Polyethylene Wear is Related to Patient-specific Contact Stress in THA
- First Online:
- 222 Downloads
General numerical models of polyethylene wear and THA simulators suggest contact stresses influence wear. These models do not account for some patient-specific factors. Whether the relationship between patient-specific contact stress and wear apply in vivo is unclear.
We therefore determined whether (1) contact stress distribution at the prosthesis-cup interface and (2) hip geometry and cup inclination are related to wear in vivo.
We retrospectively reviewed the radiographs of 80 patients who had aseptic loosening of their THAs as determined by radiographic criteria. We determined linear penetration and volumetric wear using postoperative and last followup radiographs. Contact stress distribution was determined by the HIPSTRESS method. The biomechanical model was scaled to fit the patient’s musculoskeletal geometry of the pelvis, trochanteric position, and cup inclination using the standard postoperative radiograph.
Linear penetration and volumetric wear correlated with peak contact stress. Polyethylene wear was greater in THAs with a medial position of the greater trochanter and smaller inclination of the acetabular cup.
Our observations suggest wear is specific to contact stresses in vivo.
Long-term wear in a THA can be estimated using contact stress analysis based on analysis of the postoperative AP radiograph.
- 4.Brown TD, Bartel DL; Implant Wear Symposium 2007 Engineering Work Group. What design factors influence wear behavior at the bearing surfaces in total joint replacements? J Am Acad Orthop Surg. 2008;16(suppl 1):S101–S106.Google Scholar
- 6.Callaghan J., Rosenberg AG, Rubash HE. The Adult Hip. Ed 2. Baltimore, MD: Lippincott Williams & Wilkins; 2007.Google Scholar
- 10.Geerdink CH, Grimm B; Vencken W, Heyligers IC, Tonino AJ. The determination of linear and angular penetration of the femoral head into the acetabular component as an assessment of wear in total hip replacement: a comparison of four computer-assisted methods. J Bone Joint Surg Br. 2008;90:839–846.PubMedCrossRefGoogle Scholar
- 18.Jasty M., Goetz DD, Bragdon CR, Lee KR, Hanson AE, Elder JR, Harris WH. Wear of polyethylene acetabular components in total hip arthroplasty: an analysis of one hundred and twenty-eight components retrieved at autopsy or revision operations. J Bone Joint Surg Am. 1997;79:349–358.PubMedCrossRefGoogle Scholar
- 27.McKellop HA, D’Lima D, Implant Wear Symposium 2007 Engineering Work Group. How have wear testing and joint simulator studies helped to discriminate among materials and designs? J Am Acad Orthop Surg. 2008;16(suppl 1):S111–S119.Google Scholar