The Osteoprotegerin/RANK/RANKL system has been implicated in the biological cascade of events initiated by particulate wear debris and bacterial infection resulting in periprosthetic bone loss around loosened total hip arthroplasties (THA). Individual responses to such stimuli may be dictated by genetic variation and we have studied the effect of single nucleotide polymorphisms (SNPs) within these genes.

We performed a case control study of the Osteoprotegerin, RANK and RANKL genes for possible association with deep sepsis or aseptic loosening. All patients included in the study were Caucasian and had had a cemented Charnley THA and polyethylene acetabular cup. Cases consisted of 91 patients with early aseptic loosening and 71 patients with microbiological evidence at surgery of deep infection. Controls consisted of 150 THAs that were clinically asymptomatic for over 10 years and demonstrated no radiographic features of aseptic loosening. DNA samples from all individuals were genotyped using Taqman allelic discrimination.

The A allele (p<0.001) and homozygous genotype A/A (p<0.001) for the OPG-163 SNP were highly associated with aseptic failure. Additionally, the RANK-575 (C/T SNP) T allele (p=0.004) and T/T genotype (p=0.008) frequencies were associated with aseptic failure. No statistically significant relationship was found between aseptic loosening and the OPG- 245 or OPG-1181 SNPs.

When the septic group was compared to controls, the frequency of the A allele (p<0.001) and homozygous genotype A/A (p<0.001) for the OPG-163 SNP were statistically significant. No statistically significant relationship was found between septic failure and the OPG- 245, OPG-1181 or RANK-575 SNPs.

Aseptic loosening and possibly deep infection of THA may be under genetic influence to candidate susceptibility genes. SNP markers may serve as predictors of implant survival and aid pharmacogenomic prevention of THA failure.

Aim: To identify the microbiology of infected knee arthroplasty, emerging patterns of resistance over the last decade, and suggest appropriate empirical treatment.

Methods: A retrospective analysis was conducted of 121 patients with microbiologically proven infection, who underwent revision TKA between 1994–2008. The causative organism was identified from microbiological samples and the corresponding sensitivities recorded. The data was then collated to determine the most common causative organisms, changing patterns of antibiotic resistance over the time frame, and the antibiotics currently most effective at treating deep infection. A theoretical model combining gentamicin with other antibiotics was used to determine the most effective antibiotics for use as empirical treatments.

Results: Coagulase negative Staphylococcus (CNS) was the most common causative organism (49%). Staphylococcus aureus (SA) accounted for 13% of cases. The prevalence of CNS appears to be increasing, while that of SA and other organisms is decreasing. Vancomycin and teicoplanin were the most effective antibiotics with overall sensitivity rates of 100% and 96% respectively. Levels of resistance were significantly higher among the antibiotics commonly used in the community. Antimicrobial resistance was higher when the causative organism was CNS, suggesting that MRSE is becoming a problem in knee arthroplasty. Our theoretical model showed that gentamicin combined with vancomycin would be the most effective empirical treatment.

Conclusion: Understanding the microbiology of deep infection of the knee allows surgeons to treat this complication as effectively as possible. Vancomycin and tei-coplanin appear to be the most effective antimicrobials, with relative invulnerability to the development of resistance. Given the effectiveness of these antibiotics, the use of vancomycin in gentamicin bone cement, combined with IV teicoplanin potentially allows for infected knee arthoplasties to be treated with a one-stage procedure. The rational use of antibiotics may help limit the amount of antibiotic resistance which develops in the future.

Patients with a history of septic arthritis or tuberculosis (TB) of the hip frequently develop secondary osteoarthritis (OA). These patients present a challenge for having joint replacement because of abnormal bone development, the possibility of re-infection, soft tissue problems and their life-style (more active than patients with old age arthritis). We retrospectively review a decent group of 55 cases where one stage cemented total hip arthroplasty was performed with history of old hip infection by a team of surgeons at Wrightington Hospital, Lancashire, UK from 1970 to 2008. The purpose of this study is to find the survival analysis with revision (for infection) as the end stage. There are 33 females and 22 males aged from 25 to 75 yrs (mean 52 years). 21 patients had proven or probable tuberculous infection, 29 had the past history of old septic hip, and the remaining 5 had recent septic hip (i.e., less than 5 years). The patients are followed for between 1 to 23 years (mean 10 years). Pre-operatively, 25 patients had arthrodesis while 24 patients had moderate to severe secondary OA. 3 patients had dysplastic acetabulum, 2 patients had shallow acetabulum and 1 had Avascular Necrosis (AVN). In 33 cases, intra-operative tissue samples didn’t grow any organism, 2 samples grew Staphylococcus aureus, 2 samples grew Coagulase Negative Staphylococcus (CNS), 1 grew pseudomonas, samples were not sent in 9 cases, laboratory did not process the sample in 1 case and no documentation found in 3 cases. Cement with antibiotics was used in 45 patients (Gentamicin alone in 37 cases, Gentamicin and Vancomycin in 3 cases, Gentamicin, Fucidic Acid and Eryth-romycin in 2 patients, Gentamicin, Vacncomycin and Streptomycin in 1 patient, Gentamicin and Streptomycin in 1 case and Gentamicin, Vacncomycin and Amoxycillin in 1 patient). Mostly intravenous antibiotics (3 doses of Cefuroxime) were given, but in few cases with old TB, anti-tuberculous treatment was started pre-operatively and continued for 3 months post-op. In 16 patients either antibiotics were not given or not documented to be given. Failure happened in 2 cases of positive intra-op sample culture with Staphylococcus aureus, 1 patient with pre-op aspiration which showed pseudomonas and in 2 cases where tissue sample showed no growth. 8 patients had revision of at least one of the components for aseptic loosening. The 2 failed cases with positive culture with Staphylococcus aureus had post operative antibiotics and extra antibiotics in cement. Both cases had early wound healing issues.

Conclusion: We can conclude that total hip arthroplasty is safe in old cases of septic or tuberculous hips, provided appropriate antibiotic cover. We have some evidence that total hip replacement can be carried out in cases of recent infection of hip but level of evidence is not very great as we don’t have a large sample of such patients.

‘Force-closed’, tapered, polished, collar-less stems, (e.g. C-stem, Exeter), are designed to subside in response to expansion of the cement/bone complex over time. Above a certain threshold, distal migration may predict medium-to-long-term failure of ‘shape-closed’ stems. However, no such threshold exists for ‘force-closed’ stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively, could be the best predictor of good long-term performance.

Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via a posterior approach: 17, and a lateral, trochanteric approach: 3. RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs. At 36M the mean stem centroid subsidence was 1.05 mm and had levelled off to a low rate. The mean internal rotation of 2.5° at 36M had not significantly changed during the final year (p = 0.08).

At 36M the mean posterior migration of the stem centroid was 0.54 mm (rate of 0.11 mm/y) and posterior migration of the femoral head was 1.66 mm (rate of 0.25 mm/y).

At 36M the mean subsidence rate was very low and the mean posterior migration was about one third of that reported for another RSA study of the C-stem. Although the mean internal rotation was greater than that reported for the Exeter stem, there was no significant change during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component.

Infection in total knee replacement is a devastating complication. Current literature supports two-stage revision as the gold standard treatment. The alternative single stage procedure has been reported to have favourable results. We assessed the early clinical results of single stage revision for infected total knee replacement.

Between February 2005 and August 2007, 12 patients had revision total knee replacement for infection by the senior authors at two centres. In the majority of the patients, the infective organism was isolated by arthroscopic synovial biopsy prior to revision. Standard single stage procedure included the explantation, debridement and re-implantation of the prosthesis. All the patients received intravenous antibiotics for six weeks and oral antibiotics were continued for further 6 weeks. All the patients had the inflammatory markers monitored during follow-up.

Significant improvement was noted in the SF-12 PCS, WOMAC pain and stiffness scores at the latest follow-up. None of these patients required re-revision. Radiological evaluation was done using the Knee Society system. None of the knees showed evidence of progressive loosening. Radio-opaque lines were found around the stems and were present on immediate post-operative radiographs; this did not indicate loosening or infection at a mean follow-up of two years.

Early clinical and radiological results of the single stage revision for infected total knee replacement appear to be promising. One operation, one anaesthetic and quicker recovery are the advantages for the patient and with the reduced hospital stay it is cost-effective. The problems of stiffness in the knee and muscle wasting with cement spacer are avoided.

Background: Since Sir John Charnley introduced bio-clean air operating techniques such as the “body exhausting” system and a bio-clean air operating theatre to reduce the risk of infection3), total hip replacement has become one of the safest and most successful procedures in orthopaedic surgery and has benefited numerous people suffering from arthritis all over the world. However, deep infection is still undoubtedly one of the most serious complications after total hip arthroplasty (THA). It is still controversial whether one or two stage revision should be indicated for deeply infected hip replacement.

Purpose: The aim of this study was to identify the influential factors in one stage revision THA for deep infection with a long-term follow-up.

Methods: One stage revision THA for deep infection was carried out in 273 joints on 262 patients by the senior author between 1974 and 2000. All infected hip replacements were primarily treated with one stage revision THA regardless of micro organisms at the authors’ unit as far as sufficient bone stock for socket fixation was available in the acetabulum. This study included 162 revisions in 154 patients for which a minimum follow-up of five years (range 5 to 28 years; average 12.3 years) had been done. Fifty-two cases (32.1 %) had had discharging sinus by the time of revision surgery for infection.

Results: One hundred and thirty eight (85.2 %) hips were free of infection at the time of the latest follow-up. Twenty cases (12.3 %) had reoperation for recurrent infection. Four hips (2.5 %) maintained their implants with the evidence of infection. Twenty-two cases (13.6 %) showed radiological loosening. Thirteen cases (8.0 %) were revised again for reasons other than infection (12 for aseptic loosening and one for dislocation). Bone stock did not have significant influence on infection control while it did affect mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection. Neither discharging sinus nor gram-negative microorganism was considered as a contraindication.

Conclusion: This study presented the longest follow-up with a large number of cases in revision THA for deep infection. The results suggested that shielding medullary space with antibiotic-loaded cement was important for treatment of infected THA.

Introduction: “Force-closed”, tapered, polished, collarless stems, (e.g. C-stem, Exeter), are designed to subside in response to a gradual expansion of the cement/bone complex.

Above a certain threshold, distal migration may predict medium-to-long-term failure of “shape-closed” (collared, textured) stems. However, no such threshold exists for “force-closed” stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively could be the best predictor of good long-term performance.

Method: Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-Stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via: a posterior approach (17), and a lateral, trochanteric approach (3). RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs.

Results: By 36M the mean stem subsidence (1.05 mm) had levelled off to a low rate, and the mean internal rotation (2.5°) had not significantly changed during the final year (p = 0.08). The mean posterior migration of the stem centroid was 0.54 mm and posterior migration of the femoral head was 1.66 mm (0.25 mm/y during final year).

Discussion: At 36M the mean subsidence rate was very low, and the mean posterior migration was about one third of that reported by Sundberg et al. (BHS Meeting, 2007). Although the mean internal rotation was greater than that reported for the Exeter stem, it had stabilised during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component.

Introduction: The tribiological properties of bearing surfaces are one of the main topics in discussion in the orthopaedic research. Hard-on-hard bearings are one of the ways to reduce wear rates. Modern hard-on-hard bearing low wear rates depend on the correct pairing of bearing surfaces and strict manufacturing tolerances in surface roughness, clearance, and roundness.

There have been some concerns in using ceramic bearings, particularly regarding the fracture rate and their subsequent management. Hence, we present here 2 similar cases that highlight the catastrophic failure of metal head when used subsequently to treat the complication of ceramic fractures in Total Hip Arthroplasty (THA).

Case Details: Two patients underwent primary THA at different centres with ceramic-on-ceramic bearing. After an initial asymptomatic period of 2 years, ceramic fracture occurred in both the cases, which were subsequently replaced by metal-on-polyethylene bearings by the primary surgeons. One year after the revision of bearings, both the patients developed severe pain and discomfort, which on further investigation revealed massive metallosis, wear of the metal head and aseptic loosening of the acetabular components with cavitation in acetabulum.

Both the patients underwent revision THA under the senior author at our tertiary centre-Wrightington Hospital. Intraoperatively near total erosion of the metal head was noted with more than one litre of black, dense material collection in and around the hip joint revealing extensive metallosis. The acetabular cup was grossly loose and significant loss of bone stock was noted due to metallosis.

Single stage revision surgery was performed with impaction bone grafting for deficient acetabulum and cemented components were used. At one-year follow-up none of the cases have shown any further wear or complications.

Conclusion: One of the main objectives of successful THA is to improve implant longevity. To achieve this understanding the mechanisms of wear between the interacting surfaces is extremely important. The use of ceramic head is good, but there is always a risk of fracture. We do not recommend using metal heads in cases with prior ceramic fractures, as the wear of metal is most likely to occur as it is an ongoing process due to the residual ceramic debris. Hence in these difficult scenarios we recommend usage of ceramic-on-polyethylene as a safe option to prevent catastrophic erosion of metal head and improve implant longevity.

Introduction: The evolving pattern of bacterial resistance at septic revision surgery to the common antibiotics used during total hip arthroplasty is described.

Methods: A retrospective review of 72 case notes and microbiology data inclusive of bacterial sensitivity profiles was undertaken between January 2002 and April 2007. Data collected was combined with a previous study to demonstrate bacteriology trends over the last thirty years (327 cases). Antibiotic sensitivities to the two common infectious agents, Staphylococcus aureus and coagulase negative staphylococi were formulated into a hypothetical model combined with Gentamycin sensitivity, a constant factor (the sole antibiotic in bone cement), to assess the efficacy of the combination of antibiotics used in primary arthroplasty.

Results: When compared to previous microbiology data percentage isolates of each bacterium were found to be similar, confirming that the infectious agents at septic revision had remained the same, and were the common contaminants at primary surgery. The results also demonstrated an overall trend of increased resistance of the major organisms to the major classes of antibiotics used. Staphylococcus aureus and coagulase negative staphylococci were routinely tested against nine common antibiotics, inclusive of Gentamycin. Critical findings showed that the regimen used in routine primary surgery covers only 67% of staphylococcus infections (cefuroxine and Gentamycin); combinations that showed increased coverage included clindamycin and Gentamycin, and rifampicin plus Gentamycin, providing in excess of 100% coverage, and Erythromycin and Gentamycin, coverage in excess of 80%.

Discussion: Consequently we can recommend from prospective analysis of common infections at septic revision, that the antibiotic regimen at primary surgery is not sufficient to prevent infection (in isolation). Dynamic variations continuously develop in bacteria; genetic make up is regulated to optimise survival, continuously detrimentally affecting the efficacy of antibiotics against the power of super bugs, indicating a pattern in need of continuous monitoring and review.

Introduction: The triple tapered polished cemented C-stem has evolved from the study on long-term results of the Charnley design, when first fractures of the stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process. The design utilises the common engineering principle of male (stem) and female (cement) tapers engaging under load, loading the proximal femur.

Methods and Results: The C-stem was tested extensively and introduced into clinical practice in December 1993. Up to the end of October 2007, 4558 have been implanted in primary operations.

None of the 4558 stems have been revised for aseptic loosening or fracture.

The patient’s mean age at surgery was 48 years (range 15–76), and 171 hips with a mean follow-up of 11 years (range 10–13.7) have now passed 10 years. There were 97 females and 64 males in this group with 10 patients having bilateral C-stems. The main underlying pathologies were Primary Osteoarthritis 30%, Developmental Dysplasia of the hip 27% and Avascular Necrosis of the hip 19%.

Clinical outcome graded according to d’aubigne and postel for pain, function and movement has improved from 3.1, 3.1 and 2.9 to 5.9, 5.7 and 5.6 respectively.

A good quality proximal femur had been maintained in 47.1% and improved in a further 29.9%.

Discussion: The results achieved with the C-Stem design and technique are encouraging and support the concept of loading the proximal femur, but place a demand on the understanding of the technique and its execution at surgery.

Introduction: Revision arthroplasty using the impaction grafting technique is an increasingly popular technique. The lost bone stock is replaced rather than substituted with ever increasing amounts of metal. There have been many advances in the understanding of this technique in recent years. It has recently been shown that washing of the graft improves the biomechanical strength, bony ingrowth and biocompatibility of morsellised allograft bone. The aim of this study was to identify the most efficacious method of washing morsellised allograft in the operating room.

Methods: Fresh frozen femoral heads identified for research purposes were randomly divided into four groups. Group A was washed using a serial dilution technique at 37°C, group B serial dilution at 60 °C, group C pulsed lavage wash at 37°C and group D pulsed lavage wash at 60 °C. Three-gram samples of each femoral head were taken prior to washing. The heads were then washed according to the grouping. The unwashed and washed morsellised bone was then assessed for the presence of protein, haemoglobin, DNA and lipid using spectrophotometric analysis techniques. The removal of these marrow components from the femoral heads in each group was assessed as a proportion of the original content.

Results: All washing techniques removed a large proportion of the marrow load of the femoral heads. The most efficacious technique was washing by serial dilution (removal rate 67.5–87.4%). Washing by pulsed lavage removed less marrow (28.4–80.9%). Protein showed the highest removal rate (80.9–86.4%) and haemoglobin the lowest (28.4–67.5%). Removal of lipid was most affected by temperature with a larger proportion removed at 60°C as compared to 37°C.

Conclusion: We conclude that the most efficient method of washing morsellised allograft bone for impaction grafting is by serial dilution with fluid at 60°C. This information should improve the results of impaction grafting, as it is known that cleaner bone results in improved biomechanical stability, enhanced biological compatibility and accelerated bony ingrowth.

Hip arthroplasty has its true genesis in 1962 when the Charnley Total Hip was first implanted. The system comprised a stainless steel femoral stem with fixed 22,225mm head articulating against an all polyethylene acetabular cup. Both components were fixed in position with acrylic bone cement. There have been a number of changes in design, materials and surgical technique but the essential concept remains the same. The system was widely used by both senior and junior surgeons. Numerically implantations peaked at ~45,000 per annum in the late1980’s and is still at around ~25,000 per annum in the mid 2000’s. Geographically the system was used in all five continents. Patients varied widely both in age, activity, and diagnosis. It would therefore seem an appropriate vehicle to examine the variations in results of total hip replacement by patient profile, geography, and era of implantation.

A search was carried out on the US NCBI website for publications reporting on results with the Charnley system up to the end of 2002, and which comprised a follow-up of more than 10 years, and gave survivorship data. This resulted in 28 papers with 14 countries of origin available for review. For all studies basic data such as age and diagnosis, range implantation dates, likely specific design of prosthesis, origin of study and number in study was either reported or could be deduced. A ten year survivorship was reported in 16 studies for stem and cup and 7 for stem only. If the longest follow-up was considered for each study then 18 reported on stem and cup (9392 hips, implanted 1962–92) and 15 on stem only (4243 hips, implanted 1966–91). A total of 11 studies had four of more points on a survivorship curve, seven with stem and cup, four with stem only.

There are a number of points of interest in this data. The first is that with one exception the performance is remarkably consistent as shown by the survivorship curves. There is no significant difference in the survival rates from different centres, countries, and with implantation dates ranging from 1962 through to 1992. Secondly, there appears to have been little or no change in the average age of patients with implant date. There is some evidence to indicate from the 10 year data that failure rate per year is lower in older patients but does not seem to be affected by implantation date. The latter despite the fact that both surgical technique and component design changed over the 30 year implantation period. A further observation is that the failure rate per year is lower in studies with greater numbers of patients.

The general conclusion from this review is that the Charnley Total Hip is remarkably consistent in its performance both over time and location of implantation. Its performance also seems to have been affected very little by changes in technique or design.

Introduction: Freezing and storage of fresh frozen femoral heads destined for use in revision hip arthroplasty is thought to result in graft cell death. Washing of the graft following the morsellisation process also removes a large proportion of the marrow content of the allograft. However, the immunological load of the impaction allografting process remains unknown. The aim of this study was to investigate the immune response by observing any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement

Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Venous blood samples were collected pre-operatively and at set time intervals up to one year post-operatively. Using flow cytometry, analysis of venous blood allowed counts of the following cells: Helper T-lymphocytes, cytotoxic T-lymphocytes, memory T-lymphocytes, naïve T-lymphocytes, Natural Killer cells and B-lymphocytes.

Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Pre-operatively, a significant difference (p=0.03) was found between the groups of patients with respect to Natural Killer cells but other subsets showed no significant difference. Post-operatively the significant difference between Natural Killer cells resolved. T-helper lymphocytes, cytotoxic lymphocytes, memory T-lymphocytes and naïve T-lymphocytes in both groups showed decreases in values immediately post surgery, recovering to normal values within 6 weeks post-surgery. The allograft group showed significant increases from baseline in cytotoxic T-lymphocytes at 6 months (p< 0.01) and memory T-lymphocytes one year postoperatively (p=0.04). B-lymphocyte numbers did not alter significantly from baseline.

Conclusion: Cytotoxic T-lymphocytes recognise HLA-class I molecules which are present on all nucleated cells and have been implicated in having a role in osteoclast regulation. Memory T-lymphocytes are produced after a naïve T-lymphocyte is exposed to an antigen. The observed increases of these subsets were not observed in the non-grafting group suggesting the allografted bone had elicited an immunological response. At 12 months all grafts appeared radiologically stable and the immunological response may have been beneficial to the outcome.

The Triple-tapered cemented polished C-Stem has evolved from the study of long-term results of the Charnley low-frictional torque arthroplasty when the first fractured stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process- the lack or loss of proximal stem support.

The concept, design and the surgical technique cater for a limited slip of the C-stem within the cement mantle transferring the load more proximally. With a follow-up past 12 years and 4063 primary procedures there have been no revisions for aseptic stem loosening and no stem is radiologically loose.

We have reviewed 1008 primary C-Stem hip arthroplasties performed by 23 surgeons with a minimum of 5 years clinical and radiological follow-up. The mean follow-up was 7 years (range, 5 – 12) and the mean age at surgery was 57 years (range (15 – 85). In 58% the underlying pathology was primary osteoarthritis, 20% congenital dysplasia, 10% quadrantic head necrosis, 5% rheumatoid arthritis, 5% slipped upper femoral epiphysis and 4% protrusio acetabulae.

The concept of the triple tapered stem is validated radiologically with an improved proximal femoral bone stock in over 20% of cases and a maintained bone stock in 60%.

There were no post-operative complications within 1 year in 87% and no late complications (after 1 year) in 91%. The main late complications were 3.9% aseptic cup loosening, 1% infection and 0.8% dislocation. There were no aseptic loose stems.

Twenty-eight hips have been revised (2.8%), 3 for infection, 2 for dislocation and 23 for aseptic cup loosening. There were no revisions for aseptic stem loosening.

The results support the concept but place a demand on the understanding of the technique and its execution at surgery.

Impaction grafting with morsellised allograft is becoming the treatment of choice for revision arthroplasty, especially in the younger patient. The optimum treatment of the graft prior to impaction has not been determined. Some groups wash the graft prior to impaction and others do not. Washing of graft has been shown to enhance bone ingrowth in an animal model, however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing.

Paired samples of washed and unwashed morcellised FFH allograft were taken during revision hip arthroplasties. Washing was performed by 4 consecutive rinses in 300ml warmed saline, the bone being filtered between each exchange of saline. Contact cytotoxicity assays involved culture of cell lines in direct contact with bone samples. Quantitative cytotoxicity assays utilised culture media conditioned with the bone samples and subsequent assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. Assays were performed with human osteoblastic (MG63) and fibroblastic (HSF) cell lines.

Nine pairs of samples were analysed. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Quantitative assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical significance (p=0.06).

Unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.

Introduction: The long term success of impaction grafting depends on the remodelling process during incorporation. This project was designed to characterise any differences in the biochemical markers of bone turnover following revision hip arthroplasty performed with or without impaction grafting.

Methods: 87 patients undergoing revision hip arthroplasty were entered into this prospective study and grouped according to whether impaction allograft was used or not. Biochemical markers of bone turnover were assessed pre-operatively and post-operatively on day 2, day 9, week 6, 6 months and 1 year. Osteocalcin, pro-collagen type-I N-terminal propeptide and bone specific alkaline phosphatase were measured as bone formation markers. C-telopeptide, pyridinoline and deoxypyridinoline were measured as bone resorption markers.

Results: All patients had a successful radiological and clinical outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Markers of bone formation tended to rise by day 9 but the rise in osteocalcin was delayed in the graft group and was significantly lower at 6 months in comparison to the non-graft group (p=0.002). Alkaline phosphatase levels remained significantly elevated at one year in the graft group (p=0.027) whilst levels in the non-graft group had normalised. Markers of bone resorption also rise in both groups but with no significant differences between the groups.

Discussion: Following impaction grafting, new bone formation may be delayed in comparison to revisions performed without graft. The pattern of markers of bone resorption did not differ significantly between the groups suggesting that there is no large scale resorption of the impacted allograft in these cases.

These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.

Introduction: There is an increasing trend for autologous blood transfusion in hip and knee replacement and we therefore felt the need to properties of the fluid reinfused.

Objectives of the study: The study objective was to determine the volume and Haemoglobin content of the reinfused blood.

Materials and methods: We prospectively studied 108 patients with primary Hip and knee arthroplasty. The drained blood was reinfused within 6 hours as recommended by the manufacturer. The volume of the drained and reinfused fluid was measured in millilitres.. The Haemoglobin (Hb.) of the patient was measured preoperatively and postoperatively in recovery. The Hb. of the drained blood and reinfused blood were also measured.

Results : The mean volume of the drained blood in the hip replacement group was 180.6 ml. while that of the reinfused blood was 132.7 ml. The mean volume of the drained blood in the knee group was 372.78 ml. while that of the reinfused blood was 362.76 ml.

The mean Haemoglobin of the reinfused blood in the hip group was 6.9 gm/dl significantly lower (p< 0.05) than the drained blood Hb. of 10.9. Similarly the Haemoglobin of the blood reinfused in knee replacements was significantly lower at 6.8 gm/dl. (p< 0.001). This was less than half of the average Hb. content of homologous blood transfusion.

Conclusion: The Haemoglobin content of the reinfused blood in Hip and knee replacement was quite low to be considered as a replacement for homologous blood transfusion and further studies may be required to confirm the efficacy of reinfusion drainage compared to homologous blood transfusion.

Introduction: There is an increasing trend for autologous blood transfusion in hip and knee replacement and we therefore felt the need to properties of the fluid reinfused.

Objectives of the study: The study objective was to determine the volume and Haemoglobin content of the reinfused blood.

Methods: We prospectively studied 108 patients with primary Hip and knee arthroplasty. The drained blood was reinfused within 6 hours as recommended by the manufacturer. The volume of the drained and reinfused fluid was measured in millilitres.. The Haemoglobin (Hb.) of the patient was measured preoperatively and postoperatively in recovery. The Hb. of the drained blood and reinfused blood were also measured.

Results: The mean volume of the drained blood in the hip replacement group was 180.6 ml. while that of the reinfused blood was 132.7 ml. The mean volume of the drained blood in the knee group was 372.78 ml. while that of the reinfused blood was 362.76 ml.

The mean Haemoglobin of the reinfused blood in the hip group was 6.9 gm/dl significantly lower (p< 0.05) than the drained blood Hb. of 10.9. Similarly the Haemoglobin of the blood reinfused in knee replacements was significantly lower at 6.8 gm/dl. (p< 0.001). This was less than half of the average Hb. content of homologous blood transfusion

Discussion: The Haemoglobin content of the reinfused blood in Hip and knee replacement was quite low to be considered as a replacement for homologous blood transfusion and further studies may be required to confirm the efficacy of reinfusion drainage compared to homologous blood transfusion

Introduction: We performed a retrospective case control study in 80 patients who under went revision hip surgery at our unit.

Methodology: Group A (40 patients), received tranexamic acid and intra-operative cell salvage. Group B (40 patients) a matched control did not receive these treatments. Each group was divided into 4 sub groups; revision of both components, revision of components + bone grafting, revision acetabular component +/− bone grafting and revision femoral component +/− bone graft.

Results: In group A the total number of units transfused was 139 compared to 52 in group B. This represents a reduction in blood usage of 37%. The mean amount of blood transfused from cell salvage in each group was 858mls, 477mls, 228mls and 464mls. There was a significant difference in the amount of blood returned between the groups (p< 0.0001). In the control group 37 patients needed transfusion, in the study group 22 (p< 0.0001). At our unit a cost analysis calculation has shown total revenue saving of £88,000 and a potential saving throughout the trust of £316,688 per year.

Discussion: To our knowledge this is the first study to examine the use of cell salvage and tranexamic acid in revision hip surgery. Our results show that a significant reduction in blood transfusion can be made using this technique. It is vital that blood conserving strategies are developed so that future revision surgery can continue.

Fresh frozen femoral head (FFH) allograft is commonly used in impaction grafting for revision hip arthroplasty and long term success has been demonstrated by some groups. The optimum treatment of the graft prior to impaction has not yet been determined. Some groups wash the graft prior to impaction and others do not. Washing of the graft has been shown to improve bone ingrowth in a bone chamber animal model however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing.

Samples of morcellised FFH allograft were taken during revision hip arthroplasties prior to impaction grafting. Paired samples, taken before and after washing were taken from each case. Washing was performed by 4 consecutive washes in 300ml warmed saline, the bone being filtered between each exchange of saline. Cytotox-icity was assessed for all samples using both contact and extract assays. Contact assays involved culture of cell lines in direct contact with bone samples. Extract assays utilised culture media conditioned with bone samples and subsequent quantitative assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. All assays were performed using both human osteoblastic (MG63) and fibroblastic (HSF) cell lines.

Nine pairs of samples were analysed for cytotoxicity using both cell lines. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Extract assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical signifi-cance (p=0.06).

In conclusion, we have shown that unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.