1. Ectopic ossification is commonest in, but not confined to, traumatic paraplegia. It occurs also in many other neurological disorders which have in common a gross disturbance of spinal cord reflex activity. It is a true ossification and must be distinguished from calcification.

2. The neurological lesion may lie anywhere from the cerebral cortex to the mixed peripheral nerve. It may involve motor tracts, sensory tracts or a mixture of both.

3. The ossification is localised and self-limiting. It occurs mainly in the lower limbs and is restricted to certain muscles or muscle groups, the nerve supply of which is always below the level of the central neurological lesion.

4. The blood chemistry is usually normal.

5. A true arthropathy is rare except as part of a secondary suppurative arthritis.

6. The resemblance to myositis ossificans progressiva or to ossifying haematoma is only superficial, although the pathological process at cellular level may be the same.

7. The period of onset after paraplegia is variable. The earliest recorded example is in one of our own cases in which ossification occurred nineteen days after injury. Other patients have developed ossification after several years.

8. The condition is commonest in acquired nervous disease rather than in congenital disorders, and so far as we know it has not been described in the myopathies. The presence of muscular spasticity or flaccidity is relevant only in that it indicates a disturbance of reflex activity.

9. Soft-tissue ulceration appears to be frequently associated with ectopic ossification. The type of new bone formation associated with large chronic ulcers is not to be compared with the new bone formation in the muscles of a paraplegic patient in otherwise good general condition.

10. The occurrence of urinary tract infections with calculi and generalised sepsis is not specifically related to the onset of new bone formation.

11. Localised soft-tissue oedema often precedes the formation of new bone. Its appearance is undoubtedly important, but the mechanism of its origin is obscure.

12. It is not yet known what initiates ectopic ossification, what limits its spread and what finally causes it to stop.

13. We have described 100 examples of ectopic ossification in 603 paraplegic patients.

14. Surgery has been required in only eight patients. The only indication for surgery is bony ankylosis of the hip in an unacceptable position.

1. Paraplegia from fracture-dislocation at the thoraco-lumbar junction is a mixed cord and root injury. The root damage can be distinguished from cord damage by neurological examination and by comparison of the neurological level with the fracture level.

2. Even though the cord injury is complete, as it usually is, the roots often escape or recover.

3. Fracture-dislocations can be divided into stable and unstable types. Because of the possibility of root recovery care must be taken to prevent further damage to the roots by manipulation of the spine or during treatment. For this reason unstable fracture-dislocations are fixed internally by plates.

4. Internal fixation also assists in the nursing of the patient. The nursing technique and the care of the bladder are described.

A survey of this type cannot be used to point to any definite factor or factors predisposing to the development of hallux valgus. Nevertheless, a comparison of measurements in the morbid and control groups shows several outstanding differences:

1) There was a high degree of correlation between valgus and intermetatarsal angle in the two groups combined (coefficient, 0·7) but the correlation was higher in those cases with a degree of valgus greater than 25 degrees than in the remainder (coefficients, 0·36 and 0·53).

2) In the control group the first metatarsal was longer than tile second by a mean measure of 2 millimetres; in the morbid group by a mean measure of 4 millimetres. For a high degree of valgus and a low intermetatarsal angle the first metatarsal tends to be longer than the second by a significantly greater amount than when the high valgus is associated with iligh intermetatarsal angle.

3) In 90 per cent of the control cases there was a lateral displacement of the medial sesamoid of the first metatarsal of 3 degrees or less, whereas 88 per cent of the morbid group showed a displacement of 4 degrees or more. There was very little overlap in the distributions of this observation in the two groups. There was a high correlation between the degree of this displacement and the severity of hallux valgus.

4) Rotation of the hallux was not observed among the controls; in the morbid group those cases showing rotation had an average degree of valgus of 36 degrees while the rest had an average of 19 degrees. The mean degree of valgus in the morbid group was 32·0 degrees and that of the controls 15·5 degrees. The mean angle between the axes of the first and second metatarsals was 13·0 degrees in the morbid group and 8·5 degrees in the controls.

Since tile morbid group consisted largely of women (98 per cent) it is important to know that in the control group the only measure showing a statistically significant sex difference is that of intermetatarsal angle, but that, even so, the mean difference is only 1·3 degrees. Thus tile sex difference between the two groups is probably only of minor importance. The role of age in influencing the observations cannot be clearly elucidated from the data at present available. It can only be stated that there is no positive indication that age is a controlling factor in the departure observed in the morbid group from the control observations.