Bone remodelling in humeral arthroplasty: follow-up using CT imaging and finite element modeling - an in vivo case study

Little material is available in the literature about remodelling of the hum an humerus after implantation of a shoulder hemiarthroplasty. A 73-pear-old patient was examined by CT 4 years after implantation of a right shoulder hemiarthroplasty, and the bone density as represented by Hounsfield values was compared with the contralateral side. Additionally, a three-dimensional finite-element model was generated from the image data and analysed. Bone density was reduced around the prosthesis when compared with the contralate ral side. The stresses were transmitted through the prosthesis, while low b one stresses were found surrounding the prosthesis. Distally from the prost hesis, high stresses were found. On the control side, a more homogeneous st ress distribution was noted. The results could be explained by bone resorpt ion around the prosthesis caused by stress shielding; this hypothesis has t o be confirmed by future studies.