[Loss of kidney function caused by implanted gentamicin sponges]. / Nierfunctieverlies door gentamicine-implantatiesponzen.

BACKGROUND: Infected joint replacements can be treated with gentamicin-containing materials for implantation. This may lead to side effects, especially in patients with impaired renal function. CASE DESCRIPTION: A 74-year-old woman underwent two surgeries for an acutely infected hip replacement. Gentamicin sponges (Garacol) were implanted during both interventions. The day after the second operation, her serum gentamicin levels had risen to toxic values. This confirmed the suspicion that she had a kidney impairment which was probably caused by the implanted gentamicin-containing sponges. In order to limit kidney damage, the patient received continuous venovenous haemodiafiltration (CVVHD). Outpatient check-up 3 months later found that the creatinine levels in the serum of the patient had normalised. CONCLUSION: Locally administered gentamicin sponges for implantation can cause therapeutic serum levels leading to systemic side effects. It is advisable to check kidney function before using the sponges. If this is reduced, it is recommended to be cautious when using these sponges for implantation. In case of toxic elevated values, CVVHD can limit kidney damage - which is reversible, given time - by accelerating gentamicin excretion.

Computational assessment of press-fit acetabular implant fixation: the effect of implant design, interference fit, bone quality, and frictional properties.

Patients suffering from rheumatoid arthritis typically have a poor subchondral bone quality, endangering implant fixation. Using finite element analysis (FEA) an investigation was made to find whether a press-fit acetabular implant with a polar clearance would reduce interfacial micromotions and improve fixation compared with a standard hemispherical design. In addition, the effects of interference fit, friction, and implant material were analysed. Cups were introduced into an FEA model of a human pelvis with simulated subchondral bone plasticity. The models were loaded with a loading configuration simulating two cycles of normal walking, during which contact stresses and interfacial micromotions were monitored. Subsequently, a lever-out simulation was performed to assess the fixation strength of the various cases. A flattened cup with good bone quality produced the lowest interfacial micromotions. Poor bone decreased the fixation strength regardless of the geometry of the cup. Increasing the interference fit of the flattened cup compensated for the loss of fixation strength caused by poor bone quality. In conclusion, a flattened cup did not significantly improve implant fixation over a hemispherical cup in the case of poor bone quality. However, implant fixation can be optimized by increasing interference fit and avoiding inferior frictional properties and low-stiffness implants.