Imaging of Osteoarthritis of the Hip.

Hip osteoarthritis (OA) is a disease process that impacts the aging population. OA of the hip is the result of degeneration of the articular cartilage, underlying bone and soft tissue structures. Radiography is the first-line modality for imaging OA. Radiographic assessment includes imaging features of joint space narrowing, sclerosis, osteophytes, and bony deformities. CT can provide detailed evaluation of the hip with multiplanar reformats. MRI can assess bone marrow signal, articular cartilage damage, and labral abnormalities. Other disease process may appear similar or present concurrently with OA, such as osteonecrosis, rapidly progressive arthritis, and inflammatory and infectious arthropathies.

Occult fracture propagation in patients with isolated greater trochanteric fractures: patterns and management.

OBJECTIVE: To demonstrate the degrees of occult intertrochanteric extension on MRI in patients with a greater trochanteric fracture on radiography or computer tomography (CT) and whether these patients undergo conservative or surgical management with hardware. MATERIALS AND METHODS: Retrospective review was performed of 146 patients (104 females, 42 males, ages 33-102) who had follow-up MRI after identification of a greater trochanteric fracture without intertrochanteric extension on radiography or CT. Extent of intertrochanteric extension was recorded. Subsequently, EMR review was performed to see if patients underwent surgery. Specific note was made of hardware type. Analysis was performed to determine if there is a correlation with fracture type and surgical management as well as fracture type and age and gender. RESULTS: Nineteen patients had horizontal greater trochanter fractures without intertrochanteric extension; none underwent surgery. Seventeen patients had a vertical fracture along the lateral femoral cortex; one underwent surgery. Thirty-three patients had a fracture with intertrochanteric extension less than 50% in the mid coronal plane; 21 underwent surgery. Forty patients had intertrochanteric extension greater than 50% in the midcoronal plane not contacting the medial cortex; 28 underwent surgery. Thirty-seven patients had fractures contacting the medial cortex; 28 underwent surgery. There was significant difference with fractures extending 50% or greater of the midline of the intertrochanteric region undergoing surgical management compared with fractures less than 50% (p < 0.0001). CONCLUSION: MRI identifies the presence and extent of occult intertrochanteric fractures in patients with greater trochanteric fractures. Description of intertrochanteric fractures on MRI helps determine the patient's treatment course and influence surgical decisions.

Cadaveric Study of the Safety and Device Functionality of Magnetically Controlled Growing Rods After Exposure to Magnetic Resonance Imaging.

STUDY DESIGN: Cadaveric study. OBJECTIVE: To establish the safety and efficacy of magnetically controlled growing rods (MCGRs) after magnetic resonance imaging (MRI) exposure. SUMMARY OF BACKGROUND DATA: MCGRs are new and promising devices for the treatment of early-onset scoliosis (EOS). A significant percentage of EOS patients have concurrent spinal abnormalities that need to be monitored with MRI. There are major concerns of the MRI compatibility of MCGRs because of the reliance of the lengthening mechanism on strongly ferromagnetic actuators. METHODS: Six fresh-frozen adult cadaveric torsos were used. After thawing, MRI was performed four times each: baseline, after implantation of T2-T3 thoracic rib hooks and L5-S1 pedicle screws, and twice after MCGR implantation. Dual MCGRs were implanted in varying configurations and connected at each end with cross connectors, creating a closed circuit to maximize MRI-induced heating. Temperature measurements and tissue biopsies were obtained to evaluate thermal injury. MCGRs were tested for changes to structural integrity and functionality. MRI images obtained before and after MCGR implantation were evaluated. RESULTS: Average temperatures increased incrementally by 1.1°C, 1.3°C, and 0.5°C after each subsequent scan, consistent with control site temperature increases of 1.1°C, 0.8°C, and 0.4°C. Greatest cumulative temperature change of +3.6°C was observed adjacent to the right-sided actuator, which is below the 6°C threshold cited in literature for clinically detectable thermal injury. Histologic analysis revealed no signs of heat-induced injury. All MCGR actuators continued to function properly according to the manufacturer's specifications and maintained structural integrity. Significant imaging artifacts were observed, with the greatest amount when dual MCGRs were implanted in standard/offset configuration. CONCLUSIONS: We demonstrate minimal MRI-induced temperature change, no observable thermal tissue injury, preservation of MCGR-lengthening functionality, and no structural damage to MCGRs after multiple MRI scans. Expectedly, the ferromagnetic actuators produced substantial MR imaging artifacts. LEVEL OF EVIDENCE: Level V.

Postoperative Imaging of the Knee: Meniscus, Cartilage, and Ligaments.

This article reviews the normal and abnormal postoperative imaging appearance of frequently performed surgical procedures of the meniscus, articular cartilage, and ligaments. Imaging algorithms and protocols are discussed with particular attention to MR imaging techniques. Attention is paid to surgical procedures and the expected postoperative appearance as well to commonly identified recurrent and residual disorders and surgical complications.

Imaging of shoulder instability.

The glenohumeral joint is an inherently unstable articulation and consequently the most frequently subluxed and frankly dislocated joint in the body. Shoulder instability can be uni- or multidirectional related to acute or repetitive stress and is occasionally secondary to congenital or developmental abnormalities such as a lax joint capsule or glenoid dysplasia. The clinical diagnosis of instability can be difficult, and knowledge of the imaging findings of anterior, posterior, multidirectional, and microinstability is essential to guide the correct treatment of these patients. This requires the appropriate use of many different imaging modalities as well as specific positioning and directed protocols. This review article explains the clinical scenarios associated with shoulder instability and how they relate to the choice of imaging techniques. The imaging findings of the most common soft tissue and osseous pathology are reviewed and explained with specific attention to anterior and posterior instability.

US of the elbow: indications, technique, normal anatomy, and pathologic conditions.

The elbow, a synovial hinge joint, is a common site of disease. Ultrasonography (US) has become an important imaging modality for evaluating pathologic conditions of the elbow. This powerful imaging tool has the advantages of outstanding spatial resolution, clinical correlation with direct patient interaction, dynamic assessment of disease, and the ability to guide interventions. Unlike most other imaging modalities, US allows the contralateral elbow to be imaged simultaneously, providing an internal control and comparison with normal anatomy. A useful approach to US evaluation of the elbow is to divide it into four compartments: anterior, lateral, medial, and posterior. US of the elbow has varied clinical applications, including evaluation and treatment of lateral and medial epicondylitis, imaging of biceps and triceps musculotendinous injuries, evaluation of ulnar collateral ligament laxity, diagnosis of joint effusions and intraarticular bodies, and evaluation of peripheral nerves for neuropathy and subluxation. US can also be used to evaluate soft-tissue masses about the elbow. Knowledge of the normal US anatomy of the elbow, familiarity with the technique of elbow US, and awareness of the US appearances of common pathologic conditions of the elbow along with their potential treatment options will optimize radiologists' diagnostic assessment and improve patient care. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.334125059/-/DC1.

Shoulder MR imaging normal variants and imaging artifacts.

The appearance of osseous, labral, hyaline cartilage, ligament, muscle, and tendon variants and pitfalls are discussed with attention to the keys to distinguishing each of the findings from pathologic lesions of the shoulder.

Epicondylitis: pathogenesis, imaging, and treatment.

Epicondylitis commonly affects the elbow medially or laterally, typically in the 4th or 5th decade of life and without predilection with regard to sex. Epicondylitis is an inflammatory process that may be more accurately described as tendinosis. In the lateral epicondylar region, this process affects the common extensor tendon; in the medial epicondylar region, the common flexor tendon is affected. The condition is widely believed to originate from repetitive overuse with resultant microtearing and progressive degeneration due to an immature reparative response. Advances in understanding of the anatomy and pathophysiology of epicondylitis have shaped current treatment practices. Conservative measures are undertaken initially, because symptoms in most patients improve with time and rest. Those who fail to respond to conservative therapy are considered for surgical treatment. When surgery is contemplated, magnetic resonance imaging or ultrasonography is useful for evaluating the extent of disease, detecting associated pathologic processes, excluding other primary sources of elbow pain, and planning the surgical approach. Familiarity with the normal anatomy, the pathophysiology of epicondylitis and its mimics, and diagnostic imaging techniques and findings allows more accurate diagnosis and helps establish an appropriate treatment plan.

MR imaging of delamination tears of the rotator cuff tendons.

OBJECTIVE: The objective was to describe the imaging appearances and location of delamination tears of the rotator cuff tendons on non-contrast conventional MR imaging. SUBJECTS AND METHODS: This study was reviewed and approved by our Institutional Review Board. The reports of 548 consecutive MR examinations of the shoulder were reviewed, looking for mention or description of delamination tears of the rotator cuff. The images of the identified cases were then reviewed by two radiologists to confirm the findings. Correlation with surgical and arthroscopic information was then performed. Delamination tears were defined as horizontal retraction of either the bursal or articular surface of the tendon, manifest as thickening of the torn retracted edge, and/or interstitial splitting of the tendon, manifest as fluid-like high signal intensity on fat-suppressed T2-weighted oblique coronal images. RESULTS: Fourteen cases of delamination tears were identified in 13 patients. Ten of the cases involved the supraspinatus tendon, all with articular surface involvement. Nine of these supraspinatus cases were isolated tears and one occurred as part of a full thickness tear. All 10 of these supraspinatus cases showed medial retraction of the articular surface of the tendon, with thickening of the retracted edge, and 5 of the 10 had a demonstrable horizontal cleft in the interstitium. Four cases involved the subscapularis tendon, with articular surface disruption in three and pure interstitial delamination in one. Medial subluxation of the tendon of the long head of the biceps was present in all four cases. No delamination tears occurred on the bursal surface. Only three of the 14 shoulders underwent surgical repair with one confirmation of supraspinatus delamination, one confirmation of a subscapularis tear that had become a full thickness tear 10 months after initial imaging and another interstitial subscapularis delamination that was not identified arthroscopically. CONCLUSION: Delamination tears occur most often in the supraspinatus tendon, and in our series always involved the articular surface of the tendon. Only half of these tears have a visible cleavage plane in the interstitium, but this cleavage plane is not necessary for diagnosis if the torn edge is retracted.