Healthy Shoulders Research Articles

Detection, classification, and characterization of proximal humerus fractures on plain radiographs.

The purpose of this study was to develop a convolutional neural network (CNN) for fracture detection, classification, and identification of greater tuberosity displacement ≥ 1 cm, neck-shaft angle (NSA) ≤ 100°, shaft translation, and articular fracture involvement, on plain radiographs. The CNN was trained and tested on radiographs sourced from 11 hospitals in Australia and externally validated on radiographs from the Netherlands. Each radiograph was paired with corresponding CT scans to serve as the reference standard based on dual independent evaluation by trained researchers and attending orthopaedic surgeons. Presence of a fracture, classification (non- to minimally displaced; two-part, multipart, and glenohumeral dislocation), and four characteristics were determined on 2D and 3D CT scans and subsequently allocated to each series of radiographs. Fracture characteristics included greater tuberosity displacement ≥ 1 cm, NSA ≤ 100°, shaft translation (0% to < 75%, 75% to 95%, > 95%), and the extent of articular involvement (0% to < 15%, 15% to 35%, or > 35%). For detection and classification, the algorithm was trained on 1,709 radiographs (n = 803), tested on 567 radiographs (n = 244), and subsequently externally validated on 535 radiographs (n = 227). For characterization, healthy shoulders and glenohumeral dislocation were excluded. The overall accuracy for fracture detection was 94% (area under the receiver operating characteristic curve (AUC) = 0.98) and for classification 78% (AUC 0.68 to 0.93). Accuracy to detect greater tuberosity fracture displacement ≥ 1 cm was 35.0% (AUC 0.57). The CNN did not recognize NSAs ≤ 100° (AUC 0.42), nor fractures with ≥ 75% shaft translation (AUC 0.51 to 0.53), or with ≥ 15% articular involvement (AUC 0.48 to 0.49). For all objectives, the model's performance on the external dataset showed similar accuracy levels. CNNs proficiently rule out proximal humerus fractures on plain radiographs. Despite rigorous training methodology based on CT imaging with multi-rater consensus to serve as the reference standard, artificial intelligence-driven classification is insufficient for clinical implementation. The CNN exhibited poor diagnostic ability to detect greater tuberosity displacement ≥ 1 cm and failed to identify NSAs ≤ 100°, shaft translations, or articular fractures.

Microwave Digital Twin Prototype for Shoulder Injury Detection.

One of the most common shoulder injuries is the rotator cuff tear (RCT). The risk of RCTs increases with age, with a prevalence of 9.7% in those under 20 years old and up to 62% in individuals aged 80 years and older. In this article, we present first a microwave digital twin prototype (MDTP) for RCT detection, based on machine learning (ML) and advanced numerical modeling of the system. We generate a generalizable dataset of scattering parameters through flexible numerical modeling in order to bypass real-world data collection challenges. This involves solving the linear system as a result of finite element discretization of the forward problem with use of the domain decomposition method to accelerate the computations. We use a support vector machine (SVM) to differentiate between injured and healthy shoulder models. This approach is more efficient in terms of required memory resources and computing time compared with traditional imaging methods.

Glenohumeral joint kinematics during apprehension-relocation test in patients with anterior shoulder instability and glenoid bone loss.

This study aimed to quantify the shoulder kinematics during an apprehension-relocation test in patients with anterior shoulder instability (ASI) and glenoid bone loss using the radiostereometric analysis (RSA) method. Kinematics were compared with the patient's contralateral healthy shoulder. A total of 20 patients with ASI and > 10% glenoid bone loss and a healthy contralateral shoulder were included. RSA imaging of the patient's shoulders was performed during a repeated apprehension-relocation test. Bone volume models were generated from CT scans, marked with anatomical coordinate systems, and aligned with the digitally reconstructed bone projections on the RSA images. The glenohumeral joint (GHJ) kinematics were evaluated in the anteroposterior and superoinferior direction of: the humeral head centre location relative to the glenoid centre; and the humeral head contact point location on the glenoid. During the apprehension test, the centre of the humeral head was 1.0 mm (95% CI 0.0 to 2.0) more inferior on the glenoid for the ASI shoulder compared with the healthy shoulder. Furthermore, the contact point of the ASI shoulder was 1.4 mm (95% CI 0.3 to 2.5) more anterior and 2.0 mm (95% CI 0.8 to 3.1) more inferior on the glenoid compared with the healthy shoulder. The contact point of the ASI shoulder was 1.2 mm (95% CI 0.2 to 2.6) more anterior during the apprehension test compared to the relocation test. The humeral head centre was located more inferior, and the GHJ contact point was located both more anterior and inferior during the apprehension test for the ASI shoulders than the healthy shoulders. Furthermore, the contact point displacement between the apprehension and relocation test revealed increased joint laxity for the ASI shoulder than the healthy shoulders. These results contribute to existing knowledge that ASI shoulders with glenoid bone loss may also suffer from inferior shoulder instability.

Subacromial balloon spacer improves isokinetic performance in patients with massive irreparable rotator cuff tear.

The aim of this study was to analyse clinical, functional and shoulder kinematics results using subacromial balloon spacer in nonreparable massive rotator cuff tears. Subacromial balloon spacer was hypothesised to improve shoulder kinematics and increases clinical and functional outcomes scores in nonreparable massive rotator cuff tears. This is a prospective study in massive rotator cuff tears. From October 2021 to October 2022, a total of 127 shoulders suffering massive rotator cuff tears were initially evaluated. All patients were evaluated preoperatively, at 6 and 12 months. Patients' patient-reported outcome measures (PROM) subjective values using visual analogue scale (VAS) and the Spanish Western Ontario Rotator Cuff Index (WORC) version were analysed. We also evaluated objective outcomes: constant score, range of movement and kinematic shoulder analysis (isokinetic test to evaluate internal and external rotation forces). Statistical analysis was conducted using SPSS software; continuous variables were presented as means and standard deviations (SDs). Seventeen nonrepairable massive rotator cuff tears were finally included. Three patients required reverse shoulder arthroplasty before 6 months postoperative. After 1-year follow-up, objective and subjective (PROM) outcome scores and isokinetic measurements improved in 13 patients. Preoperative VAS improved from 6.5 ± 2.1 to 2 ± 1.9 points on average at 1-year follow-up and WORC index from 1603 ± 217.3 to 699 ± 361.6. Constant score from 42.1 ± 13.1 on average and at 1-year follow-up increased to 60.8 ± 14.7. Range of movement also improved in elevation 122.2 ± 39.3 to 166.9 ± 25.8, abduction 120.3 ± 38.6 to 134.6 ± 21.1, external rotation 30.3 ± 19.7 to 86.1 ± 13.8 and internal rotation L4-T12 on average at 1-year follow-up. Isokinetic evaluation showed functional improvement 1 year after implantation. Both internal and external rotation improved compared with their healthy shoulder. External rotation improved from 30.3° ± 19.7° preoperatively to 86.1° ± 13.8° (43.7% in the isokinetic study) and internal rotation from L4 preoperatively to L1 (49.8% in isokinetic study) on average. Among the different alternatives for irreparable rotator cuff injuries surgical treatment, subacromial balloon spacer is an effective alternative in selected patients, both in terms of clinical-functional improvement and short-term isokinetic results. Level II.

Humeral rotation osteotomy is not associated with glenohumeral and scapulohumeral decentering at long-term follow-up

BackgroundWeber rotational osteotomy which increases humeral retrotorsion in patients with anterior shoulder instability has become unpopular because of recurrence of instability and high rates of early onset OA. However, the wear pattern in patients after rotational osteotomy remains unknown. The aim of this study was to determine the influence of surgically increased humerus retrotorsion on glenohumeral and scapulohumeral centering in a long-term follow-up. MethodsThe data of 18 shoulders in 18 patients diagnosed with a unilateral chronic recurrent anterior shoulder instability treated with an internal rotation subcapital humerus osteotomy between 1984 and 1990 were drawn from a previously published cohort and enrolled in the study. All patients had available bilateral CT scans performed after a mean follow-up of 14 (12-18) years. On these CT scans a comparison of the operated and the contralateral healthy side with regards to humerus torsion, glenoid version, glenoid offset, glenohumeral and scapulohumeral subluxation indices, rotator cuff action lines and osteoarthritic changes (OA) was performed. ResultsThe analysis of follow-up CT scans revealed a significantly higher mean humeral retrotorsion in the operated side compared to healthy side (41.6° ± 14.0° vs. 20.7°±8.2°, p<0.001). No differences were found in terms of glenohumeral subluxation index (0.50 ± 0.08 vs 0.51 ± 0.03, p = 0.259), scapulohumeral subluxation index (0.53 ± 0.09 vs 0.54 ± 0.03, p = 0.283), glenoid version (- 3.9° ± 4.6 vs - 4.1° ± 3.7, p = 0.424), glenoid offset (4.0 mm ± 2.8 vs 4.0 mm ± 1.3, p = 0.484), infraspinatus action lines (102.5° ± 4.7 vs 101.2° ± 2.1, p = 0.116) , subscapularis action lines (74.0° ± 6.0 vs 73.1° ± 2.3, p = 0.260) and resultant rotator cuff action lines (87.8° ± 4.9 vs 87.0° ± 1.8, p = 0.231) between operated and healthy shoulders. Osteoarthritic changes were observed in all operated shoulders and in 13 of 18 healthy shoulders. The OA Grade was mild in 5 patients, moderate in 11 and severe in 2 cases for operated shoulders and mild in 13 healthy shoulders at the last follow-up. ConclusionThe surgical increase of humeral retrotorsion by 20-30° did not affect glenohumeral and scapulohumeral centering in patients with a Weber rotational osteotomy after a long-term follow-up compared to the healthy side. While a high degree of early onset OA was observed it remains unclear whether the cause is the surgical interventions performed or the joint instability itself.

Finite element analysis part 1 of 2: Influence of short stem implant polyethylene configuration on glenohumeral joint biomechanics

AbstractPurposeStress shielding in short‐stem arthroplasty can cause critical metaphyseal bone loss. If the size and shape of the humeral shaft are important factors, it is unknown whether the shape of the polyethylene component in reverse shoulder arthroplasty (RSA) affects bone stress around or within the stem. We explored the impact of polyethylene shape on humeral and scapular stress distribution using a finite element model.MethodsWe developed a shoulder‐specific finite element model. A defined set of muscle forces was applied to simulate movements. An intact rotator cuff state and a superior deficient rotator cuff state were modelled. We used the FX V135 short stem in three conditions: total shoulder arthroplasty (TSA), and RSA with symmetrical and asymmetrical polyethylene (145°/135°). We measured biomechanical markers related to bone stress for different implant sizes. Joint kinematics and the mechanical behaviour of the implant were compared.ResultsRupture of the supraspinatus muscle produced a functionally limited shoulder. The placement of an anatomic TSA with an intact rotator cuff restored function similar to that of a healthy shoulder. RSA in the rotator cuff‐deficient shoulder restored function regardless of stem size and polyethylene shape. While stem size had an impact on the stress distribution in the bone and implant, it did not show significant potential for increasing or decreasing overall stress. For the same stem, stress distribution at the humerus is different between TSA and RSA. Polyethylene shape did not alter the transmission of stress to the bone in RSA. Asymmetric polyethylene produced a greater abduction range of motion.ConclusionsIn terms of bone stress distribution, smaller stems seemed more appropriate for TSA, while larger stems may be more appropriate for RSA. Polyethylene shape resulted in different ranges of motion but did not influence bone stress.Level of EvidenceDiagnostic Tests or Criteria; Level IV.

Inferior glenohumeral joint capsule thickness in frozen shoulder via ultrasonography

BackgroundThe thickening of the inferior glenohumeral joint capsule (IGC) is a characteristic finding in frozen shoulders. However, the relationship between the thickness of the IGC measured using ultrasonography (US) and the range of motion (ROM) remains unclear. This study aimed to investigate a suitable IGC thickness measurement site that can reflect the ROM of frozen shoulders. MethodsThe participants were Twenty-nine patients with frozen shoulder and 20 healthy shoulders of 10 healthy adult. US measurements of the IGC were performed at 80° elevation in the scapular plane, with thickness was measured at three levels in both groups: just above the surgical neck, just above the anatomical neck, and at the parenchymal level. The relationship between thickness and ROM at the three levels was also assessed. The thickness of the IGC was evaluated using MRI and US, as well as the validity of US evaluation. ResultsThere was a positive correlation (r=0.72) between MRI- and US-measured IGC thickness. The IGC was thicker in the frozen shoulder group than in the control group at all three levels (p<0.001). The thickness of the IGC at the parenchymal level showed a significant negative correlation with all ROMs: flexion (r = −0.63), abduction (r = −0.60), external rotation (r = −0.50), and internal rotation (r = −0.52). ConclusionThe thickness of the IGC at the parenchymal level is negatively correlated with the ROM. The evaluation of the IGC in this study will be helpful in selecting treatment options for frozen shoulders.

Establishing Normative Values for Acromion Anatomy: A Comprehensive MRI-Based Study in a Healthy Population of 996 Participants.

Shoulder pain is a common issue often linked to conditions such as subacromial impingement or rotator cuff lesions. The role of the acromion in these symptoms remains a subject of debate. This study aims to establish standardized values for commonly used acromion dimensions based on whole-body MRI scans of a large and healthy population and to investigate potential correlations between acromion shape and influencing factors such as sex, age, BMI, dominant hand, and shoulder pain. The study used whole-body MRI scans from the Study of Health in Pomerania, a German population-based study. Acromion index, acromion tilt, and acromion slope were measured. Interrater variability was tested with two independent, trained viewers on 100 MRI sequences before actual measurements started. Descriptive statistics and logistic regression were used to evaluate the results. We could define reference values based on a shoulder-healthy population for each acromion parameter within the 2.5 to 97.5 percentile. No significant differences were found in acromion slope, tilt, and index between male and female participants. No significant correlations were observed between acromion morphology and anthropometric parameters such as height, weight, or BMI. No significant differences were observed in acromion parameters between dominant and non-dominant hands or stated pain intensity. This study provides valuable reference values for acromion-related parameters, offering insight into the anatomy of a healthy shoulder. The findings indicate no significant differences in acromion morphology based on sex, weight, BMI, or dominant hand. Further research is necessary to ascertain the clinical implications of these reference values. The establishment of standardized reference values opens new possibilities for enhancing clinical decision making regarding surgical interventions, such as acromioplasty.

Sensory innervation of the human shoulder joints in healthy and in chronic pain shoulder syndromes

BackgroundAfferent innervation of shoulder joints plays a fundamental role in nociception and mechanoception and its alteration result in shoulder´s disease that course with pain and functional disability. MethodsJoints shoulder from healthy subjects (n = 20) and with chronic pain shoulder syndromes (n = 17) were analyzed using immunohistochemistry for S100 protein to identify nerve structures (nerve fibers and sensory corpuscles), coupled with a quantification of the sensory formations. Sensory nerve formations were quantified in 13 distinct areas in healthy joint shoulder and in the available equivalent areas in the pathological joints. Statistical analyses were conducted to assess differences between healthy shoulder and pathological shoulder joint (p< 0.05). ResultsAll analyzed structures, i.e., glenohumeral capsule, acromioclavicular capsule, the extraarticular structures (subcoracoid region and subacromio-subdeltoid bursa) and intraarticular structures (biceps brachii tendon and labrum articulare) are variably innervated except the extrinsic coracoacromial ligament, which was aneural. The afferent innervation of healthy human shoulder joints consists of free nerve endings, simple lamellar corpuscles and Ruffini’s corpuscles. Occasionally, Golgi-Mazzoni’s and Pacinian corpuscles were found. However, the relative density of each one varied among joints and/or the different zones within the same joint. As a rule, the upper half and anterior half of healthy glenohumeral capsules have a higher innervation compared to the lower and posterior respectably. On the other hand, in joints from subjects suffering chronic shoulder pain, a reduced innervation was found, involving more the corpuscles than free nerve endings. ConclusionsOur findings report a global innervation map of the human shoulder joints, especially the glenohumeral one, and this knowledge might be of interest for arthroscopic surgeons allowing to develop more selective and unhurt treatments, controlling the pain, and avoiding the loss of afferent innervation after surgical procedures. To the light of our results the postero-inferior glenohumeral capsular region seems to be the more adequate to be a surgical portal (surgical access area) to prevent nerve lesions.

FINITE ELEMENT ANALYSIS OF THE STRESS-STRAIN STATE OF 3D COMPUTER GENERATED IMAGING OF REVERSE TOTAL SHOULDER ENDOPROSTHESES

Objective. To conduct a finite element analysis of the stress-strain state (STS) of the elements of the shoulder joint after implantation reverse shoulder endoprostheses. Material and methods. After 3Dscanning of the composite model of the scapula and humerus, geometric models of the shoulder joint were built in the SolidWorks 2019 SP 1.0 program, followed by mathematical modeling and FEA. For the comparative analysis of the STS of the «bone – reverse endoprosthesis» s ystem, t hree-dimensional m odels o f two types of reverse shoulder endoprostheses were created, which were then transformed into a finite-element model and implanted into the developed three-dimensional mathematical model of the shoulder joint without cement. The STS calculations of the elements of endoprostheses were carried out for two positions: abduction 90° and flexion 90° with a load of 5 kg. Results. Compared to the healthy shoulder joint, models with reverse shoulder endoprosthesis have significantly different contact stresses and contact areas. It was established that the maximum stress in the details of the contact parts of the endoprosthesis when retracted at an angle of 90° did not exceed +1.78 MPa, when bending +5.8 MPa. The maximum stresses on the liner during shoulder abduction are +8.6 MPa, the minimum –7.38 MPa, during flexion +2.3 MPa and –2.45 MPa, respectively. It has been proven that the contact areas of the hemisphere and inserts of both reverse endoprostheses during abduction and flexion of the limb by 90° are significantly larger (573 mm2 vs. 1809–2081 mm2) when compared with a healthy shoulder joint, while changes in the area between the endoprostheses are insignificant and equal to 2...3 %. Conclusions. Analysis of the STS load of elements of reverse shoulder endoprosthesis showed that the greatest stresses occur in the contact zones. It has been proven that the maximum stresses on the contact structures of endoprostheses are less than on the head of a healthy joint, but the contact area during implantation of a reversible endoprosthesis of the shoulder joint increases significantly (more than 3 times).

Premorbid glenoid anatomy reconstruction from contralateral shoulder 3-dimensional measurements: a computed tomography scan analysis of 260 shoulders

Total shoulder arthroplasty (TSA) aims to reconstruct the premorbid anatomy of a pathologic shoulder. A healthy contralateral shoulder could be useful as a template in planning TSA. The symmetry between the left and right shoulders in healthy patients remains to be proved. The purpose of this study was to compare the 3-dimensional anatomy of the glenoid between sides in a healthy population. A multinational computed tomography scan database was retrospectively reviewed for all healthy bilateral shoulders in patients aged between 18 and 50 years. One hundred thirty pairs of healthy shoulder computed tomography scans were analyzed, and glenoid version, inclination, width, and height, as well as glenoid lateral offset and scapula lateral offset, were measured. All anatomic measures were computed with Blueprint, validated 3-dimensional planning software. The intraclass correlation coefficient was determined for each measure between left and right shoulders. The minimal detectable change (MDC) was calculated using the following formula: MDC=2×1.96×Standarderrorofmeasurement. The comparison between 130 pairs of healthy scapulae showed statistically significant differences in absolute values between right and left glenoid version (-5.3° vs. -4.6°, P<.01), inclination (8.4° vs. 9.3°, P<.01), and width (25.6 mm vs. 25.4 mm, P<.01), as well as scapula offset (105.8 mm vs. 106.2 mm, P<.01). Glenoid height was comparable between right and left shoulders (33.3 mm vs. 33.3 mm, P=.9). The differences between the means were always inferior to the MDC regarding glenoid version, inclination, height, and width, as well as scapula offset. Very strong intraclass correlation coefficients between the left and right shoulders were found for all evaluated paired measures. Healthy contralateral scapulae are highly reliable to predict inclination, height, width, and scapula offset and are reliable to predict version of a given scapula. Paired right and left scapulae were not statistically symmetrical regarding mean glenoid version, inclination, and width, as well as scapula offset. Nevertheless, the reported differences were not higher than the MDC for this cohort, confirming that healthy contralateral shoulders can be a useful template in TSA preoperative planning.

Three-dimensional finite element modeling of glenoid bone loss and baseplate fixation in reverse total shoulder arthroplasty

BackgroundPosterior glenoid bone loss is frequently observed in patients with osteoarthritis undergoing reverse total shoulder arthroplasty. Glenoid bone loss can reduce the baseplate back support area and the number of screws for fixation. The purpose of this study is to determine how initial baseplate fixation is affected by biomechanical factors introduced by glenoid bone loss such as reduced baseplate back support area and reduced screw number using three-dimensional finite element analysis. MethodsComputerized tomography images of a healthy shoulder were selected and segmented to obtain the solid geometry. Solid models were generated with 100%, 75%, 67%, 50%, and 25% glenoid baseplate back support. With these geometries, two groups of finite element models were then built. In the bone loss areas, screws were maintained in one group of models but were removed in the other group of models. 750N compressive loading was applied along the direction parallel to the scapula axis. Maximum von Mises stress and maximum micromotion between the bone and implant were recorded and evaluated for each glenoid bone model. ResultsIn the group of models where all screws remained in place, the maximum stress and maximum micromotion between the bone and implant exhibited minimal variation. The maximum stresses were 21.10MPa and the maximum micromotions were between 2-3 μm. However, in the group of models removing screws in the bone loss areas, maximum stress increased from 20MPa to 45MPa and maximum micromotion increased from 2 μm to 85 μm as the backside support area decreased from 100% to 25%. DiscussionIn conclusion, this three-dimensional finite element analysis study demonstrates that initial fixation can be achieved with approximately 1/3 posterior glenoid bone deficiency even without screw placement in the area of bone loss. Glenoid bone loss affects baseplate fixation mainly by reducing the screw numbers for fixation. If screws can be placed in the bone loss area, the decreased baseplate back support area will not result in increased stresses or micromotion leading to baseplate failure. This study suggests that surgeons should consider applying screws to the bone loss area if the remaining bone is able to hold the screw.

Load-induced increase in muscle activity during 30° abduction in patients with rotator cuff tears and control subjects

BackgroundRotator cuff muscles stabilise the glenohumeral joint and contribute to the initial abduction phase with other shoulder muscles. This study aimed to determine if the load-induced increase in shoulder muscle activity during a 30° abduction test is influenced by asymptomatic or symptomatic rotator cuff pathologies.Materials and MethodsTwenty-five patients with unilateral rotator cuff tears (age, 64.3 ± 10.2 years), 25 older control subjects (55.4 ± 8.2 years) and 25 younger control subjects (26.1 ± 2.3 years) participated in this study. Participants performed a bilateral 30° arm abduction and adduction movement in the scapular plane with handheld weights (0–4 kg). Activity of the deltoid, infraspinatus, biceps brachii, pectoralis major, latissimus dorsi and upper trapezius muscles was analysed at maximum abduction angle after normalisation to maximum voluntary contraction. Shoulders were classified into rotator cuff tendinopathy, asymptomatic and symptomatic rotator cuff tears, and healthy based on magnetic resonance images. A linear mixed model (loads, shoulder types) with random effects (shoulder identification) was applied to the log-transformed muscle activities.ResultsMuscle activity increased with increasing load in all muscles and shoulder types (P < 0.001), and 1-kg increments in additional weights were significant (P < 0.001). Significant effects of rotator cuff pathologies were found for all muscles analysed (P < 0.05). In all muscles, activity was at least 20% higher in symptomatic rotator cuff tears than in healthy shoulders (P < 0.001). Symptomatic rotator cuff tears showed 20–32% higher posterior deltoid (P < 0.05) and 19–25% higher pectoralis major (P < 0.01) activity when compared with asymptomatic tears.ConclusionsRotator cuff pathologies are associated with greater relative activity of shoulder muscles, even with low levels of additional load. Therefore, the inclusion of loaded shoulder tests in the diagnosis and rehabilitation of rotator cuff pathologies can provide important insight into the functional status of shoulders and can be used to guide treatment decisions.Level of evidence: Level 2.Trial registration: Ethical approval was obtained from the regional ethics committee (Ethics Committee Northwest Switzerland EKNZ 2021-00182), and the study was registered at clinicaltrials.gov on 29 March 2021 (trial registration number NCT04819724, https://clinicaltrials.gov/ct2/show/NCT04819724).

Analysis of the curative effect and prognostic factors in patients with scapular fracture with surgical indications after conservative treatment: a case series and clinical outcomes.

The choice of treatment for scapular fractures is a topic worth discussing. The type of scapular fracture is often complex, and more and more scholars prefer surgical treatment to obtain better shoulder joint function. In addition, because of the rich blood supply and muscles of the scapula, some scholars believe that simple suspension can also achieve satisfactory clinical effects. The aim of this study was to investigate the curative effect and prognostic factors of patients with scapular fracture with indications for surgery after receiving conservative treatment. Patients with scapular fracture who did not receive surgical treatment from July 2016 to May 2021 were recruited from the orthopedic trauma database of Nanjing Gulou Hospital, and the data from patients with indications for surgery were screened out for a retrospective analysis. The data were obtained from the database of orthopaedic trauma patients in Nanjing Drum Tower Hospital. The relevant data were recorded during telephone and video follow-up visits. Linear regression was used to analyze the factors associated with disabilities of the arm, shoulder and hand (DASH) score after receiving conservative treatment. A total of 21 patients were included in the final statistical analysis. All patients were followed up for 31.0±20.3 (range, 6-63) months, aged 52.9±12.7 (range, 27-71) years. All fractures had clinical healing with a 100% recovery satisfaction rate. Outcome measures of efficacy [both DASH scores and visual analogue scale (VAS) scores], were correlated with whether the fracture involved the superior border of the scapular, were not associated with the following variables: age (P=0.18), Injury Severity Score (ISS) score (P=0.10), the glenopolar angle (GPA) value (P=0.76), superior shoulder suspensory complex (SSSC) injury (P=0.82), and glenoid fracture (P=0.84). The range of motion of the affected shoulder was significantly reduced compared to the healthy shoulder (P<0.01), but the range of forward flexion and elevation was not significantly different from that of the healthy shoulder (P>0.05). Patients with fractures not involving the superior border of the scapula had a much lower range of motion in the affected shoulder than in the healthy shoulder during abduction (P<0.05). The range of surgical indications for scapular fractures with scapular fractures involving the lower margin of the scapular can be appropriately narrowed. Some patients with scapular fracture who have surgical indications can regain satisfactory shoulder function after receiving conservative treatment.

Concordance of shoulder strength assessments using a spring balance and isometric dynamometer in patients before and after arthroscopic rotator cuff repair

Shoulder strength is an essential assessment to monitor the outcome of treatment interventions. Isometric strength assessment in the Constant Score (CS) was initially measured with a cable tensiometer or spring balance (SB). Some authors have questioned the validity of this strength assessment and the resulting CS. The purpose of this study was to investigate the concordance of strength measurements using an unsecured SB vs. isometric dynamometer and outline the impact of these methods on the CS. In the context of routine clinical examination as well as participation in a Swiss national cohort study, shoulder strength was measured to calculate baseline (before surgery) and 6-month postoperative CS in adult rotator cuff tear patients who had undergone primary arthroscopic rotator cuff repair. Measurements of each of the operated and contralateral shoulders were made per patient routinely using an unsecured SB and study-specific using an isometric dynamometer in patients with the shoulder at 90° abduction in the scapular plane. Absolute and change values of strength and CS data were presented in scatter plots and assessed using concordance correlation coefficients (CCCs) and Bland-Altman plots. Between June 2020 and October 2021, baseline strength measurements from the operated shoulder of 78 patients ranged from 0.0 to 13.6 kg with a CCC of 0.64 (P<.001) and a mean difference of 0.81 kg between the SB and dynamometer methods. There were 89 measurements of the contralateral healthy shoulder that ranged from 3.6 to 15.6 kg; CCC and mean strength difference were 0.76 (P<.001) and 0.70 kg, respectively. At 6 months postsurgery, strength measurements of the operated shoulder ranged from 1.4 to 12.0 kg with a CCC of 0.66 (P<.001) and mean strength difference of 0.9 kg (n=68). Respective 6-month measurements of the contralateral side (n=52) ranged from 2.0 to 15.9 kg with a CCC of 0.73 (P<.001) and mean strength difference of 0.03 kg. Absolute and change values in shoulder strength assessments using an unsecured SB and isometric dynamometer are fairly concordant with mean differences of less than 1 kg between methods. With the variability of strength differences among patients, interpretation of these values for individual patients may be challenging. Nonetheless, unsecured SB and dynamometer methods share only slight and clinically unimportant differences that can provide similar group mean values for use in research along with the calculation of the CS.

Does COVID-19 vaccine exacerbate rotator cuff symptoms? A prospective study

BackgroundShoulder injury related to vaccine administration (SIRVA) is a rare but increasing complication after vaccination. The aim of this study was to increase awareness of post-vaccination shoulder pain and to investigate the effect of the clinical condition of the shoulder before vaccination on the loss of function that may occur after vaccination.MethodsThis prospective study included 65 patients aged > 18 years who were diagnosed with unilateral shoulder impingement and/or bursitis. The first vaccination was performed on the shoulders with rotator cuff symptoms, then the second vaccination was performed on healthy shoulders of same patients as soon as the health system allowed. Pre-vaccination MRI of the symptomatic shoulders of the patients was performed and VAS, ASES and Constant scores were evaluated. At 2 weeks after vaccination of the symptomatic shoulder, scores were reassessed. For the patients with changes in the scores, MRI was performed again and the treatment of all patients was started. A second vaccination was given to asymptomatic shoulders and the patients were recalled two weeks later and their scores were evaluated.ResultsAfter vaccination, the symptomatic shoulder of 14 patients was affected. No clinical changes were observed in the asymptomatic shoulders after vaccination. The VAS scores of the symptomatic shoulders evaluated after vaccination were significantly higher than the scores evaluated before vaccination (p = 0.001). The ASES and Constant scores of symptomatic shoulders evaluated after vaccination were significantly decreased compared to the scores evaluated before vaccination (p = 0.001).ConclusionsExacerbation of symptoms may occur if symptomatic shoulders are vaccinated. Before vaccination, a detailed anamnesis should be taken from the patients and vaccination should be performed to the asymptomatic side.

Poster 106: Association Between Glenoacromial Spacing and the Risk for Shoulder Instability

Objectives: Biomechanical studies have shown how the muscular dynamics about the shoulder are affected by the relative glenoid and acromion positions. Some believe these dynamics may play a role in predisposing shoulders to develop either osteoarthritis or rotator cuff disease. It is unclear if these dynamics also place individuals at increased risk for shoulder instability. To address these gaps in the literature, our objectives were to establish normative values for shoulder morphology in young physically active military service members and determine the influence of shoulder morphology, specifically the critical shoulder angle (CSA) and acromial index (AI) on rotator cuff strength and risk of shoulder instability. Methods: A subset of 160 US Service Academy cadets (25 Female, 18.81 ± 0.95 years, 177.01 ± 8.14 cm, and 72.52 ± 12.12 kg) were analyzed from a larger prospective cohort study, including all participants who sustained a shoulder instability injury during the 4-year follow-up period (n=36, all anterior). The remaining participants served as healthy controls. Upon entry to the primary study, baseline bilateral shoulder magnetic resonance imaging (MRI) and rotator cuff strength data were collected. Baseline MRIs were used to assess critical shoulder angle (CSA) defined as the angle formed between the glenoid plane at the inferior most glenoid to the lateral most aspect of the acromion and acromial index (AI) defined as glenoacromial distance (GA) divided by the glenohumeral distance (GH). Additionally, isometric internal rotation (IR) and external rotation (ER) strength was assessed at both 0° and 45° of glenohumeral abduction. Normative values for healthy shoulder morphology were reported by limb dominance. Multivariate linear regression models were used to estimate the association between shoulder morphology and strength. Finally, odds ratios (OR) were calculated using multivariate logistic regression models to estimate the likelihood of shoulder instability based on shoulder morphological outcomes. All multivariable models statistically controlled for the influence of potential confounding variables, including sex, height, weight, and limb dominance. Results: Normative baseline values for CSA, AI, glenohumeral distance and glenoacromial distance were established in young physically active military service members. In multivariate modeling, a positive relationship was detected between GH and ER strength at 45° abduction (Coefficient = 0.35, 95% CI: 0.04, 0.67), and between GA and IR strength at both 0° abduction (Coefficient = 4.29, 95% CI: 0.01, 8.56) and 45° abduction (Coefficient = 4.48, 95% CI: 0.81, 8.14). A positive relationship was detected between shoulder morphology and the likelihood of sustaining a shoulder instability injury (CSA: OR = 1.29, 95% CI: 0.97, 1.72; GA: OR = 14.63, 95% CI: 1.03, 206.98). These results indicate every 1° increase in CSA was associated with being 29% more likely to suffer a shoulder instability injury, while every 1cm increase in GA was associated with being 14 times more likely to suffer a shoulder instability injury. No other significant relationships were detected. Conclusions: Shoulder morphology was observed to play a role in both rotator cuff strength and the likelihood of glenohumeral instability injury. Interestingly, glenoacromial distance, specifically, was associated with both ER and IR strength, and the likelihood of shoulder instability. One theory is the larger the glenoacromial distance, the greater the moment arm for the anterior and posterior deltoid to act on the humerus. This increased mechanical advantage and resultant shear at the glenohumeral joint may be what contributes to the increased risk for instability. Another theory is the laterally placed acromion could be providing a fulcrum for the humerus to dislocate. Shoulder instability is a complex problem with many contributing factors and the glenoacromial scapular morphology may be yet another risk factor contributing to relative rotator cuff weakness and risk of shoulder instability in young active- duty military service members.

The effect of biceps tenotomy on superior humeral migration in arthroscopic repaired full-thickness supraspinatus tears

Lesions of the long head of the biceps (LHB) tendon are a prevalent injury that frequently coexists with rotator cuff injuries. This study aimed to assess the effect of supraspinatus (SST) repair with concurrent LHB tenotomy on superior migration of the humeral head. The acromiohumeral distance (AHD) was determined via ultrasound to evaluate the superior migration of the humeral head. The study population was retrospectively recruited from patients who underwent unilateral arthroscopic repair of isolated degenerative full-thickness SST tears between January 2017 and December 2019. Patients were divided into 2 subgroups based on whether they underwent LHB tenotomies during arthroscopy. While 37 patients underwent arthroscopic single-row SST repair, the other 33 patients underwent arthroscopic single-row SST repair with LHB tenotomy. The subject group consisted of people who had undergone arthroscopic shoulder surgery. Contralateral shoulders without rotator cuff injuries were included in the control group. The AHD and SST thicknesses of patients were examined via the ultrasound in both groups and subgroups. The mean age in the SST repair group was 55.52±4.58 years (range, 46-63 years), whereas it was 58.24±3.98 (range, 52-73 years) in the SST repair+LHB tenotomy group. In the SST repair group, 57.6% of patients were female and 42.4% were male, whereas 56.8% and 43.2% were in the SST repair+LHB tenotomy group, respectively. The mean body mass index was 28.06±1.31 kg/m2 (range, 25.7-31.2 kg/m2) in the SST repair group and 28.95±1.79 kg/m2 in the SST repair+LHB tenotomy group. Groups were not different for sex, surgery side, dominant side, tear size, and follow-up time; however, the SST repair+LHB tenotomy group had significantly higher mean age and body mass index than the SST repaired group. The mean AHD value and SST thickness were significantly less in both the rotator cuff repair group and the rotator cuff repair+LHB tenotomy group compared to the healthy shoulder. The mean AHD value was significantly lower in the SST repaired+LHB tenotomy group than in the SST repair group (P=.02). The AHD was narrowed in patients who underwent LHB tenotomy and radiologically demonstrated the depressor effect of the LHB tendon on the humeral head. As a secondary outcome, we demonstrated that regardless of tenotomy, AHD could not be restored in patients who underwent arthroscopic single-row SST repair.

Variation in Scapulohumeral Rhythm on Dynamic Radiography in Pathologic Shoulders: A Novel Diagnostic Tool.

Alterations in scapulohumeral joint kinematics occur in various shoulder pathologies. Conventional imaging provides a static assessment of soft tissue and morphologic changes. Quantifying the scapulohumeral rhythm (SHR), using Dynamic Digital Radiography (DDR) can offer clinicians a greater understanding of the pattern and extent of motion impairment as well as reliably monitor changes throughout the treatment course. The purpose of this study was to analyze the SHR of patients diagnosed with small (SRCT) and massive rotator cuff tears (MRCT), adhesive capsulitis (AC), and glenohumeral osteoarthritis (GH-OA) and compare their measurements to those of patient controls with healthy shoulders using DDR. The sequences of pulsed radiographs collated in DDR to create a moving image were prospectively analyzed during humeral abduction in normal controls and in 4 distinct shoulder pathology groups: SRCT, MRCT, AC, and GH-OA. GH and ST joint angles were measured at 0-30°, 30-60°, 60-90°, and maximal coronal plane humeral abduction. SHR was defined as the ratio of the change in humeral abduction over the change in scapula upward rotation during humeral abduction and was calculated within the above angle intervals. 121 shoulders were analyzed. 40 normal controls were compared to 13 SRCT, 29 MRCT, 16 AC, and 23 GH-OA. SHR during humeral abduction differed significantly in patients with MRCT (1.91 ± 0.72), AC (1.55 ± 0.37) and GH-OA (2.31 ± 1.01) compared to controls (3.39 ± 0.79). When analyzed across 30o intervals of abduction, there was a significantly lower SHR found at 0-30°, 30-60° and 60-90° in MRCT, AC, and GH-OA across each motion range compared to controls. Control patients had an arc of abduction of 103° ± 32° which was significantly larger than all other pathologies (MRCT: 76° ± 23°, SRCT: 81° ± 21°, AC: 65° ± 27°, GH-OA: 71° ± 35°) and an average scapular abduction of 33° ± 14°, which was significantly less than patients with a MRCT (46° ± 10°) and AC (65° ± 27°). SHR remained significantly lower throughout shoulder abduction in MRCT (43.65%), AC (-54.29%), and GH-OA (32.01%) compared to controls. When isolating for humeral and scapular motion, all 4 pathologies had decreased GH abduction, while AC and MRCT had an increased scapular compensatory motion compared to controls. Quantifying kinematic patterns like SHR using DDR can be implemented as a novel, safe, and cost-effective method to diagnose shoulder pathology and to monitor response to treatment.

Reliability of a Novel Preoperative Protocol for Determining Graft Sizes for Superior Capsular Reconstruction Using Plain Film Radiography.

Superior capsular reconstruction (SCR) for massive, irreparable rotator cuff tears involves anchoring a graft between the superior glenoid and the greater tuberosity of the humerus. Optimizing the graft size is important. We aimed (1) to evaluate the reliability of plain film radiography in determining graft size for SCR and (2) to create a database to help predict future graft sizes. An inter- and intra-rater reliability trial was conducted on 10 and 6 subjects with healthy shoulders, respectively, using plain film radiography to measure the distance between the superior glenoid and the supraspinatus footprint. The subjects were positioned upright with an abduction pillow modified to hold the shoulder at 30° abduction and 45° external rotation, afterwhich a true antero-posterior shoulder radiograph was captured. Thirty subjects were recruited for the database and grouped using the aforementioned protocol. The inter-rater and intra-rater trial agreement was excellent, with intraclass correlation coefficients of 0.94 (95% CI) and 0.76 (95% CI), respectively. Three medio-lateral patch sizes, of 33 mm, 38 mm, and 47 mm, were proposed based on the protocol in 30 subjects. Plain film radiography demonstrated excellent reliability in measuring the distance between the superior glenoid and the supraspinatus footprint. Three ordinal patch sizes are proposed.