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 more commonly used in the community. Antimicrobial resistance was higher when the causative organism was CNS, suggesting that multi-drug resistant CNS 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 teicoplanin 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.

Objectives: Dislocation is one of the common complications of total hip Arthroplasty. Posterolateral approach and small femoral heads have been shown to be high-risk factors for dislocation of the implanted total hip prosthesis. The use of a posterior capsulorraphy has also shown to decrease the rate of dislocation with a posterolateral approach. The objective of this study was to evaluate the early dislocation rate using size 22 mm head and a Posterolateral approach augmented with a posterior capsulorraphy.

Methods: Questionnaire and case notes review of 148 patients operated at one institution by 3 different senior surgeons from Aug’03 to Jan’05. A posterior capsulorraphy was performed in all the patients. The primary outcome measure was the dislocation of the prosthetic hip within the first year of surgery.

Results: 4 of the 148 patients (2.7%) had an episode of dislocation during the first year of surgery. 3 patients were treated conservatively and 1 required operative intervention in the form of PLAD. Radiographic analysis of this patient showed excessive anteversion of the socket(28⁰⁾.

Conclusions: Studies have consistently shown an increased rate of dislocation with a Posterolateral approach and use of a size 22mm head. A recently published study by Berry et.al has shown a 12.1% dislocation rate with the use of this approach and size 22mm head. However posterior capsulorraphy was not performed in patients in this study group. Our study shows that performing a posterior capsulorraphy can reduce early dislocation rates using Posterolateral approach and size 22 mm head. The dislocation rate (2.7%) is comparable to any other approach and the use of a larger head size.

These patients continue to be monitored to evaluate long term outcomes with this approach. (301 words)

Introduction: This study investigates whether the choose and book system satisfies the priorities of the local community and considers its implications for local elective primary lower limb arthroplasty.

Patients are offered a choice of 4 hospitals and time and date of outpatient appointment on referral from their GP practice. Research revealed that people want choice. Can popular centres still provide a service for the local population? What are the priorities of the local population when choosing a healthcare provider?

Method: A qualitative questionnaire was given to 100 people from the local community who were referred from their GP for a primary lower limb arthroplasty. This assessed patient’s opinions and priorities.

Results: 98% of patients wanted to choose their healthcare provider, 88% would not be content in any hospital other than their first choice

94% would not change hospitals if offered a shorter waiting time

Discussion: This study clearly indicates the local community want choice on referral for primary arthroplasty, but where they are operated is more important than when. The clinical quality of the provider is more important than the waiting time.

The government state patients want to choose the time and date of their first clinic appointment, however the majority of our population don’t.

The current ‘Choose and Book’ system does not fulfil patient’s priorities.

The use of rim mesh to augment acetabular defects at the time of revision hip surgery is a valuable technique. Where acetabular containment is compromised by segmental rim defects, it can be achieved by using a flexible wire mesh fixed to the wall of the ilium by multiple screws. Morsilised bone graft is then impacted onto the acetabular bed and wire mesh thus creating a new hemi-spherical acetabular bed for cementation of a new socket.

Standard AP and lateral radiographs are acceptable methods for assessing conventional socket revisions. However if a rim mesh has been used the mesh itself will obscure the socket and both columns of the acetabulum making interpretation difficult. We have modified the Judet views classically used in acetabular fracture surgery to allow better imaging of the socket. The views taken are dependant upon rim mesh position at surgery. Technique: Positioning for posterior acetabular rim mesh

From the supine position the patient is rotated 45° so that the side under examination is raised. Radiolucent pads are used to support the pelvis and leg. The hips and knees should not be flexed.

Positioning for anterior acetabular rim mesh

From the supine position the patient is rotated 45° so the non affected side is raised. Using radiolucent pads the pelvis is supported. The femur should not be flexed and externally rotated as they would be for an oblique hip

The film is centred approximately 2cm below the ASIS of the hip being examined.

These views of the hip allow complete imaging of the socket and the reconstructive construct. Radiographic evaluation of the bone graft and bone cement-graft interface can be reliably made.

We would recommend these views for the radiographic follow up of socket revisions involving the rim mesh technique.

In 1999 a statement of best practice in primary total hip replacement was approved by the Council of the British Orthopaedic Association and by the British Hip Society to provide a basis for regional and national auditable standards. We have compared practice in the North West of England to this document to ascertain adherence to this guide to best practice.

86 surgeons from 26 hospitals were included in the study. A mean of 93.3% of operations were performed in the surgeon’s usual theatre. All of these theatres had vertical laminar air flow systems. 42.2% of respondents routinely used exhaust suits. 68.1% of respondents routinely used impermeable disposable gowns, 26.1% used impermeable reusable gowns. The Charnley femoral and acetabular prostheses were the most commonly used prostheses.

All surgeons use some form of anti-thromboembolic prophylaxis. 66.2% use a combination of both mechanical and chemical means. All surgeons used antibiotic prophylaxis. The most popular choice of antibiotic was a cephalosporin. 70.7% used a three-dose regime over 24 hours. 2.6% of surgeons continued antibiotic prophylaxis for 48 hours after surgery. 93.7% of surgeons routinely use antibiotic-loaded cement.All surgeons routinely cleaned, irrigated and dried the acetabulum and femur before cement insertion. Only one surgeon did not use any form of femoral canal occlusion. 69.4% used an intramedullary bone block. Retrograde filling of the femoral shaft by means of a cement gun was practised by 65.1%.

This study has demonstrated considerable variation of practice in THA across the North West region and significant divergence from the statement of best practice approved by the BOA and BHS. The introduction of a properly funded national hip register will surely help to clarify the effect of such diverse practice on patient outcome. We would recommend that all trusts locally audit their practices and correlate them to these nationally agreed guidelines.

A secure bone/cement interface at the bone cement junction is an important requirement for the long-term success in the cemented hip arthroplasty. Cementing techniques have evolved and now involve pressurisation of the acetabulum and femur. It can be difficult to get a complete rim seal and hence adequate pressurisation due to the unique anatomy of the acetabulum and the contyloid notch.

Several acetabular pressurisers are commercially available.

We have developed an instrument for controlled and reproducible cement pressurisation in the acetabulum before socket insertion. It is a T-bar incorporating a central plunger, which protrudes from an outer sleeve when force is applied. The protrusion of the central plunger and hence the amount of force applied can be limited by a stop-sleeve.

A laboratory saw bone model was designed to assess this system and compare it with two existing pressurisers. A polypropylene model of the acetabulum was used. Included in the model were two 1.3mm diameter capillary outlets, one at its pole and one at a point close to its rim opposite the cotyloid notch. Water was free to flow through the capillaries at a pressure of 13.5” WG to represent blood flow. 5 test per pressuriser were performed.

CMW 1 Gentamicin bone cement was mixed as per manufacturers instruction in a Vacuum Mix system. The cement was then pressurised using one of three systems; the Depuy T handle pressuriser, the Exeter pressuriser and our new instrument.

The cement mantle produced with the Depuy T-handle and the Exeter pressuriser was thicker at the pole than the rim and the cement intrusion was not consistent nor reproducible. The new pressurizer produced a cement mantle equal at the pole and the rim to within 1mm. A reproducible cement mantle compatible to the shape of the socket and with cement intrusion of 5mm (+/− 1mm) could be achieved. We recommend the use of this pressuriser.

Bone cement with an antibiotic additive is currently widely available, gentamicin being the most common type. However, the high resistance of such organisms as staphylococci to gentamicin has popularised the practice of adding additional antibiotic powders to the cement mix.

This study aims to quantify the effects of adding 1g active of seven antibiotics on the viscoelastic properties of the cement from mixing to set time using a robust rheometer, developed at the University of Leeds. CMW1 Radiopaque cement was the base cement selected for its widespread familiarity.

Viscosity and elasticity were recorded at two rates of shear until the cements set. Viscosity was found to decrease with shear rate, but the cements were found to have a significant elastic component that greatly increased with shear rate. This indicates that for maximum cement penetration, maintained pressure would be more effective than “hammering”.

It should be noted that the effects described above are small compared to other theatre variables, especially temperature and humidity.

We set out to determine whether delayed opening of drains following total knee replacement reduced blood loss and hence transfusion requirements without detriment to wound status and range of movement.

We performed a prospective randomised controlled trial in two centres. Seventy six patients undergoing primary total knee replacement surgery were entered into the study. In one group (45 patients) the drains were opened immediately following surgery. In the other group (31 patients) the drains were left clamped for a period of two hours. Parameters measured following surgery were overall drainage, drop in haemoglobin, transfusion requirements, wound status and overall range of movement. All patients were followed up in a dedicated research clinic for a period of six months.

No significant difference was found in the volume of drained blood between the two groups. In addition, there was no significant difference between the pre and post operative haemoglobin levels. Range of knee movement and wound status were satisfactory in both groups.

The authors believe that although clamping drains has no adverse effects on knee wounds and range of movement, in this study it has no benefit in reducing blood loss or transfusion requirements