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Updated: Feb 9, 2026

Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
Activity-related Changes in Cobalt Levels in a Total Hip with a Modular Femoral Stem: A Case Report
Michael S Reich1, Richard H Walker1
1Division of Orthopaedic Surgery, Scripps Clinic, USA.
Introduction:
Femoral neck modularity in total hip arthroplasty (THA) affords the surgeon the ability to optimize femoral neck length, offset, and version, thereby theoretically improving restoration of patient anatomy and biomechanics. The effect of activity on serum metal ion levels in patients with a THA with a mixed-metal modular neck design has not yet been described.
Case Report:
A 63-year-old male underwent THA utilizing a femoral stem with a mixed-metal modular femoral neck. After the stem was voluntarily recalled, he was indicated to be monitored for manifestations ofmodular junction corrosion and development of adverse local tissue reactions (ALTR). An association between activity levels and serial serum cobalt levels was demonstrated.
Conclusion:
In this patient with a THA incorporating a mixed-metal modular femoral neck, modification of activity intensity may have played a role in altered corrosion generation, as indicated by serum metal ion levels. In turn, this may play a role in the progression of ALTR.
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