Why large-head metal-on-metal hip replacements are painful

• DOI: 10.1302/0301-620x.93b7.26054
• Publication Date: 2011-06-25T21:07:37Z
• Authors: J. P. Cobb; K. Davda; A. Ahmad; S. J. Harris; M. Masjedi; A. J. Hart
• Keywords: Iliopsoas; Femoroacetabular Impingement; Lesser Trochanter

Large-head metal-on-metal total hip replacement has a failure rate of almost 8% at five years, three times the revision conventional replacement. Unexplained pain remains feature this type arthroplasty. All designs femoral component large-head replacements share unique characteristic: subtended angle 120° defining proportion sphere that head represents. Using MRI, we measured contact area iliopsoas tendon on in sagittal reconstruction 20 hips patients with symptomatic femoroacetabular impingement. We also articular extent 40 normal and ten cam-type deformities. Finally, performed virtual resurfacing hips, avoiding overhang metal rim inferomedially. The surface anteriorly posteriorly, but only 100° medially. Virtual surgery normally shaped showed 20° skirt protruding medially where articulates. excessive large-diameter components may cause impingement independently acetabular component. This be postoperative these implants.