1. Hemiarthroplasty is a method of dealing with painful deformities of advanced osteoarthritis and rheumatoid arthritis of the knee.

2. The indications and contra-indications for this procedure are discussed. Careful selection of patients is essential.

3. The technique of operation and management after operation are described.

4. The results of such a procedure, as done by one surgeon, are given. Good results have been obtained in 80 per cent of the osteoarthritic knees and in 69 per cent of the rheumatoid knees.

5. The complications, place of associated operations and value of revision procedures are discussed.