Anatomic variations in the first extensor compartment of the wrist: accuracy of US.

PURPOSE: To evaluate the accuracy of ultrasonography (US) in determining the anatomic variations in the first extensor compartment of the wrist. MATERIALS AND METHODS: Approval from the anatomic donations department was obtained. The first extensor compartment of the wrist of 40 nonembalmed cadaveric forearms (15 male and 25 female; age range at death, 65-100 years) were assessed at US by two observers for the presence or absence of a vertical septum, the presence or absence of an osseous ridge with a double groove in the bony floor, and whether there were single or multiple slips of the abductor pollicis longus and the extensor pollicis brevis tendons. These findings were also evaluated at dissection. RESULTS: The accuracies of US in depicting a septum and an osseous ridge with a double groove were respectively 95% (95% confidence interval [CI]: 83%, 99%) and 100% (95% CI: 91%, 100%). At dissection, a septum was invariably associated with the presence of an osseous ridge. The accuracies of US in depicting multiple tendon slips of the abductor pollicis longus and the extensor pollicis brevis were respectively 80% (95% CI: 64%, 91%) and 97% (95% CI: 86%, 100%). CONCLUSION: US was highly accurate in depicting anatomic variations in the first extensor compartment. US detection of an osseous ridge was an indirect sign of the presence of a septum dividing the first extensor compartment into two subcompartments.

SAPHO syndrome: MR appearance of vertebral involvement.

PURPOSE: To retrospectively evaluate the magnetic resonance (MR) imaging findings of vertebral involvement in patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. MATERIALS AND METHODS: Ethics committee approval and informed patient consent were not required for this retrospective study. MR images obtained in 12 patients (seven female, five male; mean age, 42 years; range, 16-65 years) with SAPHO syndrome involving the spine were reviewed. One vertebral lesion separated by one or more normal vertebrae was analyzed as a distinct lesion. For each lesion, the number of associated vertebrae with abnormal signal intensity (SI) (ie, single vertebra, two adjacent vertebrae, or more than two adjacent vertebrae) was noted. The following MR imaging findings were evaluated: cortical bone erosion, abnormal vertebral body SI compared with normal vertebral body SI, increased anteroposterior diameter of the vertebral body, soft-tissue involvement, vertebral body height loss of more than 30%, and abnormal SI of the adjacent intervertebral disk compared with the SI of the other disks. RESULTS: Of 24 vertebral lesions found, 17 involved a single vertebra, four involved two adjacent vertebrae, and three involved three or four adjacent vertebrae. Vertebral corner cortical erosion was present in all lesions, and 23 (96%) lesions had anterior vertebral corner involvement. The erosion was confined to a vertebral corner in five (21%) lesions and included the adjacent endplate and/or the anterior cortex of the vertebral body in the remaining 19 (79%) lesions. In four (17%) lesions, involvement of two adjacent vertebral corners on either side of an intervertebral disk mimicked to some extent early disk space infection. An adjacent disk space was narrowed in six (25%) lesions and exhibited abnormal SI in two (8%). Prevertebral tissue thickening was observed in eight (33%) lesions. CONCLUSION: Erosion of a vertebral body corner is consistently seen on MR images of SAPHO vertebral lesions and may support the diagnosis of SAPHO syndrome in the appropriate clinical context.