Factors influencing survivorship of the femoral component after primary low-friction hip arthroplasty

Abstract

Two hundred sixty-seven consecutive primary low-friction arthroplasties, followed for 5–18 years after surgery, were studied to assess the factors influencing survivorship of the femoral component, using the Kaplan-Meier method. The endpoint of survivorship was defined radiographically in two ways: incipient failure (subsidence of the femoral component of ≥2 mm) and definite failure (progressive change of position). Twenty-two femoral components developed incipient failure, and twelve of these advanced to definite failure. A canal filling ratio of the stem of ≥75%, cement extent distal to the stem tip of ≥1 cm, use of an intramedullary bone plug, and an exaggerated valgus alignment of the stem correlated positively with survivorship of the femoral component. Calcar resorption and atrophy of the femoral cortex after surgery were associated with aseptic loosening of the femoral component.