Prevention of infection after joint replacement - is Betadine lavage effective

We note that some shoulder arthroplasty surgeons use Betadine (Povidone Iodine, PI) lavage in an attempt to reduce the risk of infection. Two recent studies of patients having hip and knee arthroplasties fail to support this practice.

Use of Povidone-Iodine Irrigation Prior to Wound Closure in Primary Total Hip and Knee Arthroplasty An Analysis of 11,738 Cases

These authors identified 5,534 primary THA and 6,204 primary TKA procedures. Cases were grouped on the basis of whether or not the wound was irrigated with 1 L of 0.25% Betadine prior to closure. Betadine irrigation was used in 1,322 (24%) of the THA cases and in 2,410 (39%) of the TKA cases.

The rate of reoperation for infection as assessed at 3 months following THA was similar between those who received dilute PI irrigation (0.9%) and who did not (0.7%) (p = 0.7). At 1 year, the rate of reoperation for infection was similar between those who received dilute PI irrigation (0.7%) and those who did not (0.9%) (p = 0.6). After using the propensity score, there was no difference between the groups in the risk of septic reoperations. For TKA, the rate of reoperation as assessed at 3 months was similar between those who received dilute PI irrigation (0.8%) and those who did not (0.3%) (p = 0.06). At 1 year, there was a greater rate of reoperations for infection among those who received dilute PI irrigation (1.2%) compared with those who did not (0.6%) (p = 0.03). However, there was no difference in the risk of septic reoperations between the groups after using the propensity score.


Povidone-Iodine Wound Lavage to Prevent Infection After Revision Total Hip and Knee Arthroplasty An Analysis of 2,884 Cases

These authors assessed the effectiveness of Betadine irrigation in reducing infection following revision total hips (THA) and and total knees (TKA).  Betadine lavage was employed in 27% of the revision THA cases and 34% of the revision TKA cases

After adjusting for baseline differences between the groups using the propensity-score weighted models, they found no significant difference in the rate of reoperation for infection at 3 months (p = 0.58 for revision THA, and p = 0.06 for revision TKA) and at 12 months (p = 0.78 for revision THA, and p = 0.06 for revision TKA). Nonetheless, the hazard ratios from the propensity-score model trended higher for patients who received Betadine lavage: 1.6 and 1.3 for revision THA at 3 and 12 months, respectively, and 2.9 at both 3 and 12 months for revision TKA.

They noted a trend toward higher rates for reoperation for infection among patients who received PI irrigation.

Comment: These studies do not provide support for the use of Betadine lavage in the prevention of revision for infection in primary or revision total hip and knee arthroplasty. In the discussion they provide evidence of the potential cytotoxic effects of Betadine lavage.

The authors do not provide information on the bacteria associated with reoperation for infection in these cases. 

While it is recognized that different bacteria are commonly associated with periprosthetic infections of the shoulder, this articles may prompt reconsideration of the use of Betadine lavage.
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Propionibacterium - hip and knee surgeons be aware!

These authors reviewed patients infected with P. acnes after total hip (12 cases), knee (18 cases)  and shoulder (35 cases) arthroplasty. Patients were included if they met the Musculoskeletal Infection Society criteria and were excluded if they had a polymicrobial culture. 74% of these patients were men.

Median ESR was significantly higher in the knee (38.0mm/h, IQR 18.0–58.0) and hip (33.5 mm/h, IQR 15.3–60.0) groups compared to the shoulder group (11.0 mm/h, IQR 4.5–30.5). 

C-reactive protein levels were higher in the knee (2.0 mg/dl, IQR 1.3–8.9) and hip(2.4 mg/dl, IQR 0.8–4.9) groups compared to the shoulder group (0.7 mg/dl, IQR 0.6–1.5). 

Median synovial fluid WBC was significantly higher in the knee group than shoulder group (19,950 cells/mm3, IQR 482–60,063 vs 750 cells/mm3, IQR 0–2825, respectively). 

Peripheral blood WBC levels were similar between groups, as was mean time of P. acnes growth in culture. 

Clindamycin resistance was present in all groups. 

The authors concluded that "the manner in which a patient with P. acnes PJI presents is joint specific. Inflammatory markers were significantly higher in the knee and hip groups compared to the hip and shoulder groups, and long hold anaerobic cultures up to 14 days are necessary to accurately identify this organism."

Comment: This study indicates that knee and hip surgeons must join shoulder surgeons in being aware of the presence of Propionibacterium in the wounds of patients coming for revision arthroplasty. This study does not provide data on the rate of Propionibacterium identification in their revision surgery. It also does not indicate whether it is the routine of their surgeons to routinely send specimens for Propionibacterium-specific cultures. Unless cultures are sent and properly cultured, the presence of this organism will be missed. 

This point is driven home by an article from 1999:

Detection of prosthetic hip infection at revision arthroplasty by immunofluorescence microscopy and PCR amplification of the bacterial 16S rRNA gene.

These authors compared the detection rates of bacterial infection of hip prostheses by culture and nonculture methods were compared for 120 patients with total hip revision surgery. 

By use of strict anaerobic bacteriological practice during the processing of samples and without enrichment, the incidence of infection by culture of material dislodged from retrieved prostheses after ultrasonication (sonicate) was 22%.

Bacteria were observed by immunofluorescence microscopy in 63% of sonicate samples with a monoclonal antibody specific for Propionibacterium acnes and polyclonal antiserum specific for Staphylococcus spp. The bacteria were present either as single cells or in aggregates of up to 300 bacterial cells. These aggregates were not observed without sonication to dislodge the biofilm. Bacteria were observed in all of the culture-positive samples, and in some cases in which only one type of bacterium was identified by culture, both coccoid and coryneform bacteria were observed by immunofluorescence microscopy. Bacteria from skin-flake contamination were readily distinguishable from infecting bacteria by immunofluorescence microscopy. Examination of skin scrapings did not reveal large aggregates of bacteria but did reveal skin cells. These were not observed in the sonicates.

Bacterial DNA was detected in 72% of sonicate samples by PCR amplification of a region of the bacterial 16S rRNA gene with universal primers. All of the culture-positive samples were also positive for bacterial DNA. Evidence of high-level infiltration either of neutrophils or of lymphocytes or macrophages into associated tissue was observed in 73% of patients.

Note the prevalence Propionibacterium.

In conclusion, this study implicates unrecognized infection as a potential major cause of prosthetic hip failure. IFM allows a rapid quantitative and qualitative assessment of infected prostheses and distinguishes the bacteria from the infected prostheses from bacteria that may result from skin contamination. The IFM results indicate that 63% of retrieved hip prostheses may be colonized with bacteria. 16S rRNA genes were detected from 72% of retrieved prostheses. We are investigating the nature of the bacteria detectable by PCR amplification but not by IFM.

Their results indicate that the incidence of prosthetic joint infection is grossly underestimated by current culture detection methods.

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Variability in Costs Associated with Total Hip and Knee Replacement Implants. JBJS

Variability in Costs Associated with Total Hip and Knee Replacement Implants. JBJS

The authors point out that the average implant cost per case varied by over 600% ($1797 to $12093) for total knee replacement procedures and by over 400% ($2392 to $12651) for total hip replacement procedures.  These wide variances could not be explained by differences in patient characteristics. The ratio of device cost to total surgical cost for knee and hip arthroplasty can be as high as 87%, with the median ratio being 43%.

The authors point out that data are currently lacking to support the belief that higher cost devices are associated with better outcomes. This is an important article, especially when viewed in the light of the survivorship of some of the more expensive and 'more modern' implants as also shown here. On this basis some have advocated device regulation to assure that new technology is optimally applied.

While we are not aware of similar data for shoulder implants, it is logical to assume that the same phenomenon exists there. We have also seen that the results with newer shoulder implants may not justify the associated expense. Determination of differences in outcome may require quite long term followup.

An interesting commentary on this article was offered: Joint Replacement Costs in the Era of Healthcare Reform: Commentary on an article by James C. Robinson, PhD, MPH, et al.: “Variability in Costs Associated with Total Hip and Knee Replacement Implants” The author of this commentary reminded that orthopaedic implants and procedures are major contributors to the rising cost of healthcare. In spite of the rising number of these procedures performed each year, the cost of these procedures is not following 'economies of scale principles' in which the implant cost per case would drop as the number of cases increased. The author of the commentary suggests several possible approaches to reducing these costs: (1) collective bargaining by Medicare with the implant manufacturers, (2) defining standards on the impact of new devices on cost and outcomes before they come to market, opining that 'there is little evidence that newer and more expensive devices are associated with better functional outcomes', (3) lack of  'gain-sharing' between medical centers and surgeons, which could incentivize surgeons to cut costs without compromising outcomes, and (4) lack of a national joint registry, such as those that exist in other countries, that would provide cost and outcomes data that could inform future decisions on implant selection for particular categories of patients.

The bottom line is that in future we need to pay more attention to the value equation: how much better are the documented results with the new implant divided by how much more it costs than the existing device? If a country wanted to curb the rising cost of joint arthroplasty, would it be better for it to reduce the cost of implants or to reduce the payments to the surgeons implanting them? That choice may be on us sooner rather than later.

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Shoulder arthroplasty lessons from Twelve-Year Risk of Revision After Primary Total Hip Replacement in the U.S. Medicare Population JBJS

Twelve-Year Risk of Revision After Primary Total Hip Replacement in the U.S. Medicare Population was just published by JBJS.

As we've seen from previous posts, rate of revision is revision is a distinct outcome measure that is often applied in population based studies, such as registries and, as here, in data bases such as that from Medicare. This article may provide some suggestions regarding reducing the rate of revision in total shoulder arthroplasty. 

Their methods are of interest in that in this retrospective Medicare cohort study of total hip replacements for osteoarthritis performed between 1995 and1996 they determined the per year risk of revision and death. This is important because many studies report the 'revision rate' (revisions/procedures) without normalizing the result to how long after the index procedure the revision was performed. Thus one study with an average followup of 5 years may have a revision rate of 2.5% while another with an average folow-up of 10 years may have a revision rate of 5%. The per year risk of revision is the same for each of these studies.

The authors found that the risk of revision total hip replacement for patients remaining alive was approximately 2% per year for the first eighteen months and then 1% per year afterwards. As we've pointed out in two recent posts here and here, the per year revision rate for total shoulders in studies of national registries is much higher for total shoulders than what is reported here for total hips.

Using multivariate Cox proportional hazard models, the relative risk of revision was 1.2 times higher in men than in women and 1.5 times higher in patients sixty-five to seventy-five years of age at the time of primary total hip replacement than in those over seventy-five years. 

Patients of surgeons who performed fewer than six total hip replacements annually in the Medicare population had a higher risk of revision than those whose surgeons performed more than twelve per year (HR, 1.21; 95% CI, 1.12, 1.32). The effect of surgeon volume on the quality of the result of shoulder arthroplasty has been posted before in this blog.  It is of more than philosophical interest to determine the number of cases per year needed to keep a surgeon on top of the factors contributing to the outcome of joint arthroplasty.

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Comparison of Ten-Year Survivorship of Hip Prostheses with Use of Conventional Polyethylene, Metal-on-Metal, or Ceramic-on-Ceramic Bearings JBJS

What does "Comparison of Ten-Year Survivorship of Hip Prostheses with Use of Conventional Polyethylene, Metal-on-Metal, or Ceramic-on-Ceramic Bearings" have to do with total shoulders?

High complements go to the authors from the Valdoltra Orthopaedic Hospital in Ankaran, Slovenia for their long term followup of 487 hips in 469 patients.

This is a most interesting article in that it shows (1) long-term followup is critical for the assessment of the results of joint arthroplasty and (2) "new" is not necessarily better.  As we saw in an earlier post, a large Australian registry showed that some of the newer shoulder arthroplasty designs had higher revision rates than their predecessors. In this article about total hips, the survivorship was determined as the time to revision for any reason.  The authors found that the newer ceramic on ceramic (CoC) bearing surface systems did not outperform conventional metal on polyethylene (MoP). The newer metal on metal (MoM) bearing surfaces had significantly worse survivorship than conventional metal on polyethylene. Their results are nicely summarized in their figure below showing survivorship by year.

Of great importance in this figure is the fact that had the study been concluded at 6 years of followup, it is doubtful than any difference would have been noted. Patients expect long term performance, we need to provide long term followup.

The other important point is that lots of money is spent on developing newer prostheses, for the hip, knee and shoulder - money on research, development, FDA approval, marketing, consultancy and royalties. Imagine what the total figures might be for MoM or CoC hips. These monies are recovered from patients and their insurances. We need to keep a close eye on the value (benefit/cost) of innovation so that health care dollars are spent wisely. New designs bring new risks. CoC bearings introduce the risk of ceramic fracture. MoM bearings introduce the risk of metal debris and increased serum ion levels. 

These authors found a survivorship of 0.984 at ten years for conventional MoP bearings. New designs have to be pretty spectacular to surpass that.

In total shoulder arthroplasty, the principal cause of failure is the glenoid component, yet most 'new' generations of arthroplasty represent changes in the design and increased complexity of the humeral component. It is time to refocus efforts on where the problem lies and to put innovation to the test of long term followup as our colleagues in Slovenia have done for hip arthroplasty.

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