Does liberal use of bone wax increase the risk of mediastinitis?
Date First Published:
February 6, 2003
Last Updated:
January 13, 2004
Report by:
Farah Bhatti, Spr Cardiothoracics (Manchester Royal Infirmary)
Search checked by:
Joel Dunning, Manchester Royal Infirmary
Three-Part Question:
In [patients undergoing cardiac surgery] does liberal use of [bone wax] increase the risk of [mediastinitis]?
Clinical Scenario:
You are a registrar performing the sternotomy on a 65 year-old patient who is undergoing an aortic valve replacement, supervised by your consultant. You open the chest and start liberally applying bone wax to the sternal edges. Your Consultant is greatly alarmed and tells you that bone wax is 'poison' and should only be used for friable, bleeding sternums. You heed his advice but wonder what evidence exists for his strongly held views.
Search Strategy:
Medline 1966-07/03 using the OVID interface
Search Details:
[(exp mediastinitis or mediastinitis.af) AND (exp waxes or wax.af)] OR [bone wax.af] LIMIT to review articles.
Outcome:
276 papers were found of which 5 were deemed to be relevant.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Mycobacterium fortuitum epidemics after open-heart surgery. Robicsek F, Daugherty HK, Cook JW, et al. 1978, USA | Case series of 19 patients who presented in a short period with Mycobacterium fortuitum osteomyelitis in the sternum, 2-3 weeks after cardiac surgery | Case series (4) | Outcome | 3 deaths. 15 required reoperation including sternectomy. | No evidence for hypothesis that bone wax caused the outbreak was presented |
| Possible causes | Bone wax was postulated as a possible cause of the outbreak | ||||
| The embolization of bone wax from sternotomy incisions. Robicsek F, Masters TN, Littman L, et al. 1981, UK | Radiolabelled bone wax (5g) was applied to the edges of sternotomies made in 6 dogs. Sternotomy closed with steel wires Lung biopsies were then taken at 15, 30 and 60 mins |
Experimental study | Lung radioactivity | Radioactivity in the lungs doubled from 15mins after bone wax application. Samples from the liver kidney and spleen did not change. | Non-human model |
| Contrast injection to sternum during angiography of a dog | Contrast moves rapidly into the azygos and hemiazygos system and then into the venae cavae and right heart | ||||
| The promotional effect of bone wax on experimental Staphylococcus aureus osteomyelitis. Nelson DR, Buxton TB, Luu QN, et al. 1990, USA | Study to determine the inoculum of S aureus required to induce osteomyelitis in the tibial metaphysis of 84 rats 39 rats had a 1mm hole in tibia inoculated and then the skin closed 45 rats had a 1mm hole with innoculum and then bone wax applied and the skin closed Rats killed at times up to 21 days |
Experimental Study | Inoculum of S. aureus required to infect 50% of animals | Bone wax reduced the amount of inoculum from log 6.9 to log 2.6 bacteria<br>This is a 99.99% smaller inoculum | Non-human non-sternal model used No perioperative anti biotics used |
| Effect of local hemostatics on bone induction in rats: a comparative study of bone wax, fibrin-collagen paste, and bioerodible polyorthoester with and without gentamicin. Solheim E, Pinholt EM, Bang G, et al. 1992, Norway | The tissue response and effect on bone induction was assessed in 150 rats when either bone wax, absorbable fibrin-collagen paste, or a biodegradeable polyorthoester was applied A demineralised bone matrix was inserted into the rectus muscles for 4 weeks. The rats were then killed and the bone samples assessed |
Experimental study | Level of resorbtion | Large amounts of bone wax remained at 4 weeks. Some small amounts of collagen paste remained | Non human trial on non sternal, demineralised bone model in rats |
| Inflammatory reaction | Bone wax induced a much stronger chronic inflammatory reaction | ||||
| Measurements of bone growth | Bone wax significantly reduced bone growth compared to other haemostatics or bone alone | ||||
| Mediastinitis after coronary artery bypass graft surgery: Risk factors and long-term survival. Milano CA, Kesler K, Archibald N, et al. 1994, USA | Study of 6459 consecutive cardiac surgery patients of which 83 developed mediastinitis Also performed a literature search of Medline for risk factors in mediastinitis, 1966-1994 |
Prospective Cohort study and review (2b) | Multivariate analysis of factors implicated in causing mediastinitis | Obesity, NYHA score, Cardiopulmonary Bypass time and previous surgery identified. Presence of bone wax not investigated. Poor haemostasis of sternum was not significant | Bone wax data was not prospectively collected in this study |
| Literature review: Identified 13 studies that described 48 risk factors | Only 1 paper found that poor sternal haemostasis was a significant factor. No studies found bone wax to be significant |
Author Commentary:
There are no human cohort studies that have made the link between bone wax and mediastinitis. One 1978 case series postulated that bone wax may have been a causal factor in an outbreak of Mycobacterium fortuitum mediastinitis, although no evidence was presented to support this. a review by Milano et al. looking for risk factors associated with mediastinitis found no evidence for bone wax causing mediastinitis and in fact associated poor haemostasis with an increased risk.
However animal studies have shown that bone wax can embolise to the lungs, that bone wax markedly reduces the inoculum of Staphlococcus aureus required to cause osteomyelitis, and that bone wax is still present in large quantities 4 weeks post-operatively.
Bone wax is still routinely used in clinical practice and thus a clinical trial is urgently needed in this area to investigate whether these troubling pre-clinical findings cause harm to patients in the clinical setting.
However animal studies have shown that bone wax can embolise to the lungs, that bone wax markedly reduces the inoculum of Staphlococcus aureus required to cause osteomyelitis, and that bone wax is still present in large quantities 4 weeks post-operatively.
Bone wax is still routinely used in clinical practice and thus a clinical trial is urgently needed in this area to investigate whether these troubling pre-clinical findings cause harm to patients in the clinical setting.
Bottom Line:
Animal studies indicate that there are strong reasons for concern over the liberal usage of bone wax.
References:
- Robicsek F, Daugherty HK, Cook JW, et al.. Mycobacterium fortuitum epidemics after open-heart surgery.
- Robicsek F, Masters TN, Littman L, et al.. The embolization of bone wax from sternotomy incisions.
- Nelson DR, Buxton TB, Luu QN, et al.. The promotional effect of bone wax on experimental Staphylococcus aureus osteomyelitis.
- Solheim E, Pinholt EM, Bang G, et al.. Effect of local hemostatics on bone induction in rats: a comparative study of bone wax, fibrin-collagen paste, and bioerodible polyorthoester with and without gentamicin.
- Milano CA, Kesler K, Archibald N, et al.. Mediastinitis after coronary artery bypass graft surgery: Risk factors and long-term survival.