Gram-negative organisms are increasingly seen as causative pathogens in orthopaedic fracture surgery, which might necessitate a change in antibiotic prophylaxis protocols.

A single-centre retrospective review of antibiogram results from all patients treated for fracture-related infection (FRI) was conducted. Subgroup analysis was undertaken to identify any host, injury or treatment variables predisposed to Gram-negative infection.

The bacteriological results of 267 patients who underwent surgical treatment for FRI were analysed. Pathogens were isolated in 216 cases (81%), of which 118 (55%) were Gram-negative infections. Fractures involving the tibia and femur (p=0.007), the presence of soft tissue defect (p=0.003) and bone defects (p=0.001) were associated with an increased risk of developing a Gram- negative FRI.

Gram-negative fracture-related infections were associated with injuries experiencing bone loss and those requiring soft tissue reconstruction. It is, therefore, prudent to consider extended Gram-negative directed antimicrobial prophylaxis in these cases to prevent the development of fracture-related infection

The Cierny and Mader classification assists with decision-making in the management of osteomyelitis by strafying the host status and the pathoanatomy of disease. However the anatomical type IV represents a heterogenous group with regards to treatment requirements and outcomes. We propose that modification of the Cierny and Mader anatomical classification with an additional type V classifier (diffuse corticomedullary involvement with an associated critical bone defect) will allow more accurate stratification of patients and tailoring of treatment strategies.

A retrospective review of 83 patients undergoing treatment for Cierny and Mader anatomical type IV osteomyelitis of the appendicular skeleton at a single centre was performed.

Risk factors for the presence of a critical bone defect were female patients (OR 3.1 (95% CI 1.08– 8.92)) and requirement for soft tissue reconstruction (OR 3.35 (95% CI 1.35–8.31)); osteomyelitis of the femur was negatively associated with the presence of a critical bone defect (OR 0.13 (95% CI 0.03–0.66)). There was no statistical significant risk of adverse outcomes (failure to eradicate infection or achieve bone union) associated with the presence of a critical-sized bone defect. The median time to bone union was ten months (95% CI 7.9–12.1 months). There was a statistically significant difference in the median time to bone union between cases with a critical bone defect (12.0 months (95% 10.2–13.7 months)) and those without (6.0 months (95% CI 4.8–7.1 months))

This study provided evidence to support the introduction of a new subgroup of the Cierny and Mader anatomical classification (Type V). Using a standardised approach to management, comparable early outcomes can be achieved in patients with Cierny and Mader anatomical type V osteomyelitis.

However, to achieve a successful outcome, there is a requirement for additional bone and soft tissue reconstruction procedures with an associated increase in treatment time.

Abstract

Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, with cumulative treatment costs for all prosthetic joint infections estimated to be ∼ $1 billion per annum (UK and North America). Its ability to develop resistance or tolerance to a diverse range of antimicrobial compounds, threatens to halt routine elective implant surgery. One strategy to overcome this problem is to look beyond traditional antimicrobial drug therapies and investigate other treatment modalities. Biophysical modalities, such as ultrasound, are poorly explored, but preliminary work has shown potential benefit, especially when combined with existing antibiotics. Low intensity pulsed ultrasound is already licensed for clinical use in fracture management and thus could be translated quickly into a clinical treatment

Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, biofilms were challenged with gentamicin +/− low-intensity ultrasound (1.5MHz, 30mW/cm2, pulse duration 200µs/1KHz) for 180 minutes and 20 minutes, respectively. The primary outcome measures were colony-forming units/mL (CFU/mL) and the minimum biofilm eradication concentration (MBEC) of gentamicin. The mean number of S. aureus within control biofilms was 1.04 × 109 CFU/mL. Assessment of cellular metabolism was conducted using a liquid-chromatography-mass spectrometry, as well as a triphenyltetrazolium chloride assay coupled with spectrophotometry.

There was no clinically or statistically significant (p=0.531) reduction in viable S. aureus following ultrasound therapy alone. The MBEC of gentamicin for this S. aureus strain was 256 mg/L. The MBEC of gentamicin with the addition of ultrasound was reduced to 64mg/L. Metabolic activity of biofilm-associated S. aureus was increased by 25% following ultrasound therapy (p < 0 .0001), with identification of key biosynthetic pathways activated by non-lethal dispersal.

Low intensity pulsed ultrasound was associated with a four-fold reduction in the effective biofilm eradication concentration of gentamicin, bringing the MBEC of gentamicin to within clinically achievable concentrations. The mechanism of action was due to partial disruption of the extracellular matrix which led to an increase of nutrient availability and oxygen tension within the biofilm. This metabolic stimulus was responsible for the reversal of gentamicin tolerance in the biofilm-associated S. aureus.

Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, costing the NHS £120–200 million per annum. Its ability to develop tolerance to a diverse range of antimicrobial compounds, threatens to halt routine elective implant surgery. One strategy to overcome this problem is to look beyond traditional antimicrobial drug therapies and investigate other treatment modalities. Biophysical modalities, such as ultrasound, are poorly explores, but preliminary work has shown potential benefit, especially when combined with existing antibiotics.

Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, bacterial biofilms were challenged by gentamicin +/− low-intensity ultrasound (1.5MHz, 30W/cm2, pulse duration 200µs/1KHz) for 20 minutes. The outcome measures were colony-forming units/mL (CFU/mL) and the minimum biofilm eradication concentration (MBEC) of gentamicin.

The mean number of S. aureus within control biofilms was 1.04 × 109 CFU/mL. There was no clinically or statistically significant (p=0.531) reduction in viable S. aureus following ultrasound therapy alone. The MBEC of gentamicin for this S. aureus strain was 256 mg/L. The MBEC of gentamicin with the addition of ultrasound was 64mg/L.

Low intensity pulsed ultrasound was associated with a four-fold reduction in the effective biofilm eradication concentration of gentamicin; bringing the MBEC of gentamicin to within clinically achievable concentrations

Introduction

Carriers of Staphylococcus aureus, both methicillin sensitive (MSSA) and methicillin resistant (MRSA), have an increased risk for health-care associated infections. Despite WHO recommendations there is currently no national screening and eradication policy for the detection of MSSA in the UK or USA. This study aimed to evaluate the effectiveness of current standard MRSA eradication therapies in the context of S. aureus decolonisation prior to joint replacement surgery.

Objectives

A successful outcome following treatment of nonunion requires the correct identification of all of the underlying cause(s) and addressing them appropriately. The aim of this study was to assess the distribution and frequency of causative factors in a consecutive cohort of nonunion patients in order to optimise the management strategy for individual patients presenting with nonunion.

Introduction

Fracture non-union is a devastating cause of patient morbidity. The cost of NU treatment ranges from £7,000 to £79,000. With an estimated 11,700 cases in the UK pa the financial implications are huge, potentially costing several hundreds of million of pounds annually.

Successful outcome in the management of non-union is based upon correctly identifying the underlying cause(s) and addressing them appropriately.

Introduction: Despite advances in surgical and anaesthetic techniques the mortality after hip fracture has not significantly changed in the last 40 years. Pre-operative anaemia is a risk factor for peri-operative death.

We speculate that a significant proportion of the blood loss related to hip fracture has occurred prior to surgery. Identifying patients at risk of pre-operative anaemia can facilitate appropriate medical optimisation. This study is unique in its attempt to quantify the blood loss associated with the initial hip injury.

Methods: In a retrospective study over 12 months all patients with both a diagnosis of hip fracture and an operative delay of > 48 hours were assessed. The information collected included: fracture classification, serial haemoglobins and patient comorbidities. The exclusion criteria included a pre-injury diagnosis of anaemia and gastrointestinal bleeds.

Results: 68 intracapsular and 50 extracapsular hip fracture patients had serial haemoglobins and operative delays of > 48hrs (mean 75hrs, range 48–270hrs).

The mean lowest recorded haemoglobin prior to surgery for both extracapsular and intracapsular fractures were 95.0 g/L (+/−SEM 2.2) and 108.5 g/L (+/−SEM 2.2) respectively. The difference was statistically significant (Students t-test p< 0.05).

The mean haemoglobin drop for male and female patients with extracapsular hip fractures were 15.0 g/l (range 0–40 g/l) and 19.3 g/l (range 0–49 g/l) respectively and the mean haemoglobin drop for male and female intracapsular fracture patients were 10.2 (range 0–59 g/l) and 10.5 g/l (range 0–41 g/l) respectively.

Conclusions:

Hip fracture patients have a large drop in haemoglobin that is likely to be associated with the initial trauma. Patients with extracapsular fractures demonstrate a greater haemoglobin loss than those with intracapsular fractures. This highlights the need for anaesthetic and orthopaedic staff to be vigilant to the risk of pre-operative anaemia in this cohort of frail patients.