Inconsistencies in Measuring Glenoid Version in Shoulder Arthroplasty: A Systematic Review.

BACKGROUND: Glenoid version is a critical anatomic parameter relied upon by many surgeons to inform preoperative planning for shoulder arthroplasty. Advancements in imaging technology have prompted measurements of glenoid version on various imaging modalities with different techniques. However, discrepancies in how glenoid version is measured within the literature have not been well characterized. METHODS: A literature search was performed by querying PubMed, EMBASE, CINAHL, and Cochrane computerized databases from their inception through December 2023 to identify studies that assessed the relationship between preoperative glenoid version and at least one clinical or radiologic outcome following shoulder arthroplasty. Study quality was assessed via the Methodological Index for Non-Randomized Studies criteria. Imaging modalities and techniques for measuring glenoid version, along with their association with clinical outcomes, were aggregated. RESULTS: Among 61 studies encompassing 17,070 shoulder arthroplasties, 27 studies (44.3%) described explicitly how glenoid version was measured. The most common imaging modality to assess preoperative glenoid version was computed tomography (CT) (63.9%), followed by radiography (23%); 11.5% of studies used a combination of imaging modalities within their study cohort. Among the studies using CT, 56.5% utilized two-dimensional (2D) CT, 41.3% utilized three-dimensional (3D) CT, and 2.2% used a combination of 2D and 3D CT. The use of 3D CT increased from 12.5% of studies in 2012-2014 to 25% of studies in 2018-2020 to 52% of studies in 2021-2023 (ptrend=0.02). Forty-three (70.5%) studies measured postoperative version, most commonly on axillary radiograph (22 [51.2%]); 34.9% of these studies used different imaging modalities to assess pre- and postoperative version. CONCLUSIONS: This systematic review revealed marked discrepancies in how glenoid version was measured and reported in studies pertaining to shoulder arthroplasty. A temporal trend of increased utilization of 3D CT scans and commercial preoperative planning software was identified. Improved standardization of the imaging modality and technique for measuring glenoid version will enable more rigorous evaluation of its impact on clinical outcomes.

Finding the Truth: Cadaver and CT scan Study of Differences in Glenoid Width Size in the Indian Population.

Introduction: Glenoid mass issues have been extensively published in the recent literature. The controversy arose from our need to compare and obtain the appropriate implant size for reverse shoulder arthroplasty patients. Some well-known authors and surgeons say that Indian patients have a smaller glenoid than their Western friends and patients. Therefore, we decided to examine the glenoid size obtained on a computed tomography (CT) scan and the size obtained on a cadaver, preferably the same cadaver in tertiary care medical school. Necessary permissions were obtained from the relatives of the cadaver, the ethical board, the anatomy department, and the radiology department. Materials and Methods: We evaluated 3D CT scans of 100 patients from our medical college during the global pandemic. Of these, we evaluated only 12 patients whose families agreed to postmortem studies and CT scans. Our research focuses on the shoulder of non-orthopedic diseases conducted at KCGMCH and measured the glenoid height, width, and version using a commercially available computer. Results: The mean age of the patients was 38.5 (range 19-59). The mean glenoid height was 33.8 ± 3.2 mm, maximum glenoid width was 24.3 ± 2.2 mm. The mean glenoid version is 3.48 ± 4 retrospectively. The glenoid width appears to be 23-25 mm on CT scan film, which is similar to cadaver studies. Conclusion: The findings from the cadaver study indicate that the average glenoid size is smaller in the Indian demographic when compared to CT scans. Glenoid width is less in one subset of the population, especially female patients than of the average population than Westerners. However, our studies are limited by the small size of the population and a larger study is recommended in our institution in the future. A better understanding of this glenoid size could help us design a smaller glenoid plate plan, especially for patients in the Indian subcontinent.

Gender-specific factors influencing the glenoid version and reference values for it.

BACKGROUND: Glenoid version is an important factor in the evaluation of shoulder stability and shoulder pathologies. However, there are neither established reference values nor known factors that influence the glenoid version, even though valid reference values are needed for diagnostic and orthopaedic surgery like corrective osteotomy and total or reverse shoulder arthroplasty (TSA/RSA). The aim of our population-based study was to identify factors influencing the glenoid version and to establish reference values from a large-scale population cohort. RESULTS: Our study explored the glenoid versions in a large sample representing the general adult population. We investigated 3004 participants in the population-based Study of Health in Pomerania (SHIP). Glenoid version was measured for both shoulders via magnetic resonance imaging (MRI). Associations with the glenoid version were calculated for sex, age, body height, body weight and BMI. The reference values for glenoid version in the central European population range between -9° and 7.5°, while multiple factors are associated with the glenoid version. CONCLUSION: To achieve a reliable interpretation prior to orthopaedic surgery, sex- and age-adjusted reference values are proposed.

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.

Does glenoid version affect the post-operative clinical outcome after repair of posterior labral tear: A retrospective study.

Introduction: Posterior shoulder instability and consequent labral tear have been predominantly associated with retroversion of the bony glenoid and chondrolabral version. However, literature concerning the degree of glenoid and chondrolabral version and clinical outcomes following labral repair is scarce. Methods: A retrospective cohort study was undertaken among patients with posterior shoulder instability who had undergone arthroscopic isolated posterior labral repair. The MRI was used to assess the bony and labral variations of the glenoid using the Friedman method and further categorized as either anteverted or retroverted glenoid. American Shoulder and Elbow Surgeons (ASES), Oxford Shoulder Score (OSS), and Single Assessment Numeric Evaluation (SANE) scores were used to evaluate pre- and postoperative clinical outcomes at a minimum follow-up of one year. Results: 33 shoulder MRIs performed at our institution were available for radiographic analysis. Among the 33 shoulders that underwent posterior shoulder capsulolabral repair, 23 were available for clinical follow-up for at least one year (range, 12-108 months). The mean (±SD) labral version and bony version were -3.98 (±5.68) and -2.83 (±5.20), respectively. The mean (±SD) postoperative ASES, Oxford score, and SANE scores for all participants were 84.04 (±14.14), 43.38 (±3.81), and 78.57 (±17.40), respectively. However, the difference in clinical outcomes in patients with anteverted or retroverted glenoid versions was not statistically significant. Conclusion: Our study concludes a strong correlation between posterior glenohumeral instability and higher degree of glenoid retroversion. Nevertheless, variations in the glenoid version appear to have no significant impact on clinical outcomes. Level of study: Level IV, retrospective cohort.

Three-dimensional evaluation of the transverse rotator cuff muscle's resultant force angle in relation to scapulohumeral subluxation and glenoid vault morphology in nonpathological shoulders.

BACKGROUND: Static posterior subluxation of the humeral head (SPSH) results in glenohumeral osteoarthritis. Treatment strategies for SPSH with or without resulting osteoarthritis remain challenging. There is growing interest in evaluating the rotator cuff muscle volume, fatty infiltration, or forces in osteoarthritic shoulders with SPSH, mainly due to a possible transverse force imbalance. In nonpathological shoulders, the transverse angle of the rotator cuff muscle's resultant force may be associated with scapulohumeral alignment and glenoid vault morphology, despite an assumed transverse force balance. The purpose of this study was to assess the transverse rotator cuff muscle's resultant force angle (TRFA) and its relationship with the scapulohumeral subluxation index (SHSI) and selected glenoid vault parameters using computer modeling. METHODS: Computed tomography scans of 55 trauma patients (age 31 ± 13 years, 36 males) with nonpathological shoulders were analyzed and all measurements performed in 3-dimension. We placed landmarks manually to determine the humeral head center and the rotator cuff tendon footprints. The contours of the rotator cuff muscle cross-sectional areas were automatically predicted in a plane perpendicular to the scapula. Each rotator cuff muscle was divided into virtual vector fibers with homogeneous density. The resultant force vector direction for each muscle, corresponding to the rotator cuff action line, was calculated by vectorially summing the normalized fiber vectors for each muscle, weighted by the muscle trophic ratio. The resultant force vector was projected on the axial plane, and its angle with the mediolateral scapular axis was used to determine TRFA. The SHSI according to Walch, glenoid version angle (GVA), glenoid anteroposterior offset angle (GOA), glenoid depth, glenoid width, and glenoid radius were also evaluated. RESULTS: The mean values for TRFA, SHSI, GVA, GOA, glenoid depth, glenoid width, and glenoid radius were 7.4 ± 4.5°, 54.3 ± 4.8%, -4.1 ± 4.4°, 5.1 ± 10.8°, 3.3 ± 0.6 mm, 20 ± 2 mm, and 33.6 ± 4.6 mm, respectively. The TRFA correlated strongly with SHSI (R = 0.731, P < .001) and GVA (R = 0.716, P < .001) and moderately with GOA (R = 0.663, P < .001). The SHSI was strongly negatively correlated with GVA (R = -0.813, P < .001) and moderately with GOA (R = -0.552, P < .001). The GVA correlated strongly with GOA (R = 0.768, P < .001). In contrast, TRFA, SHSI, GVA, and GOA did not correlate with glenoid depth, width, or radius. CONCLUSION: Despite an assumed balance in the transverse volume of the rotator cuff muscles in nonpathological shoulders, variations exist regarding the transverse resultant force depending on the SHSI, GVA, and GOA. In healthy/nonosteoarthritic shoulders, an increased glenoid retroversion is associated with a decreased anterior glenoid offset.

Average Indian Glenoid Sizes Are Smaller than All Commercially Available Glenoid Components: A Systematic Review.

Background: Despite the variability in glenoid sizes geographically, most of the currently available commercial glenoid component designs are based on the glenoid parameters of the Caucasian population which may not be suitable for the Indian population due to a mismatch between the prosthesis and native anatomy. The aim of the present study is to systematically review the literature to determine the average glenoid anthropometric parameters in the Indian population. Methods: A comprehensive literature search was conducted using preferred reporting items for systematic reviews and meta-analyses guidelines in the PubMed, EMBASE, Google Scholar, and Cochrane Library databases from the date of inception to May 2021. Any observational study conducted on the Indian population measuring the glenoid diameters, glenoid index, version, inclination, or any other glenoid measurements were included in the review. Results: A total of 38 studies were included in this review. The glenoid parameters were assessed on intact cadaveric scapulae in 33 studies, on 3DCT in three studies, and 2DCT in one study. The pooled average of glenoid dimensions are as the following- the superoinferior diameter or height was 34.65 mm, anteroposterior1 diameter or maximum width was 23.72 mm, anteroposterior2 diameter or maximum width of the upper part of the glenoid was 17.05 mm, the glenoid index was 67.88, and the glenoid version was 1.75-degree retroversion. Males were having a mean height of 3.65 mm and maximum width of 2.74 mm larger than the females. A subgroup analysis revealed no significant difference between different parts of India in glenoid parameters. Conclusion: The glenoid dimensions in the Indian population are smaller compared to the average European and American populations. The average glenoid maximum width of the Indian population is 1.3 mm smaller than the minimum glenoid baseplate size available in reverse shoulder arthroplasty. Glenoid components specific to the Indian market need to be designed to reduce glenoid failure attributable to the above findings. Level of evidence: III.

Serial 3D CT analysis of humeral head alignment in relation to glenoid correction and outcomes after total shoulder arthroplasty.

Background: Posterior humeral head (HH) subluxation after anatomic total shoulder arthroplasty (aTSA) is associated with worse outcomes, but it is unclear how corrective glenoid reaming correlates with HH alignment and whether HH alignment changes over time. Therefore, it was aimed to analyze the relationship between HH alignment and the scapula following aTSA to identify anatomic and surgical factors that contribute to realignment of the HH, glenoid loosening, and clinical outcomes. Methods: Three-dimensional scapulohumeral alignment was assessed on three-dimensionally reconstructed computed tomography scans of 23 patients: preoperative (T0), 2 years post-aTSA (T1), and ≥5 years post-aTSA (T2). Anterior-posterior (AP), superior-inferior (SI), and medial-lateral offset measures of the HH center to the scapula were referenced to the HH diameter (scapulohumeral subluxation index). Glenoid version and inclination were measured at T0 and T1. Central peg osteolysis, rotator cuff fatty infiltration, and vault perforation were assessed on two-dimensional computed tomography. Relative Constant Score at T2 measured clinical outcome. Results: Glenoid correction correlated strongly with AP and SI position of the HH (r = 0.733 and r = 0.797, respectively). Each degree of retroversion correction resulted in 0.9% AP scapulohumeral subluxation index offset change toward anterior. Each degree of inclination correction to superior resulted in a 1.0% offset change toward superior. A gradual postoperative proximal (mean difference [MD], -3%; P = .019), anterior (MD, 2%; P = .025), and medial (MD, 3 mm; P < .001) HH migration was observed. Asymmetric progressive rotator cuff fatty infiltration was associated with the direction of change in AP alignment over time (odds ratio, 2.04; P = .046), with progressive subscapularis fatty infiltration as the primary factor associated with gradual anterior HH translation (odds ratio, 15.61; P = .028). Gradual HH medialization was an indicator of glenoid components at risk for loosening (difference between medians, 4 mm; P = .003). Osteolysis around the central glenoid peg was influenced by overcorrection of glenoid version (MD, 7°; P = .038). Preoperative glenoid inclination was the sole anatomical or surgical factor predicting clinical outcome, as larger inferior inclination at T0 was associated with worse relative Constant Score at T2 (P = .016). Conclusion: Corrective glenoid reaming was an effective surgical technique to correct HH alignment in the AP and SI direction. Gradual anterior HH translation after aTSA was associated with progressive subscapularis fatty infiltration, and substantial HH medialization was an important indicator for potential glenoid loosening. While postoperative glenoid version and AP HH alignment were important for radiographic outcome, preoperative glenoid inclination predicted clinical outcome, as larger preoperative inferior inclination resulted in worse clinical scores.

Analysis and 3D correction of glenoid dysplasia with metal hemi-wedge base plate augment: short-term radiographic outcomes.

BACKGROUND: Glenoid defects can be addressed traditionally by asymmetric reaming or by bone-preserving correction to a more lateral joint line by bone or metal augmented baseplates in reverse shoulder arthroplasties. While there is more evidence in literature regarding the outcome and complications of Bony Increased Offset Reversed Shoulder Arthroplasty (BIO-RSA), there is minimal reported experience with the outcome after metal glenoid augments. The aim of this study was to determine whether a metal augment can correct the glenoid deformity in an anatomic manner. METHODS: Glenoid morphology and deformity were determined in 50 patients with Walch type B1, B2, D and Favard type E0-E3 glenoid defects using preoperative radiographic and computed tomography (CT) analysis. All patients received a preoperative planning CT with 3D planning, and measurements of glenoid inclination (in 3 planes proximal, middle, distal), reversed shoulder arthroplasty angle (RSA) and glenoid version were obtained. All patients had a pathologic inclination in the coronal or frontal planes of > 10°. Above the threshold of 10° pathological glenoid version or inclination metal hemi-augments of 10°, 20°, or 30° were used which allow an individual 360° augment positioning according to the patient glenoid deformity. RESULTS: The mean preoperative numbers of the glenoid version demonstrate that most glenoids were in retroversion and superior inclination. In total 2410° wedges, 1820° wedges and 8 30° wedges were used. In the majority of cases, the wedge was positioned posteriorly and/or cranially between 10:00 and 12:00 o'clock, which allows a correction in a 3D manner of the glenoid inclination and version. The mean RSA angle could be corrected from 22.76 ± 6.06 to 0.19° ± 2.7 (p < 0.0001). The highest retroversion of the glenoid is evidenced in the proximal section and it could be corrected from - 23.32° ± 4.56 to - 6.74° ± 7.75 (p < 0.0001) and in the middle section from - 18.93° ± 3.35 to - 7.66° ± 5.28 (p < 0.0001). A mean sphere bone overhang distance (SBOD) of 5.70 ± 2.04 mm was found in order to avoid or minimize relevant scapular notching. CONCLUSION: By using a new 360° metal-augmented baseplate, the preoperative pathological inclination and retroversion can be corrected without medialization of the joint line. Future clinical results will show whether this bone-preserving procedure improves also the clinical outcomes as compared to asymmetric medialized reaming or wedged BIO-RSA. LEVEL OF EVIDENCE: Level IV, Case series.

Difference analysis of the glenoid centerline between 3D preoperative planning and 3D printed prosthesis manipulation in total shoulder arthroplasty.

INTRODUCTION: Excessive version and inclination of the glenoid component during total shoulder arthroplasty can lead to glenohumeral instability, early loosening, and even failure. The orientation and position of the central pin determine the version and inclination of the glenoid component. The purpose of this study was to compare the differences in centerline position and orientation obtained using "3D preoperative planning based on the best-fit method for glenoid elements" and the surgeon's manipulation. MATERIALS AND METHODS: Twenty-nine CT images of glenohumeral osteoarthritis of the shoulder were reconstructed into a 3D model, and a 3D printer was used to create an in vitro model for the surgeon to drill the center pin. The 3D shoulder model was also used for 3D preoperative planning (3DPP) using the best-fit method for glenoid elements. The in vitro model was scanned and the version, inclination and center position were measured to compare with the 3DPP results. RESULTS: The respective mean inclinations (versions) of the surgeon and 3DPP were -2.63° ± 6.60 (2.87° ± 5.97) and -1.96° ± 4.24 (-3.21° ± 4.00), respectively. There was no significant difference in the inclination and version of the surgeon and 3DPP. For surgeons, the probability of the inclination and version being greater than 10° was 13.8% (4/29) and 10.3% (3/29), respectively. Compared to the 3DPP results, the surgeon's center position was shifted down an average of 1.63 mm. There was a significant difference in the center position of the surgeon and 3DPP (p < 0.05). CONCLUSION: The central pin drilled by surgeons using general instruments was significantly lower than those defined using 3D preoperative planning and standard central definitions. 3D preoperative planning prevents the version and inclination of the centerline from exceeding safe values (± 10°).

Quantitative statistical shape model-based analysis of humeral head migration, Part 2: Shoulder osteoarthritis.

We wanted to investigate the quantitative characteristics of humeral head migration (HHM) in shoulder osteoarthritis (OA) and their possible associations with scapular morphology. We quantified CT-scan-based-HHM in 122 patients with a combination of automated 3D scapulohumeral migration (=HHM with respect to the scapula) and glenohumeral migration (=HHM with respect to the glenoid) measurements. We divided OA patients in Group 1 (without HHM), Group 2a (anterior HHM) and Group 2b (posterior HHM). We reconstructed and measured the prearthropathy scapular anatomy with a statistical shape model technique. HHM primarily occurs in the axial plane in shoulder OA. We found "not-perfect" correlation between subluxation distance AP and scapulohumeral migration values (rs = 0.8, p < 0.001). Group 2b patients had a more expressed prearthropathy glenoid retroversion (13° vs. 7°, p < 0.001) and posterior glenoid translation (4 mm vs. 6 mm, p = 0.003) in comparison to Group 1. Binary logistic regression analysis indicated prearthropathy glenoid version as a significant predictor of HHM (χ² = 27, p < 0.001). Multivariate regression analysis showed that the pathologic version could explain 56% of subluxation distance-AP variance and 75% of the scapulohumeral migration variance (all p < 0.001). Herewith, every degree increase in pathologic glenoid retroversion was associated with an increase of 1% subluxation distance-AP, and scapulohumeral migration. The occurrence of posterior HHM is associated with prearthropathy glenoid retroversion and more posterior glenoid translation. The reported regression values of HHM in the function of the pathologic glenoid version could form a basis toward a more patient-specific correction of HHM.

Outcomes of Guided Personalized Surgery (GPS)-Navigated Reverse Polarity Total Shoulder Joint Replacement in a Low-Volume Hospital.

Introduction Reverse polarity shoulder arthroplasty (RSA) is an evolving surgery, and its indications have expanded over time. Apart from cuff tear arthropathy (CTA), it is recommended for complex proximal humerus fractures in the elderly, inflammatory arthritis, primary osteoarthritis in the elderly, and revision for failed hemiarthroplasty. Glenoid base plate placement and fixation are important to prevent complications, especially glenoid base plate loosening, dislocation, and scapular notching, and to improve longevity. Guided personalized surgery (GPS)-navigated RSA was devised to optimize the glenoid base plate position and fixation. Methodology A retrospective study was carried out in a low-volume district general hospital in England. All the patients who underwent GPS-navigated RSA were included. Their preoperative glenoid version, bone stock, glenoid base plate, and glenoid screw lengths were analysed. Preoperative and post-surgery patient-reported outcomes were gathered using the Oxford Shoulder Score (OSS) at six months and annually thereafter. Results Fourteen patients have undergone GPS-navigated RSA in our institute since 2018. Ten patients were female. All of them had a retroverted glenoid with a mean value of 13.6 degrees. Ten out of 14 patients had an augmented glenoid base plate. This included six eight-degree posterior augmentations, three 10-degree superior augmentations, and one extended cage peg. The follow-up period was six months to five years, depending on the date of surgery, and none of the patients dropped out of follow-up. The OSS revealed statistically significant improvement from preoperative values to six months postoperative, an improvement of 21.64±7.175. It also showed progressive improvement over time during postoperative follow-up, and the three-year mean was 47. The commonest complication was fractures, which happened in four cases. There were no infections or dislocations. Discussion Guided personalized surgery-navigated RSA was performed on selected patients at our institution when they were not suitable for conventional RSA due to distorted glenoid anatomy. Glenoid base plate positioning and fixation are important to optimize the outcome of RSA. Guided personalized surgery navigation is helpful in achieving optimum glenoid base placement, especially when the normal glenoid anatomy is distorted. There were no dislocations, glenoid base plate loosening, or scapular notching in the study group. There were four reported fractures, which was comparable with the published literature.

Humeral and Glenoid Version in Reverse Total Shoulder Arthroplasty: A Systematic Review.

There is increasing interest in reverse total shoulder arthroplasty (RTSA) as a reliable treatment for arthritic, rotator cuff deficient shoulders. Humeral and glenoid version are controversial parameters that can influence internal and external rotation, muscular forces, and implant stability as outcomes of RTSA. The aim of this study was to obtain an overview of the current knowledge on the effect of both humeral component version and glenoid component version and give recommendations on their most optimal degree for RTSA. A comprehensive quantitative review of the published literature on the effect of humeral version and glenoid version in RTSA was performed, to identify its influence on the range of movement, muscle forces, and intrinsic stability of the reverse prosthesis. Eleven studies were included: nine were biomechanical studies, one was a clinical-radiographic study, and one was an implant design consideration. Anterior stability can be improved by implanting the humeral component in neutral or with some anteversion. Glenoid component retroversion has been proven to reduce the likelihood of subluxation, while increasing ER and ROM at the same time. The study was conducted considering 5° anteversion; neutral; and 5°, 10°, and 20° retroversion of the glenoid component. Although a final opinion has not been yet expressed on the matter, the general consensus tends to agree on restoring 0° to 20° of retroversion of the humeral and glenoid component to yield the best outcomes.

Shoulder Osteoarthritis.

Glenohumeral osteoarthritis has proven to be a major contributor to shoulder joint pain and dysfunction in the elderly. There are several conditions about the shoulder that contribute to the development of glenohumeral osteoarthritis, which includes traumatic injuries, rotator cuff pathology, glenohumeral instability, glenoid dysplasia, and osteonecrosis. When glenohumeral osteoarthritis pain is refractory to conservative treatment, intra-articular injections and surgery can be performed. The radiologist should be aware of the varying types of shoulder arthroplasties, what preoperative findings influence that decision and the expected postoperative appearance of the differing components.

Glenoid Version Assessment When the CT Field of View Does Not Permit the Friedman Method: The Robertson Method.

Background: To improve spatial resolution, current clinical shoulder cross-sectional imaging studies reduce the field of view of the shoulder, excluding the medial scapula border and preventing glenoid version measurement according to the Friedman method. Purpose: To evaluate a method to accurately and reliably measure glenoid version on cross-sectional shoulder images when the medial scapula border is not included in the field of view, and to establish measurements equivalent to the Friedman method. Study Design: Controlled laboratory study. Methods: Sixty-five scapulae underwent computed tomography (CT) scanning with an optimal shoulder CT-positioning protocol. Glenoid version was measured on CT images of the full scapula using the Friedman method. We developed a measurement method (named the Robertson method) based on the glenoid vault version from partial scapula images, with a correction angle subtracted from the articular-surface-glenoid vault measurement. Comparison with the Friedman method defined the accuracy of the Robertson method. Three observers tested inter- and intraobserver reliability of the Robertson method. Accuracy was statistically evaluated with t tests and reliability with the intraclass correlation coefficient (ICC). Results: The statistical distribution of glenoid version was similar to published data,-0.5° ± 3° [mean ± SD]. The initial measurement using the Robertson method resulted in a more retroverted angle compared with the Friedman method, and a correction angle of 7° was then applied. After this adjustment, the difference between the 2 methods was nonsignificant (0.1° ± 4°; P > .65). Reliability of the Robertson method was excellent, as the interrater ICC was 0.77, the standard error of measurement (SEM) was 1.1° with P < .001. The intrarater ICC ranged between 0.84 and 0.92, the SEM ranged between 0.9° and 1.2° with P < .01. Conclusion: A validated glenoid version measurement method is now available for current clinical shoulder CT protocols that reliably create Friedman-equivalent values. Clinical Relevance: Friedman-equivalent values may be made from common clinical CTs of the shoulder and compared with prior and future Friedman measurements of the scapula.

The relationship of glenoid version and severity of glenoid bone loss in anterior shoulder instability patients: A retrospective cohort study.

Background/objective: The effect of glenoid version on the severity of glenoid bone loss is not completely understood, although the variation of glenoid version angles is considered to reflect the degree of glenoid bone loss in anterior shoulder instability cases. The objective of this retrospective case-control study is to determine the relationship of the glenoid version and the severity of glenoid bone loss in a group of previously documented recurrent anterior shoulder dislocation patients. Methods: We retrospectively collected magnetic resonance arthrogram (MRA) data from 72 patients with unidirectional recurrent anterior shoulder instability. The best-fit circle method was used to identify the percentage of glenoid bone loss. Measurements of glenoid labral, chondral, and bony versions were performed using the Friedman method. Results: Using univariate regression analysis, it was found that a retroversion angle of more than 4 degrees was associated with an increased risk ratio for the occurrence of a critical glenoid defect by approximately 5 times. Conclusions: 24 Univariate logistic regression analysis, used to determine the presence of a critical glenoid bone defect, showed that both the bony version angle and the number of previous dislocations were significantly associated with the extent of glenoid bone loss. A retroversion angle of more than 4 degrees was associated with an approximately five-fold increase in the odds ratio for the presence of a critical glenoid defect. Surgeons may use the value of the measured glenoid version in prediction the required version of the reconstructive treatment.

Glenoid version: the role of genetic and environmental factors on its variability. An MRI study on asymptomatic elderly twins.

BACKGROUND: Glenoid version is the most variable parameter of the shoulder joint. No authors investigated if intrinsic genetic factors or influences from extrinsic sources are responsible for its variability. AIM: We compared glenoid version between elderly monozygotic and dizygotic twins intending to separate the contributions of genetics from shared and unique environments. METHODS: Glenoid version of the dominant shoulder was assessed by MRI using Friedman's method in 30 pairs of elderly twins (16 monozygotic-14 dizygotic; mean age ± SD: 63.72 ± 3.37, 53-72). Heritability was estimated as twice the difference between the intraclass correlation coefficients for monozygotic and dizygotic pairs. The influence of shared environment was calculated as the difference between monozygotic correlation coefficient and the heritability index. According to job category, one way analysis of variance was used to estimate the differences between groups in the total sample and within zygosity groups. RESULTS: Glenoid version angle in monozygotic and dizygotic twins was -2° (SD: 2°) and -3° (SD: 3°), respectively (p = 0.334). Heritability index was 0.98, while the contributions of shared and unique environment were 0 and 0.02, respectively. According to working classes, no significant differences were found between the groups (p = 0.732, F = 0.31). CONCLUSIONS: Glenoid version is mainly genetically determined and only marginally influenced by environments.Level of evidence: III.

Variability and reliability of 2-dimensional vs. 3-dimensional glenoid version measurements with 3-dimensional preoperative planning software.

BACKGROUND: Preoperative planning for total shoulder arthroplasty (TSA) may change according to the measured degree of glenoid version. Both 2-dimensional (2D) and 3-dimensional (3D) computed tomographic (CT) scans are used to measure glenoid version, with no consensus on which method is more accurate. However, it is generally accepted that 3D measurements are more reliable, yet most 3D reconstruction software currently in clinical use have never been directly compared to 2D. The purpose of this study is to directly compare 2D and 3D glenoid version measurements and determine the differences between the two. METHODS: CT scans were performed preoperatively on 315 shoulders undergoing either anatomic or reverse TSA. 2D measurements of glenoid version were obtained manually using the Friedman method, whereas 3D measurements were obtained using the Equinoxe Planning Application (Exactech Inc.) 3D-reconstruction software. Negative version values indicate retroversion, whereas positive values indicate anteversion. Two observers collected the 2D measurements 2 separate times, and intra- and interobserver measurements were calculated. Groups were compared for variability using intraclass correlation coefficients (ICCs), and for differences in sample means using Student t tests. Additionally, samples were stratified by version value in order to better understand the potential sources of error between measurement techniques. RESULTS: For the 2D measurements, intraobserver variability indicated excellent reproducibility for both observer 1 (ICC = 0.928, 95% confidence interval [CI] 0.911-0.942) and observer 2 (ICC = 0.964, 95% CI 0.955-0.971). Interobserver variability measurements also indicated excellent reproducibility (ICC = 0.915, 95% CI 0.778-0.956). The overall 2D version measurement average (-4.9° ± 10.3°) was significantly less retroverted than the 3D measurement average (-8.4° ± 9.1°) (P < .001), with 3D measurements yielding a more retroverted value 73% of the time. When stratified on the basis of version value with outliers excluded, there was no significant difference in the distribution of high-error samples within the data. DISCUSSION: There was excellent reproducibility between the 2 observers in terms of both intra- and interobserver variability. The 3D measurement techniques were significantly more likely to return a more retroverted measurement, and high-error samples were evenly distributed throughout the data, indicating that there were no discernable trends in the degree of error observed. Shoulder surgeons should be aware that different glenoid version measurement strategies can yield different version measurements, as these can affect preoperative planning and surgeon decision making.

Variability in total shoulder arthroplasty planning software compared to a control CT-derived 3D printed scapula.

BACKGROUND: Two techniques exist from which all 3D preoperative planning software for total shoulder arthroplasty are based. One technique is based on measurements constructed on the mid-glenoid and scapular landmarks (Landmark). The second is an automated system using a best-fit sphere technique (Automated). The purpose was to compare glenoid measurements from the two techniques against a control computed tomography-derived 3D printed scapula. METHODS: Computed tomography scans of osteoarthritic shoulders of 20 patients undergoing primary total shoulder arthroplasty were analyzed with both 3D planning software techniques. Measurements from a 3D printed scapula (Scapula) from the true 3D computed tomography scan served as controls. Glenoid version and inclination measurements from each group were blinded and reviewed. RESULTS: In 65% (Automated) and 45% (Landmark) of cases, either inclination or version varied by 5° or more versus 3D printed scapula. Significant variability in version differences compared to the scapula group existed (p = 0.007). Glenoid version from the Scapula = 13.0° ± 10.6°, Automated = 15.0° ± 13.9°, and Landmark = 12.2° ± 7.8°. Inclination from Scapula = 5.4° ± 7.9°, Automated = 6.1° ± 12.6°, and Landmark = 6.2° ± 9.1°. DISCUSSION: A high percentage of cases showed discrepancies in glenoid inclination and version values from both techniques. Surgeons should be aware that regardless of software technique, there is variability compared to measurements from a control 3D computed tomography printed scapula.

Three Dimensional Anthropometric Analysis of Glenoid Anatomy in Normal Indian Population.

BACKGROUND: Shoulder unlike any other joint has a wide range of mobility and is important in day to day activities. Different ethnic groups vary in skeletal anatomy and anthropometry. Most of our knowledge on the shoulder-anatomy, surgical technique and prosthesis designs is based on western literature. There are few studies on the Indian population. Our aim is to study the anthropometry of glenoid based on 3D CT scan of the shoulder. Our objectives are to calculate glenoid height, width, version, inclination, analyse the data for differences between male and female, compare data with similar studies in India and other countries and study the impact on shoulder arthroplasty implant size. MATERIALS AND METHODS: 100 CT scans (male/female-50/50) of the Indian population are studied from our database. Glenoid measurements are calculated and analyzed. RESULTS: The mean value of glenoid height is 32.9 ± 3.2 mm (27.6-41.7 mm), width 23.4 ± 2.62 mm (19.1-30.9 mm), version 0.07 ± 5.38° (- 11° to + 10.85°) and inclination 6.68 ± 5.49° (- 9.91° to + 20.75°). In our study glenoid is retroverted, superiorly inclined and height is more than width. The height and width are less than French and Americans but slightly more than the Japanese population. CONCLUSION: There are significant differences in Indian glenoid measurements compared to other countries. Even the smallest size of shoulder arthroplasty glenoid component currently available in India is larger than the mean glenoid size of our study. As shoulder replacement surgeries are rising in India, we may have to bring changes in the implant design and surgical technique to suit our population.