We report a series of 17 exchange arthroplasties for infected knee prostheses, ten one-stage and seven two-stage procedures. The method proved successful in controlling infection and restoring function. In two-stage exchanges the interval between the stages was managed by using a prosthesis as a spacer, and acrylic cement beads containing the appropriate antibiotic to provide high local concentrations. Three one-stage procedures had recurrence of infection, but were successfully treated by further exchange operations. All patients had satisfactory function and there have been no serious complications. We recommend this modified two-stage technique for the management of infected knee arthroplasties.

Postoperative anterior knee pain was evaluated in a consecutive series of 138 knees in 108 patients with rheumatoid arthritis treated by total knee replacement with Mark I Insall-Burstein prostheses. No knee had primary patellar resurfacing, and in the 119 knees followed up for a mean of 63.9 months, none had secondary resurfacing. Anterior knee pain was absent in 87 knees (73%), mild in 16 (13.5%) and moderate or severe in 16 (13.5%). The height of the patella above the prosthetic joint line was the only variable which was directly related to the incidence of anterior knee pain. The sensitivity and specificity of patellar height measurements for identifying patients with or without pain were derived. From these data, a selective policy of resurfacing the patella in those at risk was adopted. Choosing a patellar height of 15 mm or less, patellar resurfacing could be avoided in 80% of patients likely to have no pain, and the patella could be resurfaced in 65% of those likely to have anterior knee pain.

In a prospective study of 100 knee arthroplasties in patients with rheumatoid arthritis, simultaneous bilateral surgery was compared with staged bilateral replacements. All patients had improved function following their operations but those who had staged surgery only achieved maximum benefit after the second knee had been replaced. The complication rate was no greater for simultaneous surgery and we therefore advocate the method for those patients who require bilateral replacements.

The relationship between hindfoot deformity and forefoot pressure was assessed in 28 rheumatoid patients who had undergone forefoot reconstruction four years previously. Patients with valgus hindfoot deformities tended to have high forefoot pressures whereas those with a normal hindfoot recorded normal pressures on the dynamic pedobarograph. All patients with residual forefoot pain recorded abnormal forefoot pressures. We believe that orthotic control of hindfoot deformities should be considered for those patients who require forefoot surgery as a combination of surgical and orthotic management may offer the best chance of success.

Between 1970 and 1982, 50 total elbow replacements were carried out for rheumatoid arthritis using the Stanmore prosthesis. A long-term follow-up of the 44 elbows available for review is presented. Thirty-four of these (77%) had good results, five were fair, and five were poor. The complications and limitations are discussed.

Three amputated legs with tibial dysplasia were studied by radiography, arteriography and anatomical dissection. The radiographic appearances were the same as the Type 1b tibial dysplasia described by Jones, Barnes and Lloyd-Roberts (1978) in that the tibiae were absent but the lower femoral epiphyses were normal. However, our anatomical findings differed from those of Jones et al. since no bony or cartilaginous anlage of the proximal tibia was found in any of the three legs. The pattern of vascular anomaly was identical in the three legs and similar to the findings of Hootnick et al. (1980) in congenital short fibula. Congenital fusion of the subtalar joint was a constant finding. These results support the hypothesis that the arterial and skeletal systems are vulnerable to a teratogenic insult in the fifth week of embryonic life. The bony and arterial anomalies should be borne in mind by the surgeon attempting reconstructive surgery for this condition.

Seventy-eight patients who had been operated on for bony entrapment of lumbar nerve roots were studied in an attempt to define the clinical syndrome, and to assess the results of a new technique of decompression which preserves spinal stability. The mean age of the patients was 45 years and 28 of them had previously undergone spinal operations. Pain in the leg was the predominant symptom, with evidence of motor involvement in half of the patients. Signs of nerve root tension were found in only one-third of the patients. The principal factor in the aetiology was degenerative change in the posterior facet joints. Decompression was achieved by a partial undercutting facetectomy. Fifty-nine per cent of the patients obtained a "good" result and 85 per cent were satisfied with the result of their operation. Successful partial facetectomy for bony entrapment of lumbar nerve roots produced rapid and lasting relief of pain.

Thirty-one patients who had been treated surgically for lumbar spinal stenosis between 1968 and 1978 at the Norfolk and Norwich Hospital have been personally reviewed. In 28 patients (90 per cent) degenerative change in the lumbar spine had been the principal aetiological factor; the other three had idiopathic developmental lumbar spinal stenosis. In 17 patients (55 per cent) the result was classified as good, although a total of 26 patients (84 per cent) were satisfied. In patients with degenerative changes, one important reason for failure was inadequate decompression; re-operation in this group seemed worthwhile. The good results of operation for lumbar spinal stenosis were characterised by rapid resolution of pain in the leg.