Diarmuid C. Molony

Anti‐biofilm activity of sub‐inhibitory povidone‐iodine concentrations against Staphylococcus epidermidis and Staphylococcus aureus

Biomaterial‐related infections continue to hamper the success of reconstructive and arthroplasty procedures in orthopaedic surgery. Staphylococci are the most common etiologic agents, with biofilm formation representing a major virulence factor. Biofilms increase bacterial resistance to antimicrobial agents and host immune responses. In staphylococci, production of polysaccharide intercellular adhesin (PIA) by the enzyme products of the icaADBC operon is the best understood mechanism of biofilm development, making the ica genes a potential target for biofilm inhibitors. In this study we report that the antibacterial agent povidone‐iodine (PI) also has anti‐biofilm activity against Staphylococcus epidermidis and Staphylococcus aureus at sub‐inhibitory concentrations (p < 0.001). Inhibition of biofilm by PI correlated with decreased transcription of the icaADBC operon, which in turn correlated with activation of the icaR transcriptional repressor in Staphylococcus epidermidis. These data reveal an additional therapeutic benefit of PI and suggest that studies to evaluate suitability of PI as biomaterial coating agent to reduce device‐related infections are merited.

A cadaveric model for suprascapular nerve injury during glenoid component screw insertion in reverse-geometry shoulder arthroplasty

BACKGROUND Reverse-geometry shoulder replacement requires fixation of a baseplate (called a metaglene) to the glenoid, to which a convex glenosphere is attached. Most systems use screws to achieve this fixation. The suprascapular nerve passes close to the glenoid and is known to be at risk of injury when devices and sutures are inserted into the glenoid. We investigate the risk posed to the suprascapular nerve by placement of metaglene fixation screws. MATERIALS AND METHODS Ten cadaveric shoulder specimens were used. A metaglene was inserted and fixed by use of 4 screws. The suprascapular nerve was dissected and its branches identified. The screw tips and their proximity to the nerve and branches were identified and recorded. RESULTS The superior and posterior screws posed the most risk to the suprascapular nerve. The nerve was engaged by the posterior screw on 4 occasions and was within 5 mm of the nerve or a branch of it in 5 others. The superior screw was extraosseous on 4 occasions, making contact with the nerve in 3 of those 4 specimens and being within 2 mm of it in the fourth specimen. CONCLUSION Metaglene fixation with screws poses a significant risk to the suprascapular nerve. Caution should be used when inserting the posterior and superior screws in particular. Short locking screws may allow adequate fixation while minimizing the risk of neurologic injury.

Hydrogen Peroxide Induced Repression of icaADBC Transcription and Biofilm Development in Staphylococcus epidermidis

Expression of the icaADBC‐encoded polysaccharide intercellular adhesion by Staphylococcus epidermidis promotes biofilm formation and represents an important virulence factor in biomaterial‐related infections following orthopedic surgery. Biofilm development by the pathogen can be viewed as a protective reaction to environmental stressors including osmotic stress, thermal stress, and antimicrobial chemotherapy. Oxidative stress, arising from the release of toxic oxygen radicals by polymorphonuclear cells, is encountered by bacteria entering the body perioperatively. Evasion of this and other cell‐mediated immune responses by pathogenic bacteria plays an important role in the development of chronic biomaterial‐related infection. Here we investigated the impact of sublethal oxidative stress induced by H2O2 (<18 mM) on S. epidermidis biofilm formation. S. epidermidis grown in brain heart infusion (BHI) media supplemented with 5 mM H2O2 or 10 mM H2O2 formed significantly less biofilm (p < 0.01 and p < 0.001, respectively) than bacteria grown in BHI alone. Consistent with this, using reverse transcription‐polymerase chain reaction expression of the ica locus was also shown to be reduced by subinhibitory concentrations of H2O2. Furthermore, diminished ica operon expression correlated with increased expression of icaR, which encodes a repressor of icaADBC. Thus, these data suggest that mild oxidative stress downregulates biofilm development by S. epidermidis and may have potential in a therapeutic context.

Attitudes of the medical profession to whole body and organ donation

Cadaveric dissection remains an important part of undergraduate medical education in anatomy. In a concerted effort to rise the number of doctors in practice in Ireland the amount of medical school placements has been increased steadily since 1995. This poses a problem as the number of cadavers has remained unchanged despite an overall increase in the population Ireland over the last twenty years. The medical profession plays a central part in raising public awareness of living and post-mortem organ donation. Previous studies have examined the attitudes of medical students to whole body donation, however to our knowledge this is the first study that evaluates the attitudes of medical professionals. We assess the opinions of junior and senior doctors at the time of their dissection experience and in their current practice. We show that their attitudes have changed as their clinical experience grows.

Radial head replacement with pyrocarbon prosthesis: early clinical results

Comminuted radial head fractures are challenging to treat with open reduction and internal fixation. Radial head arthroplasty is a favourable technique for the treatment of complex radial head fractures. The purpose of this study was to evaluate the functional and radiological outcomes of radial head arthroplasty using modular pyrocarbon radial head prosthesis.

Less invasive innominate osteotomy.

In 1961, Salter described the innominate osteotomy for the treatment of dysplastic acetabulum in children presenting late with developmental dysplasia of the hip. He recommended the Gigli saw as the safest instrument for the osteotomy cut and his postoperative immobilization was with a hip spica cast. These have been the standard practice. However, an extensive exposure is required to facilitate passage of the Gigli saw under the sciatic notch while the application of a hip spica can be difficult and prolongs anaesthetic time. We describe a less invasive technique using an oscillating saw for the osteotomy cut. This allows for minimal exposure hence short operation time and quick recovery. We use an abduction brace for our postoperative immobilization thereby significantly reducing anaesthetic time. Fifty innominate osteotomies performed in 49 patients using this technique were reviewed retrospectively. There were 46 female and three male patients. The senior author performed all surgeries. The average age at surgery was 24 months (18–54) and the mean follow-up period was 25 months (12–60). The mean preoperative acetabular index was 35.1°, whereas the acetabular index at final follow-up was 14.9° (P<0.0001). Average duration of surgery was 25 min with minimal blood loss (less than 50 ml). All went home by the second postoperative day. There was no intraoperative complication. Two patients had minor superficial wound infections that resolved uneventfully. There was no loss of correction. We suggest that the oscillating saw is a safe instrument for performing an innominate osteotomy, it allows for less invasive surgery hence less morbidity and quicker recovery without compromising the surgical outcome. The abduction brace can be used for immobilization after innominate osteotomy without loss of correction.

Traumatic Floating Clavicle- A case report.

Introduction: Shoulder injuries after high velocity trauma are common. Clavicle is affected in almost half of these cases. Even so, bipolar dislocation of the clavicle is an unusual injury and seldom reported in the literature. Conservative management is used for almost all the cases and only selected cases will undergo surgical treatment. Case Report: A 52 year old right electrician presented to the emergency department following a fall from a push bicycle. Plain radiographs identified a left first metacarpal (MC) fracture and a bipolar fracture of his right clavicle. Following Fracture Clinic review, significant deformity of the medial clavicle was noted and a CT scan showed anterior dislocation of the medial fragment. Given the degree of deformity and this functional requirement we felt that operative treatment was most appropriate for his unstable medial clavicle fracture dislocation. Conclusion: Surgical treatment of floating clavicle has an important role in the management of fit and active patients. It is important to identify the mechanism of injury and deforming forces in fractures and only after this to plan to neutralise these where appropriate.

Free-hand versus novel specialised jig guidance for the passing of intramedullary wires in olecranon fracture fixation: A comparative study

The treatment of olecranon fractures frequently involves the use of tension-band fixation. Although associated with high union rates, this method has a high incidence of morbidity associated with soft tissue compromise and limitation of range of movement requiring frequent re-operation for removal of metal. We describe the use of a simple jig to ensure intramedullary placement of longitudinal K-wires and compare the accuracy of placement of Kirschner (K)-wires using this device with the traditional free-hand method. We found the distance from the centre of the medullary canal, the range and standard deviations of K-wire positions to be significantly more precise when the jig was used. This has applications for the use of the device, both with standard metallic radio-opaque wires and potentially with bio-absorbable pins.