Purpose of the study: Two-stage revision arthroplasty with the use of a spacer is generally accepted as a reliable method for treating infected hip replacements. Spacers made from antibiotic-loaded bone cement give good results in treatment of deep infections, but this technique is demanding in terms of spacer shaping. In addition, the conventional spacer may dislocate or fracture during patient mobilization. We attempted to avoid the disadvantages of conventional spacers by the construction of a cannulated articulating spacer. This is a special implant consisting of a polyethylene acetabulum, a stem, a modular neck and a head. Both the acetabulum and stem are covered with antibiotic-impregnated bone cement. They are subsequently pressed into the bone bed to make impression in the cement. The union of the bone bed with cement, which occurs in conventional implantation, must be avoided. This is achieved by making movements with the implant attached to an insertion handle, and by irrigating the operative field with large volumes of saline. A drain inserted in the canal running along the stem long axis facilitates continuous lavage of the medullary cavity.
Material and methods: A total of 11 patients with deep infection of a hip replacement were treated with the use of a cannulated articulating spacer in the years 2002 and 2003. Seven patients had late hematogenous infections and four had chronic delayed infections. The drains providing lavage stayed in place for about 10 to 12 days or less when three consecutive cultivations of drainage discharge were negative. Antibiotics were administered for at least 6 weeks according to the results of CRP and FW assessment. The reimplantation was planned on the basis of laboratory and clinical findings. The outcome was evaluated using the Harris hip score.
Results: Infection was successfully eradicated in all cases. The average time during which the cannulated articulating spacer was in place was 9.4 weeks. The results, as rated by the Harris hip score, were very good; after reimplantation, the average score was 95.1 points (range, 92 to 99). Even better evidence of the advantages of this method was provided by the increase in the average Harris hip score, which was 35.3 points (range, 26 to 69). No spacer dislocation or any other mechanical complication associated with the implant were recorded.
Discussion: Our results achieved with the cannulated articulating spacers developed in our department, as compared with conventional ones, show that the articulating spacer provides the patient with greater comfort and, therefore, improved quality of life for the period between the removal of a loose prosthesis and reimplantation of a definitive one. This method markedly reduces the risk of failure or dislocation of the temporary implant. In comparison with the PROSTALAC system, which is difficult to obtain and which requires complicated instrumentation, our method is simpler and less expensive. Our results show that the presence of an articulating spacer as a foreign body has no effect on the efficacy of treatment for deep infection.
Conclusions: The procedure for preparing a cannulated articulating spacer described here is a modification of the method used to treat deep infection at the site of a total hip arthroplasty; it is inexpensive and provides markedly greater comfort for the patient. The technique combines the advantages of a two-stage revision involving spacer insertion with the use of lavage. Because patient have no major complaint and there is low risk of implant failure, the method allows us to adjust the reimplantation timing to the course of infection eradication and patients' overall health status.