Abstract
Fundamental engineering considerations indicate that micro-movement of the components of any hip arthroplasty is inevitable: stress cannot exist without strain and vice versa. Micromovement can be classified either as inducible recoverable movement that takes place between the weight-bearing and non-weight-bearing phases of each stride, or as non-recoverable displacement between successive loading cycles.
Radiostereometric analysis is now sufficiently advanced to clarify migration and its significance, and is beginning to throw light on the extent and significance of recoverable cyclical micromovement. We discuss the value of radiostereometric analysis in identifying, early in their in-service life, implants that are likely to loosen.
The abstracts were prepared by Professor M. B. E. Sweet. Correspondence should be addressed to him at The Department of Orthopaedic Surgery, Medical School, University of Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
