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Hip: J. Hauptfleisch, S. Glyn-Jones, D. J. Beard, H. S. Gill, and D. W. Murray The premature failure of the Charnley Elite-Plus stem: A CONFIRMATION OF RSA PREDICTIONS J Bone Joint Surg Br 2006; 88-B: 179-183 [Abstract] [Full text] [PDF]

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Authors' reply:

Harinderjit S. Gill, David W. Murray   (5 July 2006)

Authors' reply:

Harinderjit S. Gill, David W. Murray   (5 July 2006)

RSA evaluation of the Elite-Plus cemented stem

Graham H Isaac   (13 April 2006)

Authors' reply

H S Gill, D.W. Murray   (13 April 2006)

The premature failure of the Charnley Elite-Plus stem

Professor B M Wroblewski   (13 April 2006)

Unforgiving stem or unforgiving cement?

Brian Derbyshire, Martyn L Porter   (8 February 2006)

Authors' reply: 5 July 2006
Harinderjit S. Gill, University Research Lecturer University of Oxford, David W. Murray Send letter to journal: Re: Authors' reply: richie.gill{at}ndos.ox.ac.uk Harinderjit S. Gill, et al.	Sir, We completely agree with Dr Isaac that the outcome of a hip replacement depends on both the surgical technique and the stem design. In our paper we pointed out that other centres had achieved better results than we had with the Elite-Plus stem, and that this was probably due to differences in surgical technique. We had also previously conducted a detailed study1 to determine which factors were responsible for the failures. In this study we looked at various factors relating to the patient, cementing and surgical technique in patients that we had correctly predicted would fail, and we compared these with those that did not fail. (The assessment of cementing was done in a blinded fashion by Dr Isaac). Interestingly, we found that lack of stem anteversion was significantly related to failure. We did not find any statistically significant relationship between quality of cementing and failure, although this may have been because the numbers studied were small. We are very grateful for the funding provided by Depuy and for the help and support Dr Isaac has given us throughout the study. D.W. MURRAY, FRCS, H.S. GILL, DPhil, Nuffield Orthopaedic Centre, Oxford, UK. 1. Gill HS, Alfaro-Adrian J, Alfaro-Adrian C, McLardy-Smith P, Murray DW. The effect of anteversion on femoral component stability assessed by radiostereometric analysis. J Arthroplasty 2002;17:997-1005.
Authors' reply: 5 July 2006
Harinderjit S. Gill, University Research Lecturer University of Oxford, David W. Murray Send letter to journal: Re: Authors' reply: richie.gill{at}ndos.ox.ac.uk Harinderjit S. Gill, et al.	Sir, We would like to thank Mr Derbyshire and Mr Porter for their interest in our paper. For our study of the Elite-Plus stem we used a cement gun. We therefore selected CMW3 cement, which was the low viscosity cement made by the manufacturer of the stem. Our results were disappointing and not as good as those achieved by other authors. The difference in results is likely to be because of differences in surgical technique or cement. When we used identical techniques and cement with the Exeter stem we achieved good results. We therefore concluded that the Elite-Plus stem was not as forgiving as the Exeter stem. We stand by this conclusion, as we believe that the outcome of polished tapered stems is less likely to be influenced by both surgical technique1 and cement type.2 Mr Derbyshire and Mr Porter make the suggestion that low viscosity cement is less forgiving than high viscosity. This may well be true. However, to establish this we would need evidence that errors in surgical technique cause failure with low viscosity cement but do not cause failure with high viscosity cement. D.W. MURRAY, FRCS, H.S. GILL, DPhil, Nuffield Orthopaedic Centre, Oxford, UK. 1. Gill HS, Alfaro-Adrian J, Alfaro-Adrian C, McLardy-Smith P, Murray DW. The effect of anteversion on femoral component stability assessed by radiostereometric analysis. J Arthroplasty 2002;17:997-1005. 2. Glyn-Jones S, Hicks J, Alfaro-Adrian J. The influence of cement viscosity on the early migration of a tapered polished femoral stem. Int Orthop 2003;27:362-65.
RSA evaluation of the Elite-Plus cemented stem 13 April 2006
Graham H Isaac, Engineer DePuy International Ltd Send letter to journal: Re: RSA evaluation of the Elite-Plus cemented stem gisaac{at}dpygb.jnj.com Graham H Isaac	Sir, DePuy International Ltd has to date not commented on the data presented by the above authors, in various publications, on the performance of the Elite Plus system. However, we consider that the publication of the above paper requires a response because firstly, the conclusions may cause unnecessary concern to surgeons who have used the Elite Plus system and the many thousands of patients who have been the recipients of this device. Secondly, information pertinent to the conclusions of this paper was omitted by the authors in the original publication. The results presented in the above publication were derived from a research study which was designed by the Oxford group and grant-funded by DePuy International Ltd. The outcome of this RSA-like study was followed closely. The results were openly shared and discussed between our research groups. When the two year follow-up data became available this was reviewed. It appeared that the posterior migration/rotation of the Elite Plus stems was greater than that of the comparator system. An examination of the data showed that the difference in posterior migration was not a normal distribution and that four outliers were the principle cause of the difference. If these were excluded then the two cohorts had similar levels of posterior migration. In an attempt to explain these differences a representative of DePuy (GHI), who had no prior access to the outcome data for individual patients, was invited to review 14 sets of Elite Plus radiographs from the study. A number of factors were reviewed, including stem position, orientation, cement mantle thickness, and cement mantle quality. A notable observation was that 9/10 patients in the stable group were registered as having a good cement mantle (as opposed to satisfactory), whilst only 1/4 were so recorded in the unstable group. A further observation was that three patients were identified as having inadequate proximo-medial cement support (‘virtually no cement mantle’, ‘very little cement’, and ‘low neck resection’). When these patients were matched with the RSA data it was found that they were contained within the group of four that had higher than average posterior migration. These observations (together with others) on the appearance of the cement mantle were communicated, verbally and in writing, to the authors who concluded ‘none of your measurements have a significant relationship to posterior head migration’. A further communication was sent to the authors highlighting the relevant observations and concluding, ‘whilst not proven, these small numbers hint that the quality of the cement mantle may be a factor which influences stability’, and that the majority of stems with high posterior movement had ‘radiographic features which would make instability more likely’. Further comments were sought, however the final paper1 completely ignored these issues, and the relationship to radiographic appearance was not discussed. Given the radiographic appearance it is not entirely surprising that these high posterior migration components subsequently went on to fail. Furthermore, it reinforces the belief that the performance of cemented stems is as much dependent upon the quality of cementation as it is on stem design. G.H. ISAAC, PhD, Senior Engineering Fellow - Hips, DePuy International Ltd. Visiting Professor, University of Leeds, UK. 1. Alfaro-Adrian J, Gill HS, Murray DW. Should total hip arthroplasty femoral components be designed to subside? J Arthroplasty 2001;16:598-606.
Authors' reply 13 April 2006
H S Gill, University Research Lecturer University of Oxford, Nuffield Orthopaedic Centre, D.W. Murray Send letter to journal: Re: Authors' reply richie.gill{at}orthopaedic-surgery.oxford.ac.uk H S Gill, et al.	Sir, We thank Professor Wroblewski for his interest in our article and for his comments. With regard to the direction of load, we actually consider this to be the major point; rotation is an important mechanism of failure for cemented total hip stems and rotation is due to loads acting perpendicular to the plane containing the neck and the stem. We feel that rotational stability is an important feature of forgiving cemented total hip stem designs. Failure of fixation of total hip stems is a consequence of a number of factors: the stem design, the implantation technique, and the patient. In our earlier article1 we attempted to reduce the number of variables by standardising the technique and selecting similar patient groups, and the evidence would suggest that failure of fixation in this case is associated with the stem design. With respect to the design rationale of the modification of the shoulder flange, the aim of making the “cement function more efficiently in load transmission” is to prevent loosening of the stem. As loosening is manifested by subsidence, we are confused as to why Professor Wroblewski considers our phrase to be incorrect. We described the surgical technique in our previous publication.1 Professor Wroblewski raises an important point concerning follow-up. We asked our local research ethics committee (LREC) for advice prior to commencing this study, and we were told that we needed to submit an application and seek LREC approval. Again, we thank Professor Wroblewski for his interest and his comments. D.W. MURRAY, FRCS, H.S. GILL, DPhil, Nuffield Orthopaedic Centre, Oxford, UK. 1. Alfaro-Adrian J, Gill HS, Murray DW. Should total hip arthroplasty femoral components be designed to subside? A radiostereometric analysis study of the Charnley Elite and Exeter stems. J Arthroplasty 2001;16:598-606.
The premature failure of the Charnley Elite-Plus stem 13 April 2006
Professor B M Wroblewski, Consultant Orthopaedic Surgeon The John Charnley Research Institute Wrightington Hospital Send letter to journal: Re: The premature failure of the Charnley Elite-Plus stem paulsiney{at}hotmail.com Professor B M Wroblewski	Sir, I read this article with interest and would like to add my comments. The authors do not describe failure of the Charnley Elite-Plus stem; they describe failure of fixation of this stem. The distinction is essential if the source of the problem is to be identified and addressed. They are not correct when quoting our publication1 “…design included a modification of the shoulder flange to reduce subsidence …”. “The dorsal flange was intended to make the upper level of cement function more efficiently in load transmission.”2 The Charnley Elite-Plus stem has a different history. In their surgical technique no mention is made of clearing the calcar3 or the position of the stem within the medullary canal. The importance of the direction of the load out of plane of the neck of the stem4 or the femur5 has been highlighted. These are, however, minor points. The most worrying is their statement: “Ethical approval for the follow-up study was obtained and the patients were contacted…”. Does this mean that the authors did not follow up their patients even when they “predicted that overall, the implant would have a high rate of failure”?6 Why was ethical approval needed to follow up patients? Is this not normal practice? If that is the case, who should bear the continuing burden of clinical, moral, financial and legal responsibility for regular monitoring of the results, other than by “…periprosthetic fracture which was deemed to be secondary to the loosening”? B.M. WROBLEWSKI, FRCS, The John Charnley Research Institute, Wrightington Hospital, Wigan, UK. 1. Wroblewski BM, Fleming PA, Hall RM, Siney PD. Stem fixation in the Charnley low-friction arthroplasty in young patients using an intramedullary bone block. J Bone Joint Surg [Br] 1998;80-B:273-8. 2. Charnley J. Low friction arthroplasty of the hip. Theory & Practice 1979;Springer-Verlag, Berlin:126. 3. Wroblewski BM, Siney PD, Fleming PA, Bobak P. The calcar femorale in cemented stem fixation in total hip arthroplasty. J Bone Joint Surg [Br] 2000;82-B:842-5. 4. Wroblewski BM. The mechanism of fracture of the femoral prosthesis in total hip replacement. Int Orthop. 1979;3:137-9. 5. Wroblewski BM. Transverse load on the hip joint: A subject for further research. Engineering in Medicine 1980:9:163-4. 6. Alfaro-Adrian J, Gill HS, Murray DW. Should total hip arthroplasty femoral components be designed to subside? A radiostercometric analysis study of the Charnley Elite and Exeter stems. J Arthroplasty 2001;16:598-606.
Unforgiving stem or unforgiving cement? 8 February 2006
Brian Derbyshire, Research Fellow Wrightington Hospital, Martyn L Porter Send letter to journal: Re: Unforgiving stem or unforgiving cement? Brian.Derbyshire{at}wwl.nhs.uk Brian Derbyshire, et al.	Sir, We have read this paper with great interest. The authors found that the survival of Elite Plus femoral components at ten years was 83%, dropping to 59% when stems deemed radiologically loose were included. In a sub-group of 19 components, RSA had correctly predicted the failure of four. Blame for the poor survival rate was apportioned to the design of the prosthesis. Compared to the Exeter hip, they consider it to be less 'forgiving', requiring 'perfect' cementing to ensure a good long-term outcome.1 We have carried out a three-year RSA study of 25 Elite Plus femoral components and have only one potential failure (paper in preparation). Additional measurements or assessments, which we believe are essential in order to judge the cause of failure2, were not carried out by the authors. In particular, Barrack3 cementing grades were not assessed and so we do not know whether the radiolucencies found at ten years were present post-operatively. They have published three papers on RSA of the Elite Plus4-6, but this is the first time that they have revealed that low-viscosity cement had been used in all cases. It is surprising that the authors did not refer to the paper by Walton et al7 (published in this journal four months before they submitted their paper) which showed that the Elite Plus performed significantly worse with low-viscosity cement than with high-viscosity cement. This finding is in line with studies of the Norwegian Arthroplasty register which showed an increased failure rate of the Charnley hip associated with low-viscosity cement.8,9 Low-viscosity cements such as Sulfix and CMW3 are no longer used in Norway and Sweden.9 The authors reject the possibility that cement or surgical technique might be the cause of the high failure rate because they used the same cement and technique on Exeter stems, which performed much better. Indeed, in a 12-month RSA study, the Oxford group found no significant differences in the migrations of Exeter hips when low, medium or high-viscosity cements were used.10 However, Furnes et al11 found that Exeter stems had a lower failure rate than Charnley stems when Boneloc cement was used, and this suggests that low/medium-viscosity cement might be more tolerant to 'force closed' prostheses,12 such as the Exeter. In the case of the Elite Plus, therefore, we suggest that it might well be the low-viscosity cement that is not very forgiving, rather than the stem itself. B. DERBYSHIRE, PhD, M.L. PORTER, FRCS, Wrightington Hospital, Wigan, UK. 1. Sherretta SB. Charnley Elite Plus follow-up confirms RSA predictions of high early failure rate. http://www. orthosupersite.com/default.asp?page = void&rid=3909 (accessed 08/02/06). 2. Porter ML, Derbyshire B. Letter to the Editor. J Arthroplasty 2003;18:121-2. 3. Barrack RL, Mulroy RD, Harris WH. Improved cementing technique and femoral component loosening in young patients with hip arthroplasty. J Bone Joint Surg [Br] 1992;74-B:385-9. 4. Alfaro-Adrian J, Gill HS, Murray DW. Cement migration after THR. J Bone Joint Surg [Br] 1999;81-B:130-4. 5. Alfaro-Adrian J, Gill HS, Murray DW. Should total hip arthroplasty femoral components be designed to subside? J Bone Joint Surg [Br] 2001;83-B:598-606. 6. Gill HS, Alfaro-Adrian J, Alfaro-Adrian C, McLardy-Smith P, Murray DW. The effect of anteversion on femoral component stability assessed by radiostereometric analysis. J Arthroplasty 2002;17:997-1005. 7. Walton NP, Darrah C, Shepstone L, Donell ST, Phillips H. The Elite Plus total hip arthroplasty. J Bone Joint Surg [Br] 2005;87-B:458-62. 8. Havelin LI, Espehaug B, Vollset SE, Engesaeter LB. The effect of the type of cement on early revision of Charnley total hip prostheses: a review of eight thousand five hundred and seventy-nine primary arthroplasties from the Norwegian Arthroplasty Register. J Bone Joint Surg [Am] 1995;77-A:1543-50. 9. Espehaug B, Furnes O, Havelin LI, Engesaeter LB, Vollset SE. The type of cement and failure of total hip replacements. J Bone Joint Surg [Br] 2002;84-B:832-8. 10. Glyn-Jones S, Hicks J, Alfaro-Adrian J. The influence of cement viscosity on the early migration of a tapered polished femoral stem. Int Orthop 2003;27:362-65. 11. Furnes O, Lie SA, Havelin LI, Vollset SE, Engesaeter LB. Exeter and Charnley arthroplasties with Boneloc or high viscosity cement: comparison of 1127 arthroplasties followed for 5 years in the Norwegian Arthroplasty Register. Acta Orthop Scand 1997;68:515-20. 12. Huiskes R, Verdonschot N, Nivbrant B. Migration, stem shape, and surface finish in cemented total hip arthroplasty. Clin Orthop 1998;355:103-12.