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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.”

Whence P. Acnes in Shoulder Arthroplasty?

p-acnes-pie-chartPropionibacterium acnes is a frequently isolated pathogen in postoperative shoulder infections, but where exactly does it come from? According to a study by Falconer et al. in the October 19, 2016 Journal of Bone & Joint Surgery, P. acnes derives from the subdermal edges of the surgical incision and spreads through contact with the surgeon’s gloves and surgical instruments.

The authors obtained specimens for microbiological analysis at five different sites from 40 patients undergoing primary shoulder arthroplasty. Thirty-three percent of the patients had at least one culture specimen positive for P. acnes, and the most common site of P. acnes growth was the subdermal layer, followed by forceps.

The authors observed no clinical postoperative infections during the follow-up of 6 to 18 months, although that is a relatively short investigation period for a pathogen that often causes late-onset indolent infections. The authors conclude that “it is likely that surgeon handling of the skin and subdermal layer contaminates the rest of the surgical field.” Although the study did not investigate preventive techniques, based on the findings the authors suggest the following possible prophylactic approaches:

  • Minimizing handling of the subdermal layer
  • Changing gloves after the dermis is cut
  • Avoiding contact between implants and the subdermal layer
  • Repeating use of antibacterial agents once the wound is opened

JBJS Reviews Editor’s Choice–Open Fracture Care During War

War Wound.jpgInjuries to the musculoskeletal system are among the most common wounds of war. Compared with extremity injuries in the civilian population, injuries sustained in combat tend to be due to high-energy explosions and are associated with a greater degree of contamination and a longer timeline for recovery and healing. Importantly, the sequelae of musculoskeletal injuries sustained during combat tend to lead to more long-term disability than those affecting other organ systems.

In this month’s Editor’s Choice article, Rivera et al. review the current literature on combat injuries of the lower extremity and suggest that explosions are the most common mechanism of injury encountered by deployed service members. While exposure to an explosion does not necessarily result in a specific limb injury, the explosion mechanism does contribute to more severe injuries. Moreover, among service members who sustain open fractures of the tibia, foot, and ankle, infection is a common complication and is associated with more severe soft-tissue injury. As a result, surgeons who are deployed in combat settings are now performing more fasciotomies for limbs that are at risk. However, the outcomes and complication rates associated with these procedures are not well established, and the causes of late amputations are not always clear.

As part of a comprehensive review of this topic, Rivera et al. pose 3 important clinical questions that are ideal for translational research investigation. First, they ask, “What is the best way to manage and transport patients who have severe open fractures in order to minimize infection?” Indeed, while negative-pressure wound therapy (NPWT) appears to be a promising wound-care technique, additional study is needed in order to know how to best augment the standard of care for battlefield medicine. Second, “What is the best way to treat fasciotomy wounds and the late sequelae of the compartment syndrome?” In order to answer this question, a broader understanding of compartment syndrome detection and the indications for surgical treatment are needed. Finally, “What is the best way to select limbs for salvage and to optimize the reconstruction of injured tissues?” This question must explore not only the patient’s perspective but also the multitude of causes that lead to late amputation.

Thomas A. Einhorn, MD
Editor, JBJS Reviews

JBJS Webinar: Effective Management of the Infected Total Joint

infected-knee-for-webinar-postThe incidence of primary total knee and hip arthroplasty is increasing steadily. While the success rates of these procedures are remarkable, failures do occur, and periprosthetic joint infection is the leading culprit in such failures. The standard treatment when deep infection strikes is a two-stage revision.

On Monday, November 14, 2016 at 8:00 PM EST, The Journal of Bone & Joint Surgery (JBJS) will host a complimentary webinar that examines prognostic factors affecting the success of two-stage revision arthroplasty for infected knees and hips.

  • Tad M. Mabry, MD, coauthor of a matched cohort study in JBJS, will examine the impact of morbid obesity on the failure of two-stage revision TKA.
  • JBJS author Antonia F. Chen, MD, will discuss results from a retrospective study that revealed an association between positive cultures at the time of knee/hip component reimplantation and the risk of subsequent treatment failure.

Moderated by JBJS Deputy Editor Charles R. Clark, MD, the webinar will include additional perspectives from two expert commentators—Daniel J. Berry, MD and Andrew A. Freiberg, MD. The last 15 minutes will be devoted to a live Q&A session, during which the audience can ask questions of all four panelists.

Seats are limited, so register now!