Lisa Renner1,2, Martin Faschingbauer1,3, Tom Schmidt-Braekling4, Friedrich Boettner5. 1. Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA. 2. Department of Orthopedic Surgery, Center for Musculoskeletal Surgery, Charite Universitaetsmedizin, Chariteplatz 1, 10117, Berlin, Germany. 3. Department of Orthopedics and Orthopedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany. 4. Department of Orthopedic Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany. 5. Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA. boettnerf@hss.edu.
Abstract
INTRODUCTION: Metal-on-metal (MoM) bearings are known to release metal ions secondary to wear and corrosion. This may cause local reactions (adverse soft tissue reactions and osteolysis) and systemic effects. Little is known about the exact pattern and the differences between large head MoM total hip replacements (THA) and resurfacings (HR). QUESTIONS: (1) Is there a difference in metal ion concentrations between HR and MoM-THR using the same bearing design (Birmingham Hip Resurfacing System, Smith & Nephew, Inc. Memphis, TN, USA)? (2) Are metal ion levels changing over time in MoM-THA or HR? (3) Do acetabular inclination angle and femoral component size influence cobalt and chromium levels? Is there a correlation between clinical outcome and metal ion levels? MATERIALS AND METHODS: A retrospective analysis was conducted in 77 well functioning unilateral Birmingham HR and 42 well functioning unilateral modular Birmingham MoM-THA (Smith & Nephew, Inc. Memphis, TN, USA) operated on between 2007 and 2012. Blood samples were taken at a minimum of 13 months and subsequent during annual follow-ups. RESULTS: (1) Cobalt levels were significantly higher in MoM-THA compared to HR (p < 0.001). There was no significant difference in chromium levels (p = 0.313). (2) Cobalt is increasing over time in MoM-THA (p = 0.030) whereas metal ions remain stable in HR. (3) Metal ion levels were not affected by acetabular inclination angle and femoral component size in MoM-THA. Chromium levels correlate with the femoral component size (r = -0.240; p = 0.037), the UCLA activity score (r = -0.344; p = 0.003) and the VAS (r = 0.263; p = 0.38) in HR. CONCLUSION: Considering that HR and MoM-THA used the same MoM bearing design, increased cobalt levels may be related to trunnion wear or corrosion. Elevated cobalt levels should raise concern for corrosion related failure in MoM-THA.
INTRODUCTION:Metal-on-metal (MoM) bearings are known to release metal ions secondary to wear and corrosion. This may cause local reactions (adverse soft tissue reactions and osteolysis) and systemic effects. Little is known about the exact pattern and the differences between large head MoM total hip replacements (THA) and resurfacings (HR). QUESTIONS: (1) Is there a difference in metal ion concentrations between HR and MoM-THR using the same bearing design (Birmingham Hip Resurfacing System, Smith & Nephew, Inc. Memphis, TN, USA)? (2) Are metal ion levels changing over time in MoM-THA or HR? (3) Do acetabular inclination angle and femoral component size influence cobalt and chromium levels? Is there a correlation between clinical outcome and metal ion levels? MATERIALS AND METHODS: A retrospective analysis was conducted in 77 well functioning unilateral Birmingham HR and 42 well functioning unilateral modular Birmingham MoM-THA (Smith & Nephew, Inc. Memphis, TN, USA) operated on between 2007 and 2012. Blood samples were taken at a minimum of 13 months and subsequent during annual follow-ups. RESULTS: (1) Cobalt levels were significantly higher in MoM-THA compared to HR (p < 0.001). There was no significant difference in chromium levels (p = 0.313). (2) Cobalt is increasing over time in MoM-THA (p = 0.030) whereas metal ions remain stable in HR. (3) Metal ion levels were not affected by acetabular inclination angle and femoral component size in MoM-THA. Chromium levels correlate with the femoral component size (r = -0.240; p = 0.037), the UCLA activity score (r = -0.344; p = 0.003) and the VAS (r = 0.263; p = 0.38) in HR. CONCLUSION: Considering that HR and MoM-THA used the same MoM bearing design, increased cobalt levels may be related to trunnion wear or corrosion. Elevated cobalt levels should raise concern for corrosion related failure in MoM-THA.
Entities:
Keywords:
Cobalt; Metal ions; Metal-on-metal; Resurfacing; Total hip arthroplasty
Authors: Maximilian F Kasparek; Lisa Renner; Martin Faschingbauer; Wenzel Waldstein; Kilian Rueckl; Friedrich Boettner Journal: Int Orthop Date: 2017-09-19 Impact factor: 3.075