Surgical Procedures Needed to Eradicate Infection in Knee Septic Arthritis

Surgical Procedures Needed to Eradicate Infection in Knee Septic Arthritis Omkar H. Dave, MD; Karan A. Patel, BS; Clark R. Andersen, MS; Kelly D. Carmichael, MD abstract Septic arthritis of the knee is encountered on a regular basis by orthopedists and nonorthopedists. No established therapeutic algorithm exists for septic arthritis of the knee, and there is much variability in management. This study assessed the number of surgical procedures, arthroscopic or open, required to eradicate infection. The study was a retrospective analysis of 79 patients who were treated for septic knee arthritis from 1995 to 2011. Patients who were included in the study had native septic knee arthritis that had resolved with treatment consisting of irrigation and debridement, either open or arthroscopic. Logistic regression analysis was used to explore the relation between the interval between onset of symptoms and index surgery and the use of arthroscopy and the need for multiple procedures. Fifty-two patients met the inclusion criteria, and 53% were male, with average follow-up of 7.2 years (range, 1-16.2 years). Arthroscopic irrigation and debridement was performed in 70% of cases. On average, successful treatment required 1.3 procedures (SD, 0.6; range, 1-4 procedures). A significant relation (P=.012) was found between time from presentation to surgery and the need for multiple procedures. With arthroscopic irrigation and debridement, most patients with septic knee arthritis require only 1 surgical procedure to eradicate infection. The need for multiple procedures increases with time from onset of symptoms to surgery. [Orthopedics] Septic arthritis of the knee is encountered by orthopedists and other physicians, among them practitioners in primary care, rheumatology, and emergency medicine. 1-4 Septic arthritis is among the few true orthopedic emergencies. 5 Although Staphylococcus aureus is the most frequently encountered causative organism, a multitude of other organisms have been reported. 4,6-14 There is no validated algorithm for the treatment of septic knee arthritis. Whether irrigation and debridement should be arthroscopic or open is a matter of controversy. 4,15-21 Balabaud et al 22 and Kuo et al 23 showed that a delay between the onset of symptoms and surgery was the major prognostic factor for outcome. The goal of this retrospective study was to determine the number of procedures, whether arthroscopic or open, required to cure septic knee arthritis. Additionally, the authors explored the effect of delay in surgical treatment on the need for multiple procedures. Materials and Methods The study was approved by the authors institutional review board. The authors reviewed the medical records of all patients treated at their institution between July 1995 and May 2011 with International Classification of Diseases, Ninth Revision, codes 711.00 (pyogenic arthritis, site unspecified), 711.06 (pyogenic arthritis, low leg), 711.09 (pyogenic arthritis, multiple sites), 711.40 (arthropathy with The authors are from the Department of Orthopaedic Surgery and Rehabilitation, The University of Texas Medical Branch, Galveston, Texas. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Kelly D. Carmichael, MD, Department of Orthopaedic Surgery and Rehabilitation, The University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555 (kdcarmic@utmb.edu). Received: December 14, 2014; Accepted: June 8, 2015. doi: 10.3928/01477447-20151222-05 1

bacterial disease, site unspecified), 711.46 (arthropathy with bacterial disease, low leg), 711.90 (unspecified infective arthritis, site unspecified), or 711.96 (unspecified infective arthritis, low leg). The study included patients who had unilateral septic arthritis of a native knee that was treated with arthroscopic or open irrigation and debridement and was completely resolved. Patients who held prisoner status or who had total knee arthroplasty, those who had a fracture about the knee that was treated with or without retained hardware, and those who were currently undergoing treatment for unresolved septic knee arthritis were excluded. Clinical presentation data were reviewed. Demographic data collected included patient age, sex, body mass index, and knee laterality. Routine serum laboratory values included leukocyte count, erythrocyte sedimentation rate, and C- reactive protein concentration. Joint aspirate leukocyte count and final cultures were noted. Also reviewed were current smoking status and history of intravenous drug use. Additionally, the authors recorded the type and number of surgical procedures performed, the date of the index procedure, the time from onset of symptoms to presentation, the time from onset of symptoms to index procedure, the time from presentation to index procedure, the time from presentation to the start of intravenous antibiotics, the duration of intravenous antibiotic administration, and total hospital stay. Presentation was defined as either the time of arrival at the emergency room or clinic or the time of inpatient orthopedic consultation. Diagnosis and Rationale for the Type of Procedure A clinical diagnosis of septic arthritis was made based on history and physical examination, with laboratory findings and joint fluid analysis used as adjuncts. Hallmarks included diffuse, progressively worsening knee pain, swelling, and erythema; reluctance to bear weight; and pain on passive and active range of motion. Other routine findings, although not always present, were fever, serum leukocytosis, and elevated erythrocyte sedimentation rate and C-reactive protein concentration. Most patients underwent arthrocentesis performed by either an emergency medicine attending physician or an orthopedic surgery resident. The aspirate was sent immediately for Gram stain and aerobic, anaerobic, acid-fast bacillus, and fungal cultures as well as analysis of crystals and leukocyte cell count. Although indicators of infection included a positive finding on Gram stain, a leukocyte cell count of greater than 50,000 cells/ml, and positive culture findings, the diagnosis and the decision to operate were based more on the primary clinical impression than on laboratory findings. The decision to use an arthroscopic or open technique was based on surgeon preference. Arthroscopic and Open Techniques For arthroscopy, standard inferomedial and inferolateral working portals were made. An accessory superomedial portal was also used on occasion. A 30 angled arthroscope was used to perform a diagnostic examination. Thorough lavage was performed with a minimum of 6 L lactated Ringer solution. For the open technique, a midline incision was used and taken down to the level of the capsule. A medial parapatellar arthrotomy was made. If a more thorough approach was needed, an additional small lateral arthrotomy was used. The joint was washed with a minimum of 6 L lactated Ringer solution. For both arthroscopic and open procedures, varying degrees of synovectomy were performed as necessary. The spectrum ranged from lavage with no synovectomy to extensive subtotal synovectomy. Although patients with significant effusion, fever, and prolonged preoperative symptoms were considered for synovectomy, the decision was made according to surgeon preference. For open and arthroscopic procedures, all incisions were closed completely, and no drains were used. Postoperatively, no restrictions on weight bearing or range of motion were made. Aggressive early range of motion was routinely emphasized. Statistical Analysis Logistic regression analysis was used to explore the relation between the interval between onset of symptoms and index surgery and the use of arthroscopy and the need for multiple procedures. A 95% confidence level was used. Results Among the 52 patients analyzed, average follow-up was 7.2 years (range, 1-16.2 years). Of the 52 patients, 28 were male (54%). The right knee was involved in 24 patients (46%). Average age was 43.4 years (SD, 23.8; range, 0.8-82 years), and mean body mass index was 27 kg/m 2 (SD, 8.7; range, 16-70.4 kg/m 2 ). Only 1 patient had a history of intravenous drug use, and 9 patients were current smokers (17%). A summary of the results from the material sent for culture is shown in Table 1. Average serum leukocyte count, erythrocyte sedimentation rate, and C-reactive protein concentration, respectively, were 12.9 10 9 cells/l (SD, 5.6; range, 4.5-35.8 cells/l); 67.4 mm/h (SD, 29.4; range, 21-120 mm/h); and 12.4 mg/l (SD, 9.3; range, 0.9-30.5 mg/l). Mean joint fluid white blood cell count was 955,010 cells/ ml (SD, 73,032.6; range, 440-355,000 cells/ml). Arthroscopic treatment alone was used in 36 cases (69%), and open treatment alone was used in 10 cases (19%). In 12 patients, multiple procedures were required for successful treatment (23%). In patients requiring multiple surgeries, 4 underwent open treatment after initial arthroscopic treatment (7.7%) and 1 underwent arthroscopic treatment after initial open treatment. Multiple arthroscopiconly and open-only procedures were needed in 4 patients (7.7%) and 3 patients (5.8%), respectively. 2 Copyright SLACK Incorporated

On average, successful treatment to eradicate infection required 1.3 procedures (SD, 0.6; range, 1-4 procedures). Time courses of treatment are shown in Table 2. Mean interval between presentation and the index procedure was 24.3 hours overall, 15.4 hours in patients requiring a single procedure, and 47.8 hours in those requiring multiple procedures (13 patients; 25%). In the logistic regression analysis of the relation between the interval between onset of symptoms and index surgery and the use of arthroscopy and the need for multiple procedures, the duration was log-transformed to better approximate a normal distribution. A statistically significant relation was found between the log of the number of hours between onset of symptoms and the index procedure (P=.012) and the need for multiple procedures, with a 1-unit increase in the log of the time (in hours) between presentation to surgery yielding a 4.2 times (95% confidence interval, 1.4-13.1) increase in the odds of requiring multiple procedures to resolve the infection. No significant relation was found between the use of arthroscopy and the need for multiple procedures (P=.33). Discussion Septic arthritis of the knee is a common orthopedic emergency that carries high rates of morbidity and mortality. 24 Shirtliff and Mader, 24 in a 2002 review, found that delayed and/or inadequate treatment caused permanent impairment of joint movement in 10% to 73% of patients with nongonococcal septic arthritis and had a mortality rate of 5% to 20%. The knee is the most commonly affected articulation in adults, and in children it is the second most common, after the hip. 9 No treatment algorithm for septic arthritis of the knee has been established. Consequently, there is much variability in management. The current cohort consisted of pediatric through geriatric patients. As seen in Table 1, S aureus was the most commonly Organism isolated organism, but many other organisms were cultured. In more than one third of patients, however, no organisms grew. This finding is in keeping with other studies of septic arthritis that showed a prevalence of no growth on culture of 0% to 40%. 9 Recently, there has been a shift toward the use of arthroscopic irrigation and debridement. However, open arthrotomy is still successfully used at many institutions. Successful treatment requires Table 1 Final Culture Results in Patients With Septic Knee Arthritis No. (%) of Patients Staphylococcus aureus 15 (28.85) Methicillin-resistant S aureus 5 (9.62) Group B streptococcus 5 (9.62) Pseudomonas 1 (1.92) Candida albicans 1 (1.92) Proteus mirabilis 1 (1.92) Coagulase-negative staphylococcus 1 (1.92) Group C streptococcus 1 (1.92) Diphtheroids 1 (1.92) Multiple (methicillin-resistant S aureus and Pseudomonas) 1 (1.92) No organisms 20 (38.46) Total 52 (100) Table 2 Time Course of Treatment for Patients With Septic Knee Arthritis Treatment Mean±SD Time, h Symptom onset to presentation 76.7±56.7 Presentation to intravenous antibiotic administration 10.2±10.5 Duration of intravenous antibiotic therapy 14.9±13.4 Symptom onset to index procedure 101.4±81.9 Single procedure 83.3 Multiple procedures 160.9 Presentation to index procedure 24.3±43.8 Single procedure 15.4 Multiple procedures 47.8 Length of hospital stay 10.9±9 prompt diagnosis and treatment, joint decompression to reduce pressure on the articular cartilage, joint lavage to clear enzymatically active and necrotic material, appropriate intravenous and oral antibiotic therapy, and early rehabilitation. 25 Advantages of arthroscopic treatment over traditional open methods include efficient joint decompression and irrigation of purulence from the joint, a decreased contribution to postoperative arthrofibrosis and motion limitations, and thorough joint 3

assessment, with a minimum of operative morbidity. 26,27 At the authors institution, during the years studied, arthroscopic irrigation and debridement was more commonly used than an open procedure for septic arthritis of the knee. Most patients treated over the span of this study initially underwent arthroscopic treatment, and most were treated successfully with arthroscopy alone. In a series of 20 patients, Yanmis et al 28 reported that treatment of infection with 1 session of arthroscopic debridement and irrigation was successful in 95% of cases. The current series found a similarly high success rate (75%) after only 1 surgical session. Key differences between the studies are the inclusion of a greater number of patients in the current study treated with both open and arthroscopic methods and the use of a postoperative continuous irrigation-drainage system in the study by Yanmis et al. 28 Prompt articular lavage of the septic knee is of utmost importance. In a study of 30 patients, most of whom received early treatment during a 72-hour interval, Smith 29 reported no recurrences or failures. Many studies have reported that the time between initial symptoms and operative treatment is an important predictor of eradication of infection and clinical outcome. 21-23,28 Wirtz et al 21 reported better results when there was an interval of no more than 12 days between initial symptoms and surgery. Yanmis et al 28 and Balabaud et al 22 reported successful treatment in patients with an average of 4 days and 15 days, respectively, between onset of symptoms and surgery. With an average of 4.2 days between initial symptoms and surgery, the current study corroborates the results of these studies. In a series of 40 patients, Balabaud et al 22 reported that a delay between the onset of symptoms and the index procedure was the major factor predicting success. The current results, by means of logistic regression, were in agreement with these findings. This study showed, with statistical significance (P=.012), that as the time to operative treatment increased, the likelihood of requiring more than 1 procedure for successful treatment also increased. However, no significant relation was found between the use of arthroscopy and the need for multiple procedures. Limitations One limitation of this study was its retrospective and nonrandomized design, although the authors analyzed a larger cohort of patients than similar studies. Additionally, this study did not report the severity of synovial involvement. This is routinely described by the Gächter classification, which is related to functional outcomes. 28 Finally, the current patients received varied degrees of synovectomy. However, there is no consensus on the indications for primary synovectomy in the literature, and synovectomy may be helpful only in patients with Gächter stage III and IV disease in which significant synovial hypertrophy is present. 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