Hip simulator

McKellop, H. Shen, F.W. Lu, B. Salovey, R. Campbell, P. The effect of sterilization method and other modifications on the wear resistance of acetabular cups of ultra-high molecular weight polyethylene. A hip simulator study. J. Bone and Joint Surgery 2000, 82 (12), 1708-1725. 

S. Kurtz, C. Muhlstein, A. Edidin, Surface morphology and wear mechanisms of four clinically relevant biomaterials after hip simulator testing, 1. Biomed. Mater. Res. 52 (2000) 447-459. 

Perhaps more relevant from a clinical perspective, UHMWPE is significantly more abrasion resistant and wear resistant than HDPE. The following wear data for UHMWPE and HDPE was collected using a contemporary, multidirectional hip simulator (Edidin and Kurtz 2000). Based on hip simulator data, shown in Figure 1.5, the volumetric wear rate for HDPE is 4.3 times greater than that of UHMWPE. 

From Edidin A.A., and S.M. Kurtz. 2000. The influence of mechanical behavior on the wear of four clinically relevant polymeric biomaterials in a hip simulator, j Arthroplasty 15 321-33 I. 

McKellop H.A., E.W. Shen, P. Campbell, and T. Ota. 1999. Effect of molecular weight, calcium stearate, and sterilization methods on the wear of ultra-high molecular weight polyethylene acetabular cups in a hip simulator. / Orthop Res 17 329-339. 

Ramamurti B.S., D.M. Estok, M. Jasty, and W.H. Harris. 1998. Analysis of the kinematics of different hip simulators used to study wear of candidate materials for the articulation of total hip arthroplasties. / Bone Joint Surg 16 365-369. 

Schroeder D.W., and K.M. Pozorski. 1996. Hip simulator wear testing of isostaticaUy molded UHMWPE effect of EtO and gamma irradiation. In 42nd annual meeting. Orthopaedic Research Society. Atlanta Orthopaedic Research Society. 

Wear testing by Essner and colleagues in a multidirectional hip simulator for up to 10 million cycles demonstrated that Duration exhibited 32% less volumetric wear than air-irradiated control UHMWPE (1997). However, in a recent radiostereometric study by Nivbrant and colleagues, the clinical wear rate of Duration was not significantly different than an air-irradiated control UHMWPE after 2 years of follow-up (2003). 

Details about the in vitro test results with Crossfire have recently been published (Kurtz et al. 2002-2003). In comparison wiOi conventional UHMWPE, Crossfire is associated with more than 90% improvement in median hip simulator wear rate across a broad range of implant designs. The crystallinity and... 

More recently, Greer and colleagues (2003) published the in vitro test results for GUR 1020 and GUR1050, processed with garnrna and electron beam radiation, followed by Marathon thermal processing. Although the mechanical properties were found to be sensitive to molecular weight of the resin, the hip simulator wear rate, in contrast, did not appear to be affected by the resin type. 

Stainless steel + UHMWPE (Charnley) 0.05 Dual hip simulator Velocity = 30 cycles/min Load = 250 kg Duration 1000 h Lub serum Room temperature Simon et al (1973)... 

Co-Cr-Mo (ASTM F75) + UHMWPE 0.044 Hip simulator machine Lub synovial fluid Peak load = 150 kg Walker et al. (1973)... 

Stainless steel + UHMWPE UHMWPE 40 mg/10 cycles NA Ten station hip simulator Range of motion = 46° Lub Bovine blood serum 37° C Load = Oscillating 0-2030 N Frequency = 1 Hz Duration 1 x 10 cycles Highly loaded region of UHMWPE smooth shiny, peeling, pitting. Eyerer et al (1987)... 

Co-Cr-Mo (Protasul-2) + Co-Cr-Mo (Protasul-2) initial wear 10-20 mm linear wear 2-4 mm/10 cycles NA Stanmore Mk III hip simulator 37 mm diameter head Frequency = 1/2 Hz Load = 300-3500 N Duration min. 2.5 x 10 movements/test Lub Ringer s solution w/30% calf serum Equal amount of wear on both compoents. Preferential wear direction, with pronounced grooving. Streicher et al (1990)... 

---