[Use of combined gallium-technetium scintigraphy to determine the interval before second-stage prosthetic reimplantation in hip arthroplasty infection: a consecutive series of 30 cases].
PURPOSE OF THE STUDY: We report a series of 30 consecutive patients with chronically infected total hip replacement in a prospective treatment protocol that included two-stage revision surgery and scintigraphic monitoring. The serial bone scans were used to evaluate the course of infection, but not for diagnosis. Negative scintigraphic results were required before the second-stage prosthesis reinsertion after laboratory, clinical, and radiographic normalization were achieved. MATERIAL AND METHODS: Between 1987 and 1997, we prospectively followed thirty patients, who had a chronically infected hip arthroplasty treated by the conventional two-stage revision procedure using scintigraphic verification. For the present series, negative bone scan results were achieved in the resected hip before reinsertion of the prosthesis in all patients except one. The labels used were in every case gallium-67 and technetium-99m MDP with early and late (after 30 hours) scans. A scintigraphic result was considered positive if more gallium than technetium was fixed at a site. Our conventional medical and surgical protocol consisted of an initial complete excision of all foreign bodies with systematic parenteral administration of two antibiotics after having searched for the causative organism. A spacer was never used. Tibial pin traction was always applied during the duration of drainage of the wound. The antimicrobial regimen was administered to all of these patients for 3 months. The prosthesis was reinserted when C-reactive protein (CRP) levels returned to normal and negative scintigraphic results were obtained after a period with no antibiotic therapy. Reimplantation of the prosthesis was always performed with preventive antibiotic therapy selected according to the susceptibility of the initial organisms and begun after collecting new intraoperative bacteriological culture specimens. This antibiotic therapy was pursued only for the duration of the postoperative drainage. RESULTS: This follow-up based on combined technetium-gallium bone scans demonstrated two major advantages. First, no recurrence of infection was observed except in the single patient for whom the protocol was not observed. The second advantage was to permit nonarbitrary determination of the moment of reimplantation of the prosthesis, as there is no clear consensus regarding the interval before reinsertion in the literature. The patients underwent the second-stage of hip reconstruction after a mean interval of 9 months. The mean delay before negative scintigraphic results was 7 months. DISCUSSION: This method, which determines the optimum delay before reimplantation reducing the risk of reinfection to a minimum, gave promising results in this prospective study of 30 patients.