Weight of Polyethylene Wear Particles is Similar in TKAs with Oxidized Zirconium and Cobalt-chrome Prostheses

Abstract

Background The greater lubricity and resistance to scratching of oxidized zirconium femoral components are expected to result in less polyethylene wear than cobaltchrome femoral components. Questions/purposes 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. Patients and 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 lm and 1.21 ± 0.24, respectively, in the patients with an oxidized zirconium femoral component and 0.52 ± 0.03 lm and 1.27 ± 0.31, respectively, in the patients with a cobaltchrome 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. Level of Evidence Level I, therapeutic study. See the guidelines for Authors for a complete description of levels of evidence.

Oxidized Zirconium Bearing Surfaces in Total Knee Arthroplasty: Lessons Learned

“…30 Kim et al compared synovial fluid with respect to PE particle amount, size, and shape in 100 patients with OxZr implants in one knee and CoCr implants in the contralateral knee finding no significant differences. 31 In summary, the clinical results comprising prospective cohort studies, prospective randomized controlled studies, and registry data showed no significant differences in patients with conventional CoCr implants and OxZr implants. Analyses of synovial fluids showed no differences either.…”

“…The authors concluded, that longer follow-up periods are necessary than the investigated 7 years to show a potential benefit of "premium TKAs." 29 Clinical data including results from synovial fluid aspirations were reported by Minoda et al 30 and Kim et al 31 Minoda et al evaluated the amount and size of PE particles in the synovial fluid from six patients with OxZr TKAs and from six patients with CoCr TKAs finding no significant differences in both groups. 30 Kim et al compared synovial fluid with respect to PE particle amount, size, and shape in 100 patients with OxZr implants in one knee and CoCr implants in the contralateral knee finding no significant differences.…”

Do “Premium” Joint Implants Add Value?: Analysis of High Cost Joint Implants in a Community Registry

“…Reports of high-flexion knees [2,23,27], mobile-bearing knees [6,24], oxidized-zirconium femoral components [22,35], and moderately crosslinked polyethylene inserts [29,31,32] have not been consistently associated with either improved function or survival when compared to standard lower-cost designs. All-polyethylene tibial components have demonstrated similar or better mid-to long-term results than metalbacked tibial component designs at lower cost [1,11,12,33].…”

Oxidized Zirconium versus Cobalt-Chromium in TKA: Profilometry of Retrieved Femoral Components

“…Similarly, a retrieval study revealed less surface damage on UHMWPE components that articulated against OxZr than components paired with CoCr [12]. Several series have compared OxZr TKA components with conventional bearing surfaces [14,17,18]; however, superiority of OxZr has not been demonstrated in terms of better implant survival, at least at midterm followup.…”