1. The literature on hyperextension injuries of the spine is briefly reviewed.

2. Such injuries in the cervical spine can be subdivided into five groups based on the pathological anatomy, based on the experience of fifty-one patients in the Spinal Injuries Centre for Victoria over the past five years.

3. Extension injuries of the thoraco-lumbar spine are discussed. They are rare and have a poor prognosis.

4. The importance of treatment based on sound clinical and pathological knowledge is emphasised, particularly in order that stable and unstable lesions may be recognised early and managed correctly.

1. That viruses may be involved in the causation of human tumours has long been suspected but not yet proved. The discovery that osteogenic sarcoma can be induced by viral agents in mice and hamsters makes the proposition that human sarcomas may also have a viral origin basically tenable on presently available evidence. In order to distinguish between passengers and causative agents it will probably be necessary to demonstrate antigenic cross-reactivity in tumours of similar type collected from different geographical areas, and the oncogenicity in subhuman primates of extracts containing virus from human tumours. Such information is likely to become available in the next few years.

2. The demonstration of tumour-specific immune reactions in an increasing number of patients with various forms of neoplasm, including skeletal sarcomas, and the correlation of these reactions with the clinical status of the disease sustains the hope that eventually immunotherapy may contribute to the control of cancer in man.

3. Animal experiments have revealed that the potentiation of immune responses may lead to the elimination of small foci of neoplastic cells. The role of immunotherapy in the treatment of cancer may therefore be as an adjunct to surgery, radiotherapy and chemotherapy (Alexander 1968). Once the primary tumour has been removed it may be possible to employ immunotherapeutic measures to destroy the relatively few remaining cells that give rise to late metastases; this is particularly apposite to juvenile osteosarcoma.

1. A study of fifty-nine patients with protrusion of the acetabulum showed that they fell into three age groups: those in their teens, those aged thirty-five to fifty years, and those presenting from fifty-one years onwards.

2. The juvenile age group was investigated clinically and biochemically but no causative metabolic factor was found.

3. The familial incidence was confirmed by radiological and biochemical surveys of several families.

4. The results of treatment show that when conservative treatment is insufficient a total hip replacement gives the best result from operation.

1. The literature of primary or idiopathic protrusio acetabuli is reviewed with particular reference to familial and racial influence on pathogenesis.

2. The radiological criteria of a "deep" acetabulum and of a "protruded" acetabulum are discussed.

3. Four generations of a family are presented in which all three members of the second generation showed marked protrusio acetabuli. In the remaining generations most members appeared to have abnormally deep acetabuli.

4. It is concluded that this family shows a strong familial tendency to deep or intruded acetabuli. The family tree, though incomplete, suggests a genetic influence ofa dominant type.

1. Eighty-nine cases of Perthes' disease are reviewed.

2. The prognosis varies with the amount of the epiphysis involved.

3. It is possible to assess the amount of epiphysial involvement by a study of the early radiographs. Cases were allocated to four groups on this basis.

4. It is confirmed that both sex and age at the time of diagnosis influence the final prognosis. The reasons for this are discussed.

5. The concept of "the head at risk" is suggested and radiological signs described to diagnose such cases.

6. It is hoped that the classification suggested may in future act as a basis for comparisons of treatment.

1. The duration of Legg-Perthes' disease seems somewhat shortened by abduction weightbearing plaster treatnlent. The average age of onset of our sixty patients at the start of this treatment was seven years nine months. The patients were treated in abduction plasters for an average of nineteen months.

2. The contour of the femoral head in relation to the acetabulum is better preserved than after our previous methods of treatment. We have evaluated our cases by the method of Mose, by the epiphysial index of Eyre-Brook and the epiphysial quotient of Sjovall, and by the centre/edge angle of Wiberg.

3. There was no undue influence on the growing epiphysis and no evidence of ligamentous strain.

4. With this type of protected weight-bearing, the patients were kept active when both hips were affected.

5. No patient with unilateral disease showed Legg-Perthes' changes on the opposite side while under treatment or at follow-up.

6. The children were able to be at home and to attend school.

1. A retrospective clinical and radiological study has been undertaken of forty-six cases of closed Dupuytren fracture-dislocation of the ankle joint in adults.

2. The final results are analysed with reference to the methods of treatment employed.

3. The problems of this injury are discussed referring both to the results of this investigation and to the past literature.

1. Osteogenesis imperfecta is characterised by osseous fragility. Patients with the "congenita" form have multiple fractures before birth; those with the "tarda" form have osteoporosis, and develop multiple fractures and milder deformities of long bones at varying times after birth.

2. The frequency of blue sclera, dentinogenesis imperfecta, bruising, ligamentous laxity, and deafness are recorded in sixty patients seen at the Hospital for Sick Children, Toronto, from 1949 to 1969. The major orthopaedic deformities of long bones were antero-lateral bowing of femur and anterior bowing (sabre shin) of tibia.

3. The incidence of scoliosis (40 per cent) is high in osteogenesis imperfecta. Two patients, one in Toronto and one in Seattle, have had Harrington instrumentation and fusion for this.

4. Fractures were commonest in the femur and tibia and few in the cervical spine and femoral neck. There were four cases of disturbing hyperplastic callus formation.

5. Twenty-one patients were operated on for long bone deformities and recurrent fractures by the Sofield technique. Despite extensive subperiosteal dissection non-union is rare (four cases). Fourteen of twenty-one patients so treated are able to walk, with or without assistance. Surgical intervention to both correct and prevent deformities is justified.

6. Patients with osteogenesis imperfecta compensated for their disability by reasonable academic achievement and by choosing a sedentary occupation.

1. After exclusion of the well known causes of torsion such as congenital dislocation of the hip, Legg-Perthes' disease, cerebral palsy and congenital talipes equinovarus, examination of 1,320 nearly normal children disclosed an incidence of 13·6 per cent toeing-in or toeing-out.

2. There was a female preponderance of seven to three on presentation decreasing to four to three in uncorrected cases.

3. There was persisting upper femoral torsion of greater than 10 degrees in two-thirds of all cases of toeing-in whether corrected or uncorrected.

4. When correction of toeing-in occurred it took place between four and seven years of age, but mainly at five years.

5. There was a normal angle of anteversion in one-third of children whose toeing-in was not corrected. This suggests the possibility of acetabular maldirection.

6. Uncorrected torsional stresses may play a part in the later development of osteoarthritis.

1. Thirty-four cases of calcaneal osteotomy for mobile flat foot in nineteen patients are reviewed.

2. The function was markedly improved in seventeen of the nineteen patients.

3. The operation was successful in correcting the valgus deformity of the heel in thirty of the thirty-four feet. it was less successful in improving the longitudinal arch, especially when the flat foot deformity was severe.

1. A seven-generation family is described which presented an autosomal dominant hereditary disorder characterised by brachydactyly, hypoplastic nails from the index to the little fingers, normal toe nails, absent middle phalanges in the fingers and lateral four toes, variable degrees of hypoplasia of the distal phalanges in the fingers with normal thumbs and normal big toes.

2. Less frequently syndactyly between middle and ring fingers on the left and narrowing of the proximal phalanges of the ring and little fingers are also found.

3. This disorder seems to represent a new hereditary syndrome.

1. A case of arteniovenous fistula within the tibia of a girl is described.

2. Removal and replacement of a large part of the tibial diaphysis was followed by "re-formation" of the bone.

3. The literature of the condition is reviewed.

A case is reported of fracture of the tibia in a haemophiliac, complicated by severe ischaemia. Extensive decompression of the limb followed later by skin grafting was required. The haematological management which made such surgery practicable is described. It involved the use of cryoprecipitate for a period of seven weeks.

1. Six patients are reported in whom ischaemic muscle contractures followed prolonged external pressure.

2. Systemic hypoxaemia may be a predisposing factor in patients with overdoses of central nervous system depressants.

3. If treatment is to be successful, early diagnosis is required, and the most important factor is an awareness of the condition.

4. The treatment of the late case is discussed.

1. Grafts of joint cartilage from immature lambs were used to repair articular cartilage defects in other lambs and in adult sheep.

2. Stability of these grafts in a functional state was found in most for periods up to fourteen months. Although a limited homograft reaction occurred this did not lead to destruction of the cartilage, even though parts of it were well vascularised.

3. The results suggest that the process of endochondral ossification is associated with the liberation of antigenic material leading to sensitisation of the host. Destruction ofthe cartilage is prevented by an inhibitory action which the matrix appears to exert on the destructive elements themselves and which is itself dependent on the vitality of the chondrocytes.

4. The avascularity of cartilage is not a sufficient explanation for its privileged position in relation to the homograft reaction.

1. Thirty-seven specimens of the proximal third of the human femur were subjected to cyclically varying loads applied in a physiological direction to the femoral head, having maximum values of from four to thirteen times body weight.

2. Ten of these specimens sustained subcapital fractures of the femoral neck after numbers of cycles of loading varying from 123 to 8,193.

3. The maximum value of cyclic load needed to give fatigue fracture after 10,000 or fewer cycles was found to vary from about twelve times the body weight at ages twenty to fifty to about five times the body weight at age seventy or more.

4. In youth and in middle age the load levels mentioned above are greater than those encountered in normal living, but are comparable to those which may be applied to the femoral head during activities known to produce "fatigue" fractures clinically in young adults.

5. In the elderly the load levels mentioned above are within the range that can be applied in normal living. It is inferred that some femoral neck fractures in the elderly may be fatigue fractures caused by the cyclic loading of normal walking.