Archive | Infection RSS for this section

Modern Irrigation/Debridement Yields Good Results for Early Post-THA Infection

Hip Debridement for OBuzzNowadays, chronic deep periprosthetic joint infections (PJIs) are typically treated with 2-stage exchange arthroplasty, but what about acute PJIs? In the December 6, 2017 edition of JBJS, Bryan et al. report on a retrospective cohort study of acute infections after hip arthroplasty. The results suggest we’ve come a long way in identifying patients with early infections and that contemporary irrigation-and-debridement protocols are more successful than older methods.

The researchers studied 6-year outcomes in 90 hips that had undergone either total or hemiarthroplasty and that were determined to have either acute early postoperative infections (n=66) or acute hematogenous infections (n=24). All the infected hips were managed with either irrigation, debridement, and modular head and liner exchange (70%) or with irrigation and debridement alone (30%). The authors stratified the patients into those without comorbidities (A), those with 1 or 2 comorbidities (B), and those with >2 comorbidities (C). Postoperatively, patients were treated with broad-spectrum intravenous antibiotics, followed by targeted therapy administered by infectious disease specialists.

Of the 90 acute infections, failure—defined as uneradicated infection, subsequent removal of any component for infection, unplanned second wound debridement for ongoing infection, or infection-related mortality—occurred in 15 hips (17%). Of those 15, 9 required component removal. The chances of treatment failure were slightly higher in cases of hematogenous infection (21%), compared with acute early postoperative infection (15%), but that difference was not statistically significant. Significant comorbidity-related failure-rate differences were found: failure occurred in 8% of the grade-A patients, 16% of grade-B patients, and 44% of grade-C patients. The most common infecting organism was methicillin-sensitive Staphylococcus aureus (MSSA).

From this overall 6-year success rate of 83%, the authors conclude that “with modern inclusion criteria for acute infection, modern surgical techniques, and modern antibiotic therapy…the rate of success was higher than in most historic reports.”

Fructosamine Bests HbA1c for Preop Glycemic Screening

Fructosamine for OBuzzPatients with diabetes have an increased risk of postoperative complications following total joint arthroplasty (TJA). Additionally, perioperative hyperglycemia has been identified as a common and independent risk factor for periprosthetic joint infection, even among patients without diabetes. Therefore, knowing a patient’s glycemic status prior to surgery is very helpful.

In the November 15, 2017 edition of The Journal of Bone & Joint Surgery, Shohat et al. demonstrate that serum fructosamine, a measure of glycemic control obtainable via a simple and inexpensive blood test, is a good predictor of adverse outcomes among TJA patients—whether or not they have diabetes.

Researchers screened 829 patients undergoing TJA for serum fructosamine and HbA1c—a common measure, levels of which <7% are typically considered good glycemic control. Patients with fructosamine levels ≥292 µmol/L had a significantly higher risk of postoperative deep infection, readmission, and reoperation, while HbA1c levels ≥7% showed no significant correlations with any of those three adverse outcomes. Among the 51 patients who had fructosamine levels ≥292 µmol/L, 39% did not have HbA1c levels ≥7%, and 35% did not have diabetes.

In addition to being more predictive of postsurgical complications than HbA1c, fructosamine is also a more practical measurement. A high HbA1c level during preop screening could mean postponing surgery for 2 to 3 months, while the patient waits to see whether HbA1c levels come down. Fructosamine levels, on the other hand, change within 14 to 21 days, so patients could be reassessed for glycemic control after only 2 or 3 weeks.

While conceding that the ≥292 µmol/L threshold for fructosamine suggested in this study should not be etched in stone, the authors conclude that “fructosamine could serve as the screening marker of choice” for presurgical glycemic assessment. However, because the study did not examine whether correcting fructosamine levels leads to reduced postoperative complications, a prospective clinical trial to answer that question is needed.

New Hope for New Bone After Osteomyelitis Debridement

Osteomyelitis Tibia for OBuzzThis basic science tip comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.

One clinical frustration following osteomyelitis debridement is poor bone healing. Impaired bone homeostasis provokes serious variations in bone remodeling that involve multiple inflammatory cytokines.

The chemokines CCL2, CCL3, and CXCL2 are known to be strong chemoattractants for neutrophils during inflammatory states, and they play a role during osteoclastogenesis. B cells are also activators of osteoclastognesis and are regulated, in part, by tissue inhibitor of metalloprotease 1 (TIMP-1).

Researchers drilled a 1 mm hole into the proximal tibia of 126 mice. In half of the mice (63), a dose of S. aureus was injected into the canal, while the controls had no bacteria injected. At two weeks, all proximal tibiae were debrided; cultures were taken 3 and 7 days after debridement to assure no residual infection. Cytokine assays and Western blots for CCL2, CCL3, CXCL2, TIMP-1, RANKL, and TNF-α were performed in selected mice in each group. Flow cytometry and histology were also done in selected mice in each group.

In the osteomyelitis group, Western blot analysis identified increased levels of CCL2, CCL3, and CXCL2. Histology revealed increased osteoclastogenesis after osteomyelitis debridement, with calcitonin-receptor and RANKL detection via immunohistochemical and fluorescence staining. There was diminished osteogenesis and proliferation in the osteomyelitis group, but TNF-α expression seemed to have no effect on altered bone regeneration after bone infection. Flow cytometry revealed elevated B cell activity in the osteomyelitis group, with subsequent increased osteoclast activity and accelerated bone resorption.

The researchers propose a RANKL-dependent osteoclastogenesis after debridement for osteomyelitis that is associated with elevated B cells and decreased osteogenesis. These findings could lead to new interventions to improve bone healing during the course of osteomyelitis treatment, particularly following debridement.

Reference
Wagner JM, Jaurich H, Wallner C, Abraham S, Becerikli M, Dadras M, Harati K, Duhan V, Khairnar V, Lehnhardt M, Behr B. Diminished bone regeneration after debridement of posttraumatic osteomyelitis is accompanied by altered cytokine levels, elevated B cell activity, and increased osteoclast activity. J Orthop Res. 2017 Mar 6. doi: 10.1002/jor.23555. [Epub ahead of print] PMID: 28263017

D-Dimer Levels May Help with PJI Diagnoses

D-dimer for OBuzzThe percentage of periprosthetic joint infections (PJIs) among patients requiring revision arthroplasty of the hip and knee is increasing. PJIs have important clinical implications both for revision surgical procedures as well as pre- and postoperative management. Any extra help we can get making a PJI diagnosis outside of the obvious (where the patient presents with a draining wound) would be most welcome.

In the September 6, 2017 issue of The Journal, Shahi et al. present compelling data from a prospective study suggesting that serum D-dimer levels may help diagnose PJI—and thereby help determine the optimal timing of component reimplantation. The authors determined that 850 ng/mL was the optimal threshold value for D-dimer in diagnosing PJI. Moreover, with sensitivity of 89% and specificity of 93%, this test outperformed the widely used ESR and CRP tests, which until now have proven to be the “best” tools we have at our disposal.

Ideally, after these results are confirmed in larger populations of patients undergoing revision arthroplasty, the serum D-dimer test—inexpensive and almost universally available—will be used in all high-volume joint replacement centers. The continued pursuit of diagnostic and treatment methodologies for patients with suspected PJI is definitely warranted, given the increasing number of patients requiring arthroplasty and combined lifetime knee- and hip-replacement revision rates hovering around 10% to 12%. The identification of D-Dimer elevation as a potentially more accurate diagnostic tool than our currently available tests is a welcome contribution.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

What’s New in Musculoskeletal Infection

PPI Image for O'BuzzEvery month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.

This month, Arvind Nana, MD, co-author of the July 19, 2017 Specialty Update on musculoskeletal infection, selected the five most compelling findings from among the more than 120 studies cited in the Specialty Update.

Periprosthetic Joint Infection

–Much of the discussion around treating periprosthetic joint infections (PJIs) centers around comparing one-stage versus two-stage exchange arthroplasty. Two-stage exchange arthroplasty requires the use of a temporary cement spacer, and one study1 found that debris from articulating spacers may induce CD3, CD20, CD11(c), and IL-17 changes, raising the possibility of associated immune modulation.

–When performing debridement to treat a PJI, instead of an irrigation solution containing antibiotics, a 20-minute antiseptic soak with 0.19% vol/vol acetic acid reduced the risk of reinfection.2

Spine

–Four studies helped bolster evidence that surgical-site infections are the leading cause of reoperations after spine surgery, both early (within 30 days)3, 4 and late (after 2 years).5, 6

Trauma

–A 100-patient prospective cohort study found that posttraumatic osteomyelitis treated with a 1-stage protocol and host optimization in Type B hosts resulted in 96% infection-free outcomes.7

Shoulder

–As in lower-extremity procedures, the risk of infection after shoulder arthroplasty and arthroscopy is higher when the surgeries are performed less than 3 months after a corticosteroid injection. This finding suggests elective shoulder procedures should be delayed for at least 90 days after such injections.8

References

  1. Singh G, Deutloff N, Maertens N, Meyer H, Awiszus F, Feuerstein B, Roessner A, Lohmann CH. Articulating polymethylmethacrylate (PMMA) spacers may have an immunomodulating effect on synovial tissue. Bone Joint J. 2016 ;98-B(8):1062–8.
  2. Williams RL, Ayre WN, Khan WS, Mehta A, Morgan-Jones R. Acetic acid as part of a debridement protocol during revision total knee arthroplasty. J Arthroplasty. 2017 ;32(3):953–7. Epub 2016 Sep 28.
  3. Medvedev G, Wang C, Cyriac M, Amdur R, O’Brien J. Complications, readmissions, and reoperations in posterior cervical fusion. Spine (Phila Pa 1976). 2016 ;41(19):1477–83.
  4. Hijas-Gómez AI, Egea-Gámez RM, Martínez-Martín J, González-Díaz RC, Losada-Viñas JI, Rodríguez-Caravaca G. Surgical wound infection rates and risk factors in spinal fusion in a university teaching hospital in Madrid, Spain. Spine. November 2016.
  5. Ohya J, Chikuda H, Takeshi O, Kato S, Matsui H, Horiguchi H, Tanaka S, Yasunaga H. Seasonal variations in the risk of reoperation for surgical site infection following elective spinal fusion surgery: a retrospective study using the Japanese diagnosis procedure combination database. Spine (Phila Pa 1976). 2016 . Epub 2016 Nov 22.
  6. Ahmed SI, Bastrom TP, Yaszay B, Newton PO; Harms Study Group. 5-year reoperation risk and causes for revision after idiopathic scoliosis surgery. Spine (Phila Pa 1976). 2016 . Epub 2016 Nov 9.
  7. McNally MA, Ferguson JY, Lau ACK, Diefenbeck M, Scarborough M, Ramsden AJ, Atkins BL. Single-stage treatment of chronic osteomyelitis with a new absorbable, gentamicin-loaded, calcium sulphate/hydroxyapatite biocomposite: a prospective series of 100 cases. Bone Joint J. 2016 ;98-B(9):1289–96.
  8. Werner BC, Cancienne JM, Burrus MT, Griffin JW, Gwathmey FW, Brockmeier SF. The timing of elective shoulder surgery after shoulder injection affects postoperative infection risk in Medicare patients. J Shoulder Elbow Surg. 2016 ;25(3):390–7. Epub 2015 Nov 30.

JBJS Editor’s Choice—Knee Sepsis: Arthroscopic or Open Treatment?

Open vs Arthroscopic Tx for Knee Sepsis.jpegIn the March 15, 2017 issue of The Journal, Johns et al. report results from a Level III cohort study comparing arthroscopic vs open irrigation for control of acute native-knee sepsis. The authors collected information on more than 160 patients with knee sepsis over a 15-year period, which is a large cohort of patients with this relatively unusual clinical problem.

The data show a cumulative success rate of 97% with arthroscopic treatment after 3 irrigations and debridements vs 83% success in the arthrotomy group after the same number of procedures—a clinically important difference. Significantly fewer arthroscopic procedures were required for successful treatment, relative to open procedures, and post-procedure median knee range of motion was significantly greater in the arthroscopic group (90°) than in the open treatment group (70°).

The fact is that arthroscopic instruments allow a greater volume of irrigation fluid to be instilled with better access to the posterior recesses of the knee. With an open arthrotomy, it is more difficult to irrigate with high volumes, and the posterior recesses of the knee are not well accessed. It seems clear that arthroscopic management of acute knee sepsis should be the standard of care for these reasons, as well as because the technique is minimally invasive in terms of soft tissue stripping and incision size.

Treating infections of major-weight bearing joints is following a trend seen in surgical management of many orthopaedic conditions—smaller exposures with use of adjunctive visualization techniques.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Smoking Boosts Rate of Reoperation for Infection after TJA

Smoking Image from Nick.jpegHere’s one thing about which medical studies have been nearly unanimous:  Smoking is a health hazard by any measure. In the February 15, 2017 edition of The Journal of Bone & Joint Surgery, Tischler et al. put some hard numbers on the risk of smoking for those undergoing total joint arthroplasty (TJA).

After controlling for confounding factors, the authors of the Level III prognostic study found that:

  • Current smokers have a significantly increased risk of reoperation for infection within 90 days of TJA compared with nonsmokers.
  • The amount one has smoked, regardless of current smoking status, significantly contributed to increased risk of unplanned nonoperative readmission.

In a commentary on the Tischler et al. study, William, G. Hamilton, MD says, “…as physicians, we should work cooperatively with our patients to enhance outcomes by attempting to reduce these modifiable risk factors. We can educate patients and can suggest smoking cessation programs and weight loss regimens that may not only improve the risk profile during the surgical episode, but also improve the patients’ overall health.”

JBJS Reviews Editor’s Choice–Sport-Related SSTIs

SSTI.pngI may never go to the gym again!

In the January 2017 issue of JBJS Reviews, Mitchell et al. report on sport-related skin and soft tissue infections (SSTIs) as an ongoing problem across a diverse range of recreational, collegiate, and professional athletes. They note that these infections often occur during training for competitive sports or during the competition and that the majority are bacterial or fungal in origin. The review describes the mechanisms by which SSTIs occur in healthy athletes and the prevalence among players in various sports, including the effect of player position. The authors discuss the mechanisms by which SSTIs are spread and the hygiene measures that are recommended to prevent their spread. They extrapolate these lessons to the general population of so-called weekend warriors or fitness enthusiasts. This is what worries people like me, as studies have shown that these infections easily occur during regular visits to fitness centers and gymnasiums, which are sources of large quantities of bacteria that could cause SSTIs!

Studies have shown that billions of bacteria, fungi, and other microbes inhabit the skin and that the types of organisms vary between individuals and between different sites of the skin. In fact, they may vary in relation to each region of the body. Indeed, factors such as skin characteristics, sebaceous gland concentration, moisture content, temperature, and genetics as well as exogenous environmental factors can influence each so-called community of organisms. The authors hypothesize that sports in which participants have substantial skin-to-skin collisions might disrupt these ecosystems on the skin and allow microbes to be shared among players, noting that contact athletes have been shown to be potential carriers of methicillin-resistant Staphylococcus aureus (MRSA) more than twice as frequently as athletes who participate in noncontact sports. Other mechanisms by which SSTIs occur in healthy athletes include maceration of the skin due to sweating as well as strenuous training. Of particular interest is the observation that extended periods of intense exercise may temporarily depress certain aspects of the immune system, including natural killer cells, neutrophils, lymphocytes, immunoglobulin levels, and interleukin-2 levels and thus facilitate and promote infection and its potential host transfer.

The article goes on to explain how SSTIs are spread, the prevalence of SSTIs among players in various sports, the importance of personal and environmental hygiene, and specific forms of treatment of SSTIs in athletes.

When you do go to the gym or fitness center, just remember to clean off any equipment both before and after use and to change out of your workout clothes and shower as soon as possible after the workout. Be sure to cover benches with a towel, and if you practice yoga, bring your own mat.

I definitely will continue to use the gym but will pay more attention to the issues raised in this review.

Thomas A. Einhorn, MD
Editor, JBJS Reviews

Guest Post: Single-Stage Revision for Failed Shoulder Arthroplasty Is Effective

TSA Infection.gifOrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Grigory Gershkovich, MD.

Shoulder arthroplasty continues to grow in popularity, and as the number of shoulder arthroplasties rises, so will the number of revisions. Infection is one major reason for shoulder arthroplasty failure, and Propionibacterium has been increasingly recognized as a major culprit.

However, Propionibacterium infection is difficult to diagnose. Despite improved detection techniques, diagnosis at the time of revision remains elusive because obvious signs of acute infection are often absent. The need to perform explantation in the setting of clinically apparent periprosthetic infection is obvious, but the appropriateness of single-stage revision with antibiotic treatment in shoulders with only apparent mechanical failures remains questionable.

Hsu et al. attempted to address this question in a study published in the December 21, 2016 issue of JBJS. The group retrospectively reviewed the outcomes of 55 shoulders that underwent revision arthroplasty due to continued pain, stiffness, or component loosening without obvious clinical infection. Mean follow up was 48 months. At least five cultures were obtained intraoperatively during each revision, and each case was treated with antibiotics as if were truly infected until the final culture results were received after three weeks. Shoulders were revised to either hemi-arthroplasty, total shoulder arthroplasty, or reverse total shoulder arthroplasty.

Hsu et al. analyzed outcomes according to two groups: the positive cohort (n=27), where shoulders had ≥ 2 cultures positive for Propionibacterium, and the control cohort (n=28), where shoulders had either 0 or 1 positive culture. The two groups were compared by before- and after-revision performance on the simple shoulder test (SST) and pain outcome scores.

Both groups improved postoperatively based on these patient-reported outcome measures, and no significant difference was found between the two groups. Three patients in each group required a return to the OR. Gastrointestinal side effects were the most commonly reported complication from prolonged antibiotic administration.

This study design was limited by its retrospective nature and the lack of a two-stage revision treatment comparison group. Furthermore, this study included only patients with no signs of clinical infection, and the findings may not be applicable to patients with perioperative signs of infection. The study also incorporated three revision surgery implant options, which could have influenced postoperative SST and pain scores. Larger, multicenter controlled trials will be needed to produce a more definitive answer to this complicated question.

Still, there are clear benefits of single-stage revision over two-stage revision, especially with regard to operative time, anesthesia risks, and patient recovery. Given the wide antibiotic sensitivity profile of Propionibacterium and these initial results from Hsu et al., single-stage revision with appropriate antibiotic therapy may be suitable for patients undergoing revision shoulder arthroplasty in the setting of suspected Propionibacterium infection.

Grigory Gershkovich, MD is chief resident at Albert Einstein Medical Center in Philadelphia. He will complete a hand fellowship at the University of Chicago in 2017-2018.

No Surprise: Infection Biggest Culprit in Amputation for Failed TKA

Cumulative Amputations_12_7_16.gifOf the hundreds of thousands of total knee arthroplasties (TKAs) performed annually around the world, very few result in failure so irreparable that transfemoral amputation is the last resort. But what does “very few” really mean? In the December 7, 2016 issue of The Journal of Bone & Joint Surgery, Gottfriedsen et al. determine the cumulative incidence of amputation for failed TKAs among nearly 93,000 registered knee replacements performed in Denmark from 1997 to 2013.

The authors used a competing-risk model (which took into account the competing risk of death) to avoid overestimating incidence. From a total of 115 amputations performed for causes related to failed TKA, they calculated a cumulative 15-year incidence of amputation of 0.32%. They noted a tendency toward decreasing incidence during the 2008-2013 period, relative to the 1997-2002 period.

The three most common causes of post-TKA amputation were periprosthetic infection (83%), soft-tissue deficiency (23%), and severe bone loss (18%). The authors add, however, that the latter two causes are “most likely the result of long-term infection together with several revision procedures, in which soft tissue and bone stock are gradually damaged.”

The authors encourage orthopaedists to consider newer treatment options to avoid amputation (such as skin grafts and muscle flaps for soft-tissue loss), but they also assert that, in each individual case, those contemporary approaches should be balanced against the “psychological and physical strains related to repeated surgery performed in an attempt to salvage the knee.”