Antibiotic Cement in Total Knee Replacement: Always Use It

Steven J.M. MacDonald, M.D., FRCSC
Professor of Orthopaedic Surgery
University of Western Ontario & London Health Sciences Centre
London, ON

Total knee arthroplasty (TKA) has clearly revolutionized the management of the arthritic knee patient and has a tremendous track record of success. One of the most devastating complications following a TKA remains the development of an infection. While estimates vary, the prevalence of peri-prosthetic infection is estimated at approximately 2% following primary TKA and close to 4% following revision TKA. The role for preoperative systemic antibiotics is well established; however, the routine use of antibiotic impregnated bone cement remains controversial.

Clinical Uses
Antibiotic cement has two distinct applications in TKA: 1) treatment and 2) prophylaxis. In an established infection, at the time of the first stage revision in the form of a knee spacer, it is recommended that a high-dose regimen, at least 3.6g of antibiotic per 40g of acrylic cement, be used to assist in treating and eradicating the infection. High-dose antibiotic cement is not appropriate for long-term use as it does have reduced mechanical properties. Prophylaxis of infection is performed using low-dose antibiotic cement, 0.5-1.0g of antibiotic per 40g of cement. Commercially available antibiotic cement is available from many manufacturers. The lower antibiotic dose is required to minimize any mechanical property concerns. Different antibiotics are added (gentamicin, tobramicin, erythromycin) depending on the manufacturer. 

Advantages of Routine Use of Antibiotic Cement
The significant advantage to the routine use of antibiotic cement is the reduction of peri-operative infections following TKA. When the outcome of interest has an incidence of only 2%, very clearly, a randomized clinical trial (RCT) will be under-powered to demonstrate efficacy, unless many patients are enrolled. It is estimated that approximately 8800 patients would have to be entered into an RCT to adequately power it. Despite this, there have been a few RCTs performed. Chiu et al, randomized 340 patients undergoing TKA to either receive cefuroxime impregnated cement or standard cement. No patients in the cefuroxime group developed an infection, 3.1% in the control group did. All of the patients that developed an infection also had the diagnosis of diabetes mellitus (0% infection rate in non-diabetics, 13.5% infection rate in diabetics with standard cement).

If the typical RCT is therefore underpowered, alternate sources of data are required. To answer a clinical question, with a rare outcome, national joint registries have a particular strength. These large databases provide information that is generalizable, providing there has been robust data capturing. The Norwegian Arthroplasty Registry reported on a series of 22,170 patients undergoing total hip arthroplasty. Patients receiving only systemic antibiotics had a 1.8 times higher infection rate than those patients who received a combination of both systemic antibiotics and antibiotic cement. The authors of this paper also reported that the use of antibiotic cement not only reduced the incidence of infected failures, but also the number of cases of aseptic loosening. The conclusion was that some cases of aseptic loosening are actually subclinical infections, and that the addition of antibiotic cement thereby reduced the incidence of these cases. Reports from the Swedish Arthroplasty Registry on 160,000 cases produced almost identical results. Unquestionably the addition of antibiotics to the cement reduced the incidence of periprosthetic infections, implant failures, and the need for revision total joint arthroplasty. There is widespread acceptance, currently, that the routine use of antibiotic cement for all patients undergoing total joint replacements clearly reduces the incidence of perioperative infections and revisions.

Disadvantages of Routine Use of Antibiotic Cement
It must be emphasized that while the advantages of the routine use of antibiotic cement for prophylaxis for all patients are widely accepted and based on the evaluation of thousands of patients, the disadvantages are by and large theoretical.

The first concern often submitted is one of mechanical strength. While this may be an issue with the very high-dose antibiotic cements used in spacers while treating infected implants that are not intended for long-term use, there is no evidence for any concern with the low-dose antibiotic cements. Once again hundreds of thousands of patients have undergone total joint replacements over many decades using antibiotic cement and the only conclusive results have shown a decreased septic and aseptic failure rate. At present there is not a single report of an increased loosening or failure rate with the use of antibiotic cement.

The next concern raised is one of systemic toxicity. Once again there is not a single report of any clinical case of systemic toxicity from low-dose antibiotic cement. In fact, excellent local levels of antibiotics, with low systemic levels, have been found in several series.

The potential for an allergic reaction has been raised as a possible downside to antibiotic cement. Once again, not a single report in all of the orthopaedic literature has been presented to date, despite its routine use for decades.

Cost is sometimes raised as an issue, but clearly this is a weak argument. Certainly antibiotic cement costs more than non-antibiotic cement. Giving patients systemic antibiotics also has a cost associated with it, although no one would advocate stopping that practice. Cost modeling analysis has been performed that indeed demonstrates that when one considers the cost of treating an infected total joint replacement, the routine use of antibiotic cement is in fact cost effective.

The single biggest concern raised is the potential for the development of resistant organisms. Once again, despite its routine use around the world in millions of patients, one has to go back almost 20 years in the orthopaedic literature to find a retrospective report that raised a concern. No definitive data has come out at all linking the development of increased resistant organisms and the routine use of antibiotic cement.

Conclusion
The routine use of low-dose antibiotic cement in total joint arthroplasty has a proven clinical track record. Its advantages are proven, its disadvantages are theoretical. The incidence of both septic and aseptic loosening is reduced. While some may advocate its use in only higher risk patients, it is obvious to every practicing clinician that any patient may develop a peri-prosthetic infection, and to limit its use to only high risk patients when there are no proven disadvantages, is a practice not founded on current clinical evidence.

References

  1. Jiranek W.A., Hanssen A.D., Greenwald S. Antibiotic-loaded bone cement for infection prophylaxis in total joint replacement. J Bone Joint Surg (Am). 88:2487-2500, 2006.
  2. Chiu F.Y., Chen C.M., Lin C.F., Lo W.H. Cefuroxime-impregnated cement in primary total knee arthroplasty: a prospective, randomized study of three hundred and forty knees. J Bone Joint Surg (Am). 84: 759-762, 2002.
  3. Chiu F.Y., Lin C.F., Chen C.M., Lo W.H., Chaung T.Y. Cefuroxime-impregnated cement at primary total knee arthroplasty in diabetes mellitus: A prospective, randomized study. J Bone Joint Surg (Br). 83: 691-695, 2001.
  4. Engesaeter L.B., Lie S.A., Espehaug B., Furnes O., Vollset S.E., Havelin L.I. Antibiotic prophylaxis in total hip arthroplasty: effects of antibiotic prophylaxis systemically and in bone cement on the revision rate of 22,170 primary hip replacements followed 0-14 years in the Norwegian Arthroplasty Register. Acta Orthop Scand. 74:644-651, 2003.
  5. Herberts P., Malchau H. Long-term registration has improved the quality of hip replacement: a review of the Swedish THR Register comparing 160,000 cases. Acta Orthop Scand. 71:111-121, 2000.
  6. Sterling G.J., Crawford S., Potter J.H., Koerbin G., Crawford R. The pharmacokinetics of Simplex-tobramycin bone cement. J Bone Joint Surg (Br). 85:646-649, 2003.
  7. Hope P.G., Kristinsson K.G., Norman P., Elson R.A. Deep infection of cemented total hip arthroplasties caused by coagulase-negative staphylococci.J Bone Joint Surg (Br). 71:851-855, 1989.

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