Abstract
Introduction and Aims: To study the survivorship and subsidence patterns of the first 433 Exeter polished, totally collarless, double tapered, cemented stems that were inserted between November 1970 and the end of 1975 by 16 different surgeons (13 of them in the training grades) utilising first generation cementing techniques.
Method: A survivorship study up to the 33rd year of follow-up, using the contingency table method, was performed for all 433 hips, the end-point being revision for aseptic stem loosening (including also a ‘worst case’ scenario). Stem subsidence in relation to the cement and the bone was measured in all survivors by a single observer on digitised films (magnified 200%) using the Orthochart™ software. Repeated measurements allowed the analysis of intra-observer errors. Stem subsidence, the grade of cementing, ‘calcar’ resorption, visible cement fractures, focal lysis and radiolucent lines at the interfaces were assessed.
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%). When all cases lost to follow-up (28 hips) are regarded as failures, survivorship is 82.9% (95%CI: 58.37 to 100%).
The average age at operation of the survivors was 57.6 years. No significant radiological subsidence between the cement and bone was found. Mean subsidence between the stem and the cement was 2.15mm, most occurring in the first five years and in all but one being less than four. The maximum was 18mm (grade D cementing). 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%.
Conclusion: 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.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
