The treatment of acromioclavicular injuries is controversial; few studies document the late results. We have reviewed 53 patients about five years after conservative management, in nine for subluxation and 44 for dislocation. Subjective and objective results were satisfactory in all cases except for one with painful subluxation, who was the only patient to change her occupation because of the injury. At review, joint stability was demonstrated by improvement in position and by the very small increase in the coracoclavicular gap on stress radiographs.

Unilateral Colles' fractures in 187 patients over the age of 55 years were studied in a randomised prospective trial: 97 fractures were minimally displaced and were treated either conventionally or in a crepe bandage; 90 displaced Colles' fractures were reduced and of these 47 were treated conventionally while 43 were encouraged to mobilise the wrist in a cast which restricted extension. Early wrist movement hastened functional recovery and led to earlier resolution of wrist swelling. Discomfort was no greater than in patients who were treated conventionally. The bony deformity, which recurred irrespective of the method of treatment, was not adversely affected by early mobilisation.

Sixteen consecutive patients with tibial plateau fractures were investigated by standard radiography, biplanar tomography and computerised axial tomograms (CT scans). It was found that CT scanning proved most helpful for classifying the type of fracture, for evaluating the degree of comminution, and for measuring displacement. Moreover, because a single position was maintained throughout the investigation, the patients felt less discomfort than during other assessment procedures. For these reasons CT scanning is recommended for evaluating this type of fracture.

Torsion and subsequent ischaemia is a well-recognised cause of symptoms and morbidity in general surgery. We present three cases of solitary pigmented villonodular tumours of the knee which were found to have undergone torsion. We believe these to be the first intra-articular tumours in which torsion has been reported.

Intra-osseous phlebography and the measurement of intramedullary pressure (IMP) have been used clinically and in experimental animals as qualitative methods of measuring blood flow in the bone. The normal phlebographic appearances in long bones are not clearly understood and the correlation between these appearances and the IMP is not known. The distal femora of 10 anaesthetised rabbits were cannulated percutaneously. The IMP was measured and phlebography performed by injecting a radio-opaque dye (Conray 280).The mean resting IMP was 33 millimetres of mercury with a range of 7 to 81 millimetres of mercury. The rate of elimination of dye from the marrow varied from less than 1 minute to 40 minutes. There was no correlation between the rate of elimination of dye and the IMP. Variation in the medullary phlebographic appearance and in the routes of drainage were noted. We concluded that the wide range of resting values for both techniques suggest that neither is a true measure of blood flow in the bone and that the results of research or clinical investigation using these techniques should be viewed with caution.

A group of patients were studied 10 years after stopping work in a high-pressure environment. Radiographs of their long bones showed little change during the period, but only two of 12 scintigrams were normal. The 10 abnormal scintigrams contained 18 "hot-spots" which were not always associated with an abnormal radiographic appearance; the findings suggest that some lesions may never become visible on a radiograph. A reactive or repair process associated with these lesions may be prolonged and may not be beneficial, as structural failure of the joint may subsequently occur. Prognosis should therefore be guarded.

In an attempt to explain the distribution of lesions of caisson disease of bone in the human femur, the regional distribution of circulating microspheres which had been labelled with scandium-46 was studies in the femur of the rabbit. Microspheres with a diameter of 15 microns were equally distributed between the two ends of the bone and between the upper and lower halves of the shaft. However, microspheres with a diameter of 50 microns congregated in the upper end of the femur and in the lower half of the shaft, the two sites most commonly affected by caisson disease. A large percentage of the microspheres in the shaft, especially the larger spheres, were retained in the marrow. It is suggested that the microcirculation of the marrow may act as a filter and that the nature and distribution of its vessels determine the site of impaction of circulating emboli. This would explain why lesions of the shaft mainly affect the medulla of the bone and not the cortex.

The early diagnosis of caisson disease of bone is hindered by the long delay which must elapse before an abnormality becomes apparent on a radiograph. The possible use of bone scintigraphy for this purpose was investigated. Necrosis of the bone and marrow was produced in rabbits by glass microspheres to simulate persistent gas-bubble emboli and then serial radiographs and scintigrams using 99mTc-diphosphonate were obtained. Regions of necrosis could be detected as "hot-spots" on the scintigrams as early as three weeks after the causative insult, which was many weeks before any abnormality could be detected on the radiographs. Histological examination of excised femora suggested that the scintigraphic abnormality might depend on the new bone formation during a reactive or repair process. It is suggested that scintigraphy may have clinical value in caisson disease.

This paper reports a detailed examination of three lesions of aseptic necrosis of bone occurring in a man who had worked in compressed air eleven years previously. Although two of the lesions were juxta-articular, in neither had the bone collapsed. Histology of only one similar lesion is reported in the literature (McCallum et al. 1966). Necropsy material is considered, together with radiographs and bone scans of the same lesions taken four years earlier. Similar changes have been shown to occur in commercial divers. On the evidence of this case it becomes clear that radiography is limited in its use and that bone scans as an indicator of repair may be open to misinterpretation. There may be a place for operation before the onset of symptoms in these cases of aseptic bone necrosis.