The vascularity of the rotator cuff

The major arterial supply to the rotator cuff is derived from the ascending branch of the anterior humeral circumflex artery, the acromial branch of the thoracoacromial artery, as well as the suprascapular and posterior humeral circumflex arteries. The pathogenesis of rotator cuff tears has been considered to be influenced by the microvascular supply of the rotator cuff tendons. Most cadaver studies have demonstrated a hypovascular area within the critical zone of the supraspinatus tendon. It has been suggested that this area of hypovascularity has a significant role in the attritional degeneration of the aging tendon. More recent studies of the microvascular supply to the supraspinatus tendon in symptomatic patients with impingement syndrome suggest that in the area of greatest impingement, i.e., the critical zone, there is actually hypervascularity. In contrast to the cadaver investigations, these studies seem to imply that hypervascularity or neovascularization is associated with symptomatic rotator cuff disease secondary to mechanical impingement.     

Fatty infiltration and atrophy of the rotator cuff do not improve after rotator cuff repair and correlate with poor functional outcome

BACKGROUND: The role of degenerative changes in rotator cuff musculature with respect to the functional outcomes of rotator cuff repair have only recently been recognized and are still not well understood. In addition, the reversibility of these changes with repair of the tendons is questionable. HYPOTHESIS: Poorer preoperative muscle quality negatively affects outcome, and a successful outcome (in terms of a healed repair) might demonstrate improvements in fatty infiltration and muscle atrophy. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Thirty-eight patients (mean age, 62 years) were prospectively evaluated with preoperative and 1-year postoperative clinical examination and appropriate magnetic resonance image sequencing to determine grades of muscle atrophy and fatty infiltration of the supraspinatus and infraspinatus muscles. American Shoulder and Elbow Society (ASES), Constant, and pain scores were determined as well as strength measurements. The retear rate and progression of muscle degeneration were also evaluated. Independent predictors of outcome measurements and cuff integrity were determined. RESULTS: The overall clinical outcome, including ASES, Constant, and pain scores, improved significantly (P < .0001). Strength in forward elevation improved significantly (P < .006), while external rotation strength did not. There was a strongly negative correlation between muscle quality and outcome results in most cases. When the results were adjusted for multivariate effect, muscle atrophy and fatty infiltration of the infraspinatus muscle were the only independent predictors of ASES and Constant scores (P < .03). Tear size and rotator cuff healing did not play an independent role. Tear size, however, was the only independent predictor of ultimate cuff integrity (P = .002). Both atrophy and fatty infiltration progressed significantly over the course of the study. In cases in which the tendon had re-torn, the progression was found to be more significant than when the repair proved successful (P < .003). CONCLUSION: Muscle atrophy and fatty infiltration of the rotator cuff muscles, particularly of the infraspinatus, play a significant role in determining functional outcome after cuff repair. Tear size appears to have the most influential effect on repair integrity. A successful repair did not lead to improvement or reversal of muscle degeneration and a failed repair resulted in significantly more progression. In general, healed repairs demonstrated minimal progression. These findings suggest that repairs should be performed, if possible, before more significant deterioration in the cuff musculature in order to optimize outcomes, and that understanding the degree of muscle atrophy and fatty infiltration before surgery can help guide patient expectations.     

Arthroscopic rotator cuff repair

The use of the arthroscope to address shoulder pathology is continuously evolving. Many aspects of shoulder arthroscopy are readily accepted and used by orthopedic surgeons, but some procedures can be technically difficult. Arthroscopic rotator cuff repair has traditionally involved the use of cumbersome knot tying techniques, deterring many surgeons from using this technique. Although open and mini-open rotator cuff repair is commonly used with predictable results, there still remains inherent morbidity to any open technique. This article will outline a technique that avoids knot tying and suture management in arthroscopic rotator cuff repair. Although the indications are evolving, arthroscopic rotator cuff repair allows predictable results with excellent pain relief and return to function.     

Partial-thickness rotator cuff tears

Partial-thickness tears of the rotator cuff have been diagnosed with increased frequency because of a heightened awareness of the condition by clinicians and improved diagnostic methods. Research into the causes, natural history, and optimal treatment of this condition lags behind that of full-thickness tears. However, despite the limitations in the existing literature, there has emerged a consensus among shoulder experts that partial-thickness rotator cuff tears should be aggressively treated in the active athlete because of the unfavorable natural history of these lesions and success of accepted surgical algorithms. This review will provide an overview of the theories regarding the origins of partial-thickness rotator cuff tears, discuss the relative accuracy of accepted diagnostic techniques, and summarize the indications and methods of operative repair with an emphasis on the results of various treatment approaches.     

Scoring systems for the functional assessment of patients with rotator cuff pathology

Ideally, an outcome instrument measures phenomena that are directly relevant to the patient and provides a comprehensive assessment of the impact of a condition on the patient's daily life. During the past decades, several rating scales have been developed to assess the functional status of patients with shoulder pain. Several scoring systems are currently available for the evaluation of patients with rotator cuff pathology. Each of them evaluates shoulder function using specific variables. The main features of these scoring systems are presented in this review. Although many scoring systems are commonly used to evaluate shoulder function, we are still far from a single outcome evaluation system, which is reliable, valid, and sensitive to clinically relevant changes, takes into account both patient's and physician's perspective, and is short and practical to use.     

Neoinnervation in rotator cuff tendinopathy

The aim of this study was to determine whether there are more nerves in tendinopathic human tendon, and if so, where are they located. Tendon biopsies were collected from normal, tendinopathic, and torn human rotator cuff tendons and then analyzed using immunohistochemistry and antibodies against a general nerve marker (protein gene product 9.5, PGP9.5), a nerve regeneration marker (growth-associated protein 43, GAP43), and an endothelial cell marker (CD34). Nerve fibers exhibiting PGP9.5 or GAP43 immunoreactivity were often observed intimately in association with tiny blood vessels in the endotendineum of tendinopathic tendons. The expression of PGP9.5 and GAP43 were significantly higher in tendinopathic tendon compared with control tendon and torn tendon. These data support the hypothesis that early tendinopathy is associated with increases of newly grown nerve fibers and blood vessels inside and around tendinopathic tendon, and these may be the source of pain in tendinopathy.     

Imaging of the rotator cuff

The imaging evaluation of the rotator cuff augments the clinical evaluation. Radiography, computed tomography, and magnetic resonance imaging all have various roles in the assessment of the rotator cuff, which can be combined with arthrography for added detail. Furthermore, ultrasound is a very useful technique that provides functional information that is not offered by simple anatomic imaging.     

Ultrasonography of the rotator cuff

The authors suggest that sonography may be the best screening study for the diagnosis of rotator cuff tears.     

Histopathology of rotator cuff tears

The pathogenesis of rotator cuff tears is multifactorial. Tendon abnormalities of the rotator cuff include alteration of collagen fiber structure, tenocytes, cellularity, and vascularity. Ruptured tendons show marked collagen degeneration and disordered arrangement of collagen fibers. Fibroblast population decreases as the size of the tear in the rotator cuff increases. The larger fibroblast population seen in the smaller tears is also actively proliferating and is part of an active reparative process. Inflammatory cell infiltrate correlates inversely to rotator cuff tear size in the torn supraspinatus tendon samples, with larger tears showing a marked reduction in all cell types. As tear size increase, there is also a progressive decrease in the number of blood vessels. Whether rotator cuff tear heals spontaneously is an important pathologic and clinical question. Histologic changes indicative of repair and inflammation lead to consider biological options in addition to biomechanical treatment of the rotator cuff tears.     

Rehabilitation of rotator cuff tendinopathy

Rehabilitation of the dysfunction that is associated with rotator cuff tendinopathy should be based on the evidence known about the pathoetiology of the tendinopathy, what is known about the extent of the local anatomic injury, the local and distant physiological and biomechanical alterations, and on the knowledge developed regarding progressive loading of the injured or altered structures. Prehabilitation, or prospective exercises to minimize future rotator cuff loading stresses, should be included at the end of rehabilitation as part of the return to function.     

All arthroscopic rotator cuff repairs

The arthroscopic operation for repair of full-thickness rotator cuff tears is successful and has the advantages ofglenohumeral joint inspection, treatment of intra-articular lesions, smaller incisions, no deltoid detachment, less soft tissue dissection, less pain, and more rapid rehabilitation. However, these advantages must be balanced against the technical difficulty of the method, which limits its application to surgeons skilled in both open and arthroscopic shoulder operations. This article contains many technical pearls to, as much as is possible, simplify and improve all arthroscopic cuff repair.     

Pitfalls of rotator cuff sonography

Experience with rotator cuff sonography in 106 patients was analyzed to identify the causes of scan misinterpretation. Possible interpretive errors may be classified into four categories: those from failure to recognize normal anatomy, those caused by soft-tissue abnormalities, those caused by bony abnormalities, and those caused by technical limitations of the study. Errors in recognition of normal anatomy are easily overcome by experience and comparison to the normal, contralateral rotator cuff. Errors resulting from soft-tissue abnormalities were seen in two patients with calcific tendinitis simulating rotator cuff tears. Problems in interpretation resulting from fractures in two patients and inferior glenohumeral subluxation in two other patients could have been avoided by review of the plain films before performing sonography. The major technical limitation of the study arises from the inability to image the rotator cuff beneath the acromion. Fortunately, rotator cuff tears are rarely isolated in this location, and passive maneuvers often allow otherwise hidden parts of the cuff to be imaged.     

The relationship of acromial architecture to rotator cuff disease

Variations in the architecture of the coracoacromial arch can lead to a clinically symptomatic rotator cuff lesion. Differences in the development and morphology of the acromion, and the presence of anterior acromial spurs and inferior acromioclavicular osteophytes decrease the volume of the subacromial space, leading to impingement. Recent anatomic, radiographic, biomechanical, and SPG studies have confirmed these architectural variations and their effects on the contents of the subacromial space. Abnormal contact between the acromion and these soft tissues can lead to pathologic lesions. Surgical procedures should be directed at increasing the space beneath the coracoacromial arch to reduce wear on the rotator cuff.