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Background: Acquired acromial compromise, including thinning (less than 30% of the normal acromion) or fragmentation resulting from acromiohumeral impingement or previous acromioplasty, is a concern in reverse shoulder arthroplasty (RSA). This condition may lead to shoulder pain and difficulties in arm elevation because of acromial insufficiency fracture., Questions/purposes: (1) Do patients with acromial compromise (thinning less than 30% of normal acromion or fragmentation) have worse functional outcome scores, ROM, and strength after RSA compared with patients without acromial compromise? (2) Are patients with acromial compromise at a higher risk of complications such as acromial insufficiency fracture after RSA? (3) Do patients who develop acromial insufficiency fracture have predisposing associated factors and worse clinical outcomes?, Methods: Between January 1, 2016, and December 31, 2020, we treated 398 patients with RSA, and all patients were considered potentially eligible for this study. Our clinic is part of the orthopaedic department within a tertiary general hospital, serving patients from across the country. Among them, 49% (197 of 398) of patients were excluded for the following reasons: 8% (31 of 398) because of proximal humerus fracture, 5% (19 of 398) because of osteonecrosis, 9% (35 of 398) because of previous infective arthritis, 5% (18 of 398) because of a deformed shoulder, 4% (14 of 398) because of poor general condition after surgery, 3% (12 of 398) because of death, and another 17% (68 of 398) were lost before the minimum study follow-up, leaving 51% (201 of 398) for analysis. A preoperative acromial compromise was defined as follows: (1) thinning of the acromion (< 3 mm), which means a thickness of less than 30% of the normal acromion thickness (8 to 9 mm), and (2) acromial fragmentation. Acromial thickness was measured using a CT scan. The middle portion of the anterolateral acromion, situated lateral to the distal end of the clavicle, was crosschecked using the axial view. Measurements were subsequently performed from both coronal and sagittal views. In all, 29 patients with acromion compromise and 172 without acromion compromise met the inclusion and exclusion criteria. There was no differential loss to follow-up before 2 years between patients with and without acromial compromise in this study (36% [16 of 45] versus 23% [52 of 224]; p = 0.12). We matched patients using propensity score, pairing them in a 1:3 ratio based on gender, age, bone mineral density, diagnosis, previous rotator cuff repair surgery, subscapularis repair or latissimus dorsi transfer performed during surgery, the type of prosthesis used, and follow-up duration. Twenty-three patients with acromial compromise (acromion compromised group) and 69 patients without acromial compromise (normal control group) were matched; the mean ± SD duration of follow-up was 40 ± 22 months in those with acromial compromise and 43 ± 19 months the in normal control group. Pre- and postoperative functional outcome scores, ROM, and shoulder strength were compared. Shoulder scaption refers to lifting the arm in the scapular plane, and scaption strength was measured by applying upward force with the arm at 90° while seated, pushing it as far as possible and measured using a handheld myometer. Complications, including acromial insufficiency fracture, scapular notching, dislocation, periprosthetic infection, and overall risk of complication, were analyzed. Acromial insufficiency fracture was diagnosed based on clinical and radiological findings. Clinically, sudden pain and tenderness at the acromion along with reduced shoulder elevation raised acromial insufficiency fracture suspicion. Radiologically, acromion tilt on plain radiograph or fracture line on coronal CT view confirmed diagnosis of acromial insufficiency fracture., Results: Comparing both groups, patients with a compromised acromion had no difference in American Shoulder and Elbow Surgeons scores (60 ± 12 versus 64 ± 12; mean difference -4 [95% CI -11 to 2]; p = 0.16), Constant scores (48 ± 10 versus 54 ± 12; mean difference -6 [95% CI -13 to 0]; p = 0.06), forward flexion degree (125 ± 24 versus 130 ± 21; mean difference -5 [95% CI -16 to 6]; p = 0.36), and scaption strength (5 ± 3 versus 6 ± 3; mean difference -1 [95% CI -3 to 0]; p = 0.13). Having acromial compromise was not associated with increased risk of overall complications (30% [7 of 23] versus 19% [13 of 69], relative risk 2 [95% CI 1 to 4]; p = 0.26). However, the only complication that was higher in the acromial compromised group was infection (13% [3 of 23] versus 0% [0 of 69], relative risk not available; p = 0.01). Only the lateralized glenoid prosthesis demonstrated negative association with the acromial insufficiency fracture occurrence; no other factors showed an association. The use of lateralized glenoid prostheses was not observed in patients with acromial insufficiency fracture (0% [0 of 7] acromial insufficiency fracture versus 39% [33 of 85] no acromial insufficiency fracture, relative risk 0 [95% CI 0]; p = 0.047)., Conclusion: In patients with acquired acromial compromise-such as thinning or fragmented acromion because of advanced cuff tear arthropathy or previous acromioplasty-primary RSA resulted in no different functional outcome score, ROM, shoulder strength, and overall complications compared with patients without acromial compromise. Our findings suggest that a thin or fragmented acromion may not necessarily be exclusion criteria for RSA, potentially aiding surgeons in their decision-making process when treating these patients. However, one of the major complications, postoperative infection, is more frequently observed in patients with acquired acromial compromise. Pre- and postoperative caution would be necessary to prevent and detect infection even when short-term outcomes are favorable in this study. Further studies with large cohorts and long-term follow-up durations are needed., Level of Evidence: Level III, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 by the Association of Bone and Joint Surgeons.)

Purpose: To compare the critical shoulder angle (CSA), acromion index (AI), acromion angulation (AA) and glenoid version angle (GVA) between patients with full-thickness rotator cuff tears (RCTs) and patients with intact rotator cuffs., Methods: Between 2014 and 2018, the CSA, AI, AA and GVA were measured in consecutively included patients aged > 40 years who underwent shoulder arthroscopy for full-thickness RCTs. A total of 437 patients with RCTs and a mean age of 51.2 years (± 5.8) were included, 35.7% of whom were male. In the control group, there were n = 433 patients (36.3% male) with an intact rotator cuff, and the mean age was 50.7 years (± 5.3)., Results: The mean AI for the RCT group was 0.7 ± 0.1, which was significantly higher than the mean AI for the control group (0.6 ± 0.1, p < 0.001). The mean CSA for the RCT group was 33.6° ± 3.9°, which was significantly higher than the mean CSA for the control group (31.5° ± 4°, p < 0.001). The mean AA for the RCT group was 13.9° ± 9°, which was significantly higher than the mean AA for the control group (12.4 ± 8.6, p = 0.012). The mean GVA for the RCT group was - 3.5° ± 4.6° and significantly retroverted compared with the mean GVA for the control group (- 2.2° ± 4.6°, p < 0.001). The cutoff values determined by the ROC curve analyses were as follows: 0.6 for AI, 31.4° for CSA, 9.6° for AA and - 2.6° for GVA., Conclusion: The CSA, AI, GVA and AA values measured by MRI were determined to be significantly related to full-thickness rotator cuff ruptures. The AI, CSA, AA and GVA may be considered risk factors for degenerative rotator cuff tears. Assessing the CSA, AI, GVA and AA can be helpful for diagnostic evaluation of patients with full-thickness RCTs., Level of Evidence: III.

Purpose: To investigate whether arthroscopic lateral acromion resection can sufficiently reduce the critical shoulder angle (CSA) without damaging deltoid muscle insertion., Methods: Ninety patients who underwent arthroscopic rotator cuff (RC) repair were retrospectively analysed. According to the preoperative CSA, patients were categorized as Group I (CSA < 35°) and Group II (CSA ≥ 35°). Additional arthroscopic lateral acromion resection was performed in Group II. The CSA was measured 1 week postoperatively, while RC integrity and the deltoid attachment were assessed at 3, 6 and 12 months via ultrasound. Deltoid function was evaluated using the Akimbo test, in which patients place their hands on the iliac crest with abduction in the coronal plane and internal rotation of the shoulder joint while simultaneously flexing the elbow joint and pronating the forearm., Results: Large and massive RC tears were more prevalent in Group II (p = 0.017). In both groups, the CSA reduction was statistically significant (Group I = 1°: range 0°-3°, Group II = 3.7°: range 1°-8°; p < 0.001). When the preoperative CSA was > 40°, the respective postoperative CSA remained > 35° in 83.3% of cases (p < 0.001). Final shoulder strength was correlated with the amount of CSA reduction (rho = 0.41, p = 0.002). The postoperative CSA was higher, but not significantly different (n.s.), in patients with re-torn (36°, range 32°-40°) than with healed RC (33°, range 26°-38°). No clinical detachment or hypotrophy of the deltoid was observed with the Akimbo test and ultrasound evaluation., Conclusions: Arthroscopic lateral acromion resection is a safe procedure without affecting deltoid muscle origin or function, and it is effective in significantly reducing the CSA. However, the CSA cannot always be reduced to < 35°, especially in patients with preoperative CSA values > 40°., Level of Evidence: III.

Background: The purpose was to analyze the influence of deltoid lengthening due to different implant designs and anatomic variations of the acromion and scapular spine (SS) in the parasagittal plane on strain patterns after reverse shoulder arthroplasty (RSA)., Methods: Ten cadaveric shoulders with strain rosettes placed on the surface of the acromial body (Levy II) and SS (Levy III) were tested using a shoulder simulator. RSA using humeral onlay (+3, +5, +8, +10, +13 mm) and glenosphere lateralization (0, +6 mm) was performed. Arm lengthening and magnitude of strain on acromion/SS were measured. The length of deltoid was assessed using validated computer modeling. Anatomic variance of the SS angle and position of acromion in relation to the scapular plane was examined. For comparison of strain as a function of deltoid lengthening, 25 mm was used as a threshold value for comparison based on previous literature demonstrating a decrease in Constant score and active anterior elevation in patients with arm lengthening >25 mm., Results: At maximal deltoid lengthening (30.8 mm), average strains were 1112 με (acromion) and 1165 με (SS) (P < .01). There was an 82.6% increase in acromial strain at maximum lengthening compared with 25 mm (P = .02) and a strain increase of 79 με/mm deltoid lengthening above a threshold of 25 mm. The strain results delineated 2 anatomic groups: 5 of 10 specimens (group A) showed higher strain on SS (1445 με) vs. acromion (862 με, P = .02). Group A had a more posteriorly oriented acromion, whereas group B was anteriorly oriented (P < .001)., Conclusion: Deltoid lengthening above 25 mm produced large strains on the acromion/SS. Anatomic variation may indicate that as the acromion is more posteriorly oriented, the SS takes more strain from the deltoid vs. the acromion. Our study's data may help surgeons identify a high-risk population for increased strain patterns after RSA., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Most individuals with spinal cord injury who use manual wheelchairs experience shoulder pain related to wheelchair use, potentially in part from mechanical impingement of soft tissue structures within the subacromial space. There is evidence suggesting that scapula and humerus motion during certain wheelchair tasks occurs in directions that may reduce the subacromial space, but it hasn't been thoroughly characterized in this context., Methods: Shoulder motion was imaged and quantified during scapular plane elevation with/without handheld load, propulsion with/without added resistance, sideways lean, and weight-relief raise in ten manual wheelchair users with spinal cord injury using biplane fluoroscopy and computed tomography. For each position, minimum distance between rotator cuff tendon insertions (infraspinatus, subscapularis, supraspinatus) and the coracoacromial arch was determined. Tendon thickness was measured with ultrasound, and impingement risk scores were defined for each task based on frequency and amount of tendon compression., Findings: Periods of impingement were identified during scapular plane elevation and propulsion but not during pressure reliefs in most participants. There was a significant effect of activity on impingement risk scores (P < 0.0001), with greatest impingement risk during scapular plane elevation followed by propulsion. Impingement risk scores were not significantly different between scapular plane elevation loading conditions (P = 0.202) or propulsion resistances (P = 0.223). The infraspinatus and supraspinatus tendons were both susceptible to impingement during scapular plane elevation (by acromion), whereas the supraspinatus was most susceptible during propulsion (by acromion and coracoacromial ligament)., Interpretation: The occurrence of mechanical impingement during certain manual wheelchair tasks, even without increased load/resistance, demonstrates the importance of kinematics inherent to a task as a determinant of impingement. Frequency of and technique used to complete daily tasks should be carefully considered to reduce impingement risk, which may help preserve shoulder health long-term., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Minimal rotation of the scapula may affect the measurement of critical shoulder angle (CSA). We investigated the difference in the CSA measured in minimal rotation between the patients with rotator cuff tear and those without non-rotator cuff tear and the CSA measurement error by comparing with computed tomography (CT)., Methods: We retrospectively reviewed patients with full-thickness rotator cuff tear and whose X-ray views correspond to Suter-Henninger classification type A1 and C1. The CSA values between the normal control group (without rotator cuff tear) and the rotator cuff tear group were compared according to A1 type and C1 type. In the rotator cuff tear group, we compared the CSA values measured by using X-ray and CT., Results: A total of 238 patients (rotator cuff tear group, 139 patients; normal cuff group, 99 patients) were included in this study. The mean CSA of the rotator cuff tear group was 33.4° ± 3.5°, and that of the normal cuff group was 32.6° ± 3.9° ( p = 0.085). On comparison of the CSA according to the Suter-Henninger classification type, the CSA values on the A1 type view and C1 type view were 32.7° ± 3.5° and 33.7° ± 3.5°, respectively, in the rotator cuff tear group and 30.5° ± 3.1° and 33.1 ± 3.9°, respectively, in the normal cuff group ( p = 0.024 and p = 0.216, respectively). The mean CSA was 32.5° ± 3.1° in CT and 33.3° ± 3.2° in X-ray ( p = 0.184). On comparison of the CSA according to the Suter-Henninger classification type, the CSA values on the A1 type view and C1 type view were 32.6° ± 3.6° and 32.5° ± 2.4°, respectively, in CT and 32.5° ± 3.5° and 34.2° ± 2.6°, respectively, in X-ray ( p = 0.905 and p = 0.017, respectively)., Conclusions: The X-ray view corresponding to Suter-Henninger classification type A1 or CT-reconstructed image can be used to reduce the measurement error and obtain reliable CSA values. The CSA measured on the X-ray view corresponding to Suter-Henninger classification type A1 may be related with rotator cuff tear., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported.

Background: The purpose of this paper was to determine whether acromial morphology influences anteroposterior shoulder stability. We hypothesized that a more horizontal and higher position of the acromion in the sagittal plane would be associated with posterior instability., Methods: In this retrospective study, patients with unidirectional posterior instability were age and sex-matched to a cohort of patients with unidirectional anterior instability. Both cohorts were compared with a control group of patients with no instability and no degenerative glenohumeral (rotator cuff and/or joint surface) or acromial changes. Measurements on radiographs included posterior acromial tilt, anterior and posterior acromial coverage (AAC and PAC), posterior acromial height (PAH), and the critical shoulder angle (CSA)., Results: The number of patients enrolled in each instability group was 41, based on a priori power analysis. The control group consisted of 53 shoulders. Of the measured anatomic factors, PAH showed the most significant association with posterior instability (odds ratio [OR] = 1.8; p < 0.001) in the logistic regression model. PAH was significantly greater in the posterior instability group compared with the anterior instability group (30.9 versus 19.5 mm; p < 0.001). With a cutoff value of PAH of 23 mm, the OR for posterior instability was 39. Shoulders with posterior instability were also significantly different from normal shoulders with regard to PAH (p < 0.001), AAC (p < 0.001), and PAC (p < 0.001) whereas, in the shoulders with anterior instability, all of these values except the AAC (p = 0.011) did not differ from those of normal shoulders., Conclusions: Specific acromial morphology is significantly associated with the direction of glenohumeral instability. In shoulders with posterior instability, the acromion is situated higher and is oriented more horizontally in the sagittal plane than in normal shoulders and those with anterior instability; this acromial position may provide less osseous restraint against posterior humeral head translation. A steep "Swiss chalet roof-type" acromion virtually excluded recurrent posterior instability in an albeit relatively small cohort of patients. Additional investigation is needed to determine the relevance of these findings for future treatment., Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Objectives: Prolotherapy is an injection-based complementary treatment for various musculoskeletal diseases. The aim of this study was to evaluate the therapeutic efficacy of ultrasound-guided prolotherapy in the treatment of acromial enthesopathy and acromioclavicular joint arthropathy., Methods: Thirty-one patients with chronic moderate-to-severe shoulder pain were recruited from September 2015 to September 2017. Ultrasound-guided prolotherapy was performed by injecting 10 mL of a 15% dextrose solution into the acromial enthesis of the deltoid or acromioclavicular joint capsule aseptically. Prolotherapy was given in 2 sessions separated by a 1-month interval. The pretreatment-to-posttreatment change in the pain visual analog scale (VAS) score was recorded as the primary outcome. The mean follow-up duration was 61.8 days. A paired t test was used to assess the difference in pretreatment and posttreatment VAS scores. A univariate logistic regression analysis was conducted to identify the demographic variables associated with substantial pain reduction after the intervention. Substantial pain reduction was defined as a posttreatment VAS score of 3 or less., Results: Twenty of the 31 patients reported substantial pain reduction without adverse effects after the intervention. The mean VAS score reduction ± SD was 4.3 ± 2.6 (pretreatment, 6.8 ± 1.5; posttreatment, 2.5 ± 2.1; P < .01)., Conclusions: Ultrasound-guided prolotherapy with a 15% dextrose solution is an effective and safe therapeutic option for moderate-to-severe acromial enthesopathy and acromioclavicular joint arthropathy., (© 2018 by the American Institute of Ultrasound in Medicine.)

Management of a persistently symptomatic, unstable os acromiale remains controversial. An unstable os acromiale is an easy diagnosis to miss and should be specifically evaluated for in patients with shoulder pain and a high degree of clinical suspicion. Surgical options include open or arthroscopic excision and open reduction and internal fixation. Open excision of large fragments has had poor results. Arthroscopic treatment is commonly used for small fragments (preacromion), and the technique has also been used in larger fragments (meso-os), but concerns persist over postoperative weakness secondary to shortening of the deltoid lever arm. Open reduction and internal fixation through a transacromial approach has been shown to have predictable union rates but can be complicated by symptomatic implant. Recent biomechanical studies have expanded our understanding of optimal fixation constructs, which may also decrease implant-related issues. Ultimately, the choice of which procedure to use will be dictated by patient factors such as age, activity level, and the nature of rotator cuff pathology. LEVEL OF EVIDENCE:: Level V.

Background: Residual shoulder dysfunction and deformity impacts on functional performance in children with obstetric brachial plexus palsy. Clinical understanding of upper limb dynamic movement patterns is difficult with observation alone. This case-control study describes the significant kinematic differences between children with obstetric brachial plexus palsy compared to typically developing children while performing tasks of the modified Mallet Scale., Methods: Eleven children with obstetric brachial plexus palsy (mean 10 years, range 7-15 years, Narakas group I-III) and 10 typically developing children (mean 9 years 9 months, range 6-15 years) completed three-dimensional upper limb motion analysis using the acromion method to track dynamic scapular movement. Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics., Findings: Joint rotation angles against time of the glenohumeral, thoracohumeral and scapulohumeral joints were calculated. Kinematic findings demonstrated increased internal rotation in all postures, reduced glenohumeral excursion, habitual "trumpet" posture of glenohumeral abduction/elevation and variability in movement strategies. Scapulohumeral rhythm during abduction task was 1.88:1 in typically developing children and 1.04:1 in children with obstetric brachial plexus palsy., Interpretation: Children with obstetric brachial plexus palsy demonstrate deficient external rotation in all tasks. Despite increased postural internal rotation, ability to move through internal rotation range is compromised. The glenohumeral joint showed the greatest range deficit, contributing to abnormal scapulohumeral rhythm. Future sub-group analysis of Narakas Classification is recommended., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Shoulder pain is a common clinical problem affecting most individuals in their lifetime. Despite the high prevalence of rotator cuff pathology in these individuals, the pathogenesis of rotator cuff disease remains unclear. Position and motion related mechanisms of rotator cuff disease are often proposed, but poorly understood. The purpose of this study was to determine the impact of systematically altering glenohumeral plane on subacromial proximities across arm elevation as measures of tendon compression risk. Three-dimensional models of the humerus, scapula, coracoacromial ligament, and supraspinatus were reconstructed from MRIs in 20 subjects. Glenohumeral elevation was imposed on the humeral and supraspinatus tendon models for three glenohumeral planes, which were chosen to represent flexion, scapular plane abduction, and abduction based on average values from a previous study of asymptomatic individuals. Subacromial proximity was quantified as the minimum distance between the supraspinatus tendon and coracoacromial arch (acromion and coracoacromial ligament), the surface area of the supraspinatus tendon within 2 mm proximity to the coracoacromial arch, and the volume of intersection between the supraspinatus tendon and coracoacromial arch. The lowest modeled subacromial supraspinatus compression measures occurred during flexion at lower angles of elevation. This finding was consistent across all three measures of subacromial proximity. Knowledge of this range of reduced risk may be useful to inform future studies related to patient education and ergonomic design to prevent the development of shoulder pain and dysfunction., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

An irreparable cuff tear is defined as the inability to achieve direct repair of native tendon to the great tuberosity despite intra- and extra-articular release of the remaining tissue. Three distinct anatomic patterns are identified: posterosuperior cuff tears which involve the supraspinatus, infraspinatus and teres minor; anterosuperior tears which involve the supraspinatus and subscapularis; and global tears which comprise both. Subacromial debridement and tenotomy or tenodesis of the long head of the biceps are proposed for older patients with a functional but very painful shoulder. Partial repair-particularly the infraspinatus and the subscapularis-is indicated for young patients if the muscle is still trophic with a fatty infiltration less than 3. It can be combined with a tendon transfer. In irreparable posterosuperior tears, latissimus dorsi or lower trapezius transfer has been reported to improve active elevation and external rotation. In anterosuperior cuff tears, pectoralis major or latissimus transfer has been used. If the lack of external rotation is isolated with good active forward elevation, the L'Episcopo procedure is the procedure of choice. New techniques with a short follow-up have been proposed recently: implantation of a balloon-shaped, biodegradable spacer in the subacromial space to maintain the position of the humeral head and to facilitate deltoid action; capsular superior reconstruction with a fascia lata or an artificial graft implanted between the superior glenoid rim and the great tuberosity to reproduce the natural capsule of the supra- and infraspinatus and to stabilize the humeral head.

Objective: The aim of this study was to evaluate the effectiveness of the extracorporeal shock wave therapy in the subacromial impingement syndrome and its relationship with the acromion morphology., Methods: Thirty patients (24 women, 6 men) with subacromial impingement were evaluated. The average age of patients was 53.6 ± 9.8 years (range 39-80). Patients were divided into 3 groups according to the acromion morphology. ESWT 1500 at 0.12 am mL/mm 2 violence was applied once a week for 3 weeks. Shoulder pain and disability index (SPADI) was used to assess function and pain scores of the patients. The evaluations were made prior to and 12 weeks after the ESWT., Results: Thirteen shoulders had type 1 acromion, 11 shoulders type 2 acromion and 6 shoulders type 3 acromion. After ESWT, the SPADI pain score decreased from 16.1 ± 5.1 (7-25) to 10.4 ± 4.9 (1-20); SPADI functional score decreased from 37.3 ± 19.8 (5-70) to 26.7 ± 17.5 (1-60); SPADI total score decreased from 53.4 ± 24.5 (14-95) to 37.1 ± 21.6 (2-74) (p < 0.05; paired t test). In each group better functional outcomes were achieved after ESWT (p < 0.05; paired t test). There were no differences between the groups according to functional outcome both before and after the ESWT treatment (p > 0.05, one way ANOVA test)., Conclusion: ESWT was found to be effective in the treatment of impingement syndrome both for pain and functional outcome in the early period regardless of acromion morphology., Level of Evidence: Level IV, Therapeutic study., (Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.)

Purpose: A clavicle hook plate is a simple and effective method for treating acromioclavicular dislocation and distal clavicle fractures. However, subacromial osteolysis and peri-implant fractures are complicated for surgeons to manage. This study uses finite element analysis (FEA) to investigate the post-implantation biomechanics of clavicle hook plates with different hook angles., Methods: This FEA study constructed a model with a clavicle, acromion, clavicle hook plate, and screws to simulate the implantation of clavicle hook plates at different hook angles (90°, 95°, 100°, 105°, and 110°) for treating acromioclavicular joint dislocations. This study investigated the biomechanics of the acromion, clavicle, hook plate, and screws., Results: A smaller hook angle increases the stress on the middle third of the clavicle. A larger hook angle increases the force exerted by the clavicle hook plate on the acromion. The screw at the most medial position on the plate generated the highest stress. The highest stress on the implanted clavicle hook plate was on the turning corner of the hook., Conclusions: A clavicle hook plate with different hook angles may induce different biomechanical behaviors in the clavicle and acromion. Orthopedic surgeons must select a suitable clavicle hook plate based on the anatomical structure of each patient.

Background/hypothesis: The relation between acromiohumeral distance (AHD) and severity of pain, disability and range of movement (ROM) in patients with chronic rotator cuff related shoulder pain (RCRSP) has not been reported., Objectives: The aim of this study was to investigate the level of association between AHD measured by ultrasonography and pain-disability and shoulder range of movement (ROM), in patients suffering from chronic RCRSP. As a secondary objective, the determination of the intrarater reliability of AHD at both 0 and 60 degrees of shoulder elevation was carried out., Design: This was a cross-sectional study., Method: A sample comprised of 97 patients with chronic RCSRP symptoms was recruited from three different primary care centres. Acromio-humeral distance (AHD) measured by ultrasonography at 0 and 60 degrees of shoulder elevation, shoulder pain-function (SPADI) and range of movement (ROM) were taken., Results: There was no correlation between AHD at 0° (-0,215), and at 60° (-0,148), with SPADI. No correlations were found with AHD and shoulder ROM at both 0 and 60°. Intrarater reliability was excellent for AHD at 0 and 60°., Conclusions: There was a small association between AHD and shoulder pain and function, as well as with shoulder ROM, in patients with chronic RCRSP. Hence, clinicians should consider other possibilities rather than focusing their therapies only in increasing AHD when patients with chronic RCRSP are treated., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: US-examinations related to shoulder impingement (SI) often vary due to methodological differences, examiner positions, transducers, and recording parameters. Reliable US protocols for examination of different structures related to shoulder impingement are therefore needed., Objectives: To investigate the intra- and inter-rater reliability of the existing ultrasound (US) examinations of the subacromial space, the subacromial-subdeltoid bursa, and the supraspinatus tendon., Method: In a three-phased design, two physiotherapists using a standardized US protocol examined the thickness of the supraspinatus tendon (SUPRA) and subacromial subdeltoid (SASD) bursa in two imaging positions, and the acromial humeral distance (AHD) in one position. Additionally, agreement on dynamic impingement (DI) examination was performed. The intra- and inter-rater reliability was carried out on the same day., Participants: Forty-six sports active participants with a mean age of 37 years (range 18-57) participated. Twenty-two had SI and pain within previous week and 24 did not have SI or pain within previous week., Results: Intra- and inter-rater reliability ICC (2,3) models were all above 0.80 (range 0.82-0.99) with no systematic bias (Bland Altman plots). For the DI examination, the overall agreement was 98% and 93%, with Kappa of 0.96 and 0.82, for intra- and inter-rater reliability, respectively., Conclusion: The reliability of the current standardized protocol for US examination of SI was excellent and considered feasible for clinical practice.

Background: The full can test is theorized to produce compressive loads on the supraspinatus tendon within the subacromial space. Characterizing the width of the subacromial outlet, scapular orientation, and shoulder pain during the full can test will improve the mechanistic understanding of the positive full can test., Methods: Cross-sectional repeated measures design. Participants with subacromial pain syndrome (n=30) were compared to a matched control group (n=30) during 2 conditions: passive support, and the full can test. The full can test was performed with the arm elevated to 90° in the scapular plane. In both conditions, measurements were taken of acromiohumeral distance with ultrasonography, scapular position using electromagnetic tracking, shoulder strength using a dynamometer, and shoulder pain with the 11-point rating scale., Findings: During the full can test, both groups had a decreased acromial humeral distance, scapular upward rotation, posterior tilt, external rotation and clavicular protraction as compared to passive support (p<0.05). The subacromial pain group as compared to the control group reported greater shoulder pain (p<0.001), reduced strength (p=0.002) and greater scapular anterior tilt (p<0.05) during the full can test., Interpretation: This study indicates the mechanisms of a full can test are a reduction in the acromial humeral distance, accompanied by scapular kinematic changes. A positive test of increased pain and reduced strength in those with subacromial pain syndrome can be explained additionally by an increase in scapular anterior tilt. These mechanistic changes may lead to tendon compression, but this cannot be verified as direct tendon compression was not measured., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We present the clinical case of a 14-year-old female patient complaining of omalgia. A focus of osteoid osteoma located in the acromion was diagnosed. The lesion was removed using the arthroscopic technique, and the symptoms subsided completely. We also present a review of published papers regarding unusual locations of osteoid osteoma.

Background: Although functional results of combined rehabilitation programs are reported, there have been no reports studying the effects of solo pendulum exercises on ultrasonographic measurements of acromiohumeral distance (AHD)., Objective: To investigate the effects of weighted and un-weighted pendulum exercises on ultrasonographic AHD and clinical symptoms in patients with subacromial impingement syndrome., Methods: Patients with subacromial impingement syndrome were randomized to performing weighted (1.5 kilograms hand held dumbbell, N= 18) or un-weighted (free of weight, N= 16) pendulum exercises for 4 weeks, 3 sessions/day. Exercises were repeated for each direction of shoulder motion in each session (ten minutes). Clinical situation was evaluated by Constant score and Shoulder Pain Disability Index (SPADI). Ultrasonographic measurements of AHD at 0°, 30° and 60° shoulder abduction were performed. All clinical and ultrasonographic evaluations were performed at the beginning of the exercise program and at end of 4 weeks of exercise program., Results: Thirty-four patients (23 females, 11 males; mean age 41.7 ± 8.9 years) were evaluated. Significant clinical improvements were detected in both exercise groups between pre and post-treatment evaluations (p < 0.05). There was no significant difference for pre and post-treatment AHD measurements at 0°, 30°, and 60° shoulder abduction between groups (p > 0.05). There was no significant difference for pre and post-treatment narrowing of AHD (narrowing of 0°-30°, and 0°-60°) between groups (p > 0.05)., Conclusion: While significant clinical improvements were achieved with both weighted and un-weighted solo pendulum exercises, no significant difference was detected for ultrasonographic AHD measurements between exercise groups.

Background: Topographical pain maps (TPM) are useful tools to assess deep tissue sensitivity in musculoskeletal pain conditions. There is evidence suggesting bilateral sensitivity in subacromial pain syndrome (SAPS), although it is not widely accepted. No previous study has investigated TPM of the shoulder in SAPS., Objective: To investigate whether differences for TPM of the shoulder are evident among patients with unilateral SAPS and controls., Methods: Pressure pain thresholds (PPTs) were assessed 3 times at each point and there was a 20 s rest period between each one. The TPM were calculated using 29 pre-determined points on both shoulders in all groups by inverse distance weighted interpolation of PPT data. Multivariate Analysis of Covariance was applied to detect differences in PPTs between groups, sides, points (gender as covariate)., Results: The results revealed significant differences between points and genders (both, P < 0.001), but not between groups (P = 0.243) and sides (P = 0.812). Heterogeneous distribution of mechanical pain sensitivity was found in both groups as the PPTs were lower on the root spine of the scapula and the posterior border of the acromion (points 5-8, P < 0.05), glenohumeral joint (points 17-20, P < 0.01) and the anterior deltoid muscle (points 21-25, P < 0.001) compared to the average of the other sites on the shoulder. Women exhibited bilateral lower PPTs in all points than men in both groups (all, P < 0.01)., Conclusions: This study revealed no differences for mechanical pain sensitivity in patients with SAPS experiencing lower levels of pain compared with matched controls, but showed heterogeneous distribution of PPTs in the shoulder., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Unlabelled: Displaced fractures of the acromion are rare injuries. A 45-year-old lady presented with an isolated acromion fracture (type III, Kuhn classification) resulting from a direct blow to the top of her right shoulder in a fall while skiing. After standard clinical and radiological examination of the shoulder, an open reduction and internal plate fixation using a postero-superior approach to the scapula was performed. Early rehabilitation of the arm and shoulder was initiated. At 50 days after surgery the patient achieved a full range of motion in her right shoulder and muscle strength equal to that of the contralateral extremity. By 12 weeks radiographic union of the fracture was recorded. The final functional outcome after open reduction and internal plate fixation of the fracture was comparable with results reported in the literature and, in comparison with conservative treatment, the risk of non-union was significantly reduced., Key Words: acromion fracture, scapula, osteosynthesis.

Background: Arthroscopic subacromial decompression (ASAD) is a commonly performed surgical intervention for shoulder pain. The rationale is that removal of a bony acromial spur relieves symptoms by decompressing rotator cuff tendons passing through the subacromial space. However, the efficacy of this procedure is uncertain. The objective of this trial was to compare the efficacy and cost-effectiveness of ASAD in patients with subacromial pain using appropriate control groups, including placebo intervention., Methods/design: The trial is a three-group, parallel design, pragmatic, randomised controlled study. The intervention content for each group (ASAD, active monitoring with specialist reassessment (AMSR) and investigational shoulder arthroscopy only (AO)) enables assessment of (1) the efficacy of the surgery against no surgery; (2) the need for a specific component of the surgery-namely, removal of the bony spur; and (3) quantification of the placebo effect. Concealed allocation was performed using a 1:1:1 randomisation ratio and using age, sex, baseline Oxford Shoulder Score (OSS) and centre as minimisation criteria. The primary outcome measure is the OSS at 6 months post randomisation. A total of 300 patients recruited over 24 months from a minimum of 14 UK shoulder units over 24 months were required to detect a difference of 4.5 points on the OSS (standard deviation, 9) with 90% power and to allow for 15% loss to follow-up. Secondary outcomes include cost-effectiveness, pain, complications and patient satisfaction. A substantial qualitative research component is included. The primary analysis will be conducted on the modified intention-to-treat analysis. Sensitivity analysis will be used to assess the robustness of the results with regard to the underlying assumptions about missing data using multiple imputation., Discussion: This trial uses an innovative design to account for the known placebo effects of surgery, but it also will delineate the mechanism for any benefit from surgery. The investigational AO group is considered a placebo intervention (not sham surgery), as it includes all components of subacromial decompression except the critical surgical element. Some discussion is also dedicated to the challenges of conducting placebo surgery trials., Trial Registrations: UK Clinical Research Network UKCRN12104. Registered 22 May 2012. International Standard Randomised Controlled Trial ISRCTN33864128 . Registered 22 June 2012. ClinicalTrials.gov NCT01623011 . Registered 15 June 2012.

Shoulder injuries may be associated with proprioceptive deficits, however, it is unknown whether these changes are due to the experience of pain, tissue damage, or a combination of these. The aim of this study was to investigate the effect of experimentally-induced sub-acromial pain on proprioceptive variables. Sub-acromial pain was induced via hypertonic saline injection in 20 healthy participants. Passive joint replication (PJR) and threshold to detection of movement direction (TTDMD) were assessed with a Biodex System 3 Pro isokinetic dynamometer for baseline control, experimental pain and recovery control conditions with a starting position of 60° shoulder abduction. The target angle for PJR was 60° external rotation, starting from 40°. TTDMD was tested from a position of 20° external rotation. Repeated measures ANOVAs were used to determine differences between PJR absolute and variable errors and TTDMD for the control and experimental conditions. Pain was elicited with a median 7 on the Numeric Pain Rating Scale. TTDMD was significantly decreased for the experimental pain condition compared to baseline and recovery conditions (≈30%, P = 0.003). No significant differences were found for absolute (P = 0.152) and variable (P = 0.514) error for PJR. Movement sense was enhanced for the experimental sub-acromial pain condition, which may reflect protective effects of the central nervous system in response to the pain. Where decreased passive proprioception is observed in shoulders with injuries, these may be due to a combination of peripheral tissue injury and neural adaptations that differ from those due to acute pain., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Purpose: The aim of the present study was to investigate whether coracoacromial arch angle is a predisposing factor for rotator cuff tears., Methods: Shoulder magnetic resonance imaging (MRI) examinations of 40 patients having shoulder arthroscopy due to rotator cuff tears and 28 patients with normal MRI findings were evaluated retrospectively. Acromio-humeral distance, coraco-humeral distance, the angle between the longitudinal axis of the coracoacromial ligament and longitudinal axis of the acromion (coracoacromial arch angle), and thickness of the coracoacromial ligament were measured., Results: In patients with rotator cuff pathology the mean coraco-humeral distance was 7.88±2.37 mm, the mean acromio-humeral distance was 7.89±2.09 mm, and the mean coracoacromial arch angle was 132.38°±6.52° compared to 11.67±1.86 mm, 11.15±1.84 mm, and 116.95°±7.66° in the control group, respectively (P < 0.001, for all). In regression analysis, all three parameters were found to be significant predictors of rotator cuff tears. The mean thickness of the coracoacromial ligament was not significantly different between the patient and control groups (0.95±0.30 mm vs. 1.00±0.33 mm, P > 0.05)., Conclusion: Acromio-humeral and coraco-humeral distances are narrower than normal limits in patients with rotator cuff tears. In addition, coracoacromial arch angle may be a predisposing factor for rotator cuff tears.

Background: Superior migration of the humeral head after massive rotator cuff tear (mRCT) is thought to lead to cuff tear arthropathy. Previous biomechanical studies have demonstrated the ability of the pectoralis major and latissimus dorsi (PM/LD) muscles to resist this migration. This study examined the role of PM/LD muscles on glenohumeral joint forces and acromiohumeral contact pressures in a mRCT model., Methods: Six cadaveric shoulders were tested using a custom shoulder-testing system. Muscle insertions of the rotator cuff, deltoid, and PM/LD were preserved and used for muscle loading. Specimens were tested in 3 different humeral rotation positions at 0° abduction and 2 rotation positions at 60° abduction. Testing was performed for intact specimens, after supraspinatus removal, and after supraspinatus/infraspinatus/teres minor removal. PM/LD were loaded or unloaded to determine their effect. Humeral head kinematics, glenohumeral joint forces, and acromiohumeral contact area and pressure were measured., Results: For the mRCT condition at 0° abduction, unloading the PM/LD resulted in superior shift of the humeral head. Acromiohumeral contact pressures were undetectable when the PM/LD were loaded but increased significantly after PM/LD unloading. After mRCT, superior joint forces were increased and compressive forces were decreased compared with intact; loading the PM/LD resolved these abnormal forces in some testing conditions., Conclusion: In mRCT, the PM and LD muscles are effective in improving glenohumeral kinematics and reducing acromiohumeral pressures. Strengthening or neuromuscular training of this musculature, or both, may delay the progression to cuff tear arthropathy., (Published by Mosby, Inc.)

Ultrasonographic measurements of acromion-greater tuberosity (AGT) distance have shown to be reliable and valid in the assessment of glenohumeral subluxation (GHS) in patients with stroke. The primary aim of this study was to investigate the effect of arm positions on ultrasonographic measurements of AGT distance. The secondary aim was to assess the intra-rater reliability of AGT distance in different arm positions. Sixteen healthy individuals with a mean age 28 standard deviation 11 years who gave informed written consent were recruited. Four clinically relevant arm positions for patients with stroke were selected: (1) arm hanging freely by the side; (2) forearm on a pillow placed on participants lap with the elbows at 90° flexion and the forearms in pronation; (3) as in position 2, but with the elbow supported and (4) shoulder in 10° of abduction and 60° of flexion with the arm resting on a pillow placed on a table. Repeated measures analysis of variance showed a statistically significant effect of arm positions on mean AGT measurements for the right (F (3, 45) = 51.2666, p < 0.001, effect size = 0.774) and left (F (3, 45) = 51.883, p < 0.001, effect size = 0.776) shoulders. AGT distance was significantly reduced in positions 3 and 4. Within-session intra-class correlation coefficients and the minimum detectable change values ranged from 0.94 to 0.97 and 0.1 to 0.2 cm, respectively, for all four positions. This preliminary study corroborates that supported arm position does reduce the AGT distance in healthy people suggesting ultrasonographic technique has potential to provide objective measurements in clinical management of patients with GHS.

Background: Brachial plexus birth palsy occurs in 0.4 to 4.6 of every 1000 live births, with residual shoulder dysfunction in approximately one third of cases. Clinical measures, such as the Mallet classification, provide no insight into the scapulothoracic and glenohumeral contributions to tested global shoulder movements. This study describes the scapulothoracic and glenohumeral components of shoulder motion during the modified Mallet test., Methods: Twelve children with Erb's palsy (C5-6) and 8 children with extended Erb's palsy (C5-7) were recruited. The unaffected limbs of 6 subjects were also tested. Locations of markers placed on the thorax, humerus, and scapula were recorded in a neutral position and each of the modified Mallet positions. Scapulothoracic, glenohumeral, and humerothoracic helical displacements and acromion process linear displacements were compared between groups., Results: The brachial plexus birth palsy groups exhibited significantly smaller glenohumeral displacements in all modified Mallet positions and significantly larger scapulothoracic displacements in the global external rotation and hand to mouth positions. Discriminant function analysis using only humerothoracic variables correctly classified 76.9% of subjects. Discriminant function analysis incorporating scapulothoracic, glenohumeral, and acromion process displacement variables produced accuracy of 92.6%., Conclusions: Children with brachial plexus birth palsy demonstrated decreased glenohumeral contributions to achieve every modified Mallet position and increased scapulothoracic contribution in two positions compared with the unaffected group. Different scapulothoracic and glenohumeral strategies were identified between groups. Finally, scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification., (Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

Os acromiale is a common finding in shoulder surgery. We review the anatomy, prevalence, pathophysiology, and treatment options for this diagnosis. In addition, we report on a case series of 6 patients with a symptomatic meso os acromiale who were treated with a new technique involving arthroscopic acromioplasty in conjunction with the excision of the acromial nonunion site. We have demonstrated this novel treatment method to be a safe and effective technique in this case series. This arthroscopic partial resection of an os acromiale is considered to be an alternative option for treating a symptomatic meso os acromiale., (Copyright © 2013 Elsevier Inc. All rights reserved.)

This numerical study assesses the influence of an oversized humeral hemiprosthesis with a larger medial offset on the mechanics of the shoulder with cuff tear arthropathy (CTA). Shoulder elevation in the scapular plane is performed, and a Seebauer Type IIa CTA is simulated: a massive rotator cuff tear, a proximal and static migration of the humeral head, and two contacts with friction (glenohumeral and acromiohumeral). The CTA model without a prosthesis (friction coefficient 0.3) is evaluated first as a reference model. Then, three humeral head prosthetic geometries (friction coefficient 0.15) are evaluated: anatomical head, oversized head, and oversized head with a large medial offset. The function of the middle deltoid (i.e. moment arm, applied force, and strength), the contact forces, and the range of motion are studied. The anatomical head, which reduces friction by half, decreases the middle deltoid force (25%) and the contact forces (glenoid 7%; acromion 25%), and increases the range of motion from 41 to 54°. The oversized head increases the moment arm (15%) and the middle deltoid strength (13%), which further decreases the deltoid force (7%) and the contact forces (glenoid 7%; acromion 17%), and increases the range of motion from 54° to 69°. The oversized head with a large medial offset enhances these effects: the moment arm increases by another 3.1%, the deltoid force decreases by another 5% and the acromiohumeral contact force by another 12%, and the range of motion increases from 69° to 84°. These results suggest that increasing the medial offset and oversizing the hemiprosthetic head improve the function of the deltoid, reduce acromial solicitation, and restore elevation to almost 90°., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: Loss of internal rotation range of motion (ROM) on the dominant side is well documented in athletes performing overhead sports activity. This altered motion pattern has been shown to change glenohumeral and scapular kinematics. This could compromise the subacromial space and explain the association between glenohumeral internal rotation deficit (GIRD) and subacromial impingement., Purpose: First, to quantify acromiohumeral distance (AHD) and compare between the dominant and nondominant side in overhead athletes with GIRD of more than 15°. Second, to investigate the effect of a sleeper stretch program on ROM and AHD., Study Design: Controlled laboratory study., Methods: Range of motion was measured with a digital inclinometer and AHD was measured with ultrasound in 62 overhead athletes with GIRD (>15°) at baseline. Differences between sides were analyzed. Athletes were randomly allocated to the stretch (n = 30) or control group (n = 32). The stretch group performed a 6-week sleeper stretch program on the dominant side. Change of range of motion and AHD were measured and analyzed in both groups after 6 weeks., Results: The dominant side showed a significant internal rotation deficit (-24.7° ± 6.3°) and horizontal adduction deficit (-11.8° ± 7.4°) and the dominant side AHD was significantly smaller with the arm at neutral (-0.4 ± 0.6 mm) and at 45° (-0.5 ± 0.8 mm) and 60° (-0.6 ± 0.7 mm) of active abduction compared with the nondominant side. After stretching, significant increase of internal rotation (+13.5° ± 0.8°), horizontal adduction (+10.6° ± 0.9°) ROM and AHD (+0.5 to +0.6mm) was observed at the dominant side of the stretch group compared with prestretching measurements. No significant change of AHD was seen in the nondominant side of the stretch group and in both sides of the control group., Conclusion: The AHD, a 2-dimensional measure for subacromial space, was found to be smaller on the dominant side in athletes with GIRD and was found to increase after a 6-week sleeper stretch program., Clinical Relevance: These findings might provide insight into the relation between GIRD and subacromial impingement but future studies are needed to determine clinical implications.

Objective: This report describes the application of scapular elevation taping (SET) using kinesio tape to elevate the scapula and treat upper trapezius (UT) muscle tenderness in a patient with scapular depression syndrome., Methods: The patient was a 22-year-old man who had scapular depression and severe tenderness of the right UT. We performed SET for 2 months, 4 days a week, for an average of 9 h each day, to provide scapular elevation., Results: At the last assessment, the right superior angle of the scapula and the lateral border of the acromion were slightly elevated compared with the spinous process of the second thoracic vertebra. A chest X-ray showed that the right coracoid process was higher compared to the initial level and that the level of the first ribs was similar on both sides. The pressure-pain threshold in the UT increased from 1 to 8 kg and the tenderness at 3 kg, assessed on a numeric rating scale, decreased from 6 to 0. No tenderness occurred when carrying a bag with the right hand or slinging a bag over the right shoulder., Conclusion: Continuous application of SET may be used as a supplementary method for scapular elevation and reduction in patients with UT tenderness.

Background: shoulder impairments are often associated with altered scapular kinematics. As muscles control scapular movement, functionally altering muscle performance through fatigue may produce scapular kinematics that mimic those of injured patients. The aim of this study was to examine if changes in scapular tilt, rotation and pro/retraction following two different upper extremity fatiguing protocols have any implications with respect to subacromial impingement., Methods: scapular orientation was monitored during posturally constrained static holds (at 0°, 45° and 90° of humeral elevation) before and after two fatiguing protocols, one global and one local. Both protocols are associated with producing changes in shoulder skeletal arrangement., Findings: following the global fatiguing protocol, there was significantly more scapular posterior tilt (P<0.01) and upward rotation (P<0.02), particularly at 90° humeral elevation. No changes in scapular orientation occurred following the local fatiguing protocol., Interpretation: scapular orientation changes following muscle fatigue acted to increase the subacromial space. Thus, the rotator cuff muscles, not the scapular stabilizers, have more influence on actively preventing mechanical subacromial impingement. The lack of evidence of reduction of the subacromial space thus implicates superior humeral head translation as a more likely primary mechanism of the initiation of subacromial impingement., (2010 Elsevier Ltd. All rights reserved.)

Objective: To examine the influence of determinants on the Shoulder Pain and Disability Index., Design: A cross-sectional study. Baseline registrations were applied., Patients: Two hundred patients with subacromial shoulder pain lasting at least 3 months., Methods: A questionnaire consisting of possible determinants, 2 independent variables regarding pain and 2 regarding function, and the outcome measurement. Two multiple regression models (one with and one without the independent variables of pain and function) for the Shoulder Pain and Disability Index, the 2 subscales, and the determinants, were performed., Results: The included determinants explained 29% of the variance of the Shoulder Pain and Disability Index (25% for pain and 33% for disability subscale) with pain medication, emotional distress, flexion, and the hand-behind-back range accounting for 26%. When pain and function were included, the final model explained 65% of the variance, with gender, education and range of flexion showing significance., Conclusion: The determinants explained 26% of the variance of the Shoulder Pain and Disability Index, but explained only a minor proportion when pain and function were included. This supports the Shoulder Pain and Disability Index as a shoulder pain and disability questionnaire.

Hypothesis: Reverse shoulder prostheses depend on deltoid function. An injury to the acromion, either fracture or meso-acromion, or deltoid injury, may affect the outcomes of patients after receiving a reverse shoulder prosthesis., Methods: Four-hundred and fifty-seven consecutive reverse shoulder prostheses were implanted between January 1992 and June 2003 by one of seven surgeons in five separate centers. Forty-one patients were noted to have a pre-operative lesion of the acromion or scapular spine. Twenty-three presented with an os acromiale (meso-acromion). Seventeen had fracture or fragmentation of the acromion. One patient had a pseudarthrosis of the scapular spine., Results: Preoperative acromial pathology, surgical approach, and amount of inferior acromial tilt did not diminished postoperative range of motion, Constant score, or subjective results when compared to patients without acromial pathology. In contrast, the four patients with postoperative acromial spine fractures had inferior results with respect to functional and subjective results., Conclusion: Preoperative acromial lesions are not a contraindication to reverse shoulder arthroplasty. Postoperative fracture of the acromial spine has a significant effect on results and treatment is uncertain.

Several intrinsic and extrinsic factors have been advocated in the pathogenesis of rotator cuff tears, but it is still unclear whether the origin of the tear is related to tendon degeneration itself or induced by several morphologic changes. The purpose of this study is to determine the relationship between the acromial coverage of the humeral head and the presence of a cuff tear. We evaluated 148 shoulders, including 45 that underwent surgical rotator cuff repair (group I), 26 with documented rotator cuff tears treated conservatively (group II), and 77 with no cuff pathology as a control group (group III). The mean acromial coverage index was 0.68 in group I, 0.72 in group II, and 0.59 in group III, giving a highly significant difference (P < .0001) between the control group and both cuff tear groups. Patients with a cuff tear have a significantly higher acromial coverage index than the control group.

Successful design of components for total shoulder arthroplasty has proven to be challenging. This is because of the difficulties in maintaining fixation of the component that inserts into the scapula; i.e., the glenoid component. Glenoid components that are fixated to both the glenoid and acromion (a long process extending medially on the dorsal aspect of the scapula) have the possible advantage of greater stability over those that are fixated to the glenoid alone. In this study, a finite element analysis is used to investigate whether or not acromion fixation is advantageous for glenoid components. Full muscle loading and joint reaction forces are included in the finite element model. Reflective photoelasticity of five scapulae is used to obtain experimental data to compare with results from the finite element analysis, and it confirms the structural behaviour of the finite element model. When implanted with an acromion-fixated prosthesis, it is found that high unphysiological stresses occur in the scapula bone, and that stresses in the fixation are not reduced. Very high stresses are predicted in that part of the prosthesis which connects the acromion to the glenoid. It is found that the very high stresses are partly in response to the muscle and joint reaction forces acting at the acromion. It is concluded that, because of the relatively high forces acting at the acromion, fixation to it may not be the way forward in glenoid component design.

Unlabelled: We sought to determine how various types of full-thickness rotator cuff tears, fatty degeneration of the rotator cuff muscles, duration of symptoms, and mechanism of injury affect the sizes of the acromiohumeral and coracohumeral intervals. We studied 206 shoulders with rotator cuff tears that had surgical treatment. The acromiohumeral interval (anteroposterior radiograph) and the coracohumeral interval (computed tomogram) were measured on preoperative imaging studies. An abnormal acromiohumeral interval was associated with multiple-tendon rotator cuff tears involving the infraspinatus, fatty degeneration of the supraspinatus or infraspinatus, and duration of symptoms longer than 5 years. An abnormal coracohumeral interval was associated with a combined tear of the supraspinatus and subscapularis and fatty degeneration of the infraspinatus or subscapularis. Fatty degeneration of the infraspinatus therefore was associated with an abnormal acromiohumeral interval and an abnormal coracohumeral interval. Evaluation of a patient who has a diminished acromiohumeral or coracohumeral interval should involve examination with computed tomography or magnetic resonance imaging of the rotator cuff tendons to determine the type of tear and of the rotator cuff muscles to determine the degree of fatty degeneration., Level of Evidence: Diagnostic study, Level II-1 (development of diagnostic criteria on basis of consecutive patients--with universally applied reference "gold" standard). See the Guidelines for Authors for a complete description of levels of evidence.

Objectives: Failure of fusion of the secondary centers of ossification of the acromial apophyses is a pathology that should be included in the differential diagnosis of shoulder pain and subacromial impingement syndrome. Mobility of the meso-acromion is of particular importance in choosing the appropriate treatment. This study presents a new arthroscopic method to evaluate the mobility of os acromiale., Methods: We presented the arthroscopic evaluation and surgical treatment of three women (mean age 43.3 years; range 34 to 53 years) with shoulder pain and a radiographically confirmed meso-acromiale. The Neer and Hawkins impingement signs were positive and palpation over the acromion gave rise to pain. Axillary radiographs showed a meso-acromion in all the affected shoulders. Magnetic resonance imaging showed a rotator cuff tear in one patient. During arthroscopic examination the motility of the meso-acromion was dynamically observed in the subacromial region and the rotator cuff tear was repaired. Acromioplasty was not performed. Following removal of pseudarthrotic areas, the mobile meso-acromion was fixed with a cerclage wire, two cannulated screws and bone grafting, followed by a tension-band configuration. The mean follow-up was five years (range 3 to 6 years)., Results: Union occurred in all the patients. None of the patients had shoulder pain at rest or during activities. When compared with the normal side, the range of motion and the strength of the shoulder were normal in all the patients, with Constant scores being 89, 96, and 98, respectively., Conclusion: Identification of the type of os acromiale is important for the treatment plan. The meso-acromion is particularly important because of its greater size and its role in narrowing the subacromial space. It is necessary to determine whether the meso-acromion fragment is mobile. Dynamic arthroscopic examination offers significant help in this respect.

In order to determine whether adhesion of the subacromial bursa leads to impingement, we measured the subacromial contact pressures before and after release of adhesion of this bursa. 18 shoulders with cuff tears and adhesion of the subacromial bursa were evaluated in 8 male and 10 female patients, of mean age 62 (53-71) years and who had no particular limitation of shoulder motion. We recorded subacromial pressures using a very sensitive film inserted under the acromion during surgery. In passive scapular plane elevation (scaption) at 100 degrees, the mean subacromial contact pressure and area declined from 1.43 (SD 0.23) MPa before release to 1.14 (SD 0.35) MPa after release (p < 0.001), and from 163 (SD 81) mm2 before release to 80 (SD 46) mm2 after release (p < 0.001), respectively. We suggest that adhesion of the subacromial bursa increases impingement between the acromion and the insertion of rotator cuff tendons.

Purpose: Strengthening of the shoulder depressors is an important component in the treatment of impingement syndrome. However, the quantitative effect of various muscle forces on the width of the subacromial space has never been demonstrated in vivo. Therefore, the purpose of this study was to analyze the influence of adducting and abducting muscle forces on the subacromial space width in healthy volunteers in various arm positions., Methods: The shoulders of 12 healthy volunteers were imaged with an open MR system at 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 150 degrees of arm elevation under both isometric adducting and abducting muscle activity (15 N). After segmentation and three-dimensional reconstruction of anatomically relevant structures, the minimal spatial acromiohumeral and claviculohumeral distances were quantified., Results: Adducting muscle forces led to a significant increase of the acromiohumeral distance in all arm positions (P < 0.01), varying from 32% (30 degrees ) to 138% (90 degrees ) relative to abducting muscle forces. The claviculohumeral distance showed an increase of 9% (30 degrees ) to 24% (90 degrees ), this increase being also statistically significant at all positions (P < 0.05). During elevation of the arm (30-120 degrees ), the absolute subacromial space width was reduced significantly (P = 0.001) by 30% under isometric contraction of the adductors compared with 53% (P = 0.001) under activation of the abductors., Conclusion: This in vivo study shows for the first time that adducting muscle forces lead to a significant increase of the subacromial space width compared with abducting muscle activity. In the future, this technique and data can be used to objectively quantify the effect of physical therapy protocols focused on increasing the depressor effect of adducting muscles in the postoperative and conservative treatment of impingement syndrome of the shoulder.

In this study we analyzed the acromial spurs of 15 patients with impingement syndrome undergoing open rotator cuff repair. Mineral apposition analysis and quantitative cytochemical techniques for glucose-6-phosphate dehydrogenase (G6PD) activity (pentose phosphate pathway), alkaline phosphatase (ALP) activity (osteoblast activity), and tartrate-resistant acid phosphatase (TRAP) activity (osteoclast phenotype) were used to examine the distribution and level of activity of selected marker enzymes within the acromial spur insertion into the coracoacromial ligament in order to establish whether local behavior of bone cells is consistent with the proposed secondary development of the acromial spur. Our results indicate that G6PD and ALP activity was higher in osteoblasts on the inferior surface compared with the superior surface of the acromial spur in all patients (P <.001). This area correlated to the most intense area of mineral apposition shown by dual tetracycline labeling. TRAP activity revealed a heterogeneous distribution within the samples. A greater G6PD activity per cell (mean increase of 87%) was seen at the tip compared with that in post- and pre-tip zones within the coronal plane (P <.0002). The qualitative and quantitative enzyme analyses show that the acromial insertion of the coracoacromial ligament is actively involved in bone turnover. The spatial distribution patterns of metabolically active bone-forming osteoblastic cells compared with a heterogeneous distribution of TRAP-positive osteoclasts provide evidence of bone remodeling consistent with the morphologic contours of the acromial enthesis. The sites of oxytetracycline labeling appear to correlate with the sites of high ALP and G6PD activity, which supports the concept of spur formation being a secondary phenomenon in the presence of established rotator cuff tears.

We recorded pressures in the subacromial space with various degrees of humeral abduction. The recordings were made during open surgery and under general anaesthesia using a 2-mm-thick piezo-electric pressure transducer. The pressures were recorded in 14 patients with shoulder impingement syndrome (Neer's stage II) and in eight patients with acromioclavicular dislocation serving as controls. The pressures were higher in the impingement group than in the control group. In both groups the highest pressures were recorded antero-laterally under acromion. In patients with impingement syndrome, the pressures increased significantly with abduction.

Purpose: The purpose of this study was to investigate the difference in contact geometry at the undersurface of acromion in shoulders with and without a rotator cuff (RC) tear., Type of Study: Case-control study., Methods: Forty fresh cadaveric shoulders (average age at death, 61 years) without gross osteoarthritic changes were divided into the intact RC group (n = 20) and the RC tear group (n = 20). Clinical impingement was simulated by compressing the humeral head and the intact portion of the RC against the coracoacromial arch with an axial compressive force of 25 kg while the humerus was held abducted 20 degrees in the scapular plane. The contact pattern between the acromion and the RC was measured with Fuji Prescale super low-pressure-sensitive film (Fuji Photo Film Co, Ltd, Tokyo, Japan). The imprint image was analyzed using Global Lab image software (Automatix, Marlboro, MA)., Results: The percentage of the maximum anteroposterior dimension of the imprint on Fuji film to the anteroposterior diameter of the acromial undersurface was 29% +/- 9% in intact RC shoulders, and 39% +/- 13% in shoulders with an RC tear (P >.05). The percentage of the maximum mediolateral dimension of the imprint to the mediolateral diameter of the corresponding part of the acromial undersurface was 27% +/- 12% in intact RC shoulders, and 48% +/- 11% in shoulders with an RC tear. This difference was statistically significant (P <.005)., Conclusions: The contact geometry of the acromial undersurface with the underlying RC in the anteroposterior dimension, which might be related to the appearance in supraspinatus outlet view, was not significantly different between shoulders with and without an RC tear. These findings suggest that factors other than acromial shape play a significant role in the pathogenesis of RC tears. The implication regarding the role of acromioplasty remains to be clarified.

Objective: Evaluation of the functional results of the Delta 3 inverted shoulder prosthesis and determination of a radio-anatomical index predictive of best functional outcome., Patients and Methods: Retrospective analysis of 19 patients (21 shoulders). Clinical (pain, satisfaction, amplitudes, Constant index) and radiological (acromio-epiphyseal distance) evaluation at a mean follow up of 13.6 months., Results: Outcomes concerning pain, quality of life and Constant index were good and similar to other series. Few complications were observed. An increase of the acromio-epiphyseal distance of 33 to 50% compared to the non operated side is associated with a good functional result., Conclusion: Our results confirm those of other series and show that Delta 3 inverted prosthesis is an efficient therapeutic alternative in arthropathy with rotator cuff tears. Rehabilitation is fairly short and easy. The increase of the acromio-epiphyseal distance determines the tension of the deltoid muscle and could predict a favorable outcome.

In 14 rabbits we determined the origin of the cells effecting healing of the tendon of supraspinatus inserted into a bony trough. After two weeks both the cellularity of the underlying bone and the thickness of the subacromial bursa were significantly increased in the operated compared with the control shoulders. The cellularity of the stump of the tendon, however, was significantly decreased in the operated shoulders. In this model, both the underlying bone and the subacromial bursa but not the stump of the tendon contributed to the process of repair. We conclude that the medial stump should be debrided judiciously but that cutting back to bleeding tissue is not necessary during repair of the rotator cuff. Moreover, great care should be taken to preserve the subacromial bursa since it seems to play an important role in the healing process.

The recovery of shoulder muscle strength after open acromioplasty was evaluated in 48 patients (27 male, 21 female, mean age 44.3 years) who had undergone open acromioplasty because of stage II impingement syndrome. The isometric strengths of flexion, abduction and external rotation were measured before the operation and at 3, 6 and 12 months postoperatively. The mean preoperative flexion strength of the involved shoulder was 72.6% of that of the uninvolved shoulder, and this increased to 77.1% by 3 months post operation, to 88.3% at 6 and to 88.3% at 12 months. Corresponding abduction strengths were 68.4%, 80.4%, 88.7% and 91.0% and the external rotation strengths were 75.1%, 77.4%, 95.1% and 93.5%, respectively. These recoveries were markedly improved when the cases with poor subjective results at 1 year were not considered. The low preoperative strengths were more pronounced in women than in men, but recovery was better in women. It is concluded that shoulder muscle strengths recover to near normal in 1 year after open acromioplasty.

Purpose: The impingement of subacromial structures has been proposed as a major cause of the shoulder problems experienced by athletes who use repetitive overhead actions. The purpose of this study was to develop a noninvasive method to identify instances at which the shoulder was experiencing impingement during front-crawl swimming., Methods: Shoulder impingement has been reported to occur when an arm is: (a) elevated above shoulder height while being rotated internally; and (b) forcibly elevated at, or beyond, the maximum active elevation angle. In this study shoulder configurations that satisfied the above two conditions were sought throughout the functional range of each shoulder; and a boundary that distinguished configurations that would cause shoulder impingement was defined. The shoulder movements exhibited during performance of the front-crawl stroke were measured using three-dimensional videography and compared with the boundary defined for each shoulder. The shoulder was considered to experience impingement if the shoulder configuration observed exceeded the boundary defined for that shoulder., Results: For a male collegiate swimmer, impingement occurred for 12% of the stroke time for each shoulder., Conclusions: The analysis permitted the identification of the instances at which the shoulders were experiencing impingement during the front-crawl swimming. In this study, the measurement of the boundary was based entirely upon the mechanism of impingement described in the literature. Further studies are needed to confirm the occurrence of impingement by means of advanced visualization techniques, such as magnetic resonance imaging (MRI) and ultrasonogram.