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 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.

Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, biofilms were challenged by a low-intensity ultrasound (1.5MHz, 30mW/cm2, pulse duration 200µs/1KHz) for 20 minutes and gentamicin. 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. Further studies confirmed that the mechanism of action was due to incomplete disruption of the extracellular matrix with subsequent metabolic stimulation of the dormant biofilm-associated bacteria due to increased nutrient availability and oxygen tension.

Low intensity pulsed ultrasound was associated with a 4-fold reduction in the effective biofilm eradication concentration of gentamicin; bringing the MBEC of gentamicin to within clinically achievable concentrations.

Aim

The aim of this study was to determine whether the absence of periosteal reaction on plain radiographs was predictive of exchange nail failure in lower limb diaphyseal fracture non-unions.

Nasal carriers of methicillin sensitive Staphylococcus aureus (MSSA) have an increased risk for health-care associated infections. There is currently no national screening policy for the detection of MSSA in the UK. This study aimed to: evaluate the diagnostic performance of molecular and culture techniques in MSSA screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on MSSA detection in orthopaedic patients. Paired nasal swabs for PCR assay and culture of S. aureus were collected from a study population of 273 orthopaedic outpatients due to undergo joint replacement surgery.

The prevalence of MSSA nasal colonisation was found to be between 22.4–35.6%. The current standard direct culturing methods for detecting S. aureus significantly underestimated the prevalence (p=0.005), failing to identify its presence in ∼1/3 of patients undergoing joint replacement surgery.

Modelling these results to national surveillance data, it was estimated that 800–1200 MSSA surgical site infections could be prevented annually in the UK by using alternative diagnostic methods to direct culture in pre-operative MSSA screening and eradication programmes.

The aim of this study was to identify risk factors for failure of exchange nailing for femoral diaphyseal fracture non-unions. The study cohort comprised 40 patients with femoral diaphyseal non-unions treated by exchange nailing. The main outcome measures were union, number of secondary fixation procedures required to achieve union and time to union. Univariate analysis and multiple regression were used to identify risk factors for failure to achieve union.

The mean age of the patients at exchange nail surgery was 37 years. The median time to exchange nailing from primary fixation was 8.4 months. Multiple causes for non-union were found in 14 (35.0%) cases, with infection present in 12 (30.0%) patients. Further exchange procedures were required in nine (22.5%) cases, one patient (2.5%) required the use of another fixation modality, to achieve union. Union was ultimately achieved in 35 (94.5%) patients. The median time to union was 9.4 months after the exchange nail procedure. Univariate analysis confirmed that cigarette smoking and infection were predictive of failure (p<0.05). Multi-regression analysis found that Gustilo-Anderson grade, presence of dead bone or a gap and infection were predictive of exchange nail failure (p <0.05).

Exchange nailing is an effective treatment for aseptic femoral diaphyseal fracture non-union. Patients with infection required more than one procedure. Smoking, infection and the presence of dead-bone or a gap at the fracture site were associated with an increased risk of further fixation surgery.

The aim of this study was to identify risk factors for failure of exchange nailing in tibial diaphyseal fracture non-unions. The cohort comprised 99 tibial diaphyseal fracture non-unions treated by exchange nailing. The mean age of the patients at exchange nail surgery was 36 years. The median time from primary fixation to exchange nailing was 6.4 months. The main outcome measures were union, number of secondary fixation procedures required to achieve union and time to union. Univariate analysis and multiple regression were used to identify risk factors for failure to achieve union.

Multiple causes for non-union were found in 31.3% cases, with infection present in 32.3%. Further exchange procedures were required in 35.4%, 7.1% required the use of other fixation modalities. Union was ultimately achieved in 97.8%. The median time to union was 8.7 months. Univariate analysis revealed that cigarette smoking, an atrophic pattern of non-union and infection were predictive for failure of exchange nailing (p<0.05). Multi-regression analysis found that only infection was statistically significantly predictive (p<0.05) of exchange nail failure.

Exchange nailing is an effective treatment for tibial diaphyseal non-unions even in the presence of infection. Smoking, atrophic pattern of non-union and infection are associated with an increased risk of further fixation surgery.

Proximal femoral fractures remain the most common reason for admission to hospital following orthopaedic injury, with an annual cost of £1.7 billion to the National Health Service and social care services. Fragility fractures of the hip in the elderly are a substantial cause of mortality and morbidity. Revision surgery for any cause carries a higher morbidity, mortality, healthcare- and social economic burden. Which patients suffer failed surgery and the reasons for failure have not been established. The aim of this study was to determine which patients are at risk of failed proximal femoral fracture surgery, the mechanism and cause fo failed surgery and modifiable patient factors associated with failure of hip fracture surgery.

From prospectively collected data of 795 consecutive proximal femoral fractures admitted between July 2007 and July 2008, all peri-operative and post-operative complications were identified.

55 (6.9%) patients were found to have developed a surgical complication requiring further intervention. Risk factors included younger age (p=0.01), smoking (p=0.01) and cannulated screw fixation (p<0.01). Cannulated screw fixation was associated with a 30.9% complication rate. Mechanical cause was the most common reason for cannulated screw failure. Hip hemiarthroplasty most commonly failed by infective causes. Inter-trochanteric and subtrochanteric fracture fixation had very low failure rates. Surgical complication was not found to be associated with an increased mortality but a post-operative medical complication (21.8%) was associated with higher rate of mortality at 4-years (78.5%) and shorter time to mortality. (Median time 0.16 years (95% CI 0.00–0.33).