The migration pattern of the Charnley femoral stem: a five-year follow-up RSA study in a well-functioning patient group.

Background: Implant stability is considered vital to long-time implant survival in total hip arthroplasty (THA), since loose implants are reported to be a major cause of hip revision. There is an association between early implant micromotion and increased risk of revision. More implant-specific data are needed to establish acceptable levels of early implant movement.

Materials And Methods: Thirty-five patients (36 hips) undergoing Charnley THA were followed with repeated clinical, radiographic, and radiostereometric analysis (RSA) over 5 years. Twenty-three patients attended 5 years postoperatively.

Results: The patient group was well functioning based on the radiological and clinical evaluations. The stems constantly moved up to 5 years postoperatively, with subsidence, retroversion, and varus tilt, based on the RSA.

Conclusion: Continuous movement of the Charnley stem was observed up to 5 years postoperatively in a well-functioning patient group. The migration data presented herein could be useful when defining acceptable migration limits for certain types of cemented femoral stems.