1. The indications for correction of severe rigid kyphosis by lumbar osteotomy are described.

2. The fatal complications in a series of a hundred cases are listed. With more experience of this operation they should be considerably reduced.

3. Among the non-fatal complications the low incidence of recurrence of the deformity severe enough to require further operation is noteworthy.

1. In this series of 150 cases of arthritis of the hip joint treated by vitallium mould arthroplasty (182 arthroplasties), 80 per cent. of late results are satisfactory to both patient and surgeon.

2. Striking features are the relative painlessness, smooth hip joint movement, progressive improvement in function, and reformation of the joint lines as seen radiographically in the post-operative period.

3. Function after arthroplasty for traumatic and degenerative arthritis approaches the normal hip joint much more closely than in cases of infective and rheumatoid arthritis.

4. There is a complete absence of low back symptoms or postural difficulties, and there is no difficulty in preventing stiffness of the knee joint.

5. Different technical procedures are indicated according to the degree of absorption of the femoral head or neck, and the stability of the mould in the acetabulum.

6. The operative mortality rate in this series was nil, and during the six-year follow-up period only one case died as the result of a complication of the arthroplasty.

7. In addition to meticulous operative technique and the use of special instruments, the importance of careful and prolonged after-treatment must be stressed.

8. It must also be emphasised that secondary operative revisions are often necessary, particularly in cases of infective and rheumatoid arthritis.