Weight of polyethylene wear particles is similar in TKAs with oxidized zirconium and cobalt-chrome prostheses.
BACKGROUND
The greater lubricity and resistance to scratching of oxidized zirconium femoral components are expected to result in less polyethylene wear than cobalt-chrome femoral components.


OBJECTIVE
We examined polyethylene wear particles in synovial fluid and compared the weight, size (equivalent circle diameter), and shape (aspect ratio) of polyethylene wear particles in knees with an oxidized zirconium femoral component with those in knees with a cobalt-chrome femoral component.


METHODS
One hundred patients received an oxidized zirconium femoral component in one knee and a cobalt-chrome femoral component in the other. There were 73 women and 27 men with a mean age of 55.6 years (range, 44-60 years). The minimum followup was 5 years (mean, 5.5 years; range, 5-6 years). Polyethylene wear particles were analyzed using thermogravimetric methods and scanning electron microscopy.


RESULTS
The weight of polyethylene wear particles produced at the bearing surface was 0.0223 +/- 0.0054 g in 1 g synovial fluid in patients with an oxidized zirconium femoral component and 0.0228 +/- 0.0062 g in patients with a cobalt-chrome femoral component. Size and shape of polyethylene wear particles were 0.59 +/- 0.05 microm and 1.21 +/- 0.24, respectively, in the patients with an oxidized zirconium femoral component and 0.52 +/- 0.03 microm and 1.27 +/- 0.31, respectively, in the patients with a cobalt-chrome femoral component. Knee Society knee and function scores, radiographic results, and complication rate were similar between the knees with an oxidized zirconium and cobalt-chrome femoral component.


CONCLUSIONS
The weight, size, and shape of polyethylene wear particles were similar in the knees with an oxidized zirconium and a cobalt-chrome femoral component. We found the theoretical advantages of this surface did not provide the actual advantage.


METHODS
Level I, therapeutic study. See the guidelines for Authors for a complete description of levels of evidence.
Kim
Young-Hoo
YH
The Joint Replacement Center of Korea, Ewha Womans University School of Medicine, 911-1 MokDong, YangCheon-Gu, Seoul 158-710, Korea. younghookim@ewha.ac.kr
Kim
Jun-Shik
JS
Huh
Wansoo
W
Lee
Kwang-Hoon
KH
D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D002858:Chromium Alloys / Q000032:analysis*; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D005547:Foreign Bodies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D020959:Polyethylene / Q000032:analysis*; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013582:Synovial Fluid / Q000737:chemistry*; D013818:Thermogravimetry; D013997:Time Factors; D015040:Zirconium / Q000032:analysis*
D002858:Chromium Alloys; D020959:Polyethylene; D015040:Zirconium; C028541:zirconium oxide