Introduction

The biological pathways responsible for adverse reactions to metal debris (ARMD) are unknown. Necrotic and inflammatory changes in response to Co-Cr nanoparticles in periprosthetic tissues may involve both a cytotoxic response and a type IV delayed hypersensitivity response.

Our aim was to establish whether differences in biological cascade activation exists in tissues of patients with end-stage OA compared to those with aseptic loosening of a metal on polyethylene (MoP) THR and those with ARMD from metal-on-metal (MoM) THR.

Summary Statement

Dickkopf-3 is upregulated in OA cartilage and synovial tissue. In vitro studies show Dkk3 can prevent cartilage degradation and antagonise Wnt signaling. We hypothesis that Dkk3 can protect against OA-related cartilage destruction.

The purpose of this study was to profile the mRNA expression for the 23 known matrix metalloproteinases (MMPs), 4 tissue inhibitor of metalloproteinases (TIMPs) and 19 ADAMTSs (a disintegrin and metalloproteinase with thrombospontin motif) in Dupuytren's Disease and normal palmar fascia.

Dupuytren's Disease (DD) is a fibroproliferative disorder affecting the palmar fascia, leading to contractures. The MMPs and ADAMTSs are related enzymes collectively responsible for turnover of the extracellular matrix. The balance between the proteolytic action of the MMPs and ADAMTSs and their inhibition by the TIMPs underpins many pathological processes. Deviation in favour of proteolysis is seen in e.g. invasive carcinomata, whereas an imbalance towards inhibition causes e.g. fibrosis. A group of patients with end-stage gastric carcinoma was treated with a broad spectrum MMP inhibitor in an attempt to reduce the rate of carcinoma advancement; a proportion developed a ‘musculoskeletal syndrome’ resembling DD.

Tissue samples were obtained from patients undergoing surgery to correct contractures caused by DD and from healthy controls undergoing carpal tunnel decompression. The DD tissue was separated macroscopically into cord and nodule. Total RNA was extracted and mRNA expression analysed by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), normalised to 18S rRNA. Comparing across all genes, the DD nodule, DD cord and normal palmar fascia samples each had a distinct mRNA expression profile. Statistically significant (p<0.05) differences in mRNA expression included: higher MMP-2, -7 and ADAMTS-3 levels in both cord and nodule; higher MMP-1, -14, TIMP-1 and ADAMTS-4 and -5 in nodule alone, lower MMP-3 in nodule and cord and lower TIMP-2, -3 and -4 and ADAMTS-1 and -8 levels in nodule alone.

The distinct mRNA profile of each group suggests differences in extracellular proteolytic activity which may underlie the process of fascial remodelling in DD.

The most frequent cause of failure after total hip replacement in all reported arthroplasty registries is peri-prosthetic osteolysis. Osteolysis is an active biological process initiated in response to wear debris. The eventual response to this process is the activation of macrophages and loss of bone.

Activation of macrophages initiates a complex biological cascade resulting in the final common pathway of an increase in osteolytic activity. The biological initiators, mechanisms for and regulation of this process are beginning to be understood. This article explores current concepts in the causes of, and underlying biological mechanism resulting in peri-prosthetic osteolysis, reviewing the current basic science and clinical literature surrounding the topic.

Classification of osteoarthritis of the hip is fraught with difficulty Although different patterns of disease are recognised, there is no accepted classification or grading system. We aim to develop a classification system that reflects both the radiological changes, and the local disease process within the joint.

After ethical permission and consent tissue was taken from 20 patients undergoing primary hip replacement surgery. Intra-operative tissue samples were taken from each patient and the steady state gene expression of several cytokines (TNF-α, IL1-β, IFN-γ, IL-6, RANKL and OPG) measured quantitatively using Taqman RT-PCR. Relative expression was calculated for each sample using standard curves and normalised to 18S expression. The technique was consistent with high correlations for repeated measures from the same tissue type (κ=0.99) and from different tissue types in the same joint (κ=0.92). Intra-observer (κ=0.93) and inter-observer (κ=0.89) reliability for the technique were also found to be high.

Preoperative radiographs were scored by two independent observers and joint space narrowing, cysts, osteophytes and sclerosis noted in each of the DeLee-Charnley zones on the femoral and acetabular side. Based on these scores patients were then classified to either lytic or sclerotic type and subclassified into either hypertrophic or atrophic.

Subgroup analysis of cytokine expression by radiographic type was performed. There were statically significant differences in expression of macrophage stimulating cytokines (IL-1γ and OPG) in the lytic group as compared to the sclerotic group (p< 0.05). Conversely, the sclerotic group expressed significantly higher levels of IL-6. Individuals with atrophic subtype demonstrated significantly higher levels of IL-1β and IL-6, but lower levels of IFN-γ

Our results demonstrate greatly differing patterns of disease within osteoarthritic hip joints. These changes are reflected in radiographic appearances of osteoarthritis. Our proposed classification system can be used grade and classify osteoarthritis in a manner that reflects the disease process.

Our aim was to investigate the molecular features of progressive severities of cartilage damage, within the phenotype of Anteromedial Gonarthrosis (AMG).

Ten medial tibial plateau specimens were collected from patients undergoing unicompartmental knee replacements. The cartilage within the area of macroscopic damage was divided into equal thirds: T1(most damaged), to T3 (least damaged). The area of macroscopically undamaged cartilage was taken as a 4th sample, N. The specimens were prepared for histological (Safranin-O and H& E staining) and immunohistochemical analysis (Type I and II Collagen, proliferation and apoptosis). Immunoassays were undertaken for Collagens I and II and GAG content. Real time PCR compared gene expression between areas T and N.

There was a decrease in OARSI grade across the four areas, with progressively less fibrillation between areas T1, T2 and T3. Area N had an OARSI grade of 0 (normal). The GAG immunoassay showed decreased levels with increasing severity of cartilage damage (p< 0.0001). There was no significant difference in the Collagen II content or gene expression between areas. The Collagen I immunohistochemistry showed increased staining within chondrocyte pericellular areas in the undamaged region (N) and immunoassays showed that the Collagen I content of this macroscopically and histologically normal cartilage, was significantly higher than the damaged areas (p< 0.0001). Furthermore, real time PCR showed a significant increase in Collagen I expression in the macroscopically normal areas compared to the damaged areas (p=0.04).

In AMG there are distinct areas, demonstrating progressive cartilage loss. We conclude that in this phenotype the Collagen I increase, in areas of macroscopically and histologically normal cartilage, may represent very early changes of the cartilage matrix within the osteoarthritic disease process. This may be able to be used as an assay of early disease and as a therapeutic target for disease modification or treatment.

The aim of this study was to investigate the molecular features of progressive severities of cartilage damage, within the phenotype of Anteromedial Osteoarthritis of the Knee (AMOA).

Ten medial tibial plateau specimens were collected from patients undergoing unicompartmental knee replacements. The cartilage within the area of macroscopic damage was divided into equal thirds: T1(most damaged), to T3 (least damaged). The area of macroscopically undamaged cartilage was taken as a 4th sample, N. The specimens were prepared for histological (Safranin-O and H& E staining) and immunohistochemical analysis (Type I and II Collagen). Immunoassays were undertaken for Collagens I and II and GAG content. Real time PCR compared gene expression between areas T and N.

There was a decrease in OARSI grade across the four areas, with progressively less fibrillation between areas T1, T2 and T3. Area N had an OARSI grade of 0 (normal).

The GAG immunoassay showed decreased levels with increasing severity of cartilage damage (ANOVA P< 0.0001). There was no significant difference in the Collagen II content or gene expression between areas. The Collagen I immunohistochemistry showed increased staining within chondrocyte territorial areas in the undamaged region (N) and immunoassays showed that the Collagen I content of this macroscopically and histologically normal cartilage, was significantly higher than the damaged areas (ANOVA P< 0.0001). Furthermore, real time PCR showed that there was a significant increase in Collagen I expression in the macroscopically normal areas (p=0.04).

In AMOA there are distinct areas, demonstrating progressive cartilage loss. We conclude that in this phenotype the Collagen I increase, in areas of macroscopically and histologically normal cartilage, may represent very early changes of the cartilage matrix within the osteoarthritic disease process. This may be able to be used as an assay of early disease and as a therapeutic target for disease modification or treatment.

The matrix metalloproteinases (MMPs) and ADAMTSs (a disintegrin and metalloproteinase with thrombos-pontin motif) are related enzymes collectively responsible for turnover of the extracellular matrix. The balance between the proteolytic action of the MMPs and ADAMTSs, and their inhibition by the tissue inhibitors of metalloproteinases (TIMPs), underpins many pathological processes. Deviation in favour of proteolysis is seen in e.g. invasive carcinoma, whereas an imbalance towards inhibition causes e.g. fibrosis.

Dupuytren’s Disease (DD) is a fibroproliferative disorder affecting the palmar fascia, leading to contractures. A group of patients with end-stage gastric carcinoma were treated with a broad spectrum MMP inhibitor in an attempt to reduce the rate of tumour advancement: a proportion developed a ‘musculoskeletal syndrome’ resembling DD. Several groups have looked at subsets of the metalloproteinase family in relation to DD, but to date, a study of the gene expression of all of the members has not been published. We therefore set out to profile the mRNA expression for the 23 known MMPs, 4 TIMPs & 19 ADAMTSs in DD and normal palmar fascia.

Tissue samples were obtained from patients undergoing surgery to correct contractures caused by DD and from healthy controls undergoing carpal tunnel decompression. The DD tissue was separated macroscopically into cord and nodule. Total RNA was extracted and mRNA expression analysed by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), normalised to 18S rRNA. Comparing across all genes, the DD nodule, DD cord and normal palmar fascia samples each had a distinct mRNA expression profile. Statistically significant (p< 0.05) differences in mRNA expression included: higher MMP-2, -7 and ADAMTS-3 levels in both cord and nodule; higher MMP-1, -14, TIMP-1 and ADAMTS-4 and -5 in nodule alone, lower MMP-3 in nodule and cord and lower TIMP-2, -3 and -4 and ADAMTS-1 and -8 levels in nodule alone.

The distinct mRNA profile of each group suggests differences in extracellular proteolytic activity which may underlie the process of fascial remodelling in DD. Further in vitro experiments are planned based on these observed differences in gene expression.