Guidelines for humeral subluxation cutoff values: a comparative study between conventional, reoriented, and three-dimensional computed tomography scans of healthy shoulders

The arthroscopic double-button Latarjet does not modify the static posterior translation of the humeral head

INTRODUCTION

The Latarjet procedure treats anterior instability of the shoulder and is based on a triple anterior lock, where the conjoint tendon straps the lower third of the subscapularis muscle. Excessive posterior translation of the humeral head is a known risk factor for shoulder osteoarthritis. No in vivo study has investigated the effect of the bone block on the posterior static translation of the humeral epiphysis. The purpose of this study was to evaluate the effect of the bone block on the static posterior translation of the humeral head. The hypothesis was that this procedure increased this translation.

MATERIALS AND METHODS

This retrospective study included patients treated arthroscopically for anterior shoulder instability by a double-button Latarjet. An independent examiner analyzed the CT scans preoperatively, at 15 days, and at least 6 months postoperatively according to a standardized protocol. The analysis focused on the position of the bone block in the axial and coronal planes relative to the glenoid. The posterior translation was automatically calculated using the Blueprint© planning software.

RESULTS

Thirty-five patients were included with a mean age of 25 years (16-43), according to a 4M/1F sex ratio. The graft was perfectly flush to the subchondral bone in 63% (n=22) of cases and subequatorial in 91% (n=32). Preoperative posterior humeral translation was 52%. The mean immediate postoperative posterior humeral translation was 56%, and 57% at more than 6 months. The change in mean posterior humeral translation between preoperative/6 months was +0.94% [-20%; +12%] (p=0.29) and immediate postoperative/6 months +0.34% [-18%; +15%] (p=0.84). Gender, hypermobility and the axial position of the bone block did not influence the change in posterior humeral translation. The equatorial position of the bone block appeared to increase posterior humeral translation by +10%±5.2% [-0.427; 20.823] (p=0.07).

CONCLUSION

This work refutes our initial hypothesis. The change in static posterior humeral translation after arthroscopic Latarjet bone block remains stable at more than 6 months of follow-up. This procedure does not alter the anatomical position of the humeral head in relation to the glenoid. On the other hand, a more cranial positioning of the bone block could have an influence.

LEVEL OF EVIDENCE

IV.

Reference values and influencing factors of the glenohumeral subluxation index: a study on 3004 participants

BACKGROUND

The primary objective of this study was to examine the glenohumeral subluxation index (GHSI) in a large general population cohort and to define reference values. Glenohumeral subluxation is important in the development and prediction of pathological states of the shoulder joint and in total shoulder arthroplasty. Therefore, another objective was to examine the influence of age, sex, body mass index, and body height and weight on GHSI.

METHODS

GHSI according to Walch was measured on bilateral magnetic resonance imaging of 3004 participants of the Study of Health in Pomerania (SHIP, aged 21-90 years). SHIP drew a sample of the adult general population of Pomerania (Northeastern Germany). Reference values for GHSI were assessed by quantile regression models. Associations of sex, age, and anthropometric markers with the GHSI were calculated by linear regression models.

RESULTS

A reference range between 42% and 55% for men with a mean of 49% ± 4% was defined, while the upper reference limit for women was 1% higher (mean, 50% ± 4%). Age was inversely associated with the GHSI in males (P < 0.001), while no significant association in females was observed (P = .625). Body weight and body mass index were positively associated (P < .001) without effect modification by sex. Heavy mechanical oscillations on the upper extremity showed no significant association with GHSI (P = .268).

CONCLUSION

The reference values for GHSI were expanded to a range of 42%-57% on magnetic resonance imaging. Several associations between GHSI and anthropometric properties are present. According to these associations, adjusted formulas are provided to enable individual, patient-specific diagnostics and therapy. Nevertheless, the clinical picture cannot be neglected.

Posterior stability of the shoulder depends on acromial anatomy: a biomechanical study of 3D surface models

PURPOSE

Primary glenohumeral osteoarthritis is commonly associated with static posterior subluxation of the humeral head. Scapulae with static/dynamic posterior instability feature a superiorly and horizontally oriented acromion. We investigated whether the acromion acts as a restraint to posterior humeral translation.

METHODS

Five three-dimensional (3D) printed scapula models were biomechanically tested. A statistical shape mean model (SSMM) of the normal scapula of 40 asymptomatic shoulders was fabricated. Next, a SSMM of scapular anatomy associated with posterior subluxation was generated using data of 20 scapulae ("B1"). This model was then used to generate three models of surgical correction: glenoid version, acromial orientation, and acromial and glenoid orientation. With the joint axially loaded (100N) and the humerus stabilized, an anterior translation force was applied to the scapula in 35°, 60° and 75° of glenohumeral flexion. Translation (mm) was measured.

RESULTS

In the normal scapula, the humerus translates significantly less to contact with the acromion compared to all other configurations (p < .000 for all comparisons; i.e. 35°: "normal" 8,1 mm (± 0,0) versus "B1" 11,9 mm (± 0,0) versus "B1 Acromion Correction" 12,2 mm (± 0,2) versus "B1 Glenoid Correction" 13,3 mm (± 0,1)). Restoration of normal translation was only achieved with correction of glenoid and acromial anatomy (i.e. 75°: "normal" 11 mm (± 0,8) versus "B1 Acromion Correction" 17,5 mm (± 0,1) versus "B1 Glenoid Correction" 19,7 mm (± 1,3) versus "B1 Glenoid + Acromion Correction" 11,5 mm (± 1,1)).

CONCLUSIONS

Persistence or recurrence of static/dynamic posterior instability after correction of glenoid version alone may be related to incomplete restoration of the intrinsic stability that is conferred by a normal acromial anatomy.

LEVEL OF EVIDENCE V

biomechanical study.

Correction of Static Posterior Shoulder Subluxation by Restoring Normal Scapular Anatomy Using Acromion and Glenoid Osteotomies: A Case Report

CASE

A 40-year-old man presented with progressive shoulder pain, associated with static posterior subluxation and mild eccentric glenohumeral osteoarthritis. Compared with a mean statistical shape model of a normal shoulder, the patient's acromion was abnormally high and horizontal, and the glenoid abnormally inclined inferiorly and minimally retroverted. Restoration of normal scapular anatomy using 3-dimensional planned acromial and glenoid osteotomies led to recentering of the joint and full shoulder function up to 24 months postoperatively.

CONCLUSION

The correction of associated acromial and glenoid malformation can revert early static posterior subluxation of the shoulder. Whether successful recentering prevents progression of osteoarthritis remains to be established.

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 (r_s  = 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.

Walch B2 glenoids. 2D vs 3D comparison of humeral head subluxation and glenoid retroversion

Background

The posterior subluxation and glenoid version in Walch B2 glenoids are routinely assessed by 2-dimensional (2D) computed tomography (CT). Different methods of calculation are used to analyze these parameters. Alternatively, the rising use of 3-dimensional (3D) planification tools in arthroplasty requires the clarification if the 3D measurements are equivalent to 2D. The aim of this study was to compare B2 glenoids characteristics between 2D CT assessment method and 3D automated software method.

Methods

CT scans from patients who underwent a shoulder arthroplasty were identified. In the 2D method, measurement of glenoid version was determined. Measurement of the humeral head subluxation (HHS) (scapula axis method) was determined by the percentage of the humeral head posterior to the Friedman line (scapula axis). Three-dimensional analysis allowed an automated segmentation of the humerus and scapula, definition of scapular planes, and determination of glenoid version and HHS.

Results

Fifty-one CT scans met inclusion criteria. The intraobserver and interobserver reliability of the 2D retroversion (RV) and 2D HHS intraclass correlation coefficient was excellent (intraclass correlation coefficient>0.9).The median RV was 16° [12-20] in 2D and 19° [16-23] in 3D (P < .0001). The median subluxation was 71% [66-75] in 2D and 81% [78-86] in 3D (P < .0001). Linear regression analysis demonstrated low positive correlation between RV and subluxation in 2D and 3D (R² = 0.31 and R² = 0.23, respectively).

Discussion/Conclusion

The assessment of version and HHS in Walch B2 glenoids between 2D CT and a 3D planification were significantly different. Low correlation between RV and HHS was observed (2D and 3D assessment).

Determination of predisposing scapular anatomy with a statistical shape model-Part II: shoulder osteoarthritis

HYPOTHESIS AND BACKGROUND

Shoulder osteoarthritis can be divided into different glenoid types (A, B, C, and D) and subtypes. The aim of this study was to investigate if there is an association between the prearthropathy scapular anatomy, shoulder osteoarthritis, and different glenoid types and subtypes.

METHODS

Using principal components analysis, a statistical shape model (SSM) of the scapula was constructed from a data set of 110 computed tomographic (CT) scans. These subjects formed the control group. Next, CT scan images of 117 patients with osteoarthritis were classified according to the modified Walch classification. A complete 3-dimensional (3D) scapular bone model was created for every patient, and using the SSM, a reconstruction of their prearthropathy scapular anatomy was performed. Automated 3D measurements were performed in both the patient and control group to obtain glenoid version and inclination, critical shoulder angle (CSA), posterior acromial slope (PAS), lateral acromion angle, scapular offset, and the rotational alignment of the coracoacromial complex. These parameters were compared between controls, patients with osteoarthritis, and glenoid types and subtypes.

RESULTS

Mean version and inclination for the control group was 6° retroversion and 8° superior inclination (both SD 4°). The mean CSA, PAS, coracoid-posterior acromion angle, posterior acromion-scapular plane angle, and fulcrum axis ratio were 30° (SD 4°), 64° (SD 8°), 116° (SD 9°), 55° (SD 7°), and 46% (SD 4%), respectively. Patients with osteoarthritis had a significant lower CSA, posterior acromion-scapular plane angle, coracoid-posterior acromion angle, and fulcrum axis ratio (27°, 50°, 111°, and 44%, all P < .001). We found a significant difference between the control group and the respective glenoid types for the following parameters: mean CSA and coracoid-posterior acromion angle for A glenoids (27°, P = .001, and 111°, P = .007); mean version, CSA, PAS, coracoid-posterior acromion angle, posterior acromion-scapular plane angle, and fulcrum axis ratio for B glenoids (11°, 27°, 71°, 111°, 49°, and 43%, all P < .001); and mean version, CSA, and posterior acromion-scapular plane angle for D glenoids (2°, P = .002, 26°, P = .003, and 48°, P = .007).

DISCUSSION

There seems to be an association between prearthropathy scapular anatomy and shoulder osteoarthritis. A small lateral extension and less posterior rotation of the acromion is associated with shoulder osteoarthritis and is present in almost all types and subtypes of glenoid morphology. Furthermore, B and D glenoids are associated with, respectively, a more and less pronounced prearthropathy glenoid retroversion.

The Evolution of the Walch Classification for Primary Glenohumeral Arthritis

Our understanding of the pathology of and treatment for glenohumeral arthritis (GHA) has grown dramatically in the past few decades. Original observations regarding patterns of glenoid erosion, glenoid retroversion, and posterior humeral head subluxation in patients with primary GHA were documented in the 1980s and early 1990s. In the late 1990s, Walch et al proposed what is now the most widely used classification system to describe the characteristic pathology of GHA. Improved understanding of both premorbid and pathologic anatomies, along with advancements in imaging, have steered modifications in this classification system. These changes have improved its reliability and helped to further guide management decisions. The purpose of this article is to review the evolution of the Walch classification, understand the rationale behind the modifications, and discuss potential future developments.

Does commercially available shoulder arthroplasty preoperative planning software agree with surgeon measurements of version, inclination, and subluxation?

BACKGROUND

Preoperative planning with commercially available imaging software in shoulder arthroplasty may allow for improved decision-making and more accurate placement of the glenoid component.

METHODS

A total of 81 consecutive shoulder computed tomography scans obtained for preoperative planning purposes for shoulder arthroplasty were analyzed by commercially available software from 4 companies (Blueprint: Wright Medical, Memphis, TN, USA; GPS: Exactech, Gainesville, FL, USA; Materialise: DJO, Vista, CA, USA; and VIP: Arthrex, Naples, FL, USA) and by 5 fellowship-trained sports medicine/shoulder surgeons. Inclination, version, and subluxation of the humerus were measured in a blinded fashion on axial and coronal sequences at the mid-glenoid. Surgeon measurements were analyzed for agreement and were compared with the 4 commercial programs.

RESULTS

Surgeon reliability was acceptable for version (intraclass correlation coefficient [ICC]: 0.876), inclination (ICC: 0.84), and subluxation (ICC: 0.523). Significant differences were found between surgeon and commercial software measurements in version (P = .03), inclination (P = .023), and subluxation (P < .001). Software measurements tended to be more superiorly inclined (average -2° to 2° greater), more retroverted (average 2°-5° greater), and more posteriorly subluxed (average 7°-10° greater) than surgeon measurements. In comparing imaging software measurements, only Blueprint was found to produce significantly different version measurements than surgeon measurements (P = .02).

CONCLUSION

Preoperative planning software for shoulder arthroplasty has limited agreement in measures of version, inclination, and subluxation measurements, whereas surgeons have high inter-reliability. Surgeons should be cautious when using commercial software planning systems and when comparing publications that use different planning systems to determine preoperative glenoid deformity measurements.

Restoration of the Posterior Glenoid in Recurrent Posterior Shoulder Instability Using an Arthroscopically Placed Iliac Crest Bone Graft: A Computed Tomography-Based Analysis

Background

Posterior shoulder instability is uncommon, and its treatment is a challenging problem. An arthroscopically assisted technique for posterior iliac crest bone grafting (ICBG) has shown promising short- and long-term clinical results. Changes as shown on imaging scans after posterior ICBG for posterior shoulder instability have not been investigated in the recent literature.

Purpose

To evaluate changes on computed tomography (CT) after arthroscopically assisted posterior ICBG and to assess clinical outcomes.

Study Design

Case series; Level of evidence, 4.

Methods

Patients with preoperative CT scans and at least 2 postoperative CT scans with a minimum follow-up of 2 years were included in the evaluation. Of 49 initial patients, 17 (follow-up rate, 35%) met the inclusion criteria and were available for follow-up. We measured the glenoid version angle and the glenohumeral and scapulohumeral indices on the preoperative CT scans and compared them with measurements on the postoperative CT scans. Postoperatively, graft surface, resorption, and defect coverage were measured and compared with those at early follow-up (within 16 months) and final follow-up (mean ± SD, 6.6 ± 2.8 years).

Results

The mean preoperative glenoid version was -17° ± 13.5°, which was corrected to -9.9° ± 11.9° at final follow-up (P < .001). The humeral head was able to be recentered and reached normal values as indicated by the glenohumeral index (51.8% ± 6%; P = .042) and scapulohumeral index (59.6% ± 10.2%; P < .001) at final follow-up. Graft surface area decreased over the follow-up period, from 24% ± 9% of the glenoid surface at early follow-up to 17% ± 10% at final follow-up (P < .001). All clinical outcome scores had improved significantly. Progression of osteoarthritis was observed in 47% of the shoulders.

Conclusion

Arthroscopically assisted posterior ICBG restored reliable parameters as shown on CT scans, especially glenoid version and the posterior subluxation indices. Graft resorption was common and could be observed in all shoulders. Patient-reported clinical outcome scores were improved. Osteoarthritis progression in almost 50% of patients is concerning for the long-term success of this procedure.

Three-dimensional geometry of the normal shoulder: a software analysis

BACKGROUND

Three-dimensional (3D) geometry of the normal glenohumeral bone anatomy and relations is poorly documented. Our aims were (1) to determine the 3D geometry of the normal glenohumeral joint (GHJ) with reference to the scapular body plane and (2) to identify spatial correlations between the orientation and direction of the humeral head and the glenoid.

METHODS

Computed tomographies (CTs) of the normal, noninjured GHJ were collected from patients who had undergone CTs in the setting of (1) polytrauma, (2) traumatic head injury, (3) chronic acromioclavicular joint dislocations, and (4) unilateral trauma with a contralateral normal shoulder. We performed 3D segmentation and measurements with a fully automatic software (Glenosys; Imascap). Measurements were made in reference to the scapular body plane and its transverse axis. Geometric measurements included version, inclination, direction, orientation, best-fit sphere radius (BFSR), humeral subluxation, critical shoulder angle, reverse shoulder angle, glenoid area, and glenohumeral distance. Statistical correlations were sought between glenoid and humeral 3D measurements (Pearson correlation).

RESULTS

A total of 122 normal GHJs (64 men, 58 women, age: 52 ± 17 years) were studied. The glenoid BFSR was always larger than the humerus BFSR (constant factor of 1.5, standard deviation = 0.2). The mean glenoid version and inclination were -6° ± 4° and 7° ± 5°, respectively. Men and women were found to have significantly different values for inclination (6° vs. 9°, P = .02), but not for version. Humeral subluxation was 59% ± 7%, with a linear correlation with glenoid retroversion (r = -0.70, P < .001) regardless of age. There was a significant and linear correlation between glenoid and humeral orientation and direction (r = 0.72 and r = 0.70, P < .001).

CONCLUSION

The 3D geometry of the glenoid and humeral head present distinct limits in normal shoulders that can be set as references in daily practice: version and inclination are -6° and 7°, respectively, and humeral posterior subluxation is 59%; interindividual variations, regardless of the size, are relative to the scapular plane. There exists a strong correlation between the position of the humeral head and the glenoid orientation and direction.

The Characteristics of the Favard E4 Glenoid Morphology in Cuff Tear Arthropathy: A CT Study

Background: Cuff tear arthropathy (CTA) is characterized by superior migration of the humeral head with superior erosion of the glenoid. Rarely, humeral head migration can be anteroinferior with associated anterior erosion of the glenoid, a pattern described by Favard as the type E4 glenoid. The purpose of this retrospective imaging study was to analyze the 2D and 3D characteristics of the E4 glenoid. Methods: A shoulder arthroplasty database of 258 cuff tear arthropathies was examined to identify patients with an E4 type deformity. This resulted in a study cohort of 15 females and 2 males with an average age of 75 years. All patients had radiographs and CT scans available for analysis. CT-scan DICOM (Digital Imaging and Communications in Medicine) data were uploaded to a validated three-dimensional (3D) imaging software. Muscle fatty infiltration, glenoid measurements (anteversion, inclination), and humeral head subluxation according to the scapular plane were determined. Results: The mean anteversion and inclination of the E4 cohort were 32° ± 14° and −5° ± 2, respectively. The mean anterior subluxation was 19% ± 16%. All cases had severe grade 3 or 4 fatty infiltration of the infraspinatus, whereas only 65% had grade 3 or 4 subscapularis fatty infiltration. A significant correlation existed between glenoid anteversion and humeral head subluxation (p < 0.001), but no correlation was found with muscle fatty infiltration. The CT analysis demonstrated an acquired erosive biconcave morphology in 11 patients (65%) and monoconcavity in 6 patients (35%). Conclusion: The E4 type glenoid deformity in cuff tear arthropathy is characterized by an anterior erosion and anteversion associated with anterior subluxation of the humeral head.

Clinical and radiographic outcomes of an all-polyethylene fluted central peg glenoid component, implanted utilizing an off-label, uncemented technique, at a minimum 5-year follow-up

BACKGROUND

Glenoid component loosening remains an important concern in anatomic total shoulder arthroplasty. The aim of this study was to evaluate the clinical and radiographic results of a fully uncemented all-polyethylene fluted central peg bone-ingrowth glenoid component at a minimum 5-year follow-up.

METHODS

Thirty-five shoulders in 31 patients (mean age, 73 years) with a mean follow-up of 100 months were retrospectively evaluated at an early and mid-term time point for Constant score (CS). Computed tomography visualized glenoid component fixation at both time points.

RESULTS

Mean CS improved from 40 preoperatively to 66 postoperatively at latest follow-up (P < .001). A mean CS of 74 at early follow-up remained consistent with a mean CS of 66 at latest follow-up (P = .158), with only strength demonstrating a decrease over time (P < .001). An initial osseointegration rate of 81% at early follow-up decreased to 71% at latest follow-up with 74% of the shoulders demonstrating progressive radiolucent lines, resulting in a radiographic loosening rate of 31%. Of the 35 shoulders, 4 were revised (survival rate of 88%), of which 2 due to symptomatic aseptic loosening.

CONCLUSIONS

Uncemented fixation of an all-polyethylene central peg bone-ingrowth glenoid was associated with satisfactory clinical and radiographic scores, and an acceptable revision rate at mid- to long-term follow-up. Despite initial bony osseointegration in the majority of cases, radiographic loosening over time remains a concern, potentially jeopardizing long-lasting fixation of this type of glenoid component when implanted in an off-label uncemented fashion.

Reduction of scapulohumeral subluxation with posterior augmented glenoid implants in anatomic total shoulder arthroplasty: Short-term 3D comparison between pre- and post-operative CT

BACKGROUND

Failure rates in anatomic total shoulder arthroplasty (aTSA) are higher in case of asymmetric glenoid bone loss secondary to posterior wear, and in persistent static posterior subluxation of the humeral head (PSH).

HYPOTHESIS

This study aimed to test the hypothesis that the combined use of posterior augmented glenoid (PAG) implants with three-dimensional (3D) surgical planning and patient-specific instrumentation (PSI) guides helps reduce short-term PSH after aTSA in patients with type B2-B3 glenoids.

PATIENTS AND METHODS

We included nine consecutive patients with primary glenohumeral osteoarthritis and type B2 or B3 glenoids, who underwent aTSA with cemented keeled PAG implants (posterior augments of 15, 25, or 35 degrees). All patients underwent preoperative shoulder computed tomography (CT) scans, with 3D surgical planning coupled to PSI at the time of surgery. Postoperative shoulder CT scans were performed at an average of 14 weeks (range, 10-21 weeks). Scapulohumeral subluxation and glenoid version and inclination were measured in 3D, on both pre- and post-operative CT scans, using the same reliable quantitative method.

RESULTS

There was a significant decrease in scapulohumeral subluxation from 49±12% preoperatively to 22±17% postoperatively (p=0.0039), with a large effect size (Cohen's d=1.89). Preoperative glenoid version was corrected from -17.3±9.4 degrees to -5.2±7.5 degrees postoperatively. The absolute difference between the postoperative and surgically planned version and inclination was 5.4±3.6 degrees and 3.3±2.0 degrees, respectively.

DISCUSSION

The combined use of PAG implants with 3D preoperative planning and PSI results in a significant decrease in short-term PSH and glenoid version in patients with asymmetric posterior glenoid wear. We suggest that such implants should not be limited to posterior augmentation, because glenoid deficiency can also be observed in other glenoid sectors.

LEVEL OF EVIDENCE

IV, Basic science study.

Three-dimensional characterization of the anteverted glenoid (type D) in primary glenohumeral osteoarthritis

BACKGROUND

The Walch classification describes glenoid morphology in primary arthritis. As knowledge grows, several modifications to the classification have been proposed. The type D, a recent modification, was defined as an anteverted glenoid with or without anterior subluxation. Literature on the anteverted glenoid in primary osteoarthritis is limited. The purpose of this study, therefore, was to analyze the anatomic characteristics of the type D glenoid on radiographs and computed tomography (CT).

METHODS

The shoulder arthroplasty databases from 3 institutions were examined to identify patients with primary glenohumeral osteoarthritis and glenoid anteversion (≥5°), with or without anterior subluxation. The type D study cohort consisted of 18 patients (3% of the osteoarthritis cohort) and was a mean of 70 years old, with 11 women and 7 men. All radiographs were reviewed, and computed tomography Digital Imaging and Communications in Medicine (National Electrical Manufacturers Association, Rosslyn, VA, USA) data were analyzed on validated 3-dimensional imaging software. Rotator cuff fatty infiltration, glenoid measurements (anteversion and inclination), and humeral head subluxation according to the scapular plane were determined.

RESULTS

In the study cohort, the mean glenoid anteversion was 12° (range, 5°-24°), the mean inclination was 0°, and the mean anterior subluxation was 38% (range, 6%-56%). Eight patients (44%) had a biconcave glenoid with a posterosuperiorly positioned paleoglenoid and an anteroinferiorly positioned neoglenoid, and 10 patients had a monoconcave glenoid. Fatty infiltration of the rotator cuff muscles never exceeded Goutallier stage 2.

CONCLUSION

The type D glenoid is an addition to the original Walch classification and is characterized by glenoid anteversion (≥5°), anteroinferior humeral head subluxation, and absence of severe subscapularis fatty infiltration.