Positioning Of Glenoid Component Research Articles

A Short-term clinical and radiologic outcomes of reverse total shoulder arthroplasty with navigation system in Asian population: A retrospective comparative study

BackgroundIn reverse total arthroplasty (rTSA), glenoid component positioning is a critical factor for outcomes especially in Asian population with smaller glenoid. The purpose of this study was to compare the clinical and radiologic outcomes of rTSA with and without the navigation system with a minimum follow-up of two years in Asian population. MethodsThis was a retrospective comparative study of 33 rTSA with the navigation system (NAV group) and 40 conventional rTSA (CON group). Radiologic measurements regarding the position of the glenoid component, glenoid vault perforation by the central cage, and scapular notching, as well as clinical outcomes including range of motion (ROM), functional scores and complications were compared. Number, length, and angulation of screws were assessed. ResultsThe mean age was 73.9 ± 5.9 years with a mean follow-up of 30.1 ± 6.4 months. The NAV group more frequently utilized augmented baseplate (P < 0.001), showed less superior inclination (P = 0.030) and had lower incidence of glenoid vault perforation (P = 0.040). The length of superior (P = 0.001) and inferior screws (P = 0.045) was longer in the NAV group. In the NAV group compared to the CON group, more inferior orientation of superior screws (P < .001), more anterior orientation for inferior screws (P = 0.031), and anterior screws (P = 0.003) were observed. The NAV group showed significantly less penetration into the suprascapular fossa by a superior screw (P = 0.007). Final ROM, functional scores, and complications showed no significant differences between two groups. ConclusionIn short-term follow-up, the use of a navigation system in rTSA showed no significant difference in clinical outcomes and complications compared to conventional implantation. However, it enabled a lower superior inclination and a reduced glenoid vault perforation by the central cage, simultaneously allowing for the insertion of longer peripheral screws in a safer direction compared to conventional implantation.

An in vitro comparison of mixed-reality navigation to traditional freehand and patient-specific instrumentation techniques for glenoid guide pin insertion during shoulder arthroplasty

BackgroundAccurate insertion of the glenoid guide pin in shoulder arthroplasty (RSA) is important for obtaining optimized glenoid component position and orientation. The objective of this study was to evaluate and compare the accuracy of three glenoid guide pin insertion techniques: 1) traditional software planning using freehand guide pin insertion (freehand), 2) guide pin insertion utilizing patient-specific instrumentation (PSI), and 3) using a mixed reality navigation (MR-NAV) system. MethodsTwenty (20) computer tomography (CT) scans were obtained from patients exhibiting glenoid erosion patterns according to the Walch and Favard classifications. Cases were planned using validated three-dimensional (3D) preoperative planning software. The CT data was then used to 3D print triplicate plastic models of each glenoid to evaluate the three guide pin insertion techniques. The first technique employed traditional software planning with freehand guide pin insertion. The second method used preoperatively planned PSI guides, while the third utilized a MR-NAV system, which provided real-time holographic guidance during guide pin insertion. Once all guide pins had been inserted into the models, an independent optical tracking system and custom digitization device was used to quantify the position and orientation of each guide pin relative to the glenoid. The outcomes for this study included the absolute mean error in guide pin inclination, version, and entry point relative to the preoperative plan. The absolute Total Global Error was also assessed, which was defined as the sum of the absolute guide pin orientation and position error relative to the preoperative plan. ResultsNo statistically significant differences between MR-NAV and PSI were found for the inclination error (2±1° versus 2±1°; P=0.056), version error (1±1° versus 1±1°; P=1.000), and Total Global Error (5±1 [mm+deg] versus 5±1 [mm+deg], P=1.000), respectively. The freehand technique produced significantly greater error than MR-NAV and PSI for inclination (5±3°, P≤0.017), version (4±3°, P≤0.032) and Total Global Error (8±3 [mm+deg], P<0.001). No statistically significant differences in the entry point error were observed between all guide pin insertion methods (P≥0.058). DiscussionThese results demonstrate that the precision and accuracy of MR-NAV is comparable to PSI and superior to a freehand technique for glenoid guide pin insertion in-vitro. Further study is needed to compare the accuracy of these techniques intra-operatively, in addition to assessing a potential learning curve between surgeons of varying experience with the MR-NAV system.

Intraoperative Navigation in Reverse Shoulder Arthroplasty: Advantages and Future Prospects.

Intraoperative navigation is a novel technology that can provide real-time feedback to the surgeon during implantation and enhance the accuracy and precision of glenoid component positioning. Applications of intraoperative navigation systems have demonstrated increased precision in baseplate version and inclination, as well as improved baseplate screw placement, with fewer screws used and greater purchase length achieved when compared to standard instrumentation. Early clinical studies have shown favorable results, with significantly improved patient-reported and clinical outcomes and decreased complications. The implementation of intraoperative navigation is associated with a short learning curve and a minimal increase in operative time. Nevertheless, further research is necessary to substantiate the clinical benefit of navigation and evaluate its economic cost-effectiveness and impact on implant survival. Augmented reality and robotic-assisted surgery are additional emerging technologies that, while novel, hold the potential to further advance the field of shoulder arthroplasty.

DYNAMIC 3D ANIMATION OPTIMIZING GLENOSPHERE CONFIGURATION IN REVERSE SHOULDER ARTHROPLASTY

Scapular notching is a common problem following reverse shoulder arthroplasty (RSA). This is due to impingement between the humeral polyethylene cup and scapular neck in adduction and external rotation. Various glenoid component strategies have been described to combat scapular notching and enhance impingement-free range of motion (ROM). There is limited data available detailing optimal glenosphere position in RSA with an onlay configuration. The purpose of this study was to determine which glenosphere configurations would maximise impingement free ROM using an onlay RSA prosthesis.A three-dimensional (3D) computed tomography (CT) scan of a shoulder with Walch A1, Favard E0 glenoid morphology was segmented using validated software. An onlay RSA prosthesis was implanted and a computer model simulated external rotation and adduction motion of the virtual RSA prosthesis. Four glenosphere parameters were tested; diameter (36mm, 41mm), lateralization (0mm, 3mm, 6mm), inferior tilt (neutral, 5 degrees, 10 degrees), and inferior eccentric positioning (0.5mm, 1.5mm. 2.5mm, 3.5mm, 4.5mm). Eighty-four combinations were simulated. For each simulation, the humeral neck-shaft angle was 147 degrees and retroversion was 30 degrees.The largest increase in impingement-free range of motion resulted from increasing inferior eccentric positioning, gaining 15.0 degrees for external rotation and 18.8 degrees for adduction. Glenosphere lateralization increased external rotation motion by 13. 6 degrees and adduction by 4.3 degrees. Implanting larger diameter glenospheres increased external rotation and adduction by 9.4 and 10.1 degrees respectively. Glenosphere tilt had a negligible effect on impingement-free ROM.Maximizing inferior glenosphere eccentricity, lateralizing the glenosphere, and implanting larger glenosphere diameters improves impingement-free range of motion, in particular external rotation, of an onlay RSA prosthesis. Surgeons’ awareness of these trends can help optimize glenoid component position to maximise impingement-free ROM for RSA. Further studies are required to validate these findings in the context of scapulothoracic motion and soft tissue constraints.

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.

Assessing glenoid arthroplasty component positioning for surgeons utilizing surgical planning software

BackgroundGlenoid component positioning remains a challenge during total shoulder arthroplasty (TSA). While preoperative three-dimensional (3D) planning software is widely available for most TSA systems today, the degree to which this software affects surgeon preoperative and intraoperative decision-making is unknown. The purpose of the study is to determine if surgeons using 3D planning software adhere to their preoperative plan and whether or not the operative plan follows glenoid component positioning guidelines for anatomic TSA (aTSA) and reverse TSA (rTSA). MethodsA total of 695 consecutive, de-identified, planned surgeries using commercially available software were identified from the case registries of six fellowship-trained shoulder arthroplasty surgeons and reviewed retrospectively. Each preoperative plan was reviewed to assess morbid glenoid version/inclination and glenoid component position. aTSA glenoid plans were evaluated for the final implant position with less than 10° of retroversion, corrective reaming less than 15°, and avoidance of glenoid vault perforation. rTSAs were evaluated for the final implant position with less than 15° of retroversion, glenosphere position in neutral or inferior tilt with at least 3 mm of inferior offset and 3 mm of posterior offset, and backside coverage of at least 50% of the baseplate on the glenoid face. Analyses were performed to determine surgeon adherence to these guidelines and variance with specific deformity patterns. Analysis of variance was performed to determine whether glenoid size resulted in selection of differing implant sizes by surgeons. The rate at which surgeon planned component size correlated with the actual implant size utilized in surgery was also evaluated. Results185 aTSAs and 510 rTSAs preoperatively planned surgeries using commercially available software were analyzed. All planning guidelines were adhered to in 90% of all aTSA cases and 79% of all rTSA cases. The concordance, or matching, between preoperative 3D planning implant selection and final implant selection was 90% for aTSA and 91% and 95% for rTSA baseplate and glenosphere implant selection, respectively. Implant size varied in accordance with glenoid size for both aTSA and rTSA (P < .001). ConclusionSurgeons adhered to known guidelines in most TSA cases when utilizing 3D computed tomography-based shoulder arthroplasty planning software. A high concordance was found between preoperative implant selection and the final glenoid component inserted. Understanding how orthopedic surgeons utilize planning software can help lead to improvements in software design.

The Glenoid Vault Outer Cortex (GVOC) radiological reference for shoulder arthroplasty evaluated in aging scapulae

BackgroundAccurate glenoid component positioning is an important determinant of outcome in a shoulder arthroplasty surgery. Optimal glenoid placement is determined using bony landmarks of the scapula. The Glenoid Vault Outer Cortex (GVOC) has been recently described as a new, more accurate radiological reference. This has, however, only been evaluated against current standard references in young patients. Further investigation of the GVOC in older patients is therefore warranted. We, therefore, evaluated the effect of aging on the accuracy and stability of the GVOC, in determining glenoid anatomy as compared to the commonly used Scapular Border (SB) plane. MethodsComputed tomography imaging of 129 individual scapulae was obtained retrospectively from a cohort of patients who had undergone either total body or region-specific computed tomography imaging which included the shoulder region. This comprised of 35 males and 33 females (64 and 65 scapulae respectively) who were aged from 30 to 92 years. Imaging of 54 scapulae was from patients aged ≥60 years. The accuracy of the GVOC plane was then assessed against the SB plane. ResultsIn all patients, the mean difference between estimates using the GVOC plane and the GR (actual) was 2.2° (standard deviation [SD], 4.2) for version, and 1.8° (SD, 4.9) for inclination (P < .001). This contrasted with values of 7.6° (SD, 7.6) for version, and 22.9° (SD, 10.8) for inclination when using the SB reference plane (P < .001). Within the group aged ≥60 years, the mean difference between estimates using the GVOC plane and the glenoid rim (actual) was 3.2° (SD, 4.7) for version and 1.9° (SD, 3.1) for inclination, (P < .001). This contrasted to 10.0° (SD, 7.2) for version, and 23.4° (SD, 10.7) for inclination when using the SB plane (P < .001).Separately it was noted that the GVOC’s relationship to the glenoid rim remained constant throughout aging as opposed to the SB which changed significantly over time effecting estimates of glenoid retroversion. ConclusionsThe GVOC is a new plane of reference developed specifically for the use in shoulder arthroplasty. It is shown to be more accurate and stable in the aging scapulae than the currently used SB plane. The future development of guides and planning softwares that utilize the GVOC may provide an important opportunity for improved accuracy and outcome in shoulder arthroplasty.

Glenoid Component Position Does Not Affect Short-Term Clinical and Radiologic Outcomes in Total Shoulder Arthroplasty.

Background: Malpositioning of the glenoid component in total shoulder arthroplasty (TSA) remains the primary source of loosening. The purpose of this study is firstly, to quantify postoperative glenoid component position in patients having a TSA and secondly, to explore whether glenoid component radiolucency is associated with glenoid position, clinical outcomes and patient-reported measures in the short-term (two year) follow-up period. Methods: This study was a sub-study of a larger clinical trial that included patients who underwent a TSA and who were randomized into two different glenoid types with a minimum two-year follow-up period. Post-operative radiographic assessments (six weeks and two years) were used to measure glenoid component position (version, inclination, offset) and humeral head centering anterior–posterior (AP) and superior–inferior (SI), and to assess glenoid component radiolucent scoring (modified Lazarus). Pre-operative X-rays were used to measure glenoid version, inclination and Walch classification. Patient-reported measures (PROMs) included the EQ-5D health slider and the Western Ontario Osteoarthritis (WOOS) and American Shoulder and Elbow Surgeons (ASES) score and were captured at baseline and two years postoperative. Clinical outcomes including range of motion and complications were also documented. Statistical analysis included t-tests and regression modeling. Results: Ninety-one patients with an average age of 69.9 ± 6.2 years were included in this study. Glenoid component position improved significantly in version (−19.4 ± 8.6° to −17.7 ± 8.5°; p < 0.045) and inclination (11.5 ± 7.1° to 5.9 ± 6.3°; p < 0.00001) from preoperative to six weeks postoperative. Glenoid component offset in SI and humeral head centering in AP remained unchanged throughout the follow-up. Radiolucency (Lazarus classification) was recorded in 21 cases (17.3%) with a Lazarus score of 1 (15 cases) and 2 (6 cases). The EQ-5D health slider, WOOS and ASES, and ROM confirmed continuous improvements from the preoperative scores to the two-year follow-up (p < 0.05). Regression models showed no correlation between glenoid component radiolucency at two years and the postoperative week six glenoid component position; however, female gender was a significant variable. Conclusion: Glenoid component changes from its original native glenoid were observed following TSA. Glenoid inclination was improved more than version from baseline, and the humeral head remained well-centered in AP and SI at two years. Radiolucency of the glenoid at two years is not negatively associated with PROMs or component position; however, female gender was identified as a significant predictor and warrants further investigation. Complications are not associated with glenoid position or radiolucency, but longer-term follow-up is required.

Computer-Assisted Preoperative Planning and Patient-Specific Instrumentation for Glenoid Implants in Shoulder Arthroplasty.

Glenoid component positioning affects implant survival after total shoulder arthroplasty, and accurate glenoid-component positioning is an important technical aspect. The use of virtual planning and patient-specific instrumentation has been shown to produce reliable implant placement in the laboratory and in some clinical studies. Currently available preoperative planning software programs employ different techniques to generate 3-dimensional models and produce anatomic measurements potentially affecting clinical decisions. There are no published data, to our knowledge, on the effect of preoperative computer planning and patient-specific instrumentation on long-term clinical outcomes.

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.

Relationship Between Glenoid Component Shift and Osteolysis After Anatomic Total Shoulder Arthroplasty: Three-Dimensional Computed Tomography Analysis.

The purpose of this study was to evaluate glenoid component position and radiolucency following anatomic total shoulder arthroplasty (TSA) using sequential 3-dimensional computed tomography (3D CT) analysis. In a series of 152 patients (42 Walch A1, 16 A2, 7 B1, 49 B2, 29 B3, 3 C1, 3 C2, and 3 D glenoids) undergoing anatomic TSA with a polyethylene glenoid component, sequential 3D CT analysis was performed preoperatively (CT1), early postoperatively (CT2), and at a minimum 2-year follow-up (CT3). Glenoid component shift was defined as a change in component version or inclination of ≥3° from CT2 to CT3. Glenoid component central anchor peg osteolysis (CPO) was assessed at CT3. Factors associated with glenoid component shift and CPO were evaluated. Glenoid component shift occurred from CT2 to CT3 in 78 (51%) of the 152 patients. CPO was seen at CT3 in 19 (13%) of the 152 patients, including 15 (19%) of the 78 with component shift. Walch B2 glenoids with a standard component and glenoids with higher preoperative retroversion were associated with a higher rate of shift, but not of CPO. B3 glenoids with an augmented component and glenoids with greater preoperative joint-line medialization were associated with CPO, but not with shift. More glenoid component joint-line medialization from CT2 to CT3 was associated with higher rates of shift and CPO. A greater absolute change in glenoid component inclination from CT2 to CT3 and a combined absolute glenoid component version and inclination change from CT2 to CT3 were associated with CPO. Neither glenoid component shift nor CPO was associated with worse clinical outcomes. Postoperative 3D CT analysis demonstrated that glenoid component shift commonly occurs following anatomic TSA, with increased inclination the most common direction. Most (81%) of the patients with glenoid component shift did not develop CPO. Longer follow-up is needed to determine the relationships of glenoid component shift and CPO with loosening over time. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Radiographic changes around the glenoid component in primary reverse shoulder arthroplasty at mid-term follow-up

Some local events after reverse shoulder arthroplasty (RSA) occur without the patient experiencing symptoms and yet may be detected on diagnostic imaging, thereby serving as indicators of future complications that may require revision. Most of these events involve the glenoid component, but radiographic studies evaluating this component are scarce, especially medium- and long-term studies. This study aimed to analyze the radiographic changes around the glenoid component and determine the risk factors associated with the presence of these radiographic changes. A retrospective review of 105 primary Grammont-style RSAs implanted between 2003 and 2014 was conducted. Radiographic outcomes were evaluated in patients with ≥5 years of radiographic follow-up. Standardized digital radiographs obtained immediately postoperatively and at a minimum follow-up time of 5 years were analyzed to determine (1) glenoid component position (inclination and height) and (2) minor radiographic changes (Sirveaux grade 1 or 2 scapular notching; nondisplaced acromial fracture; radiolucent lines around 1 or 2 screws; Brooker grade 1a, 1b, or 2 heterotopic calcifications; or single screw rupture), as well as major radiographic changes (Sirveaux grade 3 or 4 scapular notching; radiolucent lines around ≥3 screws or central peg; Brooker grade 1c or 3 heterotopic calcifications; prosthetic dislocation; loosening or migration; or disassembly). Major radiologic changes were identified in 14.3% of the cases. Bivariate analysis showed that more changes were associated with the arthroplasties implanted in the first years of the study (odds ratio [OR] = 0.81, P = .012). This time-related variable was also associated with inclination (OR = 0.88, P = .045) and height (OR = 0.75, P = .001), improving in arthroplasties implanted in the last years of the study. Multivariate analysis revealed an increased risk of severe scapular notching mainly associated with superior tilt (OR = 2.52, P = .036) and a high (OR = 2.68, P = .019) or excessively high (OR = 7.55, P = .013) position and an increased risk of loosening signs associated with superior tilt (OR = 8.92, P = 9.1 × 10-6). The percentage of radiologic changes of the glenoid component in RSA is considerable, despite the detection of a decrease in their presence among the arthroplasties implanted outside the initial period. Superior tilt and an excessively high position appear to be associated with a severe degree of scapular notching development and increased risk of radiographic loosening signs. Knowledge of the factors associated with major radiologic changes in the medium-term follow-up will help to optimize the primary surgical technique for each patient and indication, improving implant survival in primary RSA surgery.

Pre-Operative CT-Based Planning Integrated With Intra-Operative Navigation in Reverse Shoulder Arthroplasty: Data Acquisition and Analysis Protocol, and Preliminary Results of Navigated Versus Conventional Surgery.

Reverse total shoulder arthroplasty (RSA) successfully restores shoulder function in different conditions. Glenoid baseplate fixation and positioning seem to be the most important factors influencing RSA survival. When scapular anatomy is distorted (eccentric osteoarthrirtis, rotator cuff arthropathy), optimal baseplate positioning and secure screw purchase can be challenging. The aim of this study was to evaluate whether CT-based pre-operative planning, integrated with intra-operative navigation could improve glenoid baseplate fixation and positioning by increasing screw length, reducing number of screws required to obtain fixation and increasing the use of augmented baseplate to gain the desired positioning. Twenty patients who underwent navigated RSA were compared retrospectively with 20 patients operated on with a conventional technique. All the procedures were performed by the same surgeon, using the same implant. Mean screw length was significantly longer in the navigation group (35.5 ± 4.4 mm vs 29.9 ± 3.6 mm; p = .001). Significant higher rate of optimal fixation using 2 screws only (17 vs 3 cases, p = .019) and higher rate of augmented baseplate usage (13 vs 4 cases, p = .009) was also present in the navigation group. Pre-operative CT-based planning integrated with intra-operative navigation can improve glenoid component positioning and fixation, possibly leading to an improvement of RSA survival.

Impact of preoperative 3-dimensional planning and intraoperative navigation of shoulder arthroplasty on implant selection and operative time: a single surgeon's experience

Preoperative 3D planning and intraoperative navigation for shoulder arthroplasty has recently gained interest because of the potential to enhance the surgeon's understanding of glenoid anatomy and improve the accuracy of glenoid component positioning. The purpose of our study was to assess the impact of preoperative 3D planning on the surgeon's selection of the glenoid component (standard vs. augmented) and compare duration of surgery with and without intraoperative navigation. We retrospectively analyzed 200 consecutive patients who underwent shoulder arthroplasty. The first group of 100 patients underwent shoulder arthroplasty using standard 2D preoperative planning based on standard radiographs and computed tomographic scans. The second group of 100 patients underwent shoulder arthroplasty using 3D preoperative planning and intraoperative navigation. Type of glenoid component and operative time were recorded in each case. For the group of patients with standard preoperative planning, only 15 augmented glenoid components were used, whereas in the group of patients with 3D preoperative planning and navigation, 54 augments were used (P < .001). The operative time was 11 minutes longer for the procedures that used intraoperative navigation, compared with those that did not (P < .001). This difference diminished as the surgeon became more proficient with the navigation technique. Use of preoperative 3D planning changes the surgeon's understanding of the patient's glenoid anatomy. In our study, using 3D planning increased the likelihood that the surgeon selected an augmented glenoid component compared with 2D planning. Intraoperative navigation slightly lengthened the duration of surgery, but this became insignificant as part of a learning curve within 6 months.

The influence of glenoid component position on scapular notching: a detailed radiographic analysis at midterm follow-up

BackgroundGlenoid baseplate and glenosphere positioning may affect scapular notching rates. The purpose of this study was to assess various radiographic parameters and correlate them with scapular notching after primary reverse total shoulder arthroplasty (RTSA) at a minimum follow-up time of 5 years.MethodsThe study sample included 147 primary RTSA with good-quality postoperative radiographs at least 5 years after implantation (mean follow-up 6.1 years, range 5-12 years). The center of rotation (COR) of the glenosphere in reference to the bone-baseplate interface was medialized in 71 and lateralized in 76 shoulders, with a varus polyethylene opening angle in 134 shoulders. Preoperative and immediate postoperative radiographs were measured to determine (1) glenoid baseplate inclination: α, β, and the reverse shoulder arthroplasty (RSA) angles; (2) glenoid component inferiorization—peg glenoid rim distance (PGRD); and (3) sphere bone overhang distance (SBOD). Scapular notching was graded according to the Sirveaux classification.ResultsScapular notching was noted in 98 shoulders (67%) and classified as grade 1 in 46, grade 2 in 25, grade 3 in 20, and grade 4 in 7. There were statistically significant associations between notching and both medialized glenospheres (91% vs. 45%, P = .001) and varus polyethylene angle (P = .0001). The mean postoperative RSA angle, PGRD, and SBOD were 6.6 degrees, 23.8 mm, and +2.6 mm, respectively. Preoperative α and postoperative β, RSA, PGRD, and SBOD were all associated with notching (P < .05). The rate of reoperation was 2.7% at a minimum of 5 years, with reasons for reoperation related to component failure in only one shoulder.ConclusionScapular notching correlates with glenoid and baseplate inclination, baseplate inferiorization, inferior glenosphere overhang, glenosphere COR, humeral polyethylene angle, and longer clinical follow-up. SBOD is a clinically useful measurement with decreased values associated with notching. It is the superior measurement in implants with eccentric glenospheres. Moderate or severe notching was seen in only approximately 15% of the shoulders. Revision surgery was extremely low in this cohort, and it was not related to notching or instability.

Pre-operative planning for reverse shoulder replacement: the surgical benefits and their clinical translation

With the increasing use of reverse shoulder arthroplasty and its expanding indications, surgeons today are facing tougher reconstructive challenges while still providing the patient with a good clinical outcome. There are a greater number of primary and revision cases where glenoid vault deformity is encountered. This presents a challenge to the surgeon during glenoid component positioning. He or she must place the implants in a location and orientation that optimizes range of motion and stability while minimizing impingement. In order to address this, surgeons can look to the use of 3D imaging in order to better understand each patient’s pathology. With the use of virtual planning the surgeon has the ability to arrive in the operating room with an established surgical plan in order to better address the deformity present. This can help in determining if glenoid bone grafting, eccentric reaming, or the use of augmented/lateralized components is the best choice in addressing bony deformity and maximizing impingement-free range-of-motion. Furthermore, with the advent of patient specific instrumentation and navigation the surgeon has the means to translate the preoperative plan into the operating room with increased accuracy, thus, decreasing the likelihood of component malposition and its associated complications. In the future, custom implants may grant the surgeon the means to address severe glenoid bone loss that would otherwise not be reconstructable and potentially give the patient improved function.

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

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

Use of Patient-Specific Instrumentation (PSI) for glenoid component positioning in shoulder arthroplasty. A systematic review and meta-analysis.

IntroductionTotal Shoulder Arthroplasty (TSA) anatomical, reverse or both is an increasingly popular procedure but the glenoid component is still a weak element, accounting for 30–50% of mechanical complications and contributing to the revision burden. Component mal-positioning is one of the main aetiological factors in glenoid failure and thus Patient-Specific Instrumentation (PSI) has been introduced in an effort to optimise implant placement. The aim of this systematic literature review and meta-analysis is to compare the success of PSI and Standard Instrumentation (STDI) methods in reproducing pre-operative surgical planning of glenoid component positioning.Material and methodsA search (restricted to English language) was conducted in November 2017 on MEDLINE, the Cochrane Library, EMBASE and ClinicalTrials.gov. Using the search terms “Patient-Specific Instrumentation (PSI)”, “custom guide”, “shoulder”, “glenoid” and “arthroplasty”, 42 studies were identified. The main exclusion criteria were: no CT-scan analysis results; studies done on plastic bone; and use of a reusable or generic guide. Eligible studies evaluated final deviations from the planning for version, inclination, entry point and rotation. Reviewers worked independently to extract data and assess the risk of bias on the same studies.ResultsThe final analysis included 12 studies, comprising 227 participants (seven studies on 103 humans and five studies on 124 cadaveric specimens). Heterogeneity was moderate or high for all parameters. Deviations from the pre-operative planning for version (p<0.01), inclination (p<0.01) and entry point (p = 0.02) were significantly lower with the PSI than with the STDI, but not for rotation (p = 0.49). Accuracy (deviation from planning) with PSI was about 1.88° to 4.96°, depending on the parameter. The number of component outliers (>10° of deviation or 4mm) were significantly higher with STDI than with PSI (68.6% vs 15.3% (p = 0.01)).ConclusionThis review supports the idea that PSI enhances glenoid component positioning, especially a decrease in the number of outliers. However, the findings are not definitive and further validation is required. It should be noted that no randomised clinical studies are available to confirm long-term outcomes.

Proper benefit of a three dimensional pre-operative planning software for glenoid component positioning in total shoulder arthroplasty.

Glenoid loosening after total shoulder arthroplasty (TSA) is influenced by the position of the glenoid component. 3D planning software and patient-specific guides seem to improve positioning accuracy, but their respective individual application and role are yet to be defined. The aim of this study was to evaluate the accuracy of freehand implantation after 3D pre-operative planning and to compare its accuracy to that of a targeting guide. Seventeen patients scheduled for TSA for primary glenohumeral arthritis were enrolled in this prospective study. Every patient had pre-operative planning, based on a CT scan. Glenoid component implantation was performed freehand, guided by 3D views displayed in the operating room. The position of the glenoid component was determined by manual segmentation of post-operative CT scans and compared to the planned position. The results were compared to those obtained in a previous work with the use of a patient-specific guide. The mean error for the central point was 2.89mm (SD ± 1.36) with the freehand method versus 2.1mm (SD ± 0.86) with use of a targeting guide (p = 0.05). The observed difference was more significant (p = 0.03) for more severely retroverted glenoids (> 10°). The mean errors for version and inclination were respectively 4.82° (SD ± 3.12) and 4.2° (SD ± 2.14) with freehand method, compared to 4.87° (SD ± 3.61) and 4.39° (SD ± 3.36) with a targeting guide (p = 0.97 and 0.85, respectively). 3D pre-operative planning allowed accurate glenoid component positioning with a freehand method. Compared to the freehand method, patient-specific guides slightly improved the position of the central point, especially for severely retroverted glenoids, but not the orientation of the component.

Accuracy of Patient-specific Jigs for Glenoid Component Positioning in Total Shoulder Arthroplasty

Accuracy of Patient-specific Jigs for Glenoid Component Positioning in Total Shoulder Arthroplasty