.

Mixed-reality improves execution of templated glenoid component positioning in shoulder arthroplasty: a CT imaging analysis

INTRODUCTION

Glenoid placement is critical for successful outcomes in total shoulder arthroplasty (TSA). Preoperative templating with three-dimensional imaging has improved implant positioning, but deviations from the planned inclination and version still occur. Mixed-Reality (MR) is a novel technology that allows surgeons intra-operative access to three-dimensional imaging and templates, capable of overlaying the surgical field to help guide component positioning. The purpose of this study was to compare the execution of preoperative templates using MR vs.standard instruments (SIs).

METHODS

Retrospective review of 97 total shoulder arthroplasties (18 anatomic, 79 reverse) from a single high-volume shoulder surgeon between January 2021 and February 2023, including only primary diagnoses of osteoarthritis, rotator cuff arthropathy, or a massive irreparable rotator cuff tear. To be included, patients needed a templated preoperative plan and then a postoperative computed tomography scan. Allocation to MR vs. SI was based on availability of the MR headset, industry technical personnel, and the templated preoperative plan loaded into the software, but preoperative or intraoperative patient factors did not contribute to the allocation decision. Postoperative inclination and version were measured by two independent, blinded physicians and compared to the preoperative template. From these measurements, we calculated the mean difference, standard deviation (SD), and variance to compare MR and SI.

RESULTS

Comparing 25 MR to 72 SI cases, MR significantly improved both inclination (P < .001) and version (P < .001). Specifically, MR improved the mean difference from preoperative templates (by 1.9° inclination, 2.4° version), narrowed the SD (by 1.7° inclination, 1.8° version), and decreased the variance (11.7-3.0 inclination, 14.9-4.3 version). A scatterplot of the data demonstrates a concentration of MR cases within 5° of plan relative to SI cases typically within 10° of plan. There was no difference in operative time.

CONCLUSION

MR improved the accuracy and precision of glenoid positioning. Although it is unlikely that 2° makes a detectable clinical difference, our results demonstrate the potential ability for technology like MR to narrow the bell curve and decrease the outliers in glenoid placement. This will be particularly relevant as MR and other similar technologies continue to evolve into more effective methods in guiding surgical execution.

Short- to medium-term outcomes and future direction of reverse shoulder arthroplasty: Current concepts

Reverse shoulder arthroplasty is typically indicated for patients with severe shoulder osteoarthritis, rotator cuff tear arthropathy, or proximal humerus fractures that have failed to heal properly. The primary goal of reverse shoulder arthroplasty is to improve shoulder function and reduce pain, while also restoring the ability to perform daily activities. There is a growing body of evidence supporting the effectiveness of reverse shoulder arthroplasty in improving shoulder function and reducing pain in patients with severe shoulder osteoarthritis or rotator cuff tear arthropathy. Reverse shoulder arthroplasty is associated with significant improvements in shoulder function and pain reduction compared to non-surgical treatments. This paper aims to summarize current knowledge, practices and present a summary of the long-term effects of reverse shoulder arthroplasty (RSA) on patient outcomes, including how these outcomes are defined and what measures are typically used to assess them. It will also cover newer definitions of outcomes for RSA that have been developed in recent years in order to better understand the long-term effects of the procedure on patient-reported outcomes and functional ability, as well as information on revision surgery and implant survivorship, and the future of RSA (3D-navigation, patient-specific instrumentation, robotics and artificial intelligence) and its effects on outcomes.

The Value of Computer-Assisted Navigation for Glenoid Baseplate Implantation in Reverse Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Glenoid baseplate malpositioning during reverse total shoulder arthroplasty can contribute to perimeter impingement, dislocation, and loosening. Despite advances in preoperative planning, conventional instrumentation may lead to considerable inaccuracy in implant positioning unless patient-specific guides are used. Optical navigation has the potential to improve accuracy and precision when implanting a reverse shoulder arthroplasty baseplate. This systematic review aimed to analyze the most recent evidence on the accuracy and precision of glenoid baseplate positioning using intraoperative navigation and its potential impact on component selection and surgical time.

METHODS

We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The PubMed, Scopus, and EMBASE databases were queried in July 2022 to identify all studies that compared navigation vs. conventional instrumentation for reverse shoulder arthroplasty. Data of deviation from the planned baseplate version and inclination, the use of standard or augmented glenoid components, and surgical time were extracted. Quantitative analysis from the included publications was performed using the inverse-variance approach and Mantel-Haenszel method.

RESULTS

Of the 2,048 records identified in the initial query, only 10 articles met the inclusion and exclusion criteria, comprising 667 shoulders that underwent reverse total shoulder arthroplasty. The pooled mean difference (MD) of the deviation from the planned baseplate position for the clinical studies was -0.44 (95% confidence interval [CI], -3.26; p = 0.76; I2 = 36%) for version and -8.75 (95% CI, -16.83 to -0.68; p = 0.02; I2 = 83%) for inclination, both in favor of navigation. The odds ratio of selecting an augmented glenoid component after preoperative planning and navigation-assisted surgery was 8.09 (95% CI, 3.82-17.14; p < 0.00001; I2 = 60%). The average surgical time was 12 minutes longer in the navigation group (MD 12.46, 95% CI, 5.20-19.72; p = 0.0008; I2 = 71%).

CONCLUSIONS

Preoperative planning integrated with computer-assisted navigation surgery seems to increase the accuracy and precision of glenoid baseplate inclination compared with the preoperatively planned placement during reverse total shoulder arthroplasty. The surgical time and proportion of augmented glenoid components significantly increase when using navigation. However, the clinical impact of these findings on improving prosthesis longevity, complications, and patient functional outcomes is still unknown.

LEVEL OF EVIDENCE

Level III, systematic review and meta-analysis. See Instructions for Authors for a complete description of levels of evidence.

High intraoperative accuracy and low complication rate of computer-assisted navigation of the glenoid in total shoulder arthroplasty

BACKGROUND

Preoperative planning software with intraoperative guidance technology is increasingly being used to manage complex glenoid deformity in anatomic total shoulder arthroplasty (TSA) and reverse TSA. The aim of this study was to review the intraoperative efficacy and complications of computer-assisted navigation (CAN) surgery for the treatment of glenoid deformity in TSA.

METHODS

We performed a retrospective review of all TSAs implanted using a single computer navigation shoulder system. All patients underwent preoperative planning with computed tomography-based preoperative planning software. The starting point on the glenoid and the final version and inclination of the central post (cage) of the glenoid component were reviewed on the intraoperative navigation guidance report and compared with these parameters on the preoperative plan for each patient. The intraoperative accuracy of CAN for glenoid positioning was determined by the deviation of the starting point and final position of the central cage drill in the glenoid compared with the preoperative plan. Data regarding intraoperative complications and the number of times the navigation system was abandoned intraoperatively were collected.

RESULTS

A total of 16,723 anatomic TSAs and reverse TSAs performed worldwide with the aforementioned navigation system were included in this review. In 16,368 cases (98%), every step of the navigation procedure was completed without abandoning use of the system intraoperatively. There was minimal deviation in the intraoperative execution of the preoperative plan with respect to version (0.6° ± 1.96°), inclination (0.2° ± 2.04°), and the starting point on the glenoid face (1.90 ± 1.2 mm). In this cohort, 9 coracoid fractures (0.05%) were reported.

CONCLUSION AND DISCUSSION

This study demonstrates the safety and efficacy of CAN for glenoid implantation in TSA. Future studies should focus on assessing the impact of CAN on the longevity and survival of glenoid components and improving the cost-effectiveness of this technology.

Augmented reality through head-mounted display for navigation of baseplate component placement in reverse total shoulder arthroplasty: a cadaveric study

BACKGROUND

To achieve an optimal clinical outcome in reverse total shoulder arthroplasty (RSA), accurate placement of the components is essential. The recently introduced navigation technology of augmented reality (AR) through head-mounted displays (HMD) offers a promising new approach to visualize the anatomy and navigate component positioning in various orthopedic surgeries. We hypothesized that AR through HMD is feasible, reliable, and accurate for guidewire placement in RSA baseplate positioning.

METHODS

Twelve human cadaver shoulders were scanned with computed tomography (CT) and RSA baseplate positioning was 3-D planned using dedicated software. The shoulders were prepared through a deltopectoral approach and an augmented reality hologram was superimposed using the HMD Microsoft HoloLense. The central guidewire was then navigated through the HMD to achieve the planned entry point and trajectory. Postoperatively, the shoulders were CT-scanned a second time and the deviation from the planning was calculated.

RESULTS

The mean deviation of the entry point was 3.5 mm  ± 1.7 mm (95% CI 2.4 mm; 4.6 mm). The mean deviation of the planned trajectory was 3.8°  ± 1.7° (95% CI 2.6°; 4.9°).

CONCLUSION

Augmented reality seems feasible and reliable for baseplate guidewire positioning in reverse total shoulder arthroplasty. The achieved values were accurate.

A Systematic Review of the Utility of Intraoperative Navigation During Total Shoulder Arthroplasty

Total shoulder arthroplasty (TSA) has been demonstrated to successfully recover function to shoulders impaired by arthrosis and rotator cuff insufficiency. Long-term survival depends on the correct positioning of glenoid components and secure bone fixation. Computed tomography (CT)-based intraoperative navigation has proven to be an effective technique for successful TSA procedures. This paper presents a review of CT-based intraoperative navigation considering its advantages and disadvantages. The crucial factors that contribute to the success of this technique are glenoid component positioning, operative duration, and screw selection, which are detailed in this review.

Navegação em cirurgia de artroplastia de ombro

The indication of shoulder arthroplasties has increased progressively. Accurate positioning of the components may have significant implications for clinical results. The navigation used to aid in the performance of anatomical and reverse total arthroplasties has provided greater precision in implant placement, especially on the glenoid. The development of the technique, material, and prosthesis design have shown encouraging results and led to a trend toward its expansion. In this way, we estimate a higher survival of the arthroplasties resulting from lower rates of dislocation and early loosening. We aim to describe the current technique and to present the results of the literature with navigation. However, comparative clinical studies with long term follow-up are necessary to prove the efficacy in the final results of total shoulder arthroplasties.

Three dimensional patient-specific guides for guide pin positioning in reverse shoulder arthroplasty: An experimental study on different glenoid types

INTRODUCTION

Incorrect positioning is one of the main factors for glenoid component loosening in reverse shoulder arthroplasty and component placement can be challenging. This study aimed to assess whether Patient-Specific Instrumentation (PSI) provides better guide pin positioning accuracy and is superior to standard guided and freehand instrumentation methods in cases of glenoid bone deformity.

MATERIALS AND METHODS

Based on the Walch classification, five different scapula types were acquired by computed tomography (CT). For each type, two different surgeons placed a guide pin into the scapula using three different methods: freehand method, conventional non-patient-specific guide, and PSI guide. Each method was repeated five times by both surgeons. In these experiments, a total of 150 samples of scapula models were used (5 × 2 × 3 × 5 = 150). Post-operative CT scans of the samples with the guide pin were digitally assessed and the accuracy of the pin placement was determined by comparison to the preoperative planning on a three-dimensional (3D) model.

RESULTS

The PSI method showed accuracies to the preoperative plan of 2.68 (SD 2.10) degrees for version angle (p < .05), 2.59 (SD 2.68) degrees for inclination angle (p < .05), and 1.55 (SD 1.26) mm for entry point offset (p < .05). The mean and standard deviation errors compared to planned values of version angle, inclination angle, and entry point offset were statistically significant for the PSI method for the type C defected glenoid and non-arthritic glenoid.

CONCLUSION

Using the PSI guide created by an image processing software tool for guide pin positioning showed advantages in glenoid component positioning over other methods, for defected and intact glenoid types, but correlation with clinical outcomes should be examined.

A comparison of patient-specific instrumentation to navigation for conducting humeral head osteotomies during shoulder arthroplasty

Background

The humeral head osteotomy during shoulder arthroplasty influences humeral component height, version and possibly neck-shaft angle. These parameters all potentially influence outcomes of anatomic and reverse shoulder replacement to a variable degree. Patient-specific guides and navigation have been studied and utilized clinically for glenoid component placement. Little, however, has been done to evaluate these techniques for humeral head osteotomies. The purpose of this study, therefore, was to evaluate the use of patient-specific guides and surgical navigation for executing a planned humeral head osteotomy.

Methods

The DICOM images of 10 shoulder computed tomography scans (5 normal and 5 osteoarthritic) were used to print 3D polylactic models of the humerus. Each model was duplicated, such that there were 2 identical groups of 10 models. After preoperative planning of a humeral head osteotomy, Group 1 underwent osteotomy via a patient-specific guide, while group 2 underwent a real time navigated osteotomy with an optically tracked sagittal saw. The cut height (millimeters), version (degrees) and neck-shaft angle (degrees) were recorded and statistically compared between groups.

Results

There were no statistically significant differences between patient-specific guides and navigation for osteotomy cut height (P = .45) and humeral version (P = .059). Navigation, however, resulted in significantly less neck-shaft angle error than the patient specific guides (P = .023). Subgroup analysis of the osteoarthritic cases showed statistical significance for navigation resulting in less version error than the patient specific guides (P = .048).

Conclusion

No significant differences were found between patient specific guides and navigation for recreation of the preoperatively planned humeral head cut height and version. Neck-shaft angle, however, had significantly less deviation from the preoperative plan when conducted with navigation.

Computer-Assisted Orthopedic and Trauma Surgery

BACKGROUND

There are many ways in which computer-assisted orthopedic and trauma surgery (CAOS) procedures can help surgeons to plan and execute an intervention.

METHODS

This study is based on data derived from a selective search of the literature in the PubMed database, supported by a Google Scholar search.

RESULTS

For most applications the evidence is weak. In no sector did the use of computer-assisted surgery yield any relevant clinical or functional improvement. In trauma surgery, 3D-navigated sacroiliac screw fixation has become clinically established for the treatment of pelvic fractures. One randomized controlled trial showed a reduction in the rate of screw misplacement: 0% with 3D navigation versus 20.4% with the conventional procedure und 16.6% with 2D navigation. Moreover, navigation-assisted pedicle screw stabilization lowers the misplacement rate. In joint replacements, the long-term results showed no difference in respect of clinical/functional scores, the time for which the implant remained in place, or aseptic loosening.

CONCLUSION

Computer-assisted procedures can improve the precision of certain surgical interventions. Particularly in joint replacement and spinal surgery, the research is moving away from navigation in the direction of robotic procedures. Future studies should place greater emphasis on clinical and functional results.

Computer navigation leads to more accurate glenoid targeting during total shoulder arthroplasty compared with 3-dimensional preoperative planning alone

BACKGROUND

Commercially available preoperative planning software is now widely available for shoulder arthroplasty. However, without the use of patient-specific guides or intraoperative visual guidance, surgeons have little in vivo feedback to ensure proper execution of the preoperative plan. The purpose of this study was to assess surgeons' ability to implement a preoperative plan in vivo during shoulder arthroplasty.

METHODS

Fifty primary shoulder arthroplasties from a single institution were retrospectively reviewed. All surgical procedures were planned using a commercially available software package with both multiplanar 2-dimensional computed tomography and a 3-dimensional implant overlay. Following registration of intraoperative visual navigation trackers, the surgeons (1 attending and 1 fellow) were blinded to the computer navigation screen and attempted to implement the plan by simulating placement of a central-axis guide pin. Malposition was assessed (>4 mm of displacement or >10° error in version or inclination). Data were then blinded, measured, and evaluated.

RESULTS

Mean displacement from the planned starting point was 3.2 ± 2.0 mm. The mean error in version was 6.4° ± 5.6°, and the mean error in inclination was 6.6° ± 4.9°. Malposition was observed in 48% of cases after preoperative planning. Malposition errors were more commonly made by fellow trainees vs. attending surgeons (58% vs. 38%, P = .047).

CONCLUSIONS

Despite preoperative planning, surgeons of various training levels were unable to reproducibly replicate the planned component position consistently. Following completion of fellowship training, significantly less malposition resulted. Even in expert hands, the orientation of the glenoid component would have been malpositioned in 38% of cases. This study further supports the benefit of guided surgery for accurate placement of glenoid components, regardless of fellowship training.

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty

BACKGROUND

Inaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA.

METHODS

This retrospective case-control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded.

RESULTS

Compared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation.

CONCLUSION

O-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.

Computer navigation re-creates planned glenoid placement and reduces correction variability in total shoulder arthroplasty: an in vivo case-control study

BACKGROUND

Accurate glenoid component placement is important to prevent glenoid component failure in total shoulder arthroplasty (TSA). Navigation may reduce the variability of glenoid component version and inclination; therefore, the aims of this study were to determine, in patients undergoing TSA, whether computer navigation improved the ability to achieve neutral postoperative version and inclination, as well as achieve the individualized preoperative plan.

METHODS

Patients undergoing TSA using navigation (computer-assisted surgery [CAS], n = 33) or the conventional technique (n = 27) from January 2014 to July 2017 were recruited and compared. Preoperative and postoperative version and inclination, as well as postoperative inferior overhang, were measured using computed tomography scans.

RESULTS

The CAS group had more than twice as many augmented glenoid components as the conventional group (45.5% vs. 19.2%). CAS significantly reduced the between-patient variability in postoperative version and led to a greater proportion of components positioned in "neutral" alignment for both inclination and version (P < .015). The incidence of neutral inclination or version postoperatively was significantly higher in the CAS group, and the glenoid was implanted within 5° of the surgical plan in more than 70% of cases, with more than 40% displaying no detectable difference.

CONCLUSION

An integrated system of 3-dimensional surgical planning, augmented glenoid components, and intraoperative navigation may reduce the risk of glenoid placement outside of a neutral position in patients undergoing TSA compared with conventional methods. This study demonstrated the capacity for CAS to replicate the surgical plan in a majority of cases.

Glenoid component positioning and guidance techniques in anatomic and reverse total shoulder arthroplasty: A systematic review and meta-analysis

BACKGROUND

Positioning of the glenoid component is one of the most challenging steps in shoulder arthroplasty, and prosthesis longevity as well as functional outcomes is considered highly dependent on accurate positioning. This review considers the evidence supporting surgical navigation and patient-specific instruments for glenoid implant positioning in anatomic and reverse total shoulder arthroplasty.

METHODS

A systematic literature search was performed for studies assessing glenoid implant positioning accuracy as measured by cross-sectional imaging on live subjects or cadaver models. Meta-analysis of controlled studies was performed to estimate the primary effects of navigation and patient-specific instruments on glenoid implant positioning error. Meta-analysis of absolute positioning outcomes was also performed for each group incorporating data from controlled and uncontrolled studies.

RESULTS

Nine studies, four controlled and five uncontrolled, with 258 total subjects were included in the analysis. Meta-analysis of controlled studies supported that both navigation and patient-specific instruments had a moderate statistically significant effect on improving glenoid implant positioning outcomes. Meta-analysis of absolute positioning outcomes demonstrates glenoid implant positioning with standard instrumentation results in a high rate of malposition.

DISCUSSION

Navigation and patient-specific instruments improve glenoid positioning outcomes. Whether the improvement in positioning outcomes achieved translate to better clinical outcomes is unknown.

Real-time intraoperative 3D image intensifier-based navigation in reversed shoulder arthroplasty- analyses of image quality

Background

Due to the high anatomical variability and limited visualization of the scapula, optimal screw placement for baseplate anchorage in reversed total shoulder arthroplasty (rTSA) is challenging. Image quality plays a key role regarding the decision of an appropriate implant position. However, these data a currently missing for rTSA and were investigated in the present study. Furthermore, the rate of required K-wire changes for the central peg as well as post-implantation inclination and version were assessed.

Methods

In ten consecutive patients (8 female, 86 years, range 74–94) with proximal humeral fracture and indication for rTSA, an intraoperative 3D-scan of the shoulder with a 3D image intensifier (Ziehm Vision FD Vario 3D© [Ziehm Imaging GmbH, Nürnberg, Germany]) was performed after resection of the humeral head. Using the Vectorvision© Software (Brainlab AG, Feldkirchen, Germany), the virtual anatomy was compared to the visible anatomical landmarks. After implantation of the baseplate, a 3D scan was performed. All 3D scans included multiplanar reconstruction (MPR) and the cinemode to examine screw and baseplate placement. The rate of required K-wire changes was assessed. The intraoperative 3D image quality (modified visual analogue scale [VAS] and point system) was assessed before and after implantation of the glenoid component. Inclination and version were determined in post-implantation scans.

Results

The virtually presented anatomical landmarks always correlated to the anatomical visible points indicating an good virtual accuracy. The central K-wire position was corrected in three cases due to a deviation from the face plane technique position. The VAS was higher for the pre-implantation MPR (6.7, range 5–8) compared to the post-implantation acquired MPR (5.1, range 4–6; p = 0.0002). The point system showed a reduced quality in all subcategories, especially regarding the grading of the articular surfaces. The preoperative (7.9, range 6–9) and post-implantation (7.9, range 6–9) cinemode displayed no significant differences (p = 0.6).

Conclusion

The present study underlines the need for the improvement of 3D image intensifiers algorithms to reduce artifact associated impaired image quality to enhance the benefit of real-time intraoperative 3D scans and navigation.

Relationship of Intraoperative Anatomical Landmarks, the Scapular Plane and the Perpendicular Plane with Glenoid for Central Guide Insertion during Shoulder Arthroplasty

Background

This study was undertaken to evaluate the positional relationship between planes of the glenoid component (the scapular plane and the perpendicular plane to the glenoid) and its surrounding structures.

Methods

Computed tomography (CT) images of both shoulders of 100 patients were evaluated using the 3-dimensional CT reconstruction program (Aquarius^®; TeraRecon). We determined the most lateral scapular bony structure of the scapular plane and measured the shortest distance between the anterolateral corner of the acromion and the scapular plane. The distance between the scapular plane and the midpoint of the line connecting the posterolateral corner of acromion and the anterior tip of the coracoid process (fulcrum axis) was also evaluated. The perpendicular plane was then adjusted to the glenoid and the same values were re-assessed.

Results

The acromion was the most lateral scapular structure of scapular plane and perpendicular plane to the glenoid. The average distance from the anterolateral corner of the acromion to the scapular plane was 10.44 ± 5.11 mm, and to the plane perpendicular to the glenoid was 9.55 ± 5.13 mm. The midpoint of fulcrum axis was positioned towards the acromion and was measured at 3.90 ± 3.21 mm from the scapular plane and at 3.84 ± 3.17 mm from the perpendicular plane to the glenoid.

Conclusions

Our data indicates that the relationship between the perpendicular plane to the glenoid plane and its surrounding structures is reliable and can be used as guidelines during glenoid component insertion (level of evidence: Level IV, case series, treatment study).

Improved accuracy of K-wire positioning into the glenoid vault by intraoperative 3D image intensifier-based navigation for the glenoid component in shoulder arthroplasty

INTRODUCTION

This article aimed to show that navigation, based on an intraoperative mobile 3D image intensifier, can improve the accuracy of central K-wire placement into the glenoid vault for glenoid component.

HYPOTHESIS

The navigated k-wire placement is more accurate and shows a smaller deviation angle to the standard centerline compared to the classical "free hand technic".

METHODS

In 34 fresh frozen sheep scapulae, 17 K-wire placements using the navigation (group 1) were compared with 17 using standard "face plane technique" (group 2). The relation to glenoid standard and alternative centerlines (CL) and the position within the glenoid vault were analyzed.

RESULTS

In groups 1 and 2 the angle between the K-wire and standard CL was 2.2° and 4.7°, respectively (P=0.01). The angle between the K-wire and alternative CL was 14.4° for group 1 and 17.2° for group 2 (P=0.02). More navigated K-wire positions were identified within a 5mm corridor along the glenoid vault CL (52 vs. 39; P=0.004).

DISCUSSION

Intraoperative 3D image intensifier-based navigation was more accurate and precise than standard K-wire placement.

TYPE OF STUDY AND LEVEL OF PROOF

Basic science study, evidence level III.

Planning software and patient-specific instruments in shoulder arthroplasty

Computer planning software and patient-specific instrumentation have been investigated in multiple subspecialties of orthopedics with mixed results. Shoulder arthroplasty has evolved over the last decade with improvements in implant design and surgical instrumentation. Despite these advances, glenoid positioning in shoulder arthroplasty continues to be a difficult problem. Recent advances in three-dimensional imaging techniques and the use of computer planning software may potentially address some of the common difficulties encountered by surgeons. The addition of patient-specific instrumentation and guides provide an option for patients with significant glenoid deformity that may allow improved accuracy of glenoid component implantation compared to using standard instrumentation. Studies have reported improved positioning of the glenoid component in both anatomic and reverse total shoulder arthroplasty with patient-specific instrumentation and guides. More research is needed to determine whether these improvements lead to better patient-reported outcomes or implant survival. In addition, further studies will be needed to address whether this technology is cost effective for large-scale implementation in the orthopedic community.

Patient-specific targeting guides compared with traditional instrumentation for glenoid component placement in shoulder arthroplasty: a multi-surgeon study in 70 arthritic cadaver specimens

HYPOTHESIS AND BACKGROUND

The purpose of this study was to compare the accuracy of patient-specific guides for total shoulder arthroplasty (TSA) with traditional instrumentation in arthritic cadaver shoulders. We hypothesized that the patient-specific guides would place components more accurately than standard instrumentation.

MATERIALS AND METHODS

Seventy cadaver shoulders with radiographically confirmed arthritis were randomized in equal groups to 5 surgeons of varying experience levels who were not involved in development of the patient-specific guidance system. Specimens were then randomized to patient-specific guides based off of computed tomography scanning, standard instrumentation, and anatomic TSA or reverse TSA. Variances in version or inclination of more than 10° and more than 4 mm in starting point were considered indications of significant component malposition.

RESULTS

TSA glenoid components placed with patient-specific guides averaged 5° of deviation from the intended position in version and 3° in inclination; those with standard instrumentation averaged 8° of deviation in version and 7° in inclination. These differences were significant for version (P = .04) and inclination (P = .01). Multivariate analysis of variance to compare the overall accuracy for the entire cohort (TSA and reverse TSA) revealed patient-specific guides to be significantly more accurate (P = .01) for the combined vectors of version and inclination. Patient-specific guides also had fewer instances of significant component malposition than standard instrumentation did.

CONCLUSION

Patient-specific targeting guides were more accurate than traditional instrumentation and had fewer instances of component malposition for glenoid component placement in this multi-surgeon cadaver study of arthritic shoulders. Long-term clinical studies are needed to determine if these improvements produce improved functional outcomes.

"Advances in the surgical management of bone tumors"

Bone tumor surgery is extremely challenging, particularly when tumors are located in tightly confined anatomical areas and abutting critical organs and neurovascular structures. Tumor resection requires good cutting accuracy to ensure safety, to achieve negative margins, and to preserve critical structures when possible. The purpose of this paper was to review the literature on the surgical advances for bone tumor surgery published within the last year. The majority of literature identified focused on computer-assisted surgical approaches. There is increasing evidence that 3D navigation plays an important role in the resection of bone tumors. Reconstruction materials that encourage healing and prevent infections are also in development. Optimal care includes execution of a well-developed pre-operative plan using a multidisciplinary approach led by the orthopaedic oncologist.

Benefit of intraoperative navigation on glenoid component positioning during total shoulder arthroplasty

INTRODUCTION

The objective of this study was to review and synthesize the current best evidence for the use of intraoperative navigation in the implantation of glenoid components in total shoulder prostheses.

METHODS

We conducted a systematic, online search using PubMed, EMBASE, CCTR, and CINAHL using "Arthroplasty, Replacement"(Mesh) AND (shoulder) AND (navi* OR computer). Data on study design and quality as well as accuracy of positioning and complications were extracted independently and in duplicate. After assessment of study heterogeneity, DerSimonian-Laird random effect models were used to pool data from the individual studies.

RESULTS

The systematic search revealed 359 manuscripts in total. After exclusion of duplicates and irrelevant publications, 6 groups of 247 shoulders from 5 studies were included. The pooled weighted mean difference for deviation from neutral version was -6.4° (95 %CI -7.9 to -5.3) in favor of navigation, which is consistent with a statistically significant difference (p < 0.01). In the navigation group, 2 superior glenoid screws were reported as perforating compared to 5 screws (1 inferior, 4 superior) in the control group. There was no difference in tilt at a WMD of 2.7 (95 %CI -1.4 to 6.8, p = 0.192).

CONCLUSIONS

Navigation allows for significantly more accurate glenoid version, but the clinical meaningfulness of the absolute improvement over standard techniques is questionable. However, navigation is a valuable teaching tool that might prove very beneficial not for the patient at hand, but for those treated by the operating surgeon in the future.

LEVEL OF EVIDENCE

Level II-meta-analysis of non-homogenous controlled trials.

Avoiding superior tilt in reverse shoulder arthroplasty: a review of the literature and technical recommendations

Superior tilt of the baseplate component in reverse total shoulder arthroplasty leads to tensile baseplate forces and may be a contributor to early loosening. The risk factors for this implant malposition include inadequate exposure through a superior approach and superior glenoid bone deficiency that obscures the native glenoid tilt. Here we review our preoperative evaluation and surgical management strategies to avoid superior tilt. Adequate exposure with a superior approach can be achieved but requires not just proper surgical technique but also careful patient selection. We propose that the superior approach be considered only for acute proximal humerus fractures or in patients when the following criteria are met: no prior open surgery on the shoulder; more than 30° of passive external rotation at 0° of abduction; no medial humeral osteophytes; and any superior migration must be reducible with a sulcus test during examination under anesthesia. Avoiding superior tilt when there is significant superior glenoid erosion can be accomplished with humeral head autograft, most easily performed through a deltopectoral approach. Preoperative templating is critical to determine proper graft thickness, inclination, reaming depth, and harvest technique.