PURPOSE

Osteochondral talar defects (OCDs) are sometimes located so far posteriorly that they may not be accessible by anterior arthroscopy, even with the ankle joint in full plantar flexion, because the talar dome is covered by the tibial plafond. It was hypothesized that computed tomography (CT) of the ankle in full plantar flexion could be useful for preoperative planning. The dual purpose of this study was, firstly, to test whether CT of the ankle joint in full plantar flexion is a reliable tool for the preoperative planning of anterior ankle arthroscopy for OCDs, and, secondly, to determine the area of the talar dome that can be reached by anterior ankle arthroscopy.

Peri-articular soft-tissue masses or ‘pseudotumours’ can occur after large-diameter metal-on-metal (MoM) resurfacing of the hip and conventional total hip replacement (THR). Our aim was to assess the incidence of pseudotumour formation and to identify risk factors for their formation in a prospective cohort study.

A total of 119 patients who underwent 120 MoM THRs with large-diameter femoral heads between January 2005 and November 2007 were included in the study. Outcome scores, serum metal ion levels, radiographs and CT scans were obtained. Patients with symptoms or an identified pseudotumour were offered MRI and an ultrasound-guided biopsy.

There were 108 patients (109 hips) eligible for evaluation by CT scan at a mean follow-up of 3.6 years (2.5 to 4.5); 42 patients (39%) were diagnosed with a pseudotumour. The hips of 13 patients (12%) were revised to a polyethylene acetabular component with small-diameter metal head. Patients with elevated serum metal ion levels had a four times increased risk of developing a pseudotumour.

This study shows a substantially higher incidence of pseudotumour formation and subsequent revisions in patients with MoM THRs than previously reported. Because most revision cases were identified only after an intensive screening protocol, we recommend close monitoring of patients with MoM THR.

Background: This study tested the null hypothesis that computed tomography (CT) and magnetic resonance imaging (MRI) have the same diagnostic performance characteristics for triage of suspected scaphoid fractures.

Methods: Thirty-four consecutive patients with a suspected scaphoid fracture (post-injury tenderness of the scaphoid and normal radiographs) underwent CT and MRI within ten days after trauma. CT-reconstructions were made in planes defined by the long axis of the scaphoid. The reference standard for a true fracture of the scaphoid was 6-week follow-up radiographs in four views, based on current literature. A panel including surgeons and radiologists came to a consensus diagnosis for each type of imaging considered in a randomized and blinded fashion, independent of the other types of imaging. We calculated sensitivity, specificity and accuracy as well as positive (PPV) and negative predictive values (NPV) for both imaging modalities.

Results: According to the reference standard there were six true fractures of the scaphoid (prevalence 18%). CT diagnosed fracture of the scaphoid in five patients (15%), with one false positive, two false negative and four true positive results. MRI diagnosed a fracture in seven patients (21%), with three false positive, two false negative and four true positive results. Sensitivity, specificity and accuracy for CT were 67%, 96% and 91%; and for MRI 67%, 89% and 85% respectively. According to the McNemar test for paired binary data for each imaging modality these differences were not significant. The positive predictive values using Bayes’ formula were 76% for CT and 54% for MRI. Negative predictive values were 94% for CT and 93% for MRI.

Conclusions: CT and MRI had comparable diagnostic characteristics. Both were subject to both false positive and false negative interpretations. They were better to rule out a fracture than to rule one in. The best reference standard for a true fracture is debatable

Our aim in this prospective study was to determine the best diagnostic method for discriminating between patients with and without osteochondral lesions of the talus, with special relevance to the value of MRI compared with the new technique of multidetector helical CT. We compared the diagnostic value of history, physical examination and standard radiography, a 4 cm heel-rise view, helical CT, MRI, and diagnostic arthroscopy for simultaneous detection or exclusion of osteochondral lesions of the talus. A consecutive series of 103 patients (104 ankles) with chronic ankle pain was included in this study. Of these, 29 with 35 osteochondral lesions were identified. Twenty-seven lesions were located in the talus.

Our findings showed that helical CT, MRI and diagnostic arthroscopy were significantly better than history, physical examination and standard radiography for detecting or excluding an osteochondral lesion. Also, MRI and diagnostic arthroscopy performed better than a mortise view with a 4 cm heel-rise. We did not find a statistically significant difference between helical CT and MRI. Diagnostic arthroscopy did not perform better than helical CT and MRI for detecting or excluding an osteochondral lesion.

Vascular malformations are rare congenital lesions which often have associated skeletal changes. Over a period of ten years, 90 patients at our clinic had a vascular anomaly of the lower limb, examined by either CT or MRI. Of these, 18 (20%) had bony involvement. A questionnaire was sent to these patients (8 men, 10 women) to evaluate their age of presentation, initial symptoms and current complaints. Radiological imaging revealed 15 low- and three high-flow lesions. The mean age at presentation to a physician was six years of age. Pain was the most common complaint. Disparity in leg length of 2 cm or more was observed in ten patients. Of the 16 patients with muscle infiltration, 13 had four or more muscles involved. Treatment by resection alone would require radical surgery.