The AAHKS Clinical Research Award: Intraosseous Regional Prophylaxis Provides Higher Tissue Concentrations in High BMI Patients in Total Knee Arthroplasty: A Randomized Trial.

BACKGROUND: Obesity is an established risk factor for periprosthetic joint infections after total knee arthroplasty (TKA). In obese patients, a larger dose of prophylactic vancomycin based on actual body weight is required to reach therapeutic concentrations. It is unclear how tissue concentrations are affected when intraosseous regional administration (IORA) is used in this population. This study compared tissue concentrations of low-dose vancomycin via IORA vs actual body weight-adjusted systemic intravenous (IV) dose in primary TKA. METHODS: Twenty-two patients with a body mass index (BMI) >35 undergoing TKA were randomized into 2 groups. The IV group received 15 mg/kg (maximum of 2 g) of systemic IV vancomycin and the IORA group received 500 mg vancomycin into the tibia. Subcutaneous fat and bone samples were taken at regular intervals. Tissue antibiotic concentrations were measured using liquid chromatography coupled with tandem mass spectrometry. A blood sample was taken 1 to 2 hours after tourniquet deflation to measure systemic concentration. RESULTS: The mean BMI was 41.1 in the IORA group and 40.1 in the IV systemic group. The overall mean tissue concentration in subcutaneous fat was 39.3 µg/g in the IORA group and 4.4 µg/g in the IV systemic group (P < .01). Mean tissue concentrations in bones were 34.4 µg/g in the IORA group and 6.1 µg/g in the IV systemic group (P < .01). CONCLUSION: Low-dose IORA was effective in the high-BMI population group, providing tissue concentrations of vancomycin 5-9 times higher than systemic administration. IORA optimizes timing of vancomycin administration and provides high tissue antibiotic concentrations during TKA in this high-risk patient group.

The epidemiology of plunging ranula in South Auckland.

OBJECTIVES/HYPOTHESIS: Estimate the incidence rate and provide basic descriptive epidemiologic characteristics of plunging ranulas in a multi-ethnic population. STUDY DESIGN: Case series with chart review. METHODS: The study group comprised all Counties Manukau Health (CMH, Manukau City, Auckland, New Zealand) patients presenting to the CMH Department of Otolaryngology with a diagnosis of plunging ranula from January 2001 to December 2013, as recorded in the departmental case register. Non-CMH domicile patients were excluded. South Auckland comprised the base population, as serviced by CMH. The 2006 New Zealand census data was used for population demographics. RESULTS: A total of 134 cases of plunging ranula were identified. The overall annual crude incidence rate was 2.4 per 100,000 person-years. The gender specific incidence rate for males was 3.2 per 100,000 (95% confidence interval [CI]: 2.5. 3.9) and for females was 2.0 per 100,000 (95% CI: 1.5, 2.6). The overall age-adjusted annual incidence rate was 2.6 per 100,000 (95% CI: 2.1, 3.0). The age-adjusted incidence was highest among Maori (6.7 per 100,000, 95% CI 4.9, 8.4), followed by Pacific Island (4.4 per 100,000, 95% CI 3.2, 5.6), Asian (0.7 per 100,000, 95% CI 0.2, 1.2), and European population (0.6 per 100,000, 95% CI 0.3, 0.8). CONCLUSION: We have quantified for the first time the age-specific and age-adjusted incidence rates for plunging ranula by gender and ethnicity. The results show a likely underlying genetic predisposition for this condition, possibly with a superimposed environmental acquired factor relating to external, minor blunt trauma to the neck. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:2739-2743, 2016.