Purpose of the study: During the excision period of a two-stage revision arthroplasty, the hip has a low function and an unacceptable leg length discrepancy. The goal of this study was to expose technical details in order to perform a simple articulated cement spacer which could be implanted during this period to improve hip function, to authorize partial weight bearing and to avoid leg length discrepancy.
Material: This method was applied in three two-stage procedures justified because of particular immunodeficiency conditions: a 43 years old man who had bone marrow allograft and immunosuppressive therapy because of leukemia suffering of subacute septic hip arthritis; a 58 years old man suffering of diabetes and active C-hepatitis who had a septic loosening of a total hip arthroplasty (THA); a 76 years old woman suffering of diabetes who had a third septic loosening of THA.
Method: The prosthesis was made of antibiotic-impregnated cement according to organisms antibiotic resistance. The prosthetic junction between head and diaphysis was reinforced with a tibial plate. Prosthetic shape was identical to the one of femoral broaches inserted in the femur after prosthetic and cement removal. The broach size was chosen when mechanical stability in the femur was obtained, and avoided leg length discrepancy after trials with cups. The tibial plate was bent in order to reinforce the junction with regard to the shape of the determined broach. Two doses of antibiotic-impregnated cement were mixed and molded with hands, then the plate was incorporated at the appropriate location, finally the broach was applied on this composite and cement in excess was removed before polymerisation. For prosthetic head, two options were available: to mold the cephalic zone of the cement at the patient acetabulum diameter with a soft aluminium cup previously molded in the acetabulum; to mold the cement cephalic zone with a trial cup in order to obtain a 22 or 28 ball. For this last option, a third dose of antibiotic-impregnated cement was prepared and placed in the acetabulum, a trial femoral head was applied in it to mold the location for the 22 or 28 prosthetic head. Before insertion, a collar was applied on the stem to prevent migration. Active mobilization was encouraged, and partial weight-bearing authorized.
Results: The mean range of hip flexion during period was 60 degrees. The patients were discharged approximatively 12 days after the first stage. Two patients had effective painless partial weight-bearing. The second stage was performed six weeks later on the average. The second procedure was easier than the second stage of a conventional two-stage procedure because of: easy and low hemorrhagic dissection authorized by the prosthesis; low difficulties with soft tissue tension as the prosthesis prevents leg length discrepancy; preservation of the articular space which prevents soft tissue sacrifice during the second stage.
Conclusion: This simple technique is effective to prevent complications related to the excision period of a two-stage hip revision arthroplasty. Likewise, the economical aspect (short delay of hospitalisation, quick functional recovery) should be considered when compared with the excision period of a conventional two-stage procedure.