Lateral ulnar collateral ligament of the elbow: optimization of evaluation with two-dimensional MR imaging.

PURPOSE: To compare, in a cadaveric model, magnetic resonance (MR) imaging techniques with differing contrast and spatial resolution properties in the evaluation of disruption of the lateral ulnar collateral ligament (LUCL) at the elbow. MATERIALS AND METHODS: LUCL tears were surgically created in eight of 28 cadaveric elbow specimens. All specimens underwent 1.5-T MR imaging with the following pulse sequences: T1-weighted spin echo (SE), intermediate-weighted fast SE, fat-suppressed T2-weighted fast SE, gradient-recalled echo (GRE) with high spatial resolution, intermediate-weighted fast SE with high spatial resolution, and fat-suppressed T1-weighted SE with intraarticular administration of gadopentetate dimeglumine (MR arthrography). All images were obtained in the oblique coronal plane. Two radiologists independently graded the LUCL with separate and side-by-side assessment. RESULTS: Areas under the receiver operating characteristic curve were as follows for readers A and B, respectively: T1-weighted SE imaging, 0.64 and 0.62; intermediate-weighted fast SE imaging, 0.87 and 0.67; T2-weighted fast SE imaging, 0.68 and 0.69; GRE imaging, 0.56 and 0.68; MR arthrography, 0.84 and 0.85; and intermediate-weighted imaging with high spatial resolution, 0.92 and 0.88. Interobserver reliability was poor with T1-weighted SE imaging (kappa = 0.13) and GRE imaging (kappa = 0.18), fair with T2-weighted fast SE imaging (kappa = 0.36), and moderate with MR arthrography (kappa = 0.46), intermediate-weighted fast SE imaging (kappa = 0.55), and intermediate-weighted imaging with high spatial resolution (kappa = 0.59). CONCLUSION: Intermediate-weighted imaging with high spatial resolution and MR arthrography showed the greatest overall ability to enable the diagnosis of LUCL tears.

Noncontrast MR imaging and MR arthrography of the ulnar collateral ligament of the elbow: prospective evaluation of two-dimensional pulse sequences for detection of complete tears.

OBJECTIVE: To compare MR imaging techniques with differing contrast and spatial resolution for evaluation of complete disruption of the ulnar collateral ligament (UCL) anterior bundle in a cadaveric elbow model. DESIGN: Complete UCL tears were surgically created at the typical location for clinical tears in eight of 28 fresh frozen cadaveric elbow specimens. All specimens underwent 1.5 T MR imaging in the oblique coronal plane, using an extremity coil. The sequences employed were: T1-weighted spin echo (T1 SE), proton density-weighted (PD) fast spin echo (FSE), fat-suppressed T2-weighted FSE (T2 FSE), gradient recalled echo (GRE) with a high matrix, PD FSE with a high matrix (HRPD), and fat suppressed T1-weighted SE with intra-articular gadolinium (MRAr). Two radiologists independently graded the UCL with separate and side-by-side assessments. RESULTS: Sensitivity/specificity pairs were as follows for reader A and reader B, respectively: T1 SE: 0.25/0.95, 0.50/0.95; PD FSE: 0.38/1.00, 0.25/1.00; T2 FSE: 0.50/0.95, 0.63/0.95; GRE: 0.63/0.85, 0.63/0.60; MRAr: 0.88/1.00, 1.00/0.80; HRPD: 0.50/1.00, 0.88/0.80. Kappa statistics for measuring interobserver reliability for each sequence were poor under T1 SE (-0.13) and GRE (0.19), moderate under HRPD (0.41) and T2 FSE (0.44) and good under MRAr (0.62) and PD FSE (0.78). For both readers, the rating for overall image quality was highest for HRPD, and the rating for UCL lesion conspicuity was the highest for MRAr. CONCLUSIONS: Of the MR imaging pulse sequences tested, MRAr showed the greatest ability to identify complete ligamentous injuries with good agreement between readers and had the highest subjective preference for lesion conspicuity. However, HRPD had the least interobserver variability and the highest subjective preference for overall image quality.

Muscle infarction in patients with diabetes mellitus: MR imaging findings.

PURPOSE: To describe the magnetic resonance (MR) imaging findings in diabetic patients with muscle infarction and to describe commonly associated clinical features. MATERIALS AND METHODS: The MR imaging studies of 21 patients with diabetic muscle infarction were reviewed retrospectively. Of the 21 patients, 12 were women, and nine were men; the mean age was 48 years (range, 30-77 years). RESULTS: Eight patients had bilateral lower-extremity involvement; six had involvement confined to the right lower extremity and seven to the left. The thigh was involved in 17 patients (81%). One or more of the musculi vastus, the most frequently affected muscle group, were affected in 16 patients (76%). Four patients (19%) had isolated calf involvement. MR imaging studies showed diffuse enlargement of involved muscle groups and partial loss of normal fatty intermuscular septa. MR imaging also allowed identification of areas of subfascial fluid in 16 patients (76%) and subcutaneous edema in 19 patients (90%). MR imaging showed involved muscle groups best with T2-weighted, inversion-recovery, and gadolinium-enhanced sequences, where the infarcted muscles appeared diffusely hyperintense compared with adjacent muscles. Comparison of T2-weighted and gadolinium-enhanced MR images of nine patients showed enlarged, enhancing muscles in all patients and small, focal, rim-enhancing fluid collections in six of nine patients (66%). CONCLUSION: Diabetic muscle infarction is suggested in diabetic patients with sudden onset of severe pain in the thigh or calf muscles who have MR imaging findings of diffuse edema and swelling of multiple thigh and calf muscles (often in more than one compartment).

MR imaging findings in anterior cruciate ligament reconstruction: evaluation of notchplasty.

OBJECTIVE: Notchplasty, resection of bone from the roof and lateral side of the inter-condylar notch, is frequently performed during anterior cruciate ligament (ACL) reconstruction to avoid abrasion or deflection of the ACL graft by the femur (graft impingement). Graft impingement can develop months after the initial reconstruction despite adequate notchplasty. Such impingement has recently been attributed to fibrocartilage overgrowth of the notchplasty site. The objectives of this study were to evaluate the MR appearance of the notchplasty site immediately after surgery and 6 months later and to investigate whether cartilage overgrowth of the notchplasty site can be detected with MR imaging. SUBJECTS AND METHODS: Thirty-three patients who underwent bone-tendon-bone autograft ACL reconstruction had MR scans of the intercondylar notch 6 months after surgery. Twenty-five of these patients also had MR scans in the immediate postoperative period. The appearance of the notchplasty site and evidence for cartilage overgrowth of the notchplasty site were evaluated. Arthroscopic correlation was available for six patients. RESULTS: On MR images, the margins of the notchplasty site were identified in all patients. Contour of the notchplasty site along the lateral notch wall was frequently concave toward the notch, a finding not commonly seen in an unoperated notch. Six months later, the shape of the notchplasty site had not changed, but evidence for recortication of the notchplasty site (seen as a layer of signal void 0.5-1.5 mm in thickness over the previously exposed cancellous bone) was seen in 94% of the patients. Additionally, a second layer of signal void, 1-5 mm in thickness with signal intensity identical to that of hyaline cartilage, was seen overlying the notchplasty site in 64% of patients. Arthroscopic correlation available in six patients suggested that this second layer represented fibrocartilage overgrowth of the notchplasty site. CONCLUSION: Characteristic changes of the intercondylar notch after notchplasty can be seen on MR images. This preliminary study also suggests that a thin layer of cortical bone forms over the notchplasty site in most patients within 6 months of surgery. Perhaps more significantly, overgrowth of the notchplasty site by fibrocartilage may also be detected in some patients. Further experience is needed to determine whether MR imaging is a useful method for identifying cartilage overgrowth after notchplasty.

Lateral-compartment bone contusions in adolescents with intact anterior cruciate ligaments.

PURPOSE: To determine how often lateral-compartment bone contusions are seen on magnetic resonance (MR) images of knees in adolescents with intact anterior cruciate ligaments (ACLs). MATERIALS AND METHODS: MR images obtained in 53 adolescent patients (30 male, 23 female; aged 10-20 years) were reviewed to detect bone contusions in the posterolateral tibial plateau or the lateral femoral condyle. ACLs were also evaluated with accepted criteria for the diagnosis of ligamental disruption. Only patients referred for evaluation of a knee injury or mechanical symptoms were included. RESULTS: Five patients with bone contusions had an intact ACL at MR imaging. One of the five had arthroscopic confirmation. Fifteen other patients had complete ACL disruptions: 13 of these patients had typical bone contusions; the other two had no bone abnormalities but had chronic ACL tears. Thus, 28% of the 18 patients with typical bone contusions had intact ACLs. CONCLUSION: Adolescents may have the same pattern of contusions as adults but may maintain an intact ACL owing to increased ligamentous laxity.

Lunotriquetral interosseous ligament of the wrist: MR appearances in asymptomatic volunteers and arthrographically normal wrists.

PURPOSE: To determine whether the carpal lunotriquetral ligament (LTL) can be consistently seen and to establish the normal range of LTL appearances at magnetic resonance (MR) imaging as a basis for comparison with LTL tears. MATERIALS AND METHODS: MR imaging was used to identify and characterize the LTL in 75 wrists with normal LTLs (54 in 27 asymptomatic volunteers, 21 in patients with normal arthrograms). RESULTS: The LTL was identified in all wrists and was linear in 63% and delta-shaped in 35%. The LTL had homogeneous low signal intensity in 73% and linear intermediate signal intensity traversing all or part of the LTL in 25%. Fluid signal intensity traversed the LTL in only one wrist. MR appearance of the osseous insertion sites varied. Distribution of hyaline cartilage signal was related to location within the LTL. CONCLUSION: The LTL can be consistently identified at MR imaging, but its appearance varies, which must be appreciated when evaluating wrists with suspected LTL tears.

Management of ankle deformities in multiple hereditary osteochondromata.

Nine patients with multiple hereditary osteochondromata underwent ankle surgery for valgus deformity. The indications for operation included pain from trauma of the prominent masses, pain in the ankle joint associated with the deformity, limited ankle motion, and undesirable cosmesis. The procedures included excision of osteochondromata, fibular lengthening, and medial tibial hemiepiphyseal retardation by inserting staples. Excision of osteochondromata as an isolated procedure relieved pain and improved cosmesis but did not alter the tibiofibular length discrepancy or the ankle valgus. Lengthening of the fibula and medial tibial hemiepiphyseal stapling, alone or in combination, corrected the valgus deformity of the ankle. At final follow-up (mean 43 months), no patient had pain or functional impairment.