Sex hormones play important roles in the regulation of the proliferation, maturation and death of chondrocytes in the epiphyseal growth plate. We have investigated the effects of male castration on the cell kinetics of chondrocytes as defined by the numbers of proliferating and dying cells. The growth plates of normal rabbits and animals castrated at eight weeks of age were obtained at 10, 15, 20 and 25 weeks of age. Our study suggested that castration led to an increase in apoptosis and a decrease in the proliferation of chondrocytes in the growth plate. In addition, the number of chondrocytes in the castrated rabbits was less than that of normal animals of the same age

Relating the results of our investigations to the knowledge hitherto acquired about the etiology of osteoporosis (which I have already referred to), I am inclined to interpret the pathogenesis of osteoporosis in the following way: 1) Primary osteoblastic deficiency: congenital (Lobstein); involutive (senile osteoporosis?); 2) Reduced osteoblastic activity from absence of trophic stimuli: (inactivity, ovarian agenesia, eunuchoidism, menopause); 3) Reduced osteoblastic activity from inhibitory stimuli: (cortisone, adrenocorticotrophic hormone (A.C.T.H.), stress, Cushing's disease, thyrotoxicosis); 4) Normal osteoblastic activity but insufficiency of constructive material: (malnutrition, disturbances of the digestive system, insufficiency of vitamin C, diabetes, thyrotoxicosis, cortisone, A.C.T.H., stress, Cushing's disease). Osteoporosis may therefore be the consequence either of a congenital osteoblastic deficiency, such as that found in cases of osteogenesis imperfecta, or of reduced osteoblastic activity due to absence of trophic stimuli such as mechanical stress and the sex hormones, or of reduced activity of the bone cells due to anti-anabolic substances which inhibit them, such as cortisone and its derivatives and the thyroid hormone in strong doses, or lastly of reduced availability of construction material due to its introduction in reduced quantities (starvation, dysfunction of the digestive system) or due to hindering of synthesis (deficiency of vitamin C, diabetes, cortisone and its derivatives) or due to an excessive degree of destruction (thyrotoxicosis). In the case of anti-anabolic hormones from the adrenal cortex, the mechanism may thus be twofold: inhibition of the osteoblasts and deprivation of the osteoblasts of glucoprotein material due to a general anomaly of metabolism. This may perhaps explain the most serious forms of bone atrophy which are usually observable in cases of hyperfunction of the adrenal cortex. Senile osteoporosis should, in my opinion, be included in the first of our groups because it cannot be said to be brought about by any of the causes usually cited for osteoporosis– such as deficiency of sex hormones, excess of hormones from the adrenal cortex, deficiency of calcium, etc.–and in all probability it will depend on a progressive involution of the osteoblasts brought about by old age. Senile involution is an expression of the descending phase of life's parabola and it involves all the organs and all the parenchymatous tissues in the human body, but it does not cause a parallel reduction of functions and activities on all of them equally. The skeletal system is one of the first to feel these reductions, because in old age life necessarily becomes less intense. Consequently in the economy of the ageing subject the generally reduced level of metabolism brings about a sort of selection in the nourishment of the different organs and systems, and sometimes almost a dismantling of some of these in an attempt to fall in with the new and reduced level of activities of some of the parenchymatous tissues, activities which may be incomplete or even transferred elsewhere. We believe that the moment which originally determines the beginning of senile osteoporosis coincides with the involutional process of cellular metabolism that strikes at all parenchymatous tissue during old age–striking, in the case of osteoporosis, hardest of all at the bony tissues. There is, indeed, no doubt that certain essential processes of cellular metabolism do alter with age, and that the reduction in the activity of the gonads does have considerable importance. In any case, just as adolescence and old age cannot be explained only in terms of gonadal activity, so the involution of the skeleton cannot be due merely to the involution of the gonads. How should one then interpret the well known benefit afforded by administration of sex hormones in cases of osteoporosis? Probably the action of oestrogens and androgens is, in this case, of a pharmacological nature, and comparable, for instance, to the action of digitalis on the cardiac muscle. It will be remembered how digitalis acts almost exclusively on myofibrils which have become inadequate, and has little or no effect on a normal myocardium. Similarly, the sex hormones would seem to exert a stimulating action on osteoblasts that are on the way to involution, while they exert little or no action on normal osteoblasts. In support of this we have the findings of Urist and other workers, who demonstrated that the administration of sex hormones produces calcium and nitrogen retention only in osteoporotics, while in non-osteoporotic subjects of the same age it produces no effect. On the other hand, the action of the sex hormones might act in cases of senile osteoporosis by returning the changed level of protein metabolism to normal. From the data in the literature and from the results of our own investigations, I conclude that osteoporosis in general, and senile osteoporosis in particular, are first and foremost the result of a disturbance in the metabolism of bone, and that the metabolic disturbance is closely and exclusively related to the degree of activity and the state of activity of the cells in the bone. Lastly, I believe that senile osteoporosis should not be considered an actual disease but rather as one limited aspect of the normal descending parabola which affects to a greater or less degree all the tissues of the body

1. The syndrome of osteoporosis is reviewed and its various causes are mentioned. Osteoporosis in youngish patients without any demonstrable cause is referred to as "idiopathic." The scant literature on this condition is reviewed. Its clinical, radiological, biochemical and histological features are considered. 2. A series of thirty-eight cases is analysed, and illustrative case histories are described. The peculiarities of the disease as it is seen in women are discussed, particularly the relationship to pregnancy and lactation, which appear to act as precipitating factors, rather than being primarily causative. 3. The differential diagnosis is discussed. Osteogenesis imperfecta may not always be easy to distinguish; since it is really a "congenital osteoporosis" this is hardly surprising. 4. The following possible etiological factors are propounded (apart from pregnancy): nutritional, occupational, lack of sex hormone, liver dysfunction, loss of protein, diabetes, premature ageing, hypophosphatasia, "alarm reaction," and inheritance. None of them can be incriminated except in the odd case. The relationship between osteoporosis and idiopathic hypercalcuria is mentioned. The only conclusion regarding etiology is that some people are simply more prone to bone loss than are others, and in these a variety of accentuating factors may render the disorder clinically apparent. 5. The treatment of the condition is unsatisfactory, although occasionally a positive calcium balance may be obtained with sex hormones or intravenous infusion of plasma albumin or whole plasma. The general tendency seems to be towards clinical improvement (biologically "stabilisation" rather than improvement), but some patients become permanently crippled

Four cases of slipped upper femoral epiphyses in patients with intracranial tumours causing hypopituitarism and chiasmal compression are presented. Detailed endocrine studies in three cases showed severe deficiencies of growth hormone as well as of gonadotrophin and sex hormones. The literature is reviewed and the aetiology is discussed with special reference to Harris's hypothesis that an increase in growth hormone relative to oestrogen predisposes to slipping of the upper femoral epiphysis in humans, which these cases do not seem to support. In all cases the slip was bilateral, and it is emphasised that surgical treatment can provide only temporary fixation because fusion is dependent on correct hormonal therapy

1. Individuals who are normal and not osteoporotic seem to show retention of cortical bone at successive decades of life in proportion to the total lean body-mass. In patients with osteoporosis the weight of the skeleton decreases at a rate exceeding the physiological rate of atrophy of muscle, tendon and bone tissue that occurs with the time-dependent process of ageing. 2. Six patients representing the typical forms of osteoporosis commonly found in orthopaedic practice were investigated intensively over a period of three years and compared with individuals in whom there was no osteoporosis by studies of metabolic balance, Sr85 osteograms, and tetracycline deposition. 3. Studies of metabolic balance in patients with osteoporosis showed normal or negative calcium balances, but an equilibrium for the metabolism of nitrogen and phosphorus. Increased intake of calcium in the diet produced retention of calcium but not sufficient phosphorus, nitrogen or gain in weight to prove that the patient had made new bone and healed the osteoporosis. 4. Radio-isotope osteograms showed high, normal or low rates of change of uptake of Sr85 and the accretion rate was calculated to be normal or low in individuals with osteoporosis. High uptake of tetracycline by a small mass of bone tissue and by a relatively small percentage of the total number of osteons suggested that in an adult human being the calcium reserve in the skeleton is enormous. Thirty to 50 per cent of the total bone mass was sufficient to turn over 0·5 to 1·0 gramme, the amount of calcium utilised in twenty-four hours by the human adult. This was accomplished by structural or old bone throughout the entire skeleton, and by labile or newer bone located in approximately 10 per cent of the total number of Haversian cylinders or osteons. 5. Some of the unclosed or half-closed osteons were hyperactive in osteoporotic bones. In the process of remodelling of cortical bone a significant quantity of bone tissue was incompletely restored and there were, presumably as a result, intermittently large or small negative calcium balances. Osteoporosis may have been the cause, rather than the result, of the negative calcium balance. 6. The experimental and clinical literature of the past ten years, and studies on patients described in this critical review, were interpreted to indicate that prolonged calcium deficiency, castration, hyperadrenal corticoidism or a sedentary life may precipitate, accentuate and accelerate osteoporosis in individuals who are genetically predisposed to develop it. Sometimes high calcium intake or sex hormones, or both, may have slowed the rate of resorption but did not replace the deficit in cortical bone. 7. Further research is necessary to find the chief etiological factor and to produce the cure for this increasingly common disorder of the skeleton

The case histories of these Black Notley patients show that no serious harmful effects have been caused by pregnancies going to full term. Most of the patients had normal confinements; Caesarian sections were few and were usually done for obstetric reasons, not for fear of reactivation of the disease. This experience bears out a remark made to me by Marcel Galland. When asked if Caesarian sections were required for women who became pregnant after treatment at Berck for skeletal tuberculosis, he replied: "Jarnais! Tout passe!". Two patients in the series had artificial abortions, and one aborted spontaneously. Two of these three patients did not do as well as other patients whose pregnancies went to full term. Quite another question is whether the onset of skeletal tuberculosis sooii after pregnancy may be attributed to the pregnancy. In a group of women of child-bearing age, it would be difficult to distinguish between post hoc and propter hoc in considering this question. One patient of this series, H. Q. (Case 25), was admitted eight months pregnant with active tuberculosis of the knee; but pain in the joint had started fifteen months before admission, and the onset of disease no doubt preceded the pregnancy. Some of the patients admitted to Black Notley were mothers of young children hut there is no note of any pregnancy having preceded the onset of tuberculosis by a short interval. The follow-up reports of the married patients compare favourably with those of the unmarried. Further, it may be argued that pregnancy increases resistance to tuberculosis. Such a belief was current from the time of Hippocrates until the middle of the nineteenth century, and clinical evidence can be quoted in favour of such a view. In America, Lyman (1943) followed up 1,818 women who had been treated for tuberculosis in a sanatorium; many had married despite medical advice to the contrary. Lyman found that the late results of treatment were four times as good in the married patients as in the single women. Lyman says, "When we consider that the married group established this record in spite of the fact that 192 out of 315 gave histories of pregnancies (averaging 2·25 children each), it is clear that some factor not yet accounted for has exerted a profound influence in their cases.". I have speculated elsewhere as to what this factor may be (Wilkinson 1949). But it seems clear that increased sterol circulation in the body is associated with increased reticulo-endothelial activity (Fraser 1935). Thus reticulo-endothelial proliferation has been observed in the lesions of lupus following the administration of calciferol (Dowling, Gauvain and Macrae 1948). An increase of blood cholesterol is found during pregnancy. The sex hormones are sterols and might be expected to be raised in the marital state; it is perhaps significant that marital contacts form a group relatively immune to tuberculosis. There would appear to be good grounds for reassuring the married woman who has suffered from skeletal tuberculosis regarding the prospect of normal pregnancy. Many letters received from patients in a follow-up of this sort are poignant documents. There is no doubt that the majority of these women desire children as ardently as normal women, and that a safe confinement following skeletal tuberculosis is an excellent form of rehabilitation

Aims

The aim of this study was to explore risk factors for complications associated with dural tear (DT), including the types of DT, and the intra- and postoperative management of DT.

In patients with traumatic brain injury and fractures of long bones, it is often clinically observed that the rate of bone healing and extent of callus formation are increased. However, the evidence has been unconvincing and an association between such an injury and enhanced fracture healing remains unclear. We performed a retrospective cohort study of 74 young adult patients with a mean age of 24.2 years (16 to 40) who sustained a femoral shaft fracture (AO/OTA type 32A or 32B) with or without a brain injury. All the fractures were treated with closed intramedullary nailing. The main outcome measures included the time required for bridging callus formation (BCF) and the mean callus thickness (MCT) at the final follow-up. Comparative analyses were made between the 20 patients with a brain injury and the 54 without brain injury. Subgroup comparisons were performed among the patients with a brain injury in terms of the severity of head injury, the types of intracranial haemorrhage and gender. Patients with a brain injury had an earlier appearance of BCF (p < 0.001) and a greater final MCT value (p < 0.001) than those without. There were no significant differences with respect to the time required for BCF and final MCT values in terms of the severity of head injury (p = 0.521 and p = 0.153, respectively), the types of intracranial haemorrhage (p = 0.308 and p = 0.189, respectively) and gender (p = 0.383 and p = 0.662, respectively).

These results confirm that an injury to the brain may be associated with accelerated fracture healing and enhanced callus formation. However, the severity of the injury to the brain, the type of intracranial haemorrhage and gender were not statistically significant factors in predicting the rate of bone healing and extent of final callus formation.

We investigated the effect of progesterone on the nerve during lengthening of the limb in rats. The sciatic nerves of rats were elongated by leg lengthening for ten days at 3 mm per day. On alternate days between the day after the operation and nerve dissection, the progesterone-treated group received subcutaneous injections of 1 mg progesterone in sesame oil and the control group received oil only. On the fifth, tenth and 17th day, the sciatic nerves were excised at the midpoint of the femur and the mRNA expression level of myelin protein P0 was analysed by quantitative real time polymerase chain reaction. On day 52 nodal length was examined by electron microscopy, followed by an examination of the compound muscle action potential (C-MAP) amplitude and the motor conduction velocity (MCV) of the tibial nerve on days 17 and 52. The P0 (a major myelin glycoprotein) mRNA expression level in the progesterone-treated group increased by 46.6% and 38.7% on days five and ten, respectively. On day 52, the nodal length in the progesterone-treated group was smaller than that in the control group, and the MCV of the progesterone-treated group had been restored to normal.

Progesterone might accelerate the restoration of demyelination caused by nerve elongation by activating myelin synthesis.

The long-term effects of metal-on-metal arthroplasty are currently under scrutiny because of the potential biological effects of metal wear debris. This review summarises data describing the release, dissemination, uptake, biological activity, and potential toxicity of metal wear debris released from alloys currently used in modern orthopaedics. The introduction of risk assessment for the evaluation of metal alloys and their use in arthroplasty patients is discussed and this should include potential harmful effects on immunity, reproduction, the kidney, developmental toxicity, the nervous system and carcinogenesis.