Background. Rotator cuff atrophy evaluated with computed tomography scans has been associated with asymmetric glenoid wear and humeral head subluxation in glenohumeral arthritis. Magnetic resonance imaging has increased sensitivity for identifying rotator cuff pathology and has not been used to investigate this relationship. The purpose of this study was to use MRI to assess the association of rotator cuff muscle atrophy and glenoid morphology in primary glenohumeral arthritis. Methods. 132 shoulders from 129 patients with primary GHOA were retrospectively reviewed and basic demographic information was collected. All patients had MRIs that included appropriate orthogonal imaging to assess glenoid morphology and rotator cuff pathology and were reviewed by two senior surgeons. All patients had intact rotator cuff tendons. Glenoid morphology was assigned using the modified-Walch classification system (types A1, A2, B1, B2, B3, C, and D) and rotator cuff fatty infiltration was assigned using Goutallier scores. Results. 46 (35%) of the shoulders had posterior wear patterns (23 type B2s, 23 type B3s). Both the infraspinatus and teres minor independently had significantly more fatty infiltration in B2 and B3 type glenoids compared to type A glenoids (p<0.001). There was a greater imbalance in posterior rotator cuff muscle fatty atrophy in B2 and B3 type glenoids compared to type A glenoids (p<0.001). However, there was no difference in axial plane imbalance between B2 and B3 glenoids (p=1.00). There was increased amount fatty infiltration of the infraspinatus among B2 and B3-type glenoids compared to type A glenoids on multivariate analysis controlling for age and gender (p<0.001). Conclusions. These results identify significant axial plane rotator cuff muscle imbalances in B2 and B3-type glenoids compared to concentrically worn glenoids, favoring a relative increase in fatty infiltration of the infraspinatus and teres minor compared to the subscapularis in glenoids with patterns of posterior wear. For any figures or tables, please contact authors directly

Background. Malposition of the glenoid component in total shoulder arthroplasty (TSA) is associated with higher strain patterns and can result in component loosening. Glenoid hardware placement and optimal size remain challenging due to the difficult joint exposure and visualization of anatomical reference landmarks during the procedure. Therefore, understanding both normal and variant patterns of glenoid anatomy is imperative for success in TSA. To better understand individual variations in glenoid morphology, this study aimed to compare the glenoid anatomy in a cohort of male and female patients from the United States (US) and Australia (AUS). Methods. Computed tomography (CT) data were analyzed from 41 male and 35 female shoulders; 39 of which were from a US population and 37 from an AUS population. These data were used to create statistical shape models (SSM) representing the average and ±1 standard deviations of the first mode of variation of each group (Materialise, Leuven, Belgium). All measurements were performed with 3-matic computer assisted design software (Materialise, Leuven, Belgium). On each model, glenoid height was measured as the distance from the most superior to the most inferior point on the glenoid face. Glenoid width was measured as the distance from the most anterior to the most posterior point on the glenoid face. Surface area was measured as the concave surface of the glenoid face (Figure 1). Glenoid vault depth was measured in the midsection of the glenoid face. Results. The overall glenoid dimensions were similar between AUS and US populations with average SSMs having widths of 24.68 and 25.72mm, heights of 34.63 mm and 34.85 mm, vault depths of 31.81 mm and 30.20 mm, and surface areas of 665.8 mm2 and 659.2 mm2 (Figure 2). All measurements were also similar for sex matched SSMs (Figure 3). We did observe differences between males and females within these populations, with males in general having larger glenoids in all parameters measured but the greatest difference was seen in surface area. Discussion. Our findings indicate that glenoid morphology is similar between these populations. This supports the external validity of previous studies of glenoid anatomy in these populations, and the use of similar implants between these groups. The gender differences observed in this study reflect previously reported differences. Interestingly, the glenoid depths were greater than the length of most commercial glenoid pegs (14–20 mm) or RSA screws (15–30 mm), indicating that implant perforation of the glenoid vault is unlikely if surgeons properly place and select appropriate sized glenoid implants in either population

Glenoid baseplate positioning for reverse total shoulder replacements (rTSR) is key for stability and longevity. 3D planning and image-derived instrumentation (IDI) are techniques for improving implant placement accuracy. This is a single-blinded randomised controlled trial comparing 3D planning with IDI jigs versus 3D planning with conventional instrumentation. Eligible patients were enrolled and had 3D pre-operative planning. They were randomised to either IDI or conventional instrumentation; then underwent their rTSR. 6 weeks post operatively, a CT scan was performed and blinded assessors measured the accuracy of glenoid baseplate position relative to the pre-operative plan. 47 patients were included: 24 with IDI and 23 with conventional instrumentation. The IDI group were more likely to have a guidewire placement within 2mm of the preoperative plan in the superior/inferior plane when compared to the conventional group (p=0.01). The IDI group had a smaller degree of error when the native glenoid retroversion was >10° (p=0.047) when compared to the conventional group. All other parameters (inclination, anterior/posterior plane, glenoids with retroversion <10°) showed no significant difference between the two groups. Both IDI and conventional methods for rTSA placement are very accurate. However, IDI is more accurate for complex glenoid morphology and placement in the superior-inferior plane. Clinically, these two parameters are important and may prevent long term complications of scapular notching or glenoid baseplate loosening. Image-derived instrumentation (IDI) is significantly more accurate in glenoid component placement in the superior/inferior plane compared to conventional instrumentation when using 3D pre-operative planning. Additionally, in complex glenoid morphologies where the native retroversion is >10°, IDI has improved accuracy in glenoid placement compared to conventional instrumentation. IDI is an accurate method for glenoid guidewire and component placement in rTSA

In patients with shoulder arthritis, the ability to accurately determine glenoid morphological alterations affects the outcomes of shoulder arthroplasty surgery significantly. This study was conducted to determine whether there is a correlation between scapular and glenoid morphometric components. Existence of such a correlation may help surgeons accurately estimate glenoid bone loss during pre-operative planning. The dimensions and geometric relationships of the scapula, scapula apophysis and glenoid were assessed using CT scan images of 37 South African and 40 Chinese cadavers. Various anatomical landmarks were marked on the 77 scapulae and a custom script was developed to perform the measurements. Intra-cohort correlation and inter-cohort differences were statistically analysed using IBM SPSS v28. The condition for statistical significance was p<0.05. The glenoid width and height were found to be significantly (p<0.05) correlated with superior glenoid to acromion tip distance, scapula height, acromion tip to acromion angle distance, acromion width, scapula width, and coracoid width, in both the cohorts. While anterior glenoid to coracoid tip distance was found to be significantly correlated to glenoid height and width in the South African cohort, it was only significantly correlated to glenoid height in the Chinese cohort. Significant (p<0.05) inter-cohort differences were observed for coracoid height, coracoid width, glenoid width, scapula width, superior glenoid to acromion tip distance, and anterior glenoid to coracoid tip distance. This study found correlations between the scapula apophyseal and glenoid measurements in the population groups studied. These morphometric correlations can be used to estimate the quantity of bone loss in shoulder arthroplasty patients

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

Glenoid bone loss is not an uncommon challenge in both primary shoulder arthroplasty surgery and revision surgery. Walch described the classification of glenoid morphology and this has led to an understanding of the expanded role for bone grafting, patient-specific implants and reverse prostheses. While bone grafting of the glenoid in conventional arthroplasty has been shown to be successful in some patients it is more routinely used in combination with reverse prostheses. More recently, augmented glenoid components have been developed for both conventional and reverse arthroplasty, though follow-up is insufficient to confirm their durability at this time

Purpose of study:. Reverse shoulder arthroplasty is effective in the management of symptomatic arthritic shoulders with a non-reconstructable rotator cuff. Optimal orientation and initial fixation of the glenoid component is correlated with improved outcomes. This may be difficult to achieve with distorted glenoid morphology. The authors present a previously undescribed system for accurate, consistent and reliable screw placement for fixation of the glenoid component with the desired version during reverse shoulder arthroplasty. Description of methods:. The pre-operative CT scan images are used to construct a scapula model (Medical Image Processing software, CustomMed Orthopaedics)allowing the surgeon to determine the optimal position for screw placement based on available bone stock. A custom drill guide is made from polyamide, which is sterilized in an autoclave and fitted to the glenoid intra-operatively prior to reaming. The system minimizes the likelihood of malposition of glenoid components and is compatible with all arthroplasty systems. Summary of results:. The technique has been performed on 5 patients after informed consent. Post-operative CT images demonstrate intended component version and screw position in all cases. Patients are being recruited for a multicenter prospective trial. Conclusion:. The authors present a new technique for achieving optimal screw position in fixation of glenoid components. A prospective trial is underway which aims to prove through post-operative imaging that intended glenoid version and screw placement was achieved and show improved long term results

Background and Motivation. Accurate placement of glenoid components in reverse and total shoulder arthroplasty has been shown to reduce the risk of implant failure (1, 2, 6). Surgical techniques and literature describe methods to determine favorable positions for implant placement (3, 4, 5) but achieving that position surgically remains a challenge. Placement of glenoid components is faced with the challenge of variable glenoid morphology on which conventional instrumentation does not always provide a reliable reference (6, 7, 8). Limited surgical exposure is another challenge since many anatomic landmarks are not visible to the surgeon to use as spacial reference. Anatomic landmarks and angles can be more reliabily selected on CT scans with 3-dimentional reconstruction (9,10) yet few methods allow for the reproducible translation of these plans to surgery. Navigation has produced better accuracy and lower variability than conventional instrumentation (11), yet its regular usage remains limited, especially in the shoulder. Methods. A patient specific planning and guiding system has been developed for glenoid implant placement of total and reverse shoulder arthoplasty procedures. This method allows for preoperative planning on a patient specific virtual 3D model of the scapula derived from CT images (Figure 1), and guided placement of a pin which which serves as the central axis for determining proper implant position. An initial implant position was presented on the virtual model based on the methods described by the surgical technique of the corresponding procedure. These plans were either approved or adapted to a desired position within the planning software by the surgeons. Using this planned position as input, patient specific surgical guides were created which fit onto the exposed anatomy and guide the drilling of the pin (Figure 1). This method was tested on 14 cadavers, with attention directed to translation of the starting point from the original plan, the ability to reproduce the intended degree of inferior tilt, and the ability to reproduce the glenoid version angle. Results. The ability to reproduce the surgical plan was found to be highly accurate for the 14 cadaveric specimens. Translational accuracy amongst the 14 cadavers was found to be 1.01 ± 0.53 mm, tilt was 0.46 ± 0.53 degrees, and the accuracy of version was found to be 1.16 degrees ± 1.15 degrees. Conclusion. Surgical planning on patient specific virtual bone models and the corresponding surface matched drilling guides for glenoid implant positiong provide surgeons with an accurate method to achieve the desired surgical implant position. The measured accuracy compares favorably to both conventional and navigated techniques

Background. The Copeland shoulder resurfacing arthroplasty (CSRA) (Figure1) is a cementless, pegged humeral head surface replacement which has been in clinical use since 1986. The indications for CSRA are more or less the same as conventional stemmed arthroplasty. This procedure can be considered for all patients who require shoulder replacement due to GHJ arthritis resulted from primary or secondary OA, RA, and other variations of inflammatory arthritis. It is also suggested as the first choice option for relatively young patients with post-traumatic arthritis, avascular necrosis (AVN), and instability arthropathy. This observational study reports functional and radiological outcome in CSRA during 4 years follow-up. Methods. 109 consecutive patients with primary osteoarthritis (45.9%), rheumatoid arthritis (39.4%), rotator cuff arthropathy (9.2%), and avascular necrosis (5.5%) underwent CSRA. Patients including 68 females (63%) and 41 males (37%) underwent this procedure (63 right-sided and 46 left-sided including 9 bilateral shoulders). The outcome assessment included pain and satisfaction, Oxford Shoulder Score (OSS), Constant Score (CS), and SF-12. Imaging was reviewed for glenoid morphology (Walch classification) (Figure2) and humeral head migration. The average follow-up period was 4 years, (range: 1 to 10 years). Results. Primary OA and RA were the most common underlying pathologies in 45.9% and 39.4% of patients, respectively, followed by RCA (9.2%) and AVN (5.5%). Approximately 89% of arthroplasties were primary and 11% were revisions. Other body joints were affected in 85% of patients and nearly 70% of them had accompanying health conditions and co-morbidities (e.g. heart diseases, hypertension, and diabetes mellitus). A strong correlation found for OSS regarding CS and physical SF-12 subscale. Pain and physical limitation had negative correlation with satisfaction and shoulder-specific tools. Walch type A (68%) and superior HH migration (16.8%) were the commonest radiographic presentations. There was high correlation between migration and physical limitation, pain, satisfaction, OSS, and CS. A significant difference noted for OSS, CS, physical limitation, pain and satisfaction between migration and non-migration groups. Discussion. The CSRA provides pain relief and a good functional outcome in many patients. The main disadvantage is the technical difficult of implanting a glenoid which many surgeons now perceive as being essential in order to gain early pain relief and a better functional outcome. Our results show a predictable relationship between outcome and pathology, with osteoarthritic patients having the most favourable outcome. Glenoid wear and cuff related problems are the major reasons for failure. Improvements in the design and surgical technique to reduce the likelihood of HH migration remain the major challenge. CSRA should be considered the implant of choice in younger patients with osteoarthritis and RA where there is concern over conserving bone stock for future revision. Considering the nature of underlying pathologies it is appropriate to use a combination of generic and shoulder-specific outcome tools

Introduction:. Subchondral bone density (SBD) distribution is an important parameter regarding that may be important when considering implant stability. This parameter is a reflection of the loading experienced by the joint throughout the lifetime and may be useful in pre-surgical planning and implant design. Clinically, the question of the glenoid surface preparation for TSA/RSA remains controversial, despite numerous published studies on glenoid bone morphology. To address this question, there exists a need to develop a 3D quantitative method capable of analyzing the complex glenoid bone morphology at different depths from the surface. Computed tomographic osteoabsoptiomery (CT-OAM) evaluates SBD based on the Housfield Unit (HU) value of each pixel. In this pilot study, we aimed to analyze SBD distribution of the glenoid at different depths by means of CT-OAM in male TSA subjects. Materials and Methods:. A study group of twenty male TSA patients (61–69y.o) were included in this study. Each subject obtained a pre-operative CT scan following a standardized protocol on the same CT scanner (1.25 mm slice thickness). Resultant DICOM 2D images were processed in custom-written program (VC++) and the surface of every glenoid was manually traced from the axial slices. Care was taken during the manual tracing process to exclude osteophytes and cyst formations from the resultant surface. Values of HU at every selected pixel on the surface of the glenoid were recorded. Subsequently, the layer of pixels at a 0.5 mm distance from the previous surface was virtually scraped and the HU values of new layer of pixels were recorded. This routine was repeated up to a depth of 5 mm from the glenoid surface, taking measurements on 11 virtual 3D surfaces with a thickness of 0.5 mm. Mean SBD distribution was reported for each layer and differences were compared using ANOVA and Fisher's post-hoc test. Results:. Apparent differences in mean SBD distribution were identified at every measured depth from the glenoid surface (Fig. 1). Significant differences (Tab.1) were identified between the middle range of studied surfaces (2.5–4.5 mm) when compared to the superficial (0–1.5 mm, p < 0.0001) and deep layers (5 mm, p < 0.0001). The maximum mean value of HU (1635.9 ± 35.5) was measured at 3.5 mm depth and the minimum value of HU was measured on the surface of the glenoid (1445.8 ± 31.3). Discussion:. The stability of the glenoid component in TSA prostheses is highly dependent on the SBD distribution. Controversy among orthopaedic surgeons exists regarding the depth of reaming required to prepare an arthritic glenoid. Extensive reaming may lead to the violation of the support provided by the denser subchondral bone; however, optimal match between the bone and glenoid component undersurface is highly desirable. This study demonstrates that the density of the bone is sustained up to a depth of approximately 4.5 mm from the glenoid surface, suggesting that an increased reaming may be favorable without compromising bony support