J. Bruce Kneeland

MR imaging of muscle and tendon injury

The nature and MRI appearance of injuries to the muscle including delayed onset muscle soreness, muscle contusion, muscle strain, and compartment syndromes are described and examples shown. The nature of degenerative disease of tendon (tendinosis) is discussed and representative examples of the MRI appearance of various stages are illustrated. The role of MR in the clinical management of these disorders is discussed where appropriate.

Imaging of athletic injuries to the ankle and foot.

Conventional radiographs in conjunction with clinical examination remains the primary method for evaluating the acute athletic injury. In most cases, suspected acute tendon and ligament injuries are initially treated based on physical examination. Magnetic resonance (MR) imaging, with its multiplanar capability and superb soft tissue contrast, is quickly becoming the method of choice for evaluating chronic foot and ankle pain and further defining the extent of tendon and ligament injuries. This article reviews the common acute and chronic (overuse) foot and ankle athletic injuries with an emphasis on imaging characteristics.

Muscle impingement: MR imaging of a painful complication of osteochondromas

Abstractu2002The purpose of this study was to describe the magnetic resonance (MR) appearance of a newly recognized complication of osteochondromas. Two patients presented with pain and swelling over known osteochondromas. Plain radiographic studies were unrevealing. MR examinations were obtained to characterize the exostoses further and evaluate areas of palpable fullness. Increased signal was present in the muscles on T2-weighted images, which correlated with physical findings and was believed to represent muscle injury due to the osteochondroma. Pain and fullness may result from a number of osteochondroma-related complications, the most worrisome of which is malignant degeneration. Muscular impingement and injury should be considered in the differential diagnosis of pain and swelling in the region of an exostosis. MR imaging allows distinction of this entity, which may be radiographically occult and confused clinically with fracture, bursitis, or malignant degeneration.

Case report 822

Fig. 1. A Coronal proton density image (TR 2500/TE 20) through the proximal end of the right fibula demonstrates a lcsion arising from the lateral mctaphysis, one centimeter distal to the level of the epiphyseal plate. B Coronal T-2 weighted image (TR 2500/TE 80) shows a well-defined high signal cartilaginous cap covering the lesion Fig. 2. Axial T-1 weighted image (TR 600/TE 20). The peroneal nerve itself is not identified with certainty on the image, This is not surprising, as the nerve was found to be thin and splayed at surgery. However, the sequelae of peroneal nerve entrapment are clearly demonstrated. All of the visualized muscles of the anterior and lateral compartments are small with evidence of fatty infiltration. The atrophied muscles themselves are low in signal intensity. As suggested by the EMG study, the peroneus longus and brevis arc involved to a lcsser extent than the anterior compartment muscles Clinical information

Hand injuries in adults

The radiologist plays an important role in the evaluation of hand injuries. Although the detection of fractures is important, recognition and delineation of soft tissue damage is equally vital. If only soft tissue injuries exist, plain film findings are often nonspecific. Nevertheless, they can give helpful clues in evaluating ligaments and tendons. It is especially important for the radiologist to be knowledgeable of these soft tissue injuries because, in an emergency room setting, the radiologist may be the physician most familiar with the spectrum of injuries and possible complications.

Trochlear inclination angles in normal and dysplastic knees.

Trochlear morphology impacts component position in patellofemoral arthroplasty. We devised a measurement of the trochlear inclination angle (TIA) and determined the average TIA in normal and dysplastic knees. Three hundred twenty-nine consecutive magnetic resonance imagings of normal and dysplastic knees were evaluated. The TIA was measured by 2 reviewers. The Student t test was used, and intraobserver reliability measurements were made. The mean TIA in normal and dysplastic knees was internally rotated 11.4° (range, 6°-20°) and 9.4° (range, 4°-15°), respectively. The mean TIA did not differ significantly by sex or age. Trochlear inclination angles in both normal and dysplastic knees tend toward internal rotation. Positioning a trochlear patellofemoral arthroplasty component flush with the articular surface of the native trochlea would result in internal rotation malposition.

Magnetic resonance imaging of the shoulder

The shoulder is now accessible to MRI owing to recent technical advances. The major advantages of this modality include its noninvasive nature, lack of ionizing radiation, excellent contrast and anatomic resolution, multiplanar imaging capability, and ability as a single imaging modality to evaluate simultaneously for a wide variety of pathologic processes. It is proving its utility particularly in the evaluation of the painful shoulder and the diagnosis of glenohumeral instability, rotator cuff impingement, tendinitis, and tear. We believe that with greater experience and large comparative studies, MRI will clearly demonstrate its superiority in evaluation of the shoulder and will almost entirely replace arthrography, as has occurred with the knee.

The Incidence of Pathology Detected by Magnetic Resonance Imaging of the Knee: Differences Based on the Specialty of the Requesting Physician

The usage patterns of magnetic resonance imaging (MRI) by orthopedic and nonorthopedic surgeons were studied. A sample consisting of the radiologist reports from all knee MRIs in a single year at our institution were reviewed. Studies to evaluate tumors or infections were excluded. Reports were classified as normal or demonstrating degenerative joint disease, meniscal tears, cruciate ligament pathology, collateral ligament pathology, focal chondral defects, chondromalacia patella, cysts, extensor mechanism dysfunction, intraosseous edema, or fractures. Six hundred eighteen reports were reviewed. The combined incidence of a normal study or one that found only degenerative joint disease was 45% for nonorthopedic surgeons and 27.6% for orthopedic surgeons (P<.00001). Given the higher incidence of normal findings in studies ordered by nonorthopedic surgeons, these physicians probably use MRI more for screening whereas orthopedic surgeons are more apt to use it for confirmation. Therefore, if clinical guidelines for using MRI are to be established, differences in use as a function of specialty must be acknowledged.

Magnetic resonance imaging of lower extremity injuries.

T HE ACCURATE diagnosis and treatment of lower-extremity trauma requires a synthesis of clinical and imaging data. Knowledge of the mechanism of injury coupled with a thorough physical examination is indispensable in predicting the likely abnormality and expected sequela and in determining a tailored imaging approach to the patient. Conventional radiographs often suffice for diagnosis: however, at times, advanced imaging techniques are necessary to evaluate the extent of injury and determine the treatment options. Magnetic resonance imaging (MRI) is a widely available, noninvasive technique ideally suited to this task. Its multiplanar capability and highcontrast rendition result in an unparalleled depiction of the osseous and soft-tissue structures. The exquisite sensitivity of MRI for abnormalities within cancellous bone allows detection of symptomatic, previously occult injuries. With the continued evolution of MRI hardware and software, the list of musculoskeletal applications grows daily. This review will highlight the MRI appearance of commonly encountered lower extremity injuries. It will also address several technical considerations for successful imaging of lowerextremity trauma.

Magnetic resonance imaging of theshoulder: Rotator cuff disease and glenohumeral instability

Abstract Magnetic resonance imaging (MRI) has emerged as a powerful tool for the noninvasive evaluation of the musculoskeletal system. The use of MRI for the evaluation of disorders of the shoulder, however, remains more controversial than its use for the study of the knee. MRI has been shown by numerous investigators to be an accurate technique for confirming the presence of rotator cuff tears, determining their size, determining the presence of atrophy of the cuff muscles, and detecting the presence of different causes of cuff impingement. The use of MRI for the evaluation of glenohumeral instability is more problematic. In the presence of a large amount of joint fluid, MRI is reasonably accurate for the depiction of anatomic abnormalities associated with instability. In the absence of effusion, MRI is relatively inaccurate. For these cases MR arthrography is probably necessary to confirm the diagnosis.