Abstract
Concern was expressed that the use of a modular stem might produce fretting leading to osteolysis, and component failure. The goal of this study was to document the variability of this design by looking at the long-term i.e. 5–17 year follow-up of the use of a Proximal Modular Stem in primary cases.
A cohort of 955 (S-Rom) primary cases have been followed prospectively and rated clinically using the Harris Hip Score and radiologically after the fashion of Gruen. The mean age was 53. Follow-up was 5–17 years (mean 8.5).
Aseptic loosening requiring revision occurred in three cases (0.3%). One a non-union of a subtrochanteric osteotomy. Two others, one for fracture at the stem tip and one for fracture of the proximal part of a subtrochanteric osteotomy. Harris rating was 78.2% excellent, 16.4% good, 2.3% fair and 3.1% poor. Gruen rating, no lucency in 98.8%, low grade in 1.1% and high grade in 0.1%. Distal osteolysis occurred in two cases. Six patients had persistent thigh pain (type C bone) that was treated by onlay-strut graphs.
There have been no cases of device failures. Other than in the two loose cases distal osteolysis has not been seen. It would appear therefore that the sleeve does act as an adequate seal. There have been no cases of late aseptic loosening and limited thigh pain in type C bone. The authors concluded that this modular device is safe, effective and continue to recommend its use in primary THA.
The abstracts were prepared by Editorial Secretary Jean-Claude Theis. Correspondence should be addressed to NZOA at Department of Orthopaedic Surgery, Dunedin Hospital, Private Bag 1921, Dunedin, New Zealand.
