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Biomedical subjects

A G Bergman

Publications and source records attributed to A G Bergman.

At least 19 recordsLinked to original sources
PubMed2001

Dynamic MR imaging and stress testing in glenohumeral instability: comparison with normal shoulders and clinical/surgical findings.

Our objectives were to test the hypotheses that: 1) during shoulder motion, glenohumeral alignment differs between asymptomatic shoulders and those with symptomatic instability; 2) during magnetic resonance (MR)-monitored physical exam or stress testing, glenohumeral alignment differs between asymptomatic shoulders and those with instability; and 3) glenohumeral translation during MR stress testing correlates with findings of shoulder instability by clinical exam and exam under anesthesia (EUA). Using an open-configuration 0.5 T MR imaging (MRI) system, we studied symptomatic shoulders in 11 subjects and compared them to their contralateral asymptomatic shoulders. Each shoulder was studied during abduction/adduction and internal/external rotation to determine the humeral head position on the glenoid. An examiner also performed the MR stress test on each shoulder by applying manual force on the humeral head during imaging. All shoulders were assigned an instability grade from the MR stress test, and this grade was correlated with: 1) clinical exam grade assigned during preoperative assessment by an orthopedic surgeon and 2) intraoperative instability grade by EUA immediately preceding arthroscopy. With dynamic abduction and internal/external rotation, the humeral head remained centered on the glenoid in 9 of 11 shoulders, but in two subjects there were dramatic demonstrations of subluxation. With stress testing, a trend toward more joint laxity was demonstrated in symptomatic than in asymptomatic joints (P = 0.11). MR grading of instability correlated directly with clinical grading in six cases and underestimated the degree of instability relative to clinical exam in the other cases. MR instability grading systematically underestimated instability compared with EUA in 7 of the 10 cases that underwent surgical repair. We concluded that dynamic MR evaluation of glenohumeral alignment did not demonstrate abnormalities in symptomatic shoulders in 8 of 10 patients, whereas 2 patients showed dramatic findings of subluxation. Manual stress testing during dynamic MR examination showed a strong correlation with clinical instability grading. Dynamic shoulder MR examination during stress testing could, with further validation, become a useful adjunct to shoulder instability evaluations. J. Magn. Reson. Imaging 2001;13:748-756.

Adolescent↗
PubMed2000

MR imaging of cyclops lesions.

OBJECTIVE: Localized anterior fibrosis (cyclops lesion) is a known cause of extension loss of the knee after anterior cruciate ligament (ACL) reconstruction. We describe MR imaging as a noninvasive diagnostic tool to examine cyclops lesions. SUBJECTS AND METHODS: Thirty-three MR studies of 31 patients with residual persistent extension loss after ACL reconstruction using patellar tendon autograft were reviewed and compared with results of second arthroscopy. We used MR imaging to describe the ACL graft signal intensity and course, tibial and femoral tunnel placement. quantitative measurements of notch size and shape, and the presence or absence of cyclops lesions. When a cyclops lesion was revealed on MR imaging, the signal-intensity characteristics, location, and size were documented. Preoperative MR imaging findings were then correlated with findings at arthroscopy. RESULTS: The sensitivity, specificity, and accuracy of revealing a cyclops lesion on MR imaging were 85.0%, 84.6%, and 84.8%, respectively. We found no statistically significant differences in the size of intercondylar notches for patients with and patients without cyclops lesions. CONCLUSION: MR imaging was sensitive, specific, and accurate in revealing cyclops lesions in a subgroup of patients with extension loss after ACL reconstruction.

Adolescent↗
PubMed1999

Coincident development of sesamoid bones and clues to their evolution.

Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity. In this article we review the literature on sesamoids and explore the question of genetic control of sesamoid development. Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella (in the lateral gastrocnemius tendon of the knee) and os peroneum (in the peroneus longus tendon of the foot) are related within individuals (P < 0.01). This finding suggests that the tendency to form sesamoids may be linked to intrinsic genetic factors. Evolutionary character analyses suggest that the formation of these sesamoids in humans may be a consequence of phylogeny. These observations indicate that variations of intrinsic factors may interact with extrinsic mechanobiological factors to influence sesamoid development and evolution.

Adult↗
PubMed1999

Joint motion in an open MR unit using MR tracking.

A system for active scan plane guidance during kinematic magnetic resonance (MR) examination of joint motion was developed utilizing an external tracking coil and MR tracking software. In a phantom study and during upright, weight-bearing, physiologic knee flexion, the external tracking coil maintained the scan plane through desired structures. Thus, MR tracking provides a robust method to guide the scan plane during MR imaging of active joint motion.

Biomechanical Phenomena↗
PubMed1999

Glenohumeral relationships during physiologic shoulder motion and stress testing: initial experience with open MR imaging and active imaging-plane registration.

PURPOSE: To test the hypotheses that open dynamic magnetic resonance (MR) imaging can (a) be used to evaluate and define normal shoulder motion in active joint motion and muscle contraction and (b) be used in conjunction with physical examination. MATERIALS AND METHODS: With an open-configuration, 0.5-T MR imaging system and active image-plane tracking, 10 shoulders were studied in five asymptomatic subjects to establish normal patterns of glenohumeral motion during abduction and adduction and internal and external rotation. Preliminary studies of physical examination during MR imaging, in which a physician examiner applied mechanical force to the humeral head, were also performed. RESULTS: During abduction and adduction and internal and external rotation maneuvers with active subjects muscle contraction, the humeral head remained precisely centered on the glenoid fossa in all asymptomatic subjects, which is in agreement with findings of previous radiographic studies. Application of force to the humeral head by an examiner was associated with as much as 6 mm of anterior translation and 13 mm of posterior translation. CONCLUSION: Dynamic MR imaging of the glenohumeral joint is possible over a wide range of physiologic motion in vertically open systems. Use of an MR tracking coil enabled accurate tracking of the anatomy of interest. These preliminary measurements of normal glenohumeral motion patterns begin to establish normal ranges of motion and constitute a necessary first step in characterizing pathologic motion in patients with common clinical problems such as instability and impingement.

Adult↗
PubMed1998

Shoulder MRI after impingement test injection.

OBJECTIVE: To determine how long injected fluid from an impingement test remains in the bursa or adjacent soft tissues after an injection. DESIGN AND PATIENTS: Six patients prospectively underwent MRI of the shoulder immediately before and after an impingement test injection, and at 3 days, 2 weeks and 4 weeks later. MR images were evaluated and graded for fluid distribution within the bursa and adjacent soft tissues. The rotator cuff was evaluated for signal abnormalities related to the injection. RESULTS AND CONCLUSION: Three days after the injection, the soft tissue fluid had returned to pre-injection levels or less in five of the six patients. No patients showed rotator cuff signal abnormalities related to the impingement test injection. We recommend a delay of 3 days before a shoulder MR examination after an injection has been performed, to avoid misinterpretations.

Adult↗
PubMed1998

Magnetic resonance imaging of knee cartilage repair.

Cartilage injury resulting in osteoarthritis is a frequent cause of disability in young people. Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies for cartilage injury and degeneration.

Cartilage, Articular↗
PubMed1997

[Stress fractures in athletes].

Stress fractures are one of the most common overuse injuries seen in athletes, accounting for up to 20% of all injuries presented to sports medicine clinics. Runners are particularly prone to these injuries, however, it is difficult to predict injury as there is usually a critical interplay between the athlete's biomechanical predisposition, training methods, and other factors such as diet, and muscle strength and flexibility. This article will discuss the key clinical findings for the majority of stress fractures encountered in a sports medicine practice. A classification scheme will also be described that will allow the clinician to make appropriate treatment decisions based on the degree of risk for each injury.

Athletic Injuries↗
PubMed1997

Meniscal tears of the knee: accuracy of detection with fast spin-echo MR imaging and arthroscopic correlation in 293 patients.

PURPOSE: To evaluate the accuracy of a magnetic resonance (MR) imaging strategy that uses primarily fast spin-echo (SE) sequences for the diagnosis of meniscal tears. MATERIALS AND METHODS: The original clinical interpretations of MR images in 293 patients who underwent imaging for suspected internal derangement of a knee joint were correlated with results from subsequent arthroscopy. MR examination included a double-echo fast SE sequence as the only imaging in the sagittal plane. RESULTS: The sensitivity and specificity for 143 confirmed tears of the medial meniscus were 89% and 84%, respectively, while the values for 96 confirmed tears of the lateral meniscus were 72% and 93%. These values are within the ranges of values recently reported for imaging strategies relying predominantly on conventional SE sequences. CONCLUSION: Fast SE imaging of the knee can be an alternative to conventional SE imaging for the detection of meniscal tears.

Adolescent↗
PubMed1997

Rotator cuff impingement. Pathogenesis, MR imaging characteristics, and early dynamic MR results.

Shoulder impingement can be diagnosed based on clinical findings, but clinical staging of its severity, which may range from reversible edema and hemorrhage to a complete rotator cuff tear, is often not possible. MR imaging allows direct examination of the thickness, signal characteristics, and continuity of the rotator cuff. Furthermore, MR imaging can be used not only to determine the status of the cuff, but also to detect pathology involving surrounding structures and to identify anatomic variations that may contribute to the impingement. Rapid MR imaging during active unguided shoulder motion will likely further increase our understanding of the biomechanics of the shoulder at different stages of impingement, and may shed further light on the pathogenesis of this disorder.

Adult↗
PubMed1995

MR imaging of ulnar impaction.

The ulnar impaction syndrome of the wrist is a well-recognized clinical entity, usually showing distinct radiographic features including a positive ulnar variance and degenerative subchondral changes of the distal ulna, proximal lunate, and proximal triquetrum. Confirmation of the clinical and plain film findings with advanced imaging is often necessary to exclude other entities with a similar clinical presentation. Although arthrography and bone scintigraphy are helpful in this work-up, magnetic resonance imaging (MRI) appears to be both a sensitive and a specific means of evaluation. The imaging studies in four patients with clinically and surgically diagnosed ulnar impaction are described, with emphasis on MRI findings. MRI appears to be the modality of choice in the evaluation of patients with suspected ulnolunate impingement.

Adult↗
PubMed1995

Localization of specific joint causing hindfoot pain: value of injecting local anesthetics into individual joints during arthrography.

OBJECTIVE: The purpose of this study was to evaluate the utility of selective injection of local anesthetic into hindfoot articulations for localizing the source of posttraumatic pain and to compare clinical response with the severity of degenerative change in the various articulations evident on plain radiographs or CT scans. SUBJECTS AND METHODS: Anesthetic arthrography was performed in 18 patients with posttraumatic hindfoot pain. In all, 32 joints were assessed: 15 talocalcaneonavicular, 11 subtalar, five ankle, and one calcaneocuboid. Following intraarticular injection of a mixture of equal amounts of meglumine diatrizoate 60%, lidocaine 1%, and bupivacaine 0.25%, patients were asked to grade the degree of pain relief they experienced on a scale from 0% to 100%. The degree of degenerative changes seen on preliminary radiographs and CT scans was graded blindly and retrospectively by an experienced musculoskeletal radiologist using a 3-point scale (grade 0 indicated a normal joint, grade 1 indicated mild to moderate degenerative change, and grade 2 indicated severe degenerative change). The value of findings on both routine radiographs and CT scans as predictors of the degree of symptomatic relief obtained from specific joint injections was determined. Arthrodesis was performed in nine patients on the basis of the results of anesthetic injections. RESULTS: The degree of pain relief experienced after intraarticular injection of anesthetic correlated with the severity of degenerative change as assessed by routine radiography in 15 of 32 joints and as assessed by CT in eight of 18 joints. In 14 of 32 joints assessed by routine radiography and in seven of 18 joints assessed by CT, the amount of pain relief achieved by anesthetic arthrography was less than that predicted by imaging evidence of degenerative disease. In five of 32 joints judged normal on plain film radiographs, significant pain relief was experienced following anesthetic injection, resulting in a change in the proposed surgical procedure. Long-term follow-up indicated satisfactory results in eight of the nine patients in whom arthrodesis was performed. CONCLUSION: Selective intraarticular anesthetic injections afford a direct method of confirming the site of hindfoot pain and may aid in surgical planning, because plain film radiography or CT may underestimate or poorly indicate the most symptomatic articulations.

Adult↗
PubMed1995

Synovial lesions of the hand and wrist.

Synovial tissue in the hand and wrist is frequently involved by inflammatory, degenerative, infectious, traumatic, metabolic, or neoplastic lesions. Although normal synovium is not shown on MR images, the morphology and signal characteristics of abnormal synovium is generally well demonstrated. Special MR techniques for accurate quantification of pannus are under investigation.

Adult↗