We describe a case in which chronic oedema of a leg was due to pressure on the external iliac vein from an intrapelvic rheumatoid cyst. Ultrasound and CT scanning gave the clues to diagnosis.

We have reviewed 106 patients after treatment for spontaneous rupture of the calcaneal tendon, and assessed the clinical results including the power of plantarflexion. In patients treated within 48 hours of injury the result was very similar in conservatively and in operatively treated patients. The incidence of major complications was higher after operation (17%) than in those treated conservatively (4%). Patients who were treated more than one week after injury, however, had an inferior result with respect to power of plantarflexion after conservative management. It is therefore recommended that calcaneal tendon rupture is treated conservatively with a plaster in full equinus when it is diagnosed within 48 hours of injury, and by operation when diagnosis has been delayed for more than one week.

Three cases are reported in which an osteosarcoma developed in relation to an enchondroma in a long bone. Two of the cases were in the proximal femur whilst one occurred in the proximal humerus, both recognised sites for old calcified enchondromas or "cartilage rests". The ages of the patients at presentation were 55, 63 and 84 years and all were women. Two patients died with pulmonary metastases within six months of the onset of clinical symptoms. Despite their intimate relationship to the enchondromas, none of the osteosarcomas could be shown histologically to have arisen from tumour cartilage. It appears probable that these are cases in which independently arising tumours have merged to form a so-called "collision" tumour, but the possibility that they could have been derived by dedifferentiation of a previously benign neoplasm cannot be discounted.

The value of remanipulating a Colles' fracture which has redisplaced after primary reduction was assessed in 50 patients. In those over 60 years old, remanipulation failed to achieve a lasting improvement in position, while the majority of those under 60 years maintained a significant improvement in dorsal angulation. It is concluded that the elderly patient does not benefit from this procedure.

Two cases of aneurysmal bone cyst in the pelvis which healed spontaneously are described. Spontaneous regression of aneurysmal bone cysts has not previously been well documented. Our experience with these two cases suggests that radical intervention is not always necessary.

In 30 elderly women awaiting hip arthroplasty on account of unilateral osteoarthritis of the hip, walking speed and oxygen consumption were measured during a 12-minute test and the power output was calculated from the stair climbing rate. The results were compared with those for a group of 30 normal women of similar age. An age-related decline in maximal walking speed was observed in both groups. After arthroplasty there was a significant increase in maximal walking speed, particularly among the more disabled patients, with the major gain occurring by three months and a further slight increase by six months. Oxygen consumption returned towards normal values, and both stride length and cadence increased by a comparable degree. Mean power output during stair climbing doubled, and both before and after arthroplasty bore a linear relationship to the maximal walking speed.

Using bone decalcilied with 0.6 N hydrochloric acid as an inducing agent, the inductive capacity of different soft tissue sites was investigated. Muscle and fascia regularly permitted the induction of bone, while spleen, liver and kidney suppressed bone induction. Bone formation could be induced in these organs if living autologous fascia was implanted together with the inducing agent; while bone formation was inhibited when living autologous spleen tissue was implanted with the inducing agent to normally favourable sites. The administration of systemic heparin and the diphosphonate ethane-1-hydroxyl, 1-diphosphonic acid (EHDP) suppressed bone induction.

It is suggested that for bone induction to occur in soft tissues, three conditions must be present: 1) an inducing agent; 2) an osteogenic precursor cell; and 3) an environment which is permissive to osteogenesis. The presence of osteogenic inhibitors in spleen, liver and kidney is postulated.

1. Using the incidence of hip fracture as an indication of senile osteoporosis, the occurrence of this disease is found to vary greatly in different racial groups. The highest reported incidence is in Sweden, followed by Britain, Hong Kong Chinese, Singapore Chinese and South African Bantu, in that order. Likewise, the sex incidence varies, women outnumbering men in Sweden and Britain, men exceeding women in Singapore; an equal sex incidence is found in Hong Kong.

2. In all races and in both sexes the incidence is more closely related to age than any other factor, a progressive increase being noted after forty-five. Ageing is clearly the dominant etiological factor, but this does not explain the different racial incidence. These differences cannot be attributed to hormonal state or to the dietary intake of calcium, but do accord in general with the living standards of the different countries and the degree of physical activity undertaken by the different populations and sexes.

3. Hereditary factors may play a part, but further geographical study of the incidence of senile osteoporosis is necessary before the relative importance of inheritance and environment can be assessed.

1. Sixty-one cases of compression of the ulnar nerve are reported, forty at the elbow and twenty-one at the wrist. Although contributory factors may include deformity, osteoarthritis, injury, ganglia and other tumours, the narrow anatomical confines of the nerve at these two levels are noteworthy and alone may produce nerve compression.

2. Careful clinical examination will usually determine the level of involvement if not the exact pathology. Surgical exploration is indicated both as a diagnostic and therapeutic procedure in most cases.

3. Following removal of the compressing agent rapid recovery occurred in most cases.

1. The clinical features, diagnosis and treatment of osteomalacia are discussed in relation to thirty-seven recently recognised cases. It is suggested that this disease is not uncommon in elderly women, among whom it is liable to be confused with senile osteoporosis. Osteomalacia may be distinguished by, firstly, the history, in which persistent skeletal pain of long duration and muscular weakness are typical of osteomalacia, but not of osteoporosis in which transient episodes of pain usually associated with a fracture are more characteristic. There is a high incidence of previous gastric surgery in the osteomalacia patients. Secondly, the physical examination shows skeletal tenderness in osteomalacia but this is not a particular feature of osteoporosis. A shuffling "penguin gait" suggests osteomalacia. Thirdly, the biochemistry shows a low plasma calcium and phosphate, and raised alkaline phosphatase levels commonly in osteomalacia but these are usually normal in osteoporosis. Reduced twenty-four-hour urinary calcium is characteristic of osteomalacia but not of osteoporosis. Fourthly, radiology will show diminished bone density which is common to both diseases, but if the changes are more marked in the peripheral bones than in the axial skeleton osteomalacia is suggested; the opposite is typical of osteoporosis. Skeletal deformity without fracture suggests osteomalacia, as do stress fractures and greenstick fractures in the elderly. Looser's zones are diagnostic of osteomalacia in which they are the most important radiological feature. Finally, histology will show the presence of excess osteoid tissue in undecalcified sections of bone in osteomalacia. This may be the earliest and most sensitive index of the disease and biopsy is indicated in all doubtful cases.

2. The etiology is discussed and it is suggested that a dietary deficiency of vitamin D, limited exposure to sunlight and mild degrees of malabsorption may all be important either alone or in combination. No satisfactory explanation is offered for the predominant female incidence.

3. A practical method of treatment is given and the dangers of uncontrolled administration of vitamin D indicated.

4. Treatment of osteomalacia is rapidly and consistently successful, and well justifies a thorough screening of all elderly patients presenting with weakness, skeletal pain, pathological fractures or with diminished radiographic density of bone.

1. Homografts of eighteen-day-old foetal femora in pure strains of mice showed no fundamental difference in behaviour from grafts of more mature bone and cartilage.

2. Growth of bone was limited to a short period after transplantation and was abolished by previous immunisation. Cartilage growth alone was responsible for the increase in size of these transplants and did not appear to be influenced by the presence of immunity.

3. There is no reason to suppose that bone from an immature source is likely to behave more favourably than more mature bone homografts in clinical use.

4. The limited growth of cartilage and the total failure of bone survival in the heterografts indicate an immune reaction ofa different order from that which develops against the homograft.

5. The different effect of the homograft immune reaction on cartilage and bone enabled certain conclusions to be drawn concerning the part played by these two tissues in determining the form of a bone. Cartilage growth and development is shown to be regulated in large part by intrinsic factors. Bone growth and form on the other hand is shown to be dependent largely upon extrinsic influences.

1 . Fresh bone autografts to a muscle bed in the rat gave rise to vigorous new bone formation from about the fourth day. The graft took the form of a hollow ossicle with central bone marrow at eighteen days: it became progressively more regular in outline and was still present at six months.

2. Fresh bone homografts produced two separate phases of new bone formation–early and late. In the early phase non-lamellar woven bone appeared at about the fourth day, continued to grow until eight days, and subsequently died. It arose from osteogenic cells of the homograft. In the late phase, which developed in relation to a few grafts after four weeks, the new bone was lamellar in character, and remained closely applied to the graft surface. Evidence is presented that this bone arose by metaplasia of the host connective tissues at the graft site. There was a local inflammatory response to the bone homograft.

3. Both phases of homograft new bone formation were abolished if the animal was prepared by a skin homograft from the same donor four weeks before, but not if four months elapsed between the two grafting procedures.

4. Freeze-dried bone homografts did not give rise to the early phase of homograft new bone but produced a few examples of the late phase after five months. The inflammatory response was less intense with freeze-dried homografts than with fresh homografts.

5. Skin homografts three weeks after fresh bone homografts from the same donor underwent an early rejection at five to six days.

6. Skin homografts three weeks after freeze-dried bone homografts from the same donor had a mean survival time of twelve days, which was significantly longer than the mean survival time of l0·9 days in normal rats.