Aims. This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated. Methods. Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA). Results. Cartilage degeneration of the humeral head was associated with the histological presentation of: 1) pannus overgrowing the cartilage surface; 2) pores in the subchondral bone plate; and 3) chondrocyte clusters in OmA patients. In contrast, hyperplasia of the synovial lining layer was revealed as a significant indicator of inflammatory processes predominantly in CTA. The abundancy of collagen I, collagen II, and the C1,2C neoepitope correlated significantly with the histopathological degeneration of humeral head cartilage. No evidence for differences in MMP levels between OmA and CTA patients was found. Conclusion. This study provides a comprehensive histological characterization of humeral cartilage and synovial tissue within the glenohumeral joint, both in normal and diseased states. It highlights synovitis and pannus formation as histopathological hallmarks of OmA and CTA, indicating their roles as drivers of joint inflammation and cartilage degradation, and as targets for therapeutic strategies such as rotator cuff reconstruction and synovectomy. Cite this article: Bone Joint Res 2024;13(10):596–610

Introduction. For anatomical reconstruction in shoulder arthroplasty, it is important to understand normal glenohumeral geometry. Unfortunately, however, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. There is a racial difference in body size, and this difference probably results in a difference in glenohumeral size. The purpose of this study was to evaluate three-dimensional geometry of the glenohumeral joint in the normal Asian population and to clarify its morphologic features. Methods. Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy volunteers in age from 20 to 40 years. Using OsiriX MD, Geomagic Studio, and AVIZO software, the dimensions of humeral head width, humeral head diameter, glenoid height, glenoid width, and glenoid diameter were analyzed three-dimensionally (Figure 1). In diameter analyses, the humeral head was assumed to be a sphere and the glenoid was to fit a sphere (Figure 2–3). Sex differences in height, humeral length, humeral head width, humeral head diameter, glenoid height, glenoid width, and glenoid diameter were compared using Mann-Whitney U tests. The correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated with Spearman rank correlation tests. The significance level was set at 0.05 for all analyses. Results. Average height and humeral length of the volunteers were 164.7 ± 9.7 cm and 29.1 ± 1.8 cm respectively. The normal Asian glenohumeral joint has average humeral head width of 41.4 ± 3.7 mm, humeral head diameter of 42.9 ± 3.6 mm, glenoid height of 31.5 ± 2.8 mm, glenoid width of 23.1 ± 2.4 mm, and glenoid diameter of 62.0 ± 6.8 mm. The humeral head and glenoid were significantly larger in males than in females (p<0.001 in all analyses). The average radius difference between the glenoid and the humeral head was 9.6 ± 2.8 mm, and there was no sex difference (p=0.359). The average ratio of the glenoid radius to the humeral head radius was 144.9% ± 12.2%, and the ratio was significantly larger in females than in males (p=0.026). The glenohumeral size was well correlated between the two sides, and there were direct correlations among the heights, humeral length, humeral head size, and glenoid size (p<0.001 in all analyses). Conclusions. The present study revealed that the values of glenohumeral dimensions were uniform in both males and females with a strong correlation between the dominant shoulder and the nondominant shoulder. Since there are direct correlations among height, humeral length, and the size of the glenohumeral joint, we can also predict the glenohumeral size of patients from their respective heights. The present results would be useful to determine the size of implants and to improve clinical outcomes of shoulder arthroplasty for glenohumeral joints of Asian patients. The size of the Asian glenohumeral joint was obviously smaller than that reported in the past literature including black and Caucasian populations. Some shoulder prostheses that are designed in Europe or America and are widely used worldwide could be oversized for small females

Aims. Frozen shoulder is a common, painful condition that results in impairment of function. Corticosteroid injections are commonly used for frozen shoulder and can be given as glenohumeral joint (GHJ) injection or suprascapular nerve block (SSNB). Both injection types have been shown to significantly improve shoulder pain and range of motion. It is not currently known which is superior in terms of relieving patients’ symptoms. This is the protocol for a randomized clinical trial to investigate the clinical effectiveness of corticosteroid injection given as either a GHJ injection or SSNB. Methods. The Therapeutic Injections For Frozen Shoulder (TIFFS) study is a single centre, parallel, two-arm, randomized clinical trial. Participants will be allocated on a 1:1 basis to either a GHJ corticosteroid injection or SSNB. Participants in both trial arms will then receive physiotherapy as normal for frozen shoulder. The primary analysis will compare the Oxford Shoulder Score (OSS) at three months after injection. Secondary outcomes include OSS at six and 12 months, range of shoulder movement at three months, and Numeric Pain Rating Scale, abbreviated Disabilities of Arm, Shoulder and Hand score, and EuroQol five-level five-dimension health index at three months, six months, and one year after injection. A minimum of 40 patients will be recruited to obtain 80% power to detect a minimally important difference of ten points on the OSS between the groups at three months after injection. The study is registered under ClinicalTrials.gov with the identifier NCT04965376. Conclusion. The results of this trial will demonstrate if there is a difference in shoulder pain and function after GHJ injection or SSNB in patients with frozen shoulder. This will help provide effective treatment to patients with frozen shoulder. Cite this article: Bone Jt Open 2023;4(3):205–209

Summary. Analysis of existing data of patients who had undergone debridement procedure for osteoarthritis (OA) of glenohumeral joint showed improvement in disability at a minimum of one year following surgery. Injured workers were significantly younger and had a poorer outcome. Introduction. There is little information on debridement for OA of the shoulder joint. The purpose of this study was to examine factors that affect the outcome of arthroscopic debridement with or without acromioplasty /resection of clavicle of patients with osteoarthritis of the glenohumeral joint, in subjective perception of disability and functional range of motion and strength at a minimum of one year following surgery. Patients and Methods. Existing data of patients with advanced OA of the glenohumeral joint who had undergone debridement were used for analysis. These patients were not good candidates for shoulder arthroplasty due to a young age, high activity level, or desire to avoid major surgery at the time of assessment. Arthroscopic debridement included removal of loose bodies, chondral flaps, and degenerative tissue. Resection of the lateral end of the clavicle or acromioplasty was performed as clinically indicated for management of osteoarthritis of the Acromioclavicular (AC) joint or subacromial impingement respectively. Disability at a minimum of 12 months following surgery was measured by the American Shoulder and Elbow Surgeon's (ASES) assessment form, Constant-Murley score (CMS), strength, and painfree range of motion (ROM) in four directions. Impact of sex, age, having acromioplasty or resection of clavicle, and having an active work-related compensation claim was examined. Results. Seventy-four patients (mean age= 55, SD: 14 (range: 25–88), range: 35–86, 34 females, 40 males) were included in analysis. The average symptom duration was 5.8 years. Fifty nine (80%) patients had an associated subacromial decompression [55 (74%) had acromioplasty, 32(43%) had resection of the lateral end of the clavicle, and 28 (38%) had both procedures]. Nineteen (26%) patients had a work-related compensation claim related to their shoulder. This group was significantly younger than the non-compensation group (45 vs. 58, p=0.0001). Paired student t-tests showed a statistically significant improvement in scores of ASES and CMS (p<0.0001), strength (p=0.001) and painfree range of motion (p=0.01) at a minimum of 1 year follow-up. The ANCOVA model that incorporated sex, age, additional decompression (AC resection or acromioplasty), compensation claim and pre-op scores, showed that the pre-op scores and having a work-related claim were the most influential predictors of post-op scores of ASES, CMS, and ROM. The post-op strength was the only factor that was affected by sex, age and having a work-related claim. Discussion/Conclusion. Arthroscopic debridement with or without acromioplasty /resection of the lateral end of the clavicle improved disability, painfree range of motion and strength in patients suffering from osteoarthritis of glenohumeral joint at a minimum of one year following surgery. Patients with an active compensation claim related to their shoulder were significantly younger and had a poorer outcome

Purpose. There is minimal information on outcome of glenohumeral debridement for treatment of shoulder osteoarthritis (OA). The purpose of this study was to examine the outcome of this procedure with or without acromioplasty /resection of clavicle in subjective perception of disability and functional range of motion and strength at one year following surgery. Method. Prospectively collected data of patients with advanced OA of the glenohumeral joint who were not good candidates for shoulder arthroplasty due to young age, high activity level, or desire to avoid major surgery at the time of assessment were included. Arthroscopic debridement included removal of loose bodies, chondral flaps, and degenerative tissue. Resection of the lateral end of the clavicle or acromioplasty was performed as clinically indicated for management of osteoarthritis of the Acromioclavicular (AC) joint or subacromial impingement respectively. Disability at 12 months following surgery was measured by the American Shoulder and Elbow Surgeons (ASES) assessment form, Constant-Murley score (CMS), strength, and painfree range of motion in four directions. Results. Sixty-seven patients (mean age= 57, SD: 15 (range: 25–87), range: 35–86, 35 females, 32 males) were included in analysis. The average symptom duration was 5 years. Fifteen (22%) patients had left shoulder involvement with 37 (55%) having right shoulder problem and 15(22%) reporting bilateral complaints. The right shoulder was operated on in 41 (61%) patients. Fifty two (78%) patients had an associated subacromial decompression [49 (73%) had acromioplasty and 27 (40%) had resection of the lateral end of the clavicle with some procedures overlapping]. Paired student t-tests showed a statistically significant improvement in scores of ASES and CMS (p<0.001) and painfree range of motion (p=0.02) at 1 year follow-up. However, no change was observed in strength (p>0.05). Conclusion. Arthroscopic debridement with or without acromioplasty /resection of the lateral end of the clavicle improves disability and painfree range of motion in patients suffering from osteoarthritis of glenohumeral joint at one year following surgery

Aim. Biomechanical models of the shoulder have been used to measure forces and glenohumeral pressures. Their results have been found to vary. The aim of this study was to produce a biomechanical model to replicate the biomechanical principles of the glenohumeral joint and to measure the centre of pressure on the glenoid through a mid-range of arm movement with an intact and a compromised rotator cuff. Method. The model consisted of anatomic saw-bones of a scapula and proximal humerus with calibrated extension springs to mimic rotator cuff muscles. Glenoid pressures were measured using pressure sensitive film. The joint was examined through a mid-range of movement with an intact rotator cuff and a supraspinatus deficiency. Results. In the normal cuff model, in neutral, the centre of pressure was in the centre of the glenoid and migrated inferiorly on abduction, rotation and 45° of flexion. The only exception to this was 90° flexion and 35° extension. Concavity compression force rose in internal/external rotation, was steady on flexion/extension but dropped on abduction. In the supraspinatus-deficient model, the centre of pressure dropped to the inferior lip in neutral and rose on any movement with extremes of flexion and abduction, resulting in subacromial impingement. Concavity compression force rose slightly on flexion and extension. On abduction, the force rose as much as three times that of the normal cuff. Discussion. The results suggest that the humeral joint reaction force rests in the centre of the glenoid and is driven inferiorly on arm movement. Loss of supraspinatus reverses this pattern and leads to impingement. These results would be in keeping with osteoarthritic patterns in vivo and may have a bearing on glenoid prosthesis design. Conclusion. The glenohumeral joint demonstrated inferior migration of the humeral reaction force on elevation of the arm. Cuff pathology leads to breakdown of this mechanism

Purpose: Arthroscopic treatment of calcified tendinopathy is classically performed in two times: exploration of the glenohumeral joint followed by subacromial arthroscopy to evacuate the calcification. In our experience, glenohumeral arthroscopy has only exceptionally provided a diagnostic element. In addition, the principal complication of this procedure is retractile capsulitis which may be a secondary effect of glenohumeral aggression. We conducted a retrospective analysis to assess the effect of systematic exploration of the glenohumeral joint. Material and methods: Two homogeneous groups of patients were identified. Group 1 included 32 patients who had had glenohumeral arthroscopy then resection of the calcifications using a bursoscope. Group 2 included 32 patients whose treatment was limited to subacromial arthroscopy for resection. The preoperative Constant score (52 in group 1 and 54 in group 2), disease duration (34 and 40 months respectively), and localisation of the calcification were comparable for the two groups. Acromioplasty was not performed in these patients. All were reviewed at minimal follow-up of 6 months for assessment of the Constant score and a radiography study. Results: At last follow-up the mean Constant score was 70 in group 1; calcifications had disappeared in 84% of the cases and delay to recovery (total pain relief and return to work) was 11 months. There were 4 cases of postoperative capsulitis (12.5%). The mean Constant score was 79 in group 2; calcifications had disappeared in 78% of the cases and delay to recovery was 6.5 weeks (p = 0.0001). There was one case of retractile capsulitis (3%). In group 1, glenohu-meral arthroscopy did not lead to the discovery of specific elements except in two cases where it identified partial tear of the deep aspect of the supraspinatus. Acromioplasty was never performed. Discussion-Conclusion: Systematic glenohumeral arthros-copy is not warranted in patients undergoing treatment for calcified tendinopathy. The fact that glenohumeral exploration did not disclose any particular element and had no effect on healing and capsulitis rates favours the use of a subacromial approach alone

Aims: Although the glenohumeral joint is the most mobile articulation of the human body it is known to exhibit ball-and-socket-kinematics. Compression into the glenoid concavity keeps the humeral head centered. The purpose of this study was to determine the effects of joint position on glenohumeral stability through concavity-compression. Methods: Ten cadaver shoulders were tested. The glenoid was mounted horizontally onto a six-component load cell while the humerus was clamped to a vertically unconstrained slide. An x-y-stage translated the load cell with the glenoid underneath the humeral head in eight different directions. Compressive loads of twenty, forty and sixty Newtons were applied. The tests were repeated in 0, 30, 60 and 90 degrees of glenohumeral abduction with and without labrum. Translation distances and the forces resisting translation were recorded and the stability ratio calculated. Results: The average stability ratio was higher in hanging arm position than in glenohumeral abduction. With intact labrum the highest stability ratio was detected in inferior direction (59.8±7.7 percent), without labrum in superior direction (53.3±7.9 percent). In both conditions the anterior direction showed the lowest stability ratio (32.0±4.4 percent; 30.4±4.1 percent). Resection of the labrum resulted in a decrease in stability ratio of 9.6 ±1.7 percent. With increasing compressive load the stability ratio slightly decreased. Conclusions: Anterior shoulder dislocation may be facilitated by the lower stability in glenohumeral abduction and anterior direction. The labrum may not contribute as much as previously assumed to glenohumeral stability. Even moderate compressive forces are sufficient to provide stability through concavity-compression

Background. Acute anterior dislocation of the glenohumeral joint may be complicated by injury to neighboring structures. These injuries are best considered a spectrum of injury ranging from an isolated dislocation (unifocal injury), through injuries associated with either nerve or osteoligamentous injury (bifocal injury), to injuries where there is evidence of both nerve and osteoligamentous injury. The latter combination has previously been described as the “terrible triad,” although we prefer the term “trifocal,” recognizing that this is the more severe end of an injury spectrum and avoiding confusion with the terrible triad of the elbow. We evaluated the prevalence and risk factors for nerve and osteoligamentous injuries associated with an acute anterior glenohumeral dislocation in a large consecutive series of patients treated in our Unit. Materials and Methods. 3626 consecutive adults (mean age 48yrs) with primary traumatic anterior shoulder dislocation treated at our unit were included. All patients were interviewed and examined by an orthopaedic trauma surgeon and underwent radiological assessment within a week of injury. Where rotator cuff injury or radiologically-occult greater tuberosity fracture was suspected, urgent ultrasonography was used. Deficits in neurovascular function were assessed clinically, with electrophysiological testing reserved for equivocal cases. Results. Unifocal injuries occurred in 2228 (61.4%) of patients. There was a bimodal distribution in the prevalence of these injuries, with peaks in the 20–29 age cohort (34.4% patients) and after the age of 60 years (23.0% patients). Of the 1120 (30.9%) patients with bifocal dislocations, 920 (82.1%) patients had an associated osteotendinous injury and 200 (17.9%) patients had an associated nerve injury. Trifocal injuries occurred in 278 (7.7%) of cases. In bifocal and trifocal injuries, rotator cuff tears and fractures of the greater tuberosity or glenoid were the most frequent osteotendinous injuries. The axillary nerve was most frequently injured neurological structure. We were unable to elicit any significant statistical differences between bifocal and trifocal injuries with regards to patient demographics. However, when compared with unifocal injuries, bifocal or trifocal injuries were more likely to occur in older, female patients resulting from low energy falls (p<0.05). Conclusions. We present the largest series reporting the epidemiology of injury patterns related to traumatic anterior shoulder dislocation. Increased understanding and awareness of these injuries among clinicians will improve diagnosis and facilitate appropriate treatment

Purpose: 2 orthopaedic surgeons identified 18 patients who developed glenohumeral chondrolysis following arthroscopic shoulder surgery. The index surgery for all 18 patients occurred over an 18 month period. We sought to find any common factors among the 18 cases.

Method: A retrospective chart review of all 18 patients was performed. We gathered information on patient demographics, type of surgical procedure, nature of shoulder instability, post-operative complications such as infection, the use of radiofrequency energy, the type/number of suture anchors, the use of an IAPPC and the type of local anaesthetic used. We compared pre-operative radiographs and MRI scans to the intra-operative findings from the operative report to confirm that no chondrolysis was present pre-operatively. We examined post-operative radiographs and MRI scans to document the extent of chondrolysis

Results: Of the 18 patients who developed chondrolysis, we had 15 males and 3 females with an average age of 23 years (range 16–39). 17 patients had shoulder instability due to a definitive traumatic event while 1 patient had an atraumatic etiology. No radiofrequency energy was used in any of the cases. No post-operative infections were diagnosed and many had work-ups for infection which included ESR, CRP, bone & gallium/WBC scans. All patients had labral stabilization procedures, 15 anterior (Bankart), 1 posterior, and 2 combinations. All patients received suture anchors, 13 patients had 2 anchors and 5 had 3 anchors. 2 different manufacturer’s suture anchors were used, 10 patients received Smith & Nephew anchors while 8 patients received Linvatec anchors. 10 patients received bioabsorbable anchors and 8 patients received metal anchors. All patients received an IAPPC loaded with 0.5% bupivacaine with epinephrine for post-operative pain control. 15 of the IAPPC’s were considered large with an infusion rate of 5 mL/hr and a fill volume of 275 mL’s. 3 IAPPC’s were considered small with an infusion rate of 2 mL/hr and a fill volume of 100 mL’s.

Conclusion: We suspect a continuous intra-articular infusion of bupivacaine with epinephrine may have contributed to the development of chondrolysis. We caution against the use of IAPPC’s until their safety has been proven.

Introduction: Models of shoulder motion differ with intended application and shoulder models often simplify the complex movement. Therefore, the design often negates clinical usage, in which, for example, multidirectional instabilities are present. To aid the work of clinicians in treating articulations without simplifying physiological constraint, a full open-chain 6 Degrees Of Freedom per articulation has been suggested (Inui et al., 2002).

Aim: Develop a spatial linkage model in order to facilitate communication between surgeon and engineer, and to apply this model to image datasets.

Model Design: Modification of Grood and Suntay’s (1983) 3-cylinder open chain model of the Tibiofemoral articulation to faithfully determine spatial parameters throughout a large range of motion, about clinically relevant axes.

Method: A computer program was scripted (Matlab, Mathworks Inc.) to embed orthogonal coordinate frames in both Humerus and Scapula. These were specified in respect of the planes of clinical rotation and well defined anatomical landmarks. A floating axis was defined within the script as the bipolar common perpendicular to both fixed frames. The magnitude of relative rotations, α, β and γ – flexion, abduction and axial rotation respectively – between Scapula and Humeral frames are measured directly, whilst translations occur along the axis about which rotation is measured. Gimbal lock limitations were minimised.

Validation: A physical linkage was made to validate the computations resulting in further model modification to create continuous rotational data throughout the following range: α from −90° – 270°, β from −90° – 270° and γ from −180° – 180°. This model provided an iterative development and examination tool for enhancing the capabilities of the modelling program.

Application: The model was applied to functional images acquired from both Electron Beam Computed Tomography and MRI. Anatomical landmark coordinates were digitised and input into the customised software. The real-time output displays rotations and translations of the humerus relative to the scapula.

Conclusion: The model circumvents a rotational sequence dependent outcome by determining the joint displacements within the modelled system as independent of the order in which segmental translations and rotations occur: 2 axes are fixed within articulating segments, whist a third mutually perpendicular floating axis moves in relation to both. The method facilitates multi-disciplinary communication: the parameters have a rigorous mathematical description and they correspond to clinical measures of position and orientation. Finally, this method accounts for Codman’s paradox with geometric principles.

Synovitis in the subacromial bursa (SAB) and the gle-nohumeral joint (GHJ) is often seen in rotator cuff diseases. In order to clarify its significance, following studies were conducted. The mRNA expression levels of IL-1B, sIL-1ra and icIL-1ra and the amount of substance P in the SAB synovium were correlated with the degree of shoulder pain. The cytokine-mRNAs in the GHJ synovium expressed more significantly in full-thickness tears (perforating tears) than in non-perforating tears. Biochemical markers (MMP-1, MMP-3) in the GHJ fluid were significantly higher in massive cuff tears than in smaller tears. These findings suggest the possibility that SAB and GHJ synovitis in rotator cuff diseases are associated with shoulder pain and the development of glenohumeral arthropathy, respectively.

Aims. Shoulder arthroplasty is effective in the management of end-stage glenohumeral joint arthritis. However, it is major surgery and patients must balance multiple factors when considering the procedure. An understanding of patients’ decision-making processes may facilitate greater support of those considering shoulder arthroplasty and inform the outcomes of future research. Methods. Participants were recruited from waiting lists of three consultant upper limb surgeons across two NHS hospitals. Semi-structured interviews were conducted with 12 participants who were awaiting elective shoulder arthroplasty. Transcribed interviews were analyzed using a grounded theory approach. Systematic coding was performed; initial codes were categorized and further developed into summary narratives through a process of discussion and refinement. Data collection and analyses continued until thematic saturation was reached. Results. Two overall categories emerged: the motivations to consider surgery, and the information participants used to inform their decision-making. Motivations were, broadly, the relief of pain and the opportunity to get on with life and regain independence. When participants’ symptoms and restrictions prevented them enjoying life to a sufficient extent, this provided the motivation to proceed with surgery. Younger participants tended to focus on maintaining employment and recreational activities, and older patients were eager to make the most of their remaining lifetime. Participants gathered information from a range of sources and were keen to optimize their recovery where possible. An important factor for participants was whether they trusted their surgeon and were prepared to delegate responsibility for elements of their care. Conclusion. Relief of pain and the opportunity to get on with life were the primary reasons to undergo shoulder arthroplasty. Participants highlighted the importance of the patient-surgeon relationship and the need for accurate information in an accessible format which is relevant to people of different ages and functional demands. Cite this article: Bone Jt Open 2024;5(7):543–549

Abstract. Objective. Radial to axillary nerve and spinal accessory (XI) to suprascapular nerve (SSN) transfers are standard procedures to restore function after C5 brachial plexus dysfunction. The anterior approach to the SSN may miss concomitant pathology at the suprascapular notch and sacrifices lateral trapezius function, resulting in poor restoration of shoulder external rotation. A posterior approach allows decompression and visualisation of the SSN at the notch and distal coaptation of the medial XI branch. The medial triceps has a double fascicle structure that may be coapted to both the anterior and posterior division of the axillary nerve, whilst preserving the stabilising effect of the long head of triceps at the glenohumeral joint. Reinnervation of two shoulder abductors and two external rotators may confer advantages over previous approaches with improved external rotation range of motion and strength. Methods. Review of the clinical outcomes of 22 patients who underwent a double nerve transfer from XI and radial nerves. Motor strength was evaluated using the MRC scale and grade 4 was defined as the threshold for success. Results. 18/22 patients had adequate follow-up (Mean: 29.5 months). Of these, 72.2% achieved ≥grade 4 power of shoulder abduction and a mean range of motion of 103°. 64.7% achieved ≥grade 4 external rotation with a mean range of motion of 99.6°. Conclusions. The results suggest the use of the combined nerve transfer for restoration of shoulder function via a posterior approach, involving the medial head branch of triceps to the axillary nerve and the XI to SSN

Glenohumeral joint injuries frequently result in shoulder instability. However, the biomechanical effect of cartilage loss on shoulder stability remains unknown. The aim of the current study was to investigate biomechanically the effect of two severity stages of cartilage loss in different dislocation directions on shoulder stability. Joint dislocation was provoked for 11 human cadaveric glenoids in seven different dislocation directions between 3 o'clock (anterior) to 9 o'clock (posterior) dislocation. Shoulder stability ratio (SSR) and concavity gradient were assessed in intact condition, and after 3 mm and 6 mm simulated cartilage loss. The influence of cartilage loss on SSR and concavity gradient was statistically evaluated. Between intact state and 6 mm cartilage loss, both SSR and concavity gradient decreased significantly in every dislocation direction (p≤0.038), except the concavity gradient in 4 o'clock dislocation direction (p=0.088). Thereby, anterior-inferior dislocation directions were associated with the highest loss of SSR and concavity gradient of up to 59.0% and 49.4%, respectively, being significantly higher for SSR compared to all other dislocation directions (p≤0.04). The correlations between concavity gradient and SSR for pooled dislocation directions were significant for all three conditions of cartilage loss (p<0.001). From a biomechanical perspective, articular cartilage of the glenoid contributes significantly to the concavity gradient, correlating strongly with the associated loss in glenohumeral joint stability. The highest effect of cartilage loss was observed in anterior-inferior dislocation directions, suggesting that surgical intervention should be considered for recurrent shoulder dislocations in the presence of cartilage loss

Aim. Clavicular osteotomy was described as an adjunct to deltopectoral approach for improved exposure of the glenohumeral joint. This study aims to present contemporary outcomes and complications associated with the routine use of clavicular osteotomy by a single surgeon in a regional setting within New Zealand. Methods. A retrospective case series of patients who have undergone any shoulder arthroplasty for any indication between March 2017 to August 2022. This time period includes all patients who had clavicular osteotomy(OS) and patients over an equal time period prior to the routine use of osteotomy as a reference group (N-OS). Oxford Shoulder Score (OSS) and a Simple Shoulder Test (STT) were used to assess functional outcomes and were compared with the reported literature. Operative times and Complications were reviewed. Results. 66 patients were included in the study. 33 patients in the OS group and 33 in the N-OS group. No difference in age, sex, indications for operative intervention and the surgery provided was identified. No significant difference in operative time between groups (N-OS 121 minutes; OS 128 minutes). No clinically significant difference was identified in the OSS (N-OS; mean 38 vs OS 39) or the STT (N-OS 8.3 vs OS 9). The outcomes scores of both groups are in keeping with published literature. Two post operative clavicle fractures, one prominent surgical knot occurred in the OS that required further surgical intervention. Two cases of localized pain over the clavicle and one case of the prominent lateral clavicle were reported in the OS group. Two cases of localized pain over clavicle reported in the N-OS group. Conclusion. Use of clavicular osteotomy is not associated with inferior patient reported. The osteotomy introduces specific risks, however, the study provides evidence that these complications are infrequent and avoidable. Surgeons should feel confident in using this adjunct when exposure to the shoulder is difficult

To analyse bone stresses in humerus-megaprosthesis construct in response to axial loading under varying implant lengths in proximal humeral replacement following tumour excision. CT scans of 10 cadaveric humeri were processed in 3D Slicer to obtain three-dimensional (3D) models of the cortical and cancellous bone. Megaprostheses of varying body lengths (L) were modelled in FreeCAD to obtain the 3D geometry. Four FE models: group A consisting of intact bone; groups B (L=40mm), C (L=100mm) and D (L=120mm) comprising of humerus-megaprosthesis constructs were created. Isotropic linear elastic behaviour was assigned for all materials. A tensile load of 200N was applied to the elbow joint surface with the glenohumeral joint fixed with fully bonded contact interfaces. Static analysis was performed in Abaqus. The bone was divided at every 5% bone length beginning distally. Statistical analysis was performed on maximum von Mises stresses in cortical and cancellous bone across each slice using one-way ANOVA (0-45% bone length) and paired t-tests (45-70% bone length). To quantify extent of stress shielding, average percentage change in stress from intact bone was also computed. Maximum stress was seen to occur distally and anteriorly above the coronoid fossa. Results indicated statistically significant differences between intact state and shorter megaprostheses relative to longer megaprostheses and proximally between intact and implanted bones. Varying levels of stress shielding were recorded across multiple slices for all megaprosthesis lengths. The degree of stress shielding increased with implant lengthening being 2-4 times in C and D compared to B. Axial loading of the humerus can occur with direct loading on outstretched upper limbs or indirectly through the elbow. Resultant stress shielding effect predicted in longer megaprosthesis models may become clinically relevant in repetitive axial loading during activities of daily living. It is recommended to use shorter megaprosthesis to prevent failure

Aim. Deadspace is the tissue and bony defect in a surgical wound after closure. This space is presumably poorly perfused favouring bacterial proliferation and biofilm formation. In arthroplasty surgery, an obligate deadspace surrounding the prosthesis is introduced and deadspace management, in combination with obtaining therapeutic prophylactic antibiotic concentrations, is important for limiting the risk of acquiring a periprosthetic joint infection (PJI). This study aimed to investigate cefuroxime distribution to an orthopaedic surgical deadspace in comparison with plasma and bone concentrations during two dosing intervals (8 h × 2). Method. In a setup imitating shoulder arthroplasty surgery, but without insertion of a prosthesis, microdialysis catheters were placed for cefuroxime sampling in a deadspace in the glenohumeral joint and in cancellous bone of the scapular neck in eighteen pigs. Blood samples were collected from a central venous catheter as a reference. Cefuroxime was administered according to weight (20 mg/kg). The primary endpoint was time above the cefuroxime minimal inhibitory concentration of the free fraction of cefuroxime for Staphylococcus aureus (fT > MIC (4 µg/mL)). Results. During the two dosing intervals, mean fT > MIC (4 µg/mL) was significantly longer in deadspace (605 min) compared with plasma (284 min) and bone (334 min). For deadspace, the mean time to reach 4 µg/mL was prolonged from the first dosing interval (8 min) to the second dosing interval (21 min), while the peak drug concentration was lower and half-life was longer in the second dosing interval. Conclusions. In conclusion, weight-adjusted cefuroxime fT > MIC (4 µg/mL) and elimination from the deadspace was longer in comparison to plasma and bone. Our results suggest a deadspace consolidation and a longer diffusions distance, resulting in a low cefuroxime turn-over. Based on theoretical targets, cefuroxime appears to be an appropriate prophylactic drug for the prevention of PJI. Acknowledgments. We would like to thank Department of Clinical Medicine, the surgical research laboratories, Aarhus University Hospital and Department of Clinical Biochemistry, Lillebaelt Hospital, Vejle, Denmark, for supporting this study. This research was funded by Novo Nordisk Foundation, grant number [NNF20OC0062032, 2020]

Magnetic resonance imaging (MRI) is the gold standard for the diagnosis of the pathologies affecting the glenohumeral joint and the rotator cuff diseases. MRI allows to highlight anatomic discontinuities of both muscles and tendons. However, MRI diagnostic accuracy has not proven to be highly sensitive in distinguishing between a partial-thickness tear and a full-thickness rotator cuff tear. The purpose of this study was to determine if MRI under axial traction can be helpful in increasing MRI sensitivity to identify partial-thickness rotator cuff tears. The study included 10 patients (4 males and 6 females) who had clinical examination and MRI suggesting a partial-thickness rotator cuff tear. They were candidates for shoulder arthroscopy because of persistent symptoms after at least three months of conservative treatment. The patients underwent a new MRI (under axial traction: MRI-AT) with a 4-kg weight applied to the affected arm. Then the patients underwent arthroscopy to confirm the diagnosis. Patients with a suspected full-thickness rotator cuff tear were excluded from the study. Patients’ average age was 52.4 years, and the dominant side was affected in 77.7% of the cases. Preoperative Constant-Murley Score was 57. MRI-AT showed that 3 patients were affected by a complete tear of the rotator cuff, 3 patients by a partial-thickness rotator cuff tear and 4 patients had no lesion. The analysis of data showed that: under axial traction the subacromial space increased by 0,2 mm (P value = 0,001075), the superior glenohumeral space decreased by 2.4 mm (P value = 0,07414), the inferior glenohumeral space increased by 0.3 mm (P value = 0,02942), the acromial angle decreased by 1.9° (P value = 0,0002104) and the acromion-glenohumeral angle decreased by 0.3° (P-value = 0,01974). Two experienced evaluators analyzed previous standard MRI and MRI-AT scans in a double-blinded fashion, with inter-rater evaluation of all the images and measures. Intraclass correlation coefficient (ICC) has been utilized to assess the reliability of the measures performed by different operators. ICC always resulted in more than 0.7, showing a high concordance among values in the same group. A comparative evaluation between standard MRI and MRI-AT has been conducted to highlight possible discrepancies and this has been compared to intraoperative findings. Concordance of the values was 89% between standard MRI and MRI-AT and 100% between MRI under axial traction and intraoperative findings. This study showed a high correlation between the diagnosis achieved with MRI-AT and the intraoperative arthroscopic findings. The use of MRI-AT in clinical practice may improve the diagnostic sensitivity of this method to detect a partial-thickness rotator cuff tear

Analyzing shoulder kinematics is challenging as the shoulder is comprised of a complex group of multiple highly mobile joints. Unlike at the elbow or knee which has a primary flexion/extension axis, both primary shoulder joints (glenohumeral and scapulothoracic) have a large range of motion (ROM) in all three directions. As such, there are six degrees of freedom (DoF) in the shoulder joints (three translations and three rotations), and all these parameters need to be defined to fully describe shoulder motion. Despite the importance of glenohumeral and scapulothoracic coordination, it's the glenohumeral joint that is most studied in the shoulder. Additionally, the limited research on the scapulothoracic primarily focuses on planar motion such as abduction or flexion. However, more complex motions, such as internally rotating to the back, are rarely studied despite the importance for activities of daily living. A technique for analyzing shoulder kinematics which uses 4DCT has been developed and validated and will be used to conduct analysis. The objective of this study is to characterize glenohumeral and scapulothoracic motion during active internal rotation to the back, in a healthy young population, using a novel 4DCT approach. Eight male participants over 18 with a healthy shoulder ROM were recruited. For the dynamic scan, participants performed internal rotation to the back. For this motion, the hand starts on the abdomen and is moved around the torso up the back as far as possible, unconstrained to examine variability in motion pathway. Bone models were made from the dynamic scans and registered to neutral models, from a static scan, to calculate six DoF kinematics. The resultant kinematic pathways measured over the entire motion were used to calculate the ROM for each DoF. Results indicate that anterior tilting is the most important DoF of the scapula, the participants all followed similar paths with low variation. Conversely, it appears that protraction/retraction of the scapula is not as important for internally rotating to the back; not only was the ROM the lowest, but the pathways had the highest variation between participants. Regarding glenohumeral motion, internal rotation was by far the DoF with the highest ROM, but there was also high variation in the pathways. Summation of ROM values revealed an average glenohumeral to scapulothoracic ratio of 1.8:1, closely matching the common 2:1 ratio other studies have measured during abduction. Due to the unconstrained nature of the motion, the complex relationship between the glenohumeral and scapulothoracic joints leads to high variation in kinematic pathways. The shoulder has redundant degrees of freedom, the same end position can result from different joint angles and positions. Therefore, some individuals might rely more on scapular motion while others might utilize primarily humeral motion to achieve a specific movement. More analysis needs to be done to identify if any direct correlations can be drawn between scapulothoracic and glenohumeral DoF. Analyzing the kinematics of the glenohumeral and scapulothoracic joint throughout motion will further improve understanding of shoulder mechanics and future work plans to examine differences with age