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[Total hip arthroplasty and femoral head osteonecrosis in renal transplant recipients].

PURPOSE OF THE STUDY
Osteonecrosis of the femoral head is reported in a very variable proportion of renal transplant recipients. When these patients require total hip arthroplasty (THA), immunosuppression and poor bone quality increase the risk of aseptic loosening and infection. In the literature, functional outcome has been satisfactory although rates of early and late complications have varied greatly. The purpose of our work was to determine the long-term outcome in a series of renal graft recipients who underwent THA for osteonecrosis of the femoral head.


MATERIAL AND METHODS
Forty-eight THA were implanted for aseptic osteonecrosis of the femoral head (Ficat grade III and IV) in 32 renal transplant recipients between 1974 and 1995 (21 men and 11 women). Mean age was 30 years at transplantation and 39 years at THA surgery. Thirty patients had been on hemodialysis for a mean 1 year prior to transplantation. Joint disease concerned 2 or more joints in 23 of the 32 patients. Fifteen hips had a surgical history: 8 drillings and 3 head arthroplasties. The THA was implanted under general anesthesia via the posterolateral approach. All implants were fixed with a gentamycin cement. A cephalosporin was used for the antibiotic prophylaxis in 20 cases and a cephalosporin/vancomycin combination in 24. Functional outcome was assessed with the Postel-Merle-d'Aubigné (PMA) score. Functional gain was [(PMAreview-PMApreop)/PMApreop]. General or local complications were recorded at last follow-up. The complete or incomplete nature of lucent lines seen on the last follow-up x-rays and their evolution were also recorded. Reasons for second procedures were noted.


RESULTS
Early complications were: phlebitis (n=1), hematoma (n=7), dislocation (n=1), deep infection (n=2). At last follow-up (mean=5 years 7 months), four patients (6 THA) had died and six (7 THA) were lost to follow-up. Preoperatively, function was scored fair or poor in 91% of the patients. At last follow-up function was scored good, very good, or excellent in 75%. Mean functional gain was 38%. A second operation was necessary for seven THA due to aseptic loosening (mean delay 9 years 10 months), for five others for septic loosening (mean delay 6 years 8 months), and finally for two for instability (one early and the other after more than 2 years). In all, 29% of the THA were reoperated. Two deaths were related to late THA infection. Active lucent lines were observed in 11% of the THA (excepting patients reperated for loosening).


DISCUSSION
The functional gain provided by THA in renal transplant recipients with aseptic osteonecrosis of the femoral head is clearly established. Implant survival remains a problem. The rate of early local complications was high in our series, mainly related to hematoma formation and infection. The infections observed were particularly severe requiring early comprehensive management at onset of clinical signs. For patients with suspected deep infection, we propose an aspiration biopsy of the joint to obtain a bacteriological sample.


CONCLUSION
THA enables good functional outcome for renal transplant recipients suffering from osteonecrosis of the femoral head, but at the cost of a high risk of early and long-term complications not always reported in the literature.