A 6-year-old spayed female pit bull mix developed lameness secondary to aseptic loosening of the acetabular component from a total hip replacement (THR) performed at 1 year of age with the standard Zürich cementless THR (Z-THR) system. It was treated by removing the acetabular component and replacing the standard femoral head prosthesis with the larger ‘Cupless’ femoral head. The acetabulum was reamed to accommodate it. The new prosthesis articulated directly with the reamed bone. One year later, the patient had no perceptible lameness and stable implants. Subsequent follow-up found appropriate ambulation and a high degree of owner satisfaction. The Zürich ‘Cupless’ hip replacement system aims to reduce some of the challenges associated with traditional THR. Though functional outcomes have not been scientifically compared with traditional THR, this case suggests it could be considered as an alternative to traditional THR procedures or for revision in cases with aseptic cup loosening.

OBJECTIVE To compare the elution characteristics of amikacin-impregnated calcium sulfate (CaSO4) beads based on different drug concentrations and bead size configurations. SAMPLE Six groups of amikacin-impregnated CaSO4 beads and one negative control group. PROCEDURES Amikacin-impregnated CaSO4 beads were formed with either 500 mg (low-concentration) or 1 g (high-concentration) of amikacin per 15 g CaSO4 hemihydrate powder. The number of beads necessary to approximate 150 mg of amikacin for each of the 3 bead sizes (3 mm, 5 mm, and 7 mm) at both low and high concentrations were placed in 6 mL of phosphate-buffered saline. The saline was sampled at 14 time points over 28 days. Amikacin concentrations were determined using liquid chromatography-mass spectrometry. RESULTS Smaller beads reached higher mean peak concentrations than larger beads (P < .0006). Peak concentrations for the low- and high-concentration groups were 20.5 mg/mL and 27.4 mg/mL, 13.1 mg/mL and 14.0 mg/mL, and 8.85 mg/mL and 6.75 mg/mL for the 3 mm, 5 mm, and 7 mm beads, respectively. Bead size also affected the length of therapeutic duration, lasting 6 days for the 3 mm and 5 mm beads and 9 days for the 7 mm beads. However, this was only statistically evident among the high-concentration beads (P < .044). Antimicrobial concentration within the same bead sizes did not affect elution. CLINICAL RELEVANCE Amikacin-impregnated CaSO4 beads achieved extreme supratherapeutic eluent concentrations. While additional studies are needed, bead size significantly affected elution with smaller beads reaching higher peak concentrations and 7 mm, high-concentration beads demonstrating a longer therapeutic duration than smaller beads.