1. A description is given of historical discoveries relating to intermittent claudication. Various theories that have been advanced are discussed. A hypothesis, based on the work of Lewis, is elaborated.

2. A classification of obliterative arterial disease is outlined. The three groups that are distinguished are: primary thrombosis of the popliteal artery; juvenile obliterative arteritis; and senile obliterative arteritis.

3. The methods adopted for assessment of the severity of disease, including study of the clinical features, arteriographic findings, results of novocain infiltration and examination of the patient on a walking machine, are reported.

4. Methods of treatment by Buerger's exercises, contrast baths, intermittent venous occlusion and suction pressure; by lumbar ganglionectomy ant paravertebral block with phenol; by vitamin E (α-tocopherol) therapy; by treatment with thiouracil antistin; by internal popliteal myoneurectomy and division of the external popliteal and posterior tibial nerves; and by tenotomy of the tendo Achillis, are discussed.

5. It is concluded that tenotomy of the tendo Achillis should replace myoneurectomy in Type 3 cases where the blood supply is so far reduced that vascular stability cannot be achieved, and that it might apply in Type 2 cases in which there is persistent pain at a steady level.

6. The results of treatment in 276 patients with intermittent claudication are recorded.

1. Biopsies of muscle were taken during the course of operation from sixteen patients with vascular injuries to the limbs. Three types of histological change were found.

2. In the first, there was massive necrosis of muscle fibres—a group of cases in which there had always been serious damage to the main artery of the limb or to the vessel supplying the affected muscles.

3. In the second type there was dense interstitial fibrosis, the muscle fibres sometimes being normal and sometimes showing necrosis or denervation—a group of cases in which the vascular injury varied from severance of the vessels by gunshot wounds to trivial damage, causing slow haemorrhage within fascial-bound spaces.

4. The third type showed scattered foci of necrosis together with patchy interstitial fibrosis—due to the pressure of tight plasters, crushing of the limb, fractures with arterial contusion, or slow haemorrhage or extravascular transfusion within fascial planes. The rise of tension within the muscles was probably sufficient to occlude the smaller arterioles with resultant patchy necrosis.

5. The vulnerability of certain muscles to vascular damage is partly related to the intramuscular vascular pattern, of which five types have been described.

6. In ischaemic muscles the intramuscular nerve trunks may be normal or they may show evidence of degeneration or necrosis; but in favourable circumstances there may be regeneration of axons.

7. In some cases there was evidence of regeneration of muscle fibres in man, the regeneration being dependent to some extent upon the efficiency of intramuscular anastomoses.

8. The prognosis, in cases of ischaemia of human voluntary muscle, depends upon the extent and the reversibility of damage to both muscle and nerve fibres and upon the extent of regeneration of muscle fibres.

1. A case of solitary plasmocytoma of the thoracic part of the spine, verified by necropsy, is described.

2. A brief review is given of eighteen acceptable cases of solitary plasmocytoma of bone.

3. Of the eighteen patients, fifteen were men; the five spinal tumours were all in men.

4. Diagnosis requires: a) biopsy identification of plasmocytoma; b) exclusion of the possibility of generalised myelomatosis by complete radiography of the skeleton, repeated if necessary at intervals during the ensuing two or three years or longer.

5. A tumour of brief duration, proved to be solitary by careful necropsy, cannot be placed with certainty in the group of truly solitary plasmocytomas; it might have been a precocious first lesion of myelomatosis.

1 . A series of 166 fractures and fracture-dislocations of the dorso-lumbar spine has been reviewed.

2. A new method of classifying these injuries is suggested.

3. A type of fracture with lateral wedging, previously unidentified, which has certain distinctive clinical and anatomical features is described.

4. The factors responsible for redisplacement are discussed and it is considered that in most cases this is predictable from the outset.

5. At the present time orthodox treatment is based on the assumption that a perfect anatomical result is indispensable to a perfect functional result. Analysis of the results in the series now reported shows that there are no grounds for this assumption.

6. Treatment is discussed in the light of the foregoing conclusions. This is based on a division of cases into stable and unstable types, the recognition of which is of crucial importance.

1. A case of fracture-dislocation of the atlas on the axis is presented in which the neck had been manipulated under anaesthesia for "rheumatism."

2. Despite marked displacement there were no important neurological complications.

3. One-stage reduction by traction was carried out very slowly and with radiographic control. It is believed that this is less distressing to the patient, and safer, than gradual reduction by prolonged traction.

4. Because of the instability of the atlanto-axial joint after reduction surgical fusion of the upper cervical spine to the occipital bone is advisable.

5. In the case now reported recovery was complete.

1. In a series of one hundred personal cases of "painful shoulder" rupture of the musculotendinous cuff was proved by operation in eighteen cases and was presumed in eight further cases, namely, in about one quarter of the series.

2. Of the eighteen cases treated by operation through the transacromial approach, perfect results were obtained only in four. The other results were unsatisfactory. In five, movement was good but there was pain or weakness of the limb. In nine the condition was unaltered or made worse.

3. Conservative treatment of traumatic lesions of the supraspinatus tendon is therefore advocated. The advisability of rest of the shoulder joint in an abduction splint for five or six weeks is stressed. Operative exposure, through a transacromial approach, is recommended only when conservative measures have failed.

4. When there is rupture of the cuff there is evidence that simple longitudinal suture of the gap after freshening of the margins is likely to give better results than attempts to suture the medial end of the rupture to the greater tuberosity. Most ruptures have a longitudinal extension of the initial transverse tear, and direct suture of the medial edge of the gap to the greater tuberosity may lead to shortening of the tendon and interference with its function.

5. Ruptures of the supraspinatus tendon may cause no symptoms, lead to complete loss of function, or cause a painful arc of movement during mid-elevation. The clinical state depends upon whether or not the condition of the ruptured tendon is causing pain, and whether the other short rotator muscles of the shoulder can compensate in tensor and fixator actions for the loss of action of the supraspinatus.

6. Capsulitis is a convenient term by which to describe inflammatory lesions of the capsule and bursae around the shoulder joint. The initial stage of irritative capsulitis may develop to the later stage of adhesive capsulitis. Differentiation is important because treatment in the first stage is by rest, and in the second by manipulation and exercise.

7. The subdeltoid bursa is the "peritoneum" of the spinatus tendons; like the peritoneum it shares the pathology of the organs it protects and is itself seldom the site of primary pathological processes.

8. The management of the "frozen shoulder," whether loss of movement is protective or adhesive, calls for time and patience but the ultimate outlook is good.

1. Degenerative lesions of the shoulder joint can often be demonstrated radiographically before there is actual rupture of the musculo-tendinous cuff.

2. The characteristic pathological, clinical and radiographic features of degenerative lesionsare described.

3. All injuries of the shoulder joint, however trivial, occurring in patients over middle age, should be studied carefully by radiographic examination.

4. In injuries of the shoulder joint the presence of a degenerative lesion prolongs the duration of symptoms, and the prognosis is less satisfactory than when there is no radiographic evidence of abnormality.

1. The end-results of conservative treatment of supraspinatus tears have been studied in a series of 109 patients graded on a clinical basis, and in a further series of twenty-seven patients assessed initially by procaine infiltration.

2. In 87 per cent. of patients with mild lesions, full function was regained in an average period of five and a half weeks. In more than 50 per cent. of patients with apparently severe lesions, there was full functional recovery in eleven to thirteen weeks.

3. Clinical assessment, other than as mild or apparently severe, is unreliable in the early stages.

4. Procaine infiltration of recent tears, by abolishing pain and spasm, allows more accurate assessment of supraspinatus function and gives a more clear indication as to the advisability of conservative or early operative treatment. If such infiltration of the torn segment of tendon fails to restore voluntary abduction power, early operative repair is indicated.

5. Six patients with negative procaine tests, in whom the shoulder cuff was subsequently explored, all showed extensive tears.

1. The "frozen" shoulder syndrome is due to an inflammatory lesion in the musculotendinous cuff invoked by a local area of degeneration.

2. The available evidence suggests that the primary site of the degenerative lesion is in the supraspinatus tendon.

3. Other causes of shoulder pain which must be differentiated from "frozen" shoulder are peritendinitis of the long head of biceps, degeneration or tears of the supraspinatus, and calcified deposits in the supraspinatus.

4. An explanation of the pathogenesis of lesions of the musculo-tendinous cuff is submitted in which the different types of clinico-pathological syndrome are correlated. This hypothesis is in accord with the experimental, clinical and operative findings.

1. The explosive type of painful shoulder due to rupture of a calcified deposit into the sub-deltoid bursa is described.

2. A brief report of six cases is presented.

3. No treatment other than rest and sedation is needed.

1. The supraspinatus group of lesions constitutes one of the two common causes of the painful shoulder.

2. Most, but not all, of these lesions resolve either spontaneously or after conservative treatment.

3. When conservative treatment fails symptoms can be relieved by excision of the acromion process, provided that sufficient bone is removed to relieve all pressure on the tendon throughout a full range of shoulder movement.

4. Excision of the acromion is contra-indicated if there is doubt as to the diagnosis or if there is true limitation of shoulder movement.

One of the aims of this work was to find criteria by which the quality of bone as a supporting tissue might be judged. This inevitably involves discussion and, if possible, assessment, of the relative importance of the inorganic and organic material of the bone. It is relatively easy to measure the mineral content, and for that reason it has always received more than its due share of attention.

In the present experiment the composition of the ash of all bones was remarkably constant, with a Ca/P ratio of 2. Furthermore, X-ray crystallography showed that the structure of the inorganic material was the same in all cases. The great difficulty of measuring variations in the quality of the organic material which is, of course, protein in nature makes it impossible to say how much it influences bone strength. Since at least 40 per cent. of the bone is collagen, either a quantitative or a qualitative alteration might alter bone strength. X-ray crystallography revealed no qualitative differences in the collagen material of bones of the three groups; so that for the present it would seem safer to assume that alterations in the physical properties of the bones are due to variations in the relative proportions of organic and inorganic constituents (Dawson 1946, Bell et al. 1947).

These experiments show that the three diets produce highly significant differences in the percentage of ash, in S_B, and in E. It is possible that some variations in the percentage of ash are due to variations in the absolute collagen (weight of collagen in unit volume of bone substance); but the range of variation in the percentage of ash leaves no reasonable doubt that differences in percentage ash between the diet groups are due essentially to differences in absolute ash. Presumably the collagen contributes something to the strength of the bone; but the indications are that it plays a minor part and that the relative weakness and flexibility of rachitic bones is due to decrease in the absolute ash content. Within any one diet group, the relation between percentage ash and the other two variables, S_B and E, is masked by other sources of variation such as those associated with the many measurements involved; and thus the correlation between percentage ash and S_B, and also between percentage ash and E, is not significant.

At first sight, the scatter diagrams (Figs. 5 and 6) appear to indicate a correlation between ash and S_B, and between ash and E. Closer inspection shows, however, that the apparent trend is due largely to differences between the means of the diet groups, and that the points within any one group show no such obvious trend. Figure 7 shows that the position with regard to correlation between S_B and E is very different. Here there is an obvious trend within each diet group; the amount of scatter is very much less. Calculation shows that, even when the differences between the means of diet groups is excluded, there is still a significant correlation between S_B and E. The question of the correlation between the three variables is discussed more fully in the addendum to this paper.

Although the "goodness" of a bone is usually judged by its breaking stress, the experimental findings recorded above suggest that it may be assessed equally well on the basis of elastic properties as shown by Young's modulus. Normal bones, group S in these experiments, were elastic up to 79 per cent. of their breaking stress (Table II): the poorer bones of groups R and N were, however, only a little inferior in this respect. In some cases there was no apparent deviation of the load-deflexion curve from a straight line until the bone was about to break. Such a curve was published in the first paper of this series (Bell, Cuthbertson and Orr 1941), but in the light of further experience this curve is scarcely typical. The terminal falling over of the curve is illustrated in Figure 4 and is much more marked in the bones of group R.

While stress at the upper limit of elasticity varies over a wide range in the three groups (Table II and Fig. 4), the strain at this point is remarkably constant at about 1·5 per cent. This same percentage displacement must occur between the molecules of the bone material at the elastic limit—and it may be that, up to this amount of molecular displacement, the deformation is reversible; but that beyond it, plastic changes occur. We have no evidence as to whether the limiting displacement concerns mineral or protein constituents of the bone, or both.

We have already commented on the remarkable strength of bone material (Bell et al., 1941). The breaking stress of normal rat bone is about the same as that of cast iron, and about half that of mild steel. Young's modulus, however, is only one-tenth that of cast iron and one-twentieth that of steel. Thus bone, despite its lightness (specific gravity about 2·5 as compared with 7·9 for iron), is remarkably strong and at the same time more flexible than might be expected. Presumably the biological advantage is that greater flexibility helps to absorb sudden impacts. It is unusual in metallic substances to find the elastic modulus proportional to the strength; this is more characteristic of materials like concrete and timber. Another remarkable property of bone is that it remains elastic up to three-quarters of the breaking stress. Most metals show considerable ductility before reaching their breaking point.

While Young's modulus is of interest, both on its own account and as an index of the quality of the bone, its close association with breaking stress suggests that it might be used to predict the maximum load which a bone can carry safely. Since E, unlike S_B, can be measured without damage, useful information might be gained by measuring the elasticity of living human bones.

1. Three groups of one month old rats were fed for a period of four to five weeks on a rachitogenic diet (group R), the same rachitogenic diet with vitamin D (group N), and a complete diet (group S).

2. Young's modulus of elasticity E for bone can be derived from measurements of the deflexion of the centre of a femur loaded at the centre and supported at its ends.

3. The three different diets produced significant differences in breaking stress S_B, Young's modulus E, and percentage ash in the bones. It has not been shown conclusively that higher ash content alone is responsible for the greater S_B and E values of bones produced on the better diets.

4. The value of E in group R was 0·6 x 10⁶ lb./in.²; in group N 1·0 x 10⁶ lb./in.²; and in group S (which can be taken as normal) 1·6 x 10⁶ lb./in.².

5. There is a high correlation between S_B and E even when the effect of diet is eliminated.

6. Although the bones produced on the good diet (group S) were much stronger than those of groups N or R, the strain at the elastic limit was the same (about 1·5 per cent.). The strain at rupture tended to be higher in groups N and R than in group S.

7. The properties of bone as a structural material are discussed.