Currently long term survivorship is highly predictable for total knee replacements. However, they still do not have the functional outcome of a normal knee, particularly in younger people. Using our results published in 1999 we compared the functional outcomes with a modern design implant.

415 patients having an LPS Flex Mobile implant were performed by one surgeon and were assessed using the SF36 functional outcome questionnaire. Patients were looked at pre-operatively, three months post-operatively and 12 months post-operatively. The results were compared with the previously reported study and there were shown to be some exciting changes in respect to functional outcome, particularly in the younger age group, and at the same time not incurring any increased complications. Comparing the 2 studies in 1999 and this study and using the ABS survey where population norms were calculated we showed that the results in the older patients were maintained with no additional compllcations. In 1999 the younger patients performed poorly however in this new study the younger patients returned to the age matched expected norms for the broader community.

Total knee replacements still do not provide normal function in a knee, however, recent changes to design concepts have permitted improved functional outcome for patients particularly in the younger age group.

Current orthopaedic practice involves an increasing use of operative fluoroscopic screening and radiation exposure. The AOA produces a booklet entitled “Radiation safety for orthopaedic surgeons” outlining the risks. There is a disparity between guidelines and actual clinical practice for trainee registrars.

Aims:

To measure trainee fluoroscopy usage with and without consultants present.

All procedures in a 6 month period using II were analysed. Data for Procedure, Operating Surgeon, First Assistant and if Consultant Surgeon was present or absent was collected. Fluoroscopic Exposure Time was also recorded.

Procedures were grouped and times compared depending on the staff present. There were 121 cases included in the study. 44 cases were performed by the trainee with the consultant assisting and 76 were performed in the absence of the consultant.

A questionnaire based on the AOA guidelines was produced. All NSW advanced trainees in Orthopaedic surgery were asked to complete the anonymous questionnaire.

There was a significant difference of 32.18 seconds in mean exposure time per case with a p-value 0.0069 where the consultant was present or not. There was also a significant difference between consultants doing the same cases.

Other very significant findings were:

97% of trainees were not aware of the maintenance and inspection schedules equipment.

One registrar was exposed to 8131 seconds of II exposure during his 6 month rotation. Without the use of lead protection, the trainee registrar will have exceeded the annual limit of whole body exposure (20mSv/year) by more than 2-fold.

Dramatic decreases in exposure can be achieved by better discipline with the usage of II. This needs to be a fundamental part of registrar training.

The survey shows trainees are not aware, or fail to adhere to current guidelines and that hospitals are not providing appropriate safety equipment and not insisting that staff exercise safe practices.

Introduction and Aims: While clinical variables are considered important risk factors for post-arthroplasty VTE, the role of common genetic thrombophilic factors is less clear. The aims of this study were to determine if common thrombophilic genetic polymorphisms are independent risk factors for VTE post-arthroplasty; and if clinical variables are equally or more important.

Method: A prospective study of consecutive patients undergoing elective total hip or knee arthroplasty at a single institution, involving two surgeons. Patients were interviewed to assess clinical risks. Pre-operative blood samples were taken for Factor V Leiden (FVL), Pro-thrombin G20210A (PTH) and Methylenetetrahydrofolate reductase C677T (MTHFR) testing. All patients received routine enoxaparin prophylaxis and compression stockings. Intermittent pneumatic calf compression was also used by one surgeon. Presence of DVT was assessed using bilateral lower limb duplex ultrasonography (seven ± two days post-operatively) in all patients and performed in a vascular laboratory. Symptoms suggestive of pulmonary embolism were investigated by ventilation/perfusion lung scanning.

Results: A total of 569 patients were recruited with a median age of 67 years (range 20–90). Osteoarthritis was the main surgical indication. The overall incidence of post-operative venous thromboembolism (VTE) was 26%. Of thromboembolic events, 15% VTE were proximal DVT; 84% VTE were distal DVT and only one percent were pulmonary emboli. Prevalence of the thrombophilic genotypes was: 4.6% (heterozygous FVL mutation); 2.1% (heterozygous PTH); and 10.4% (homozygous C677T MTHFR mutation). Using univariate analysis, older age (p < 0.0005), total knee arthroplasty (p < 0.0005), recent surgery (p = 0.002), general anaesthesia (p = 0.013), operation time in minutes (p < 0.0005) and use of blood transfusions (p < 0.0005) were significantly associated with post-operative DVT. None of the thrombophilic genotypes were found to be significantly associated with post-operative DVT, however the frequency of FVL and PTH was highest in patients with proximal DVT and total hip arthroplasty patients with DVT. In multivariate analysis of both genetic and clinical thrombophilic factors, only age (p=0.02) and total knee arthroplasty (p< 0.0005) were found to be significant independent risk factors for post-operative VTE.

Conclusion: We conclude that clinical factors such as age and type of surgery (total knee arthroplasty) are independent risks for post-operative VTE in patients undergoing lower limb arthroplasty. FVL, PTH and MTHFR are not significant risk factors for post-operative VTE and screening for these mutations is not indicated.

Introduction and Aims: Aberrations in the balance of chondrocyte metabolism play an integral role in the degeneration of articular cartilage and subsequent osteoarthritis. Gene expression profiling allows a comparison of levels of mRNA expression in large numbers of genes simultaneously. This study compares the mRNA expression from osteoarthritic cartilage in knees and hips with that of normal cartilage.

Method: Human cartilage samples were obtained from osteoarthritic knees and hips at the time of joint arthroplasty surgery. ‘Normal’ cartilage was obtained from femoral heads after fracture or from radial heads after trauma. Cartilage samples were either snap frozen in liquid nitrogen or enzymatically digested and established in primary cell culture prior to RNA isolation. The RNA was reverse-transcribed to cDNA, labelled with a fluorochrome and then hybridised to gene chips.

Results: In addition to confirming that cells raised in primary cell culture dedifferentiate to a fibroblast-like state and cease to synthesise normal products of cartilage matrix we have also developed a reproducible method of processing snap frozen cartilage samples in order to produce a sufficiently pure quantity of mRNA to be used in gene chip technology. We now have gene chips completed for a ‘normal’ control, a standard osteo-arthritic knee and an osteoarthritic hip with a significant genetic history of early onset osteoarthritis. Early analysis and comparison of the data from these chips identifies some potential candidate genes for further analysis.

Conclusion: Human articular cartilage lends itself to gene profiling using cDNA arrays as it contains only one cell type. Thus any changes in gene expression levels can be directly attributable to the chondrocyte. This early data analysis opens the door to a new search for the ‘arthritis gene’. For the data to be meaningful we will need to process gene chips on several more samples of arthritic and ‘normal’ cartilage.

Introduction Aberrations in the balance of chondrocyte metabolism play an integral role in the degeneration of articular cartilage and subsequent arthritis. Gene expression profiling is a powerful tool which allows identification of differences in levels of mRNA expression of large numbers of genes simultaneously. The objective of this study was to compare mRNA expression from osteoarthritic cartilage with that of normal cartilage and by use of the Affymetrix system, identify target genes for further investigation.

Methods Human cartilage samples were obtained from osteoarthritic knees and hips at the time of joint replacement surgery. Non-arthritic cartilage samples were obtained from notchplasty at time of cruciate ligament replacement surgery or from trauma surgery. Cartilage samples were either snap frozen in liquid nitrogen and RNA directly isolated from the frozen tissue or enzymatically digested and established in primary culture prior to RNA isolation. The RNA was reverse transcribed to cDNA, labelled with a fluorochrome and then hybridised to gene chips. This will allow us to: 1. Compare whether RNA expression in cell culture accurately reflects that in the tissue itself. 2. Determine whether there are differences between the gene profiles of knee and hip osteoarthritis. 3. Select candidate genes for further analysis.

Results At present primary cell culture lines have been successfully established and are ready for RNA isolation. Frozen cartilage samples have undergone RNA isolation. Currently techniques are underway to maximise RNA extraction and sufficiently purify it to process a gene chip. Once the gene chip is made a list of up or down-regulated genes will be available for analysis. Human articular cartilage lends itself to gene profiling using cDNA arrays as it contains only one cell type. Thus any changes in gene expression levels can be directly attributed to the chondrocyte.

Conclusions This technology opens the door to a new search for the ‘arthritis gene’.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.

Aim: To determine the pattern of gene expression induced in cultured human chondrocytes in response to compressive mechanical loads.

Methods: Chondrocytes were obtained from tissue discarded at the time of a number of total knee replacements and where established in primary cell culture. The cultured chondrocytes were then subjected to compressive and tensile loads using a Flexcell machine. The RNA was subsequently extracted from these chondrocytes and the alterations in gene expression determined using the Affymetrix Gene Array machine.

Results: Intended as an in vitro model for Osteoarthritis, it was found that mechanical stimulation of human chondrocytes caused a significant alteration in the expression of a number of classes of compounds. These included enzymes, inflammatory mediators and structural proteins.

Conclusions: This study identified several interesting candidate genes whose expression was significantly altered after being exposed to a laboratory model for osteoarthrosis. Further study of these genes and their expression may lead to important clinical applications.