Radiolucencies are generally thought to be a manifestation of loosening. They are commonly seen under the tibial component of the Oxford Unicompartmental knee replacement. However, they are not associated with long term failure [ Eight medial Oxford Unicompartmental knee prostheses were examined post-operatively, at 12 months and at 24 months using Roentgen Stereophotogrammetric Analysis (RSA). The serial radiographs were calibrated and three dimensional CAD models were matched to the extracted component shapes. Implanted bone marker balls were then selected on all radiographs. The components were superimposed. Migration calculation was achieved by comparing relative positions of components to bone marker balls in the serial radiographs. Fluoroscopically screened X-rays were taken to determine whether there were any radiolu-cencies under the tibial component. By 12 months, the femoral component had migrated significantly anteriorly (0.35 mm) and proximally (0.61 mm). The tibial component had migrated significantly distally (0.42 mm) and anteriorly (0.47 mm). Although on average there appeared to be a small further migration between 12 and 24 months, this was not statistically significant in any direction. Six of the eight patients had radiolucencies at 24 months. None of the radiolucencies were was complete. The maximum radiolucency was 1 mm thick and the average was 0.57 mm. There was no correlation between radiolucency and migration. The proximal femoral migration and distal tibial migration can be explained by the load across the knee. We cannot yet explain the anterior tibial migration. Radiolucencies almost always occur and are not related to migration.This confirms they are not associated with loosening.
Two siblings with spondylothoracic dysostosis, and two siblings and three unrelated children with spondylocostal dysostosis are described. Both conditions are inherited and characterised by malformed thoracic and lumbar vertebrae. Spondylothoracic dysostosis produces "crab-like" deformities of the ribs, and is usually fatal during early infancy due to respiratory failure. Spondylocostal dysostosis causes short-trunked dwarfism but does not usually reduce life expectancy. These clinical features are distinct from congenital scoliosis, although all three conditions are associated with a particular group of malformations.
The clinical features of nine new patients with dysplasia epiphysialis hemimelica are reported, with a long-term follow-up on a further seven patients who were described in the earliest case reports of this disease. Each of these 16 patients had only one leg involved, but 12 had multiple epiphyses affected. The distal femur, distal tibia and talus were the commonest sites and most patients presented with painless swelling or deformity. Wasting of the muscles of the affected leg was a common finding, and was occasionally disproportionate to the degree of disuse. One patient had the unique combination of involvement of the lateral and medial halves of different epiphyses in the same limb and another had unusual metaphysial changes. Diagnosis was often delayed despite typical radiographic appearances. There was no evidence for a genetic component in the aetiology nor was any common environmental factor identified. Treatment by local excision was generally effective for lesions in the vicinity of the knee, but some patients with involvement of the talus required arthrodesis around the ankle. The long-term prognosis appears to be good and so far only two of these patients have developed premature osteoarthritis.
Thirty-four patients wtih fibrodysplasia (syn., myositis) ossificans progressiva are described. Marked delay in diagnosis was usual, but all had characteristic skeletal malformations and ectopic ossification. The clinical features included: four types of malformation of the big toe, reduction defects of all digits, deafness, baldness of the scalp, and mental retardation. Progression of disability was erratic in all, but severe restriction of movement of the shoulder and spine was usual by the age of 10 years; the hips were usually involved by the age of 20 years; and most patients were confined to a chair by the age of 30 years. Exacerbating factors included trauma to the muscles, biopsy of the lumps, operations to excise ectopic bone, intramuscular injections, careless venepuncture and dental therapy. Progression of disability did not appear to be influenced by any form of medical treatment and therefore management of the patients must concentrate on the avoidance of exacerbating factors.
