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General Orthopaedics: J. E. Phillips, T. P. Crane, M. Noy, T. S. J. Elliott, and R. J. Grimer The incidence of deep prosthetic infections in a specialist orthopaedic hospital: A 15-YEAR PROSPECTIVE SURVEY J Bone Joint Surg Br 2006; 88-B: 943-948 [Abstract] [Full text] [PDF]

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Rob J Grimer, James E Phillps, Tim P Crane, Malcolm Noy, and Tom SJ Elliott   (27 October 2006)

The incidence of deep prosthetic infections in a specialist orthopaedic hospital

Amol R Chitre, Shahzad Sadiq, Consultant   (18 September 2006)

Authors' reply: 27 October 2006
Rob J Grimer, Consultant Orthopaedic Surgeon , James E Phillps, Tim P Crane, Malcolm Noy, and Tom SJ Elliott Send letter to journal: Re: Authors' reply: rob.grimer{at}roh.nhs.uk Rob J Grimer, et al.	Sir, We would like to thank Messrs Chitre and Sadiq for their interest in our paper. One of the problems with any series dealing with deep infection in patients with joint replacements is the definition one should use to confirm the infection. Unfortunately there is still no gold standard which is 100% reliable, and every surgeon will have come across cases where he or she was convinced there was infection but repeated cultures have all proved negative, and other cases where there are absolutely no stigmata of infection where one culture has grown a low grade organism of uncertain significance. When we started this study in 1987 our Control of Infection Group made a decision as to how we would define deep infection and we adhered to that decision for the next 15 years. We accept that definitions have changed slightly during this time and this is discussed in our paper. We are well aware of the recent studies by Blom et al 1,2 in which they sent patients a questionnaire asking if they had any experience of infection. We were, in fact, so impressed with the papers by Blom and colleagues that we have done an identical study in Birmingham, comparing it with the results of our Control of Infection Group to see which is more accurate. The results of that study are in the final stages of preparation, but we were fascinated to find that a number of patients were adamant that they had an infection when there was absolutely no mention of infection in any of the inpatient or outpatient hospital records. We suspect that the incidence of superficial infection or redness around the wound is probably under-reported in hospitals and possibly over-reported by patients. We believe, however, that the incidence of deep infection is likely to be quite accurate in our series as this will almost always result in the patient returning to hospital. We accept that the longer the period after the operation, the more likely it is that the patient will have moved away and been referred to another hospital, but given that our hospital is a regional referral centre, we think that we will still have kept most of the patients who did develop deep infection. This study did not analyse the risk factors by taking a large group of patients and looking at the risks of those who had diabetes, previous surgery or previous steroid injections. This would be totally outwith the remit and would require review of medical records of all 10,735 sets of notes, which is not something that we plan to do in the near future! The point that Messrs Chitre and Sadiq make about the lack of change in the yearly infection rate is well taken. Over the course of the study, the main changes which took place were the increase in the number of operating theatres from two to eight, but all of them had laminar air flow and some the facility for use of exhaust gowns, although the latter were not used routinely by most surgeons. The main change in practice over the 15 year period of the study was the advent of antibiotic-laden cement. Given the low rate of infection during this period, it would be extremely difficult to prove that any particular factor was responsible for changing the rate of infection from one which has been commendably low throughout. I am afraid, therefore, that whilst we accept some of the criticisms of Messrs Chitre and Sadiq, we disagree with their comments that our series does not represent the true risk of infection of patients undergoing arthroplasty. R.J. GRIMER, FRCS, Consultant Orthopaedic Surgeon, J.E. PHILLIPS, MRCS, Specialist Registrar, T.P. CRANE, MRCS, Specialist Registrar, M. NOY, PhD, Microbiologist, T.S.J. ELLIOT, FRCPath, Consultant Microbiologist, The Royal Orthopaedic Hospital, Birmingham, UK. 1. Blom AW, Taylor AH, Pattison G, Whitehouse S, Bannister GC. Infection after total hip arthroplasty: The Avon experience. J Bone Joint Surg [Br] 2003;85-B:956-9. 2. Blom AW, Brown J, Taylor AH, et al. Infection after total knee arthroplasty. J Bone Joint Surg [Br] 2004;86-B:688-91.
The incidence of deep prosthetic infections in a specialist orthopaedic hospital 18 September 2006
Amol R Chitre, Clinical Fellow Trauma & Orthopaedics Royal Bolton Hospital, Shahzad Sadiq, Consultant Send letter to journal: Re: The incidence of deep prosthetic infections in a specialist orthopaedic hospital amolchitre{at}doctors.org.uk Amol R Chitre, et al.	Sir, We read this paper with interest. This large series of 10,735 patients undergoing primary hip and knee replacements is a landmark study and appears to show very low infection rates of 0.57% and 0.86% respectively in a specialist orthopaedic unit. It does, however, leave questions unanswered. We feel it is difficult to give definitive infection rates having only reviewed those patients on the hospital’s infection register. There may be patients with suspected infection treated either in the community or other hospitals. Without reviewing all patient notes it is impossible to know whether this has occurred. Previous studies have used questionnaires to identify patients with suspected infection. We feel this is more likely to be accurate.1,2 In addition, there is no indication of the number of patients with suspected infection with negative microbiology. Presumably some may have been treated with antibiotics on suspicion of infection, potentially hampering accurate microbiological cultures. It would be interesting to know how many patients had been treated either surgically or with antibiotics. Of note is the mention of patients with pre-existing diabetes or previous intra-articular steroid injection. There is evidence to suggest that both of these factors may increase infection risk,3,4 yet it is unclear whether there is a relative increase in this study. Over the years there was no significant difference in yearly infection rate despite the significant changes in practice - reduced length of stay, patient admission on the day of surgery, etc. Given the time period over which the study takes place, it would be beneficial to know whether there have been changes in surgical protocol, ie. the use of exhaust gowns, prep, laminar-flow theatres, etc. We feel it would be inappropriate to quote this as an absolute infection risk to patients about to undergo arthroplasty given the unanswered questions. A.R. CHITRE, MBChB, MRCS, Clinical Fellow, Trauma and Orthopaedics, S. SADIQ, FRCS(G), FRCS(Tr & Orth), Consultant, Royal Bolton Hospital, Bolton, UK. 1. Blom AW, Brown J, Taylor AH, et al. Infection after total knee arthroplasty. J Bone Joint Surg [Br] 2004;86-B:688-91. 2. Gaine WJ, Ramamohan NA, Hussein NA, Hullin MG, McCreath SW. Wound infection in hip and knee arthroplasty. J Bone Joint Surg [Br] 2000;82-B:561-5. 3. Syahrizal AB, Kareem BA, Anbanadan S, Harwant S. Risk factors for infection in total knee replacement surgery at hospital Kuala Lumpur. Med J Malaysia 2001;56 Suppl D:5-8. 4. Kaspar S, de V de Beer J. Infection in hip arthroplasty after previous injection of steroid. J Bone Joint Surg [Br] 2005;87-B:454-7.