Musculotendinous infraspinatus ruptures: an overview

Rotator cuff tear patterns: MRI appearance and its surgical relevance

A new perspective on rotator cuff anatomy has allowed a better understanding of the patterns of the different rotator cuff tears. It is essential for radiologists to be aware of these different patterns of tears and to understand how they might influence treatment and surgical approach. Our objective is to review the arthroscopy correlated magnetic resonance imaging appearance of the different types of rotator cuff tears based on current anatomical concepts.Critical relevance statement Knowledge of the characteristics of rotator cuff tears improves our communication with the surgeon and can also make it easier for the radiologist to prepare a report that guides therapeutic conduct and serves as a prognosis for the patient.Key points• There is no universally accepted classification for RC tears.• New patterns such as delamination or myotendinous junction tears have been defined.• The most difficult feature to assess in full thickness tears on MRI is the pattern.• Fatty infiltration of the RC tendons is crucial in the prognosis and outcome.• The radiological report is an effective way of communication with the surgeon.

Arthroscopy Technique: Repair of Musculotendinous Junction Rotator Cuff Tears in the Shoulder Using a Dynamic Convergence Suture Bridge Technique

Musculotendinous junction (MTJ) rotator cuff tears in the shoulder are rare injuries in which the tendon fails medial to its tuberosity attachment. There is difficulty in striking a balance between restoring the length-tension relationship of the tendon while avoiding high suture tension at the repair site. In view of the rare incidences of these tears, there is a paucity of literature on their repair techniques. We seek to share our surgical technique in addressing type A MTJ tears-where the medial muscular tear margin is short but remains adequate for suture bridge repair, whereas the lateral tendon remains on the footprint. We used mattress sutures from the medial row of anchors, threaded through the lateral tendon stump, then passed medially to engage the medial stump, before being fixed to a lateral row in a knotless fashion. Pulling on this pair of sutures will thus bring into closer apposition of both medial and lateral tear margins in a dynamic convergence pattern. Our surgical technique is a safe and effective method of repairing type A MTJ tear that confers improved biological and biomechanical advantage via the formation of a dynamic convergence suture bridging technique in addition to a double-row repair construct.

Muscle Edema of Retraction and Pseudo-Fatty Infiltration After Traumatic Rotator Cuff Tears: An Experimental Model in Sheep

Background

Traumatic rotator cuff tears can result in retraction of the tendon and may be associated with muscle edema, which may be confused with fatty infiltration as seen on magnetic resonance imaging (MRI).

Purpose

To describe the characteristics of a type of edema associated with acute retraction of the rotator cuff tendon (termed "edema of retraction") and to highlight the risk of mistaking it with pseudo-fatty infiltration of the rotator cuff muscle.

Study Design

Descriptive laboratory study.

Methods

A total of 12 alpine sheep were used for analysis. On the right shoulder, osteotomy of the greater tuberosity was performed to release the infraspinatus tendon; the contralateral limb acted as the control. MRI was performed immediately after surgery (time zero) and at 2 and 4 weeks postoperatively. T1-weighted, T2-weighted, and Dixon pure-fat sequences were reviewed for hyperintense signals.

Results

Edema of retraction resulted in hyperintense signals around or within the retracted rotator cuff muscle on both T1- and T2-weighted imaging, but there was an absence of hyperintense signals on Dixon pure-fat imaging. This represented pseudo-fatty infiltration. Edema of retraction created a characteristic "ground glass" appearance of the muscle on T1-weighted sequences and was often found in either the perimuscular or intramuscular location of the rotator cuff muscle. Compared to time zero values, a decrease in the percentage of fatty infiltration was observed at 4 weeks postoperatively (16.5% ± 4.0% vs 13.8% ± 2.9%, respectively; P < .005).

Conclusion

The location of edema of retraction was often peri- or intramuscular. Edema of retraction presented as a characteristic "ground glass" appearance of the muscle on T1-weighted sequences and led to a decrease in the fat percentage because of a dilution effect.

Clinical Relevance

Physicians should be aware that this edema can result in a form of pseudo-fatty infiltration, as it is associated with hyperintense signals on both T1- and T2-weighted sequences, and it can be mistaken for fatty infiltration.

Studying Edema Formation After Release of the Infraspinatus Tendon as an Experimental Model of Rotator Cuff Tears in Sheep: A Preliminary Imaging and Morphological Analysis

BACKGROUND

The cause, extent, and role of muscle edema for muscle degeneration are unknown and not considered in the current literature. In vivo experiments were designed to prove muscle edema formation in the early period in a sheep model of acute rotator cuff tears.

HYPOTHESIS

Muscle edema occurs after tendon release with or without additional stretching trauma and may be associated with muscle retraction and subsequent muscle degeneration.

STUDY DESIGN

Controlled laboratory study.

METHODS

A sheep model with acute release of the infraspinatus tendon was used. An osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed in 14 sheep. To demonstrate presence of edema, magnetic resonance imaging scans were performed at 0, 2, and 4 weeks using T1-weighted, T2-weighted, proton density-weighted, and Dixon sequences. Excisional biopsy specimens were taken at 0, 3, and 4 weeks (histological results will be reported in a later publication). Two injury models were created: a nontrauma group that consisted of muscle release alone and a trauma group that included additional standardized traction to the musculotendinous unit. Evaluation of T1- and T2-weighted images included calculation of pennation angle, muscle fiber length, signal intensity (edema), and muscle volume. Muscle wet weight and volume were measured at sacrifice.

RESULTS

Edema formation was shown in all sheep and slightly more pronounced in the trauma group, where muscle intensity increased significantly between time point 0 (200 Grey Value (GV)) and weeks 2, 3, and 4 (300 GV). Edema formation started early after tendon release with a plateau between 3 and 4 weeks. Deterioration of muscle fiber bundles began also after tendon release with a peak at 4 weeks. Muscle volume decreased steadily over time.

CONCLUSION

Muscle edema appeared early after rotator cuff tendon release, was more pronounced in the trauma group, and reached a plateau after 3 to 4 weeks. Muscle fatty content decreased within the short period of 4 weeks owing to a dilution effect. Muscle edema seems to be an essential factor in cuff tears and subsequent muscle retraction and degeneration.

CLINICAL RELEVANCE

This study demonstrates a new type of muscle edema of retraction and describes the characteristics of edema associated with a retracted rotator cuff tear.

Isolated infraspinatus musculotendinous junction tear treated with open repair and dermal allograft augmentation: a case report with 5-year outcome

We report the 5-year outcome of an isolated, atraumatic full-thickness infraspinatus myotendinous junction tear treated with open surgical repair. The index patient developed severe pain and weakness in external rotation strength following a subacromial corticosteroid injection. Magnetic resonance imaging and ultrasound of the shoulder demonstrated a full-thickness myotendinous junction tear with extensive muscle edema, mild atrophy and a spinoglenoid notch varix. Due to persistent, worsening pain and presence of ER weakness, the patient underwent primary infraspinatus muscle–tendon repair with allograft augmentation via an arthroscopic-assisted open posterior approach. The patient had an uneventful postoperative course with a resolution of pain and improvement in ER strength, which is maintained at the latest 5-year follow-up. This case report highlights a favorable long-term outcome of an isolated infraspinatus myotendinous junction tear treated with primary muscle–tendon repair and dermal allograft augmentation.

Partial thickness tear of the supraspinatus at the musculotendinous junction in a softball catcher

We report a rare case of a partial thickness tear of the supraspinatus at the musculotendinous junction in a softball catcher. Preoperative magnetic resonance images of the shoulder showed high signal intensity areas at the musculotendinous junction, along with discontinuity of the articular side of the supraspinatus. Arthroscopic examination revealed articular-side partial tear at the musculotendinous junction. The patient was able to return to playing softball 20 weeks after arthroscopic side-to-side repair. J. Med. Invest. 68 : 386-388, August, 2021.

Injuries in Muscle-Tendon-Bone Units: A Systematic Review Considering the Role of Passive Tissue Fatigue

Background:

Low-cycle fatigue damage accumulating to the point of structural failure has been recently reported at the origin of the human anterior cruciate ligament under strenuous repetitive loading. If this can occur in a ligament, low-cycle fatigue damage may also occur in the connective tissue of muscle-tendon units. To this end, we reviewed what is known about how, when, and where injuries of muscle-tendon units occur throughout the body.

Purpose:

To systematically review injuries in the muscle-tendon-bone complex; assess the site of injury (muscle belly, musculotendinous junction [MTJ], tendon/aponeurosis, tendon/aponeurosis–bone junction, and tendon/aponeurosis avulsion), incidence, muscles and tendons involved, mechanism of injury, and main symptoms; and consider the hypothesis that injury may often be consistent with the accumulation of multiscale material fatigue damage during repetitive submaximal loading regimens.

Methods:

PubMed, Web of Science, Scopus, and ProQuest were searched on July 24, 2019. Quality assessment was undertaken using ARRIVE, STROBE, and CARE (Animal Research: Reporting In Vivo Experiments, Strengthening the Reporting of Observational Studies in Epidemiology, and the Case Report Statement and Checklist, respectively).

Results:

Overall, 131 studies met the inclusion criteria, including 799 specimens and 2,823 patients who sustained 3,246 injuries. Laboratory studies showed a preponderance of failures at the MTJ, a viscoelastic behavior of muscle-tendon units, and damage accumulation at the MTJ with repetitive loading. Observational studies showed that 35% of injuries occurred in the tendon midsubstance; 28%, at the MTJ; 18%, at the tendon-bone junction; 13%, within the muscle belly and that 6% were tendon avulsions including a bone fragment. The biceps femoris was the most injured muscle (25%), followed by the supraspinatus (12%) and the Achilles tendon (9%). The most common symptoms were hematoma and/or swelling, tenderness, edema and muscle/tendon retraction. The onset of injury was consistent with tissue fatigue at all injury sites except for tendon avulsions, where 63% of the injuries were caused by an evident trauma.

Conclusion:

Excluding traumatic tendon avulsions, most injuries were consistent with the hypothesis that material fatigue damage accumulated during repetitive submaximal loading regimens. If supported by data from better imaging modalities, this has implications for improving injury detection, prevention, and training regimens.

Characterization of Infraspinatus Tendon Anatomy: The Soft-Tissue Portion of Remplissage

Purpose

To characterize the morphology of the infraspinatus (IS) tendon and evaluate the bony anatomy of the humeral head (HH) to determine if there is a correlation between HH measurements and the amount of available IS tendon.

Methods

The superior-inferior width as well as the medial-lateral (M-L) length of the inferior and superior portions of the IS tendon were measured in 15 human cadaveric shoulders. Three measurements were then obtained for each corresponding humeral head: (1) anterior to posterior (A-P) distance, (2) midcoronal humeral head distance (MCHH), and (3) M-L distance. Pearson correlation coefficients (R) of tendon measurements relative to HH measurements were determined.

Results

The mean ± SD HH measurements were 44.3 ± 3.3 mm for A-P, 49.3 ± 3.4 mm at the MCHH, and 52.2 ± 3.4 mm in the M-L plane. The mean M-L length of the superior portion of the IS tendon was significantly different from the inferior portion (42.4 vs 31.0 mm, P < .0001). The mean ± SD width of the IS tendon was 19.4 ± 3.0mm. There was a statistically significant correlation (R = 0.58) between the M-L length of the superior IS tendon relative to the M-L HH distance (P < .05) and the A-P HH distance (P < .05).

Conclusions

The superior M-L IS tendon length was significantly greater than the inferior M-L length. The M-L HH and the AP HH distances were significantly correlated to the M-L length of the superior portion of the IS tendon. These relationships may provide an estimation of the length of available IS tendon to help guide the management of Hill-Sachs lesions (HSLs).

Clinical Relevance

Knowledge of the available IS length can help optimize the management of HSLs following anterior shoulder dislocation. If IS tendon M-L length is less than HSL M-L length, then remplissage may result in capsulomyodesis rather than tenodesis. Placement of the superior anchor in a position that is as superior as possible within the HSL defect will maximize the opportunity for IS tenodesis.

[Rotator cuff tear : Indications and pathology-specific reconstructive procedures]

Rotator cuff (RC) tears comprise a broad spectrum of lesions ranging from partial to full thickness tears of a single tendon and massive cuff tears. Both glenohumeral trauma as well as degenerative processes can result in tearing of the RC. Treatment therefore requires a meticulous diagnosis as well as a differentiated approach by careful consideration of morphological and patient-specific factors. The pathogenesis, tear morphology, clinical symptoms and functional demands of the patient determine the therapeutic approach. Despite pathological and individual patient-related factors, early surgical repair is generally recommended for traumatic RC tears in young patients and in patients with high functional demands due to the high risk of tear progression. The results of RC repair are negatively correlated with the size of the lesion, the number of tendons involved, the degree of tendon retraction, muscular alteration and patient age. This article provides an overview of the various pathogenesis, indications and surgical repair of RC tears with respect to modern pathology-specific reconstructive procedures.

A case series of recurrent myotendinous rotator cuff tears repaired and augmented with dermal allograft: clinical outcomes at two years

When rotator cuff tears occur after a primary repair at the footprint, they often fail medially at the myotendinous junction, also called type II tears. These are difficult tears to treat, and little research has been published on how to address tears at the myotendinous junction and the clinical outcomes of the revised repairs. The purpose of this study is to evaluate the outcomes of type II rotator cuff tears repaired with a dermal allograft augmentation.

MATERIALS AND METHODS

We conducted a retrospective chart review of 9 patients with a type II rotator cuff tear medially at the myotendinous junction, arthroscopically repaired and augmented with acellular dermal allograft by a single surgeon. Two-year follow-up was obtained to evaluate pain, function, range of motion, and structural integrity of the repair via ultrasound.

RESULTS

Of all 9 patients, the mean visual analog scale preoperatively was 5.1 (standard error, ±2.1). With 9 patients having 2-year follow-up, the mean visual analog scale score continued to improve to 1.9 (standard error, ±2.4). At 2 years, the mean American Shoulder and Elbow Surgeons based on 8 patients was 76.1, and the mean Short Form 36 for all 9 patients was 78.7. All 9 patients with 2-year follow-up had an intact repair on ultrasound read by a musculoskeletal fellowship-trained radiologist.

DISCUSSION

Based on the early outcome data, patient satisfaction scores, and intact repairs visualized on ultrasound at 2 years postoperatively, the use of acellular human dermal matrix augmentation appears to be an efficacious and worthwhile treatment option for patients with recurrent rotator cuff tears at the medial myotendinous junction.

Traumatic Isolated Myotendinous Rupture of the Teres Minor in a Young Athlete - A Unique Case Report

Introduction:

Functional role of teres minor (TM) is well known. To date, an isolated myotendinous rupture of the TM, without any lesion of the other cuff tendons, has never been reported in literature.

Case Report:

The patient was a 22-year-old soccer player who has presented with a direct shoulder traumatism that is causing persistent pain and impairment. Early appropriate imaging was done (magnetic resonance imaging [MRI] and arthro-computed tomography scan); it revealed an isolated tear of the TM at the myotendinous junction. Open surgical repair was performed through a posterior approach, within the 1st month after the injury. The patient was immobilized for 1 month in neutral rotation and then was allowed to begin the rehabilitation process. At the 2-year follow-up point, the patient had a pain-free and functional shoulder, allowing a return to full activities, including sport at the pre-injury level. MRI confirmed that the muscle had healed, without atrophy or fatty infiltration.

Conclusion:

A TM myotendinous tear is very rare but might be under diagnosed. Early appropriate imaging is necessary. Surgical repair may be the preferable option in young and active patients and should be performed at the acute phase before muscular atrophy and fatty infiltration occur.

Supraspinatus Myotendinous Junction Injuries: MRI Findings and Prevalence

OBJECTIVE

The purpose of this study is to describe the MRI findings and evaluate the prevalence of supraspinatus myotendinous injuries.

MATERIALS AND METHODS

Among 1001 consecutive shoulders that underwent either conventional MRI or MR arthrography between January and December 2016, 843 shoulders were included. All MR images were retrospectively analyzed for identification and classification into the appropriate grade of acute or chronic rotator cuff myotendinous injuries. Other MRI findings, such as the presence of rotator cuff tendon insertional tears, and clinical information were also evaluated.

RESULTS

At MRI, 0.47% (4/843) of shoulders had supraspinatus myotendinous injuries involving the anterior muscular bundle exclusively. Chronic grade III (n = 2), acute grade III (n = 1), and acute grade II (n = 1) injuries were identified in three men and one woman (mean age, 44 years) with a clinical history of trauma (n = 2) or of progressive shoulder pain (n = 2). A concurrent supraspinatus insertional tendon tear with either partial (n = 1) or full (n = 1) thickness was present in half the cases. Loss of tension of the myotendinous junction in grade III myotendinous junction injuries led to severe atrophy and fatty infiltration of the anterior supraspinatus.

CONCLUSION

Supraspinatus myotendinous junction injuries are uncommon at MRI. These lesions invariably involve the anterior bundle of the supraspinatus muscle and may occur with a concomitant insertional tendon tear. High-grade chronic injuries lead to selective atrophy and fatty infiltration of the anterior supraspinatus muscle.

Arthroscopic Intramuscular Side-to-Side Repair of an Isolated Infraspinatus Tear

Intramuscular, full-thickness rotator cuff tears are uncommon and present a challenging clinical scenario for repair because traditional suture anchor or transosseous repair techniques are less feasible. The goal of repair is to achieve a tension-free reduction of both ends of the muscle to allow for adequate healing over time. Intramuscular tears of the infraspinatus specifically have rarely been reported. The clinical presentation of these patients can be challenging to interpret, and other causes of rotator cuff dysfunction, including compression to the suprascapular nerve, must be ruled out. In this Technical Note, we describe our technique for arthroscopic side-to-side suture repair of an isolated intramuscular infraspinatus tear.

Rotator Cuff Tears at the Musculotendinous Junction: Classification and Surgical Options for Repair and Reconstruction

Although uncommon, rotator cuff tears that occur medially at the musculotendinous junction can result from acute trauma, anatomic force imbalance, or medial row cuff failure following a previous rotator cuff repair. The quality of the torn muscle and tendon along with the length of the remnant tendon stump should be considered before deciding on the most appropriate repair technique. When muscle and tendon quality are sufficient, the tear can often be repaired directly to the remnant tendon stump and compressed onto the greater tuberosity. If the remnant tendon stump is degenerative, of insufficient length, or lacks tendon in which to place sutures, an allograft patch can be used to augment the repair. When the quality of the remaining muscle and tendon are poor or when the muscle is retracted too far medially and is nonmobile, a bridging technique such as superior capsule reconstruction is preferable. The purpose of this report is to (1) highlight that medial cuff failure can occur both primarily and after previous repair; (2) define and classify the 3 major tear patterns that are encountered, and (3) describe the authors' preferred techniques for medial cuff repair that specifically address each of the major tear patterns.

Classification of full-thickness rotator cuff lesions: a review

Rotator cuff lesions (RCL) have considerable variability in location, tear pattern, functional impairment, and repairability.

Historical classifications for differentiating these lesions have been based upon factors such as the size and shape of the tear, and the degree of atrophy and fatty infiltration. Additional recent descriptions include bipolar rotator cuff insufficiency, ‘Fosbury flop tears’, and musculotendinous lesions.

Recommended treatment is based on the location of the lesion, patient factors and associated pathology, and often includes personal experience and data from case series. Development of a more comprehensive classification which integrates historical and newer descriptions of RCLs may help to guide treatment further.

Cite this article: Lädermann A, Burkhart SS, Hoffmeyer P, et al. Classification of full thickness rotator cuff lesions: a review. EFORT Open Rev 2016;1:420-430. DOI: 10.1302/2058-5241.1.160005.

Delaminating infraspinatus tendon tears with differential retraction: imaging features and surgical relevance

OBJECTIVE

To describe infraspinatus tendon injuries with associated intramuscular edema in light of more recently elucidated anatomical knowledge.

MATERIAL AND METHODS

A retrospective review was performed to identify MRI cases with infraspinatus tendon injury accompanied by muscle edema. MR images were reviewed to evaluate the location of the injury, to assess the degree of tendon retraction, and to assess for muscular changes. Clinical and surgical data were reviewed when available.

RESULTS

Twenty-three patients were identified (13 males, 10 females, mean age of 52 years). MRI demonstrated infraspinatus muscle edema in all cases with variably retracted infraspinatus tendon fibers. Three patients (13 %) presented acutely after traumatic falls, 11 patients (48 %) presented after a minor trauma or recalled event, and 9 patients (39 %) presented with more chronic symptoms. Of the nine patients who underwent arthroscopic surgery, six patients (67 %) did not have an identifiable corresponding lesion, despite the findings described on the preoperative MRI. In these six cases, some superficial fibers of the transverse portion of the infraspinatus tendon remained intact on the MRI. Three patients (13 %) had follow-up MRI examinations with one progressing to severe muscle atrophy, one without progression of existing muscle atrophy, and one with no atrophy on the initial or subsequent evaluation. Eighteen of 23 patients had concomitant partial-thickness or full-thickness tears of the adjacent supraspinatus tendon.

CONCLUSION

Injuries of the infraspinatus tendon with resultant muscle edema and variable muscle atrophy may, in fact, represent delaminating type injuries with differential retraction of a layered tendon and may be missed on arthroscopy.

Intramuscular migration of calcium hydroxyapatite crystal deposits involving the rotator cuff tendons of the shoulder: report of 11 patients

OBJECTIVE

The intent of the study is to describe an unusual pattern of intramuscular migration of calcific deposits related to hydroxyapatite deposition disease (HADD) involving the rotator cuff, to illustrate the characteristic imaging features of this phenomenon, and to discuss the clinical significance of such migration.

MATERIALS AND METHODS

A series of cases of intramuscular accumulation of calcium hydroxyapatite crystals collected over a 7-year period at multiple hospitals within the same academic institution were retrospectively reviewed.

RESULTS

The patient group was composed of seven men and four women, ranging in age from 51 to 79 years, with a mean age of 63 years. All subjects presented with acute shoulder pain. The majority of subjects reported the spontaneous onset of the symptoms (64%), while others reported weight lifting (27%) and a fall on the arm (9%) as the mechanisms of injury. The right shoulder was affected in 73% of the subjects. The supraspinatus was the most commonly affected muscle (82%), followed by the infraspinatus muscle (36%).

CONCLUSIONS

Knowledge of the imaging features of intramuscular migration of hydroxyapatite deposits is important in order to avoid the erroneous diagnosis of other causes of muscle edema and inflammation such as myotendinous injury, myositis, subacute denervation, and neoplasm.

MRI findings of rotator cuff myotendinous junction injury

OBJECTIVE

The purpose of this article is to describe the MRI features of rotator cuff myotendinous junction injuries.

MATERIALS AND METHODS

We retrospectively identified MRI cases with myotendinous junction injury of the rotator cuff muscles and reviewed clinical, imaging, and surgical records. MR images were reviewed independently by two musculoskeletal radiologists to grade myotendinous junction injuries (strain, partial tear, or complete tear) and to assess for concurrent tendon tears (partial or full thickness) and bone changes (fracture or contusion).

RESULTS

The final study group comprised 16 subjects. The mean age was 38 years, with a majority of men (56%). The left shoulder was affected in 56% of subjects, with the dominant upper limb affected in 50%. The mean time between symptoms and MRI was 19 days. Subjects reported heavy lifting (19%), landing on the arm after a fall (19%), or prior shoulder therapeutic injection (25%). Myotendinous junction injuries affected the infraspinatus muscle (50%), followed by the supraspinatus (31%), subscapularis (25%), and teres minor (19%) muscles. About one fifth of subjects presented with more than one muscle affected, and 94% did not present with tears of the corresponding tendons. Most myotendinous junction injuries were strains (80%), followed by partial tears (20%). No complete tears were identified. There was no correlation between myotendinous junction injury and the presence of bone changes or the presence of tendon tears (p > 0.05).

CONCLUSION

Rotator cuff myotendinous junction injuries affect mostly the infra-spinatus and supraspinatus muscles, usually in a strain pattern and without tear of the corresponding tendon attachment.

Supraspinatus rupture at the musculotendinous junction in a young woman

The vast majority of rotator cuff tears occur within the tendon or as an avulsion from the greater tuberosity. Supraspinatus injury at the musculotendinous junction is a very uncommon event. We describe a case of supraspinatus rupture at the musculotendinous junction, with successful conservative treatment. It occurred in a 23-year-old woman, the youngest patient with this uncommon type of injury. To our knowledge, this is the first case of rupture of the supraspinatus muscle at the musculotendinous junction in a young woman and the second in a woman.

The aging athlete: part 2, "boomeritis" of the upper extremity

OBJECTIVE

The purpose of this review is to describe the upper extremity injuries that frequently accompany aging, the typical clinical presentations, and the differential diagnoses with an emphasis on the injury most likely encountered with each presentation.

CONCLUSION

Expectation of continued participation in exercise and sports activities by the baby boomer population has presented new challenges to the medical field. The concepts behind factors that predispose older athletes to certain pathologic conditions that affect the muscles, tendons, and bones of the upper extremity must be understood.

Supraspinatus rupture at the musclotendinous junction: an uncommonly recognized phenomenon

BACKGROUND

The majority of rotator cuff lesions involving the supraspinatus occur at or near the level of bone-tendon interface. We present a series of supraspinatus injuries at the musculotendinous junction.

METHODS

Between October 2002 and December 2009, we prospectively evaluated all patients presenting with an injury of the supraspinatus at the musculotendinous junction.

RESULTS

Five patients (1 female and 4 males) were identified. Three patients had a clear history of trauma. All patients presented acutely with pain and muscular edema on T2 magnetic resonance imaging (MRI) sequences. Lesions were characterized as stretch injuries in 2 cases and complete rupture at the level of the musculotendinous junction in 3 cases. Electrodiagnostic studies were normal in all cases. All patients were treated nonoperatively. On clinical and radiological examination at an average of 24 ± 10 months (range, 10-38), 1 patient had complete clinical and radiological resolution, 1 improved, and 3 who complained of loss of function demonstrated severe fatty infiltration on MRI.

CONCLUSION

Musculotendinous rupture of the supraspinatus is an unusual lesion of the rotator cuff. With incomplete injuries, recovery can be anticipated with nonsurgical management. However, in the case of a complete rupture with muscle retraction, nonoperative management leads to unsatisfactory outcomes.

Severe atrophy and fatty degeneration of the infraspinatus muscle due to isolated infraspinatus tendon tear

Atrophy of both the supraspinatus and infraspinatus muscles is usually caused by chronic rotator cuff tear, but may also derive from suprascapular nerve entrapment at the spinoglenoid notch. Isolated infraspinatus muscle atrophy is uncommon, and typically associates with suprascapular nerve entrapment occurring distal to the spinoglenoid notch. However, isolated atrophy of the infraspinatus muscle due to insertional tear of the infraspinatus tendon may also occur. We present a case of a 43-year-old male with isolated infraspinatus muscle atrophy and fatty degeneration following an isolated full-thickness infraspinatus tendon tear at the insertion site on the humerus. While it is important to rule out other causes of infraspinatus muscle atrophy, such as concomitant rotator cuff tendon/muscle pathology or suprascapular nerve palsy, we present this case to increase awareness of this uncommon clinical presentation and the potential implications for treatment.

Musculotendinous infraspinatus rupture and shoulder weakness

We report a patient with bilateral simultaneous onset of weakness of shoulder lateral rotation due to musculotendinous infraspinatus rupture that occurred after shoulder steroid injections. Disruption of the musculotendinous junction of the infraspinatus is a rare recently described entity. Electromyography is normal, and magnetic resonance image findings are characteristic.