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Range of motion (ROM) and prevention of notching remain a challenge for reverse shoulder arthroplasty (RSA). Both may be affected by the morphology of the scapula. The purpose of this study was to define anteroinferior (a) and posteroinferior (p) relevant scapular neck offset (RSNO) and to examine the hypothesis that pRSNO is significantly smaller than aRSNO, and influences rigid body motion (RBM). Adapting glenosphere implantation strategies may therefore be of value.In this computer model study, we used deidentified computed tomographic scans of 22 patients (11 male and 11 female; mean age: 72.9 years) with massive cuff tears without joint space narrowing. Eight RSA glenoid configurations were tested with a constant neck-shaft angle (145°). Two baseplate types (25 mm; 25 + 3 mm lateralized) and 4 glenospheres (GS) (36 mm; 36 +2 mm of eccentricity; 39 mm; 39 + 3 mm) were used. RSNO was defined as the standardized measurement of the horizontal distance from the inferior extent of the GS to the bony margin of the scapula after baseplate positioning (flush to inferior glenoid extent; neutral position: 0° inclination and 0° version-both software computed).There was a highly significant difference between pRSNO and aRSNO for both genders (P .001). pRSNO was always smaller than aRSNO. pRSNO was strongly correlated with external rotation (ERO: 0.84) and extension (EXT: 0.74) and moderately correlated with global ROM (GROM: 0.68). There was a moderately strong correlation between aRSNO and internal rotation (IRO: 0.69). pRSNO was strongly correlated with aRSNO, EXT, ERO, IRO, adduction (ADD) and GROM (0.82, 0.72, 0,8, 0.71, 0.82, 0.76) in female patients and with EXT and ERO (0.82, 0.89) in male patients. The median pRSNO allowing for at least 45° ERO and 40° EXT was 14.2 mm for men and 13.8 mm for women. For all patients and models, pRSNO ≥14 mm increased EXT, ERO, and GROM significantly compared with pRSNO14 mm (P .001). The combination of lateralization and inferior overhang (eccentricity) led to the most significant increase of pRSNO for each GS size (P .001).This is one of the first RSA modeling studies evaluating nonarthritic glenoids of both genders. The lateral scapular extent to glenoid relationship is asymmetric. pRSNO is always smaller than aRSNO for both genders and was a critical variable for EXT and ERO, demonstrating additional strong correlation with aRSNO, IRO, ADD, and GROM in female patients. pRSNO ≥14 mm was a safe value to prevent friction-type impingement. Combining increased glenosphere size, lateralization, and inferior overhang gives the best results in this computer-simulated setting.

Background The purpose of the study was to identify genetic variants associated with rotator cuff disease by performing a genome-wide association study (GWAS) for shoulder impingement using the UK Biobank (UKB) cohort and then combining the GWAS data with a prior GWAS for rotator cuff tears. The loci identified by the GWAS and meta-analysis were examined for changes in expression following rotator cuff tearing using RNA sequencing. Methods A GWAS was performed using data from UKB with 3864 cases of shoulder impingement. The summary statistics from shoulder impingement and a prior study on rotator cuff tears were combined in a meta-analysis. Also, the previous association of 2 single-nucleotide polymorphisms (SNPs) with shoulder impingement from a published GWAS using the UKB was tested. Rotator cuff tendon biopsies were obtained from 24 patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair (cases) and 9 patients who underwent open reduction internal fixation for a proximal humeral fracture (controls). Total RNA was extracted and differential gene expression was measured by RNA sequencing for genes with variants associated with rotator cuff tearing. Results The shoulder impingement GWAS identified 4 new loci: LOC100506457, LSP1P3, LOC100506207, and MIS18BP1/LINC00871. Combining data with a prior GWAS for rotator cuff tears in a meta-analysis resulted in the identification of an additional 7 loci: SLC39A8/UBE2D3, C5orf63, ASTN2, STK24, FRMPD4, ACOT9/SAT1, and LINC00890/ALG13. Many of the identified loci have known biologic functions or prior associations with diseases, suggesting possible biologic pathways leading to rotator cuff disease. RNA sequencing experiments show that expression of STK24 increases whereas expression of SAT1 and UBE2D3 decreases following rotator cuff tearing. Two SNPs previously reported to show an association with shoulder impingement from a prior UKB GWAS were not validated in our study. Conclusion This is the first GWAS for shoulder impingement in which new data from UKB enabled the identification of 4 loci showing a genetic association. A meta-analysis with a prior GWAS for rotator cuff tearing identified an additional 7 loci. The known biologic roles of many of the 11 loci suggest plausible biologic mechanisms underlying the etiology of rotator cuff disease. The risk alleles from each of the genetic loci can be used to assess the risk for rotator cuff disease in individual patients, enabling preventative or restorative actions via personalized medicine.

Background Therapeutic exercise for scapular muscles is suggested to be effective in reducing shoulder pain in patients with rotator cuff disorders, whereas its effectiveness on scapular position and motion has remained unclear. Therefore, the aim of this systematic review was to investigate whether exercise therapy improves scapular position and motion in individuals with scapular dyskinesis. Methods This study is a wide systematic review including any type of clinical trial in which the effect of any type of therapeutic exercise, including scapular muscle strengthening, stretching, and scapular stabilization exercise, is investigated in adult participants. Results Twenty studies were included in this systematic review. Studies were categorized on the basis of the techniques they used to measure scapular position and motion and the included participants. Methodologic quality of the studies was assessed by the Cochrane tool of assessing the risk of bias. Eight studies used 3-dimensional techniques for measuring scapular motions. Among them, 5 studies showed significant effects of exercise on scapular motion, of which 3 studies investigated individuals with subacromial impingement syndrome (SIS). The other 12 studies used 2-dimensional measurement techniques, of which 8 studies reported significant effects of exercise on scapular position and motion both in SIS patients and in asymptomatic individuals. However, their methodologic quality was debatable. Therefore, there was conflicting evidence for the effect of exercise on scapular dyskinesis. Conclusion There is a lack of evidence for beneficial effects of exercise in improving scapular position and motion in individuals with scapular dyskinesis. However, exercise is beneficial in reducing pain and disability in individuals with SIS.

Subacromial impingement of the rotator cuff caused by variations in acromial anatomy or altered glenohumeral kinematics leads to inflammation and degeneration of the rotator cuff, ultimately contributing to the development of tendinopathy. However, the underlying cellular and molecular changes in the impinged tendon remain poorly understood. Because the rat is an accepted model for rotator cuff studies, we have developed a rat model to study rotator cuff tendinopathy.Forty-four adult male Sprague-Dawley rats were allocated to one of 4 study groups: intact control group (group 1, n = 11); bilateral subacromial surgical clip placement to induce supraspinatus impingement for 2 weeks (group 2, n = 11), 4 weeks (group 3, n = 11), and 8 weeks (group 4, n = 11). Bilateral shoulder specimens were harvested for biomechanical testing, histology, and quantitative real-time polymerase chain reaction (qRT-PCR) analysis.Radiography confirmed that all microvascular clips remained in stable position in the subacromial space. Gross inspection of supraspinatus tendon specimens in the impingement groups revealed changes in tendon morphology at the enthesis and midsubstance. Biomechanical evaluation demonstrated decreased supraspinatus tendon failure force and tissue stiffness at all time points compared with control tendons. Semiquantitative scoring of histologic specimens demonstrated significant, persistent tendinopathic changes over 8 weeks. qRT-PCR analysis of impinged tendon specimens demonstrated upregulation of gene expression for Col3 and Mmp14 in the impingement groups compared with control groups. In muscle samples, significant upregulation was seen in the expression of genes that are commonly associated with muscle atrophy (MuRF1 and Ube2b) and fatty infiltration (Fabp4, Pparg2, and Klf15).This new rat subacromial impingement model creates cellular and molecular changes consistent with the development of rotator cuff tendinopathy. The results of this study may serve as a baseline for future investigation.

Background Shoulder impingement syndrome is considered to be associated with an altered muscular activity, which is related to strategy changes in the movement plan. The present study aimed to investigate the differences in timing and intensity of activity of shoulder girdle muscles while performing a forehand topspin loop between elite table tennis players with and without shoulder impingement syndrome. The timing and activity amplitude of these shoulder girdle muscles have not been evaluated in other studies in table tennis elite athletes. Methods Activation timing and activity levels of the upper trapezius, lower trapezius, and serratus anterior, anterior deltoid, supraspinatus, and biceps brachii muscles were measured in 30 table tennis players (Premier League tournament level or higher) with shoulder impingement syndrome and compared with 30 same-level healthy players while performing the forehand topspin loop. Results The results indicated that the activity levels of the serratus anterior (P = .007) and supraspinatus (P = .001) muscles significantly decreased; however, the activity level of the upper trapezius significantly increased in the impingement compared with the healthy group (P = .009). The serratus anterior (P = .001) was activated significantly later, but the upper trapezius (P = .004) was activated significantly earlier in the impingement group. Conclusion Results of the present study support the theory that the activation and sequence of recruiting of the shoulder muscles are altered in people with impingement symptoms, suggesting that impingement syndrome may be associated with disturbed timing and activity level of shoulder girdle muscles.

Background The Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Computer Adaptive Test (CAT) was previously validated for rotator cuff disease and shoulder instability. This study evaluated the psychometric properties of the PROMIS Physical Function (PF) CAT, PROMIS Pain Interference (PI) CAT, and the American Shoulder and Elbow Surgeons (ASES) Shoulder Function Score for subacromial impingement syndrome. Methods PROMIS PF CAT, PI CAT, and ASES (Pain, Function, Total) were collected on all visits for 2 surgeons between January 2016 and August 2016. New patients, aged 18 years and older, were selected by International Classification of Diseases code for impingement syndrome of the shoulder. The mean number of questions answered determined efficiency. Person-item maps were created to determine ceiling and floor effects as well as person reliability. Convergent validity was determined by comparison of PROMIS domains to ASES scores with Pearson correlations. Results For PROMIS PF CAT, the mean number of items answered was 4.54 (range 4-12). The ceiling effect was 1.56%, and the floor effect was 3.13%. The person reliability was 0.94. Pearson correlation coefficients between the PF CAT and ASES were 0.664 (ASES Function), 0.426 (ASES Pain), and 0.649 (ASES Total). For PROMIS PI CAT, the mean number of items answered was 4.27 (range 3-11). The ceiling effect was 4.69%, and the floor effect was 8.33%. The person reliability was 0.92. Pearson correlation coefficients between the PI CAT and ASES were: 0.667 (ASES Function), 0.594 (ASES Pain), and 0.729 (ASES Total). Conclusions The psychometric properties of PROMIS PF and PI CATs were favorable for subacromial impingement syndrome.

Background: Patients with subacromial pain syndrome (SAPS) frequently present with coexisting psychosocial problems; however, whether this also associates with long-term outcome is currently unknown. We assessed whether psychosocial functioning in patients with SAPS is associated with persistence of complaints after 4 years of routine care.Methods: In a longitudinal study, 34 patients with SAPS were selected after clinical and radiologic evaluation and assessed at baseline and after 4 years. For the assessment of psychosocial functioning, the RAND-36 questionnaire domains of social functioning, role limitations due to emotional problems, mental health, vitality, and general health were evaluated. Complaint persistence at follow-up was assessed by (1) an anchor question (reduced, persistent, or increased symptoms), (2) change in pain (change in visual analog scale score), and (3) change in quality of life (change in Western Ontario Rotator Cuff index score).Results: Lower baseline mental health (odds ratio [OR], 0.92; 95% confidence interval [CI], 0.85-0.98; P = .013), vitality (OR, 0.90; 95% CI, 0.83-0.98; P = .011), and general health (OR, 0.93; 95% CI, 0.88-0.98; P = .009) were associated with persistent complaints as reported by the anchor question, change in visual analog scale score, and change in Western Ontario Rotator Cuff index score.Conclusions: Evaluating psychosocial functioning parallel to physical complaints is currently not standard procedure in the treatment of SAPS. In this study, we showed that factors related to psychosocial functioning are associated with long-term persistence of complaints in SAPS. Future studies may investigate whether a multimodal treatment with assessment of psychosocial functioning may facilitate pain relief and recovery in SAPS. (c) 2020 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Background Competitive swimmers incur shoulder pain and injury. Physical characteristics such as shoulder range of motion (ROM) and endurance and tissue adaptations such as posterior capsule thickness (PCT) may be risk factors in addition to high training volume. Hypothesis/Purpose 1) To identify the most provocative special test and prevalence of positive special tests for shoulder impingement tests in a group of collegiate swimmers, (2) to assess shoulder pain and disability, internal rotation (IR) and external rotation, and horizontal adduction (HADD) ROM and posterior shoulder endurance longitudinally over a competitive collegiate season, and (3) determine if there is a relationship between swimming yardage, supraspinatus tendon organization, and PCT. Methods Thirty Division III swimmers were tested poolside at the beginning (T1), middle (T2), and end (T3) of their season. Dependent variables included pain and disability, shoulder ROM, Posterior Shoulder Endurance Test (PSET) value, and PCT. Analyses of variance with follow-up t tests compared measures over time, and Pearson correlation coefficients were performed. Results Despite increased swimming yardage, disability was reduced from T1 to T3 (P = .003). There was a reduction in bilateral IR and HADD ROM from T1 to T3. PSET values increased on the right from T1 to T3 (P = .014). There was a significant positive correlation between swimming yardage at T1 and T2 and PCT at T3 (P = .034, P = .028). Conclusion A loss of shoulder IR and HADD was observed across the season concurrent with less swimming-related disability, which may indicate a favorable adaptation. Improved PSET scores over the season is consistent with prior research linking endurance and less pain and disability.

Background Defining a simple and reliable classification for acromial and bursal impingement lesions is necessary to standardize terminology, to improve communication, and to allow better evaluation of the proper treatment of impingement lesions and rotator cuff tears. The purpose of this study was to assess orthopedic surgeons' intraobserver and interobserver reliability of the Copeland-Levy classification. Methods Six fellowship-trained orthopedic surgeons reviewed shoulder arthroscopy videos of 69 consecutive patients who underwent shoulder arthroscopy for rotator cuff tear repair or subacromial decompression. The surgeons were asked to classify impingement lesions according to the Copeland-Levy classification. One month afterward, the surgeons were requested to repeat the evaluation of the same impingement lesions. Intraobserver reliability was calculated using Cohen's weighted κ. Interobserver reliability was calculated using Kendall's W. Results Overall intraobserver reliability for acromial and bursal lesions was κ = 0.86 (95% confidence interval, 0.82-0.9) and κ = 0.97 (95% confidence interval, 0.95-0.98), respectively. Interobserver reliability for acromial and bursal lesions was W = 0.87 and W = 0.92, respectively. Conclusion Intraobserver and interobserver reliability of the Copeland-Levy classification among senior orthopedic surgeons is excellent. Hence, we suggest the Copeland-Levy classification be used to standardize terminology of the subacromial impingement lesion.

Background A previously validated finite element modeling approach was used to determine how changes in glenoid component version and polyethylene liner rotation within the humeral component affect the arm abduction angle at which impingement between the inferior glenoid and the polyethylene liner occurs as well as the amount of subluxation generated by that impingement. Materials and Methods Five glenoid component versions (5° anteversion; neutral; 5°, 10°, and 20° retroversion) and 7 polyethylene liner rotations (20° and 10° anterior; neutral; 10°, 20°, 30°, and 40° posterior) were considered, resulting in 35 different clinically representative models. The humerus was internally and externally rotated and extended and flexed, and the resulting impingement and subluxation were measured. To further analyze more global trends and to identify implantations least prone to subluxation, polyethylene liner rotation was additionally varied in coarser 30° increments across the entire 360° range. Results All subluxation caused by impingement occurred during external rotation and extension, and external rotation produced nearly 10-fold more subluxation than extension. Neutral glenoid component version was associated with the least amount of subluxation for all polyethylene liner rotations. Posteriorly rotated polyethylene liners, which place the thick inferior region of the component away from the scapula, produced the least amount of subluxation. The 90° and 120° posterior liner rotations produced no subluxation, whereas the 30° and 60° anterior liner rotations produced the greatest amount of subluxation. Conclusion These results indicate that rotating modern radially asymmetric humeral polyethylene liners posteriorly can reduce the risk of subluxation leading to dislocation and increase external rotation range of motion.

Background This study aimed to determine the most appropriate angle and moving direction of the arm for improving coordination of the periscapular muscles, including the serratus anterior (SA), upper trapezius (UT), middle trapezius (MT), and lower trapezius (LT). Methods Muscle activation amplitudes were evaluated in the SA, UT, MT, and LT in 11 healthy subjects by use of surface electromyography. The subjects were asked to maintain the arm position at 5 elevated positions with maximal effort against applied manual forces, which were directed from upper to lower (test 1), lower to upper (test 2), posterior to anterior in the frontal plane and lateral to medial in the sagittal plane (test 3), and anterior to posterior in the frontal plane and medial to lateral in the sagittal plane (test 4). The relative activity of the UT with respect to the SA, MT, and LT was calculated, resulting in the UT/SA, UT/MT, and UT/LT ratios. Results Test 4 in all positions but 150° of elevation in the frontal plane showed high activity of the SA with a low UT/SA ratio. High MT activity with a low UT/MT ratio was observed during test 3 at the 90° elevated position, whereas high LT activity without UT hyperactivation was not found. Discussion To strengthen the periscapular muscles in the balanced condition, horizontal adduction is recommended for the SA. Horizontal abduction at the 90° elevated position should be effective for the MT. Because no technique in this study was effective for the LT, further studies are needed.

Background Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography. Methods Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver–angle combinations. Results The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°. Conclusions This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo.

Patients with subacromial impingement were reported to show abnormal scapular positions during shoulder elevation. However, the relationship between the scapular positions and subacromial impingement is unclear. The purpose of this study was to biomechanically determine the effect of scapular position on subacromial contact behavior by using fresh frozen cadavers.The peak contact pressure on the coracoacromial arch was measured with a flexible tactile force sensor in 9 fresh frozen cadaver shoulders. The measurement was performed during passive glenohumeral elevation in the scapular plane ranging from 30° to 75°. The scapular downward and internal rotations and anterior tilt were simulated by tilting the scapula in 5° increments up to 20°. The measurement was also performed with combination of scapular downward and internal rotations and anterior tilt positions.The peak contact pressure decreased linearly with anterior tilt, and a significant difference between neutral scapular position (1.06 ± 0.89 MPa) and anterior tilt by 20° (0.46 ± 0.18 MPa) was observed (P .05). However, the scapular positioning in the other directions did not change the peak contact pressure significantly. Furthermore, any combination of abnormal scapular positions did not affect peak contact pressure significantly.Scapular anterior tilt decreased peak contact pressure during passive shoulder elevation. In addition, scapular downward and internal rotations had little effect on peak contact pressure. The abnormal scapular motion reported in previous studies might not be directly related to symptoms caused by subacromial impingement.

The strength of the shoulder protractors and retractors may be compromised in individuals with winged scapula (IwWS). However, no standard approach to measuring the strength of these muscles has been described. The aim of this study was to study the intra-rater and inter-rater reproducibility of a fixed-base isometric dynamometer and to describe cutoff scores for clinically meaningful change for protraction and retraction isometric strength.Twice during a week, 20 normal subjects and 20 IwWS were tested by 2 independent raters.IwWS were significantly weaker (P .001) than control subjects in their protraction and retraction isometric strength. Excellent intra-rater and inter-rater correlations were obtained in most combinations, leading to low cutoff scores for meaningful change expressed in terms of the smallest real difference.When it is properly used, the technique described in this paper is recommended as an effective clinical tool for the quantitative assessment of protraction and retraction isometric strength, both for status determination and for monitoring of change in IwWS during and after rehabilitation.

Background Coracoid impingement syndrome is an increasingly recognized etiology of anterior shoulder pain. Numerus studies have documented the coracohumeral distance (CHD) as a primary or secondary measurement in symptomatic individuals, but there lacks an evaluation of CHD in a large cohort of asymptomatic individuals. The purpose of this study was to quantify a normative distribution of the CHD in a large cohort of healthy, asymptomatic subjects with no history of impingement or shoulder instability. Methods Incoming first-year students in the United States Military Academy were offered enrollment in this study as part of a prospective cohort to assess the normal anatomic relationships of the shoulder girdle. Magnetic resonance images were obtained, and a board-certified, fellowship-trained musculoskeletal radiologist performed measurements of the smallest distance from the coracoid to the humeral head on axial images. Results Magnetic resonance images of 714 subjects were available for analysis, including 630 males and 84 females, with a total of 1120 individual shoulders with images of adequate quality. The mean CHD for all shoulders imaged was 13.7 mm. The mean CHD in male shoulders was 13.8 mm, and in female subjects the average was 12.4 mm. Conclusions This study is the largest of its kind to evaluate the CHD in asymptomatic, healthy shoulders to date and demonstrates a mean CHD of 13.7 mm for all subjects. This information can help to standardize “normal” ranges and act as a comparison for future work, when taken in the context of age and imaging in neutral rotation.

The gross pathology of the acromial undersurface in shoulders with rotator cuff tears with subacromial impingement is not completely understood. Many researchers have focused on damage to the anterior one-third area of the acromial undersurface, but few have studied the middle and posterior one-third areas. The purpose of this study was to clarify where and what damage occurs at the acromial undersurface in patients with rotator cuff tears.We performed arthroscopic shoulder (n = 182, all with rotator cuff tears; mean age, 64.9 ± 8.4 years) and cadaveric shoulder (n = 23, 14 intact cuffs and 9 rotator cuff tears; mean age, 74.8 years) evaluations to observe the extent and degree of damage to the acromial undersurface. We statistically analyzed the association between the severity of the damage to the acromial undersurface (assessed using the Copeland-Levy classification as A0, normal; A1, minor scuffing; A2, major damage; or A3, visualization of bare bone area) and rotator cuff tear size (assessed using the classification of DeOrio and Cofield as partial; small,1 cm; medium, 1-3 cm; or large or massive,3 cm).The anterior, middle, and posterior one-thirds of the acromial undersurface were somewhat damaged (class A1-A3) in 92.6%, 90.1%, and 78.6% of shoulders with rotator cuff tears, respectively, according to arthroscopic evaluation. Increasing cuff tear size was significantly associated with worsening degree of damage to the acromial undersurface (P.001). In the 9 cadaveric shoulders with rotator cuff tears, class A1-A3 damage was identified in the anterior one-third area in 100%, in the middle one-third area in 88.9%, and in the posterior one-third area in 33.3%. In the 14 cadaveric shoulders with a normal rotator cuff, class A1-A3 damage was identified in the anterior one-third area in 35.7%, in the middle one-third area in 14.3%, and in the posterior one-third area in 0.71%.Damage to the acromial undersurface in patients with rotator cuff tears occurred at the middle, posterior, and anterior one-third areas, and the degree of damage was related to cuff tear size. Surgeons should evaluate the entire acromial undersurface to check for subacromial impingement damage at the middle and posterior one-third areas as well as the anterior one-third area of the acromial undersurface; this might aid in the treatment of patients with rotator cuff disease or subacromial impingement syndrome.

Background Subacromial analgesia (SAA) is hypothesized to reduce pain after arthroscopic shoulder surgery by delivering a continuous infusion of local anesthetic directly to the surgical site. The purpose of this systematic review and meta-analysis was to evaluate the efficacy of SAA vs. placebo for pain relief after arthroscopic subacromial shoulder procedures. Methods MEDLINE, Embase, PubMed, and the Cochrane Central Register of Controlled Trials were searched for randomized controlled trials comparing SAA with placebo after arthroscopic shoulder surgery. Outcomes collected included pain scores (converted to equivalent ordinal visual analog scores; minimal clinically important difference 1.4 cm), oral morphine equivalents used postoperatively, and catheter-related complications. Meta-analysis was performed via a random-effects model. Included trials underwent a risk of bias and quality of evidence assessment. Results Nine studies involving 459 participants were included. There were no clinically significant changes for pain scores in SAA at 6-, 12-, 24-, and 48-hour postoperative timepoints. Patients receiving SAA used less morphine equivalents of pain medication at 12 hours only (−0.37 mg, 95% confidence interval: −0.63 to −0.11), but there was no significant difference at 24 and 48 hours. There were no major complications (infection or reoperation). Included trials demonstrated a moderate risk-of-bias, and low to very low quality of evidence for primary outcomes. Conclusion Subacromial continuous infusion of local anesthetic does not provide a clinically significant benefit compared with placebo as part of a multimodal analgesia regime after arthroscopic subacromial surgical procedures. Future, high-quality trials are required to further assess the efficacy of SAA against placebo.

The purpose of this investigation was to characterize the scapular position and scapular muscle activation during the empty can (EC) and full can (FC) exercises. The EC exercise has been shown to produce scapular kinematics associated with the mechanism leading to subacromial impingement syndrome (SAIS) but has not been investigated in patients with (SAIS). This investigation will help improve the treatment of patients with SAIS.Participants with SAIS (n = 28) performed 5 consecutive repetitions of FC and EC exercises. Scapular and clavicular 3-dimensional positions and scapular muscle activity were measured during each exercise. Pain was measured with the numeric pain rating 11-point scale.Participants reported greater pain during the EC exercise vs the FC exercise (difference, 1; P = .003). During the EC exercise, participants were in greater scapular upward rotation (difference, 3°; P .001), internal rotation (mean difference, 2°; P = .017), and clavicular elevation (difference, 3°, P .001) and in less scapular posterior tilt (difference, 2°; P .001). There was greater activity of upper trapezius (difference, 4%, P = .002), middle trapezius (difference, 3%; P .001), and serratus anterior (difference, 0.5%; P = .035) during ascent, and during the descent of greater upper trapezius (difference, 2%, P = .005), and middle trapezius (difference, 1%; P = .003), but less activity of the lower trapezius (difference, 1%; P = .039).The EC exercise was associated with more pain and scapular positions that have been reported to decrease the subacromial space. Scapular muscle activity was generally higher with the EC, which may be an attempt to control the impingement-related scapular motion. The FC exercise of elevation is preferred over the EC exercise.

Subacromial impingement is a common cause of shoulder pain and one cause of rotator cuff disease. We aimed to identify which shoulder motions cause subacromial impingement by measuring the vertical displacement and peak strain of the coracoacromial ligament using ultrasound speckle tracking imaging.Sixteen shoulders without shoulder disability were enrolled. All subjects were men, and the average age was 28.6 years. The vertical displacement and peak strain of the coracoacromial ligament were analyzed by the motion tracing program during the following active assisted motions (active motion controlled by the examiner): (1) forward flexion in the scapular plane, (2) horizontal abduction in the axial plane, (3) external rotation with the arm at 0° abduction (ER0), (4) internal rotation with the arm at 0° abduction (IR0), (5) internal rotation with the arm at 90° abduction (IR90), and (6) internal rotation at the back (IRB).The mean vertical displacement of the coracoacromial ligament during forward flexion (2.2 mm), horizontal abduction (2.2 mm), and IR90 (2.4 mm) was significantly greater than that during the other motions (ER0, -0.7 mm; IR0, 0.5 mm; IRB, 1.0 mm; P.003). The mean peak strain was significantly higher in forward flexion (6.88%), horizontal abduction (6.58%), and IR90 (4.88%) than with the other motions (ER0, 1.42%; IR0, 1.78%; IRB, 2.61%; P.003).Forward flexion, horizontal abduction, and IR90 showed higher vertical displacement and peak strain of the coracoacromial ligament, causing subacromial impingement. It is recommended that patients with impingement syndrome or a repaired rotator cuff avoid these shoulder motions.

Background We evaluated the factors that affect the natural course of subacromial impingement syndrome in patients without rotator cuff tears. Methods In total, 63 patients were included. During the first evaluation, we recorded each patient’s age, gender, profession, body mass index (BMI), hand dominance, alcohol and tobacco consumption, comorbidities, causative event of pain, presence of a functional limitation, duration of symptoms, shoulder scores (American Shoulder and Elbow Surgeons [ASES], Constant-Murley, and visual analog scale), history of subacromial steroid injections, and magnetic resonance imaging (MRI) classification. A subacromial lidocaine injection test was performed to confirm the diagnosis, and patients were initially treated conservatively. Of the 63 patients, 7 underwent a subsequent surgical procedure. We recalled the patients and questioned them about recurrences. According to their answers, the patients were grouped as follows: group 1, no recurrence; group 2, relapsing course; and group 3, chronic course. We compared the groups regarding the factors proposed to affect the course of the disease. Results The mean follow-up time was 8.45 ± 0.9 years. There were no significant differences regarding gender, profession, hand dominance, alcohol consumption, smoking, comorbidities, causative event of pain, visual analog scale score, or history of subacromial steroid injections between groups. The patients in group 1 were significantly younger than those in group 2 ( P = .038). The mean BMI value of the group 1 patients was significantly lower than that of the group 3 patients ( P = .034). Patients with a functional limitation besides pain tended to have a relapsing course. The Constant-Murley and ASES scores were significantly higher for patients in group 1 than for patients in group 2 ( P = .024 and P = .041, respectively). The duration of symptoms was significantly shorter ( P = .001). Most of the patients in group 1 had reversible changes on MRI ( P = .038). Conclusion In our study, younger age, lower BMI, more functional capacity, a shorter symptomatic period, reversible changes on MRI, and higher Constant and ASES scores at the first evaluation were good prognostic factors.

Background: Nocturnal shoulder pain resulting in poor sleep quality is a common finding in patients with shoulder disease. The purpose of this paper was to describe and to compare the sleep quality, pain, and function in adult subjects who have been diagnosed with rotator cuff disorders, osteoarthritis, or adhesive capsulitis (AC). Methods: Patients completed a clinical assessment and comprehensive questionnaire regarding their current medical health history, shoulder symptoms, and impact of their symptoms on activities of daily living and quality of sleep. Results: The study analyzed 343 patients with an average age of 57.4 years. The mean Single Assessment Numeric Evaluation score for AC was 34%, which was significantly lower than the score for the subacromial impingement syndrome group of 53% (P ¼.007). The mean American Shoulder and Elbow Surgeons scale score for AC was 38, which was also significantly lower than the score for the subacromial impingement syndrome group of 51 (P ¼ .007). There were no significant differences in pain, with mean scores ranging from 4.90 to 5.82 for diagnostic subgroups on a visual analog scale (P ¼ .28). Sleep quality was significantly poorer in the AC group (P ¼ .008), with a mean Pittsburgh Sleep Quality Index score of 12.07. Specific subcomponents of the Pittsburgh Sleep Quality Index that had a significant impact on sleep interruption included sleep quality, sleep duration, and habitual sleep efficiency in the AC group (P < .05). Conclusion: This study shows that whereas many patients with shoulder disease may have sleep-related issues, patients with adhesive capsulitis are particularly vulnerable to reduced sleep quality. Level of evidence: Level III, Cross-Sectional Design, Epidemiology Study. 2015 Journal of Shoulder and Elbow Surgery Board of Trustees.

Background Little is known about the incidence and characteristics of primary, or external, shoulder impingement in an occupationally and physically active population. A longitudinal, prospective epidemiologic database was used to determine the incidence and risk factors for shoulder subacromial impingement in the United States (U.S.) military. Our hypothesis was that shoulder impingement is influenced by age, sex, race, military rank, and branch of service. Methods The Defense Medical Epidemiology Database was queried for all shoulder impingement injuries using International Classification of Disease, Ninth Addition, Clinical Modification code 726.10 within a 10-year period from 1999 through 2008. An overall injury incidence was calculated, and a multivariate analysis performed among demographic groups. Results In an at-risk population of 13,768,534 person-years, we identified 106,940 cases of shoulder impingement resulting in an incidence of 7.77/1000 person-years in the U.S. military. The incidence of shoulder impingement increased with age and was highest in the group aged ≥40 years (incidence rate ratio [IRR], 4.90; 95% confidence interval [CI], 4.61-5.21), was 9.5% higher among men (IRR, 1.10, 95% CI, 1.06-1.13), and compared with service members in the Navy, those in the Air Force, Army, and Marine Corps were associated with higher rates of shoulder impingement (IRR, 1.46 [95% CI, 1.42-1.50], 1.42 [95% CI, 1.39-1.46], and 1.31 [95% CI, 1.26-1.36], respectively). Conclusions The incidence of shoulder impingement among U.S. military personnel is 7.77/1000 person-years. An age of ≥40 years was a significant independent risk factor for injury.

Background The purpose of this study is to analyze the 3-dimensional scapular dyskinesis and the kinematics of a hook plate relative to the acromion after hook-plated acromioclavicular dislocation in vivo. Reported complications of acromioclavicular reduction using a hook plate include subacromial erosion and impingement. However, there are few reports of the 3-dimensional kinematics of the hook and scapula after the aforementioned surgical procedure. Methods We studied 15 cases of acromioclavicular dislocation treated with a hook plate and 15 contralateral normal shoulders using computed tomography in the neutral and full forward flexion positions. Three-dimensional motion of the scapula relative to the thorax during arm elevation was analyzed using a computer simulation program. We also measured the distance from the tip of the hook plate to the greater tuberosity, as well as the angular motion of the plate tip in the subacromial space. Results Decreased posterior tilting (22° ± 10° vs 31° ± 8°) in the sagittal plane and increased external rotation (19° ± 9° vs 7° ± 5°) in the axial plane were evident in the affected shoulders. The mean values of translation of the hook plate and angular motion against the acromion were 4.0 ± 1.6 mm and 15° ± 8°, respectively. The minimum value of the distance from the hook plate to the humeral head tuberosity was 6.9 mm during arm elevation. Conclusions Acromioclavicular reduction using a hook plate may cause scapular dyskinesis. Translational and angular motion of the hook plate against the acromion could lead to subacromial erosion. However, the hook does not seem to impinge directly on the humeral head.

Internal impingement and decreased anterior stability, which result from shoulder capsular loosening, are common shoulder pathologies in throwing athletes. The purpose of this study was to assess the effect of shoulder abduction angle on shoulder internal impingement and anterior shoulder stability during the simulated throwing motion.Eight cadaveric shoulders were tested by simulating the late-cocking and acceleration phases of the throwing motion for intact and thrower's shoulder conditions. The maximal glenohumeral external rotation, anterior translation, location of the rotator cuff insertion with respect to the glenoid, length and site of internal impingement, and glenohumeral contact pressure were measured. All data were compared between shoulder abduction angles of 80°, 90°, and 100°.Decreasing shoulder abduction in the simulated late-cocking phase shifted the humeral head posteriorly (P .03) and superiorly (P .001), decreasing the total internal impingement area between the greater tuberosity and glenoid (P = .04) and increasing the glenohumeral contact pressure during internal impingement (P = .02). In the simulated acceleration phase, anterior glenohumeral translation significantly increased as the shoulder abduction angle decreased (P .001).Decreasing shoulder abduction significantly increased the contact pressure during internal impingement in the simulated late-cocking phase of the throwing motion. During the simulated acceleration phase of the throwing motion, anterior glenohumeral translation significantly increased as shoulder abduction decreased.

Background Our study purpose was to determine the optimal glenoid and humeral reverse shoulder arthroplasty (RSA) component design and position in osteoarthritic shoulders with severe glenoid retroversion deformities. Methods Computed tomography scans from 10 subjects were analyzed with advanced software including RSA range of motion (ROM) analysis. Variables included glenoid component retroversion of 0°, 5°, 10°, 15°, and 20° and baseplate lateralization of 0, 5, and 10 mm. Humeral variables included 135°, 145°, and 155° angle of inclination (AOI) combined with variable humeral offset. Results Glenoid component lateralization had the greatest influence on ROM. In comparing each ROM direction among all lateralization options independently, there were significantly greater adduction, abduction, external rotation, extension, and flexion motions with progressively greater lateralization. Internal rotation motion was greater at 10 mm only. In analyzing the effects of glenoid version independently, no differences in adduction or abduction ROM were seen. With greater retroversion, decreased external rotation and extension motion was noted; however, greater internal rotation and flexion motion was seen with the exception of flexion at 10 mm of lateralization. For adduction, external rotation, and extension, a more valgus AOI resulted in less ROM at each progressively greater AOI independent of humeral lateralization. Internal rotation and flexion motions were greater with a more varus AOI but not significant between each inclination angle. Abduction ROM was maximized with a more valgus AOI. Humeral lateralization had no effect on ROM. Conclusions In the setting of RSA for advanced glenoid osteoarthritic deformities, optimal ROM is achieved with 10-mm baseplate lateralization and neutral to 5° of retroversion mated to a humeral implant with a varus (135°) inclination angle.

Background Medialization of the glenohumeral center of rotation alters the moment arm of the deltoid, can affect muscle function, and increases the risk for scapular notching due to impingement. The objective of this study was to determine the effect of position of the glenosphere on deltoid efficiency and the range of glenohumeral adduction. Methods Scapulohumeral bone models were reconstructed from computed tomography scans and virtually implanted with primary or reverse total shoulder arthroplasty implants. The placement of the glenosphere was varied to simulate differing degrees of “medialization” and inferior placement relative to the glenoid. Muscle and joint forces were computed during shoulder abduction in OpenSim musculoskeletal modeling software. Results The average glenohumeral joint reaction forces for the primary total shoulder arthroplasty were within 5% of those previously reported in vivo. Superior placement or full lateralization of the glenosphere increased glenohumeral joint reaction forces by 10% and 18%, respectively, relative to the recommended reverse total shoulder arthroplasty position. The moment arm of the deltoid muscle was the highest at the recommended baseline surgical position. The baseline glenosphere position resulted in a glenohumeral adduction deficit averaging more than 10° that increased to more than 25° when the glenosphere was placed superiorly. Only with full lateralization was glenohumeral adduction unaffected by superoinferior placement. Discussion/Conclusion Selecting optimum placement of the glenosphere involves tradeoffs in bending moment at the implant-bone interface, risk for impingement, and deltoid efficiency. A viable option is partially medializing the glenosphere, which retains most of the benefits of deltoid efficiency and reduces the risk for scapular notching.

Background Shoulder impingement syndrome is the most common shoulder disorder. Even though conservative treatment is the primary treatment of choice, surgery has increased substantially in several countries during the last 20 years. This has resulted in recommended clinical guidelines for treatment of shoulder impingement syndrome in countries such as The Netherlands and Denmark during recent years. The aim of this study was to investigate the effectiveness of an arthroscopic subacromial decompression in 244 patients selected for surgery according to national clinical guidelines. Materials and Methods Patients were included from an Internet-based shoulder and elbow database. They were asked to complete 2 questionnaires consisting of the Oxford Shoulder Score (OSS) and the EuroQol 5-Dimension 3-Level and visual analog scale preoperatively and at 6-month follow-up. All patients were carefully selected for surgery according to the national guidelines, with symptoms persisting for at least 6 months. Furthermore, subgroups related to the OSS were formed to assess the clinical outcome according to preoperative status and age. Results For the complete study group, an OSS change of 10 (8.8-11.2; P = .0001) was found at 6-month follow-up. No significant difference was found between the genders ( P = .17). The largest clinical effect from the intervention was found in the low preoperative OSS (pre-OSS) group, in which a mean change of 17 was found. The moderate and high pre-OSS groups had mean changes of 13 and 5, respectively. Similarly, according to the EuroQol 5-Dimension 3-Level and visual analog scale, the largest improvements were seen in the low and moderate pre-OSS groups. Conclusion Arthroscopic subacromial decompression is a valid treatment, reducing pain and improving quality of life for patients selected for surgery according to the Danish national guidelines.

Background To determine whether radiofrequency based plasma microtenotomy has a positive effective in the treatment of shoulder impingement syndrome with cuff tendinosis. Materials and methods Eighty patients with impingement syndrome and cuff tendinosis that were treated arthroscopically were enrolled in the study. The patients were randomly assigned to receive either arthroscopic subacromial decompression (ASD) alone (ASD group, n=40) or arthroscopic subacromial decompression combined with radiofrequency (RF) based plasma microtenotomy (RF group, n=40). Clinical outcome data including VAS pain score, shoulder range of motion (ROM), ASES, UCLA, Constant-Murley, and SST score were recorded preoperatively and at 3 weeks, 6 weeks, 3 months, 6 months, and 1 year postoperatively. Results Sixty-five out of eighty patients (81.3%) were available for the final follow-up at 1 year postoperation. There were 32 patients in the ASD group and 33 in the RF group. Both treatment groups showed significantly ( P = .031 in the ASD group vs P = .017 in the RF group) reduced pain 3 weeks postoperatively. Both treatment groups showed significantly improved functional scores 3 months postoperatively. Both treatment groups showed significantly improved flexion elevation (FE) and external rotation (ER) 1 year postoperatively and internal rotation (IR) 6 months postoperatively. No significant difference between the 2 groups was found in any of the outcome measurements at any time point postoperatively. Conclusion Arthroscopic subacromial decompression is a reliable treatment for refractory impingement syndrome. The additional radiofrequency based plasma microtenotomy did not show any significant positive effects regarding pain relief, ROM, or functional recovery.

Background Shoulder impingement syndrome is a common musculoskeletal complaint leading to reduced work ability. The aim of the present study was to identify predictors of long-term sick leave benefit and permanent benefits/permanently reduced work ability after arthroscopic subacromial decompression (ASD). Materials and methods The study included 615 individuals undergoing ASD (2003 to 2009). Data were linked to the 3 state registries concerning employment/benefits, medication, and industrial injuries. All individuals were monitored for 1 year, and 155 obtained complete 5-year follow-up. Risks were estimated in multivariate logistic regression models. Results At 1 year after ASD, 16.6% were receiving sick leave benefit. The reduced multiple logistic regression model (odds ratio [95% confidence interval]) included painkillers (2.18 [1.37-3.46]), strong painkillers/opioids (3.78 [2.32-6.16]), and age (0.97 [0.94-0.995]). At 5 years after ASD, 35 (22.6%) were receiving permanent benefit. Predictors (odds ratio [95% confidence interval] were transfer income 2 years before ASD (3.44 [1.20-9.86]), use of opioids at any time during a 1-year period after ASD (24.80 [7.05-87.18]), or other work claims not due to shoulder disease (5.99 [1.34-26.72]). Conclusion A high percentage were receiving sick leave benefit 1 year after ASD, and nearly a quarter were receiving a permanent benefit 5 years after ASD. Medication before ASD was not a predictor of outcome. The strongest predictor of long-term sick leave benefit and permanent benefit was opioid use during the first year after ASD. This may indicate that pain after surgery may be an issue that needs further attention.

Hypothesis: The nonanatomical design of reverse shoulder prostheses induce medial displacement of the center of rotation, impingements and may reduce the mobility of the shoulder. The aim of this study is to test the hypothesis that during activities of daily living functional mobility of the shoulder can be restored by scapular compensation. Material and methods: A numerical 3-dimensional model was developed to reproduce the movement of the scapula and humerus, during 4 activities of daily living measured experimentally. This hypothesis was tested in 4 configurations of the aequalis reverse prosthesis (standard 36-mm glenosphere, 42-mm glenosphere, lateralized 36-mm glenosphere, lateralized Bony Increased-Offset Reverse Shoulder Arthroplasty [BIO-RSA]), which were implanted in the virtual model. All impingement positions were evaluated, as the required scapular compensation to avoid impingements. Results: With the 36-mm glenosphere, impingements occurred only for rest of hand to back-pocket positions. The 42-mm partly improved the mobility. The 2 lateralized glenospheres were free of impingement. When impingements occurred, the scapular compensation was less than 10 degrees. Conclusion: Most reverse prostheses impingements reported in clinical and biomechanical studies can be avoided, either by scapular compensation or by a glenosphere lateralization. After reverse shoulder arthroplasty, a fraction of the mobility of the gleno-humeral is transferred to the scapulo-thoracic joint. Level of evidence: Basic Science Study, Computer Modeling. (C) 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.

Hypothesis The objective of this study was to compare the efficacy of subacromial injection of triamcinolone compared to injection of ketorolac in the treatment of external shoulder impingement syndrome. Methods Thirty-two patients diagnosed with external shoulder impingement syndrome were included in this double-blinded randomized controlled clinical trial. Each patient was randomized into the steroid group or nonsteroidal anti-inflammatory drugs (NSAID) group. The steroid syringe contained 40 mg triamcinolone; and the NSAID syringe contained 60 mg ketorolac. Each patient was evaluated in terms of arc of motion, visual analog scale (VAS) for evaluating pain, and the UCLA (The University of California at Los Angeles) shoulder rating scale. Results At 1 month follow-up, both treatment arms resulted in increased range of motion and decreased pain. The steroid group decreased in active abduction while the NSAID group increased (steroid: 134°, NSAID: 151°, P = .03). The mean improvement in the UCLA shoulder rating scale at 4 weeks was 7.15 for the NSAID group and 2.13 for the steroid group ( P = .03). Subgroup analysis of the UCLA scale demonstrated an increase in both forward flexion strength ( P = .04) and patient satisfaction ( P = .03) in the NSAID group. No significant difference could be seen in all other outcome measures. Conclusion In this study, an injection of ketorolac resulted in greater improvements in the UCLA shoulder rating scale than an injection of triamcinolone at 4 weeks follow-up. While both triamcinolone and ketorolac are effective in the treatment of isolated subacromial impingement, ketorolac appears to have equivalent if not superior efficacy; all the while decreasing patient exposure to the potential side-effects of corticosteroids.

Objective: Evidence for effective management of shoulder impingement is limited. The present study aimed to quantify the clinical, neurophysiological, and biomechanical effects of a scapular motor control retraining for young individuals with shoulder impingement signs.Method: Sixteen adults with shoulder impingement signs (mean age 22 ? 1.6 years) underwent the intervention and 16 healthy participants (24.8 ? 3.1years) provided reference data. Shoulder function and pain were assessed using the Shoulder Pain and Disability Index (SPADI) and other questionnaires. Electromyography (EMG) and 3 dimensional motion analysis was used to record muscle activation and kinematic data during arm elevation to 90? and lowering in 3 planes. Patients were assessed pre and post a 10-week motor control based intervention, utilizing scapular orientation retraining.Results: Pre-intervention, patients reported pain and reduced function compared to the healthy participants (SPADI in patients 20 ? 9.2; healthy 0 ? 0). Post intervention, the SPADI scores reduced significantly (P < .001) by a mean of 10 points (?4). EMG showed delayed onset and early termination of serratus anterior and lower trapezius muscle activity pre-intervention, which improved significantly post-intervention (P < .05). Pre intervention, patients exhibited on average 4.6-7.4? less posterior tilt, which was significantly lower in 2 arm elevation planes (P < .05) than healthy participants. Postintervention, upward rotation and posterior tilt increased significantly (P Conclusion: A 10-week motor control intervention for shoulder impingement increased function and reduced pain. Recovery mechanisms were indicated by changes in muscle recruitment andscapular kinematics. The efficacy of the intervention requires further examined in a randomizedcontrol trial.

Hypothesis and background Narrowing of the subacromial space has been implicated in several shoulder pathologies. However, the location of the minimum distance points during clinical testing has not been defined. We sought to measure the in vivo minimum distance and location of the minimum distance points on the acromion and proximal humerus during arm elevation. Methods Eight healthy male subjects (mean age, 30 years) underwent a dynamic in vivo biplane fluoroscopy assessment of scaption and forward elevation. For each frame, the 3-dimensional position and orientation of the humerus and scapula were determined, and the acromiohumeral distance (AHD) was measured as the shortest distance between the acromion and proximal humerus. Results The minimum AHD was 2.6 ± 0.8 mm during scaption and 1.8 ± 1.2 mm during forward flexion at elevation angles of 83° ± 13° and 97° ± 23°, respectively. The minimum distance point was located on the articular surface of the humeral head from the neutral arm position until 34° ± 8° for scaption and 36° ± 6° for forward flexion. Upon further elevation, the minimum distance point was located within the footprint of the supraspinatus muscle until 72° ± 12° for scaption and 65° ± 8° for forward flexion. At greater elevation angles, the minimum distance points were between the acromion and the proximal humeral shaft, distal from the greater tuberosity. Conclusions The shortest AHD was at approximately 90° of arm elevation. The AHD was no longer measured intra-articularly or within the supraspinatus footprint above approximately 70° of arm elevation.

Background Impingement after reverse shoulder arthroplasty (RSA) has been correlated with implant design and surgical techniques. Previous studies suggested that humeral retroversion can reduce impingement and increase external rotation range of motion (ROM). The purpose of this study was to determine how humeral version affects impingement in activities of daily living (ADLs). Materials and methods A single surgeon performed virtual RSA on 30 arthritic shoulders that were reconstructed from preoperative computed tomography scans. For each subject, the humeral component was placed into 5 versions: −40°,−20°, 0°, +20°, and +40° (– indicates retroversion, + indicates anteversion). Intra-articular and extra-articular impingement was calculated for 10 ADLs. Impingement-free ROM was also calculated for abduction, forward flexion, scapula plane elevation, and internal/external rotation (standardized tests). Risk of impingement for ADLs was assessed as the collective duration and frequency of impingement across all motions. Frequent impingement sites were identified. Results For the ADLs, 0° version showed the least amount of impingement. In contrast, 40° retroversion resulted in the largest ROM for the standardized tests (118° ± 19° abduction, 109° ± 16° forward flexion, 111° ± 10° scapula plane elevation, 140° ± 15° internal/external rotation). The site of impingement changed with version: retroversion increased the extra-articular impingement, and anteversion increased the contact between the inferior glenoid and the humeral cup. Conclusions Humeral version can significantly affect impingement in RSA. Maximizing ROM in standardized tests may not reduce the risk of impingement during ADLs. Our results showed that an average 0° of version should be preferred, but the large variability among subjects suggested that optimum version may vary among individuals.

Purpose We evaluated the feasibility of contralateral trapezius transfer to restore shoulder external rotation. Materials and methods The length of the lower trapezius and distance necessary for contralateral trapezius transfer were measured in 20 volunteers and directly in 12 cadavers. The average distances between the medial spine of the scapula and T12 (length of lower trapezius) and the spine to the greater tuberosity (distance for transfer) were measured with the scapula neutral, maximally protracted, and maximally retracted. In cadavers, the origin of the lower trapezius was detached, transferred to the contralateral greater tuberosity, and retracted to determine its effectiveness in external rotation and tension on the vascular pedicle. Results In volunteers, the average difference between the length of the lower trapezius and the transfer distance was 19 mm in neutral. When the scapula was protracted and retracted, the difference was 79 and −49 mm. In the cadavers, the average transfer distance (in mm) was 290 ± 12, 365 ± 15, and 209 ± 25 in the neutral, protracted, and retracted positions, respectively. The average length of the lower trapezius (in mm) was 270 ± 10, 285 ± 12, and 258 ± 10 in the neutral, protracted, and retracted positions. The transfer was universally feasible when the scapula was partially retracted. Prolongation of the lower trapezius with lumbar fascia made the transfer possible in all scapular positions. Pulling on the transferred muscle resulted in contralateral shoulder external rotation without tension or impingement on the neurovascular pedicle. Conclusion Contralateral trapezius transfer to the infraspinatus insertion appears feasible and potentially effective in restoration of shoulder external rotation.

Background Scapular dyskinesis is an abnormal scapular motion or position during active arm elevation. Dyskinesis is theorized to contribute to impingement syndrome by decreasing the subacromial space. A corrective maneuver of the scapular assistance test (SAT) proposes to increase scapular upward rotation and posterior tilt to increase the subacromial space. The purpose of this study is to determine the influence that 1) scapular dyskinesis and 2) passive manual correction with the SAT have on subacromial space and 3-dimensional (3-D) scapular kinematics. Materials and methods Forty asymptomatic participants were classified with either obvious dyskinesis (n = 20) or normal motion (n = 20) using the scapular dyskinesis test. The anterior outlet of the subacromial space was measured via the acromiohumeral distance using ultrasound imaging and 3-D scapular orientation was assessed with electromagnetic motion analysis, with the arm at rest 45° and 90° of active elevation with and without the SAT, respectively. Results There were no differences in acromiohumeral distance or scapular kinematics with static active arm elevation between groups. The SAT increased scapular upward rotation, posterior tilt, and acromiohumeral distance in both groups. Participants with dyskinesis demonstrated greater scapular mobility in upward rotation with the SAT, but no additional increase in acromiohumeral distance. Conclusion Scapular dyskinesis identified during active motion did not result in different 3-D scapular orientation or acromiohumeral distance during active arm elevation in static positions; however, the SAT altered scapular kinematics and increased acromiohumeral distance. The SAT may be helpful to identify individuals where subacromial compression is producing symptoms, regardless of dyskinesis.

Subacromial impingement is common and frequently treated with arthroscopic subacromial decompression (ASD); however, its efficacy has recently been questioned. Poor surgical outcomes have been associated with anxiety and depression within other orthopedic subspecialties but not within this group of patients. We hypothesized that anxiety and depression are associated with worse outcomes after ASD.A retrospective review of prospectively collected data was carried out of patients undergoing ASD. Inclusion criteria were short-term relief with injection therapy and presence of Hawkins sign. Rotator cuff tears were excluded. Patients completed the Oxford Shoulder Score (OSS), Hospital Anxiety and Depression Scale (HADS), and visual analog scale for pain before and after surgery in outpatient clinic follow-up at 6 weeks and by postal questionnaire at 6 months.The 86 patients who participated in the study were analyzed in 2 groups defined by HADS scores, group A being depressed and group B nondepressed. Both groups had less pain and improved OSS at 6 months; however, group B improved faster with improved scores at 6 weeks, which were maintained to 6 months. Group B had less pain and higher OSS at 6 months than group A. There was strong negative correlation (P .01) between preoperative HADS score and 6-week and 6-month OSS and HADS scores. There was strong positive correlation (P .01) between HADS score and 6-week and 6-month pain scores. High preoperative HADS score was negatively correlated to 6-month satisfaction (P .05).Patients with HADS score11 before ASD have worse outcomes. This should be taken into account when counseling patients for surgery.

Background Coordinated muscle activity is needed for synchronized joint motion and stability. Characterizing relative scapular muscle activity deficits in participants with shoulder pain will provide foundational knowledge to develop rehabilitation programs. Methods Participants were recruited with subacromial pain syndrome and an asymptomatic control group matched for age, gender, and dominant arm (N = 56). Surface electromyographic muscle activity was recorded from the upper, middle, and lower trapezius (UT, MT, LT) and serratus anterior (SA) during 5 repetitions of a weighted arm elevation task. Muscle activity was normalized to a reference contraction and then expressed as UT/MT, UT/LT, UT/SA, and LT/SA ratios. Ratios were compared between groups and across 3 arm angle intervals during ascending and descending elevation. Results A 2 × 3 mixed-model analysis of variance yielded a group main effect for the UT/LT ratio, with a higher ratio in the subacromial pain group during ascending (mean difference, 0.92; P = .008) and descending (mean difference, 0.70; P = .030). For the LT/SA ratio, there was a group effect: a lower ratio in the subacromial group during ascending (mean difference, −0.25; P = .026) and descending (mean difference, −0.51; P = .032). There were no differences for the UT/MT or UT/SA. Discussion There is a disruption in coordination between the LT and SA and the UT and LT during an arm elevation task in patients with subacromial pain syndrome. The LT was part of both altered ratios, indicating the relative importance of the LT. Future research should determine if exercises aimed at restoring the dysfunctional LT/SA and UT/LT force couples are beneficial to reduce shoulder pain and disability in patients with unilateral shoulder pain.

Background The mechanisms underlying symptom development in rotator cuff tears are still unknown. The purpose of this study was to identify the characteristics associated with symptoms of rotator cuff tears. Materials and methods We performed a medical checkup on residents of a mountain village. The subjects of this study included 211 individuals with 283 shoulders in which a full-thickness rotator cuff tear was observed through ultrasonography. We recorded the subjects' background and medical history and then performed physical examinations. The subjects were divided into 2 groups according to whether they had any pain or disabilities that they felt subjectively while performing their usual daily activities. We determined the prevalence of an asymptomatic rotator cuff tear and conducted a statistical analysis to compare any differences between the 2 groups. Results Of the 283 subjects, 65.4% with rotator cuff tears had no symptoms involving the shoulder. Asymptomatic rotator cuff tears were associated with a tear in the nondominant arm, a negative impingement sign, higher active forward elevation, and intact muscle strength in abduction and external rotation. A logistic regression analysis showed that a positive impingement sign, weakness in external rotation, and presence of a tear in the dominant arm were significantly associated with the presence of symptoms of rotator cuff tears. Conclusions In the general population, in approximately two-thirds of all rotator cuff tears, there are no symptoms, and the factors involved in the presence of symptoms associated with rotator cuff tears were identified to be a positive impingement sign, weakness in external rotation, and presence of a tear in the dominant arm.

Hypothesis A recent ultrasound study has shown that impingement phenomenon was observed in healthy shoulders. We hypothesized that nonpathologic contact beneath the coracoacromial arch occurs in normal shoulders. Materials and methods Seven fresh-frozen cadaveric shoulders were studied. Each specimen was attached to a custom-designed shoulder-positioning device. A 22-N force was applied to the humeral head to keep it centered in the glenoid fossa. Contact pressure beneath the coracoacromial arch was measured by a flexible force sensor during flexion, abduction, internal and external rotation, extension, and horizontal abduction motions. Bending deformation of the coracoacromial ligament was measured by a linear variable differential transducer sensor. Data were recorded with the arm from 0° to maximum range of motion with 10° increments. Results Contact pressure with the coracoacromial ligament and acromion was not zero in the neutral position and increased during particular motions, such as flexion, abduction, horizontal abduction, and extension, whereas it was almost constant during internal and external rotation. Bending deformation of the coracoacromial ligament during flexion, abduction, and horizontal abduction motions was also shown to be greater than that during internal and external rotation. Discussion It is possible that repetitive contact of the coracoacromial ligament may cause degenerative changes, and a ridge of proliferative acromial spurs may be the result of nonpathologic contact. Conclusions Contact phenomenon of the coracoacromial arch was observed during all motions. Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders.

A successful clinical result is reported in 75% to 85% of impingement patients after arthroscopic subacromial decompression. The result is maintained over time, but few studies have investigated the integrity of the rotator cuff in these patients.Using ultrasonography, we examined the integrity of the rotator cuff in 70 patients 15 years after arthroscopic subacromial decompression. All patients had an intact rotator cuff at the index procedure.Tendons were still intact in 57 patients (82%), 10 (14%) had partial-thickness tears, and 3 (4%) had full-thickness tears.The total number of 18% tears (partial and full thickness) in this study, including patients clinically diagnosed with subacromial impingement at a mean age of 60 years, is unexpectedly low compared with 40% degenerative tears reported in asymptomatic adults of the same age.Arthroscopic subacromial decompression seems to reduce the prevalence of rotator cuff tears in impingement patients. This appears attributable to elimination of extrinsic factors such as mechanical wear and bursitis. The potential effect of surgery on intrinsic cuff degeneration is unknown, but intrinsic factors may explain tears still developing despite decompression.Level III, therapeutic study.

Background Although prior researchers have assessed glenohumeral arthrokinematics using isometrically held arm postures with standard radiographs, dynamic assessment of glenohumeral arthrokinematics has been limited. This study utilized video fluoroscopy to analyze superior inferior glenohumeral migration during dynamic arm elevation in individuals with outlet impingement syndrome, before and after fatigue of the rotator cuff. Hypothesis Prior to the study, it was hypothesized that during the pre-fatigue state, glenohumeral migration would be in the superior direction, and that post-fatigue there would be a significant increase in superior migration. Materials and methods Digital fluoroscopic videos (30 Hz) were used to analyze 20 male volunteers (27.7 ± 7.3 years) with right shoulder outlet impingement syndrome during concentric elevation of the arm in the plane of the scapula, both before and after fatigue of the rotator cuff. Results During concentric arm elevation, there was superior glenohumeral migration (1.6 mm) between 45° and 90° of arm elevation, regardless of fatigue-state ( P = .02). After rotator cuff fatigue, the humeral head was positioned more superiorly on the glenoid fossa ( P = .03). The position of the humeral head was 0.4 mm more superior than that reported in a previous study on healthy individuals. Conclusion These results support prior findings that suggest superior glenohumeral migration during arm elevation is influenced both by shoulder pathology and the state of fatigue of the rotator cuff musculature. Future research should examine the effects of physical therapy and surgical interventions on glenohumeral arthrokinematics to better determine the most effective treatment methods for outlet impingement. Level of evidence Controlled laboratory study

Background Reverse total shoulder arthroplasty is a treatment option for cuff tear arthropathy. Scapular notching remains a concern. This biomechanical study compared the range-of-motion in different designs of glenospheres and hence the relative risk of scapular notching. Method A precision coordinate device was used to investigate four different designs of glenospheres (SMR prosthesis); 36mm concentric (Standard), 36 mm eccentric, 44 mm concentric, and 44 mm eccentric glenospheres. The centre of rotation in each design was first established. The position of the humeral prosthesis was recorded in the plane of the scapula to compare the degree of adduction and the total range-of-motion. Results Eccentric glenospheres were found to improve range-of-motion by allowing a higher degree of adduction. Larger diameter glenospheres were found to improve range-of-motion by increasing adduction and abduction. Compared to the 36 mm concentric (standard) glenosphere, the 36 mm eccentric glenosphere improved adduction by 14.5 degrees, the 44 mm concentric glenosphere improved adduction by 11.6 degrees, the 44 mm eccentric glenosphere improved adduction by 17.7 degrees. Conclusion Eccentric glenospheres with a center-of-rotation placed more inferiorly were shown to improve adduction. This design may reduce the clinical incidence of scapular notching. Level of evidence Basic science study.

Hypothesis We prospectively studied patients with impingement syndrome to look at outcomes of nonoperative treatment on a temporal basis. Materials and methods Temporal outcomes of 100 consecutive patients treated for impingement syndrome were prospectively evaluated. All patients began a standardized, nonoperative treatment protocol consisting of a subacromial steroid injection, followed by physical therapy. Results Data were available on 94 patients at the final two-year follow-up assessment. Overall, 74 of 94 patients did not require surgery. In that group, the average American Shoulder and Elbow Surgeons (ASES) outcome score increased from 56 to 95, with an average decrease in the pain score from 4.8 to 0.6. Improvement was demonstrated in patient shoulder outcome scores (ASES score) and visual analog pain scores between treatment initiation and the one-year follow-up assessment ( p .0001); no improvement was identified past one year. Of the non-surgical patients, 22 continued to have some shoulder pain. Conclusion Of patients with impingement syndrome treated nonoperatively, 79% did not require surgery after two-year follow-up. Predictors of patients going on to surgical intervention included the total number of subacromial steroid/lidocaine injections and patient response to the initial subacromial injection. Of the patients not undergoing surgery, 30% continued to have some shoulder pain. Level of evidence Level 1; Prospective prognosis study, >80% follow-up.

We dissected 80 shoulders from 44 fresh cadavers to define variants of the coracoacromial ligament and their relationship to rotator cuff degeneration. The shapes and the geometric data of the ligaments were investigated, and the rotator cuffs of the cadavers were evaluated macroscopically. Five main types of coracoacromial ligaments were found: Y-shaped, broad band, quadrangular, V-shaped, and multiple-banded. The Y-shaped ligament was the most frequent type, with a frequency of 41.3%, and the V-shaped ligament (11.2%) has not been previously reported. Of the cadavers that were dissected bilaterally, 64% showed the same type of ligament. There was no statistical significance between rotator cuff degeneration and the type or geometric measurement of the ligament. However, the coracoacromial ligaments with more than 1 bundle showed significant association with rotator cuff degeneration with a longer lateral border and larger coracoid insertion.