Simultaneous bilateral total hip arthroplasty is now widely accepted for their economically and functionally advantages than staged total hip arthroplasty. But there is concerning higher demands of blood transfusion than unilateral procedure. Multiple studies suggest that tranexiamic acid (TXA) reduces perioperative blood loss. However there is no report for simultaneous bilateral total hip arthroplasty in these studies. Hypothesis TXA reduces significant blood loss after bilateral total hip arthroplasty. We retrospectively reviewed the records of 12 patients who did not use TXA, and 12 patients who had used TXA. There were no significant differences between the groups in terms of demographics and preoperative Hb. 1g of TXA was administered just before first skin incision and 1g was administered 6 hours after surgery. Intra operative blood loss, the amount of drainage for the first operative day and perioperative Hb changes were recorded.Introduction
Patients and methods
Friction was studied in 67 retrieved cemented cups with 32 mm internal diameter. Friction was measured under 1.0 KN of static load. High molecular hyaluronic acid was adapted as a lubricant. Thirty cups were combined with alumina heads and 37 were combined with metal heads. The years cups were in situ was 7.5 (3.2–13.2) for alumina-polyethylene implants and 8.9 (1.5–15.7) for metal-polyethylene implants (p>
0.05). The revision rate at 15 years follow-up was higher in metal-polyethylene (PE) implants (57%) than that of alumina-PE implants (40%) (p<
0.05). The prevalence of cup loosening was less in alumina-PE implants (12/30) than in metal-PE implants (29/37) (p<
0.01). Less wear was observed in alumina-PE implants (1.15+−0,80mm) than in metal-PE implants (1.62+−0.61mm) (p<
0.01). Less wear was observed in cups without loosening (alumina-PE implants: 1.84+−0.57mm, metal-PE implants: 1.75+−0.51mm) than in those with loosening (alumina-PE implants: 0.69+−0.56mm, metal-PE implants: 1.31+−0.73mm) in both types (alumina-PE implants: p<
0.01, metal-PE implants: p<
0.05). Less wear rate was observed in cups without loosening (alumina-PE implants: 0.11+−0.05 mm/year, metal-PE implants: 0.14+−0.05mm/year) than in those with loosening (alumina-PE implants: 0.17+−0.03 mm/year, metal-PE implants: 0.22+−0.09mm/year) in both types (alumina-PE implants: p<
0.01, metal-PE implants: p<
0.05). The coefficient of friction increased in proportion to the progress of cup wear in both types (alumina-PE implants: r2 =0.217, p<
0.01, metal-PE implants: r2 =0.183, p<
0.01). Relation between the coefficient of friction and stability of implants was not detected in both types, while alumina-PE implants had lower coefficient of friction (0.137+-0.056) than metal-PE implants (0.209+−0.098) (p<
0.01). The torque of metal-PE implants without stem loosening (0.137+−0.053) was larger than that of alumina-PE implants with stem loosening (0.274+−0.088) (p<
0.01). The results suggest that wear has greater influence on stability of implants than the friction, whereas coefficient of friction increases in worn implants.
A method was developed to take radiographs showing the inner articulation of bipolar hip prostheses. By this method, wear was measured in 68 hips whose inner head diameter was 22 mm. Average annual wear rate was 0.17 mm. Osteolysis was observed in 25 hips (37%) and there was no difference between the annual wear rate of hips with and without osteolysis. Studying 19 retrieved prostheses, abrasion of the rim was deeper in hips with osteolysis than those without it. Wear rate of the inner articulation in bipolar hip prosthesis is much larger than that in Charnley’s prosthesis, as linear penetration into the articulation surface reduces the motion range of the inner articulation and this increases impingement and advances rim abrasion.
