Placement Of Glenoid Component Research Articles

Augmented Reality Assisted Intraoperative Navigation Increases Precision of Glenoid Inclination in Reverse Shoulder Arthroplasty

BackgroundReverse Total Shoulder Arthroplasty (RTSA) is the standard of care for patients with glenohumeral osteoarthritis and rotator cuff deficiency. Preoperative RTSA planning based on medical images and patient-specific instruments has been established over the last decade. This study aims to determine the effects of using augmented reality assisted intraoperative navigation (ARIN) for baseplate positioning in RTSA compared to preoperative planning. It is hypothesized that ARIN will decrease deviation between preoperative planning and postoperative baseplate positioning. Moreover, ARIN will decrease deviation between the (senior) more (> 50 RTSA/year) and less experienced (junior) surgeon (5-10 RTSA/year). MethodsPreoperative CT scans of sixteen fresh-frozen cadaveric shoulders were obtained. Baseplate placements were planned using a validated software. The data was then converted and uploaded to the augmented reality system (NextAR; Medacta International, Castel San Pietro, Switzerland). Each of the eight RTSAs were implanted by a senior and a junior surgeon, with four RTSAs utilizing ARIN and four without. A postoperative CT scan was performed in all cases. The scanned scapulae were segmented, and the preoperative scan was laid over the postoperative scapula by nearest iterative point cloud analysis. The deviation from the planned entry point and trajectory was calculated regarding the inclination, retroversion, medialization (reaming depth)/lateralization, antero-posterior position and superior/inferior position of the baseplate. Data are reported as mean ± standard deviation (SD) or mean and 95% confidence interval (CI). P values <0.05 were considered statistically significant. ResultsThe use of ARIN yielded a reduction in the absolute difference between planned and obtained inclination from 9° (SD: 4°) to 3° (SD°:2) (p=0.011). Mean difference in planned-obtained inclination between surgeons was 3° in free-hand surgeries (95%CI: -4,10, p=0.578), while this difference reduced to 1° (95%CI: -6, 7, p=0.996) using ARIN. Retroversion, medialization (reaming depth)/lateralization, antero-posterior position and superior/inferior position of the baseplate were not affected by using ARIN. Surgical duration was increased using ARIN for both the senior (10 mins) and junior (18 mins) surgeon. ConclusionsThe implementation of augmented reality assisted intraoperative navigation (ARIN) leads to greater accuracy of glenoid component placement, specifically with respect to inclination. Further studies have to verify if this increased accuracy is clinical important. Furthermore, ARIN allows less experienced surgeons to achieve a similar level of accuracy in component placement comparable to more experienced surgeons. However, the potential advantages of ARIN in RTSA are counterbalanced by an increase in operative time.

Beyond Shoulder Arthroplasty: Applications of 3D Printed Patient-Specific Instrumentation in Shoulder and Elbow Procedures – A Systematic Review.

PurposeAdvancements in 3D printing technology have led to a growing interest on its application in orthopedic surgery. In the context of shoulder and elbow surgery, studies on 3D printing mostly center on surgical guides for the placement of the glenoid component in shoulder arthroplasty, but applications in non-arthroplasty procedures remain unclear. This systematic review aims to evaluate and summarize the literature on the current applications and clinical outcomes of 3D Patient-Specific Instruments (3DPSI) in non-arthroplasty procedures. We expected to find a predominant focus on corrective osteotomies with positive clinical outcomes and minimal complications. MethodsThis systematic review adhered to PRISMA guidelines. Eligibility criteria included original research studies presenting primary data on 3DPSI for shoulder and elbow procedures. Exclusions were applied to studies exclusively reporting clinical data on 3DPSI for glenoid component placement in shoulder arthroplasty. A comprehensive literature search was conducted in PubMed/MEDLINE, Scopus, MedNar, Google Scholar, OAIster, and ProQuest Dissertations & Theses. Extracted data included study characteristics, 3DPSI development details, and clinical outcomes. Risk of bias was assessed using MINORS criteria. ResultsOut of 845 initially identified records, the final analysis included 20 studies. Regarding the application of 3DPSI, 35% of the reports addressed cubitus varus osteotomy correction, 30% focused on clavicle malunion or nonunion, and 15% centered on corrective osteotomies for proximal humerus malunion. Risk of bias assessment using MINORS criteria demonstrated a mean score of 9.11 out of 16 for studies without a comparator group. Results across different pathologies revealed high patient-reported outcomes (PROs), good patient satisfaction, and minimal complications, which are presented. ConclusionIn non-arthroplasty shoulder and elbow procedures, 3D Printed Patient-Specific Instrumentation have been mostly used for corrective osteotomies and demonstrates overall positive outcomes, low complications, and high patient satisfaction. Advancement in existing knowledge requires robust studies with larger cohorts and comparator groups. Level of EvidenceLevel IV. Clinical RelevanceThis study, summarizing existing data on 3D Patient-Specific Instruments (3DPSI) in non-arthroplasty shoulder and elbow procedures, offers guidance for future applications and research in this evolving field of orthopedic surgery.

Glenoid component placement in reverse shoulder arthroplasty assisted with augmented reality through a head-mounted display leads to low deviation between planned and postoperative parameters.

Navigated augmented reality (AR) through a head-mounted display (HMD) may lead to accurate glenoid component placement in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the deviation between planned, intra- and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement assisted by a navigated AR through HMD during RSA. Both shoulders of 6 fresh frozen human cadavers, free from fractures or other bony pathologies, were used. Preoperative computed tomography (CT) scans were used for the 3-dimensional (3D) planning. The glenoid component placement was assisted using a navigated AR system through an HMD in all specimens. Intraoperative inclination, retroversion, depth, and rotation were measured by the system. A postoperative CT scan was performed. The pre- and postoperative 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement. Additionally, a comparison between intra- and postoperative values was calculated. Outliers were defined as >10° inclination, >10° retroversion, >3 mm entry point. The registration algorithm of the scapulae prior to the procedure was correctly completed for all cases. The deviations between planned and postoperative values were 1.0°±0.7° for inclination, 1.8°±1.3° for retroversion, 1.1±0.4 mm for entry point, 0.7±0.6 mm for depth, and 1.7°±1.6° for rotation. The deviation between intra- and postoperative values were 0.9°±0.8° for inclination, 1.2°±1.1° for retroversion, 0.6±0.5 mm for depth, and 0.3°±0.2° for rotation. There were no outliers between planned and postoperative parameters. In this study, the use of a navigated AR system through an HMD for RSA led to low deviation between planned and postoperative values and between intra- and postoperative parameters.

3-dimensionally printed patient-specific glenoid drill guides vs. standard nonspecific instrumentation: a randomized controlled trial comparing the accuracy of glenoid component placement in anatomic total shoulder arthroplasty

Traditional, commercially-sourced patient-specific instrumentation (PSI) systems for shoulder arthroplasty improve glenoid component placement but can involve considerable cost and outsourcing delays. The purpose of this randomized controlled trial was to compare the accuracy of glenoid component positioning in anatomic total shoulder arthroplasty (aTSA) using an in-house, point-of-care, 3-dimensionally (3D) printed patient-specific glenoid drill guide versus standard non-specific instrumentation. This single-center randomized controlled trial included 36 adult patients undergoing primary aTSA. Patients were blinded and randomized 1:1 to either the PSI or the standard aTSA guide groups. The primary endpoint was accuracy of glenoid component placement (version and inclination), which was determined using a metal-suppression CT scan taken between 6 weeks to 1 year postoperatively. Deviation from the preoperative 3D templating plan was calculated for each patient. Blinded postoperative CT measurements were performed by a fellowship-trained shoulder surgeon and a musculoskeletal radiologist. Nineteen patients were randomized to the patient-specific glenoid drill guide group, and 17 were allocated to the standard instrumentation control group. There were no significant differences between the two groups for native version (p = 0.527) or inclination (p = 0.415). The version correction was similar between the two groups (p = 0.551), and the PSI group was significantly more accurate when correcting version than the control group (p = 0.042). The PSI group required a significantly greater inclination correction than the control group (p = 0.002); however, the two groups still had similar accuracy when correcting inclination (p = 0.851). For the PSI group, there was no correlation between accuracy of component placement and native version, native inclination, or Walch classification of glenoid wear (p > 0.05). For the control group, accuracy when correcting version was inversely correlated with native version (p = 0.033), but accuracy was not correlated with native inclination or Walch classification of glenoid wear (p > 0.05). The intraclass correlation coefficient (ICC) was 0.703 and 0.848 when measuring version and inclination accuracy respectively. When compared to standard instrumentation, the use of in-house, 3D-printed, patient-specific glenoid drill guides during aTSA led to more accurate glenoid component version correction and similarly accurate inclination correction. Additional research should examine the influence of proper component position and use of patient-specific instrumentation on clinical outcomes.

Glenoid component placement accuracy in total shoulder arthroplasty with preoperative planning and standard instrumentation is not influenced by supero-inferior glenoid erosion.

Accurate glenoid component placement in total shoulder arthroplasty (TSA) remains challenging even with preoperative planning, especially for variable glenoid erosion patterns in the coronal plane. We retrospectively reviewed 170 primary TSAs in which preoperative planning software was used. After registration of intraoperative bony landmarks, surgeons were blinded to the navigation screen and attempted to implement their plan by simulating placement of a central-axis guide pin: 230 screenshots of simulated guide pin placement were included (aTSA = 66, rTSA = 164). Displacement, error in version and inclination, and overall malposition from the preoperatively-planned target point were stratified by the Favard classification describing superior-inferior glenoid wear: E0 (n = 89); E1 (n = 81); E2 (n = 29); E3(n = 29); E4(n = 2). Malposition was considered > 10° for version/inclination errors or > 4mm displacement from the starting point. Mean displacement error was 3.5 ± 2.7mm (aTSA = 2.7 ± 2.3mm, rTSA = 3.8 ± 2.9mm), version error was 5.7 ± 4.7° (aTSA = 5.8 ± 4.4°, rTSA = 5.7 ± 4.8°), inclination error was 7.1 ± 5.6 (aTSA = 4.8 ± 4.8°, rTSA = 8.1 ± 5.7°), and malposition rate was 53% (aTSA = 38%, rTSA = 59%). When compared by Favard classification, there were no differences in any measure; when stratified by TSA type, version error differed for rTSAs (P = .038), with E1 having the greatest version error (6.9 ± 5.2°) and E3 the least (4.2 ± 3.4°). When comparing glenoids without wear (E0) and glenoids with superior wear (E2 and E3), the only difference was greater version error in glenoids without wear (6.0 ± 4.9° vs. 4.6 ± 3.7°, P = .041). Glenoid malposition did not differ based on coronal glenoid morphology. Although, malposition was relatively high, suggesting surgeons should consider alternate techniques beyond preoperative planning and standard instrumentation in TSA. LEVEL OF EVIDENCEIII: Retrospective Cohort Study.

Image-derived instrumentation vs. conventional instrumentation with 3D planning for glenoid component placement in reverse total shoulder replacements: a randomized controlled trial

Image-derived instrumentation vs. conventional instrumentation with 3D planning for glenoid component placement in reverse total shoulder replacements: a randomized controlled trial

IMAGE-DERIVED INSTRUMENTATION VERSUS CONVENTIONAL INSTRUMENTATION WITH 3D PLANNING FOR GLENOID COMPONENT PLACEMENT IN REVERSE TOTAL SHOULDER ARTHROPLASTY: A RANDOMIZED CONTROLLED TRIAL

Glenoid baseplate positioning for reverse total shoulder replacements (rTSR) is key for stability and longevity. 3D planning and image-derived instrumentation (IDI) are techniques for improving implant placement accuracy. This is a single-blinded randomised controlled trial comparing 3D planning with IDI jigs versus 3D planning with conventional instrumentation.Eligible patients were enrolled and had 3D pre-operative planning. They were randomised to either IDI or conventional instrumentation; then underwent their rTSR. 6 weeks post operatively, a CT scan was performed and blinded assessors measured the accuracy of glenoid baseplate position relative to the pre-operative plan.47 patients were included: 24 with IDI and 23 with conventional instrumentation. The IDI group were more likely to have a guidewire placement within 2mm of the preoperative plan in the superior/inferior plane when compared to the conventional group (p=0.01). The IDI group had a smaller degree of error when the native glenoid retroversion was &gt;10° (p=0.047) when compared to the conventional group. All other parameters (inclination, anterior/posterior plane, glenoids with retroversion &lt;10°) showed no significant difference between the two groups.Both IDI and conventional methods for rTSA placement are very accurate. However, IDI is more accurate for complex glenoid morphology and placement in the superior-inferior plane. Clinically, these two parameters are important and may prevent long term complications of scapular notching or glenoid baseplate loosening.Image-derived instrumentation (IDI) is significantly more accurate in glenoid component placement in the superior/inferior plane compared to conventional instrumentation when using 3D pre-operative planning. Additionally, in complex glenoid morphologies where the native retroversion is &gt;10°, IDI has improved accuracy in glenoid placement compared to conventional instrumentation. IDI is an accurate method for glenoid guidewire and component placement in rTSA.

Implications of navigation system use for glenoid component placement in reverse shoulder arthroplasty

Recently, three-dimensional (3D) planning, patient-specific instruments, and navigation system have been developed to improve the accuracy of baseplate placement in reverse shoulder arthroplasty (RSA). The purpose of this study was to evaluate baseplate placement using the navigation system. Sixty-four shoulders in 63 patients who underwent RSA for rotator cuff tear arthropathy or irreparable rotator cuff tears were enrolled. Conventional RSA was performed in 31 shoulders and navigated RSA using pre-operative planning software was performed in 33 shoulders. The use of augmented baseplates, the version and inclination of the baseplate, and screw length were compared between conventional RSA and navigated RSA. Augmented baseplates were used more frequently in navigated RSA than in conventional RSA (20 vs 9 shoulders, p = 0.014). Baseplate alignment was 1.0° (SD 5.1) of retroversion and 2.4° (SD 6.8) of superior inclination in conventional RSA and 0.2° (SD 1.9) of anteversion and 0.3° (SD 1.7) of superior inclination in navigated RSA. Compared with conventional RSA, precision of baseplate version and inclination were higher in navigated RSA (both p < 0.001). Superior, inferior, and posteroinferior screws were significantly longer in navigated RSA than in conventional RSA (p = 0.021, 0.001 and < 0.001, respectively). Precision of superior and inferior screw lengths was significantly higher in navigated RSA than in conventional RSA (both p = 0.001). Our results suggest that adoption of pre-operative planning software increased augmented baseplate use to minimize the glenoid reaming. The navigation system allows placement of the baseplate accurately, according to the pre-operative plan. Furthermore, the navigation system enables monitoring of screw length and direction in real time.

Glenoid Component Placement Assisted by Augmented Reality Through a Head-Mounted Display During Reverse Shoulder Arthroplasty

Component positioning is a key factor for avoiding complications and improving functional outcomes in reverse shoulder arthroplasty. Preoperative planning can improve component positioning. However, translating the preoperative plan into the surgical procedure can be challenging. This is particularly the case for the glenoid component positioning in severe deformity or limited visualization of the scapula. Different computational-assisted techniques have been developed to aid implementation of the preoperative plan into the surgical procedure. Navigated augmented reality (AR) refers to the real world augmented with virtual real-time information about the position and orientation of instruments and components. This information can be presented through a head-mounted display (HMD), which enables the user to visualize the virtual information directly overlaid onto the real world. Navigated AR systems through HMD have been validated for shoulder arthroplasty using phantoms and cadavers. This article details a step-by-step guide use of a navigated AR system through HMD, in the placement of the glenoid bony-augmented component.

Influence of glenoid wear pattern on glenoid component placement accuracy in shoulder arthroplasty.

BackgroundAccurate glenoid component placement in shoulder arthroplasty is often difficult even with the use of preoperative planning. Computer navigation and patient-specific guides increase component placement accuracy, but which patients benefit most is unknown. Our purpose was to assess surgeons' accuracy in placing a glenoid component in vivo using 3-dimensional preoperative planning and standard instruments among various glenoid wear patterns.MethodsWe conducted a retrospective review of 170 primary anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) performed at a single institution. Commercially available preoperative planning software was used in all arthroplasties with multiplanar 2-dimensional computed tomography and a 3-dimensional implant overlay. After registration of intraoperative bony landmarks to the navigation system, participating surgeons with knowledge of the preoperative plan were blinded to the computer screen and attempted to implement their preoperative plan by simulating placement of a central-axis glenoid guide pin. Two hundred thirty-three screenshots of surgeon's simulated guide pin placement were included. Glenoid displacement, error in version and inclination, and overall malposition from the preoperatively planned target point were stratified by posterior wear status (with [Walch B2 or B3] or without [A1, A2, or B1]) and Walch classification (A1, A2, B1, B2, or B3). The glenoid component was considered malpositioned when version or inclination errors exceeded 10° or the starting point displacement exceeded 4 mm.ResultsFor rTSA, errors in version were greater for glenoids with posterior wear compared with those without (8.1° ± 5.6° vs. 4.7° ± 4.0°; P < .001). On post hoc analysis, B2 glenoids had greater version error than A1, A2, and B1 glenoids. A greater proportion of glenoids undergoing rTSA that possessed posterior wear had an error in version >10° compared with those without (31% vs. 8%; P < .001). Consequently, glenoids undergoing rTSA with posterior wear were malpositioned at a greater rate compared with those without (73% vs. 53%). In contrast, glenoids undergoing aTSA with and without posterior wear did not differ based on displacement error, version error, inclination error, or malposition occurrence.ConclusionsPosterior glenoid bone loss more commonly resulted in glenoid version errors exceeding 10 degrees and component malposition in rTSA, but not for aTSA. Malposition was still relatively high in patients without significant posterior wear for both aTSA (36%) and rTSA (53%). Surgeons should consider alternate techniques beyond preoperative planning and standard instrumentation when performing shoulder arthroplasty in patients with posteriorly worn glenoids.

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

BackgroundThe 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.MethodsThe 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.ResultsThere 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).ConclusionNo 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.

Does fluoroscopy improve baseplate position compared to conventional technique in reverse shoulder arthroplasty? A preliminary study.

Accurate placement of glenoid component in reverse shoulder arthroplasty remains a challenge for surgeons of all levels of expertise; however, no studies have evaluated the utility of fluoroscopy as a surgical assistance method. Prospective comparative study of 33 patients undergoing primary reverse shoulder arthroplasty during a 12-month period. Fifteen patients had a baseplate placed using the conventional "free hand" technique (control group), and 18 patients using intraoperative fluoroscopy assistance group, in a case-control design. Postoperative glenoid position was evaluated on postoperative Computed Tomography (CT) scan. The mean deviation of version and inclination for fluoroscopy assistance vs. control group was 1.75° (0.675-3.125) vs. 4.2° (1.975-10.45) (p = .015), and 3.85° (0-7.225) vs. 10.35° (4.35-18.75) (p = .009). The distance from the central peg midpoint to the inferior glenoid rim (fluoroscopy assistance 14.61 mm/control 4.75 mm, p = .581) and the surgical time (fluoroscopy assistance 1.93 ± 0.57/control 2.18 ± 0.44 h, p = .400) showed no differences, with an average radiation dose of 0.45 mGy and fluoroscopy time of 14 s. Accurate axial and coronal scapular plane positioning of glenoid component is improved with intraoperative fluoroscopy at the cost of a greater radiation dose and without differences in surgical time. Comparative studies are needed to determine whether their use in relation to more expensive surgical assistance systems result in similar effectiveness.L evel of evidence : Level III, therapeutic study.

Does computerized CT-based 3D planning of the humeral head cut help to restore the anatomy of the proximal humerus after stemless total shoulder arthroplasty?

Restoration of proximal humeral anatomy (RPHA) after total shoulder arthroplasty (TSA) has been shown to result in better clinical outcomes than is the case in nonanatomic humeral reconstruction. Preoperative virtual planning has mainly focused on glenoid component placement. Such planning also has the potential to improve anatomicpositioning of the humeral head by more accurately guiding the humeral head cutand aid in the selection of anatomic humeral component sizing. It was hypothesized that the use of preoperative 3-dimensional (3D) planning helps to reliably achieve RPHA after stemless TSA. One hundred consecutive stemless TSA (67 males, 51 right shoulder, mean age of 62 ±9.4 years) were radiographically assessed using pre- and postoperative standardized anteroposterior radiographs. The RPHA was measured with the so-called circle method described by Youderian etal. We measured deviation from the premorbid center of rotation (COR), and more than 3 mm was considered as minimal clinically important difference. Additionally, pre- and postoperative humeral head diameter (HHD), head-neck angle (HNA), and humeral head height (HHH) were measured to assess additional geometrical risk factors for poor RPHA. The mean distance from of the premorbid to the implanted head COR was 4.3± 3.1 mm. Thirty-five shoulders (35%) showed a deviation of less than 3 mm (mean 1.9±1.1) and 65 shoulders (65%) a deviation of ≥3 mm (mean 8.0 ± 3.7). Overstuffing was the main reason for poor RPHA (88%). The level of the humeral head cut was responsible for overstuffing in 46 of the 57 overstuffed cases. The preoperative HHD, HHH, and HNA were significantly larger, higher, and more in valgus angulation in the group with accurate RPHA compared with the group with poor RPHA (HHD of 61.1 mm ± 4.4 vs. 55.9 ± 6.6, P < .001; HHH 8.6±2.2 vs. 7.6±2.6, P= .026; and varus angulation of 134.7° ±6.4° vs. 131.0° ±7.91, P = .010). Restoration of proximal humeral anatomy after stemless TSA using computed tomography (CT)-based 3D planning was not precise. A poorly performed humeral head cut was the main reason for overstuffing, which was seen in 88% of the cases with inaccurate RPHA. Preoperative small HHD, low HHH, and varus-angulated HNA are risk factors for poor RPHA after stemless TSA.

Uncemented fixation of a monoblock ingrowth polyethylene glenoid: early follow-up

Traditional monoblock pegged glenoid components are implanted with cement, increasing operative time and potentially violating more bone than those inserted without cement. We study the early radiographic loosening and reoperation rate following uncemented fixation of a hybrid cage monoblock polyethylene glenoid component. Between 2013 and 2015, a total of 51 shoulders underwent anatomic shoulder arthroplasty (TSA) using a hybrid ingrowth cage polyethylene glenoid component by a single surgeon, with a minimum follow-up of 2 years. In all cases, the glenoid component was placed without cement. Mean follow-up was 33 months (range, 24-57). The primary outcome was Lazarus scale-assessed radiographic loosening. Secondary outcomes included reoperation, range of motion (ROM), and patient-reported outcome measures (PROMs). Twelve glenoid components (24%) had radiolucent lines. Glenoid lines were rated grade 1, grade 2, and grade 5 (6, 4, and 2 shoulders, respectively). Six shoulders (12%) had humeral lucent lines. Two shoulders (4%) underwent reoperation, only 1 of these occurring due to isolated failure of the glenoid component. As a group, mean ROM and PROMs improved significantly compared with preoperative values and exceeded the minimal clinically important difference. Glenoid loosening remains a major concern at mid- to long-term follow-up of TSA. Placement of this hybrid cage monoblock polyethylene glenoid component in a completely uncemented fashion does not lead to early clinical loosening, after which bony ingrowth into the central cage can be expected. Uncemented fixation of this hybrid cage component appears to be a safe treatment option for patients undergoing primary TSA.

3D full-field biomechanical testing of a glenoid before and after implant placement

Loosening of the glenoid component is the most common cause of failure of total shoulder arthroplasty. While the underlying mechanisms are not fully understood, mechanical factors are widely reported to play a key role in glenoid component loosening. In this study, mechanical testing coupled with micro X-ray computed tomography (micro-CT) is performed to apply various physiologically realistic loads on a native and implanted glenoid. Digital volume correlation of micro-CT images is used to compute the 3D full-field deformation and strain inside the glenoid. The measured strain distributions are in good agreement with the analytical solutions of beam bending models, especially for anteriorly and posteriorly eccentric loadings. The effective moduli of the overall native and implanted glenoid were similar. However, under the same eccentric loading conditions, implanted glenoid exhibited a wider range of strain, because the placement of glenoid component increases the bending moment inside the glenoid. This proof-of-concept study provides a feasible and powerful method for the study of 3D full-field biomechanics in native and implanted glenoids.

Comparison of axillary lateral radiography with computed tomography in the preoperative characterization of glenohumeral wear patterns and the effects of body mass index on quality of imaging

Background: Preoperative imaging is important in planning glenoid component placement in shoulder arthroplasty. This study compared preoperative axillary lateral radiography with CT to determine which was more effective in characterization of glenoid erosion and subluxation and in measurement of glenoid version. We also sought to determine the effect of body mass index (BMI) on image quality. Methods: Eighty-eight patients who had shoulder arthroplasty for primary glenohumeral osteoarthritis were included. The Walch and Mayo classifications as well as glenoid version measurements were used. Kappa coefficients were obtained for interclass and intraclass reliabilities. Intraclass and interclass correlation coefficients were calculated for glenoid version measurements. Results: For glenoid erosion and subluxation, intraobserver and interobserver reliabilities indicated moderate (k=0.19-0.28) and fair agreement (k=0.41-0.50), respectively, which were similar for both imaging modalities and classifications. For glenoid version, interobserver reliability was good for both modalities, but intraobserver reliability showed substantial agreement for CT and only good agreement for radiographs (k=0.77, k=0.91, k=0.65-0.7, respectively). Increased BMI negatively affected image quality in both but more so on radiographs (P&lt;0.0001). Conclusions: Both modalities had similar intraobserver and interobserver agreement; however, CT provided significantly more precise measurements of glenoid version regardless of classification used. A high BMI significantly affected the observers’ ability to judge classifications, especially on radiographs.

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

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. 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. 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. 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.

Novel 3-dimensionally printed patient-specific guide improves accuracy compared with standard total shoulder arthroplasty guide: a cadaveric study

BackgroundPatient-specific instrumentation (PSI) systems for total shoulder arthroplasty (TSA) can improve glenoid component placement, but may involve considerable expense and production delays. The purpose of this study was to evaluate a novel technique for in-house production of 3-dimensionally printed, patient-specific glenoid guides. We hypothesized that our PSI guide would improve the accuracy of glenoid guide pin placement compared with a standard TSA guide.MethodsWe randomized 20 cadaveric shoulders to receive pin placement via the PSI guide (n = 10, study group) or standard TSA guide (n = 10, control group). PSI guides were designed to fit each glenoid based on 3-dimensional scapular models constructed from computed tomography scans. A presurgical plan was created for the guide pin trajectory in neutral version and inclination based on individual scapular anatomy. After pin placement, 3-dimensional models from repeated computed tomography scans were superimposed to calculate deviation from the presurgical plan for each specimen.ResultsInclination deviation was significantly lower in the PSI group than in the standard guide group (1.5° ± 1.6° vs. 6.4° ± 5.0°, P = .009). The glenoid entry site exhibited significantly less deviation in the PSI group (0.8 ± 0.6 mm vs. 2.1 ± 1.2 mm, P = .008). The average production cost and time for the PSI guides were $29.95 and 4 hours 40 minutes per guide, respectively.ConclusionsThe PSI guide significantly improved the accuracy of glenoid pin placement compared with the standard TSA guide. Our PSI guides can be produced in-house, inexpensively, and with substantially reduced time compared with commercially available guides.

Sex and side differences of three-dimensional Glenoid anthropometric parameters in a normal Turkish population

Aim: Due to anatomical differences, current baseplate designs may lead to incompatibilities in reverse shoulder arthroplasty in different populations. We hypothesized that glenoid anthropometric parameters in Turkish subjects would be different from that in other populations.Material and Methods: Three-dimensional morphology of 200 healthy Turkish shoulders (100 male and 100 females, 93 left and 107 right shoulders) was evaluated. Glenoid height, width, version, inclination, circumference, and surface area; glenoid depth, scapular neck length, and scapular neck angle were measured. Sex and side differences were assessed. The correlation between glenoid morphologic parameters and subject height was assessed. The height corresponding to a 25-mm glenoid width was predicted.Results: There was a significant difference between male and female subjects regarding glenoid height, width, version, depth, circumference, surface area, and patient height (p0.05). Also, there was a significant difference between right and left shoulders regarding glenoid height, glenoid width, glenoid version, glenoid surface area, superior depth, central depth, and inferior depth measurements (p0.05). The glenoid height, width, retroversion, depth, circumference and surface area was well correlated with subject height. The estimated body height value to be obtained for a 25 mm glenoid width value was calculated as 164.4 cm.Conclusion: Our results would be useful in patient selection, preoperative planning, determining the appropriate glenosphere sizes and glenoid component placement. The values of measurement parameters in this study may serve as reference values for normal Turkish population and may be helpful in the comparisons with other populations and osteoarthritic glenoids.

Paper #5 - Three-dimensional preoperative planning and patients specific instrumentation improve glenoid component positioning

Introduction: The use of three-dimensional (3-D) preoperative planning and patient specific surgical instrumentation (PSI) have been shown to improve surgeon accuracy in achieving desired glenoid implant position during total shoulder arthroplasty (TSA). While a number of PSI tools are currently available for glenoid guide pin placement in TSA, no studies to date have compared technologies against each other. The purpose of this study is to evaluate the use of 3-D preoperative planning with and without the use of different PSI tools in TSA to compare the accuracy of glenoid component placement across groups and to historical controls using standard two-dimensional (2-D) imaging and standard instrumentation. We hypothesize that the use of PSI technology will improve accuracy compared to standard instrumentation with standard 2-D imaging or 3-D preoperative planning alone, particularly in cases with more severe preoperative glenoid pathology.