ANTIBIOTIC-IMPREGNATED BONE-CEMENT IN TOTAL HIP-ARTHROPLASTY - AN IN-VIVO COMPARISON OF THE ELUTION PROPERTIES OF TOBRAMYCIN AND VANCOMYCIN

A prospective in vivo quantification was performed to measure the elut ion of tobramycin and vancomycin antibiotics from two commonly used bo ne cements. Forty patients were divided into four groups: Group I, tob ramycin-Simplex; Group II, tobramycin-Palacos-R; Group III, vancomycin -Simplex; and Group IV, vancomycin-Palacos-R. Antibiotic levels were m easured from hemovac wound drainage, urine, and serum and compared wit h control groups who received either intravenous tobramycin or vancomy cin. There were no significant differences in daily mean tobramycin le vels in hemovac samples between Groups I and II. Tobramycin hemovac le vels from Groups I and II were significantly higher than the tobramyci n control group. Similarly, no differences were seen in daily mean van comycin levels of the hemovac samples between Group III and IV; howeve r, the intravenous vancomycin control group had significantly higher l evels in the hemovac fluid than Groups III or IV. Tobramycin in the he movac fluid from Groups I and II was highly bioactive against the cont rol organism. Vancomycin in the hemovac fluid from Groups III and IV h ad variable bioactivity against the control organism. In 30% of the ca ses, no vancomycin was detected in the hemovac fluid, and in these cas es, the hemovac fluid had no effect on the control organism. Tobramyci n elutes to give adequate local tissue levels and releases antibiotic effects when used in an antibiotic bone cement combination. Vancomycin has variable elution properties and is not a predictable additive for the bone cements tested.