SS-31 as a Mitochondrial Protectant in the Treatment of Tendinopathy: Evaluation in a Murine Supraspinatus Tendinopathy Model.

BACKGROUND: Prior studies have demonstrated mitochondrial dysfunction in tendinopathy. The objective of this investigation was to explore the potential of SS-31 (elamipretide), a mitochondrial protectant, to improve mitochondrial function and promote tendon healing in a murine supraspinatus tendinopathy model. METHODS: One hundred and twenty-six mice (252 limbs) were divided into 6 groups (42 limbs/group) that received (I) 4 weeks of impingement; (II) 8 weeks of impingement; (III) 8 weeks of impingement including 4 weeks of SS-31 treatment (5 mg/kg/d) starting after 4 weeks of impingement; (IV) 4 weeks of impingement ending with clip removal, followed by harvesting 4 weeks later; and (V) 4 weeks of impingement ending with clip removal, followed by 4 weeks of SS-31 treatment and harvesting; and a control group. Specimens were prepared for biomechanical testing, histological analysis, transmission electron microscopy, measurement of superoxidative dismutase (SOD) activity, and measurement of gene expression. RESULTS: Failure force decreased after impingement, compared with the intact tendon, and the decrease was partially reversed after clip removal, SS-31 treatment, and the 2 treatments combined. A similar pattern was observed for stiffness. Histological analysis demonstrated higher modified Bonar scores in the impingement groups; however, the changes in tendon morphology were partially reversed following all treatments, especially the combined treatment. Decreased mitochondrial number and altered organization and density of cristae were observed in the impingement groups. Mitochondrial structure and number became more normal, with improvement in morphology of the cristae, after clip removal and/or SS-31 treatment. SOD activity decreased after impingement, compared with the control group, then increased significantly again after treatment, especially in the combined treatment group. Mitochondria-related gene expression decreased in the impingement groups and increased again after treatment. CONCLUSIONS: The mitochondrial protectant SS-31 improved mitochondrial function, promoting tendon healing, especially when combined with removal of subacromial impingement. CLINICAL RELEVANCE: Improving mitochondrial function with agents such as SS-31 may represent an effective treatment to promote healing in the setting of supraspinatus tendinopathy.

Assessment of Mitochondrial Dysfunction in a Murine Model of Supraspinatus Tendinopathy.

BACKGROUND: The purpose of this study was to assess mitochondrial dysfunction in a murine model of supraspinatus tendinopathy. METHODS: Eighty-four mice (168 limbs) were included in the study. Supraspinatus tendinopathy was induced by inserting a microsurgical clip in the subacromial space of 63 mice bilaterally (126 limbs). Forty-two of these limbs were harvested at 4 weeks postoperatively, 42 underwent clip removal at 4 weeks after the initial procedure and were harvested at 2 weeks, and 42 underwent clip removal at 4 weeks and were harvested at 4 weeks. Forty-two limbs in the remaining 21 mice did not undergo surgical intervention and were utilized as the control group. Outcomes included biomechanical, histological, gene expression, superoxide dismutase (SOD) activity, and transmission electron microscopy (TEM) analyses. RESULTS: Radiographs confirmed stable clip position in the subacromial space at 4 weeks. Biomechanical testing demonstrated a 60% decrease in failure force of the supraspinatus tendons at 4 weeks compared with the control group. The failure force gradually increased at 2 and 4 weeks after clip removal. Histological analysis demonstrated inflammation surrounding the tendon with higher modified Bonar scores at 4 weeks after clip placement followed by gradual improvement following clip removal. The expression of mitochondrial-related genes was decreased at 4 weeks after clip placement and then significantly increased after clip removal. SOD activity decreased significantly at 4 weeks after clip placement but increased following clip removal. TEM images demonstrated alterations in morphology and the number of mitochondria and cristae at 4 weeks after clip placement with improvement after clip removal. CONCLUSIONS: Mitochondrial dysfunction appears to be associated with the development of tendinopathy. CLINICAL RELEVANCE: Mitochondrial protection may offer a potential strategy for delaying the development of tendinopathy and promoting tendon healing.

Increased levels of inflammatory markers in the subscapularis tendon and joint capsule in patients with subacromial impingement.

PURPOSE: To analyze biopsy samples from the subscapularis tendon and from the joint capsule from male patients with subacromial impingement syndrome and compare them with samples from male patients with post-traumatic recurrent shoulder instability, to detect increased inflammatory activity that might be present inside the humeroscapular joint. METHODS: Twenty male patients scheduled for surgery for either subacromial decompression or Bankart reconstruction were included. Four biopsies from each patient were obtained during surgery from the capsule and the subscapularis tendon. Each specimen was analyzed for TNF-α, IL-6, CD-3 and CD-72. Multiplex fluorescence immunohistochemistry was performed on histological samples from the capsule and tendon to demonstrate the level of inflammatory markers. Fluorescence microscope images were acquired using an automated scanning system. On each slide, the number of pixels was registered and used in the analyses. RESULTS: The subacromial impingement syndrome group comprised eight patients, median age 53 (45-74) years, while the instability group 12, median age 27 (22-48) years (p < 0.00001). The amount of IL-6 and TNF-α was significantly higher in the subscapularis tendon of the patients with subacromial impingement syndrome compared with instability patients (p = 0.0015 and p = 0.0008 respectively). In the capsular samples, significantly higher amount of TNF-α and CD-72 was found in patients with subacromial impingement syndrome compared with instability patients (p < 0.0001 for both). On the other hand, the amount of CD-3 was significantly higher in the instability group (p = 0.0013). CONCLUSIONS: This study provides evidence that an extended inflammatory process is present, not only in the subacromial bursa but also in the glenohumeral joint in patients with subacromial impingement syndrome. LEVEL OF EVIDENCE: Level III. CLINICAL RELEVANCE: To develop a treatment targeted towards intra-articular inflammatory cytokines appears appealing.

Evaluating the role of subacromial impingement in rotator cuff tendinopathy: Development and analysis of a novel murine model.

Subacromial impingement of the rotator cuff is understood as a contributing factor in the development of rotator cuff tendinopathy. However, changes that occur in the impinged tendon are poorly understood and warrant further study. To enable further study of rotator cuff tendinopathy, we performed a controlled laboratory study to determine feasibility and baseline characteristics of a new murine model for subacromial impingement. This model involves surgically inserting a microvascular clip into the subacromial space in adult C57Bl/6 mice. Along with a sham surgery arm, 90 study animals were distributed among time point groups for sacrifice up to 6 weeks. All animals underwent bilateral surgery (total N = 180). Biomechanical, histologic, and molecular analyses were performed to identify and quantify the progression of changes in the supraspinatus tendon. Decreases in failure force and stiffness were found in impinged tendon specimens compared to sham and no-surgery controls at all study time points. Semi-quantitative scoring of histologic specimens demonstrated significant, persistent tendinopathic changes over 6 weeks. Quantitative real-time polymerase chain reaction analysis of impinged tendon specimens demonstrated persistently increased expression of genes related to matrix remodeling, inflammation, and tendon development. Overall, this novel murine subacromial impingement model creates changes consistent with acute tendonitis, which may mimic the early stages of rotator cuff tendinopathy. A robust, simple, and reproducible animal model of rotator cuff tendinopathy is a valuable research tool to allow further studies of cellular and molecular mechanisms and evaluation of therapeutic interventions in rotator cuff tendinopathy. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2780-2788, 2018.

More histologic and ultrastructural degenerative signs in the subscapularis tendon and the joint capsule in male patients with shoulder impingement.

PURPOSE: The purpose of the present study was to analyze biopsy samples from the subscapularis tendon and from the joint capsule from male patients with shoulder impingement syndrome (SAIS) and compare them with samples from male patients with post-traumatic recurrent shoulder instability. The hypothesis of the study was that patients with SAIS would have more histologic and ultrastructural degenerative changes in their subscapularis tendon and joint capsule than patients with post-traumatic recurrent shoulder instability. METHODS: Male patients scheduled for surgery, with either subacromial decompression or Bankart reconstruction, were included. Four biopsies from each patient were obtained from the capsule and four from the subscapularis tendon during arthroscopic surgery. The histologic characteristics and the presence of glycosaminoglycans were assessed using the light microscope, and the ultrastructure was assessed using a transmission electron microscope. RESULTS: Eight patients, median age 53 (45-74) years (p < 0.0001), were included in the impingement group, and 12 patients, median age 27 (22-48) years, were included in the instability group. The histologic assessment revealed significantly higher cellularity and total degeneration score in the capsule (p = 0.016 and p = 0.014 respectively) in patients with subacromial impingement compared with the instability patients. The corresponding finding was not made for the subscapularis tendon. The ultrastructural evaluation revealed that the instability patients had more fibrils with a large diameter (indicating less degeneration) in both the subscapularis tendon and the capsule compared with the impingement patients (p < 0.0001). CONCLUSION: Male patients with subacromial impingement have more histologic and ultrastructural degenerative changes in their shoulder compared with patients with post-traumatic recurrent shoulder instability. CLINICAL RELEVANCE: It appears that in patients with subacromial impingement, the whole shoulder joint is affected and not only the subacromial space. It is the opinion of the authors that intra-articular therapeutic injections could be tried more often in these patients. LEVEL OF EVIDENCE: III.

The role of scapular kinematics in patients with different shoulder musculoskeletal disorders: A systematic review approach.

This study aimed to identify the role of the scapula in shoulder musculoskeletal disorders (SMDs) and provided a systematic review of available studies in the field of scapular three-dimensional kinematics. We systematically searched 5 international databases, including Scopus, EMBASE, PubMed, CINAHL, PEDro, and Cochrane Library from June to September 2015. Twenty studies met the inclusion criteria and were retrieved in full paper. The selected studies were critically appraised independently by two researchers. The patients with shoulder impingement syndrome (SIS) and shoulder instability had an increased protraction, lesser upward rotation (UR), and increased internal rotation (IR) during scapular plane elevation, whereas the patients with frozen shoulders had lesser protraction. Moreover, the patients with SIS had a greater scapular posterior tilt (PT) and external rotation during shoulder abduction. Increased scapular UR and PT with decreased scapular IR was seen in patients with stiffness of Latissimus Dorsi and fibromyalgia without any changes in the scapular IR. The results of this systematic review help the clinicians to have an insight about scapular kinematics as a predictive index for SMDs.

Tendon Volume Determination on Magnetic Resonance Imaging of Supraspinatus Tendinopathy.

OBJECTIVE: To determine the supraspinatus tendon volume using magnetic resonance imaging (MRI) in dogs with non-calcified supraspinatus tendinopathy (NCST), in dogs with orthopedic disease other than NCST, and in healthy dogs. STUDY DESIGN: Case series. ANIMALS: Twenty-two dogs (18 client-owned dogs; 4 purpose-bred dogs). METHODS: Dogs undergoing shoulder MRI were categorized as NCST if they were diagnosed with NCST only, had histologic confirmed diagnosis, underwent surgical treatment, and were available for follow-up longer than 4 months. Dogs with MRI performed for a forelimb lameness because of a diagnosis other than NCST were categorized as orthopedic control (OC). Healthy dogs from an unrelated study were categorized as healthy controls (HC). Tendon volume was determined from MRI using public domain software and compared across categories. RESULTS: The study included 9 NCST dogs, 9 OC dogs, and 4 HC dogs. The median tendon volume for NCST was 1,323 mm(3), OC was 630 mm(3), and HC was 512 mm(3). The volume was significantly higher in the NCST than OC (P = .0012) and HC (P = .003). There was no difference between OC and HC (P = .76). CONCLUSION: Dogs diagnosed with NCST had higher supraspinatus tendon volumes compared to dogs with other orthopedic disorders and healthy dogs.

The effect of glenoid cavity depth on rotator cuff tendinitis.

INTRODUCTION: Some of the most important causes of shoulder pain are inflammation and degenerative changes in the rotator cuff (RC). Magnetic resonance imaging (MRI) is a noninvasive and safe imaging modality. MRI can be used for the evaluation of cuff tendinopathy. In this study, we evaluated the relationship between glenoid cavity depth and cuff tendinopathy and we investigated glenoid cavity depth on the pathogenesis of cuff tendinopathy. MATERIALS AND METHODS: We retrospectively evaluated 215 patients who underwent MRI. Of these, 60 patients showed cuff tendinopathy (group A) and 54 patients showed no pathology (group B). Glenoid cavity depth was calculated in the coronal and transverse planes. RESULTS: The mean axial depth was 1.7 ± 0.9 and the mean coronal depth 3.8 ± 0.9, for group A. The mean axial depth was 3.5 ± 0.7 and the mean coronal depth 1.5 ± 0.8, for group B. There were significant differences in the axial and coronal depths between the two groups. CONCLUSION: High coronal and low axial depth of the glenoid cavity can be used to diagnose RC tendinitis.

Posterosuperior glenoid internal impingement of the shoulder in the overhead athlete: pathogenesis, clinical features and MR imaging findings.

Posterosuperior glenoid internal impingement (PGII) is an impingement syndrome of the shoulder that is most commonly seen in the throwing or overhead athlete. The supraspinatus can be normally compressed or impinged between the greater tuberosity and the posterosuperior labrum in the abduction and external rotation position. However, repetitive throwing and biomechanical abnormalities may lead to the intensification of this contact and to the clinical and pathological picture of PGII. The injured athlete usually complains of poor throwing performance and pain located in the posterosuperior aspect of the shoulder. Two main theories regarding the aetiology of PGII have been postulated with differing initial mechanisms. The MRI features of PGII have been described and include supraspinatus and anterior infraspinatus partial undersurface tears, bony changes at the humeral head and labral pathology, including a variation of the type II superior labrum from anterior to posterior lesion. This pictorial essay aims to present cases illustrating the pathophysiology, clinical features and recently described MRI findings, and discuss some of the MR protocol considerations.

MRI analysis of coracohumeral interval width and its relation to rotator cuff tear.

OBJECTIVE: Coracoid impingement is an uncommon cause of the shoulder pain. It is stimulated by adduction, internal rotation and forward flexion. These positions decrease the width of the coracohumeral interval. Owing to restriction of movement, rotator cuff tendons may be overloaded. Thus, in this study, we aimed to determine whether coracoid impingement increase the tendency of rotator cuff tears. MATERIALS AND METHODS: Routine clinical MRI sequences of 117 shoulders were reviewed, and axial coracohumeral interval measurements were taken. Rotator cuff tendon integrity was evaluated. Relation between rotator cuff tear and coracohumeral interval width was commented statically. RESULTS: Seventy-nine of the patients were women, 38 of them men. The average age was 44.8 ± 14.2 (14-75). The mean age of patients with rotator cuff tear was significantly higher than patients without tear (p = 0.001). The mean value of coracohumeral interval width was 8.853 ± 2.491 mm (min: 2.9-max: 15.8). There were no significant differences between coracohumeral interval width of women and men (p = 0.139). The mean value of coracohumeral interval width with rotator cuff tear was 8.362 ± 2.382, and without tear was 9.351 ± 2.520. There was a significant differences between them (p = 0.031). CONCLUSION: According to our study, there was a relationship between coracohumeral interval width and rotator cuff tear, so decreasing coracohumeral interval width may increase tendency of rotator cuff tear.

Effects of conservative therapy applied before arthroscopic subacromial decompression on the clinical outcome in patients with stage 2 shoulder impingement syndrome.

BACKGROUND/AIM: To investigate the effects of conservative therapy applied before arthroscopic subacromial decompression on the clinical outcome in patients with stage 2 shoulder impingement syndrome. MATERIALS AND METHODS: Sixty-eight patients having stage 2 shoulder impingement syndrome and treated with arthroscopic subacromial decompression were included in the study. We divided these patients into 2 groups, whereby 32 (47%) patients received conservative therapy before arthroscopic subacromial decompression and 36 (53%) patients did not receive conservative therapy. We compared both groups in terms of the the Constant, UCLA, and VAS scores for shoulder pain before and after arthroscopic subacromial decompression. RESULTS: Constant, UCLA, and VAS scores were statistically significantly improved in both groups after arthroscopic subacromial decompression (P <0.001). Constant, UCLA, and VAS scores before arthroscopic subacromial decompression were statistically better in Group 1 than in Group 2 (P < 0.001). No statistically significant difference was found between the groups in terms of Constant, UCLA, and VAS scores after arthroscopic subacromial decompression (P > 0.05). CONCLUSION: Conservative therapy applied in patients with stage 2 shoulder impingement syndrome before arthroscopic subacromial decompression does not have a positive contribution on the clinical outcome after arthroscopic subacromial decompression.

Acromial morphology in patients with calcific tendinitis of the shoulder.

PURPOSE: The purpose of this study was to evaluate whether the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement. METHODS: Digital radiographs of 150 shoulders were evaluated with the open source DICOM-Viewer OsiriX. 50 patients had symptomatic calcific tendinitis of the shoulder, 50 had subacromial impingement without calcifications or rotator cuff tears, 50 with bruised shoulder that were previously asymptomatic served as controls. Acromial shape according to Bigliani et al. acromial tilt (AT) according to Kitay et al. and Aoki et al. acromion index (AI) according to Nyffeler et al. and lateral acromial angle (LAA) according to Banas et al. were measured. RESULTS: Both calcific (0.72; P = 0.001) and impingement groups (0.73; P = 0.008) were significantly different from controls (0.67) using AI measure, while only the calcific group (79.5°) was different from controls (84.1°) using LAA (P < 0.001), and only the impingement group (32.9°) was different from controls (29.2°) using AT (P < 0.001). An LAA <70° only occurred in two patients with calcific tendinitis. CONCLUSION: The hypothesis of this study was that the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement was only confirmed for the AI. The AI of shoulders with calcific tendinitis is comparable to that of shoulders with subacromial impingement.

[Establishment of microinvasive modle of chronic rotator cuff injury in rats].

OBJECTIVE: To establish a model of chronic rotator cuff injury by inducing subacromial impingement syndrome in rats, so as to lay a foundation for further study on the mechanism and treatment of chronic rotator cuff injury. METHODS: The polyether-ether-ketone implants were designed and made with three-dimensional printing technique. In 48 male Sprague Dawley rats [weighing, (277.25 ± 22.03) g], one shoulder joint was selected randomly as the experimental group; in the experimental group, the implant was pierced into shoulder joint close to the acromion medial side and was pierced out under acromion close to the deltoid trailing edge; the penetrating part of implant was cut off after the implanting part was fixed with 4# braided silk suture. No any treatment was performed on the contralateral shoulder of 24 rats as control group; and the implants were immediately removed after they were pierced into the contralateral shoulder joint of the other 24 rats as sham- operation group. All the rats were exposed to 30 minutes of downhill running at 17 m/minute (-13.5°) every day at 4 days after operation and the general condition of rats was observed. At 2, 4, 6, and 8 weeks after operation, 12 rats were sacrificed to collect shoulder joint samples. The hard tissue slices was used for Van Gieson staining and histological observation of the supraspinatus tendon. RESULTS: All rats survived to the end of experiment, without infection. The rats suffered limp at 2-3 days after operation, and the gait of most rats returned to normal at 4 days after operation. The histological results showed that the supraspinatus tendon had smooth edge, without split layers or breakage in the control group and sham-operation group. In the experimental group, the implants were positioned accurately without dislocation; 4 kinds of typical pathological changes were observed. Partial-thickness tear on bursal side appeared at 2 weeks (5 rats) and 4 weeks (2 rats), showing no significant difference between at 2 and 4 weeks (P > 0.05); intratendinous gap formed mainly at 4 weeks (10 rats) and 6 weeks (11 rats), showing significant differences when compared with that at 2 weeks (2 rats) (P < 0.05) and 8 weeks (2 rats) (P < 0.05); partial-thickness tear on articular side mainly appeared at 6 weeks (8 rats), showing significant difference when compared with that at other time points (P < 0.05); full-thickness tear was found mainly at 8 weeks (10 rats), showing significant differences when compared with that at other time points (P < 0.05). CONCLUSION: A model of chronic rotator cuff injury is successfully established in rats through microinvasive implantation of subacromial impingement syndrome inducing implants and the pathological changes in this model are highly similar to the clinical pathological progress.

The upper extremity musculoskeletal complications in dialysis patients: comparison between hemodialysis and peritoneal dialysis.

OBJECTIVES: The aim of this study was to compare the upper extremity musculoskeletal complications in the patients who had been receiving hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). MATERIAL AND METHODS: The patients who had been receiving HD (n=17) or CAPD (n=15) were included to the study. The age, gender, duration of dialysis were recorded. The physical findings related to musculoskeletal system in the upper extremity were researched. The cervical, shoulder, hand standard radiographies and shoulder magnetic resonance imaging were investigated. RESULTS: The mean duration of HD and CAPD were 53.60 ± 36.03 and 49.17 ± 33.14 months, respectively (p=0.720). Only 6.3% of the CAPD group had signs of carpal tunnel syndrome (CTS). There were not any differences in the frequency of cervical destructive spondyloarthropathy, decreased height of vertebral corpus in the examination of cervical radiography (p=0.579) and also in the frequency of erosions in the humeral head and bones of hand, cyst in the clavicula, erosive osteoarthropathy and osteoporosis detected in the bones of hands (p> 0.005). In the examination of shoulder MR imaging, 80% of the HD group and 47.1% of the CAPD group had supraspinatus tendinitis (p=0.059). The frequency of subscapularis, biceps and infraspinatus tendinitis were not different in HD and CAPD groups (p> 0.05). CONCLUSION: The musculoskeletal system complications of the upper extremity were common in the patients undergoing dialysis therapy. The most common complications were osteoporosis of the hand region and supraspinatus tendinitis. LEVEL OF EVIDENCE: Prospective, Level 2b.

Effect of plane of arm elevation on glenohumeral kinematics: a normative biplane fluoroscopy study.

BACKGROUND: Understanding glenohumeral motion in normal and pathologic states requires the precise measurement of shoulder kinematics. The effect of the plane of arm elevation on glenohumeral translations and rotations remains largely unknown. The purpose of this study was to measure the three-dimensional glenohumeral translations and rotations during arm elevation in healthy subjects. METHODS: Eight male subjects performed scaption and forward flexion, and five subjects (three men and two women) performed abduction, inside a dynamic biplane fluoroscopy system. Bone geometries were extracted from computed tomography images and used to determine the three-dimensional position and orientation of the humerus and scapula in individual frames. Descriptive statistics were determined for glenohumeral joint rotations and translations, and linear regressions were performed to calculate the scapulohumeral rhythm ratio. RESULTS: The scapulohumeral rhythm ratio was 2.0 ± 0.4:1 for abduction, 1.6 ± 0.5:1 for scaption, and 1.1 ± 0.3:1 for forward flexion, with the ratio for forward flexion being significantly lower than that for abduction (p = 0.002). Humeral head excursion was largest in abduction (5.1 ± 1.1 mm) and smallest in scaption (2.4 ± 0.6 mm) (p < 0.001). The direction of translation, as determined by the linear regression slope, was more inferior during abduction (-2.1 ± 1.8 mm/90°) compared with forward flexion (0.1 ± 10.9 mm/90°) (p = 0.024). CONCLUSIONS: Scapulohumeral rhythm significantly decreased as the plane of arm elevation moved in an anterior arc from abduction to forward flexion. The amount of physiologic glenohumeral excursion varied significantly with the plane of elevation, was smallest for scaption, and showed inconsistent patterns across subjects with the exception of consistent inferior translation during abduction.

The role of radiological subacromial distance measurements in the subacromial impingement syndrome.

Subacromial impingement is one of the most common causes of painful shoulder in the middle aged and elderly population. Since Neer's first description of the process, many investigators have researched this condition in an effort to gain a better understanding of the disease etiology. The aim of this study was to investigate the relationship between the radiological subacromial distance measurements and the subacromial impingement syndrome in a series of patients from our institution. For this purpose, 44 patients scheduled for a unilateral shoulder arthroscopy were investigated prospectively. The acromio-glenoid angle, supraspinatus-glenoid angle (from coronal MR images) and acromial index (from true anterior-posterior shoulder X-ray images) were measured as the implications of the subacromial distance, and the degree of subacromial impingement was graded according to intraoperative findings. Statistical data analysis revealed no significant correlations between the radiological measurements and the severity of subacromial impingement (p > 0.05). On the other hand, there was a significant correlation (p = 0.0049) between the patient age and subacromial impingement. These results suggest that the radiological subacromial distance measurements do not have enough clinical significance as predictive markers in the subacromial impingement syndrome.

Bone grafting of humeral head cystic defects during rotator cuff repair.

Cystic bony defects of the humeral head greater tuberosity are often encountered during rotator cuff repair. These defects may be idiopathic, related to a patient's rotator cuff disease, or secondary to suture anchor placement from previous repairs. Some cysts are visible on preoperative magnetic resonance imaging, but most are discovered on footprint exploration or implant removal during revision surgery. These osseous defects reduce biological healing capacity and may decrease repair fixation strength. Bone grafting techniques are needed to address these defects. In this article, we present an arthroscopic allograft compaction technique with concomitant suture anchor rotator cuff repair.

Subacromial impingement syndrome.

Subacromial impingement syndrome (SIS) represents a spectrum of pathology ranging from subacromial bursitis to rotator cuff tendinopathy and full-thickness rotator cuff tears. The relationship between subacromial impingement and rotator cuff disease in the etiology of rotator cuff injury is a matter of debate. Both extrinsic compression and intrinsic degeneration may play a role. Management includes physical therapy, injections, and, for some patients, surgery. There remains a need for high-quality studies of the pathology, etiology, and management of SIS.

Pain mapping for common shoulder disorders.

We conducted a study to ascertain specific patterns of pain in patients with common shoulder disorders and to describe a comprehensive shoulder pain map. We prospectively studied 94 cases involving an upper limb pain map and correlated the maps with the final diagnoses made by 2 clinicians who were blinded to the pain map findings. Pattern, severity, and type of pain were specific to each common shoulder disorder. In subacromial impingement, pain was predominantly sharp, occurred around the anterior aspect of the shoulder, radiated down the arm, and was associated with dull, aching pain radiating to the hand. A similar pain pattern was found in rotator cuff tears. In acromioclavicular joint pathology, pain was sharp, stabbing, and well localized to the anterosuperior shoulder area. Glenohumeral joint arthritis was marked by the most severe pain, which occurred in a mixed pattern and affected the entire arm. Whereas the pain of instability was a mixture of sharp and dull pain, the pain of calcific tendonitis was severe and sharp. Both pains were limited to the upper arm and shoulder. Pain mapping revealed definitive patterns for shoulder pathologies. We advocate using pain maps as useful diagnostic guides and research tools.

Subacromial osteochondroma.

The most common cause of impingement syndrome is mechanical irritation of the subacromial bursa and rotator cuff by the coracoacromial arch. Offending structures include the undersurface of the anterolateral acromion, coracoacromial ligament, and the undersurface of the distal clavicle. We present a case of impingement syndrome caused by mechanical irritation of the rotator cuff by a subacromial osteochondroma that was successfully treated with arthroscopic resection. Osteochondroma is the second most common benign bone tumor following nonossifying fibroma. These lesions are thought to arise from aberrant growth of normal epiphyseal growth plate cartilage. Ninety percent of osteochondromas arise from the metaphyseal regions of long bones (eg, distal femur, proximal tibia, or proximal humerus). Scapular involvement accounts for 3.0% to 4.6% of all reported osteochondromas. These lesions represent 14.4% of all tumors of the scapula and 49% of benign scapular tumors, making them the most common benign bone tumors of the scapula. Our patient failed nonoperative management of his subacromial osteochondroma. The concern for malignant transformation was low, as the patient's pain had been consistent for the past 15 years. Although his pain had been largely unchanged for more than a decade, he elected to undergo resection so that he could resume the hobbies that his pain had forced him to abandon. He reported substantial pain relief and restoration of function following arthroscopic resection and subacromial decompression, reinforcing mechanical irritation of the rotator cuff as the source of his shoulder pain and dysfunction. To our knowledge, this is the first report of arthroscopic resection of a subacromial osteochondroma.