Glenoid Version Research Articles

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.

Postoperative acromiohumeral interval affects shoulder range of motions following reverse total shoulder arthroplasty

Reverse total shoulder arthroplasty (RTSA) improves function and reduces pain for patients with complex shoulder problems. However, there is a lack of literature regarding the association of radiographic parameters on clinical outcomes after RTSA. The aim of this study was to analyze various radiographic parameters that may be predictive of clinical outcomes after RTSA. A total of 55 patients treated with RTSA were enrolled. Shoulder radiographic parameters were used for measurement of critical shoulder angle, acromial index, acromiohumeral interval, deltoid lever arm, acromial angulation, glenoid version, and acromial height. Preoperative and postoperative clinical outcomes were evaluated at a minimum 2-year follow-up. An analysis of correlations between radiographic parameters and clinical outcomes was then performed. A significant change in critical shoulder angle, acromiohumeral interval, and deltoid lever arm was observed between preoperative and postoperative radiographic measurements. A significant improvement was observed in all clinical outcomes and range of motions from preoperative to postoperative (all p < 0.001). A negative correlation of postoperative acromiohumeral interval with forward flexion (r = − 0.270; p = 0.046), external rotation (r = − 0.421; p = 0.001), and internal rotation (r = 0.275; p = 0.042) was observed at final follow-up. In addition, postoperative acromiohumeral interval less than 29 mm had an 86% positive predictive value of obtaining 130° of forward flexion and 45° of external rotation. It was found that postoperative acromiohumeral interval showed an association with active range of motion in patients who underwent RTSA. In particular, excessive distalization reduced forward flexion and external rotation motion of the shoulder in patients treated with RTSA.

Morphology of Humeral Head and Glenoid in Normal Shoulder of Indonesian Population.

Shoulder prostheses designed and used around the world may not fit an Asian shoulder. Normal shoulder morphology in Asian population had been reported, ie, Chinese, Indian, Japanese, and Thai populations, but no data from the Indonesian population. The aim of this study was to evaluate the three-dimensional (3D) morphology of the glenohumeral joint in the normal Indonesian population, identify its normal values, and compare them with those of other populations in the literature. Images for analysis were computed tomography (CT) scans of 85 normal shoulders from 71 patients who had CT scans for another diagnosis. Morphometry of the humeral head and glenoid were measured using 3D reconstruction. Gender differences and correlations between age, height, and glenohumeral morphometry were evaluated. Indonesians' glenohumeral morphometry was compared with those of other populations in the literature. In the normal Indonesian population, the mean of humeral head inclination (HHI), height (HHH), diameter in sagittal plane (DS), diameter in frontal plane (DF), radius of curvature in sagittal plane (RS), and radius of curvature in frontal plane (RF) were 134.1°, 15.6mm, 39.3mm, 41.3mm, 20.4mm, and 21.4mm, respectively. The glenoid height (GH), upper width (GUW), lower width (GLW), inclination (GI), and version (GV) mean values were 34.2mm, 18.4mm, 24.5mm, 74.0mm, and 12.3mm, respectively. There was a significant difference in HHH, DS, DF, RS, RF, GH, GUW, GLW between males and females. Except for HHI and GI, glenohumeral morphometry was correlated with patient height. Age was not correlated with any glenohumeral morphometry. In the Indonesian population, males had a larger humeral head and glenoid than females, and the size of the humeral head and glenoid was correlated to body height. Indonesians' humeral head and glenoid sizes were smaller than those of Western populations, but close to those of other Asian populations.

COMPUTER TOMOGRAPHIC ANALYSIS OF THE GLENOID COMPONENT IN REVERSE SHOULDER ARTHROPLASTY

The positioning of the glTenoid component in RSA ( Reverse Shoulder Arthroplasty) is one of the factors determining implant survival and postoperative outcomes. Therefore, accurate determination of the glenoid version and inclination in RSA is essential for the surgeon - preoperatively to plan his work and postoperatively - to assess the outcome. Excessive retroversion and superior inclination are prerequisites for unsatisfactory results and are associated with a high frequency of revisions. The glenoid inclination is often described as the angle between the glenoid fossa line and the suprascapular reference line. The study included a 2-year follow-up of patients with reverse shoulder arthroplasty in the Department of Orthopedics. The analysis is based on pre / postoperative CT and three-dimensional reconstruction using Medi Cad software. A comparative analysis was made with the results obtained by X-ray examination. The results showed a high incidence of superior inclination of native glenoid fossae. The obtained ß-inclination angle averaged 13.8 °, and the difference in this radiographically measured parameter was 7.3 °. CT analysis preoperatively significantly improves the position of the glenoid component and avoids the superior inclination of the baseplate of the prosthesis.

Comparison of computed tomography and 3D magnetic resonance imaging in evaluating glenohumeral instability bone loss.

To determine whether the addition of 3-dimensional (3D) magnetic resonance imaging (MRI) to standard MRI sequences is comparable to 3D computed tomographic (CT) scan evaluation of glenoid and humeral bone loss in glenohumeral instability. Eighteen patients who presented with glenohumeral instability were prospectively enrolled and received both MRI and CT within 1 week of each other. The MRI included an additional sequence (volumetric interpolated breath-hold examination [VIBE]) that underwent postprocessing for reformations. The addition of a VIBE protocol, on average, is an additional 4-4.5 minutes in the scanner. CT data also underwent 3D postprocessing, and therefore each patient had 4 imaging modalities (2D CT, 2D MRI, 3D CT reformats, and 3D MRI reformats). Each sequence underwent the following measurements from 2 separate reviewers: glenoid defect, glenoid defect percentage, humeral defect, humeral defect percentage, and evaluation of glenoid track and version. Paired t tests were used to assess differences between imaging modalities and χ2 for glenoid track. Intra- and interobserver reliability were evaluated. Bland-Altman tests were also performed to assess the agreement between CT and MRI. In addition, we determined the cost of each imaging modality at our institution. 3D MRI measurements for glenoid and humeral bone loss measurements were comparable to 3D CT (Table1). There were no significant differences for glenoid defect size and percentage, or humeral defect size and percentage (P>.05) (Table2). Bland-Altman analysis demonstrated strong agreement, with small measurement errors for 3D CT and 3D MRI percentage glenoid bone loss. There was also no difference in evaluation for determining on vs. off track between any of the imaging modalities. Inter- and intrarater reliability was good to excellent for all CT and MRI measurements (r ≥ 0.7). 3D MRI measurements for bone loss in glenohumeral instability through use of VIBE sequence were equivalent to 3D CT. At our institution, undergoing MRI with 3D reconstruction was 1.67 times cheaper than MRI and CT with 3D reconstructions. 3D MRI may be a useful adjuvant to standard MRI sequences to allow concurrent soft tissue and accurate assessment of glenoid and humeral bone loss in glenohumeral instability.

Version reckoning of variant glenoid levels: a radiological study on dry human scapulae

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; Preoperative glenoid version measurement can guide base plate implantation and directing screws positioning. Glenoid vault depth affects guide-wire insertion with accurate inclinations towards maximum bone stock. No consensus exists regards the precise glenoid level for version assessment, whether at midaxial or coracoid tip level, and if those values are identical or not. Additionally, there is not much data in literature concerning the deepest point of glenoid vault and its proximity to anterior and inferior glenoid surfaces. Thus, we aimed in this study to report glenoid version values at all levels utilizing two different methodologies (Freidman method, vault version method). Additionally, detecting deepest vault point and how much distant from anterior and inferior glenoid aspects.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Sixty dry, unpaired scapulae were scanned with 1.25mm-thick slices. Version was measured at all levels and compared. Axial and coronal slices with greatest vault depth was determined and distance from anterior and inferior glenoid rims were determined.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Version method showed significant difference in version at coracoid tip and midaxial levels (p&amp;lt;0.001). Mean versions were 18.2±10.6º and 8.9±6.8º respectively. Also, significant difference was noted between version of upper, middle, and lower thirds, except between middle and lower thirds. A significant difference was evident between both methodologies on comparing version at coracoid tip level (p&amp;lt;0.001).&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="Default"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Glenoid version at coracoid tip and midaxial levels are not the same. Correlation of preoperative version values with intraoperative situations might be studied in future studies.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt; &lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Anatomic total shoulder glenoid component inclination affects glenohumeral kinetics during abduction: a cadaveric study.

Although typically favorable in outcome, anatomic total shoulder arthroplasty (aTSA) can require long-term revision. The most common cause for revision is glenoid loosening, which may result from eccentric cyclic forces and joint translations. "Rocking" of the glenoid component may be exacerbated by the joint geometry, such as glenoid inclination and version. Restoration of premorbid glenoid inclination may be preferable, although laboratory and computational models indicate that both superior inclination and inferior inclination have benefits. This discrepancy may arise because previous studies were limited by a lack of physiological conditions to test inclination. Therefore, a cadaveric shoulder simulator with 3-dimensional human motion was used to study joint contact and muscle forces with isolated changes in glenoid inclination. Eight human cadaveric shoulders were tested before and after aTSA. Scapular-plane abduction kinematics from human subjects were used to drive a cadaveric shoulder simulator with 3-dimensional scapulothoracic and glenohumeral motion. Glenoid inclination was varied from -10° to +20°, whereas compressive, superior-inferior shear, and anterior-posterior shear forces were collected with a 6-df load cell during motion. Outputs also included muscle forces of the deltoid and rotator cuff. Data were evaluated with statistical parametric mapping repeated-measures analysis of variance and t tests. Inferior glenoid inclination (-10°) reduced both compressive and superior-inferior shear forces vs. neutral 0° inclination by up to 40%, and even more when compared with superior inclination (P<.001). Superior inclinations (+10° and +20°) tended to increase deltoid and rotator cuff forces vs. neutral 0° inclination or inferior inclination, on the order of 20%-40% (P≤.045). All force metrics except anterior-posterior shear were lowest for inferior inclination. Most aTSA muscle forces for neutral 0° inclination were not significantly different from native shoulders and decreased 45% and 15% in the posterior deltoid and supraspinatus, respectively (P≤.003). Joint translations were similar to prior reports in aTSA patients and did not differ between any inclinations or compared with native shoulders. Joint reaction forces were similar to those observed in human subjects with instrumented aTSA implants, providing confidence in the relative magnitude of our results. Inferior inclination reduces overall forces in the shoulder. Superior inclinations increase the muscle effort required for the shoulder to achieve similar motion, thus increasing the forces exerted on the glenoid component. These results suggest that a preference toward aTSA glenoid components in inferior inclination may reduce the likelihood of glenoid loosening by reducing excessive muscle and joint contact forces.

THE RESULTS OF ARTHROSCOPIC RELEASE WITH TENDON TRANSFERS IN CASES OF B.P.B.P WITH GLENOHUMERAL DYSPLASIA

Background: Internal rotation deformity due to brachial plexus birth palsy frequently lead to glenohumeral deformity . Our surgical approach to treat these contractures relies on arthroscopic release and tendon transfer of latissimus dorsi muscle for young children . We report the results for twenty children followed for a minimum of two years after such treatment Patients and methods: This study was done in the Orthopedic department, Sohag University Hospitals including all patients with brachial plexus birth palsy with internal rotation contracure of the shoulder. Twenty children with a mean age of 4 years (between 2 and 6 years old) underwent arthroscopic contracture release and tendon transfer of latissimus dorsi muscle as a primary procedure.Passive and active external rotation, internal rotation, and elevation were measured for all patients pre and postoperatively. Modified mallet score and active movement score was measured pre and postoperatively. Magnetic resonance imaging was performed preoperatively and postoperatively to evaluate glenoid version and head sublaxation. Results: At the time of follow-up, the mean passive external rotation was increased by 67° (p &lt; 0.005) in the children with a successful arthroscopic release and tendon transfer. The mean active elevation increased by 12°. Internal rotation was not measured consistently preoperatively, but when it had been it was found to have decreased substantially postoperatively. Mean glenoid version improved from -33° to -7° following soft-tissue releases and The percentage of the humeral head anterior to the middle of the glenoid improved from 8% to 43%. While the average duration of clinical and radiographic follow-up was twenty-four months, improvements in both shoulder motion and glenohumeral joint morphology were seen early and were maintained during the follow up period. Conclusion: In children with internal rotation contracture, arthroscopic release and tendon transfer effectively restores nearly normal passive external rotation and a centered glenohumeral joint at the time of surgery. In most of these children, external rotation strength is sufficient to maintain this range of motion and to improve glenoid development when preoperative deformity was present. Improvement in active elevation was minimal. All children have a loss of internal rotation, which is moderate in most of them.

Prospective Evaluation of Posterior Glenoid Bone Loss After First-time and Recurrent Posterior Glenohumeral Instability Events

Background: Although posterior glenohumeral instability is becoming an increasingly recognized cause of shoulder pain, the role of posterior glenoid bone loss on outcomes remains incompletely understood. Purposes: To prospectively determine the amount of bone loss associated with posterior instability events and to determine predisposing factors based on preinstability imaging. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 1428 shoulders were evaluated prospectively for ≥4 years. At baseline, a subjective history of shoulder instability was ascertained for each patient, and bilateral noncontrast magnetic resonance imaging (MRI) scans of the shoulders were obtained regardless of any reported history of shoulder instability. The cohort was prospectively followed during the study period, and those who were diagnosed with posterior glenohumeral instability were identified. Postinjury MRI scans were obtained and compared with the screening MRI scans. Glenoid version, perfect-circle-based bone loss was measured for each patient's pre- and postinjury MRI scans using previously described methods. Results: Of the 1428 shoulders that were prospectively followed, 10 shoulders sustained a first-time posterior instability event and 3 shoulders sustained a recurrent posterior instability event. At baseline, 11 of 13 shoulders had some amount of glenoid dysplasia and/or bone loss. The change in glenoid bone loss was 5.4% along the axis of greatest loss (95% CI, 3.8%-7.0%; P = .009), 4.4% at the glenoid equator (95% CI, 2.7%-6.2%; P = .016), and 4.2% of total glenoid area (95% CI, 2.9%-5.3%; P = .002). Recurrent glenoid instability was associated with a greater amount of absolute bone loss along the axis of greatest loss compared with first-time instability (recurrent: 16.8% ± 1.1%; 95% CI, 14.6%-18.9%; first-time: 10.0% ± 1.5%; 95% CI, 7.0%-13.0%; P = .005). Baseline glenoid retroversion ≥10° was associated with a significantly greater percentage of bone loss along the axis of greatest loss (≥10° of retroversion: 13.5% ± 2.0%; 95% CI, 9.6%-17.4%; <10° of retroversion: 8.5% ± 0.8%; 95% CI, 7.0%-10.0%; P = .045). Conclusions: Posterior glenohumeral instability events were associated with glenoid bone loss of 5%. The amount of glenoid bone loss after a recurrent posterior glenohumeral instability event was greater than that after first-time instability. Glenoid retroversion ≥10° was associated with a greater amount of posterior glenoid bone loss after a posterior instability event.

Glenoid Morphology and Related Parameters in Turkish Society.

IntroductionGlenoid morphology may vary in different ethnic groups. Detection of these differences may be important in preoperative planning, especially in reverse shoulder arthroplasty. In this study, we investigated the mean glenoid size and retroversion in Turkish society and their relationship with the dominant side, gender, height, weight, and body mass index (BMI).Materials and methodsBetween 2019 and 2021, 102 shoulders of 51 patients (24 females/27 males, 51 left/51 right) who were included in shoulder joint imaging during thorax CT scanning were examined. Those with glenoid fracture, arthrosis, shoulder surgery or deformity, or younger than 18 years of age were not included in the study. The mean age was 41.69 (range: 18-73) years. Glenoid anterior-posterior diameter (D) and glenoid version (GV) were measured in axial slices, and glenoid height (H) was measured in coronal slices. The correlation of these parameters with gender, height, weight, and dominant side was examined.ResultsMean D was 25.79±4.44 mm, mean H was 29.08±4.08 mm, and mean GV was -0.99°±0.92°. The mean height of the patients was 162±16.23 cm and the mean weight was 71.9±15.36 kg. The glenoid diameter and height were smaller in females, however, no statistically significant difference was found in the glenoid version (p<0.01, p<0.01, and p=0.92). The glenoid on the dominant side was statistically significantly more retroverted, whereas D and H were not associated with dominance (p<0.01, p=0.9, and p=0.98). It was found that the glenoid sizes were very highly correlated with the patient's height, and it was highly correlated with the patient's weight (p<0.01 and p<0.01). On the other hand, height and weight were not correlated with the glenoid version (p=0.47 and p=0.81, respectively). There was no statistically significant relationship between BMI and glenoid sizes and glenoid version (p=0.14 and p=0.46, respectively).ConclusionsFemales in Turkish society had small glenoid sizes. Male gender, height, and weight were positively correlated with large glenoids. The glenoid was more retroverted on the dominant side. These findings should be considered in preoperative planning in Turkish society.

The Effect of Glenoid Version on Glenohumeral Instability.

In recent years, an appreciation for the dynamic relationship between glenoid and humeral-sided bone loss and its importance to the pathomechanics of glenohumeral instability has substantially affected modern treatment algorithms. However, comparatively less attention has been paid to the influence of glenoid version on glenohumeral instability. Limited biomechanical data suggest that alterations in glenoid version may affect the forces necessary to destabilize the glenohumeral joint. However, this phenomenon has not been consistently corroborated by the results of clinical studies. Although increased glenoid retroversion may represent an independent risk factor for posterior glenohumeral instability, this relationship has not been reliably observed in the setting of anterior glenohumeral instability. Similarly, the effect of glenoid version on the failure rates of surgical stabilization procedures remains poorly understood.

Description and Validation of the Anterior Glenoid Angle: A Novel MRI-Based Measure of Glenoid Morphologic Features and Version.

The goal of this study was to establish a normal value for, and evaluate the reliability of, a new measurement of glenoid morphologic features using magnetic resonance imaging: the anterior glenoid angle. A total of 90 magnetic resonance imaging scans of patients without shoulder arthritis were reviewed. The anterior glenoid angle of each glenoid was measured by 4 blinded physicians. The images were randomized and measured again. Finally, the Friedman angle was measured on the same images for reference. Descriptive statistics and inter- and intraclass correlation coefficients were calculated. The mean anterior glenoid angle was 60.4°±3.6°. Of the measured values, 77% were between 56° and 64°. Intraobserver reliability was very good to excellent in single measure (range, 0.763-0.901) and mean measure (range, 0.865-0.948) comparisons. Interobserver reliability was very good to excellent in both single measure (0.769) and mean measure (0.964) comparisons. The mean Friedman angle was 10.2°. Correlation between the anterior glenoid angle and Friedman angle ranged from a moderate negative (-0.496) to a strong negative correlation (-0.711) among the observers. The mean anterior glenoid angle measured via magnetic resonance imaging scan was 60.4° in normal shoulders, and more than 75% of the values were within 4° of the mean. The anterior glenoid angle has excellent inter- and intrarater reliability without using computed tomography scan or including the entire scapula in the field of view. The anterior glenoid angle has a good to very good negative correlation with the Friedman angle because decreasing anterior glenoid angles indicate increasing retroversion. [Orthopedics. 2022;45(6):361-366.].

Poster 183: Acromial Morphology Predicts Glenoid Bone Loss in Patients with Posterior Glenohumeral Instability

Objectives:The relationship between acromial morphology and glenohumeral instability is not well understood. It is unknown whether a flatter acromion predisposes a nonarthritic shoulder to increased posterior glenoid bone loss (GBL). The purpose of this study was to determine whether acromial morphology influences the extent or pattern of posterior glenoid bone loss in a cohort of patients with posterior glenohumeral instability.Methods:A comprehensive review of case logs between two academic institutions was performed to identify patients treated for primary posterior glenohumeral instability. MRI and/or CT scans were examined by two independent reviewers and the following measurements were obtained: total area glenoid bone loss (GBL) using the perfect circle technique, glenoid version, obliquity of GBL relative to the long axis of the glenoid, arc of GBL, acromial tilt, posterior acromial height (PAH), and anterior/posterior acromial coverage. The primary outcome was the association between acromial morphology parameters and glenoid bone loss.Results:A total of 89 shoulders with primary posterior glenohumeral instability were included. The mean age was 28.3 years (range 18-49), and male:female ratio was 11:1. Fifty-nine patients had measurable posterior glenoid bone loss and 30 patients had posterior labral tears without bone loss. Linear regression analysis revealed a significant negative correlation between acromial tilt and posterior GBL (R2= 0.09, p=0.005), a positive correlation between PAH and posterior GBL (R2= 0.04, p=0.046), and a negative correlation between posterior acromial coverage and posterior GBL (R2= 0.03, p=0.005). Increasing PAH and decreasing posterior acromial coverage were associated with a more superior extent of GBL (R2= 0.1, p=0.044 and 0.024, respectively). Subgroup analysis stratified by total area of GBL demonstrated that the area of posterior glenoid bone loss increases as the acromial tilt decreases.Conclusions:A flatter, higher acromion with less posterior coverage relative to the center of the glenoid is associated with increased posterior glenoid bone loss in patients with posterior glenohumeral instability.Table 1.

Paper 06: The Natural History of Nonoperative Treatment of Posterior Instability in a High Demand Population

Objectives:Nonoperative management of posterior shoulder instability is common, however there is limited data available to assess the pathomorphology of nonoperative management. The purpose of this study is to evaluate glenohumeral pathomorphology in shoulders with posterior glenohumeral instability treated nonoperatively.Methods:We conducted a retrospective review of a consecutive series of patient with isolated posterior shoulder instability defined as an isolated posterior labral tear with a corresponding positive Jerk or Kim test. Patients were excluded if they had prior shoulder surgery or absence of a Jerk or Kim test. Non-operative management was defined as a trial of formal physical therapy pursuit of nonsurgical modalities for a minimum 6 months. Patients who underwent non-operative management and subsequently had a repeat MRI of the initially injured shoulder were identified, and the two studies were compared to evaluate for changes in glenoid bone loss, glenoid morphology, cartilage injuries, and the presence of concurrent pathology. Our primary outcome was glenoid changes associated with failure of non-operative management, which was defined as reoperation and/or medical separation from the military due to the injured shoulder. Secondary outcomes included evaluation of potential risk factors for failure of non-operative management including glenoid bone loss, glenoid version, and posterior humeral head subluxation. Continuous variables were compared with student’s t-test or Fisher exact test when appropriate. Categorical variables were analyzed using Chi-squared. Multivariable regression analysis was used to evaluate risk factors for failure.Results:42/90 (46.7%) patients failed a 6-month trial of nonoperative management after being diagnosed with posterior glenohumeral instability and went onto receive an arthroscopic stabilization procedure. The failure group demonstrated a significantly greater humeral head subluxation ratio than the cohort of patients who survived nonoperative management (0.65 ± 0.2 vs 0.62 ± 0.2; p = 0.0375). Of those who failed nonoperative management only 17 had repeat MRI’s for comparison with initial MRI’s, which revealed a significantly greater increase in glenoid bone loss (6.54 ± 1.59 vs 2.68 ±1.71; p = 0.00274). The mean time from index MRI and repeat MRI was 488 days (95% CI 317 to 658).Conclusions:In patients that underwent 6-months of nonoperative management for isolated posterior glenohumeral instability, failure occurred approximately 47% of the time and was associated with a greater posterior humeral head subluxation ratio on index MRI than those who did not fail. Additionally, those who had repeat MRI on average 1.3 years later demonstrated greater glenoid bone loss when compared to the index MRI.

Poster 133: Validation of 3D MRI in Glenohumeral Instability Evaluation of Glenoid and Humeral Bone Loss including Glenoid Track Compared to CT Scan

Objectives:The objective of our study is to determine whether the addition of 3-dimensional (3D) MRI to standard MRI sequences is comparable to 3D CT scan evaluation of glenoid and humeral bone loss in glenohumeral instability. There is increasing understanding of the importance of the glenoid, as well as humeral bone loss in outcomes and surgical decision making in patients with shoulder instability. Although magnetic resonance imaging (MRI) is performed as standard of care for soft tissue evaluation of shoulder instability, CT scan remains the gold standard in bony measurements. Standard MRI evaluation has been shown to inaccurately measure bone loss. However, additional CT scans result in increased financial, time, and ionizing radiation cost to the patient.Methods:Eighteen patients who presented with glenohumeral instability were prospectively enrolled and received both MRI and CT within 1 week of each other. The MRI included an additional sequence (VIBE) which underwent post-processing for reformations (Figure 1a). The addition of a VIBE protocol, on average is an addition 4 to 4.5minutes in the scanner. CT data also underwent 3D post-processing (Figure 1b) and therefore each patient had four imaging modalities (2D CT, 2D MRI, 3D CT reformats, and 3D MRI reformats). Each sequence underwent the following measurements from two separate reviewers: glenoid defect, glenoid defect percent, humeral defect, humeral defect percentage (Figure 2a and 2b), and evaluation of glenoid track and version. Paired t-tests were used to assess differences between imaging modalities and chi squared for glenoid track. Intra-observer and inter-observer reliability were evaluated. Bland-Altman tests were also performed to assess the agreement between CT and MRI. In addition, we determined cost of each imaging modality at our single institution.Results:3D MRI measurements for glenoid and humeral bone loss measurements were comparable to 3D CT (Table 1). There were no significant differences for glenoid defect size and percentage, or humeral defect size and percentage (P>0.05) (Table 2). Bland-Altman analysis demonstrated strong agreement with small measurement errors for 3D CT and 3D MRI percentage glenoid bone loss. There was also no difference in evaluation for determining on vs off track between any of the imaging modalities. Inter- and intra-rater reliability was good to excellent for all CT and MRI measurements (r >= 0.7).Conclusions:3D MRI measurements for bone loss in glenohumeral instability through utilization of VIBE sequence were equivalent to 3D CT. At our institution, the costs of MRI with 3D reconstruction was 1.67x cheaper than MRI and CT with 3D reconstructions. 3D MRI may be a useful adjuvant to standard MRI sequences to allow concurrent soft tissue and accurate assessment of glenoid and humeral bone loss in glenohumeral instability.Figure 1a.(3D MRI glenoid reformation) and lb (3D CT glenoid reformation): Glenoid measurement for 3D reconstruction of MRI and CT using sagittal en face of the glenoid. A circle was placed over the inferior portion of the glenoid using margins as a guide for the circle. The glenoid height line (blue) runs from the supraglenoid tubercle to the medial aspect of the inferior base. Glenoid bone loss size (orange) and circle diameter (green) was quantified with glenoid height line marking the center of the circle. Percent glenoid bone loss was determined as [(glenoid bone loss size/circle diameter)* 100]. Glenoid track was determined through equation [(0.83 * circle diameter) - glenoid bone loss size]Figure 2a.(2D CT) and 2b (3D CT): 2a: Measurement of Hill Sachs maximal defect on axial 2D CT recorded in mm. 2b: Measurement of humeral defect percentage from the 3D reformats using sagittal projection with best fit circle. A line (blue) was placed to determine maximal humeral head height (A) then perpendicular line (green) to measure residual humeral head (B) and therefore bone defect (A-B)(orange). Percent bone loss was determined through [(A-B)/A)*100]Table 1:Mean 2D and 3D CT and MRI measurementsTable 2:Paired t-test Glenoid and Humeral Bone Loss Measurements.

Statistical shape modeling-based reconstruction eliminates the need for full scapular computed tomography scan data in preoperative total shoulder arthroplasty planning

BackgroundPreoperative total shoulder arthroplasty (TSA) planning tools use a three-dimensional (3D) model of the full scapula based on computed tomography (CT) images with a scan length covering the complete scapula with a given radiation exposure for patients. The aim of this study is to investigate whether full scapular models can be reconstructed from partial CT data. MethodsIn this retrospective cohort study, bone models representing 5 scan lengths with decreasing levels of scapular coverage (level 1-5) were created. All the models were reconstructed with a validated statistical shape model (SSM) allowing automatic 3D measurements of glenoid version, inclination, scapular offset, and center point position. Radiation exposure between 2 patient groups (group 1 = corresponding to L1, group 2 = complete scapula) was compared. ResultsIn terms of inclination and version, we found a mean absolute difference between the complete model and the different partial scan models of 0.5° (SD 0.4°). The maximum difference was 3° for inclination and 2° for version. For scapular offset and center point position, the mean difference was 0 mm (max 1 mm). The mean radiation exposure was 4 mSv (SD 2 mSv) for group 1 and 13 mSv (SD 6 mSv) for group 2 (P = .009). ConclusionAn SSM-based reconstruction technique can accurately reconstruct complete scapular bone models based on partial CT scan data. Incorporation of an SSM-based reconstruction technique in software tools for preoperative TSA planning would lead to decreased radiation exposure (9 mSv) for patients without influencing its accuracy.

3D-MRI versus 3D-CT in the evaluation of glenoid deformity in glenohumeral arthritis using Dixon 3D FLASH sequence.

To compare MRI with 3D reconstructions and 3D-CT with respect to assessment of glenoid wear in osteoarthritic shoulders. 3D reconstructions were generated for CT and MR (utilizing the Dixon technique) imaging performed on 29 osteoarthritic shoulders. Two reviewers independently performed glenoid morphometric measurements and evaluated glenoid erosion. Mean differences between the two modalities were calculated. Inter-observer agreement was calculated using kappa coefficient. The combined mean absolute difference (bias) in glenoid version between 3D-CT and 3D-MRI was 2.7° ± 1.6° (range 0.15-7.85, P value = 0.7). The combined mean absolute difference in glenoid inclination between 3D-CT and 3D-MRI was 6.8° ± 4.1° (range 0.8°-15.75°, P value = 0.17). No significant inter-reader variation in glenoid version and inclination measurements on 3D-CT and 3D-MRI was found (P > 0.05). The inter-reader reliability for both CT and MRI was high for Walch grading of glenoid bone loss (κ = 1, κ = 0.81, respectively). 3D-MRI is comparable to 3D-CT with respect to axial glenoid bone loss, as measured by glenoid version. However, for coronal bone loss estimation, measured by glenoid inclination, 3D-CT remains the gold standard. Thus, 3D-MR can be used as an alternative for preoperative assessment of glenoid version in arthritic shoulders.

Reverse shoulder arthroplasty with metallic augments to preserve bone and restore joint line in patients with glenoid bone loss

BackgroundGlenoid bone loss poses significant challenges for reverse shoulder arthroplasty. In these patients, excess reaming can lead to further bone loss and medialization of the joint line. Metallic augments have been described as a technique for addressing this issue. However, there are currently no studies evaluating the effect of metallic augments on anatomic outcomes. This study evaluates the effect of metallic augments on the glenohumeral joint line and bone preservation. We hypothesize that metallic augments can preserve bone while preventing further medialization of the joint line in patients with preoperative glenoid bone loss. MethodsA prospective single-center, 2-surgeon consecutive case series was evaluated with postoperative computed tomography scans. Three-dimensional reconstruction was used to create models of the scapula and humerus. Comparisons were made with preoperative computed tomography scans using volumetric analysis to evaluate bone loss. The base of the coracoid was used as a constant landmark to assess the joint line position and, by proxy, the center of rotation. Further evaluation of the glenoid version and inclination was measured on the reconstructed models through standardized techniques. ResultsFifteen patients (16 implants) underwent preoperative planning and reverse shoulder arthroplasty with metallic augments from January 1, 2018, to January 1, 2021. The mean follow-up time was 13.1 months. Analysis revealed that augments prevented further medialization of the joint line and corrected the deficit on average by 10.2 mm (range 6.9-14.3; standard deviation 2.0). The mean bone volume removed during surgery was 1292 mm3 (range 525-2256; standard deviation 527), with this value inclusive of the baseplate post volume (∼800 mm3). Inclination and version were restored to acceptable limits in all cases. ConclusionsReverse shoulder arthroplasty with metallic augments reliably preserves bone and prevents medialization of the joint line in patients with preoperative glenoid bone loss. Further research is required to assess the long-term and functional outcomes of this technique.

Implant Sizing and Positioning in Anatomical Total Shoulder Arthroplasty Using a Rotator Cuff-Sparing Postero-Inferior Approach.

Background: The goal of this study was to compare the effectiveness of a rotator cuff-sparing postero-inferior (PI) approach with subdeltoidal access to the traditional subscapularis-takedown deltopectoral approach, in terms of implant sizing and positioning in anatomical total shoulder arthroplasty (aTSA). Methods: This study involved 18 human cadaveric shoulders with intact rotator cuffs and no evidence of head deforming osteoarthritis. An Eclipse stemless aTSA (Arthrex, Naples, FL, USA) was implanted in nine randomly selected specimens using a standard subscapularis-tenotomy deltopectoral approach, and in the other nine specimens using the cuff-sparing PI approach. Pre- and postoperative antero-posterior (AP) and axillary fluoroscopic radiographs were analyzed by two independent, blinded raters for the following parameters: (1) anatomic and prosthetic neck-shaft angle (NSA); (2) the shift between the anatomic and prosthetic center of rotation (COR); (3) anatomical size matching of the prosthetic humeral head; (4) the calculated Anatomic Reconstruction Score (ARS); (5) glenoid positioning; as well as (6) glenoid inclination and version. Results: While the COR was slightly but significantly positioned (p = 0.031) to be more medial in the PI approach group (3.7 ± 3.4%, range: −2.3% to 8.7%) than in the deltopectoral approach group (−0.2 ± 3.6%, range: −6.9% to 4.1%), on average, none of the remaining measured radiographic parameters significantly differed between both groups (PI approach group vs. deltopectoral group: NSA 130° vs. 127°, p = 0.57; COR supero-inferior, 2.6% vs. 1.0%, p = 0.35; COR antero-posterior, 0.9% vs. 1.7%, p = 0.57; head size supero-inferior, 97.3% vs. 98.5%, p = 0.15; head size antero-posterior, 101.1% vs. 100.6%, p = 0.54; ARS, 8.4 vs. 9.3, p = 0.13; glenoid positioning supero-inferior, 49.1% vs. 51.1%, p = 0.33; glenoid positioning antero-posterior, 49.3% vs. 50.4%, p = 0.23; glenoid inclination, 86° vs. 88°, p = 0.27; and glenoid retroversion, 91° vs. 89°, p = 0.27). Conclusions: A PI approach allows for sufficient exposure and orientation to perform rotator-cuff sparing aTSA with acceptable implant sizing and positioning in cadaveric specimens.

Management of glenoid bone loss with impaction and structural bone grafting in reverse shoulder arthroplasty.

Glenoid bone loss is a commonly encountered problem in complex primary and revision shoulder arthroplasty. Addressing glenoid bone loss is critical to avoid complications like early loosening, impingement, notching and instability. A large number of techniques like bone grafting using autograft or allograft, eccentric reaming, augmented base plates, patient-specific instrumentations and custom-made implants are available to tackle bone loss. We prospectively collected the data of all patients with glenoid defects undergoing primary or revision reverse shoulder replacement between 2004 and 2017. This included demographic data, ranges of motion, Constant-Murley score and Subjective Shoulder Value(SSV). A pre-operative CT scan was done as well to plan the surgery and calculate the glenoid version. At each follow-up, the clinical function and shoulder scores were assessed. Additionally, the radiographs were assessed for graft incorporation, evidence of lysis and calculation of glenoid version. Between 2004 and 2017, 37 patients underwent glenoid bone grafting during reverse shoulder arthroplasty. Average age was 72years (range 46-88). Indications for surgery were cuff tear arthropathy (6 patients); revision of failed other prosthesis (23); primary osteoarthritis (4); rheumatoid arthritis (3); and second-stage revision for infection (1). The glenoid defect was contained in 24 patients, and therefore, impaction graft with a combination of bone graft substitute and/or humeral head autograft was performed. In 13 patients the glenoid defect was severe and uncontainable and therefore a graft-implant composite glenoid was implanted using humeral head autograft or allograft. Average follow-up was 3.6years (range 1-10). Mean Constant score improved from 34 before surgery to 63 after surgery. Mean SSV score improved from 0.9/10 to 8.3/10. Active movements improved significantly with forward elevation increasing from 54° to 123°; abduction from 48° to 123°; external rotation from 24° to 38°; internal rotation from 57° to 70°. Radiographs at final follow-up showed no radiolucencies around the glenoid component and no evidence of loosening of the implant. In 2 cases there was a grade I notching. There was 100% survivorship at the last follow-up. Impaction bone grafting along with structural grafting when required is an effective and reproducible way of managing severe glenoid bone loss. This technique gives consistent and good clinical and radiological results.