Aims

Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology.

We obtained samples of spinal accessory nerve from patients undergoing radical surgery for tumours or nerve grafting in the neck. These were analysed by light and electron microscopy for the type of fibre. All contained fibres consistent with non-proprioceptive sensory function including pain

We present the case of a 63-year-old woman who sustained an acrylic cement burn of the sciatic nerve at hip replacement. She was treated by resection of the damaged segment and grafting. Electron microscopy showed that the nerve was nearly normal 1 cm from the cement margin indicating that this is a safe level for resection

1. The orientation of collagen fibres of the menisci of the knee has been demonstrated by polarised light microscopy. 2. As might be supposed from its fibre structure, the ultimate tensile strength of the meniscal tissue is dependent upon the axis of loading. 3. The tensile strength of the meniscus is similar to that of articular cartilage

Aims

For cementless implants, stability is initially attained by an interference fit into the bone and osteo-integration may be encouraged by coating the implant with bioactive substances. Blood based autologous glue provides an easy, cost-effective way of obtaining high concentrations of growth factors for tissue healing and regeneration with the intention of spraying it onto the implant surface during surgery. The aim of this study was to incorporate nucleated cells from autologous bone marrow (BM) aspirate into gels made from the patient’s own blood, and to investigate the effects of incorporating three different concentrations of platelet rich plasma (PRP) on the proliferation and viability of the cells in the gel.

We studied factors contributing to the initiation of fracture and failure of a zirconia ceramic femoral head. The materials retrieved during a revision total hip replacement were submitted to either visual, stereomicroscopic and scanning electron microscopy (SEM) or SEM and energy-dispersive x-ray analysis. X-ray diffraction was performed in order to investigate the extent of tetragonal to monoclinic phase transition. Histological examination was performed on the periprosthetic tissues. The results showed that failure was due to the propagation during clinical use of defects which may have been introduced into the material during the processing of the ceramic, rather than those intrinsic to zirconia. The literature relating to previous failures of zirconia components is reviewed

Teratomas in the spinal cord are rare. We report a case in a 54-year-old man. CT scans revealed tumours of different densities within the spinal canal; this heterogeneity may help to differentiate teratoma from other spinal cord tumours. After resection of the tumours under microscopy, the result was excellent. Histological examination showed a variety of tissues, including elements of all three germinal layers

An extremely strong mechanical bond between cement and bone was observed in three patients with cemented hip protheses who underwent revision operations. The nature of the bone--cement attachment was studied by electron microscopy. The tissue at the interface was found to be made up of viable bone alternating with areas of soft tissue containing macrophages. The important qualitative differences between this reaction and the reaction seen around inert materials such as titanium are discussed

Results are given of a study of four cases of osteogenesis imperfecta using biophysical methods comprising microradiography, microscopy using polarised light, and x-ray diffraction. Rebuilding of bone tissue was infrequent in the material studied and has been shown to occur in an abnormal manner. The mineralisation of the bone is more uniform than is found in normal bone. The collagen has an abnormal organisation and is sparse. The ultrastructure of bone salts and their orientation are as in normal bone

1. A method is described for the in vivo and in vitro study of osteogenesis by implanting a modified transparent chamber in half lop-eared rabbits (as originated by Sandison 1928). This method allows the daily observation and photography of the developing bone and the study of its intimate connection with the vascularity of the area. 2. The osteogenetic potential of a variety of substances can also be investigated by this method. The tissue in the chamber can easily be prepared for its final examination by optical and electron microscopy and by other laboratory techniques

Specimens of tissue from haemophilic synovium and articular cartilage were collected from 39 patients during reconstructive surgery. They were studied by histochemistry, electron microscopy and microprobe analysis. The detailed findings are presented and discussed. It is suggested that haemophilic arthropathy is the result of a number of mechanisms affecting the synovial lining which becomes progressively fibrotic and the hyaline cartilage which disintegrates and is eventually lost. Mechanical and chemical processes cause degeneration of cells but enzymatic processes appear to be primarily responsible for the degradation of the matrix of the articular cartilage

We obtained specimens of growth-plate cartilage from four patients with osteogenesis imperfecta. Light microscopy showed structural changes in the tissue and morphological changes in chondrocytes and matrix, particularly in the hypertrophic zone. There were changes in the process of calcification in the primary mineralisation zone of the cartilage. We also found histochemical changes in the matrix glycosaminoglycans (GAGs) in the zones where physiological mineralisation was disturbed and where the trabeculae were interrupted and poorly mineralised. In addition to the known molecular defects in collagen, changes in GAGs and non-collagenous proteins are important factors in the pathogenesis of the disease

Three madreporic prostheses in two patients were examined to evaluate resorption and formation of the surrounding bone tissue. All three prostheses were firmly fixed and had no clinical or radiographic signs of loosening. Transverse sections were examined by scanning electron microscopy at 40 days, 11 months and 2.5 years after implantation. The findings suggest that adaptive bone remodelling varies along the length of the stem; that bone resorption and formation are related to the time after implant; and that new bone formation (woven bone) can be found very close to the madreporic surface

Objectives

Bone tissue engineering is one of the fastest growing branches in modern bioscience. New methods are being developed to achieve higher grades of mineral deposition by osteogenically inducted mesenchymal stem cells. In addition to well established monolayer cell culture models, 3D cell cultures for stem cell-based osteogenic differentiation have become increasingly attractive to promote in vivo bone formation. One of the main problems of scaffold-based osteogenic cell cultures is the difficulty in quantifying the amount of newly produced extracellular mineral deposition, as a marker for new bone formation, without destroying the scaffold. In recent studies, we were able to show that ^99mTc-methylene diphosphonate (^99mTc-MDP), a gamma radiation-emitting radionuclide, can successfully be applied as a reliable quantitative marker for mineral deposition as this tracer binds with high affinity to newly produced hydroxyapatite (HA).

We studied the most superficial layer of macroscopically normal articular cartilage obtained from human femoral heads, using polarising microscopy and SEM. The most superficial layer, 4 to 8 microns thick, was acellular consisting of collagen fibrils. This layer could be peeled away as a thin film, with no broken collagen fibrils on its inferior surface or on the surface of subjacent cartilage layers. The orientation and diameter of collagen fibrils were different on these two surfaces. Our findings suggest that the most superficial layer is an independent one which is only loosely connected to the fibrous structure in the layer deep to it

We cultured human osteoblasts from trabecular bone explants and confirmed their phenotype by alkaline phosphatase assay, increased cyclic adenosine monophosphate production in response to prostaglandin E2 and radiographic micro-analysis of nodules of calcification. The osteoblasts were seeded on to demineralised human bone fragments and examined at ten-day intervals over a 50-day period by scanning electron microscopy. During this time the bank bone became progressively repopulated by the cultured osteoblasts. This system may offer a means of graft enhancement in elective orthopaedic and maxillofacial surgery by delivery of cultured autologous human osteoblasts to bone defects

Aims

Current treatments of prosthetic joint infection (PJI) are minimally effective against Staphylococcus aureus biofilm. A murine PJI model of debridement, antibiotics, and implant retention (DAIR) was used to test the hypothesis that PlySs2, a bacteriophage-derived lysin, can target S. aureus biofilm and address the unique challenges presented in this periprosthetic environment.

Ischaemic preconditioning is a process by which exposure of a tissue to a short period of non-damaging ischaemic stress leads to resistance to the deleterious effects of a subsequent prolonged ischaemic stress. It has been extensively described in the heart, but few studies have examined the possibility that it can occur in skeletal muscle. We have used a rat model of ischaemia of one limb to examine this possibility. Exposure of the hind limb to a period of ischaemia of five minutes and reperfusion for five minutes significantly protected the tibialis anterior muscle against the structural damage induced by a subsequent period of limb ischaemia for four hours and reperfusion for one hour. This protection was evident on examination of the muscle by both light and electron microscopy. Longer or shorter times of prior ischaemia had no effect

The ability to edit DNA at the nucleotide level using clustered regularly interspaced short palindromic repeats (CRISPR) systems is a relatively new investigative tool that is revolutionizing the analysis of many aspects of human health and disease, including orthopaedic disease. CRISPR, adapted for mammalian cell genome editing from a bacterial defence system, has been shown to be a flexible, programmable, scalable, and easy-to-use gene editing tool. Recent improvements increase the functionality of CRISPR through the engineering of specific elements of CRISPR systems, the discovery of new, naturally occurring CRISPR molecules, and modifications that take CRISPR beyond gene editing to the regulation of gene transcription and the manipulation of RNA. Here, the basics of CRISPR genome editing will be reviewed, including a description of how it has transformed some aspects of molecular musculoskeletal research, and will conclude by speculating what the future holds for the use of CRISPR-related treatments and therapies in clinical orthopaedic practice.

Cite this article: Bone Joint Res 2020;9(7):351–359.

Full thickness samples of articular cartilage were removed from areas of chondromalacia on the medial and "odd" facets of the patellae of 21 adults and examined by histology, autoradiography and electron microscopy. Surface fibrillation, loss of superficial matrix staining and reduced 35SO4 labelling was seen, with little change in the deep zone. Ten cases showed "fibrous metaplasia" of the superficial cartilage with definite evidence of cell division and apparent smoothing of the surface. Scattered chondrocyte replication appeared to occur in the surrounding intact cartilage. The findings suggest that early lesions in chondromalacia patellae may heal either by cartilage or fibrous metaplasia and that this may account for the resolution of clinical symptoms