Aims

We aim to objectively assess the impact of COVID-19 on mean total operative cases for all indicative procedures (as outlined by the Joint Committee on Surgical Training (JCST)) experienced by orthopaedic trainees in the deanery of the Republic of Ireland. Subjective experiences were reported for each trainee using questionnaires.

Knee osteoarthritis is a common, debilitating condition. Intra articular corticosteroid injections are a commonly used non-operative treatment strategy. Intra articular hip injection with Ketorolac (an NSAID) has proven to be as efficacious as corticosteroids. No prior study compares the efficacy of Ketorolac relative to corticosteroids for relief of discomfort in knee osteoarthritis. The study design was a single centre double blinded RCT. Severity of osteoarthritic changes were graded on plain film weightbearing radiographs using the Kellgren and Lawrence system. Injection was with either 30mg Ketorolac or 40mg Methylprednisolone, given by intra-articular injection, in a syringe with 5mls 0.5% Marcaine. Pre-injection clinical outcomes were assessed using the Numerical Pain Score (NPS), WOMAC, and Oxford knee scores. Patients' NPS scores were assessed at Day 1 and Day 14 post-injection. An assessment of all clinical outcomes took place in clinic at six weeks. There were 72 participants (83 knees) in the study. No patients were lost to follow-up. Mean age was 62.66 years (Range 29–85). 42 knees received a corticosteroid injection, 41 a NSAID injection. Mean Kellgren and Lawrence score was 3.1. There was no significant difference in pre-injection clinical scores in either group. There was a significant improvement of NPS on Day 1 and 14 in both injection groups(p<0.05). These improved pain scores were sustained at 6 weeks in both groups. WOMAC and Oxford Knee Scores showed a statistically significant improvement in the corticosteroid group. WOMAC scores showed significant improvement in the NSAID group, however these improvements didn't achieve statistical significance using the Oxford Knee Score. Corticosteroid or NSAID injectate are a safe and effective non-operative treatment strategy in the patient with knee osteoarthritis. Ketorolac appears to provide effective medium-term improvement of pain and clinical scores. Further follow-up is recommended to investigate if this trend in sustained.

Introduction

Surgical gloves function as a mechanical barrier that reduces transmission of body fluids and pathogens from hospital personnel to patients and vice versa. The effectiveness of this barrier is dependent upon the integrity of the glove. Infectious agents have been shown to pass through unnoticed glove microperforations which have been correlated to the duration of wear. Varying factors may influence the integrity of the glove such as the material, duration of use, activities and fit. Studies have recommended changing gloves 90 minutes into a general surgical operation, however there are no known EBM recommendations in orthopaedic surgery.

Introduction

Tourniquets have been used for many years during total knee arthroplasty as a means of achieving a bloodless field for better visualization and cement-bond inter-digitation. Controversy has surrounded the necessity for a tourniquet in past years. There are many advantages and disadvantages to using a tourniquet, and one prominent disadvantage is a purported increase in post-operative pain and limitations in range of motion.

Introduction

The role of diathermy in orthopaedic surgical practice has increased since its introduction. It is widely used for underlying tissue dissection, cutting, and haemostasis. Previous studies have compared electrosurgical and scalpel incisions in terms of wound infection, wound-related pain, and blood loss. There are well documented hazards associated with diathermy use including burns injury, electrocution, hypoxic stress, inhalation of diathermy plume, and gene mutation. No single study to date has focused on the potential for diathermy tips to cause wound contamination and infection. We sought to identify whether diathermy tips could be possible sources of infection in orthopaedic procedures.

The role of diathermy in orthopaedic surgical practice has increased since its introduction. It is widely used for underlying tissue dissection, cutting, and haemostasis. Previous studies have compared electrosurgical and scalpel incisions in terms of wound infection, wound-related pain, and blood loss. There are well documented hazards associated with diathermy use including burns injury, electrocution, hypoxic stress, inhalation of diathermy plume, and gene mutation. No single study to date has focused on the potential for diathermy tips to cause wound contamination and infection. We sought to identify whether diathermy tips could be possible sources of infection in orthopaedic procedures.

To determine the prevalence of bacterial contamination of diathermy tips during orthopaedic surgery and to assess any correlation with surgical site infections.

From July 2013 to September 2013, the diathermy tips from 86 consecutive orthopaedic procedures using diathermy were cultured using direct and enriched media. None of the diathermy tips were used for the skin incision. All patients underwent an orthopaedic procedure for a non-infected condition. For each procedure an unused control diathermy tip was placed on the instrument table at the beginning of the procedure and processed similarly. All patients were followed for any postoperative complications.

108 diathermy tips from 86 orthopaedic procedures were cultured. None of the tips cultured directly on blood agar demonstrated bacterial growth. Following enrichment culture, 6 (5.6%) of the procedure diathermy tips and 1 (0.92%) of the control tips demonstrated bacterial growth. Coagulase-negative staphylococci (83.3%) and proprionibacterium (16.7%) were cultured from the tips. 1 of the patients who had bacterial growth from the diathermy tip developed a superficial surgical site infection.

Surgical site infections contribute substantially to orthopaedic surgical morbidity and mortality each year. The prevention of these infections encompasses careful operative technique, preoperative antibiotics, and a number of important measures to minimize the risk of bacterial contamination posed by operative staff, the operating theatre environment, and the patient's endogenous skin flora. Identifying potential bacterial sources is an important component of surgery. The two bacteria cultured in our study (coagulase-negative staphylococci and proprionibacterium) are both well known major culprits in orthopaedic infections, responsible for up to 70% of early and late peri-prosthetic infections. Our study suggests diathermy tips and the tissue coagulated by its use may not be as sterile as previously thought. There may be benefit in changing the diathermy tips during orthopaedic procedures as they may represent a possible source of bacterial contamination.

An interesting case with excellent accompanying images, highlighting the significance of tourniquets in controlling exsanguination, whilst also raising the issue of amputation versus reconstruction in severely injured limbs.

A 39 year old male motorcyclist was BIBA to the Midland Regional Hospital in Tullamore, following a head-on collision with a bus at high velocity. On arrival, he was assessed via ATLS guidelines; A- intubated, B- respiratory rate 32, C - heart rate 140bpm, blood-pressure 55/15 and D- GCS 7/15. Injuries included partial traumatic amputation of the right lower limb with clearly visible posterior femoral condyles, a heavily comminuted distal tibial fracture and almost complete avulsion of the skin and fat at the popliteal fossa. Obvious massive blood loss at the scene had been tempered by a passer-by who applied a beach towel as a makeshift tourniquet. CT Brain demonstrated extra-dural and subarachnoid haemorrhages with gross midline shift. Unfortunately, the neurosurgical team in Beaumont concluded that surgical intervention would be inappropriate. However, his kidneys had not sustained ATN and were made available for donation.

Two vital surgical issues were featured in this case. Firstly, it highlighted the importance of tourniquets in controlling exsanguination in a trauma situation¹. Secondly, it raised the critical issue of amputation versus reconstruction in severely injured limbs^2,3.

Without prompt placement of a make-shift tourniquet by a passer-by, this patient would have almost certainly died at the scene of the accident. Two kidneys were successfully donated as a result.

The importance of appropriate tourniquet use cannot be overstated. This case highlights its potential life or limb-saving capabilities in emergency trauma situations. It also raises the critical issue of amputation versus reconstruction in acute emergency situations.

Introduction: There is little epidemiological data on childhood injury in Ireland, despite large numbers of referrals to fracture clinics particularly in the summer months. Information is difficult to obtain retrospectively, and our aim was to quantify paediatric injury referrals to our clinics and analyse trends in injury patterns.

Methods: A prospective injury surveillance system was initiated in our department. Parents were asked to record demographic information and a brief description of the injury at fracture clinics or admission to the ward. Diagnosis and treatment was completed by the attending doctor. Details were transferred to a customised database for analysis.

Results: Overall compliance was excellent. Of 397 recorded referrals, 66% had confirmed fractures, and 20% of these were admitted for operative management. There was an equal sex distribution, and mean age at presentation was 9.1 years. The peak hour of injury was 7 – 8 pm, with fairly even distribution throughout the week. 62% of injuries were due to falls. 39% of injuries occured in or about the home, including 61% of all falls greater than 1 metre, most often from walls and slides. Other common locations for injury were school (16%) and sportsfields (14%). Gaelic football and soccer were the predominant sports causing injury. Fractures occuring during unsupervised sport were more likely to need surgery. Road traffic accidents were an uncommon cause of injury. Home ‘bouncy castles’ and trampolines were a notable cause of injury, causing 6% of all fractures, particularly of the upper limb. Predictably, 41% of all fractures involved the radius. Fractures of the distal humerus, diaphyses of radius, ulna and tibia were most likely to need operative management.

Discussion Analysis yielded a timely insight into the local epidemiology of childhood injuries. In comparison with other studies, sports related injuries were frequent and road accidents were unusually few in our group. Many injuries occurring late in the evening needed early reduction, with almost two thirds of surgical procedures performed out of hours with significant implications on theatre and radiology staffing. A large proportion of higher energy trauma occured in or about the home, representing a potential area for injury prevention stratgies.

Heterotopic ossification (HO) is a common complication following total hip replacement with a number of papers reporting an incidence of greater than 40%. In an effort to reduce the degree of contamination of the abductor muscle bed with osteoprogenitor cells, we used a plastic protective shield during the preparation and reaming of the femoral head in the hope that this would result in a decreased incidence of HO.

One hundred and forty consecutive metal-on-metal resurfacing procedures (mean age 52.3 years) utilizing the Birmingham hip prosthesis were performed between March 1999 and May 2002. Pre-operative diagnosis included osteoarthritis (105), Dysplasia (19), AVN (8), Inflammatory arthropathy (8). In the first 70 cases wet swabs packed around the femoral head were used in an attempt to reduce bone contamination. For all subsequent cases, bone contamination was controlled by the use of the plastic shield. Patients were reviewed clinically and radiologically at a mean of 36.1 (range 24–62) months post operatively. Pre-operative and follow up radiographs were assessed for presence of HO according to the Brooker classification. Harris hip and UCLA activity scores were recorded pre- and post-operatively on all patients. Three patients were lost to follow up.

Eighteen patients (12.9%) were noted to have HO on follow up radiographs. Sixteen patients in the initial group when no shield was used developed HO (Brooker I [10], II [2] & III [1]). Only two patients developed HO (Brooker I) following introduction of the protective shield. This modification in surgical technique was statistically significant in decreasing incidence of HO. All patients with radiological abnormalities were asymptomatic. We propose that this protective shield should be used during resurfacing hip arthroplasty as prophylaxis against ectopic new bone formation.

Introduction: Staphylococcal bacteria, especially the coagulase negative Staphylococci, are responsible for the majority of orthopaedic device related infection. These infections are sub acute, and may not present for months or years following surgery. The virulence of these bacteria is related to their ability to form biofilm, a protective slime which allows them to survive the effects of the host immune system and antimicrobial therapy. Treatment of biofilm based infection almost always necessitates removal of the implant.

Recent work has identified environmental stimuli which induce biofilm formation in Staphylococci. These include stressors such as high temperature, high osmolarity, anaerobiosis, nutrient depletion, salt, ethanol and subinhibitory concentrations of certain antimicrobial drugs. Given the ability of these bacteria to survive the “respiratory burst” from the cells of the mononuclear-macrophage system, we hypothesised that oxidative stress may be one such promoter of biofilm formation by Staphylococci.

Methods and Materials: Staphylococcus epidermidis CSF41498 and Staphylococcus aureus RN422O were selected for study as these are known biofilm forming organisms. Hydrogen peroxide (H₂O₂) was used as an oxidizing agent.

Bacteria were incubated for 24 hours at 37°C in Brain-Heart Infusion (BHI, Oxoid) containing progressively weaker concentrations of H₂O₂ to determine a Minimal Inhibitory Concentration (M.I.C.) for the representative strains. Bacterial viability was assessed by measuring the optical density of the incubated culture using a cell density meter (Ultraspec 10, Amersham Biosciences).

The bacteria were then grown as a biofilm on a 96 well microtitre plate (Nunc) in the presence of subinhibitory concentrations of H₂O₂, using pure BHI as a control. Semiquantative determination of biofilm formation was performed by washing the plates, staining the adherent cells with crystal violet, and measuring the light absorbance of the adherent stained cells at 492 nm using a Multiskan plate reader (Flow Laboratories).

Results: The M.I.C. of H₂O₂ was 18 mM for both Staphylococcus epidermidis CSF41498 and Staphylococcus aureus RN422O. Concentrations of H₂O₂ of 16 mM and below had no normal bacterial growth and replication.

There was no difference in biofilm formation by Staphylococcus epidermidis csf41498 in the presence of 15 mM H₂O₂ when compared to that of the control. However, H₂O₂ had a significant inhibitory effect on biofilm formation by Staphylococcus aureus RN422O, even at a concentration well below the M.I.C.

Conclusion: We conclude that oxidative stress may have an antibiofilm action on certain Staphylococcal species, which is independent from its bactericidal effect, and which is manifest at a concentration below the M.I.C. for that species.

MRSA wound infection following Total joint arthroplasty is catastrophic with disastrous consequences. Our aim was to determine the prevalence and risk factors for MRSA colonization in patients presenting for orthopaedic surgery in our unit. All patients admitted to the hospital for elective arthroplasty over a four year period were included in the study. At the time of admission, a detailed questionnaire was completed by each patient. Routine nasal, throat, axilla, perineum swabs and from any pre-existing wound sites were sent for culture.

Among 2900 patients studied, 42 patients (1.4%) were positive for MRSA on admission. The prevalence of MRSA colonization in patients who were admitted directly from Nursing homes or from own home was 36.7% and 1.3% respectively. All MRSA positive patients who were admitted directly from home had at least one documented hospital admission in the preceding year and/or antibiotic administration within three months prior to admission. The risk factors identified for MRSA colonization were in risk order : Nursing home residency(p< 0.05), previous hospital admission(p< 0.05), antibiotic administration in previous three months(p< 0.05), and female gender(p< 0.01 )Statistical analysis with Chi squared test for independence p< 0.05 considered significant.

Present MRSA screening focuses on all patients being admitted for surgery, this contrasts to North American policies of screening only patients with risk factors. We would question the validity and economical reasoning of general rather than targeted screening procedures.

There is little data regarding the epidemiology of childhood injury in Ireland. This is difficult to obtain retrospectively. The aim of this study was to prospectively evaluate paediatric trauma referrals to our department, describe their epidemiology, and identify potentially preventable injuries in children. Our unit at the National Childrens Hospital is located in a growing suburban area in South Dublin. Injury surveillance was conducted on orthopaedic referrals by distributing a form to parents of children attending fracture clinics or admitted acutely for surgery. Parents were asked for demographic information, and a brief description of the injury in terms of location, mechanism and circumstance of injury. Diagnosis was completed by the attending doctor and data was transferred to a computerised database. We analyzed data from the 397 referrals in the first month of this study. The mean age of injury was 9.1 years and the male: female ratio was 1.3:1. The peak hour of injury was 7 – 8 pm. Only 33% of injuries occured during the weekend. 62% of injuries were due to falls, usually form the standing position. The most common location for injury was in or about the home (39%), and other notable locations were school (16%) and sportsfield (14%). 61% of falls greater than 1 metre occurred at home, mostly from walls and childrens slides. 20% of injuries occurred while participating in organized sport, including Gaelic football, soccer and hurling. Injuries occuring during unsupervised sport were more likely to need surgery. Domestic ‘bouncing castles’ and trampolines, increasingly popular in our area, were a notable cause of significant trauma to the upper limb. 7% of injuries occurred by falling from a bicycle, but vehicular road traffic accident was an uncommon cause of injury. 263 children had confirmed fractures, other injuries consisting largely of sprains to the ankle, elbow and wrist. Predictably, the bones most commonly fractured were the radius (41%), phalanges (15%) and humerus (11%). 20% of fractures needed operative management, mostly forearm manipulation under anaesthesia. 63% of operative cases were performed outside of normal working hours. Several countries utilise injury surveillance as a means of development and evaluation of injury prevention strategies. In our initial study, basic surveillance has outlined local characteristics of chilhood trauma, and some trends were noted. In particular, we suggest home injuries need further attention in out catchment area.

Currently, data on the complication rates of primary total hip arthroplasty (THA) in Ireland is not available. We surveyed all consultant members of the Irish Orthopaedic Association (IOA) to determine the self reported complication rates of primary THA and analysed national audit data from the Economic and Social Research Institute (ESRI) for 2002. We received an 83% response rate to our survey. 58 surgeons reported data on 5,424 primary THAs for the year 2003. The mean dislocation rate was 1.02% and those using a posterior approach reported a significantly higher dislocation rate (p< 0.05). Deep infection rates were 0.44% and 29% of these were MRSA infections. There was no significant benefit reported from the use of body exhaust operative attire. The mean rate of venous thrombo-embolism (VTE) was 3.5%. There was no statistical difference reported in VTE rates when prophylaxis was commenced pre or post operatively, neither was there any significant benefit reported from using VTE prophylaxis for an extended period beyond the length of inpatient stay, nor from patients wearing graduated compression elastic stockings. ESRI national audit rates for dislocation were 25.7%, and rates of deep infection and VTE were 0.87% and < 0.1% respectively in 2002. Deficiencies in available ESRI data and questionable reliability of self reported rates, underline the necessity for a national Hip Register database in Ireland. The accurate recording of objective data on primary THA could provide an evidence base to improve surgical THA practices and patient outcomes and provide significant healthcare savings.

The number of skate related injuries has seen a resurgence in the western world with almost 51000 patients in 1999 presenting to US hospitals with a skateboard related injury, almost 90% of these being male and almost 70% of these are orthopaedic related injuries. Protection , particularly wrist guards, elbow pads, knee pads and recognized helmets are all necessary in protecting the young child against orthopaedic injuries. However despite these physical barriers little training or supervision exists in adequately educating children as to the dangers of these devices. Having observed an increased number of referrals to our Accident and Emergency Dept with fractures sustained whilst roller-blading and skateboarding we set about prospectively evaluating the epidemiology and nature of such injuries. 100 successive referrals to the orthopaedic service as a result of roller/skate injuries were evaluated. Childs age, sex, time using apparatus, mechanism of injury, and whether the injury occurred in a dedicated skatepark or on the street was recorded. Whether the child was wearing any form of protective gear and what type was also recorded. The type of fracture and its treatment and follow up was evaluated. All results were recorded on standard excel spreadsheets and statistical analysis was performed using Instat statistics (Graphpad USA 2002). The Male to female ratio in street injuries was 1:1, whereas in ramp injuries 4:1. 60 injuries occurred on the street whereas 40 occurred whilst using the ramps. The mean age was 11.4yrs. The mean length of time using rollerblades/skateboards was 20 and 19 months for street and ramps respectively. The number of children wearing some form of protective gear shows only 20 children out of the 100 studied wore gear, of these 15 wore helmets only. The treatment initiated shows almost 80% of ramp related injuries required formal manipulation under general anaesthesia or open reduction and internal fixation, where as only 25% of street fractures required this form of treatment, The usage of ramps demonstrates an increased relative risk of 4.26 (95% CI 3.5–5.1) This study shows that skateboards and rollerblades still constitute a major component of childhood fracture admissions. Only 20% of children use some form of protective gear whilst skating, this needs to be addressed on a national level. The wearing of helmets whilst protecting the child against head injury do not prevent serious orthopaedic injuries. Wrist guards should be worn by all children skating as the fall onto outstretched hand still remains a childs defensive mechanism when thrown off balance. Almost 75% of all fractures involve the wrist or the forearm. We urge better education and a tighter supervision of children whilst skating. Dedicated skateparks should only be used by experienced and older children and they should at least be supervised during their first attempts at using the parks, 85% of ramp injuries occurred during first or second time users. A child using a skatepark particularily for the first time is three times more likely to sustain a fracture, and almost 4 and a half times more likely to require definitive surgical treatment of this fracture. This constitutes a huge orthopaedic burden as well as it’s associated morbidity and financial costs to the health service. Children should be encouraged to use limb protectors as well as helmets whilst skating and should be supervised more closely during their initial attempts.

A retrospective study was undertaken in our unit to investigate any change in osteomyelitis trends in the last ten years (1991-2001). These results were then compared to 3 previous studies conducted by our unit on childhood osteomyelitis, 1977-1979 45 cases(O’Brien et al)1, 1980-87 (84 cases) and 1988-1991 (54 cases).

149 patients were identified from hospital discharge database with a diagnosis of osteomyelitis between 1991 and 2001. 136 fully completed charts were discovered and included in the study. 22 children did not fulfil the criterion for the diagnosis of acute or subacute osteomyelitis and were excluded. Cellulitis was the actual diagnosis 18/22 cases, leukaemia or other neoplasm in 4/22 cases. 28% of the children 32/114 had acute haematog-enous osteomyelitis with classical signs and symptoms the remaining 72% fell into the subacute osteomyelitis category as described by Gledhill. Table 1 shows the comparison between the 4 studies.

89% of patients underwent 3 phase bone scanning, and 90% of these were positive. Blood cultures were performed in 87% of patients and were positive in 8.5%, 2 patients being positive and symptomatic of Nesseria meningitis, 4 Staph aureus, 2 Strep Pneumonia, 1 staph epidermidis and 1 E.Coli. As compared to previous 3 studies no case of haemophilus influenza type B was encountered. Aspiration was performed in 22 patients and 18 demonstrated bacteria, the two commonest pathogens were Staphylococcus aureus 66% and epider-midis 16%. 8 patients underwent surgical debridement or drilling if clinically septic or because of failure to improve despite medical treatment.

Initial antibiotic treatment comprised of i.v. penicillins and oral fucidin in 92% of patients, the remainder receiving cephalosporins as favoured by physicians or erythromycin if history of hypersensitivity. Antibiotics arethen tailored to clinical picture or culture results. Table 2 shows the changing duration pattern of antibiotic administration.

There were four cases of complications, 2 cases of chronic osteomyelitis and 2 cases of limb shortening both around the knee joint.

Our results correlate well with other authors. Surgery has an ever-decreasing role in the management of osteomyelitis, with conservative antibiotic management and splintage being the treatment of choice. Subacute osteomyelitis is an ever-increasing entity as reflected in other studies. The incidence of osteomyelitis presenting to our unit has fallen to 2.34 per 10000 per yea. A possible explanation may lie in altered host pathogen interactions, increased host resistance, the frequent administration of broad-spectrum antibiotics in general practice. Increased population wealth as experienced in Ireland in the last 8 years may also have a role.

Introduction: Subject to recent literature citing a reduction in ankle range of motion predisposing to ankle fractures in children, we decided prospectively to analyse the passive range of motion in children presenting to our fracture clinic with simple distal radial metaphyseal fractures treated conservatively in cast.

The range of motion was assessed by two observers, and measured using a goniometer in 80 patients. (42 radial fractures and 38 controls) The controls were recruited from children presenting with lower limb injuries and with no prior history of an upper limb injury or neuromuscular condition. The fractures were as a result of simple falls onto the outstretched hand with definite radiological and clinical findings. The range of motion in the contralateral limb was assessed. Both groups showed an equal distribution of dominant and non-dominant limbs.

Results: Both groups were well matched with an average age of 10 and 10.3 years fracture group and control group respectively, and gender 55% male fracture group and 52.5% control group. The m injured group showed a passive range of motion of 1680, whereas the control group showed a higher range of motion of 1820, a difference of 140 (p< . 005 student t-test). A third blinded independent observer of 20 children assessed Intra and interobserver error, and no observer was noted to have higher or lower readings.

Conclusion: Children with radial fractures have a lower passive range of motion of their wrists than Controls. This may contribute to the aetiology of wrist fractures in a paediatric population. An possible explanation may be as cited in original work that children who sustain fractures have less mobility around their joints due to reduced elasticity in their musculoskeletal framework. Simple passive stretching of fracture prone joints should therefore be advised.

Cement is still in common usage in primary and revision arthroplasty surgery. Infection rates in cemented arthroplasties ranges from 1–4% and poses a huge problem for the revision arthroplasty surgeon. Infection in septic implants is biofilm based and almost completely resistant to conventional anti-microbial therapy. Recent papers have questioned the efficacy of using gentamicin-loaded cement in arthroplasty as staphylococcus aureus biofilms will develop on same. The focus of this study was to investigate the efficacy of antibiotic loaded cement in preventing initial bacterial adhesion and subsequent development of a bacterial biofilm in vitro.

Three cements Simplex unloaded, Simplex with erythromycin and Simplex with tobramycin were mixed in a conventional manner, ie vacuum hand mixing in sterile conditions and then injected into pre-moulded PTFE coated cylinder moulds yielding 8 cylinders in each group. The cement cylinders were then removed and exposed to a known pathogenic strain of staphylococcus aureus ATCC—29213-NCTC 12973 in solution 3x10⁶ Colony forming units CFH/ml) for 15 minutes. The cylinders were then removed and cultured for 24 hours at 37°C in RPMI with Glutamine. Cylinders were then removed and subjected to rinsing in PBS to remove any non-adherent bacteria. Cylinders were then sonicated at 50 Hz in Ringer’s solution and adherent biofilms were serially log diluted and plated on Columbia blood agar. Colonies were counted manually. Control cylinders of unloaded cement showed 120,000 CFU/cm² of adherent bacteria whereas loaded cement erythromycin and tobramycin showed 500 and 80 CFU/cm² respectively (p< .0005 Student t-test).

This study shows that loaded cement does not prevent biofilm adhesion in its initial reversible stages whereas unloaded cement does not. This is important since most infected implants are infected at time of primary operation and cements anti-bacterial role beyond the first 48 hours remains questionable, when inflammatory encapsulation of the implant begins. We would therefore question the usage of unloaded cement in primary arthroplasty surgery.

Metallic implants are used frequently in the operative repair of joints and fractures in orthopaedic surgery. Orthopaedic implant infection is chronic and biofilm based. Present treatment focuses on removing the infective substratum and implant surgically as well as prolonged anti-microbial therapy. Biofilms are up to 500 times more resistant than planktonic strains of bacterial flora to antibiotics. Silver coatings on polymers and nylon (catheters, heart valve cuffs, burn dressings) have shown inhibition of this biofilm formation in its adhesion stage. Our aim was to deposit effective, minute, antibacterial layers of silver on orthopaedic stainless steel and titanium K-wires and to investigate the effect of these coatings when exposed to Staphylococcus Aureus biofilms in an in vitro and in vivo environment.

Combining magnetron sputtering with a neutral atom beam (Saddle Field) plasma source at 10⁻⁴ mbar in argon gas at temperatures of 60°C, a silver coating of 99.9% purity was deposited onto stainless steel and titanium orthopaedic K-wires. Coating thickness measurements were obtained using glancing angle x-ray diffraction of glass slides coated adjacent to wires. Magnetron parameters were modified to produce varying thickness of silver. Adhesiveness was examined using Rockwell punch tests. Silver leaching experiments were carried out in phosphate buffered saline at 37°C for 48 hours and using inductive coupled plasma spectrometry to assess leached silver ions. Surface microscopy visualised physical changes in the coatings.

Biofilm adhesion was determined by exposing wires to Staphylococcus Aureus ATCC 29213 – NCTC 12973 for 15 minutes to allow biofilm initiation and adhesion. Wires were then culturing for 24 hours at 37°C in RPMI. Subsequently, wires were sonicated at 50Hz in ringer’s solution and gently vortexed to dislodge biofilm. Sonicate was plated out by log dilution method on Columbia blood agar plates. Bacterial colonies were then counted and changes expressed in log factors.

K-wires were coated with 1 to 50 nm of silver by running the magnetron sputtering at low currents. These coatings showed excellent adhesive properties within the 48 hours exposed with only 3.7% of silver leaching in buffered saline. The silver coated stainless steel wires showed a log 2.31 fold reduction in biofilm formation as compared to control wires (p< .001), Student t-test), the silver coated titanium wires showed a log reduction of 2.06, (p< .001, Student t-test). Animal studies demonstrated enormous difficulty in reproducing biofilm formation and showed a 0.49 log fold reduction in the titanium group when exposed to Staph Aureus (p< .01, Student t-test), the other groups showed no statistically significant reduction.

We have perfected a method of depositing tiny layers of anti-bacterial silver onto stainless steel and titanium, which is anti-infective in vitro but not in vivo. Further studies involving other metal coatings such as platinum and copper are warranted.

Introduction: While the incidence of infection associated with hip and knee prosthesis is low, with the increasing number of arthroplasties being carried out, the total number of such cases is increasing. Also increasing is the number of multi-resistant organisms. These factors have raised questions regarding the optimal antibiotic impregnated cement for use in both spacers and in cemented revisions.

While gentamycin, erythromycin, cefotaxime and vanomycin have a proven record as effective thermostatic antibiotics, newer antibiotics teicoplanin (although used in clinical practice) are as yet untested.

Aim: To investigate the effectiveness of teicoplanin impregnated cement against a Staph Aureus.

Method: A pure culture of Staphlococcus Aureus with known antibiotic sensitivities was obtained. Six batches of Palacos cement were mixed without under sterile conditions. One batch contained cement alone. The other 5 batches were mixed with one of gentamycin, vancomycin, erythromycin, cefotaxime and teicoplanin.

Group 1: A pure culture of over 60 colonies was grown on 5 Columbian blood agar plates. A 1cm spherical sample of each batch of the cement was placed on each plate at regular intervals and allowed to heat and harden.

Group 2: A further 1cm spherical ball of cement from each batch were placed on a further 5 blood agar plates which were then inoculated with the Staph Aureus and the cement was allowed to heat and harden.

Group 3: 24 hours later, the cement was placed on a further 5 blood agar plates which were then inoculated with the Staph Aureus.

Results: Group 1: None of the cement groups had any effect on the established colonies of Staph Aureus.

Groups 2 & 3: The cement without antibiotic had no effect on the growth of the antibiotic even when allowed to heat on the plate. All the other groups including the teicoplanin impregnated cement both initially and after 24 hours, caused a zone of inhibition, ie prevented bacterial growth.

Conclusion:

Heat alone did not affect the growth of the bacteria.

Aim: To investigate the effect of manipulation of the electrochemical environment around metallic implants on bacterial biofilm formation.

Background: The inability to prevent and treat prosthetic bacterial infection is a significant orthopaedic problem. Current antimicrobials are ineffective against bacterial biofilm communities. It is hypothesised that the alteration of the micro-environment could inhibit bacterial adhesion sufficiently to prevent biofilm formation allowing normal tissue integration to occur. Previous work by this group using zinc caused increased bacterial biofilm formation. Platinum being at the opposite end of the galvanic spectrum should cause the opposite effect.

Materials and Methods: Titanium 2mm Kirschner (K) wires (N=14) and Stainless Steel K wires (N=14) were cut into 50mm segments and sterilised. These were inoculated with either Staphylococcus Epidermitis (NC011047) or Staphylococcus Aureus (NC012973) suspensions. Superficial, non-adherent bacteria were removed by serial rinsing in phosphate buffered solution (PBS).

The K wires were added to either the culture media alone or the culture media containing platinum and incubated at 37 degrees for 24 hours. The wires were then removed from the media and rinsed in PBS. Samples were subjected to sonication, to fragment biofilms thereby releasing the bacteria, which were then quantified by serial log dilution technique and manual counting.

The presence of platinum reduced the adhesion of both Staph Aureus and Staph Epidermidis to stainless steel. This reduction was statistically significant using paired t-test (SPSS version 6.0). There was a significant reduction of adhesion with platinum in the Staph Aureus and titanium group while the reduction in the Staph Epidermidis and titanium group did not reach statistical significance.

Conclusion: The use of platinum to manipulate the microcurrent around metallic implants reduces bacterial biofilm formation in vitro. This has obvious clinical implications in prevention of implant infections.