Introduction

To evaluate the clinical success and hip pain and function of patients with infected hip replacement treated by two-stage exchange using a temporary implant with high dose vancomycin added to the antibiotic cement at the first stage revision.

Introduction

Articular hyaline cartilage has a unique structural composition that allows it to endure high load, distribute load to bone and enables low friction movement in joints. A novel acellular xenogenic graft is proposed as a biological cartilage replacement, for repair of osteochondral defects. Acellular porcine cartilage has been produced using repeated freeze thaw cycles and washing using hypotonic buffers and sodium dodecyl sulphate solution (SDS; Keir, 2008). DNA content of the acellular matrix was reduced by 93.3% compared to native cartilage as measured by nanodrop spectrophotometry of extracted DNA, with a corresponding reduction in glycosaminoglycan (GAG) content.

The purpose of this paper is to review the early results of Prostalac system under licence from Therapeutic Goods Administration for Professor Howie in the management of two stage exchange hip arthroplasty for infection (restricted to Royal Adelaide Hospital) and the addition of vancomycin and teicoplanin powder to tobramycin cement without additional tobramycin.

Thirteen patients were treated for an infected THR with the Prostalac system. Preoperative and intra-operative cultures were taken to identify the infective organisms. Vancomycin 3 gm was added to the Prostalac cement mantle per 40 gm packet of antibiotic bone cement containing tobramycin 1 gm. Teicoplanin 2.4 gm was used in one case where the patient had a known vancomycin allergy. Postoperatively patients underwent six weeks of IV antibiotics followed by four to six weeks of oral.

A short term successful clinical outcome was determined by implantation of a total hip prosthesis at the time of second stage operation and no reoperations resulting from recurrent infection and off antibiotics for â□¥ 6 months with normal clinical and CRP lab values.

Thirteen patients received the Prostalac system. No patient was lost to follow-up. Nine have progressed to second stage revision, eight of which had femoral impaction grafting. Two deaths occurred not attributed to the Prostalac system. Three superficial wound infections and two required washout and debridement. One Prostalac stem subsidence. There has been no recurrence of deep joint infection. Retention of the second stage prosthesis has been 100% at 17 months.

The PROSTALAC system with the addition of vancomycin or teicoplanin to the tobramycin antibiotic cement has encouraging short-term results for treatment of deep joint infection. Complication rate has been well within the range reported in literature. Successful early outcomes are encouraging with all patients in the Prostalac study having retained their permanent hip prosthesis following second stage surgery.

To review the accuracy of our systematic process in preventing wrong level lumbar microdiscectomy.

X-ray is used to identify the correct level for the skin incision to be made, x-ray is again used if the surgeon is in doubt prior performing the flavotomy. Following a lumbar microdiscectomy a Watson Chane is inserted into the empty disc space and an intra-operative x-ray is taken to confirm the level the discectomy has occurred. Observers A and B independently reviewed intra-operative x-ray in patients undergoing lumbar microdiscectomies and correlated the accuracy of the x-ray in determining correct level surgery against the pre-operative MRI scan and the preposed level of surgery.

123 patients, 66 males and 57 females underwent 127 lumbar microdiscectomy procedures between 2007 and 2009. The levels where surgery occurred are;- L2/3 -1 patient, L3/4–8 patients, L4/5–53 patients and L5/S1-65 patients.

Kappa coefficient was used to determine inter-observer and Pearson Correlation coefficient was used to determine the X-ray and MRI relationship

Percentage of patients who required a pre-flavotomy x-ray level check are:- L2/3–100%, L3/4-63%, L4/5–45%, and L5/S1–40%. Pearson's correlation in confirming the level lumbar microdiscectomy was performed using final x-ray and the pre-operative MRI scan was 1. Kappa coefficient between observer A and B was 1.

This process of using intra-operative x-ray in determining the exact level where lumbar microdiscectomy was performed is 100% accurate. This is our standard process in preventing wrong level surgery for lumbar microdiscectomy.

Introduction: The aim of this study was to develop a technique to decellularise a porcine cartilagebone construct with a view to using this as a biological scaffold for transplantation into human osteochondral defect as a cartilage substitute.

Methods: Decellularisation was based on a modification of the technique of Booth et al (2002). Cartilage bone matrix (n=9) were decellularised by exposing the tissue to 2 cycles of dry freeze-thaw followed 2 more cycles with the addition of hypotonic (10mM tris-HCl, pH8.0) buffer. Samples were then cycled through hypotonic buffer, followed by ionic detergent (0.1% [w/v] sodium dodecyl sulphate [SDS]) in the presence of protease inhibitors (aprotinin 10 KIU/ml) and 0.1% (w/v) ethylene diamine tetraacetic acid (EDTA). This was followed by washes in PBS with aprotinin and incubation in nuclease solution containing DNase (50U/ml) and RNase (1U/ml). Decontamination using 0.1% (v/v) peracetic acid in PBS was then incorporated to achieve disinfection of the tissue samples. Finally, samples were washed in PBS. Three decellularisation protocols were used depending on the number of hypotonic/SDS cycles: this was either done once, three or six times referred to as DC1, DC3 and DC6 respectively. Fresh & decellularised cartilage were compared histologically using haematoxylin and eosin staining, to visualize cellular content, sirius red, to visualise collagen fibres & alcian blue, to visualise glycosaminoglycans (GAG). Immunohistochemistry staining for galactose-α-1,3-galactose (α-gal), collagen I, II & VI was performed for fresh and decellularised samples. DNA assay: Genomic DNA was extracted using a DNA isolation kit for tissues (Roche Applied Sciences). Collagen and DMB sulphated sugar assay, as described by Stapleton et al. (2008), were performed to measure collagen and GAG content. The biphasic property of fresh and decellularised cartilage was determined using a pin on plate indentation test.

Results: H& E staining revealed the absence of visible whole cells. Sirius red stain gave evidence of the retention of collagen following decellularisation. In contrast, the acellular matrix showed evidence of loss of GAGs. There was no evidence of the expression of α-gal in the acellular scaffold. DNA analysis revealed the absence of genomic DNA in comparison to fresh tissues (ANOVA, p< 0.05). The decellularisation process had minimal effect on the collagen content of the cartilage. Nevertheless there was a significant difference in the sulphated sugar content of the fresh tissue when compared to the decellularised tissue (ANOVA, p< 0.05), indicating loss of 92% GAG. Biomechanical testing of decellularised tissues showed a significant change (ANOVA, p< 0.05) in comparison to the fresh cartilage.

Discussion: In conclusion this study has generated data on the production of an acellular cartilage bone matrix scaffold for use in osteochondral defect repair. To our knowledge, this is the first study that has successfully removed whole cells and α-gal from xenogeneic cartilage and bone tissue. Future studies are required to investigate methods to recellularise the acellular matrix using an appropriate cell type and mechanical conditioning and to investigate replenishing GAG loss following decellularisation.

Introduction: UHMWPE wear debris is known to be a major cause of periprosthetic osteolysis and the long-term failure of total joint replacements by a macrophage-mediated mechanism. The aim of this study was to compare the in vitro response of mononuclear phagocytes from patients undergoing total hip arthroplasty to challenge with polyethylene particles or stimulation with lipopolysaccharide (LPS).

Methods: Peripheral blood was taken from 2 healthy donors and 16 patients admitted to hospital to undergo total hip arthroplasty. Human mononuclear phagocytes were isolated by density centrifugation. Polyethylene particles were sequentially filtered to obtain biologically active particles (0.1–0.6 μm diameter). Cells plus particles, cells plus LPS and cells only were co-cultured in supplemented RPMI-1640 culture medium. Culture supernatants were harvested and the concentration of TNFα quantified by ELISA. Mean specific activity was calculated.

Results:.

When considering all the subjects, no correlation was found between the response of their cells to polyethylene particles and LPS stimulation. However the cells of four subjects gave a much higher response to LPS than the rest and when these where excluded the correlation between the response to LPS and PE particles was significant with an R² value of 0.9076.

Discussion: Despite the different mechanisms by which PE particles and LPS activate macrophages, the patient group with ‘normal’ or low response to LPS had a significant correlation in their response to LPS and particle stimulation. Why a small number of subjects had a much higher response to LPS without a proportional response to PE particles is not known, but it could be due to an increased expression of LPS receptors or genetic polymorphism. A greater than ten-fold difference in the patient response to particles may be of clinical importance in their potential susceptibility to loosening through osteolysis.