Bone grafting and one-stage revision of THR - biological reconstruction and effective antimicrobial treatment using antibiotic impregnated allograft bone.

Infection of a total hip replacement (THR) is considered one of the most serious complications in orthopaedic surgery. Problems derive from the presence of biofilms with inherent resistance to usual antibiotic treatment and bone defects resulting from infection induced osteolysis. Discussions on the choice of treatment mainly focus on the chance of eradicating the infection in either one or more stages. The advantages of only one operation with regard to patients' satisfaction, functional results and economical burden are evident. However, the fear of re-infection usually leads surgeons to multiple stage procedures, mostly using antibiotic loaded spacers in the interval. Spacers have no effect on biofilms and are associated with a high rate of complications such as breakage or dislocation. Cemented revisions show several disadvantages like reduction of biomechanical properties through added antibiotics, inferior long term results, difficulties of removal in case of recurrence etc. Uncemented implants appear more advantageous but are at risk of becoming colonised by remaining biofilm fragments. To overcome this risk higher local concentrations of antibiotics are needed. Allograft bone may be impregnated with high loads of antibiotics using special incubation techniques, resulting in an antibiotic bone compound (ABC). ABC provides local concentrations exceeding those of cement by more than a 100-fold and efficient release is prolonged for several weeks. At the same time it is likely to restore bone stock, which is usually compromised after removal of an infected endoprosthesis. Based on these considerations new protocols for one-stage exchange of infected THR have been established. Bone voids may be filled with ABC, uncemented implants may be fixed in original healthy bone. Recent studies indicate an overall success rate of more than 90% with one operation, without any adverse side effects. Incorporation of allografts appears as after grafting with unimpregnated bone grafts. One stage revision using ABC together with uncemented implants, should be at least comparable to multiple stage procedures, but with the advantage of the obvious benefits for patients and cost.