Mid-term changes in blood metal ion levels after Articular Surface Replacement arthroplasty of the hip

Abstract

Bone Joint J 2017;(4 Supple B):33-40. AimsOur first aim was to determine whether there are significant changes in the level of metal ions in the blood at mid-term follow-up, in patients with an Articular Surface Replacement (ASR) arthroplasty. Secondly, we sought to identify risk factors for any increases. Patients and MethodsThe study involved 435 patients who underwent unilateral, metal-on-metal (MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). These patients all had one measurement of the level of metal ions in the blood before seven years had passed post-operatively (early evaluation) and one after seven years had passed post-operatively (mid-term evaluation).Changes in ion levels were tested using a Wilcoxon signed-rank test. We identified subgroups at the highest risk of increase using a multivariable linear logistic regression model. Metal-on-metal (MoM) total hip arthroplasties (THAs) gained popularity during the 1990s due to the theoretical advantages of lower wear and a decreased rate of dislocation. Results

Obesity is not associated with hip failure in patients with articular surface replacement of the hip

“…This is consistent with several studies reporting differences in metal ion levels between genders. 12,13,18 Female patients seem to fare worse with these implants, as other studies also have indicated they are at increased risk for revision surgery and ALTR. 19 It has been suggested that the smaller femoral head size used in females undergoing hip arthroplasty may contribute to inferior outcomes.…”

“…Details of this study are explained in previous literature. 12,13 BMI was not required data in the follow-up study of the ASR hip system but was reported nonetheless by many sites. We only included data from centres that reported BMI data on 90% or more of the patients in our analyses in order to eliminate selection bias.…”

Adverse Tissue Reactions and Metal Ion Behavior After Small‐Head Metasul Hip Arthroplasty: A Long‐Term Follow‐Up Study

“…Alternatively, Cr ion levels increased significantly at 5–10 years and remained almost constant. This trend should reflect a time‐dependent change in the balance between ion release from the device and ion excretion or storage (or potential consumption for tissue reactions) 28 , 29 . Renal excretion is the primary clearance mode of Co and Cr ions, but the kidney reportedly eliminates Co ions at a higher rate compared with Cr ions 28 , 29 .…”

“…This trend should reflect a time‐dependent change in the balance between ion release from the device and ion excretion or storage (or potential consumption for tissue reactions) 28 , 29 . Renal excretion is the primary clearance mode of Co and Cr ions, but the kidney reportedly eliminates Co ions at a higher rate compared with Cr ions 28 , 29 . Furthermore, Cr ions bind more readily to proteins than Co ions, allowing Cr accumulation in local soft tissues and precipitation as chromium orthophosphate 39 .…”

“…One potential limitation of metal ion measurement is that individual patients have an undefined variable biologic response to metal ions and particles 26 , 27 . Another limitation can be considered as a time‐dependent change in the balance between ion release from the device and ion excretion or storage (or potential consumption for tissue reactions) 28 , 29 . Therefore, it is of great importance to continuously monitor the long‐term metal ion behavior following MoM THA.…”