Mark S. Collins

Secondary chondrosarcoma in osteochondroma: report of 107 patients.

Secondary chondrosarcomas are rare; recognition and diagnosis are difficult. Slow growth and late recurrence require long-term followup to understand the clinical course. In the current study, 107 patients had secondary chondrosarcoma arising in a solitary osteochondroma (61 patients) or multiple exostoses (46 patients). All histologic slides were reviewed without knowledge of the outcome, and radiologic studies were available for review in 71 cases. Patients with secondary chondrosarcoma were one to two decades younger than those with primary chondrosarcoma. Male preponderance and a predilection for flat bones were observed. The radiologic signs of sarcomatous degeneration included irregularity of the margin, inhomogeneous mineralization, and an associated soft tissue mass. The tumors generally were well-differentiated. Only 10 tumors were classified as Grade 2. Five-year and 10-year local recurrence rates were 15.9% and 17.5%, respectively, and 5- and 10-year mortality rates were 1.6% and 4.8% for patients having initial treatment at the authors’ institution. Metastasis developed in five patients: in the lung in four patients and in the groin region in one patient. Most patients who died of tumor died of local recurrence. Wide excision had the lowest local recurrence rate. With successful surgical treatment, patients may have long-term disease-free survival.

CT and MRI Measurements of Tibial Tubercle–Trochlear Groove Distances Are Not Equivalent in Patients With Patellar Instability

Background: Tibial tubercle–trochlear groove distance (TT-TG) is a commonly used measurement for surgical decision making in patients with patellofemoral malalignment and instability. This measurement has historically been performed utilizing axial computed tomography (CT). More recently, magnetic resonance imaging (MRI) has been proposed as an equivalent method, but this has not yet been fully validated. Purpose: To determine the reliability of TT-TG distance measurements on both MRI and CT and to determine whether the measurements are interchangeable with one another. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: All patients with patellar instability who underwent both CT and MRI of the knee from 2003 to 2011 were included (n = 59 knees in 54 patients). Two fellowship-trained musculoskeletal radiologists measured the TT-TG distances for each patient by CT and MRI in a randomized, blinded fashion. Interobserver reliability was calculated between radiologists for both imaging modalities, and intermethod reliability was calculated between the 2 imaging modalities. The results are reported using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Results: The 59 knees had a mean TT-TG distance of 16.9 mm (range, 8.3-25.8 mm) by CT and 14.7 mm (range, 1.5-25.1 mm) by MRI. Interobserver reliability between the radiologists was considered excellent for both CT and MRI (ICC = 0.777 and 0.843, respectively). When comparing CT to MRI, the ICC was considered only fair for each of the raters (0.532 and 0.539). Eleven patients (19%) had a TT-TG distance of ≥20 mm on CT preoperatively and underwent distal realignment by tibial tubercle osteotomy. In this surgical subgroup, the mean TT-TG distance was 22.5 mm (range, 19.8-25.8 mm) by CT and only 18.7 mm (range, 14.4-22.8 mm) by MRI for a mean difference of 3.80 mm (P < .001). Conclusion: The TT-TG distance can be measured with excellent interrater reliability on both MRI and CT; however, the values derived from these 2 tests may not be interchangeable. This observation should be taken into consideration when MRI is used for surgical planning because MRI may underestimate the TT-TG distance when compared with CT.

Lateral Tibial Posterior Slope Is Increased in Patients With Early Graft Failure After Anterior Cruciate Ligament Reconstruction

Background: The lateral tibial posterior slope (LTPS) has been reported in multiple studies to correlate with an increased risk for native anterior cruciate ligament (ACL) tearing. To date, no study has examined the effect of an increased LTPS as measured on magnetic resonance imaging (MRI) on the likelihood of ACL graft failure. Hypothesis: An increased LTPS as measured on MRI would correlate with an increased risk for ACL graft failure. Study Design: Case-control study; Level of evidence, 3. Methods: Fifty-eight patients were initially identified who experienced graft failure after primary ACL reconstruction and underwent revision between 1998 and 2009. Exclusion criteria were clinical follow-up of less than 4 years, graft failure occurring greater than 2 years after primary surgery, skeletal immaturity, deep infection, lack of available preoperative MRI, and history of trauma to the proximal tibia. This left 35 patients with early (within 2 years) failure of primary ACL reconstruction. These patients were matched to 35 control participants who had undergone ACL reconstruction with a minimum of 4 years of clinical follow-up and no evidence of graft failure. Patients were matched by age, sex, date of primary surgery, and graft type. The LTPS was then determined on MRI in a blinded fashion. Results: The mean time to failure in patients in the study group was 1 year (range, 0.6-1.4 years). The mean follow-up of those in the matched control group was 6.9 years (range, 4.0-13.9 years). The mean LTPS in the early ACL failure group was found to be 8.4°, which was significantly larger than that in the control group at 6.5° (P = .012). The odds ratio for graft failure considering a 2° increase in the LTPS was 1.6 (95% CI, 1.1-2.2) and continued to increase to 2.4 (95% CI, 1.2-5.0) and 3.8 (95% CI, 1.3-11.3) with 4° and 6° increases in the LTPS, respectively. No significant association was identified between graft type and graft failure. Conclusion: An increased LTPS is associated with an increased risk for early ACL graft failure, regardless of graft type. Orthopaedic surgeons should consider measuring the LTPS as part of the preoperative assessment of ACL-injured patients.

Diagnostic Utility of T1-Weighted MRI Characteristics in Evaluation of Osteomyelitis of the Foot

OBJECTIVE The purpose of this study was to evaluate the diagnostic utility of specific characteristics on T1-weighted MR images in the diagnosis of pedal osteomyelitis. MATERIALS AND METHODS The study included all adult patients who underwent MRI of the foot for evaluation of suspected osteomyelitis over an 11-month period. Images were retrospectively reviewed for specific criteria on T1-weighted images, including signal intensity of affected bone marrow (normal or decreased), distribution of abnormal signal intensity (subcortical or medullary), and pattern of involvement (hazy reticulated or confluent). The presence of osteomyelitis was presumed if the surgical pathologic result was positive or if there was lack of clinical improvement despite conservative management. Rapid clinical improvement with conservative management was considered an indication that osteomyelitis was not present. RESULTS Images from 74 examinations were evaluated. In 20 cases, osteomyelitis was considered present, and in 54 it was presumed absent. In 19 of the 20 cases (95%) in which osteomyelitis was considered present, marrow T1 signal intensity was decreased, in a medullary distribution, and in a confluent pattern in all cases. In 30 of the 54 cases (56%) in which osteomyelitis was presumed absent, T1 signal intensity was decreased, but only five cases (9%) had a medullary distribution and confluent pattern. Twenty-three cases (43%) had a hazy reticulated pattern, and two cases (4%) had only subcortical distribution. None of the cases with a subcortical distribution or hazy reticulated pattern of abnormal signal intensity had positive results for osteomyelitis. Confluent decreased T1 marrow signal intensity in a medullary distribution was 95% sensitive in the prediction of osteomyelitis with a specificity of 91%, negative predictive value of 98%, and positive predictive value of 79%. CONCLUSION Findings on T1-weighted MR images, specifically a confluent pattern of decreased T1 marrow signal intensity in a medullary distribution, correlate highly with the presence of pedal osteomyelitis.

Magnetic resonance imaging of acute "wiiitis" of the upper extremity.

We present the first reported case of acute “wiiitis”, documented clinically and by imaging, of the upper extremity, caused by prolonged participation in a physically interactive virtual video-game. Unenhanced magnetic resonance imaging (MRI) demonstrated marked T2-weighted signal abnormality within several muscles of the shoulder and upper arm, without evidence of macroscopic partial- or full-thickness tearing of the muscle or of intramuscular hematoma.

An institutional review of clear cell chondrosarcoma.

Clear cell chondrosarcoma is a rare bone neoplasm with a slow progressive clinical course and infrequent metastasis, but with a high local recurrence rate. We sought to ascertain the long-term outcome of patients with this neoplasm and to identify possible factors predicting survival. Sixteen patients with clear cell chondrosarcomas treated at one institution and who had long-term clinical followup were identified. All patients were treated by surgical resection of the tumor, which was classified as clear (> 2 mm) in 10 patients and marginal or intralesional in six patients. Three patients had local recurrence after a median of 1.7 years. Metastatic disease developed in four patients with a median time to diagnosis of 8.1 years. Ten-year overall survival of patients with clear cell chondrosarcomas was 89%, and disease-free survival was 68%. Patients with surgical resections comprising clear margins had longer disease-free survival compared with patients with marginal and intralesional tumors. Inadequate surgical resection of clear cell chondrosarcoma leads to risk of local recurrence and metastatic disease. The malignancy has a tendency to metastasize relatively late, therefore, followup of patients is necessary after the generally accepted 5-year period. Level of Evidence: Prognostic study, Level III (case control study). See the Guidelines for Authors for a complete description of levels of evidence.

Variability of the Ischiofemoral Space Relative to Femur Position: An Ultrasound Study

Ischiofemoral impingement is caused by compression of the quadratus femoris muscle between the ischial tuberosity and lesser trochanter. The evaluation of ischiofemoral impingement includes radiologic studies to evaluate the ischiofemoral space dimensions. No prior study has evaluated the effect of femoral position on ischiofemoral space dimensions.

Imaging Evaluation of Chronic Ankle and Hindfoot Pain in Athletes

Acute ankle and hindfoot injuries are common in athletes and typically are treated conservatively. Persistent pain that has not responded to appropriate conservative treatment and prevents the patient from returning to play is more problematic for the athlete and the treating sports clinician. Making a specific clinical and imaging diagnosis in these patients can be quite challenging. This article discusses the imaging evaluation of chronic ankle and hindfoot pain related to osseous and soft-tissue injuries in athletes. MR imaging is the preferred imaging modality in most of the presented cases.

Use of IV epinephrine for treatment of patients with contrast reactions: lessons learned from a 5-year experience.

OBJECTIVE The purpose of this study was to review the use of epinephrine in the management of contrast reactions and to evaluate the appropriateness of the clinical indication, side effects and complications, and outcome. CONCLUSION Severe contrast reactions necessitating treatment with epinephrine are rare. The most common clinical indication is laryngeal edema. Cardiovascular side effects of epinephrine occur, but most are self-limited.

The “sliver sign”: a specific radiographic sign of acute lateral patellar dislocation

ObjectiveThe objective of this work is to assess the prevalence of the sliver sign, defined as an intraarticular linear or curvilinear ossific density, in association with knee effusion in patients with acute knee trauma, as a predictor of recent lateral patellar dislocation (LPD).Materials and methodsA retrospective radiology database search for the term ‘patellar dislocation’ on MRI knee exams performed at our institution over a 7-year period identified 216 studies. Of these, 142 exams met true positive gold standard diagnostic criteria for LPD. Imaging findings of both the retrospectively identified radiographs and subsequent MRI were recorded. Accuracy of radiographic interpretation was also analyzed.ResultsAfter review by an experienced musculoskeletal radiologist, 27 patients (19%) with LPD had knee radiographs demonstrating intraarticular osseous fragments. The majority of these patients had fragments (22/27, 81%) that were linear or curvilinear in configuration. A smaller subset of patients had fragments (5/27, 19%) that were rounded or oblong, felt to most likely represent sequelae of chronic dislocation. The fragments were identified on the patellar view only in eight of 27 patients (30%). These fragments were often initially misinterpreted, with the diagnosis explicitly stated in the report in 2/27 cases (7%). More often, the fractures were described vaguely (13/27, 48%), interpreted incorrectly (6/27, 22%), or missed (6/27, 22%). All 27 patients had moderate or large knee joint effusions.ConclusionsIn the setting of acute knee trauma, knee radiographs demonstrating a joint effusion and an intraarticular sliver-like osseous fragment correlate with recent lateral patellar dislocation. The routine trauma knee radiographic series does not include a patellar view but probably should, especially in young patients.