The rotator interval and long head biceps tendon: anatomy, function, pathology, and magnetic resonance imaging

The rotator interval is an anatomically defined triangular area located between the coracoid process, the superior aspect of the subscapularis, and the anterior aspect of the supraspinatus. It is widely accepted that the rotator interval structures fulfill a role in biomechanics and pathology of the glenohumeral joint and long head biceps tendon. However, there is ongoing debate regarding the biomechanical details and the indications for treatment. A better understanding of rotator interval anatomy and function will lead to improved treatment of rotator interval abnormalities, and guide the indications for imaging and surgical intervention.

Sonography of partial-thickness tears of the distal triceps brachii tendon

OBJECTIVES

The purpose of this study was to retrospectively characterize the sonographic appearance of partial-thickness distal triceps brachii tendon tears.

METHODS

After Institutional Review Board approval, sonographic records were searched for patients who had an unequivocal partial-thickness triceps tendon tear at surgery or magnetic resonance imaging. Sonograms were retrospectively characterized for tendon discontinuity of the superficial or deep layers, tendon retraction, osseous fracture fragments, and joint effusion. Imaging findings were then compared with clinical, imaging, and surgical results.

RESULTS

Five patients had a partial-thickness distal triceps brachii tendon tear at surgery (n = 4) or magnetic resonance imaging (n = 1). All cases only involved the superficial tendon layer (combined long and lateral heads) with retraction of a fractured olecranon enthesophyte fragment. The deep tendon layer (medial head) was intact in all cases with no joint effusion.

CONCLUSIONS

Partial-thickness distal triceps brachii tendon tears have a characteristic appearance with selective superficial tendon retraction and olecranon enthesophyte avulsion fracture.

Usefulness of the twinkling artifact in identifying implanted mesh after inguinal hernia repair

OBJECTIVES

Implanted mesh for inguinal hernia repair is often difficult to visualize with gray scale sonography and may present without the knowledge of the sonographer. We sought to evaluate the utility of the twinkling artifact produced by inguinal mesh to assist in mesh identification.

METHODS

Two reviewers evaluated focused sonographic examinations of 44 inguinal regions, 24 of which had implanted inguinal mesh. The sonographic examinations consisted of static gray scale and color Doppler images with both linear and curvilinear array transducers. The presence of the twinkling artifact and visibility of the mesh were graded on a 4-point visibility scale.

RESULTS

Inguinal mesh was not easily identified on gray scale imaging using either the curvilinear array (P = .5) or linear array (P = .5) transducer. The mesh was definitely seen in 3 of 24 inguinal regions using the linear array transducer and 2 of 24 inguinal regions using the curvilinear array transducer. In 79% of inguinal regions with mesh, the twinkling artifact was produced with the curvilinear array transducer only. The artifact was not elicited when using the linear array transducer. With the use of the curvilinear array transducer and the presence of the twinkling artifact, there was a significant chance of correctly identifying the presence of mesh (P < .005) in the entire study group.

CONCLUSIONS

Standard gray scale imaging alone is not reliable when identifying inguinal mesh. The twinkling artifact was present in 79% of inguinal regions with mesh when evaluated with a low-frequency curvilinear array transducer.

The subscapularis: anatomy, injury, and imaging

The subscapularis is the largest and most powerful of the rotator cuff muscles and fulfills an important role in glenohumeral movement and stability. The spectrum and implications of subscapularis muscle or tendon injury differ from injury to other rotator cuff components because of its unique structure and function. Diagnosing subscapularis injury is clinically difficult and assessment of subscapularis integrity may be limited during arthroscopy or open surgery. Diagnostic imaging plays an important part in diagnosing and evaluating the extent of subscapularis injury. The radiologist should be aware of the anatomy of the subscapularis, the variations in muscle or tendon injury, and the potential implications for treatment and prognosis.

MRI interpretation proficiency of musculoskeletal fellows in training

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate the magnetic resonance imaging (MRI) interpretation proficiency of musculoskeletal fellows in training.

MATERIALS AND METHODS

Between July 2003 and June 2007, 14 musculoskeletal fellows were independently tested with 20 MRI studies of the knee and shoulder at four separate time points during their fellowship years. Trends in true-positive and false-positive interpretation results were evaluated. Fellows who completed their residencies at the fellowship institution (internal fellows) were compared with those from other residencies (external fellows).

RESULTS

There was a significant improvement in proficiency between the initial and final (9-month) evaluations (P < .0001). At the initial evaluation, there was a mean of 52.8% (41.7 of 79) true-positive results (range, 32-51); at 9 months, there was a mean of 71.0% (56.1 of 79; range, 40-72). The number of false-positive results also declined during this time period from a mean of 8.1 (range, 2-13) at initial evaluation to 4.7 (range, 2-8) at 9 months (P < .001). External fellows had more incorrect diagnoses initially but showed greater improvement than internal fellows at 9 months.

CONCLUSION

Fellows continued to improve their MRI interpretation skills throughout the first 9 months of their fellowships. External fellows were slightly less proficient at the start of their fellowships but slightly more proficient at 9 months compared to internal fellows.

Sonographic evaluation of Lisfranc ligament injuries

OBJECTIVE

This study characterized the sonographic appearances of Lisfranc injuries.

METHODS

Sonography reports (2000-2007) were searched for "Lisfranc," resulting in 10 patients. Sonographic images of affected and asymptomatic contralateral feet were reviewed, recording the thickness of the dorsal ligament between the first (medial) cuneiform (C1) and second metatarsal (M2) ligaments, distance between C1 and M2, and change in this distance with weight bearing, hyperemia, and fractures. Correlations were made to clinical, surgical, and other imaging findings.

RESULTS

In 5 asymptomatic feet, the dorsal C1-M2 ligament was 0.9 to 1.2 mm thick, and the C1-M2 distance was 0.5 to 1 mm. Of the symptomatic feet, 1 group (n=3) had normal sonographic findings (thickness, 0.9-1.1 mm; distance, 0.6-0.7 mm; all had normal radiographic findings and follow-up, and 1 had normal magnetic resonance imaging [MRI] findings). Another group (n=3) had abnormal hypoechogenicity and thickening of the dorsal C1-M2 ligament (1.4-2.3 mm), a normal C1-M2 distance (0.6-0.7 mm), and no widening with weight bearing (1 of 1), consistent with a ligament sprain (1 had normal computed tomographic [CT] findings, and all had uneventful follow-up). The third group (n=4) had nonvisualization of the dorsal C1-M2 ligament, an increased C1-M2 distance of 2.5 to 3.1 mm, and further widening with weight bearing (3 of 4) from Lisfranc ligament disruption (shown at surgery in 2, MRI in 1, and CT in 1).

CONCLUSIONS

Nonvisualization of the dorsal C1-M2 ligament and a C1-M2 distance of 2.5 mm or greater were indirect signs of a Lisfranc ligament tear. Dynamic evaluation with weight bearing showed widening of the space between C1 and M2.

Sonographic surface localization of subcutaneous foreign bodies and masses

We report a sonographic technique of skin marking of the projection of nonpalpable subcutaneous foreign bodies and masses using a paperclip. Localization and marking of the overlying skin assists in preoperative planning and further management.

Sonography of fat necrosis involving the extremity and torso with magnetic resonance imaging and histologic correlation

OBJECTIVE

The purpose of this study was to describe the sonographic appearance of pathologically proven isolated fat necrosis involving the extremities or torso with magnetic resonance imaging (MRI) correlation.

METHODS

A query of the Department of Pathology database at our institution for the diagnosis of fat necrosis resulted in 1539 cases. Review of the cases and medical records excluded cases without sonographic imaging, those involving the breast, and those within or adjacent to a primary process, including masses or prior surgery, which resulted in a total of 5 cases of primary fat necrosis, 2 of which were evaluated with MRI. Sonograms were reviewed by 2 musculoskeletal radiologists and characterized with regard to location, echogenicity, shadowing, posterior through-transmission, a hypoechoic rim or halo, definition of borders, homogeneity, a mass effect, and vascularity. The patient medical records, histologic results, and MRI findings were also reviewed.

RESULTS

Of the 5 cases of isolated fat necrosis, 2 involved the torso and 3 the lower extremities. On sonography, all were located in the subcutaneous fat; 2 were isoechoic; 3 were hyperechoic; 2 had a hypoechoic halo; none showed shadowing or posterior through-transmission; 2 were well defined; 3 were masslike; 4 were heterogeneous; and 2 showed increased flow on color or power Doppler imaging. Magnetic resonance imaging showed an intermediate signal and either diffuse or ring enhancement.

CONCLUSIONS

Isolated fat necrosis of the extremities and torso had 2 sonographic appearances, which included a well-defined isoechoic mass with a hypoechoic halo and a poorly defined hyperechoic region in the subcutaneous fat.

Sonography of Morel-Lavallee lesions

OBJECTIVE

The purpose of this series was to retrospectively characterize the sonographic appearance of posttraumatic Morel-Lavallée lesions.

METHODS

After Institutional Review Board approval was obtained, a search of the radiology information system database with correlation to medical records identified 21 posttraumatic fluid collections of the hip and thigh in 15 patients. Sonographic images were retrospectively reviewed by 1 author to characterize the echogenicity, homogeneity, shape, margins, location, compressibility, and vascularity of the fluid collection. Results were correlated with the age of the fluid collection and aspiration results where possible.

RESULTS

All fluid collections (21/21) were located between the deep fat and fascia, with a shape that was fusiform in 12 (60%) of 20, flat in 5 (25%), and lobular in 3 (15%) (shape not determined in 1 case). Regarding echogenicity, 15 (71%) of the 21 collections were hypoechoic, and 6 (29%) were anechoic; 13 (62%) were heterogeneous, and 8 (38%) were homogeneous. The lobular fluid collections were all less than 2 weeks of age, and the flat fluid collections were all greater than 6 months of age. All homogeneous fluid collections were greater than 8 months of age. There was no relationship between the age of a fluid collection and its echogenicity. Conclusions. Morel-Lavallée lesions had a variable appearance, being more homogeneous and flat or fusiform in shape with a well-defined margin as the lesions aged. All Morel-Lavallée lesions were hypoechoic or anechoic, compressible, and located between the deep fat and overlying fascia.

Abdominal wall hernia mesh repair: sonography of mesh and common complications

OBJECTIVE

The purposes of this study were (1) to review the sonographic in vitro and in vivo appearances of mesh for surgical repair of abdominal wall hernias, (2) to describe sonographic techniques and discuss the limitations of sonography in evaluation of mesh hernia repair, and (3) to illustrate common complications after mesh repair shown with sonography.

METHODS

We identified interesting cases from the musculoskeletal sonographic database as well as from the teaching files of the authors, with surgical or other cross-sectional imaging corroboration.

RESULTS

A compilation of the sonographic appearances of mesh used for anterior abdominal wall and inguinal hernia repair and complications diagnosable by sonography is presented.

CONCLUSIONS

Sonography can be effective for evaluation of mesh and complications after mesh repair of anterior abdominal wall and inguinal hernias.

Lisfranc joint displacement following sequential ligament sectioning

BACKGROUND

There are two primary radiographic patterns of Lisfranc instability, transverse and longitudinal. There is no single diagnostic method with which to consistently confirm the diagnosis of an unstable injury. Our purpose was to define which ligament disruptions produce these two injury patterns and to compare the utility of weight-bearing and stress radiographs for detecting each pattern of instability.

METHODS

Ten fresh-frozen cadaveric lower extremities were dissected to expose the dorsal aspect of the midfoot. Radiographic markers were placed at the base of the second metatarsal and the distal borders of the first and second cuneiforms. The specimens underwent sectioning of the interosseous first cuneiform-second metatarsal (Lisfranc) ligament and were then divided into two groups. The transverse group underwent sectioning of the plantar ligament between the first cuneiform and the second and third metatarsals at the plantar aspect of the second cuneiform-second metatarsal joint, whereas the longitudinal group underwent sectioning of the interosseous ligament between the first and second cuneiforms. Weight-bearing, adduction, and abduction stress radiographs were made before and after each ligament was sectioned. The radiographs were digitized, and displacement was recorded. Instability was defined as >or=2 mm of displacement.

RESULTS

Weight-bearing radiographs made after the Lisfranc (first cuneiform-second metatarsal) ligament alone was sectioned were diagnostic (showed instability) for one of ten specimens. Abduction stress radiographs were diagnostic for two of five specimens, and adduction stress radiographs were diagnostic for zero of five specimens. In the transverse group (sectioning of the plantar ligament between the first cuneiform and the second and third metatarsals), weight-bearing radiographs were diagnostic on the basis of first cuneiform-second metatarsal displacement for one of five specimens but were not diagnostic on the basis of second cuneiform-second metatarsal displacement for any of five specimens. Abduction stress radiographs were diagnostic on the basis of displacement of both the first cuneiform-second metatarsal and the second cuneiform-second metatarsal joints for five of five specimens. In the longitudinal group (sectioning of the interosseous ligament between the first and second cuneiforms), weight-bearing radiographs were diagnostic on the basis of first cuneiform-second metatarsal displacement for one of five specimens and were diagnostic on the basis of displacement between the first and second cuneiforms for one of five specimens. Adduction stress radiographs were diagnostic on the basis of first cuneiform-second metatarsal displacement for one of five specimens and were diagnostic on the basis of displacement between the first and second cuneiforms for four of five specimens.

CONCLUSIONS

Transverse instability required sectioning of both the interosseous first cuneiform-second metatarsal ligament and the plantar ligament between the first cuneiform and the second and third metatarsals. Longitudinal instability required sectioning of both the interosseous first cuneiform-second metatarsal ligament and the interosseous ligament between the first and second cuneiforms. Compared with weight-bearing radiographs, injury-specific manual stress radiographs showed qualitatively greater displacement when used to evaluate both patterns of instability.

Wagner-Meissner neurilemmoma of the right cheek

We report a very rare case of Wagner-Meissner neurilemmoma in the cheek of a 10-year-old boy. The tumor presented as a slowly growing soft tissue swelling. Magnetic resonance imaging disclosed a very infiltrative, 9-cm mass involving the subcutis and deep soft tissues of the right cheek. Microscopically, the tumor was unencapsulated and composed almost entirely of well-formed Wagner-Meissner corpuscles that formed confluent sheets, perivascular cuffs, and individual corpuscles percolating through adipose tissue. Compared with the 3 previous reports, which describe circumscribed, encapsulated tumors in adult patients, this case had distinctive clinicopathologic features never reported: presentation in a pediatric patient, location in the head and neck region, and an infiltrative growth pattern.

Clinical indications for digital imaging in dento-alveolar trauma. Part 1: traumatic injuries

Traumatized teeth present a clinical challenge with regard to their diagnosis, treatment plan, and prognosis. Recent developments in imaging systems have enabled clinicians to visualize structural changes effectively. Computed tomography, magnetic resonance imaging and cone beam computed tomography are among the most commonly used systems for dental and maxillofacial surgery. The purpose of this review is to describe the advantages and disadvantages of each technique and the clinical application for dento-alveolar trauma. Three clinical cases are described to illustrate the potential use of the NewTom 3G for diagnosis and treatment plan of dento-alveolar traumatic injuries.

Characteristic Locations of Inguinal Region and Anterior Abdominal Wall Hernias: Sonographic Appearances and Identification of Clinical Pitfalls

OBJECTIVE

The purpose of this article is to show the typical locations of anterior abdominal wall and inguinal region hernias and to illustrate their sonographic appearances and describe pitfalls in clinical diagnosis of hernias that may be resolved with sonography.

CONCLUSION

Awareness of the expected locations of anterior abdominal wall hernias and potential clinical pitfalls allows an accurate diagnosis of a hernia and helps in differentiating a hernia from other abnormalities.

Magnetic resonance imaging of the rotator cuff interval

The rotator cuff interval (RCI) is an important and anatomically complex region of the rotator cuff that is critically important to normal glenohumeral function. Recognition of common pathologies in this region on imaging examinations is especially important as injuries may be difficult to detect on clinical examination and even at arthroscopy. Familiarity with the magnetic resonance imaging appearance of the normal and abnormal RCI and the ability to convey findings to orthopedic and sports medicine referrers are essential to facilitate prompt creation of effective treatment plans.

US Appearance of the Rotator Cable with Histologic Correlation: Preliminary Results

PURPOSE

To characterize the ultrasonographic (US) appearance of the rotator cuff cable in asymptomatic shoulders and in cadaveric specimens, with histologic comparison for the latter.

MATERIALS AND METHODS

The cadaveric portion of this study was approved by the institution's Anatomical Donations Department. Institutional review board approval and informed consent were obtained from asymptomatic volunteers and clinical patients for the HIPAA-compliant portion of the study. Four fresh cadaveric shoulder specimens (two male subjects, 40 and 50 years old) were dissected, assessed for the presence of the rotator cable, and imaged with 12-MHz US. Histologic slides (hematoxylin-eosin stain) from three resected rotator cuff tendons were inspected for fibers in the expected location and orientation of the rotator cuff cable. The shoulders in 17 asymptomatic volunteers (seven men, two women; age range, 27-66 years; mean, 41 years) and contralateral asymptomatic shoulders in 10 patients (six men, four women; age range, 24-78 years; mean, 49 years) were scanned and evaluated for the presence and appearance of the rotator cable.

RESULTS

The rotator cable was identified at gross dissection. Histologic examination and US of the cadaveric shoulders demonstrated an articular-sided fibrillar structure perpendicular to the rotator cuff tendon (average thickness and width, 1.2 mm and 4.5 mm, respectively). US of asymptomatic shoulders depicted a similar fibrillar structure in three (11%) shoulders up to 1.1-1.5 cm medial to the greater tuberosity (average thickness and width, 1.2 mm and 4.5 mm respectively).

CONCLUSION

The rotator cable can be depicted with US.

Classification of common acetabular fractures: radiographic and CT appearances

OBJECTIVE

Accurate characterization of acetabular fractures can be difficult because of the complex acetabular anatomy and the many fracture patterns. In this article, the five most common acetabular fractures are reviewed: both-column, T-shaped, transverse, transverse with posterior wall, and isolated posterior wall. Fracture patterns on radiography are correlated with CT, including multiplanar reconstruction and 3D surface rendering.

CONCLUSION

In the evaluation of the five most common acetabular fractures, assessment of the obturator ring, followed by the iliopectineal and ilioischial lines and iliac wing, for fracture allows accurate classification. CT is helpful in understanding the various fracture patterns.

Sonography of Inguinal Region Hernias

OBJECTIVE

The purpose of this article is to describe the anatomy of the inguinal region in a way that is useful for sonographic diagnosis of inguinal region hernias, and to illustrate the sonographic appearance of this anatomy. We show sonographic techniques for evaluating inguinal, femoral, and spigelian hernias and include surgically proven examples.

CONCLUSION

Understanding healthy inguinal anatomy is essential for diagnosing inguinal region hernias. Sonography can diagnose and differentiate between various inguinal region hernias.

MR Imaging of Rotator Cuff Injury: What the Clinician Needs to Know

The rotator cuff muscles generate torque forces to move the humerus while acting in concord to produce balanced compressive forces to stabilize the glenohumeral joint. Thus, rotator cuff tears are often associated with loss of shoulder strength and stability, which are crucial for optimal shoulder function. The dimensions and extent of rotator cuff tears, the condition of the involved tendon, tear morphologic features, involvement of the subscapularis and infraspinatus tendons or of contiguous structures (eg, rotator interval, long head of the biceps brachii tendon, specific cuff tendons), and evidence of muscle atrophy may all have implications for rotator cuff treatment and prognosis. Magnetic resonance imaging can demonstrate the extent and configuration of rotator cuff abnormalities, suggest mechanical imbalance within the cuff, and document abnormalities of the cuff muscles and adjacent structures. A thorough understanding of the anatomy and function of the rotator cuff and of the consequences of rotator cuff disorders is essential for optimal treatment planning and prognostic accuracy. Identifying the disorder, understanding the potential clinical consequences, and reporting all relevant findings at rotator cuff imaging are also essential.

Sonographic diagnosis of an arterioarticular fistula following knee arthrocentesis

An arterioarticular fistula is an unusual complication of knee arthrocentesis. We describe the sonographic findings immediately following a failed clinical attempt at knee arthrocentesis that resulted in an arterioarticular fistula. Spectral Doppler analysis confirmed the jet of blood into the hemarthrosis. Knowledge of anatomy and application of standard technique is necessary to minimize the complications of arthrocentesis.

Golf and Racquet Sports Injuries

There are specific injuries that are common in golf and racquet sports. These abnormalities have a predilection for specific structures as well and can be divided into two categories on the basis of etiology as either chronic repetitive injury or acute trauma. With golf injuries, upper extremity abnormalities prevail and include rotator cuff disease, epicondylitis, wrist tenosynovitis, and hamate hook fracture. Thoracolumbar spine pain can also occur. The order of frequency of these ailments is different for professional and recreational athletes. With racquet injuries, as in tennis, lower extremity injuries are more common and include medial gastrocnemius and Achilles tendon abnormalities, although shoulder, elbow, and wrist abnormalities may also occur. Knowledge of the biomechanics behind each sport is also helpful in understanding the pathophysiology of injury and in part explains the findings seen at imaging.