Original articleEffect of Reduced Diameter Neck Stem on Incidence of Radiographic Cup Loosening and Revisions in Charnley Low-Frictional Torque Arthroplasty
Section snippets
Materials and Methods
The Charnley stem has been consistently manufactured in stainless steel—originally in EN58J then in 316L. The introduction of high nitrogen content stainless steel, together with the cold-forming process (1982), resulted in a very strong material ORTRON (DePuy International, Leeds, UK). Fatigue tests of the 10-mm-diameter neck in ORTRON carried out by the manufacturer “in-house” conformed to the then relevant British Standards Institution test DD91. The first stem was implanted on November 17,
Results
The details of the 2 groups of patients including cup wear data are shown in Table 1. The correlation between the depth of cup penetration and the incidence of cup loosening is shown in Table 2 and Fig. 1 and between the depth of penetration and revision for aseptic cup loosening in Table 3 and Fig. 2. At zero penetration, none of the cups were radiologically loose, and none had been revised, irrespective of the neck diameter. With increasing depth of cup penetration, there was an increasing
Discussion
We set out to establish the effect of reducing the diameter of the neck of the Charnley stem from 12.5 to 10 mm on the incidence of radiographic cup loosening and revisions for aseptic cup loosening. It has been suggested that impingement of the neck of the stem on the rim of the cup is the likely cause 4, 5. The exponential correlation between the depth of cup penetration and the incidence of cup migration has been documented 2, 3. Reducing the diameter of the neck could not be expected to
References (17)
- et al.
Prevalence of impingement in explanted Charnley acetabular components
J Orthop Sci
(1998) - et al.
Activity and socket wear in the Charnley low-friction arthroplasty
J Arthroplasty
(1994) - et al.
Rate of wear in total hip replacement
Clin Orthop
(1975) Charnley low-friction arthroplasty in patients under the age of 40 years
- et al.
Charnley low-friction arthroplasty in the young patient
Clin Orthop
(1992) Direction and rate of wear in Charnley low-friction arthroplasty
J Bone Joint Surg Br
(1985)- et al.
The role of cement in the long term performance and premature failure of Charnley low friction arthroplasties
Eng Med
(1986) - et al.
Quality of the surface finish of the head of the femoral component and the wear rate of the socket in long-term results of the Charnley low-friction arthroplasty
Proc Inst Mech Eng [H]
(1992)
Cited by (0)
Research supported by The Peter Kershaw and The John Charnley Trusts.
No benefits or funds were received in support of the study.