We performed a prospective study using MRI to evaluate early necrosis of the femoral head in 48 patients receiving high-dose corticosteroids for the treatment of various autoimmune-related disorders. The mean interval from the initiation of corticosteroid therapy to the first MRI examination was 2 months (0.5 to 6). MRI was repeated, and the mean period of follow-up was 31 months (24 to 69).

Abnormalities were found on MRI in 31 hips (32%). The initial changes showed well-demarcated, band-like zones which were seen at a mean of 3.6 months after initiation of treatment with steroids. In 14 of these hips (45%) there was a spontaneous reduction in the size of the lesions about one year after treatment had started, but there was no further change in size with a longer follow-up.

We reviewed 33 patients (35 hips) after open reduction of congenital dislocation of the hip using Ludloff’s medial approach. The mean age at the time of operation was 14 months (5 to 29) and at the time of final follow-up 20.1 years (15 to 24) giving a mean duration of follow-up of 19.4 years (14 to 23). We evaluated the radiological results by the Severin classification and the extent of avascular necrosis using the criteria of Kalamchi.

At the latest review 16 hips (45.7%) were in Severin groups I or II (acceptable results) and 19 (54.3%) in Severin groups III, IV or V (unacceptable results). There was evidence of avascular necrosis in 15 hips (42.9%). The radiological results began to become worse at about the age of ten years when type-II avascular changes presented.

We conclude that Ludloff’s medial approach for open reduction is unsatisfactory for the treatment of congenital dislocation since about half of our patients required additional operations.

The exact measurement of femoral head cover is essential for an assessment of reduction of congenital dislocation of the hip. We have compared standard anteroposterior radiographs with computerised tomograms and thereby classified the shape of the acetabular roof into four types. We found that the CE angle of Wiberg is a more reliable measure of head cover when the lateral point of bony condensation of the roof is chosen as the reference point rather than the edge of the bone, where these two points do not overlap. We conclude that head cover can be more accurately determined in younger children with dysplastic hips by our 'refined' CE angle, than by the original method of Wiberg.

Hip arthrography was performed in 19 patients in the initial stage of Perthes' disease. Sphericity and subluxation were measured and it was found that subluxation was independent of the femoral head deformity. We therefore tried to identify the cause of early subluxation: in seven patients a swollen ligamentum teres was thought to be responsible, and was associated with medial pooling of the contrast medium. A swollen ligamentum teres was seen in another seven cases; the other five arthrograms were normal. These findings were further clarified by enhanced CT scans, which confirmed that ligament swelling may be an important cause of early subluxation.