Objectives. This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone. Methods. A total of 30 rats were divided equally into normal, ovariectomized, and partially nephrectomized groups. Cortical and trabecular bone segments from each animal underwent micro-CT to assess their average and minimum axial rigidities using structural rigidity analysis. Following imaging, all specimens were subjected to uniaxial compression and assessment of mechanically-derived axial rigidity. Results. The average structural rigidity-based axial rigidity was well correlated with the average mechanically-derived axial rigidity results (R. 2. = 0.74). This correlation improved significantly (p < 0.0001) when the CT-based Structural Rigidity Analysis (CTRA) minimum axial rigidity was correlated to the mechanically-derived minimum axial rigidity results (R. 2. = 0.84). Tests of slopes in the mixed model regression analysis indicated a significantly steeper slope for the average axial rigidity compared with the minimum axial rigidity (p = 0.028) and a significant difference in the intercepts (p = 0.022). The CTRA average and minimum axial rigidities were correlated with the mechanically-derived average and minimum axial rigidities using paired t-test analysis (p = 0.37 and p = 0.18, respectively). Conclusions. In summary, the results of this study suggest that structural rigidity analysis of micro-CT data can be used to accurately and quantitatively measure the axial rigidity of bones with metabolic pathologies in an experimental rat model. It appears that minimum axial rigidity is a better model for measuring bone rigidity than average axial rigidity

1. The use of acrylic cement in bonding femoral head prostheses to bone is described. 2. No sign of deterioration of the bond between the cement and bone has been seen in histological preparations up to three and a quarter years after operation, and no harmful effects have been recognised, or suspected, in 455 patients in whom it has been used. 3. The technique is considered justifiable in elderly patients where the medullary canal is large and the cortex of the femur is thin and brittle

Limited success in regenerating large bone defects has been achieved by bridging them with osteoconductive materials. These substitutes lack the osteogenic and osteoinductive properties of bone autograft. A direct approach would be to stimulate osteogenesis in these biomaterials by the addition of fresh bone-marrow cells (BMC). We therefore created osteoperiosteal gaps 2 cm wide in the ulna of adult rabbits and either bridged them with coral alone (CC), coral supplemented with BMC, or left them empty. Coral was chosen as a scaffold because of its good biocompatibility and resorbability. In osteoperiosteal gaps bridged with coral only, the coral was invaded chiefly by fibrous tissue. It was insufficient to produce union after two months. In defects filled with coral and BMC an increase in osteogenesis was observed and the bone surface area was significantly higher compared with defects filled with coral alone. Bony union occurred in six out of six defects filled with coral and BMC after two months. An increase in the resorption of coral was also observed, suggesting that resorbing cells or their progenitors were present in bone marrow and survived the grafting procedure. Our findings have shown that supplementation of coral with BMC increased both the resorption of material and osteogenesis in defects of a clinical significance

Secondary sterilisation of allograft bone by gamma irradiation is common, but the conditions under which it is performed vary between tissue banks. Some do so at room temperature, others while the bone is frozen. Bone is made brittle by irradiation because of the destruction of collagen alpha chains, probably mediated by free radicals generated from water molecules. Freezing reduces the mobility of water molecules and may therefore decrease the production of free radicals. We found that bone irradiated at −78°C was less brittle and had less collagen damage than when irradiated at room temperature. These findings may have implications for bone-banking

1. Clinical, radiological and pathological findings in seven cases of rheumatoid arthritis with giant bone cysts are presented. 2. In three cases the large cysts represented massive involvement of subchondral bone by rheumatoid granulation tissue; in two cases the cysts were due to rheumatoid nodules, and in two other cases the diagnosis was made only on the radiological findings. 3. The pathogenesis of this condition is discussed. It is suggested that cystic bone lesions in rheumatoid arthritis can arise either by replacement of subchondral bone by the rheumatoid process, or by the formation of rheumatoid nodules within the bone

We analysed the outcome of patients with primary non-metastatic diaphyseal sarcomas who had en bloc resection with preservation of the adjoining joints and reconstruction with re-implantation of sterilised tumour bone after extracorporeal radiation (50 Gy). Between March 2005 and September 2009, 32 patients (16 Ewing’s sarcoma and 16 osteogenic sarcoma) with a mean age of 15 years (2 to 35) underwent this procedure. The femur was the most common site in 17 patients, followed by the tibia in 11, humerus in three and ulna in one. The mean resected length of bone was 19 cm (10 to 26). A total of 31 patients were available at a mean follow-up of 34 months (12 to 74). The mean time to union for all osteotomy sites was 7.3 months (3 to 28): metaphyseal osteotomy sites united quicker than diaphyseal osteotomy sites (5.8 months (3 to 10) versus 9.5 months (4 to 28)). There were three local recurrences, all in soft-tissue away from irradiated graft. At the time of final follow-up, 19 patients were free of disease, one was alive with disease and 11 had died of disease. The mean Musculoskeletal Tumor Society Score for 29 patients evaluated at the last follow-up was 26 (9 to 30). Extracorporeal irradiation is an oncologically safe and inexpensive technique for limb salvage in diaphyseal sarcomas and has good functional results

We evaluated the clinical results and complications after extra-articular resection of the distal femur and/or proximal tibia and reconstruction with a tumour endoprosthesis (MUTARS) in 59 patients (mean age 33 years (11 to 74)) with malignant bone or soft-tissue tumours. According to a Kaplan–Meier analysis, limb survival was 76% (95% confidence interval (CI) 64.1 to 88.5) after a mean follow-up of 4.7 years (one month to 17 years). Peri-prosthetic infection was the most common indication for subsequent amputation (eight patients). Survival of the prosthesis without revision was 48% (95% CI 34.8 to 62.0) at two years and 25% (95% CI 11.1 to 39.9) at five years post-operatively. Failure of the prosthesis was due to deep infection in 22 patients (37%), aseptic loosening in ten patients (17%), and peri-prosthetic fracture in six patients (10%). Wear of the bearings made a minor revision necessary in 12 patients (20%). The mean Musculoskeletal Tumor Society score was 23 (10 to 29). An extensor lag > 10° was noted in ten patients (17%). These results suggest that limb salvage after extra-articular resection with a tumour prosthesis can achieve good functional results in most patients, although the rates of complications and subsequent amputation are higher than in patients treated with intra-articular resection. Cite this article: Bone Joint J 2013;95-B:1425–31

1 . Six patients have been presented in whom an established diagnosis of non-osteogenic fibroma of bone was made. Metaplastic bone was identified within the tumour tissues. 2. Three other patients are reported in whom the diagnosis appeared to be, on radiological and histological grounds, either fibrous dysplasia or non-osteogenic fibroma. 3. This evidence has convinced the author that the two lesions are frequently not distinctive and that they are, in fact, closely related. Because the natural history of the two conditions, especially in their simple or monostotic form, is also the same, there is good reason to consider them as varying histological manifestations of the same pathogenetic process

We used a rat model in vivo to study the effects of particulate bone cements at the bone-implant interface. A ceramic pin was implanted into the tibiae of 48 rats. Three types of particle of clinically relevant size were produced from one bone-cement base without radio-opacifier, with zirconium dioxide (ZrO. 2. ) and with barium sulphate (BaSO. 4. ). The rats were randomly assigned to four groups to receive one of the three bone cements or normal saline with 2% v/v Sprague-Dawley serum as the control. A total of 10. 9. particles was injected into the knee at 8, 10 and 12 weeks after the original surgery. The animals were killed at 14 weeks and the tibiae processed for histomorphometry. The area of fibrous tissue and the gap between the implant and bone were measured using image analysis. All three types of particle were associated with a larger area of bone resorption than the control. Only in the case of the BaSO. 4. -containing cement did this reach statistical significance (p = 0.01). Particles of bone cement appear to promote osteolysis at the bone-implant interface and this effect is most marked when BaSO. 4. is used as the radiopaque agent

We retrospectively reviewed 71 histopathologically-confirmed bone and soft-tissue metastases of unknown origin at presentation. In order to identify the site of the primary tumour all 71 cases were examined with conventional procedures, including CT, serum tumour markers, a plain radiograph, ultrasound examination and endoscopic examinations, and 24 of the 71 cases underwent 2-deoxy-2-[F-18] fluoro-D-glucose positron emission tomography (FDG-PET). This detected multiple bone metastases in nine patients and the primary site in 12 of the 24 cases; conventional studies revealed 16 primary tumours. There was no significant difference in sensitivity between FDG-PET and conventional studies. The mean maximal standardised uptake value of the metastatic tumours was significantly higher than that of the primary tumours, which is likely to explain why FDG-PET did not provide better results. It was not superior to conventional procedures in the search for the primary site of bone and soft-tissue metastases; however, it seemed to be useful in the staging of malignancy

1. In the treatment of chronic osteomyelitis the most troublesome factor is the infected bone cavity. This is seldom obliterated spontaneously by bone regeneration. The number of procedures designed to fill the cavity, since the beginning of the century, show how much it troubles the surgeon. 2. The use of bone grafts in the treatment of chronic osteomyelitis has been studied. One hundred and twenty cases are reviewed (the largest series in the literature), the follow-up being between two and ten years. The most common lesion was a bone cavity, with or without a sequestrum. 3. Treatment must include the removal of infected soft tissues as well as sclerosed bone, and must be done under appropriate antibiotic control. The value of cancellous bone grafts in filling infected cavities in the metaphysio-epiphysial regions is especially emphasised. 4. The results were gratifying, only four relapses occurring in 120 cases

1. Histochemical studies have been made of the distribution of alkaline phosphatase, glycogen and acid mucopolysaccharides in normal growing bones (mice, rats and men) and also in forty cases of pathological bone processes (neoplastic and dystrophic). 2. The study of normal material confirmed that alkaline phosphatase is plentiful in calcification of cartilage and even more plentiful in bone formation (whether enchondral or direct). 3. It was observed that glycogen increased in the cartilage areas about to be calcified, and that it disappeared in those calcified. It seemed that osteoblasts did not always contain glycogen. 4. In the pathological material (tumours and dystrophic processes) there was great phosphatase activity in the osteogenic areas and also in the cartilage about to be calcified. Whereas glycogen was plentiful in some cases of neoplastic or reactive osteogenesis, it was absent from others. 5. In every area of normal or pathological ossification, the presence of phosphatase seems to be a rule; glycogen is often but not always present. 6. It appears that alkaline phosphatase plays an important role in the formation of the protein matrix of bone, but is not associated with the elaboration of the mucoprotein cartilage matrix. We believe it is premature to draw any definite conclusion on the behaviour and role of the metachromatic substances in the processes of calcification and ossification. The histochemical study of alkaline phosphatase has shown that this is a valuable method in the detection of reactionary or pathological osteogenic processes which in some cases are difficult to demonstrate with the usual histological methods

The aim of limb-salvage surgery in malignant bone tumours in children is to restore function and eradicate local disease with as little morbidity as possible. Allografts are associated with a high rate of complications, particularly malunion at the allograft-host junction. We describe a simple technique which enhances union of allograft to host bone taking advantage of the discrepancy in size between the adult allograft and the child’s bone. This involves lifting a flap of periosteum before resection from the host bone, which is then telescoped into the allograft medullary canal, which may require internal burring or splitting, for a distance of 1.5 to 2 cm and covering the bone junction with the periosteal flap. This is more stable than conventional end-to-end opposition. For each centimetre of telescoping the surface area available for bony union is increased more than three times. The periosteal flap also augments union. Additional surface fixation with a plate and screws is not necessary. We have used this technique in nine children, in eight of whom there was complete union at a mean of 16 weeks. Delayed union, associated with generalised limb osteoporosis, occurred in one. Early mobilisation, with weight-bearing by three weeks, was possible. There was only one fracture of the allograft

We report the use of porous metal acetabular revision shells in the treatment of contained bone loss. The outcomes of 53 patients with ≤ 50% acetabular bleeding host bone contact were compared with a control group of 49 patients with > 50% to 85% bleeding host bone contact. All patients were treated with the same type of trabecular metal acetabular revision shell. The mean age at revision was 62.4 years (42 to 80) and the mean follow-up of both groups was 72.4 months (60 to 102). Clinical, radiological and functional outcomes were assessed. There were four (7.5%) mechanical failures in the ≤ 50% host bone contact group and no failures in the > 50% host bone contact group (p = 0.068). Out of both groups combined there were four infections (3.9%) and five recurrent dislocations (4.9%) with a stable acetabular component construct that were revised to a constrained liner. Given the complexity of the reconstructive challenge, porous metal revision acetabular shells show acceptable failure rates at five to ten years’ follow-up in the setting of significant contained bone defects. This favourable outcome might be due to the improved initial stability achieved by a high coefficient of friction between the acetabular implant and the host bone, and the high porosity, which affords good bone ingrowth

We implanted bone harvest chambers (BHCs) bilaterally in ten mature male New Zealand white rabbits. Polyethylene particles (0.3 ± 0.1 −m in diameter, 6.4×10. 12. particles/ml) were implanted for two, four or six weeks bilaterally in the BHCs, with subsequent removal of the ingrown tissue after each treatment. In addition to the particles, one side also received 1.5 −g of recombinant transforming growth factor ß1 (TGFβ1). At two weeks, the bone area as a percentage of total area was less in chambers containing TGFβ compared with those with particles alone (7.8 ± 1.3% v 16.9 ± 2.7% respectively; 95% confidence interval (CI) for difference -14.0 to -4.30; p = 0.002). At four weeks, the percentage area of bone was greater in chambers containing TGFβ compared with those with particles alone (31.2 ± 3.4% v 22.5 ± 2.0% respectively; 95% CI for difference 1.0 to 16.4; p = 0.03). There were no statistical differences at six weeks, despite a higher mean value with TGFβ treatment (38.2 ± 3.9% v 28.8 ± 3.5%; 95% CI for difference -4.6 to 23.3; p = 0.16). The number of vitronectin-receptor-positive cells (osteoclast-like cells) was greater in the treatment group with TGFβ compared with that with particles alone; most of these positive cells were located in the interstitium, rather than adjacent to bone. TGFβ1 is a pleotropic growth factor which can modulate cellular events in the musculoskeletal system in a time- and concentration-dependent manner. Our data suggest that there is an early window at between two and six weeks, in which TGFβ may favourably affect bone ingrowth in the BHC model. Exogenous growth factors such as TGFβ may be a useful adjunct in obtaining osseointegration and bone ingrowth, especially in revisions when there is compromised bone stock and residual particulate debris

1. A study is reported of 190 femora in 174 patients in whom self-curing acrylic cement had been present in the medullary cavity of the upper end of the femur for the fixation of an endoprosthesis for an average period of four years. 2. The bone remained radiologically normal in 81 per cent of cases. 3. Improvement in the thickness of the cortex from pre-existing atrophy was noted in 2·6 per cent. 4. In 4·7 per cent the bone showed some atrophy after insertion of the cement. This exceeded 10 per cent in only two cases. All were originally osteoporotic from polyarthritis; all were satisfactory as regards the arthroplasty itself, and the atrophy could usually be explained by disuse resulting from the state of the opposite lower extremity, or the knee on the same side. 5. In 9·4 per cent there was fusiform hypertrophy of the femoral cortex, the bony texture remaining normal. This appearance was considered physiological and benign. 6. In 2·2 per cent there were changes for which the most likely explanation is chronic non-suppurative osteitis, though no collateral evidence of infection was found. 7. In 44·8 per cent there was a thin line of condensation in the cancellous bone demarcating the outer limits of the cement. This is considered to be physiological and not to indicate failure of immobilisation. 8. In 37·2 per cent there was slight resorption of the cut surface of the calcar femorale. This is considered to be physiological and to confirm the efficacy of weight transmission by cement lower down in the medullary cavity

1. Forty patients with solitary eosinophilic granuloma of bone from the Hospital for Sick Children, Toronto, have been reviewed. They had clinical and laboratory findings similar to those reported by others except for the erythrocyte sedimentation rate, which was raised in nearly half the patients tested. 2. Radiographs in all cases showed the lesion to be osteolytic. In the skull and cervical spine there was no bony reaction ; in the thoracic and lumbar spine the typical picture of Calvés disease was produced; in long bones the cortex commonly showed endosteal erosion and periosteal reaction. 3. In one patient the lesion progressed so rapidly that the body of a cervical vertebra was destroyed within ten days. 4. The differential diagnosis includes sarcoma. Biopsy is essential. 5. All the patients improved regardless of the treatment they received. Complications were due either to the site of the lesion or to its treatment. 6. Expansion of the lesion after biopsy indicates a more widespread manifestation of histiocytosis X

1. Paralysis caused by anterior nerve root section, or by peripheral nerve section, leads to marked changes in the bones and muscles of the affected limb in experimental animals. Vascular changes are not the cause of the bone atrophy in a paralysed limb. 2. The altered properties of the bones of a paralysed limb are due almost entirely to a loss in the quantity of bone; bone quality is only slightly altered. 3. The bone changes that follow paralysis are due to the secondary loss of muscular activity. No evidence could be obtained that nerves exert any specific, trophic influence on bone

Old calcified fibrin coagula are frequently found in simple bone cysts. They provide a scaffold on which new bone is laid down, in a process analogous to endochondral ossification. It is suggested that these coagula are derived in substantial part from the plasma-like contents of the cyst, after the release of plasma-clotting factors as the result of injury. Major haemorrhage is not involved and in many cases there is no antecedent fracture. The phenomenon is not seen in other common cystic conditions of bone and its recognition is thus helpful in the histological diagnosis of simple bone cyst. Cystic bone infarcts and their possible confusion with simple bone cysts are also briefly discussed

The fatigue failure of bone cement, leading to loosening of the stem, is likely to be one mode of failure of cemented total hip replacements. There is strong evidence that cracks in the cement are initiated at voids which act as stress risers, particularly at the cement-stem interface. The preferential formation of voids at this site results from shrinkage during polymerisation and the initiation of this process at the warmer cement-bone interface, which causes bone cement to shrink away from the stem. A reversal of the direction of polymerisation would shrink the cement on to the stem and reduce or eliminate the formation of voids at this interface. We have investigated this by implanting hip prostheses, at room temperature or preheated to 44°C, into human cadaver femora kept at 37°C. Two types of bone cement were either hand-mixed or vacuum-mixed before implantation. We found that the area of porosity at the cement-stem interface was dramatically reduced by preheating the stem and that the preheating temperature of 44°C determined by computer analysis of transient heat transfer was the minimum required to induce initial polymerisation at the cement-stem interface. Temperature measurements taken during these experiments in vitro showed that preheating of the stem caused a negligible increase in the temperature of the bone. Reduction of porosity at the cement-stem interface could significantly increase the life of hip arthroplasties