THE EXETER POLISHED STEM IN THE LONG TERM: A SURVIVORSHIP STUDY TO THE 33RD YEAR OF FOLLOW-UP AND A STUDY OF STEM SUBSIDENCE

Abstract

Introduction and aims: To study the survivorship and subsidence patterns of the first 433 Exeter stems inserted between 1970 and 1975 by 16 different surgeons utilising first generation cementing techniques.

Method: A survivorship study up to the 33rd year of follow-up was performed, the end-point being revision for aseptic stem loosening. Stem subsidence was measured in all survivors, as well as assessing the grade of cementing, ‘calcar’ resorption, visible cement fractures, focal lysis and radiolucent lines at the interfaces.

Results: Of the 433 hips, 21 were revisions of previously failed hips. 21.7% of patients have had a re-operation of some sort including 3.69% for stem fracture, 3.46% for neck fracture (all from a group of 95 stems with excessively machined necks), 9% for aseptic cup loosening, 3.46% for aseptic stem loosening, 1.84% for infection and 0.23% for recurrent dislocation). For the overall series, with revision for aseptic stem loosening as the end-point, the survivorship is 91.42% (95%CI: 70.82 to 100%). The average age at operation of the survivors was 57.6 years. No significant bone-cement subsidence was found. Mean stem-cement subsidence was 2.15mm, most occurring in the first 5 years and in all but 1 being less than 4mm. Cementing grades were B in 65%, C in 27%, D in 8%. Resorption of the neck (13%) was associated with excessive socket wear or cement left over the cut surface of the neck (the ‘pseudocollar’). Visible cement fractures were found in 14%, none associated with focal lysis, which was seen in 11%.

Conclusions: Although 21.7% of patients in this series of the first 433 Exeter hips to be inserted in Exeter needed a re-operation of some sort, the stem rarely required surgery for aseptic loosening and was associated with benign long-term X-Ray appearances in spite of 1st generation cementing.