The causes of persistent symptoms after meniscectomy have been assessed clinically, radiologically and arthroscopically in 174 knees. The commonest finding was early degenerative arthritis (chondromalacia) of the femoral condyle (40 per cent). Retained fragments of meniscus were less common than expected (13 per cent), and lesions of the other meniscus were rare (5 per cent). The clinical diagnosis was altered in 42 per cent by arthroscopic examination. Arthroscopy was found to be a valuable technique in this group of patients with problems of diagnosis.

A study has been made of 800 consecutive arthroscopic examinations of the knee with special emphasis on the changes in management that resulted. Of 614 knees that would have been operated upon if arthroscopy had not been available, open operation was avoided in 32 per cent, a different operation was done or planned in 27 per cent, and there was no important change in the remaining 41 per cent. Of 186 knees that would have been treated conservatively if arthroscopy had not been available, the examination resulted in some immediate benefit to 30 per cent of the patients. There were no wound infections after arthroscopy alone, and the known incidence of incorrect interpretation was 1.4 per cent.

One thousand and forty-two McKee-Farrar prostheses of the present design inserted in Norwich from January 1965 to December 1972 have been reviewed retrospectively to determine the incidence of complications needing revision. Of prostheses implanted for more than two years, 6.6 per cent needed revision for loosening (cup 35 per cent; stem 2.2 per cent; both components 0.9 per cent). Of the total number, 2.3 per cent became infected and 1.9 per cent dislocated. Most dislocations needed only a single closed reduction but 08 per cent were revised. The outcome of revision operations was also assessed. Of revisions for loosening, 40 per cent needed no further operation but 23 per cent required excision; pelvic fracture or bone destruction around the components made success unlikely. Revisions for dislocation were disappointing. Of all revisions 17 per cent became infected. Excision arthroplasty is better than a series of failed revisions in an elderly patient.

1. Forty-six cases of congenital spondylolisthesis (Newman's Group 1) have been studied. The diagnostic criteria were lumbo-sacral subluxation, deficient development of sacral neural arches and superior facets, and attenuation and elongation of the pars interarticularis, with or without a defect in continuity.

2. Intertransverse lumbo-sacral fusion is a safe and reliable method of treatment.

3. Stabilisation is not complete before two years.

4. Spinal fusion is indicated in all patients with significant symptoms during the period of growth, but in adult patients only if conservative treatment fails.

1. Eight patients are described in whom the patellae subluxated laterally on every extension of the knee. This is an unusual type of recurrent subluxation. It may recover completely, or remain symptom-free for many years, or increase in severity so that the patient seeks treatment for relief of pain and joint effusion, or progress to frank dislocation.

2. Each patient was examined and the probable causes were analysed. The bayonet deformity was present in twelve of the sixteen knees. A new observation is made on the relationship of tibial crest and tubercle in this condition.