Glenoid Shape Research Articles

Magnetic resonance imaging glenohumeral joint analysis before and after muscle transfer in children with obstetric brachial plexus palsy: a cross-sectional study of 10 cases.

This study aims to analyze the impact of muscle transfer on the glenohumeral joint in children with obstetric brachial plexus palsy (OBPP) using MRI by comparing preoperative and 5-year follow-up postoperative imaging findings to determine whether tendon transfers affect the alignment and configuration of the glenohumeral joint. Ten children with obstetric brachial plexus palsy (OBPP) participated in our prospective observational study, and we performed a tendon transfer technique. Every patient had an MRI of both shoulders done at preoperative and at the 5-year mark following the procedure. The glenoid form, glenoid version, humeral head hypoplasia (HHH), and percentage of the humeral head anterior (PHHA) were the parameters that were evaluated. The glenoscapular angle (GSA) was used to evaluate the glenoid version. Following tendon transfer surgery, MRI data show a regression of humeral head hypoplasia, and a statistically significant difference (p=0.0057) was observed between preoperative and postoperative results. Three individuals additionally recovered a normal glenoid shape. None of the remaining patients had a type 3 form; all had a type 2 form. Additionally, compared to the postoperative side, the damaged preoperative side's GSA was much more retroverted (p < 0.05). The mean PHHA for the afflicted shoulder was 25.8%, ranging from 0% to 40%, compared with 40.5% for the postoperative affected shoulder, indicating an improvement in humeral head subluxation (PHHA). As a result, the two results did not differ statistically. While tendon transfers led to only minor improvements in humeral head subluxation, they greatly improved glenoid retroversion and humeral head hypoplasia. It has been established that MRI is a useful diagnostic technique for glenohumeral anomalies due resulting from obstetric brachial plexus palsy.

Effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture

To analyze the effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture. From January 2016 to June 2021, 26 patients with Ideberg typeⅡglenoid fractures were treated with trans-axillary lag screw combined with supporting plate, including 15 males and 11 females. The age ranged from 21 to 75 years, with an average of (43.12±6.56) years old. The Constant-Murley Shoulder joint Scale and University of California at Los Angeles (UCLA) score were used to evaluate the function and clinical efficacy of shoulder joint. All patients were followed up, and the duration ranged from 19 to 42 months, with an average of (30.6±10.5) months. One year after surgery, the Constant-Murley score increased from preoperative 34.9±2.5(ranged, from 28 to 47) to 87.2±6.8(ranged, from 70 to 95). The UCLA score improved from preoperative 17.9±1.7(9 to 25) to 33.1±2.3(29 to 35). Seventeen patients got an excellent result, with 7 good, and 2 fair. None of the patients had infection, screw, and plate loosening, fracture, and other complications after surgery. Two patients had different degrees of Chronic pain in the shoulder during the follow-up period. The treatment of Ideberg typeⅡscapular glenoid fractures through axillary approach with lag screws and supporting steel plates has the advantages of convenient exposure, direct visual restoration of the normal anatomical shape of the scapular glenoid, selection of suitable positions for screw and steel plate placement, achieving better treatment results, and fewer complications. It is an effective and reliable surgical method.

Correlation between glenoid bone structure and recurrent anterior dislocation of the shoulder joint.

The aim of the study was to investigate the anatomical characteristics and symmetry of the bilateral glenoid structures of Chinese people and to explore the relationship between the glenoid bone structure and recurrent anterior dislocation. The control group included 131 individuals with no history of shoulder dislocation. The dislocation group consisted of 131 patients with a history of unilateral shoulder dislocation. All subjects underwent computed tomography scans. Glenoid shape (pear-shaped, inverted comma-shaped, oval-shaped), width, height, depth, version angle, area, maximum fitting circle area and volume were measured. There was no significant difference in normal bilateral glenoid of Chinese people (p > 0.05). There were statistically significant differences in depth, height to width ratio, maximum fitting circle area and shape between the dislocation and control groups (p < 0.05). Regression analyses showed that the glenoid depth (odds ratio [OR] 0.48; p < 0.01), the glenoid height to width ratio (OR 28.61; p < 0.01), the glenoid maximum fitting circle area (OR 1.01; p < 0.01) and the glenoid shape (p <0.05; pear-shaped OR 0.432; inverted comma-shaped OR 0.954) were associated with anterior shoulder instability. Pear-shaped and inverted comma-shaped glenoid had lower risk of recurrent anterior shoulder dislocation compared to oval glenoid. Receiver operating characteristic curve analysis showed that individuals with anterior shoulder instability had smaller glenoid depth and larger height to width ratio and the glenoid maximum fitting circle area compared with the control group. The normal bilateral glenoids of Chinese people are basically symmetrical. The glenoid shape, depth, height to width ratio and maximum fitting circle area are risk factors for recurrent anterior shoulder dislocation. Evaluation of the glenoid bone structure enables more accurate prediction of the risk of recurrent shoulder dislocation.

Glenoid shape is sexually dimorphic

Uniform assessment of the glenoid anatomy is fundamental in establishing uniform standards of care. Subjectivity in classification inherent in the absence of quantification permits deficiency in glenoid assessment methods (e.g., Walch classifications). Therefore, this report aims to objectively quantify the variance of glenoid fossa contours in both sexes via geometric morphometric techniques. A total of 135 glenoid fossae from 135 adult Mexican individuals, who had undergone CT scanning for non-shoulder-related reasons, were randomly selected for this study. Geometric morphometric analysis, including principal component analysis, canonical variate analysis, and two-block partial least squares analysis, was performed on glenoid contours in coronal and axial planes among males and females of varied age groups. The canonical variate analysis of the glenoid revealed sexual dimorphism in both the coronal and axial glenoid contours. Males tend to have a move concave glenoid contour than females, especially in the axial plane. Partial least squares analysis revealed a shape-relationship between coronal and axial contours— when coronal contours are relatively concave, axial contours also exhibit concavity; conversely, when there is minimal concavity in one dimension, there tends to be minimal concavity in the other. This manuscript establishes a novel means of assessing the glenoid cavity through geometric morphometrics; in doing so, the objective and quantifiable methods can be an important supplement to evolving glenoid assessments such as the Walch classification system. The novel approach used in this research revealed sexual dimorphism in the shape of the glenoid cavity as well as a relationship between coronal and axial contours.

Calculating glenoid bone loss based on glenoid height using ipsilateral three-dimensional computed tomography.

To investigate the relationship between glenoid width and other morphologic parameters using three-dimensional (3D) computed tomography (CT) images of native shoulders, and to create a new measurement tool to assess glenoid defects in a Canadian population with established anterior shoulder instability. Forty-three glenoid CT scans were analyzed for patients who underwent contralateral shoulder glenoid reconstruction for anterior shoulder instability between 2012 and 2020. Demographic data were obtained including age, gender and BMI. The subjects were excluded if they had a prior history of ipsilateral shoulder instability, shoulder fractures, or bone tumors. The following glenoid parameters were measured: width (W), height (H), anteroposterior (AP) depth, superior-inferior (SI) depth and version. The shape of the glenoid was also classified into pear, inverted comma or oval. There were 35 male and 8 females with a mean age of 34.5 ± 12.9years. The glenoid width was strongly correlated with the height (R2 = 0.9) and a regression model equation was obtained: W (mm) = 2.5 + 0.7*H (mm). There was also strong correlation with gender (P < 0.001), glenoid shape (P = 0.030), AP and SI depths (P = 0.006 and P < 0.001, respectively). Male gender was associated with higher measurement values for all parameters. The most common glenoid shapes were the pear (46.5%) and oval morphotypes (39.6%) for the whole study group. The native glenoid width can be estimated based on glenoid height using ipsilateral 3D CT. This may help with preoperative planning and surgical decision-making for patients with anterior shoulder instability and glenoid bone loss. III.

Temporomandibular joint shape in anthropoid primates varies widely and is patterned by size and phylogeny.

The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better understanding masticatory function. Here, we present a detailed three-dimensional (3D) geometric morphometric analysis of the cranial component of this joint, the glenoid fossa, across a sample of 17 anthropoid primates, and we evaluate covariation between the glenoid and the cranium and mandible. We find high levels of intraspecific variation in glenoid shape that is likely linked to sexual dimorphism and joint remodeling, and we identify differences in mean glenoid shape across taxonomic groups and in relation to size. Analyses of covariation reveal strong relationships between glenoid shape and a variety of aspects of cranial and mandibular form. Our findings suggest that intraspecific variation in glenoid shape in primates could further be reflective of high levels of functional flexibility in the masticatory apparatus, as has also been suggested for primate jaw kinematics and muscle activation patterns. Conversely, interspecific differences likely reflect larger scale differences between species in body size and/or masticatory function. Results of the covariation analyses dovetail with those examining covariation in the cranium of canids and may be indicative of larger patterns across mammals.

A Three-Dimensional Computed Tomography Radiographic Study -- Can We Predict Glenoid Width Based on Glenoid Height? (216)

Objectives:The purpose of this study was to investigate the relationship between glenoid width and other morphologic parameters using three-dimensional (3D) computed tomography (CT) images of native shoulders in hopes of generating a formula to predict glenoid width which will have utility in planning boney shoulder stabilization surgeries.Methods:102 glenoid images were obtained for patients who underwent contralateral shoulder glenoid reconstruction for anterior shoulder instability between 2012 and 2020. Demographic data was obtained including age, gender and BMI. The subjects were excluded if they had a prior history of ipsilateral shoulder instability, shoulder fractures, or bone tumors. The following glenoid parameters were measured: width (W), height (H), ratio (W/H), anteroposterior (AP) depth, superior-inferior (SI) depth and version. The shape of the glenoid was also classified into pear, inverted comma or oval. Data was analyzed based on gender and age. Simple logistic regression, Kruskal Wallis Rank tests and Fisher Exact tests were performed.Results:There were 71 male and 25 females with a mean age of 39.74 ± 17.88 years. Pear morphotype accounted for most glenoid shapes (46%). The glenoid width was strongly correlated with the height (coefficient = 0.78) and a regression model equation was obtained: W (mm) = 3.4 + 0.68*H (mm). There was also strong correlation with gender (P<0.0001), age (P=0.0384), BMI (P<0.0001), glenoid shape (P=0.0036), height (P=0.0019), AP and SI depths (P<0.0001). Male gender was associated with higher measurement values for all parameters. Older age was significantly correlated with higher glenoid width values in both male and females group. (P=0.0015 and P=0.0104, respectively).Conclusions:The native glenoid width can be easily estimated using solely the glenoid height. This is particularly important for surgical decision making when facing anterior or posterior glenoid defects in patients with shoulder instability.

The Anatomy of Glenoid Concavity-Bony and Osteochondral Assessment of a Stability-Related Parameter.

Glenoid concavity is a crucial factor for glenohumeral stability. However, the distribution of this stability-related parameter has not been focused on in anatomical studies. In this retrospective study, computed tomography (CT) data and tactile measurements of n = 27 human cadaveric glenoids were analyzed with respect to concavity. For this purpose, the bony and osteochondral shoulder stability ratio (BSSR/OSSR) were determined based on the radius and depth of the glenoid shape in eight directions. Various statistical tests were performed for the comparison of directional concavity and analysis of the relationship between superoinferior and anteroposterior concavity. The results proved that glenoid concavity is the least distinctive in anterior, posterior, and anterosuperior direction but increases significantly toward the superior, anteroinferior, and posteroinferior glenoid. The OSSR showed significantly higher concavity than the BSSR for most of the directions considered. Moreover, the anteroposterior concavity is linearly correlated with superoinferior concavity. The nonuniform distribution of concavity indicates directions with higher stability provided by the anatomy. The linear relationship between anteroposterior and superoinferior concavity may motivate future research using magnetic resonance imaging (MRI) data to optimize clinical decision-making toward more personalized treatment of glenoid bone loss.

Radiographic study of effect of lateral placement of bone graft on shoulder joint degeneration after modified arthroscopic Latarjet surgery with elastic fixation

To investigate the mid-term effect of lateral placement of bone graft on shoulder joint degeneration after modified arthroscopic Latarjet surgery with elastic fixation for recurrent anterior shoulder dislocation with an anterior glenoid bone defect. According to the inclusion and exclusion criteria, 18 patients with recurrent anterior shoulder dislocation and anterior glenoid bone defect who received the modified arthroscopic Latarjet surgery with elastic fixation between January 2015 and November 2016 were enrolled in this study. There were 12 males and 6 females with an average age of 26.2 years (range, 19-37 years). The number of shoulder dislocation ranged from 4 to 30 times (mean, 8.8 times). The disease duration was 8-49 months (mean, 23.8 months). The mean anterior glenoid bone defect was 25.2% of the glenoid surface (range, 20%-29%). The mean preoperative Instability Severity Index Score (ISIS) was 7.6 (range, 7-10). According to Samilson-Prieto classification, the shoulder joint degeneration was rated as grade 0 in 13 cases, grade Ⅰ in 3 cases, and grade Ⅱ in 2 cases. Before and after operation, the visual analogue scale (VAS) score, American Society of Shoulder and Elbow Surgery (ASES) score, Walch-Duplay score, Rowe score, and shoulder mobility were used to evaluate the effectiveness. Imaging examination was performed to observe the shoulder joint degeneration, the position of the bone graft, and the postoperative shaping of the scapular glenoid. All patients were followed up 55-62 months, with an average of 59.6 months. There was no neurovascular injuries, infections, fixation-related and bone graft-related complications. No re-dislocation and revision occurred. All patients returned to normal life, 17 of whom returned to sport. The VAS score was significantly decreased and ASES, Walch-Duplay, and Rowe scores were significantly improved at last follow-up ( P<0.05). No significant difference was found in range of motion of forward flexion, abduction, lateral rotation at 90° abduction, internal rotation at 90° abduction, or lateral rotation at 0° between pre- and post-operation ( P>0.05). Three-dimensional CT showed that the centers of all bone grafts were between 3∶30 and 4∶30 (right shoulder) or between 7∶40 and 8∶20 (left shoulder) and no bone grafts were positioned superiorly or inferiorly in the glenoid En-face view. All bone grafts were positioned lateral to the scapular glenoid with an average distance of 3.5 mm (range, 2.3-4.6 mm) in cross-sectional imaging by CT. Compared with the preoperative Samilson-Prieto classification results, all cases showed no progression of shoulder joint degeneration at 36, 48 months and last follow-up. All bone grafts remodeled to a steady state within 24 months after operation. The bone graft and glenoid finally remodeled analogous to the shape of the intact glenoid in the En-face view and became flush with the glenoid rim, remodeling to a curved shape congruent to the humeral head in cross-sectional imaging by CT. The shape of the remodeled glenoid at last follow-up was not significantly different from that at 24 months after operation. The lateral placement of the bone graft during modified arthroscopic Latarjet surgery with elastic fixation do not accelerate the imaging changes of shoulder joint degeneration.

Glenoid Orientation and Profile in Atraumatic or Microtraumatic Posterior Shoulder Instability: Morphological Analysis Using Computed Tomography Arthrogram.

Background:Posterior shoulder instability (PSI) is a relatively uncommon condition that occurs in about 10% of patients with shoulder instability. PSI is usually associated with dislocations due to acute trauma and multidirectional instability, but it can also occur with or without recognizable recurrent microtrauma. The infrequency of atraumatic or microtraumatic PSI and the lack of a full understanding of the pathoanatomy and the knowledge of management can lead to misdiagnosis or delayed diagnosis.Purpose:To evaluate the morphologic factors of the glenoid that are associated with atraumatic or microtraumatic PSI.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Enrolled in this study were patients who underwent arthroscopic posterior labral repair between January 2013 and March 2017 and were diagnosed with posterior glenohumeral instability by means of preoperative computed tomography arthrography (CTA) (n = 39; PSI group). These patients did not have any significant dislocation or subluxation episodes. The morphologic factors of the glenoid as revealed using CTA were compared with the CTA images from a sex-matched control group (n = 117) of patients without PSI who had been diagnosed with adhesive capsulitis in an outpatient clinic. The glenoid version and shape were evaluated between the 2 groups using the CTA findings, and the degree of centricity of the humeral head to the glenoid was assessed in the PSI group. Multivariate logistic regression analysis was performed to identify factors associated with PSI.Results:The results of the multivariate logistic regression analysis indicated no statistically significant difference between the PSI and control groups regarding glenoid version or a flat-shaped glenoid. However, statistically significant between-group differences were found regarding convex glenoid shape, with an odds ratio of 5.39 (95% CI, 1.31-23.35; P = .0207). The proportion of eccentricity was significantly higher in the PSI group (21/39; 54%) versus the control group (47/117; 40%) (P = .031).Conclusion:The presence of convex glenoid shape was significantly associated with atraumatic or microtraumatic PSI. Humeral head eccentricity accounted for a high percentage of convex glenoid shape. However, there was no significant correlation between PSI and glenoid retroversion.

State-of-the art treatment of bony defects in anterior shoulder instability—the European perspective

AbstractDepending on their size, all glenoid defects lead to a certain amount of loss of glenohumeral stability and therefore may represent a risk factor for the recurrence of instability after soft tissue stabilization procedures. The degree of loss of stability depends not only on the extent of the defect but also on differences in individual constitutional shape, which need to be analyzed in a three-dimensional context. Additionally, patient-specific factors such as age and activity level have a significant influence on the clinical effect of glenoid bone loss. Therefore, when treating a patient with glenoid bone loss, a bony glenoid reconstruction surgery in the form of a free bone graft transfer or Latarjet should be considered based on the extent of the defect, native glenoid shape, age, and activity level. Furthermore, in the presence of a relevant Hill–Sachs defect, the addition of a remplissage to a Bankart procedure should be considered or the use of a bony glenoid augmentation procedure instead.

Shoulder-Pacemaker Treatment Concept for Posterior Positional Functional Shoulder Instability: A Prospective Clinical Trial

Background: Pathological muscle activation patterns of the external rotators and periscapular muscles can result in posterior positional functional shoulder instability (PP-FSI). In several patients, physical therapy and surgical treatment are not successful. Purpose: The shoulder-pacemaker treatment concept was evaluated prospectively in patients with PP-FSI and previously failed conventional therapy attempt. Study Design: Case series; Level of evidence, 4. Methods: A negative selection of 24 consecutive cases of noncontrollable PP-FSI in 16 patients with previously failed conventional therapy were included in this prospective study. The shoulder-pacemaker treatment consisted of an electrical muscle stimulation–based therapy protocol with 9 to 18 one-hour treatment sessions. Two patients were excluded because of nonadherence to the training schedule, leaving a final study cohort of 21 cases in 14 patients. Follow-up included assessment of clinical function, impairment during daily activities and sports, satisfaction, Western Ontario Shoulder Instability Index (WOSI), Rowe score, and Subjective Shoulder Value at 0 weeks, 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months after intervention. Results: WOSI, Subjective Shoulder Value, and Rowe score showed a highly significant improvement at all time points of follow-up (P < .001). Young age (P = .005), low weight (P = .019), shoulder activity level (P = .003), unilateral affliction (P = .046), and higher baseline WOSI score (P = .04) were associated with a better treatment effect. Cases with increased glenoid retroversion, posterior scapulohumeral decentering, and dysplastic bony glenoid shape showed a trend toward shorter treatment effect duration. No complications during the intervention or follow-up period were observed. Conclusion: The shoulder-pacemaker therapy concept is an effective treatment with rapid improvement and sustained outcome over the course of 2 years in patients with noncontrollable PP-FSI with previously failed conventional treatment. Young and more athletic patients with lower weight and unilateral pathology respond best to the treatment.

The Biomechanical Effect of Bone Grafting and Bone Graft Remodeling in Patients With Anterior Shoulder Instability

Background: Individual constitutional differences in glenoid shape and bone remodeling require a patient-specific and longitudinal approach to evaluate the biomechanical effects of glenoid bone grafting in patients with anterior shoulder instability. Purpose: To quantify the longitudinal, in vivo, biomechanical effects of bone grafting, bone graft remodeling, and glenoid shape in patients with anterior shoulder instability by means of patient-specific finite element models. Study Design: Descriptive laboratory study. Methods: In total, 25 shoulders of 24 patients with anterior shoulder instability and anterior glenoid bone loss underwent an arthroscopic iliac crest bone graft transfer (ICBGT) procedure with either autologous or allogenic bone. Patient-specific finite element simulations based on preoperative, postoperative, and follow-up computed tomography scans were used to quantify the bone-mediated stability ratio (SR) and the distance to dislocation. Additionally, the relationship between glenoid morphological parameters and the SR was assessed. Results: The ICBGT procedure significantly increased the SR and distance to dislocation in the 2-, 3-, and 4-o’clock directions immediately after the surgical intervention (P < .01) in both the autograft and the allograft groups. Although the SR and distance to dislocation decreased subsequently, autografts showed long-term effects on SR and dislocation distance in the 3-o’clock direction (P < .01) and on SR in the 4-o’clock direction (P < .01). Allografts showed no significant effect on SR and dislocation distance in long-term follow-up (P > .05). Overall, glenoid retroversion as well as cavity depth predicted stability in all 4 dislocation directions, with glenoid cavity depth showing the highest correlation coefficients (R = 0.71, 0.8, 0.73, and 0.7 for 2-, 3-, 4-, and 5-o’clock, respectively). Conclusion: The autologous ICBGT procedure biomechanically improved anterior shoulder stability in long-term follow-up, whereas the use of allografts did not show any bone-mediated biomechanical effect at follow-up due to resorption. Furthermore, in addition to measurements of defect extent, the glenoid depth and version seem to be useful parameters to determine the biomechanical effect and need for glenoid bone grafting in patients with shoulder instability. Clinical Relevance: This study proposes the use of autologous bone grafts for a successful long-term stabilization effect. Additionally, this study proposes additional glenoid morphological measures to predict shoulder stability.

The Shape Solidity of the Glenoid Fossa of the Scapula is Sexually Dimorphic: A New Approach to Understanding the Glenoid Fossa

Sexual dimorphism in the size of the glenoid fossa of the scapula is well‐established; however, there remains little information with regard to differences in glenoid shape between sexes. Therefore, this study assessed 71 glenoid fossae from dry scapula. Three differential equations were utilized to ensure that scapulae were appropriately sexed and, accordingly, included in the study. When all three equations were in agreement with regard to sex, the scapula was included for study. A total of 64 scapulae (45 females and 19 males) met inclusion criteria. Shape parameters that were assessed included circularity (4π*area/perimeter2), roundness (4*area/π*major axis2), aspect ratio of a bet‐fit ellipse (major axis/minor axis), and solidity (area/area of a convex hull). Shape parameters such as circularity, aspect ratio, and roundness were not significantly different between sexes; however, solidity was significantly different between females and males (p=0.0475). The results demonstrate a difference in the concavity of the boundary of the glenoid fossa between sexes. Further study should elucidate the functional differences in glenohumeral joint biomechanics with regard to the solidity of the glenoid fossa while taking sex into consideration.Support or Funding InformationWV Research Challenge Fund [HEPC.dsr.17.06]

Characteristics of functional shoulder instability

Pathologicactivation pattern of muscles can cause shoulder instability. We propose to call this pathology functional shoulder instability (FSI). The purpose of this prospective study was to provide an in-detail description of the characteristics of FSI. In the year 2017, a total of 36 consecutive cases of FSI presenting to our outpatient clinic were prospectively collected. Diagnostic investigation included a pathology-specific questionnaire, standardized clinical scores, clinical examination, psychological evaluation, video and dynamic fluoroscopy documentation of the instability mechanism, as well as magnetic resonance imaging (MRI). In a final reviewing process, the material from all collected cases was evaluated and, according to the observed pattern, different subtypes of FSI were determined and compared. Based on the pathomechanism, positional FSI (78%) was distinguished from nonpositional FSI (22%). Controllable positional FSI was observed in 6% of all cases and noncontrollable positional FSI in 72%, whereas controllable and noncontrollable nonpositional FSI were each detected in 11% of the cases. The different subtypes of FSI showed significant differences in all clinical scores (Western Ontario Shoulder Instability Index: P = .002, Rowe Score: P = .001, Subjective Shoulder Value: P = .001) and regarding functional impairment (shoulder stability: P < .001, daily activities: P = .001, sports activities: P < .001). Seventy-eight percent had posterior, 17% anterior, and 6% multidirectional instability. Although several patients showed constitutional glenoid shape alterations or soft tissue hyperlaxity, only few patients with acquired minor structural defects were observed. FSI can be classified into 4 subtypes based on pathomechanism and volitional control. Depending on the subtype, patients show different degrees of functional impairment. The majority of patients suffer from unidirectional posterior FSI.

Clinical significance of cervical MRI in brachial plexus birth injury

Background and purpose — Patient selection for nerve surgery in brachial plexus birth injury (BPBI) is difficult. Decision to operate is mostly based on clinical findings. We assessed whether MRI improves patient selection.Patients and methods — 157 BPBI patients were enrolled for a prospective study during 2007–2015. BPBI was classified at birth as global plexus injury (GP) or upper plexus injury (UP). The global plexus injury was subdivided into flail upper extremity (FUE) and complete plexus involvement (CP). Patients were seen at set intervals. MRI was scheduled for patients that had either GP at 1 month of age or UP with no antigravity biceps function by 3 months of age. Type (total or partial avulsion, thinned root), number and location of root injuries and pseudomeningoceles (PMC) were registered. Position of humeral head (normal, subluxated, dislocated) and glenoid shape (normal, posteriorly rounded, pseudoglenoid) were recorded. Outcome was assessed at median 4.5 years (1.6–8.6) of age.Results — Cervical MRI was performed on 34/157 patients at median 3.9 months (0.3–14). Total root avulsions (n = 1–3) were detected on MRI in 12 patients (8 FUE, 4 CP). Reconstructive surgery was performed on 10/12 with total avulsions on MRI, and on all 10 with FUE at birth. Sensitivity and specificity of MRI in detecting total root avulsions was 0.88 and 1 respectively. Posterior shoulder subluxation/dislocation was seen in 15/34 patients (3.2–7.7 months of age).Interpretation — Root avulsion(s) on MRI and flail upper extremity at birth are both good indicators for nerve surgery in brachial plexus birth injury. Shoulder pathology develops very early in permanent BPBI.

Glenoid morphology is associated with the development of instability arthropathy

Instability arthropathy (IA) is a major long-term concern in patients with anterior shoulder instability. This study investigated the association of glenoid morphology with the development of IA. The study included 118 patients with unilateral anterior shoulder instability and available bilateral computed tomography scans. Instability-specific information was obtained from all patients. The glenoid morphology of the affected shoulder was compared with the nonaffected contralateral side resembling the constitutional preinjury glenoid shape. Both shoulders were evaluated independently by 3 observers to assess the grade of IA according to a Comprehensive Arthropathy Rating (CAR) system. Associations between IA and the glenoid morphology parameters were investigated. The average glenoid retroversion (P < .001), glenoid depth (P < .001), glenoid diameter (P < .001), and the bony shoulder stability ratio (P < .001) of the affected shoulder were significantly reduced compared with the contralateral side due to bony defects in 79.6% of the patients. The CAR of the affected side was significantly higher (P < .001), with more osteophytes (P = .001) and more sclerosis and cysts (P < .001). Differences in CAR (Δ-CAR) correlated positively with the age at the time of the computed tomography scan (P < .001), age at the initial dislocation (P = .001), size of the glenoid defect (P = .005), and the contralateral glenoid depth (P = .011), glenoid diameter (P = .016), and bony shoulder stability (P = .029), and negatively with glenoid retroversion of the affected side (P = .027). Development of IA arthropathy is associated not only with the age of the patients but also with morphologic parameters of the glenoid, including glenoid defect size and the constitutional glenoid concavity shape.

Small anteroposterior inclination of the acromion is a predictor for posterior glenohumeral erosion (B2 or C)

Anatomic factors associated with static posterior translation of the humeral head with or without glenohumeral osteoarthritis are unknown. We tested the hypothesis that there is an association between glenoid wear, glenoid version, and/or anteroposterior acromial tilt. Ninety-nine patients with glenohumeral joint degeneration involving advanced glenoid cartilage wear and/or rotator cuff disease scheduled for anatomic or reverse total shoulder replacement underwent standardized conventional radiographic and computed tomographic shoulder imaging. Measurements included glenoid version, humeral torsion, posterior acromial slope, and critical shoulder angle. The glenoid shape was classified according to Walch et al, and the integrity of the rotator cuff was assessed. Patients with glenoid type B2 or C had a median of 4° more glenoid retroversion (P = .022), a 5° less steep acromion (posterior acromial slope, 61° vs 56°; P = .004), and a higher combined score (glenoid version minus slope; odds ratio, 0.93 [95% confidence interval, 0.89-0.97]; P < .001; cutoff, -27°) than those with type A or B1. When the rotator cuff was torn, osteoarthritic changes were milder than when the cuff was intact (eg, P < .001 for supraspinatus). The study's hypothesis that the bony anatomy of the scapula and in particular the acromion is correlated with the type of glenoid wear was confirmed. Both a more horizontal acromial orientation in the sagittal plane and increased posterior glenoid version are found in osteoarthritis of the shoulder associated with eccentric, posterior glenoid wear. Tears of the rotator cuff are significantly associated with concentric osteoarthritis of the glenoid.

A statistical shape model to predict the premorbid glenoid cavity

This study proposes a method for inferring the premorbid glenoid shape and orientation of scapulae affected by glenohumeral osteoarthritis (OA) to inform restorative surgery. A statistical shape model (SSM) built from 64 healthy scapulae was used to reconstruct the premorbid glenoid shape based on anatomic features that are considered unaffected by OA. First, the method was validated on healthy scapulae by quantifying the accuracy of the predicted shape in terms of surface distance, glenoid version, and inclination. The SSM-based reconstruction was then applied to 30 OA scapulae. Glenoid version and inclination were measured fully automatically and compared between the original OA glenoids, SSM-based glenoid reconstructions, and healthy scapulae. Validation on healthy scapulae showed a root-mean-square surface distance between original and predicted glenoids of 1.0 ± 0.2 mm. The prediction error was 2.3° ± 1.8° for glenoid version and 2.1° ± 2.0° for inclination. When applied to an OA dataset, SSM-based reconstruction restored average glenoid version and inclination to values similar to the healthy situation. No differences were observed between average orientation values measured on SSM-based reconstructed and healthy scapulae (P ≥ .10). However, the average orientation of the reconstructed premorbid glenoid differed from the average orientation of OA glenoids for Walch classes A1 (version) and B2 (version, inclination, and medialization). The proposed SSM can predict the premorbid glenoid cavity of healthy scapulae with millimeter accuracy. This technique has the potential to reconstruct the premorbid glenoid cavity shape, as it was prior to OA, and thus to guide the positioning of glenoid implants in total shoulder arthroplasty.

Modeling the Variability of Glenoid Geometry in Intact and Osteoarthritic Shoulders

The objective of this research is to model the geometric variability of the glenoid of the scapula. The glenoid is the “socket” component of the “ball and socket” connection of the shoulder joint. The model must capture the observed variability with sufficient resolution such that it informs both operative and design decisions. Creating the model required the application of existing mathematical and statistical modeling approaches, including geometric fitting, radial basis functions (RBFs), and principal component analysis (PCA). The landmark identification process represented the glenoid in a new manner. This work was validated against existing approaches and computed tomography (CT) scans from 42 patients. Information on the range of shoulder geometries can assist with preoperative planning as well as implant design for total shoulder arthroplasty (TSA). PCA was used to quantify the variability of shape across landmarks used to represent the glenoid shape. These landmark locations could be used to generate full surface meshes of existing glenoids or new glenoid models synthesized by changing principal components (PC). The process of creation of these shoulder geometries may be useful for the study of other joints. The models created will help surgeons and engineers to understand the effects of osteoarthritis on bone geometry, as well as the range of variability present in healthy shoulders.