Do Oxidized Zirconium Femoral Heads Reduce Polyethylene Wear in Cemented THAs? A Blinded Randomized Clinical Trial

Abstract

Background Charnley low-friction torque total hip arthroplasty (THA) remains the gold standard in THA. The main cause for failure is wear of the socket. Highly crosslinked polyethylene (HXLPE) has been associated with reduced wear rates. Also, oxidized zirconium has shown in vitro reduced wear rates. However, to our knowledge, there are no data comparing oxidized zirconium femoral heads with metal heads against HXLPE or ultrahigh-molecular-weight polyethylene (UHMWPE) when 22.25-mm bearings were used, which was the same size that performed so well in Charnley-type THAs. Questions/purposes We hypothesized that after a minimal 4-year followup (1) use of HXLPE would result in lower radiographic wear than UHMWPE when articulating with a stainless steel head or with an oxidized zirconium head; (2) use of oxidized zirconium would result in lower radiographic wear than stainless steel when articulating with UHMWPE and HXLPE; and (3) there would be no difference in terms of Merle d'Aubigné scores between the bearing couple combinations. Methods One hundred patients were randomized to receive cemented THA with either oxidized zirconium or a stainless steel femoral head. UHMWPE was used in the first 50 patients, whereas HXLPE was used in the next 50 patients. There were 25 patients in each of the four bearing couple combinations. All other parameters were identical in both groups. Complete followup was available in 86 of these patients. Femoral head penetration was measured using a validated computer-assisted method dedicated to all-polyethylene sockets. Clinical results were compared between the groups using the Merle d'Aubigné score. Results In the UHMWPE series, the median steady-state penetration rate from 1 year onward was 0.03 mm/year (range, 0.003-0.25 mm/year) in the oxidized zirconium group versus 0.11 mm/year (range, 0.03-0.29 mm/year) in the metal group (difference of medians 0.08, p\0.001). In the HXLPE series, the median steady-state penetration rate from 1 year onward was 0.02 mm/year (range, À0.32 to 0.07 mm/year) in the oxidized zirconium group versus 0.05 mm/year (range, À0.39 to 0.11 mm/year) in the metal group (difference of medians 0.03, p \ 0.001). The Merle d'Aubigné scores were no different between the groups with a median of 18 in each of the groups (range, 16-18). Conclusions This study demonstrated femoral head penetration was reduced by oxidized zirconium when compared with metal on both UHMWPE and HXLPE. However, apart the metal-UHMWE group, all other groups had a steady-state penetration rate well below the osteolysis threshold with a low difference between groups that

Wear performance of cobalt chromium, ceramic, and oxidized zirconium on highly crosslinked polyethylene at mid-term follow-up

“…However, Zaoui et al at 4 years follow-up did find a significant reduction (p < 0.001) in wear rate with OxZr (0.02 mm/year) over CoCr (0.05 mm/year) against highly crosslinked polyethylene in all-poly cups (Smith & Nephew Reflection) using the Martell method. 21 Wear may not be the most important long-term issue in modern highly crosslinked polyethylene bearings for total hip arthroplasty. Corrosion at the head-neck junction of the femoral components may be a clinical problem limiting the longevity of these implants.…”

Are Oxinium Femoral Heads Superior to Alternative Bearing Surface Materials? A Systematic Review

“…7,26 Proponents of the use of OxZr claim that it leads to a reduced wear rate when compared with metal femoral heads, but a similar wear rate when compared with ceramic alternatives. 15,18,21 As THA is performed in a progressively younger patient population, there is a higher emphasis placed on differences in revision rates and PE wear with the various component options. Further work needs to evaluate the longterm outcomes comparing OxZr femoral heads with other bearing surface combinations in THA.…”

“…Zaoui et al and Kadar et al reported no revisions in their cohorts with 2-and 6-year follow-up, respectively. 15,17 Morison et al illustrated a Kaplan-Meier curve demonstrating a 94.1% (CI or confidence interval 91.5-96.6%) cumulative survival at 8 years, with no significant difference between any of their studied bearing surface combinations (CoCr/OxZr vs. UHMWPE/XLPE or silane cross-linked polyethylene). 18 This study alongside Jassim et al and Jonsson et al showed revisions were only secondary to infection and recurrent dislocation among the studies ultimately included in this systematic review.…”

“…12,13 This novel design has translated clinically to midterm in vitro studies demonstrating reduced linear and volumetric wear of PE liners when compared with CoCr, ceramic, and steel femoral heads. [14][15][16] There have been published reviews comparing ceramic and metal femoral heads in aggregate, but none that have included OxZr as a comparison group. We sought to undertake a systematic review to determine if there is a difference in revision rates, our primary outcome measure.…”

Liner dissociation leading to catastrophic failure of an Oxinium femoral head

“…The combination of a fatigue-resistant substrate underneath an oxidized, ceramicized surface was designed to emulate superior wear and scratch properties of ceramics while minimizing the risk for brittle fracturing [16] , [17] . This novel design has translated clinically to midterm in vivo studies demonstrating reduced linear and volumetric wear of polyethylene (PE) liners when compared with cobalt-chromium (CoCr), ceramic, and steel femoral heads [18] , [19] , [20] .…”