Uncemented total hip arthroplasty in chronic hemodialysis patients.

BACKGROUND AND PURPOSE: Whether or not uncemented total hip arthroplasty (THA) can achieve durable fixation of implants to bone in patients on chronic hemodialysis is unknown. We analyzed the 2-13-year clinical outcomes of cementless THA in patients with end-stage renal diseases who were maintained on long-term hemodialysis. PATIENTS AND METHODS: We reviewed the outcome of 23 consecutive uncemented THAs undertaken between 1993 and 2004, in patients with chronic renal failure who had been on long-term hemodialysis (2-18 years). 1 patient died and 2 patients were lost to follow-up within 2 years, leaving 20 hips (20 patients, median age 66 (38-81) years at the time of THA, 11 females) that were reviewed at median 7 (2-13) years postoperatively. RESULTS: Radiographic bone-ingrowth fixation of the components was found in 19 patients. 1 patient had aseptic loosening requiring revision surgery. The median d'Aubigne and Postel score was 10 (8-14) preoperatively and 15 (12-18) at final review. No prosthetic infections were found in any of the patients. INTERPRETATION: Uncemented THA shows promising medium-term results in patients receiving long-term hemodialysis.

High concentration and bioactivity of vancomycin and aztreonam eluted from Simplex cement spacers in two-stage revision of infected hip implants: a study of 46 patients at an average follow-up of 107 days.

This study investigated the release of antibiotics in vivo, from an articulating polymethylmethacrylate (PMMA) spacer used in two-stage revision arthroplasty of infected hip implants. Forty-six patients who underwent two-stage revision hip arthroplasty for infections were managed with an interim PMMA spacer loaded with a high dose of vancomycin and aztreonam. Serum and aliquots of drainage collected after the first-stage surgery, and joint fluid obtained at the time of the second-stage surgery were analyzed for antibiotic concentrations by high performance liquid chromatography and bioactivity by tube dilution bioassay. Following implantation, the highest levels of antibiotics were measured in aliquots of drainage on the first day (vancomycin: 1538.0 +/- 243.6 microg/mL; aztreonam: 1003.5 +/- 323.5 microg/mL), decreasing to 571.9 +/- 169.4 microg/mL for vancomycin and 313.6 +/- 88.3 microg/mL for aztreonam after 7 days. Antibiotic concentrations in serum were very low (vancomycin: 0.58 +/- 0.2 microg/mL, range: 0.1-1.6 microg/mL; aztreonam: 0.46 +/- 0.3 microg/mL, range: 0.1-0.9 microg/mL at 24 h) and there was no systemic adverse effect. At a mean 107 days after the first-stage surgery, the concentrations of antibiotics in joint fluid were well above the minimal inhibitory concentration of most common microorganisms. The released antibiotics were bioactive against the test organisms. Based on the observed results, we confirmed the safety and effectiveness of in vivo drug delivery from antibiotic-impregnated PMMA hip spacers.

Precooling of the femoral canal enhances shear strength at the cement-prosthesis interface and reduces the polymerization temperature.

Preheating of the femoral stem in total hip arthroplasty improves the cement-prosthesis bond by decreasing the interfacial porosity. The main concern, however, is the potential thermal osteonecrosis because of an increased polymerization temperature. In this study, the effects of femoral canal precooling on the characteristics of the cement-stem interface were evaluated in an experimental model for three test conditions: precooling of the femoral canal, preheating of the stem (44 degrees C), and a control in which stems were inserted at room temperature without thermal manipulation of the implant, cement, or bone. Compared to the control group, precooling of the femoral canal and preheating of the stem had similar effects on the cement-stem interface, with greater interfacial shear strength and a reduced porosity. Femoral canal precooling also produced a lower temperature at the cement-bone interface. No difference was found in the ultimate compressive strength of bone cement for the three preparation conditions. Based on this laboratory model, precooling of the femoral canal could improve shear strength and porosity at the stem-cement interface, minimize thermal injury, and maintain the mechanical strength of the cement.

Preparation of epoxy-SiO2 hybrid sol-gel material for bone cement.

An organic-inorganic hybrid material, epoxy-SiO(2), was prepared by incorporating epoxy structure units covalently into a SiO(2) glass network via the sol-gel approach. The precursor was obtained by the reaction of diglycidyl ether of bisphenol A (DGEBA) with 3-aminopropyl trimethoxysilane (APTS). The precursor was then hydrolyzed and co-condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran (THF) at room temperature to yield epoxy-SiO(2) hybrid sol-gel material having a 50 wt % SiO(2) content. Thermal properties of the hybrid material were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hybrid sol-gel material epoxy-SiO(2) was the solid, powder component of bone cement. The liquid component contains bis-phenol-A glycidyl methacrylate (Bis-GMA), triethyleneglycol dimethacrylate (TEGDMA), and methyl methacrylate (MMA) with 25, 55, and 20 vol %, respectively. We discuss the comparison between the new epoxy-SiO(2) bone cement and the commercial Simplex P bone cement. Mechanical properties such as Young's modulus, compressive strength, hardness, and impact strength of the new epoxy-SiO(2) bone cement exceeded those of Simplex P bone cement. The tensile and bending strengths of the new epoxy-SiO(2) bone cement were approximately the same as those of Simplex P bone cement. In order to evaluate the biocompatibility of the new bone cement, an MTT test and optical microscopy were conducted in cell culture. Results indicated that the new epoxy-SiO(2) bone cement exhibits very low cytotoxicity compared with Simplex P bone cement.

Two-stage revision hip arthroplasty for infection: comparison between the interim use of antibiotic-loaded cement beads and a spacer prosthesis.

BACKGROUND: A two-stage revision is a well-accepted method for the treatment of a deep infection of a hip with a joint implant. In the present study, the results associated with the interim use of antibiotic-loaded cement beads were compared with those associated with the interim use of an antibiotic-loaded cement prosthesis. METHODS: One hundred and twenty-eight consecutive patients who were managed with a two-stage revision hip arthroplasty for the treatment of an infection were followed clinically and radiographically for an average of 4.9 years. Cement beads were implanted following resection arthroplasty in the first seventy hips, and a custom cement prosthesis was implanted in the subsequent fifty-eight hips. RESULTS: There was no evidence of recurrent infection in 122 patients (95.3%); the infection-free rates in both groups were similar. The use of a spacer prosthesis was associated with a higher hip score, a shorter hospital stay, and better walking capacity in the interim period; a decreased operative time, less blood loss, and a lower transfusion requirement at the time of reimplantation; and fewer postoperative dislocations. CONCLUSIONS: The present study supports the safety and efficacy of the routine use of an antibiotic-loaded cement prosthesis in the interim between the stages of a two-stage revision procedure for the treatment of an infection at the site of a hip arthroplasty.

Primary total hip arthroplasty without the use of bone cement: a 10-year follow-up of 157 hips.

BACKGROUND: The cementless fixation technique in total hip arthroplasty (THA) was developed to solve clinical problems such as aseptic loosening and osteolysis which were thought to be associated with the use of bone cement. This retrospective study reports our mid-term results with cementless THA. METHODS: A series of 173 consecutive, unselected cementless THA procedures using the Omnifit prosthesis was performed by a single surgeon. Sixteen hips were excluded from the study because of insufficient follow-up evaluation. One hundred and fifty-seven THAs with an average follow-up period of 10.2 (range, 5-12) years were retrospectively reviewed. RESULTS: The overall revision rate was 7.0%. Ninety-five percent of unrevised hips achieved a Merle D'Aubigne hip score of 16 points or above. Radiographically, bone ingrowth occurred in all unrevised cups, and in 95% of unrevised stems. Osteolytic lesions, seen on 28.1% of femora and 8.9% of pelvises, appeared at an average of 3.8 years postoperatively. Femoral osteolytic lesions were confined to the proximal Gruen zones 1 and 7. The mean annual polyethylene wear rate was 0.15 mm. Approximately 1/3 of the hips were noted to have excessive wear. CONCLUSION: These results suggest that cementless Omnifit THA provides stable fixation for as long as 12 years after implantation. Of significant concern is the high incidence of excessive polyethylene wear and associated osteolysis. Our experience also indicates that a femoral stem with a circumferential porous coating in the proximal region can protect the femur from distal osteolysis.