Abundant implant-derived biomaterial wear particles are generated in aseptic loosening and are deposited in periprosthetic tissues in which they are phagocytosed by mononuclear and multinucleated macrophage-like cells. It has been stated that the multinucleated cells which contain wear particles are not bone-resorbing osteoclasts. To investigate the validity of this claim we isolated human osteoclasts from giant-cell tumours of bone and rat osteoclasts from long bones. These were cultured on glass coverslips and on cortical bone slices in the presence of particles of latex, PMMA and titanium. Osteoclast phagocytosis of these particle types was shown by light microscopy, energy-dispersive X-ray analysis and SEM. Giant cells containing phagocytosed particles were seen to be associated with the formation of resorption lacunae. Osteoclasts containing particles were also calcitonin-receptor-positive and showed an inhibitory response to calcitonin. Our findings demonstrate that osteoclasts are capable of phagocytosing particles of a wide range of size, including particles of polymeric and metallic bio-materials found in periprosthetic tissues, and that after particle phagocytosis, they remain fully functional, hormone-responsive, bone-resorbing cells

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Muller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material

The August 2024 Oncology Roundup³⁶⁰ looks at: What factors are associated with osteoarthritis after cementation for benign aggressive bone tumour of the knee joint: a systematic review and meta-analysis; Recycled bone grafts treated with extracorporeal irradiation or liquid nitrogen freezing after malignant tumour resection; Intercalary resection of the tibia for primary bone tumours: are vascularized fibula autografts with or without allografts a durable reconstruction?; 3D-printed modular prostheses for the reconstruction of intercalary bone defects after joint-sparing limb salvage surgery for femoral diaphyseal tumours; Factors influencing the outcome of patients with primary Ewing’s sarcoma of the sacrum; The significance of surveillance imaging in children with Ewing’s sarcoma and osteosarcoma; Resection margin and soft-tissue sarcomas of the extremities treated with limb-sparing surgery and postoperative radiotherapy.

1. A general picture of the histological state of the bone-cement junction, up to seven years after implantation, is presented as a result of the study of twenty-three human specimens. 2. The transmission of load from cement to bone occurs at isolated points through the medium of newly formed fibrocartilage. 3. It is clear that this fibrocartilage has been produced in response to mechanical pressure on fibrous tissue which has undergone compression between cement and underlying bone. 4. Direct contact exists between the surface of the cement and the newly formed fibrocartilage at these sites of load transmission. 5. Load-bearing fibrocartilage frequently shows areas of ossification extending into it from the underlying bone. 6. Where soft tissues in contact with cement are too thick or too delicate for load transmission a thin layer of giant-cell cytoplasm coats the cement surface. 7. No collections of giant cells to form granulomatous or caseating areas have been seen. 8. Fat storage, indicating the absence of chemical irritation, can occur within ten microns of the cement surface

1. Penetrating defects were cut in the femora of twenty-five albino rats. In fifteen of the animals the defects in the right legs were protected with cellulose-acetate shields while those in the left legs were unprotected and allowed to heal as controls. In the remaining ten animals the defects in both legs were protected with shields made of homogenous organic bone. 2. New bone was found to proliferate into the concavity of the shields in most of the animals and this protruded beyond the contour of the femur. The development of the protuberance appeared to depend upon the degree to which the shield was adapted to the femoral surface. 3. The cellulose-acetate shield was not removed by the host, but the homogenous organic bone was actively resorbed; multinucleated giant cells were associated with this process. 4. There are indications that the maintenance of the protuberance is dependent upon the continued presence of the shield. Exostoses protected by intact cellulose-acetate shields have been recognised up to eighteen months after operation. 5. The function of the shield in the formation of the bony protuberance is thought to be two-fold, in that it protects the haematoma from invasion by non-osteogenic extra-skeletal connective tissue, and that it governs the size of the haematoma and prevents its distortion by the pressure of the overlying soft tissue

Aims

Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context.

Aims

To evaluate mid-to long-term patient-reported outcome measures (PROMs) of endoprosthetic reconstruction after resection of malignant tumours arising around the knee, and to investigate the risk factors for unfavourable PROMs.

1. Experience with a refined type of implantable electrode for the myo-electric control of externally powered prostheses is reported. 2. The electrodes are externally energised by electromagnetic induction and therefore do not contain any battery cells. The myo-potentials are transmitted in frequency-modulated form and detected by a receiver placed on the skin. The implantable electrode, measuring 5x11x4 millimetres, is encapsulated in epoxy resin. 3. Six electrodes have been implanted in the forearms of two normal subjects and two below-elbow amputees. The time of implantation ranged from three to fifteen months. Macroscopically, a fibrous capsule developed around the electrodes. Histological examination showed a capsule of granulation tissue of varying thickness with slight inflammatory reaction and foreign-body giant cells. 4. In all cases except one the signals received have been of high quality as ascertained by conventional electromyography and frequency analysis. There has been no significant deterioration in signal quality during the follow-up periods. 5. The major source of failure was fatigue fracture of the gold wires making contact with the body tissues. In one case, however, the electrode was still functioning normally at the time of removal fifteen months after insertion. 6. The patients have not been inconvenienced either by the operative procedures or by the presence of the electrodes in the tissues

Aims

The aim of this study was to investigate the incidence and characteristics of instrumentation failure (IF) after total en bloc spondylectomy (TES), and to analyze risk factors for IF.

We analysed revised Mathys isoelastic polyacetal femoral stems with stainless-steel heads and polyethylene acetabular cups from eight patients in order to differentiate various types of particle of wear debris. Loosening of isoelastic femoral stems is associated with the formation of polyacetal wear particles as well as those of polyethylene and metal. All three types of particle were isolated simultaneously by tissue digestion followed by sucrose gradient centrifugation. Polyacetal particles were either elongated, ranging from 10 to 150 μm in size, or shred-like and up to 100 μm in size. Polyethylene particles were elongated or granules, and were typically submicron or micronsized. Polyacetal and polyethylene polymer particles were differentiated by the presence of BaSO. 4. , which is added as a radiopaque agent to polyacetal but not to polyethylene. This was easily detectable by back-scattered SEM analysis and verified by energy dispersive x-ray analysis. Two types of foreign-body giant cell (FBGC) were recognised in the histological specimens. Extremely large FBGCs with irregular polygonal particles showing an uneven, spotty birefringence in polarised light were ascribed to polyacetal debris. Smaller FBGCs with slender elongated particles shining uniformly brightly in polarisation were related to polyethylene. Mononucleated histiocytes containing both types of particle were also present. Our findings offer a better understanding of the processes involved in the loosening of polyacetal stems and indicate why the idea of ‘isoelasticity’ proved to be unsuccessful in clinical practice

1 . Implants of heterogenous cartilage are known to excite a foreign body reaction in host tissues. In these experiments the way such implants hinder the spread of ossification across a fracture gap was studied. A segment of bone and periosteum was excised from both fibulae in twelve young grivet monkeys, and epiphysial cartilage from a four-day- old rat was implanted in the gap on the left side. The repair processes were investigated at intervals up to twenty-eight weeks. 2. On both sides the gaps were filled by fibrous tissue growing in from the adjacent muscle, and four weeks elapsed before callus started to form. Thereafter ossification across the gap was active on the right side, with bony union in seven or eight weeks. 3. On the left side the implant was slowly resorbed by macrophages and giant cells. Ossification made little headway in the gap after the seventh week. Remains of the implant were found up to the end of the period covered by the experiment. The ends of the fragments were united by fibrous tissue. 4. The fifth to the eighth week seemed to be a critical period, during which the implant and its surrounding inflammatory cells hindered chondrification and ossification and prevented fusion of the masses of callus at the ends of the fragments. 5. It is concluded that anything that impedes callus formation across the fracture line during this critical period may lead to non-union

Aims

Long non-coding RNAs (lncRNAs) act as crucial regulators in osteoporosis (OP). Nonetheless, the effects and potential molecular mechanism of lncRNA PCBP1 Antisense RNA 1 (PCBP1-AS1) on OP remain largely unclear. The aim of this study was to explore the role of lncRNA PCBP1-AS1 in the pathogenesis of OP.

Bone regeneration and repair are crucial to ambulation and quality of life. Factors such as poor general health, serious medical comorbidities, chronic inflammation, and ageing can lead to delayed healing and nonunion of fractures, and persistent bone defects. Bioengineering strategies to heal bone often involve grafting of autologous bone marrow aspirate concentrate (BMAC) or mesenchymal stem cells (MSCs) with biocompatible scaffolds. While BMAC shows promise, variability in its efficacy exists due to discrepancies in MSC concentration and robustness, and immune cell composition. Understanding the mechanisms by which macrophages and lymphocytes – the main cellular components in BMAC – interact with MSCs could suggest novel strategies to enhance bone healing. Macrophages are polarized into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, and influence cell metabolism and tissue regeneration via the secretion of cytokines and other factors. T cells, especially helper T1 (Th1) and Th17, promote inflammation and osteoclastogenesis, whereas Th2 and regulatory T (Treg) cells have anti-inflammatory pro-reconstructive effects, thereby supporting osteogenesis. Crosstalk among macrophages, T cells, and MSCs affects the bone microenvironment and regulates the local immune response. Manipulating the proportion and interactions of these cells presents an opportunity to alter the local regenerative capacity of bone, which potentially could enhance clinical outcomes.

Cite this article: Bone Joint Res 2024;13(9):462–473.

Out of 21 900 cases filed at the Latin-American Registry of Bone Pathology between April 1940 and July 1981, there were 987 with Paget's disease (4.51 per cent); 62 of these (6.28 per cent) were complicated by sarcoma and two were associated with giant-cell tumours of bone (osteoclastoma) without signs of malignancy. There was a slight predominance of men and the ages ranged from 45 to 87 years, with an average of 66 years. The most frequent sites were the femur (23 cases), the humerus (nine), the pelvis (10), and the tibia (nine). The low incidence of vertebral involvement (five cases) is noteworthy and is in sharp contrast to uncomplicated Paget's disease. The most common tumour type was osteosarcoma (39 cases), followed by fibrosarcoma (15 cases); other varieties (chondrosarcoma, malignant fibrous histiocytoma and reticulum-cell sarcoma) were much rarer. Most of the sarcomata occurred when the Paget's disease was polyostotic. Tumours often developed simultaneously, or at short time intervals, in the same or different bones; these bones had, in all cases, been affected by Paget's disease. The histological features of the osteosarcomata were characteristic, with large numbers of osteoclast giant cells, alternating with atypical osteoblasts, thus exaggerating the anarchic remodelling process of Paget's disease. The neighbouring areas of the pagetic bone showed an increased number of osteoclasts. These facts suggest a possible pathogenetic relationship between sarcoma and Paget's disease; the possibility of both processes having a viral aetiology is discussed

1. One hundred and seventy-nine cases of primary malignant bone tumour and giant-cell tumour seen at the Middlesex Hospital since 1925 are reviewed. Tumours arising from non-skeletal tissues in bone have been excluded. 2. The following histological classification is used. Osteosarcoma (osteoblast sarcoma): This tumour is not synonymous with osteogenic (bone-forming) sarcoma. The essential feature is the formation of osteoid tissue by malignant osteoblasts, with no intermediate matrix of cartilage or fibrous tissue. It is the most malignant bone tumour and only four of the thirty-two patients survived three years. Chondrosarcoma: These tumours are composed of cartilage, and some show secondary ossification. The behaviour of this group is related to the degree of cartilaginous differentiation. In general, compared with the osteosarcoma, it is of low-grade malignancy. More than half of the sixty-eight patients survived four years. Fibrosarcoma: The essential feature of this tumour is the production of collagen by malignant fibroblastic tumour cells. Tumours of this type invading the medullary cavity have an average prognosis between that of an osteosarcoma and a chondrosarcoma. Nine of the thirty-four patients survived three years. Spindle-cell sarcoma: These tumours are composed of spindle cells which produce no diagnostic matrix. In spite of the lack of differentiation the outlook is not hopeless. Six of the eleven patients survived for five years or more. Giant-cell tumour: This tumour is composed of a cellular stroma with diagnostic giant cells resembling osteoclasts. It is by no means a benign lesion, for half the tumours recurred after treatment and a quarter of the patients died with metastases. 3. The subdivision of primary malignant skeletal tumours into groups according to the histological pattern appears to be reflected in the behaviour of the individual tumours after treatment. The prognosis of each group has been stated in the appropriate sections

Aims

The aim of this study was to investigate the feasibility of application of a 3D-printed megaprosthesis with hemiarthroplasty design for defects of the distal humerus or proximal ulna following tumour resection.

Aims

Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip centre of rotation (COR) on postoperative dislocation using a CT-based 3D model, as well as other potential risk factors for dislocation.

Aims

The aims of this study were to determine the diagnostic yield of image-guided biopsy in providing a final diagnosis in patients with suspected infectious spondylodiscitis, to report the diagnostic accuracy of various microbiological tests and histological examinations in these patients, and to report the epidemiology of infectious spondylodiscitis from a country where tuberculosis (TB) is endemic, including the incidence of drug-resistant TB.