The increase in cobalt release in metal-on-polyethylene hip bearings in tests with third body abrasives

Abstract

Hypersensitivity reactions in patients receiving metal-on-metal hip replacements have been attributed to corrosion products as observed by elevated cobalt and chromium ions in the blood. Although the majority of cases are reported in metal-on-metal, incidences of these reactions have been reported in the metal-on-polyethylene patient population. To date, no in vitro study has considered cobalt release for this bearing combination. This study considered four 28 mm and seven 52 mm diameter metal-on-polyethylene bearings tested following ISO standard hip simulator conditions as well as under established abrasive conditions. These tests showed measurable cobalt in all bearings under standard conditions. Cobalt release, as well as polyethylene wear, increased with diameter, increasing from 52 to 255 ppb. The introduction of bone cement particles into the articulation doubled polyethylene wear and cobalt release while alumina particles produced significant damage on the heads demonstrated by cobalt levels of 70,700 ppb and an increased polyethylene wear from a mean value of 9–160 mm3/mc. Cobalt release was indicative of head damage and correlated with polyethylene wear at the next gravimetric interval. The removal of third body particles resulted in continued elevated cobalt levels in the 52 mm diameter bearings tested with alumina compared to standard conditions but the bearings tested with bone cement particles returned to standard levels. The polyethylene wear in the bone cement tested bearings also recovered to standard levels, although the alumina tested bearings continued to wear at a higher rate of 475 mm3/mc. Cobalt release was shown to occur in metal-on-polyethylene bearings indicating damage to the metal head resulting in increased polyethylene wear. While large diameter metal-on-polyethylene bearings may provide an increased range of motion and a reduced dislocation risk, increased levels of cobalt are likely to be released and this needs to be fully considered before being widely adopted.

CoCrMo metal release in metal‐on‐highly crosslinked polyethylene hip implants

“…A clinical study showed that patients with a dual‐taper MoP hip system had much higher Co level in serum than patients with nonmodular stem MoP hip system (Gill, Webb, Sloan, & Beaver, ), suggesting that fretting corrosion was an important releasing source of Co ions. The effect of tribocorrosion in articulation on metal ions in serum of patients with MoP hip implants was not clear although a laboratory study demonstrated an increased Co release with third‐body abrasive at articulating surface in a MoP hip system (De Villiers, Traynor, Collins, & Shelton, ). In this study, we observed that those cases with minimal fretting corrosion but evident tribocorrosion showed relatively high Co and Cr ions in serum (Table , MoP5, and MoP10).…”

Psychiatric Disorders and Genotoxicity Following Primary Metal on Polyethylene Total Hip Arthroplasty and Their Correlation to Cobalt/Chromium Levels

“…13,14 Although the majority of cases of hypersensitivity reactions attributed to corrosion products and elevation of cobalt and chromium ions in the blood were reported in metal-onmetal (MOM) implants, [15][16][17] these reactions have been also reported in the metal-on-polyethylene patients. 18 Although Bijukumar et al 19 showed that the metal wear rate of MOM articulation is approximately 20 times lower than that of MOP articulation, the polyethylene particle wear is reduced in the recently introduced highly cross-linked polyethylene. 20 Scully and Teeny 21 reported pseudo-tumor formation in a case of MOP total hip arthroplasty.…”

Third body damage and wear in arthroplasty bearing materials: A review of laboratory methods

“… Number of studies using either a particle method or scratching the implant surfaces directly and the bearing material combinations used in these, where multiple materials have been investigated, both material combinations have been included, materials characterised as ‘other’ include bearing materials such as PEEK and oxidised zirconium. [ 15 , 23 , 28 , 29 , [31] , [32] , [33] , 42 , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] , [73] , [74] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , [82] , [83] , [84] , [85] , [86] , [87] , [88] , [89] , [90] , [91] , [92] ...…”

“…6 The number of studies using bone, PMMA and metal particles in third body wear simulation; other includes particles such as bone void fillers and hydroxyapatite. [ 15 , 23 , 28 , 29 , 33 , 39 , 42 , 45 , 52 , 54 , 55 , 59 , 61 , 62 , [70] , [71] , [72] , [74] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , [83] , [84] , [85] , 87 , 89 , 90 , 92 , 93 ]. …”