There is considerable interest in ceramic implants because of the increased awareness that wear debris from a metal-on-polyethylene articulation of a total hip prosthesis can cause osteolysis around the implant4. The excellent mechanical and sliding characteristics of ceramic have been reported previously1,5,6,20,21. Nevertheless, some cases of fracture of the ceramic femoral head have been reported8,10,13,16,19,23. The revision operation after this complication may be problematic in terms of the choice of the type of femoral head to be inserted; it may be stainless steel, cobalt-chromium, or ceramic. If a new ceramic femoral head is used, the femoral stem may have to be removed to provide a new Morse taper with the appropriate shape to receive the ceramic head. We do not believe that a stainless-steel femoral head should be used because we observed early abrasion of such a femoral head, with periprosthetic metallosis and rapid failure, in the patient described in this case report.
We present the case of a fifty-four-year-old woman who had considerable wear of a stainless-steel femoral head with extensive periprosthetic metallosis two years after a revision of a total hip replacement because of a fracture of a ceramic femoral head. The aim of this report is to discuss the choice of both the operative procedure and the implant material to be used after such a fracture.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
†Services de Chirurgie Orthopédique (J. A., D. G., and S. L.) and Anatomie-Cytologie Pathologique (M. C. V.), Hôpital Henri Mondor, 51 Avenue du Marechal de Lattre de Tassigny, 94010 Creteil CEDEX, France. E-mail address for Dr. Allain: jalortho@aol.com.
In 1990, a fifty-four-year-old woman was operated on for pain in the left hip secondary to arthrosis of the hip due to congenital hip dysplasia. A total hip arthroplasty was performed with use of a Harris socket with a polyethylene cup (Zimmer, Rungis, France) and a titanium stem with an alumina femoral head that was twenty-eight millimeters in diameter (Biomécanique integrée, Bretigny sur Orge, France). Both components were inserted with cement. The patient had a satisfactory recovery from the operation and had no pain in the hip for five years. In October 1995, she had a sudden onset of pain in the hip. A radiographic examination revealed a fracture of the ceramic femoral head (Fig. 1). A revision was performed, and, at the time of that operation, the femoral head was found to be splintered into multiple fragments. A stainless-steel femoral head (Biomécanique integrée) was inserted onto the original femoral stem, and a new polyethylene liner (Zimmer) was inserted into the original Harris socket. The femoral stem was preserved because there appeared to be no failure of the Morse taper and no signs of loosening.
The initial postoperative course was uneventful, but pain developed in the hip eleven months later. Radiographs made at that time revealed periprosthetic ossification. The sedimentation rate was forty-five millimeters per hour (normal value, less than ten millimeters per hour), and the C-reactive protein level was thirty-six milligrams per liter (normal value, less than ten milligrams per liter).
In June 1997 (eighteen months after the procedure), the patient had increased pain in the left hip. The sedimentation rate was fifteen millimeters per hour, and the C-reactive protein level was six milligrams per liter (normal value, less than five milligrams per liter [the laboratory at which this level was measured was different from the one at which the level was measured previously]). A radiograph of the hip (Fig. 2) revealed a multilobar periprosthetic pseudotumor with peripheral calcification. Migration of the femoral head into the polyethylene liner was noted and was considered to be due to considerable polyethylene wear. The components did not appear to be loose on the radiographs. Therefore, we performed a second revision to remove the periprosthetic pseudotumor and to exchange the femoral head and the cup. Notable metallosis of the surrounding tissues was found during the operative procedure, and a black pseudotumor was present in the muscles; it extended anteriorly from the acetabulum to the proximal third of the thigh and beyond the muscles posteriorly. As much of the mass as possible was resected (Fig. 3). The femoral head had become oval-shaped because of wear (Fig. 4). Black granules were embedded in the cup, but there was no macroscopic evidence of polyethylene wear. The bone at the back of the acetabular socket, which was removed, was infiltrated with the same metallosis.
A new polyethylene cup was inserted with cement into the acetabulum after an acetabular plate had been used to strengthen the fixation. The femoral stem had appeared intact on the preoperative radiographs, and intraoperatively there appeared to be no damage of the Morse taper. Therefore, after some consideration, the stem was not exchanged, and a new, reinforced stainless-steel femoral head (Bionium [Biomécanique integrée], with a toughness of 1000 to 1200 as measured with a Vickers indenter) was used to replace the damaged femoral head. The patient had an uneventful recovery and had no pain in the hip at the most recent follow-up evaluation (at five months).
Histological examination of the periprosthetic pseudotumor revealed an intense and diffuse infiltration of the neosynovial tissue by macrophages and giant multinucleated cells (Fig. 5). In the acetabular area, the granulomatous reaction was particularly rich in giant cells containing large, refractive polyethylene fragments. Large, yellowish fragments of stainless steel were found in the neosynovial tissue that had formed after removal of the original capsule at the time of the first procedure. This stainless-steel material was intensely colored by a Perls reaction. Analysis of the surface of the femoral-head implant with a scanning electron microscope revealed the presence of very adherent particles in the equatorial area (Fig. 6). A microprobe analysis of the energy-dispersive spectrum demonstrated the presence of alumina in these particles. The alumina particles were found in the equatorial area but not in the central bearing surface. The same analysis was done on the polyethylene cup. Examination of the equatorial area with the scanning electron microscope revealed the existence of a third, additional component that, according to the microprobe analysis, was made up of polyethylene wear debris and alumina particles (Fig. 7). Analysis of the bottom of the cup demonstrated an accumulation of abrasive material lying on the polyethylene (Fig. 8). The material was composed of alumina particles (200 to 600 micrometers in size), with some traces of metallic debris.
On the basis of the analysis of both of the components, we believe that the abnormal wear of the stainless-steel femoral head in our patient came about because alumina particles that were still present in the periprosthetic soft tissues amalgamated with the polyethylene wear debris after their appearance. This led to the formation of a third abrasive component (polyethylene wear debris and alumina particles) at the interface between the cup and the femoral head. These particles adhered to the surface of the stainless-steel femoral head and promoted the wear of that component.