1 Introduction

Acute septic arthritis of the native knee (ASANK) can lead to debilitating destruction of the articular cartilage, and if not treated expeditiously it can be fatal in up to 15% of the cases.^1–6 The incidence of septic arthritis is reported between 2 and 10 per 100,000 people and studies have described that this incidence could be higher in high-risk patients such as the elderly, patients with rheumatoid arthritis, patients with previous joint surgery, and patients with diabetes.⁷ There are also some reports describing that the frequency may be increasing due to the rising number of intra-articular interventions being offered (i.e. steroid injections and arthroscopic procedures).^1,8

The treatment of septic arthritis universally includes antibiotics and some type of joint drainage; however, the best method for irrigating and draining the joint has not been well defined. Serial aspiration and open arthrotomy have long been used to treat ASANK, and have undergone many improvements since the first ones described in 1896.⁹ Urgent open or arthroscopic surgery is now more commonly utilized for definitive treatment. Multiple studies in more recent years have been performed to validate the use of the less invasive arthroscopic surgery for the treatment of septic joints.^10–17 However, these studies have all been retrospective in nature, often involve different joints, and comprise small or medium sized cohorts. In 2011, Butt et al. surveyed rheumatologists and orthopaedic surgeons in the United Kingdom and revealed controversy in management of this condition secondary to a lack of evidence available for decision-making. They described that only 77% of rheumatologists and 66% of orthopaedic surgeons recommended joint drainage, while 22% and 27%, respectively recommended serial aspiration and not true surgical irrigation.¹⁸ In order to make the further advancements in treating ASANK, it should be determined which means of draining the knee leads to the best outcomes.

Due to the previously described lack of evidence, the purpose of this study is to determine the preferences of academic orthopaedic surgeons in regards to the proper treatment for septic arthritis of the knee. More specifically, we attempted to determine: (1) the preferred surgical technique, (2) the believed “gold standard” treatment, (3) the host factors that have the most influence on the technique chosen, and (4) the preferred treatment option for managing synovial tissue. We hypothesized that there will not be a consensus on the treatment utilized septic knee drainage. We also hypothesize that there will be great variation between the treatment that is considered the gold standard for ASANK.

2 Materials and methods

After obtaining Institutional Review Board (IRB) approval, a survey was electronically distributed to all American Council for Graduate Medical Education (ACGME) accredited orthopaedic residency programs in the US. This survey consisted of twelve questions and was administered using commercially available online software (SurveyMonkey™, San Mateo, California, US). The inclusion criteria were all orthopaedic faculty performing surgical procedures within the described programs. Basic-science faculty, residents, fellows, and non-operative orthopaedic faculty were excluded from participation.

Each program was contacted with an initial invitation to participate in the survey via email to the residency program coordinator. One hundred and fifty-six US ACGME accredited orthopaedic residency programs were contacted to participate in the survey. A subsequent reminder email was sent to encourage participation. Following obtaining consent for participation and certification that the respondent was an operative orthopaedic surgeon, all respondents were asked to identify their residency affiliation, what (if any) subspecialty fellowship training they had received, and how often they use arthroscopy as part of their clinical practice. All responses were anonymous throughout.

The participants were provided a clinical vignette of a 40-year-old, otherwise healthy male presenting with 3 days of fever, increasing knee pain, and serum and synovial labs consistent with septic arthritis of the knee. They were asked to give their treatment of choice, either open arthrotomy, arthroscopic irrigation, or serial aspiration. Following this clinical scenario, the participants were asked what they believe to be the “gold standard” for treatment of this condition. Other questions explored the surgeons’ preferred extent of synovectomy when performing open or arthroscopic irrigation. Respondents were also asked to rate how much influence various factors have on their surgical decision making using a numerical scale that ranges from 0 to 4 (No Influence = 0, Mild Influence = 1, Moderate Influence = 2, Heavy Influence = 3, and Extreme Influence = 4). To conclude the survey, surgeons were asked if they would be willing to participate in a prospective, randomized study investigating the two surgical techniques. If they would not be willing to participate in such a study, they were asked to explain why.

A total of 274 responses were obtained from 62 different academic institutions in the US (39.7% of all programs). Fig. 1 demonstrates the location of national responses by state. All data was collected and analyzed using the online software provided by the commercial survey administration company.

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Fig. 1 This map demonstrates the distribution of national responses received. The map is color coded to display the preference for surgical treatment of a native septic knee. Fig. 1 demonstrates how the responses varied by state, and further shows how the majority believed arthroscopy was the best surgical option for the patient in the vignette. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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3 Results

The preferred method of surgical treatment for ASANK among the orthopaedic surgeons in this survey was arthroscopy (69.8%), while 29.0% said that they would perform open arthrotomy, and only 1.2% described that serial aspirations was the best surgical treatment (Fig. 1.). In contrast, when asked about their thoughts for the gold standard treatment, 27.0% stated that arthroscopy is the gold standard and 29.4% stated that open arthrotomy is the gold standard; 43.6% stated that they do not think a gold standard exists, further emphasizing the current ambiguity on this topic.

Of those evaluated, the factor that had the most influence on surgeons when deciding on the technique to employ was patient medical-comorbidities with a weighted influence of 1.61. Trainee preference and the degree of pre-existing arthritis had very minimal influence (0.70 and 0.80 respectively). The relative influence of multiple factors in deciding surgical technique are detailed in Fig. 2.

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Fig. 2 This figure demonstrates the treatment of choice for a native septic knee in an adult based on subspecialty training.

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We separated the question regarding the extent of synovectomy performed during the operative management of ASANK into two groups, the arthroscopic group and the open arthrotomy group. Among the arthroscopic group, 9.1% elected irrigation alone, 35.2% irrigation with removal of devitalized tissue, 38.8% irrigation with shaving of inflamed synovial surfaces, and 16.9% felt that excision of all accessible synovium is a necessity. Amongst surgeons performing open arthrotomy, 5.0% elected irrigation alone, 40.5% elected a limited synovectomy of only devitalized appearing tissue, 22.5% irrigate and curette inflamed synovial surfaces, and 32.0% believe that all accessible synovium must be excised.

After stratifying by subspecialty we found that Sports and Shoulder & Elbow surgeons had the highest rates of choosing arthroscopy in the provided clinical vignette, while spine surgeons had the lowest rate of choosing arthroscopy (89.3% vs 40.0%, p = 0.0008). Surgeons without subspecialty training had a high rate of choosing arthroscopy (87.5%), as well as the highest rate of choosing arthroscopy as the gold standard (47.5%). Only 42.3% of those with Sports training and 20.8% of those with Shoulder & Elbow training felt that arthroscopy was the gold standard. Figs. 3 and 4 demonstrate the responses to the preferred treatment technique and the gold standard questions based on orthopaedic subspecialty training. More than half (58%) of the respondents answered that they would be willing to participate in a prospective study to address the question of discovering which surgical technique is superior in treating acute septic arthritis of the native knee.

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Fig. 3 This graph demonstrates what orthopaedic surgeons believe to be the gold standard of treatment for septic arthritis of a native adult knee based on subspecialty training. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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Fig. 4 Demonstration of relatively influence of multiple factors on surgical decision-making for technique of treatment for septic arthritis of a native knee. Influence was defined by the following scale: No Influence = 0, Mild Influence = 1, Moderate Influence = 2, Heavy Influence = 3, Extreme Influence = 4.

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4 Discussion

In the US, there has nearly unanimous agreement to treat septic arthritis of the knee with surgical debridement (98.8% of respondents choose this approach). Despite this, there was no other consensus on surgical strategy for the diagnosis. The results of this survey support our hypothesis that there is not a national consensus on the management of septic arthritis of the knee among academic orthopaedic surgeons in the US. While the majority of surgeons prefer arthroscopic treatment, most do not believe that arthroscopy is the gold standard.

The survey assessed several factors that potentially influence treatment decisions. The most influential factors according to this survey were patient comorbidities, duration of symptoms, and institutional limitations (1.61, 1.41, and 1.35 respectively). Even so, these factors did not reach an average of “Moderate Influence” on the weighted scale in this survey. None of these factors had a strong influence on surgical decision-making, implying that surgeons likely have their own biases towards the ideal treatment technique that may be largely predetermined. Without strong literature guidance, the surgical technique is likely directed by surgeon preference and experience.

One of the potential advantages of surgical treatment over serial aspirations is the ability to debride devitalized tissue and perform a synovectomy.^15,19 However, the role of synovectomy has not been studied or substantiated in the literature. The results of this survey show that the extent of synovectomy performed is highly variable, and there is no consensus on its necessity. Arthroscopic utilization for septic arthritis of the knee is certainly appealing as a minimally invasive treatment.^20,21 A recent study by Bohler et al. claimed that arthroscopy should be considered the ideal treatment for a septic knee as they described fewer persistent infections and better functional outcomes.²² However, arthroscopy can be challenging for the on-call orthopaedic surgeon, particularly with inexperienced staff in the middle of the night. Our study confirms that surgeons who are more comfortable with arthroscopy are more likely to choose arthroscopic treatment despite the potential challenges. There is a need for further research to substantiate the benefits of arthroscopic treatment of septic arthritis of the knee, and to evaluate the utility of synovectomy.

Despite the groundswell of support for arthroscopy, there were still slightly more surgeons in this survey who chose open arthrotomy as the gold standard rather than arthroscopy. Proponents of open arthrotomy believe it can better handle thick purulent loculations and intraarticular adhesions, and septic arthritis due to Staph Aureus or enteric gram negative rods may respond better to open arthrotomy.^23,24 Also, considering how technically challenging arthroscopy can be, open arthrotomy may be regarded as the gold standard to many surgeons until arthroscopic training and proficiency are better substantiated.²⁵

This study had several limitations. All conclusions obtained from surveys are potentially limited by an incomplete response rate. However, responses were obtained from a substantial number of programs and surgeons throughout the US. Additionally, the population surveyed may not be representative of a community-based practice, as the physicians surveyed are all affiliated with academic institutions. However, there is great diversity in residency programs across the US, and the respondents reflect the full spectrum of training backgrounds. In addition, surgeons in an academic practice may be more familiar with the latest evidence. Lastly, there may be other important factors in surgeon decision making that were not assessed in our survey; however, due to the time limitations of the respondents, we attempted to keep this survey as concise as possible.

The current strategy for treatment of septic arthritis in the US involves surgical irrigation and debridement.²⁶ The majority of orthopaedic surgeons prefer an arthroscopic treatment of a native septic-knee in an adult patient. However, there is no national consensus on a gold standard treatment or the role of synovectomy. Treatment choice is surgeon dependent and can be driven by fellowship-training experience and both patient-specific and institutional factors. Higher-level studies should be conducted to establish the optimal treatment for this common and potentially devastating condition.