A novel ceramic coating for reduced metal ion release in metal-on-metal hip surgery.

Philippa Tyler,Melanie J Coathup,Tim Marriott,Rikin Hargunani,Jayantilal Meswania,Hannah Wilson,Gordon W Blunn,Tim W R Briggs,Roberta Ferro De Godoy,Imran Khan

doi:10.1002/jbm.b.34268

Abstract

An ovine total hip arthroplasty model was developed to evaluate metal ion release, wear, the biological response and adverse tissue reaction to metal-on-metal (MoM) bearing materials. The performance of an advanced superlattice ceramic coating (SLC) was evaluated as a bearing surface and experimental groups divided into; (1) MoM articulating surfaces coated with a SLC coating (SLC-MoM), (2) uncoated MoM surfaces (MoM), and (3) metal on polyethylene (MoP) surfaces. Implants remained in vivo for 13 months and blood chromium (Cr) and cobalt (Co) metal ion levels were measured pre and postoperatively. Synovial tissue was graded using an ALVAL scoring system. When compared with the MoM group, sheep with SLC-MoM implants showed significantly lower levels of chromium and cobalt metal ions within blood over the 13-month period. Evidence of gray tissue staining was observed in the synovium of implants in the MOM group. A significantly lower ALVAL score was measured in the SLC-MoM group (3.88) when compared with MoM components (6.67) (p = 0.010). ALVAL results showed no significant difference when SLC-MOM components were compared to MoP (5.25). This model was able to distinguish wear and the effect of released debris between different bearing combinations and demonstrated the effect of a SLC coating when applied onto the bearing surface. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1760-1771, 2019.

Highlights

Total hip arthroplasty (THA) is considered one of the most successful procedures in modern surgery and metal-onmetal (MoM) THA was commonly used over the last two decades mainly in young and active patients with arthritis
Results showed heavily scratched femoral head surfaces in FIGURE 6. 3D images showing the surfaces profiles generated from the femoral bearing surface in (A) the superlattice ceramic coating (SLC)-MoM group and (B) the non-coated femoral surface
Theoretical and experimental studies have shown that a reduction in surface roughness of MoM and metal on polyethylene (MoP) bearings can lead to reduced wear, due to improvements in the lubrication and abrasion conditions.[20,21]

Summary

Introduction

Total hip arthroplasty (THA) is considered one of the most successful procedures in modern surgery and metal-onmetal (MoM) THA was commonly used over the last two decades mainly in young and active patients with arthritis. MoM THA, hip resurfacing as well as modular head–neck and neck–stem components with a range of bearing materials have resulted in an increase of local and circulating metal products resulting in high short term failure rates.[1,2,3] Adverse soft tissue reactions in patients with a MoM hip replacement are associated with cobalt (Co) and chromium (Cr) particles released from the implant.[3,4,5] MoM bearings generate approximately 6.7 × 1012–2.5 × 1014 nano-scale (mean size of 30 nm) particles per year This is 13,500-times the number of ultra-high molecular weight polyethylene particles produced from a typical MoP bearing.[6] The smaller particles result in a lower volumetric wear than MoP hips but wider particle dissemination, beyond the peri-prosthetic tissues.[6] Micromotion at the interface between modular junctions and between the female taper (head component) and male taper (stem component), facilitates mechanically assisted crevice (MACC) and fretting corrosion, leading to the production of further amounts of wear debris and metal ion release.[7,8] Corrosion around the head– neck interface is considered a significant source of metal release.[9,10,11] An adverse tissue reaction can result in the development of pseudotumors, which can be granulomatous or cystic lesions, neither infective nor neoplastic and develop in the vicinity of the THA. ALVAL is not unique to tissues surrounding MoM implants, the intensity of lymphocytic infiltrate is greater in association with metal debris from MoM implants than with other bearing surfaces.[13,14] MoM hip implants are rarely used advantages in the use of larger bearings remain, including improved range of motion,[15] reduced risk of revision and in the case of resurfacing devices, conservative bone-preserving surgery where less resection of femoral host bone is required.[16,17]

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