INTRODUCTION: We have previously demonstrated the efficacy of a modified Ti-surface tethered with antibiotics in preventing bacterial colonization. It is not known if coverage of this surface with serum or other physiological material may hinder the bactericidal properties of such a surface.. The in vitro activity and efficacy of such a surface against S. aureus and S. epidermidis was tested following coverage of the surface with serum.

METHODS: Vancomycin was coupled to Ti6Al4V pins by aminopropylation, linker addition, and vancomycin coupling (VancTi). Bactericidal activity was tested in solutions of bacteria (Ci=1×104cfu/ml) incubated with pins±pre-incubation with fetal bovine serum (FBS). Anti fibronectin and anti-vancomycin antibodies were used to detect surface coating or modification. Bacteria were detected by fluorescent labeling (Syto9) or by direct counting after solubilization.

RESULTS: By immunofluorescence, pins were extensively covered with serum fibronectin which did not interfere with the diffuse, intense vancomycin staining. When incubated with S. epidermidis or S. aureus, VancTi showed little colonization compared to control pins (> 95% reduction in cfu).

DISCUSSION: In a physiological environment, implants will be coated with serum proteins. Activity of the VancTi was unaffected by this coating and maintained potent inhibition of bacterial colonization. We have described a surface modification that allows Ti implants to resist colonization and subsequent periprosthetic infection. Such surfaces hold great promise for the prevention and treatment of periprosthetic infections.

Introduction: Diabetes mellitus type 2 (DM II) affects 18.2 million Americans and can cause several chronic and morbid complications. Furthermore, 90% of Americans have radiographic evidence of osteoarthritis by age 40. Diabetes may be an important risk factor for symptomatic osteoarthritis later in life. The aim of our study is to determine if diabetic patients are predisposed to osteoarthritis.

Methods: We conducted a review of the all total knee arthroplasty (TKA) cases performed at our institute during the past two years for end stage osteoarthritis. We excluded TKAs performed for post-traumatic arthritis and patients with inflammatory diseases. Comorbidities and demographical information including age, gender, BMI, and family history were collected from our database. A cross sectional study was performed to analyze the prevalence of DM II in our population. This prevalence was compared to that of diabetics in the general population available from various sources including the National Center for Health Statistics.

Results: Our cohort included a total of 3421 patients (1972 females, 1449 males) who had undergone TKA for end stage osteoarthritis. The average age and BMI were 66 years (range: 39–92) and 32 (range: 21–65) respectively. The prevalence of diabetes mellitus type 2 in our cohort was 12%, while the prevalence of DM II in the general US population currently ranges from 6%–7%.

Discussion: Chronic diabetes causes multiorgan failure via microvascular and macrovascular damage and may possibly lead to degeneration of articular cartilage and eventual arthritis. Based on this study, diabetes appears to be a strong predisposing factor for arthritis. Our laboratory has launched an extensive series of experiments delinating the potential cellular mechanism for such association.

Introduction: We have previously described modification of Ti that renders the implant surface bactericidal and prevents bacterial colonization in vitro. This study evaluates the efficacy of the same surface in preventing periprosthetic infection in a small mammal model.

Methods: Control or VancTi rods were incubated with S. aureus (Ci=104CFU/mL) in TSB containing 0, 5×10-3, 4, or 100 μg/mL vancomycin at 37°C for 24h. Bacteria were detected by fluorescence (Live/Dead BacLight) and imaged by confocal microscopy. Resistance was tested by incubating control or VancTi rods with S. aureus for 0–8 weeks. Adherent bacteria were tested every 7 days on vancomycin screening agar (6μg/mL).

Results: Using a percutanous approach, the intercondylar region of the knee in rats were identified. The intrameduallry canal of the femur was retrograde reamed using an 18-gauge needle. Infection was induced by injection of 103 CFU S. aureus in 150uL of saline into the femoral canal followed by insertion of a 20 mm Ti implant. Animals were harvested at various time points. At harvest, animals were euthanized with CO2.. Detailed analysis including radiographic, micro-CT, histological, bacteriological, and clinical evaluation was performed.

Results: All animals showed signs of infection within the first few post-operative days with increased soft tissue swelling and limited mobility. At 1 week 75% of the animals showed radiographic signs of periprosthetic infection including periosteal reaction, abscess formation, widened canal, bone destruction, and formation of involucrum. PPI could be prevented in 92% of cases when modified Ti-Van was used. In one animal despite the use of antibiotic-tethered implant, PPI occurred partially due to the pin insertion penetrating the bone cortex.

Discussion: Biologically modified implants with bactericidal surface can have a promising role in management of periprosthetic infection. The modified implant described herein contains a nanoscale surface of covalently linked antibiotics that can potentially confer bactericidal properties throughout the life of the implant