We reviewed 12 patients six years after they had undergone total hip replacement with a cementless prosthesis, the Ribbed Hip System (Waldemar Link GmbH & Co, Hamburg, Germany). Aseptic loosening of one or both components had necessitated revision surgery in seven patients, in five within two years of operation. In view of our experience we question the wisdom of allowing the uncontrolled use of new prosthesis without postoperative surveillance.

Dual-energy X-ray absorptiometry (DEXA) is increasingly used to measure changes in bone mineral density (BMD) around femoral prostheses after total hip arthroplasty. We have studied the factors which affect the accuracy of these measurements. The coefficient of variation was < 2% using a hydroxyapatite phantom, 2.7% in an anthropomorphic phantom specimen, and < 1% in repeated measurements on implanted cadaver femora. The precision did not vary with different implant materials or designs. In patients we found a mean precision error of 2.7% to 3.4%. The most significant factor affecting reproducibility was rotation of the femur. We conclude that DEXA is a precise method of measurement for small changes in BMD around femoral implants, but that correct and careful positioning of patients is essential to obtain reliable results.

The prevalence of HIV infection in East Africa has increased rapidly in recent years. We made a prospective study of the incidence of HIV-seropositivity in patients undergoing orthopaedic procedures in a large district hospital in Bulawayo, Zimbabwe. One of our aims was to determine whether a clinically-based screening programme, derived from the Centre for Disease Control classification of HIV infection, could identify high-risk individuals before surgery. During a 3-month period, 76 patients were tested, and 12 were HIV-positive (16%). Only two of these patients (17%) had clinical features associated with HIV infection; ten (83%) were entirely asymptomatic. Our results indicate that preoperative clinical screening is unlikely to be successful in identifying seropositive patients before routine surgery.

We studied the pedigrees of 17 index patients with osteosarcoma, recording malignant disease and cause of death for first- and second-degree relatives. There were seven cancers and five cancer deaths per 2151.5 person-years in first-degree relatives of osteosarcoma patients under the age of 50 years, a significantly greater incidence than in an age- and sex-matched population group (p < 0.001). This excess of malignancy was largely due to two families which fulfilled the criteria for the Li-Fraumeni cancer family syndrome. Both of these families were shown to have the genetic alterations in the p53 gene which have been implicated in this syndrome. Our study suggests that orthopaedic surgeons seeing new cases of osteosarcoma should arrange screening for familial malignancy.

The nerve roots of the cauda equina may be visualised by contrast-enhanced CT scans and by surface-coil MRI. We have identified the pattern of anatomy from L2-L3 to L5-S1 in 10 human cadaver specimens and correlated this with anatomical dissections. Individual roots are slightly more distinct on contrast-enhanced CT than on surface-coil MRI. There is a crescentic oblique pattern of nerve roots at the lower lumbar levels which is still apparent in the more crowded proximal sections. In all cases, the axial images correlated precisely with the dissections. Current imaging modalities can help the clinical understanding and management of abnormalities in this region of the spine.

Prompt surgical decompression is the only means of preventing the late sequelae of ischaemic contracture in post-traumatic compartment syndromes. However, controversy exists regarding the length of dermotomy required for adequate decompression in the lower extremity. This study investigated the skin envelope as a potential contributing factor. Wide fascial releases were performed through limited 8 cm incisions in eight cases of post-traumatic lower extremity compartment syndrome. In nine of 29 compartments the pressure remained greater than 30 mmHg. Lengthening the skin incisions to an average of 16 cm decreased intracompartmental pressures significantly. This study documents the skin envelope as a contributing factor in acute compartment syndromes of the leg. The use of generous skin incisions is supported and the need for intra-operative compartment pressure measurements in the treatment of this condition is emphasised.

Hip rotation in extension and flexion was studied in 23 patients with idiopathic intoeing gait. In extension all the hips had markedly increased medial rotation and limited lateral rotation, fulfilling the criteria of excessive femoral anteversion. In flexion, however, rotation varied widely; in one group of patients medial rotation remained greater than lateral, but in the second group lateral rotation was equal to or greater than medial. CT scans showed that the hips in the first group were significantly more anteverted than those in the second. Clearly measurement of hip rotation in extension alone does not provide a dependable indication of femoral anteversion in children with intoeing gait; rotation in flexion also needs to be measured.

In controlled clinical studies of adult diabetics a 42% incidence of signs of Dupuytren's disease was found. The incidence was highest in the older patients with a longer history of diabetes, but was not related to the severity of the diabetes. The features of Dupuytren's disease in the diabetics has a distinctive pattern, being more severe in men than women and, compared with controls, having a radial shift towards the middle finger. The disease was mild and of benign prognosis, rarely needing operation. In a further study, 13% of patients with Dupuytren's disease were found to have a raised blood glucose level. The question is posed as to whether the biochemical disturbance causes the Dupuytren's disease or whether the pattern of inheritance predisposes to both Dupuytren's disease and diabetes.

Scoliosis Clinic and the Department of Human Genetics, Hadassah University Hospital, Jerusalem Scoliosis appeared in fifteen members of a family in three generations. The eight members examined showed an idiopathic type of scoliosis. Father-to-son transmission occurred more than once. Although at first appearance transmission of the scoliosis is as an autosomal dominant trait, the concept of polygenic inheritance, as has been shown in previous population studies, could also explain the inheritance in this family

1. Four cases of abnormal arrangement of the lower lumbar and sacral nerves within the spinal canal are reported.

2. In all four cases the presentation was like that associated with acute lumbar disc protrusion, though in only two cases was a protrusion found at operation.

3. The significance of the findings is discussed and the findings are compared with those in the eighteen other recorded cases.

1. Epidural abscess should be suspected in patients with lumbar and sciatic pain who have a history of staphylococcal skin infections or of diabetes.

2. The diagnosis of epidural abscess should be considered before that of herniation of a disc if the patient presents an otherwise unexplained pyrexia. The absence of radiographic changes is no bar to this diagnosis.

3. The hazards of lumbar puncture in cases of epidural abscess are obvious.

4. Early diagnosis and operation are essential to control the infective lesion and to ensure recovery of the neural lesion.

Twenty-one post-irradiation fractures of the femoral neck are reported in seventeen patients who had been treated by radiotherapy for carcinoma of the uterus.

The clinical and radiological appearances are described and the diagnosis, prognosis and treatment of this type of fracture are discussed.

Histological material has been studied in three cases.

It is concluded:

1. That there is a characteristic clinical picture in which premonitory pain is of paramount significance.

2. That when the diagnosis is considered, the likelihood of irradiation damage should take precedence over the remote possibility of metastatic invasion.

3. That the disability varies, but in general the prognosis is favourable.

4. That there is no specific line of treatment applicable to these fractures.

5. That avascularity is not the underlying cause of this lesion.

1. In patients who develop de Quervain's disease variations from the standard pattern of tendons at the wrist are the rule rather than the exception.

2. Conservative treatment is of no value.

3. Adequate exposure, allowing full recognition of all anatomical structures in the region, is advisable, but branches of the radial nerve must be treated with respect.

4. The extensor pollicis brevis tendon is normally small and may pass through a separate osteofibrous canal.

5. Though incision only of the stenosing tendon sheaths may be sufficient, thorough excision is more certain and does no harm.