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Septic arthritis of the knee

87 citationsUpdated Sep 2026
Illustration: knee

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Overview

Septic arthritis of the adult knee is a surgical urgency [5]. Staphylococcus aureus remains the most common causative organism, although rates of methicillin-resistant S. aureus are increasing [5]. Intravenous drug use is an increasingly common cause of septic knee admissions and is associated with higher rates of mortality, reoperations, resource utilization, and leaving against medical advice [48].

Postoperative septic arthritis following ACL reconstruction is rare but carries high morbidity and results in poor clinical outcomes and protracted hospitalization [2, 6]. However, septic arthritis after ACL reconstruction did not result in inferior objective knee function compared with uncomplicated ACL reconstruction [3]. Persistence or recurrence of clinical signs of infection after management should raise suspicion of adjacent osteomyelitis, a concern particularly relevant in patients with comorbid conditions [1].

Patients with a history of treated septic arthritis are at high risk of developing periprosthetic joint infection after total joint arthroplasty [7]. This risk is greater in knee arthroplasty compared to hip arthroplasty for these patients [7]. In the knee, cases of unsuspected prosthetic joint infection had inferior infection-free survival at two years compared with those with negative cultures [9].

Anatomy & Pathophysiology

Osseous Anatomy

The knee joint comprises the distal femur, proximal tibia, and patella [42]. The medial femoral condyle is larger and projects farther posteriorly and distally than the lateral condyle [65]. The medial epicondyle is the most anterior and distal osseous prominence of the distal femur, with the adductor tubercle located proximal and posterior to it [65]. The gastrocnemius tubercle lies slightly distal and posterior to the adductor tubercle [65]. Conversely, the lateral femoral condyle projects farther anteriorly and is wider in the medial-lateral direction than the medial condyle [65, 70]. This broader anterior-posterior and medial-lateral dimension of the lateral condyle allows internal rotation of the distal femur with knee extension [70]. The sulcus terminalis is a small ridge on the lateral femoral condyle just distal to the intercondylar notch that separates the patellofemoral and tibiofemoral articular surfaces [65]. It is a transverse ridge extending from the oblique facets of the femoral trochlea, deeper on the lateral condyle than on the medial condyle [70]. The trochlear groove separates the condyles anteriorly and constitutes the patellofemoral articulation [65], while the lateral trochlear facet resists lateral subluxation of the patella [70]. The intercondylar notch is of variable width and serves as the attachment site for the cruciate ligaments [65].

The tibial articular surface slopes 7° to 10° in the sagittal plane [65], with a mean posterior slope of 10.7° in the medial plateau and 7.2° in the lateral plateau [70]. The medial tibial plateau is larger than the lateral plateau and is concave in both frontal and sagittal planes [65]. The lateral tibial plateau is smaller, more circular, concave in the frontal plane, and convex in the sagittal plane [65]. The medial compartment has a large surface area containing the convex femoral condyle and concave tibial plateau [70]. The lateral compartment has a smaller surface area and contains the convex femoral condyle and convex lateral plateau in the sagittal plane [70]. The medial and lateral tibial plateaus are separated by the intercondylar eminence and its medial and lateral spinous processes [65]. The tibial tuberosity, the attachment site of the patellar tendon, is typically located in the midline anteriorly but may be slightly lateral [65]. Gerdy’s tubercle, the insertion site of the iliotibial band, is located 2 to 3 cm lateral to the tibial tubercle on the proximal tibia [65]. The proximal fibula articulates with a facet of the lateral cortex of the tibia and is not part of the knee articulation [65]. The fibular head is located a mean of 1.5 cm distal to the joint line, with a range of 6 to 32 mm below the joint line [70].

The patella is the largest sesamoid bone in the body, averaging 2.5 cm in thickness [65]. It possesses the thickest articular surface in the body, approximately 5 mm in the midportion and 2 mm on the sides [65]. The patellar articular surface contains a vertical, central ridge that separates the broader lateral facet from the medial facet, along with a smaller, more medial facet called the odd facet [65]. The odd facet is a small facet on the distal medial patella that articulates in deep flexion of the knee [70].

Ligamentous Anatomy

The anterior cruciate ligament (ACL) travels from the medial border of the lateral femoral condyle to its insertion site anterolateral to the medial tibial spine [42]. It prevents anterior translation and rotation of the tibia on the femur [42]. The ACL is composed of 90% type I collagen and 10% type III collagen [65, 66]. Its mean length is 33 mm and mean midsubstance width is 11 mm [65], with another source citing a length of 30 mm and diameter of 11 mm [66]. The femoral attachment is a semicircular area (20 mm long and 10 mm wide) on the posteromedial aspect of the lateral femoral condyle [65, 66]. This attachment is divided by the bifurcate ridge and bordered by the intercondylar ridge [66]. The tibial attachment is a broad, irregular, oval-shaped area (30 mm long and 10 mm wide) slightly medial and anterior to the midline and between the medial and lateral tibial spinous processes [65]. It is located immediately medial to the attachment of the anterior horn of the lateral meniscus and posterior to the tubercle of the anterior horn of the medial meniscus [66]. The ACL has two bundles named according to their tibial insertions: the anteromedial bundle and the posterolateral bundle [65]. The anteromedial bundle originates proximal to the bifurcate ridge, is tight in knee flexion [65, 70], and primarily resists anterior tibial translation in knee flexion [66]. It increases anterior tibial translation at 60° and 90° of knee flexion [70]. The posterolateral bundle originates distal to the bifurcate ridge, is tight in knee extension [65, 70], and primarily resists rotatory loads in knee extension [66]. It is responsible for preventing the pivot-shift phenomenon and stabilizes against anterior translation with 30° of knee flexion [70].

The posterior cruciate ligament (PCL) runs from the lateral aspect of the medial femoral condyle to the posterior aspect of the tibia, just below the joint line [42, 78]. It prevents posterior subluxation of the tibia on the femur [42] and resists posterior tibial translation at all degrees of knee flexion [66]. The PCL is the largest of the intra-articular ligaments, with an average length of 38 mm and a mean diameter at the midpoint of 13 mm [70, 78]. Its cross-sectional area is approximately 120% to 150% greater than that of the ACL [78]. The PCL is most narrow in its midsubstance, fanning out at both the femoral origin and the tibial insertion [78]. It has two distinct bundles defined by their insertion on the femur: an anterolateral (AL) bundle and a posteromedial (PM) bundle [78]. The AL bundle is larger and comprises 85% of the PCL's cross-sectional area [78]. The femoral attachment is a broad, semicircular area on the anterolateral medial femoral condyle with a mean length of 30 mm and mean width of 5 mm [70, 78]. In the coronal plane, the PCL attachment is typically between 12 and 4 o'clock in the right knee, and between 12 and 8 o'clock in the left knee [78]. The insertion of the two PCL bundles is separated by a medial bifurcate ridge [78]. The PCL inserts onto a midline depression on the tibia, 10 to 15 mm below the level of the medial and lateral tibial plateaus [70, 78]. The tibial fossa for the PCL is trapezoidal in shape [78]. The AL bundle occupies the superolateral aspect of the tibial footprint [78], while the PM bundle occupies the inferomedial aspect of the intercondylar fossa [78]. The anterolateral bundle is tight in knee flexion [70], and the posteromedial bundle is tight in knee extension [70].

The medial collateral ligament (MCL) has superficial and deep portions which stabilize the knee to valgus stresses [42]. The MCL originates on the femoral sulcus approximately 3.2 cm proximal and 4.8 cm posterior to the articular surface of the femur at the knee [70]. The adductor tubercle is a prominence on the medial condyle proximal to the MCL origin and is the site of insertion of the adductor magnus muscle [70]. The MCL superficial proximal division resists valgus tibial translation [66]. The MCL superficial distal division resists tibial external rotation in knee extension [66]. The deep MCL resists valgus translation [66]. The posterior oblique ligament resists tibial internal rotation, especially in knee extension [66].

The lateral collateral ligament (LCL), or fibular collateral ligament, runs from the lateral femoral condyle to the head of the fibula and is the main stabilizer against varus stress [42]. It resists varus tibial translation [66]. The LCL is part of the posterolateral “complex” or “corner” of the knee that also resists external rotation [42]. The popliteofibular ligament, present in 90% of knees, runs from the tendon of the popliteus muscle to the styloid on the posterior fibular head [42]. The popliteus tendon resists tibial external rotation, especially in knee flexion [66]. The popliteofibular ligament resists tibial external rotation, especially in knee flexion [66]. The oblique popliteal ligament resists knee hyperextension [66].

Meniscal Anatomy

The menisci are C-shaped fibrocartilaginous disks in the knee that provide shock absorption, allow for increased congruency between joint surfaces, enhance joint stability, and aid in distribution of synovial fluid [42]. They are crescent-shaped, fibrocartilaginous structures with a triangular cross section [70]. The menisci consist of type I collagen fibers arranged obliquely, radially, and vertically [70]. The medial and lateral menisci provide a concave surface with which the convex femoral condyles can articulate [42]. Without menisci, the convex femoral condyles articulate with the relatively flat tibial plateaus, decreasing surface area of contact and increasing pressure on the articular cartilage [42]. The medial meniscus is firmly attached to the joint capsule along its entire peripheral edge [42]. It is crescent-shaped and attaches more anterior and posterior [70]. The medial meniscus has less mobility than the lateral meniscus and is more susceptible to tearing when trapped between the femoral condyle and tibial plateau [42]. The lateral meniscus is attached to the anterior and posterior capsule, but there is a region posterolaterally where it is not firmly attached [42]. It is circular in shape and covers a larger proportion of the tibial plateau [70]. The lateral meniscus is larger than the medial meniscus and carries a greater share of the lateral compartment pressure than the medial meniscus carries for the medial compartment [42]. The anterior attachment of the lateral meniscus is adjacent to the tibial insertion of the ACL [70]. The menisci are attached to collateral ligaments via coronary ligaments [70]. The vascular supply of the menisci is derived from the geniculate arteries, which penetrate into 20% to 30% of the peripheral medial meniscus and 10% to 25% of the peripheral lateral meniscus [70].

Vascular and Neural Anatomy

The blood supply to the knee is formed from an anastomosis around the knee derived from the descending geniculate artery, medial and lateral superior geniculate arteries, medial and lateral inferior geniculate arteries, middle geniculate artery, and anterior tibial recurrent arteries [65]. The middle geniculate artery supplies both the anterior and posterior cruciate ligaments [65] and is the primary blood supply to the ACL [70] and PCL [70]. The inferior geniculate arteries pass deep to their respective collateral ligaments [65]. The blood supply of the patella is derived from the geniculate artery complex with some contribution from the anterior tibial recurrent artery and primarily exists in the middle to inferior portions of the patella [65]. The popliteus artery travels through the adductor hiatus, where it is relatively immobile, and distally through the fibrous arch deep to the soleus muscle [75]. The popliteal artery is near the PCL, and the distance increases with knee flexion [70].

The knee is innervated by branches of the femoral nerve (L2, L3, L4), obturator nerve (L2, L3, L4), and sciatic nerve (L4, L5, S1, S2) [65]. The largest nerve providing innervation of the intra-articular knee is the posterior articular branch of the tibial nerve [65]. This branch supplies the infrapatellar fat pad, the synovial covering over the cruciate ligaments, and the periphery of the meniscus [65]. It also provides innervation to the ACL [70] and PCL [70]. Nerves to the cruciate ligaments contain vasomotor and pain fibers as well as mechanoreceptors that may be involved in proprioception [65]. The infrapatellar branch of the saphenous nerve arises proximal to the knee joint medially and crosses distal to the patella to innervate the skin over the region of the anterior knee and proximal tibia [65]. The common peroneal nerve travels along the posterior edge of the biceps femoris and continues distally around the fibular neck [75]. The tibial nerve, after branching from the sciatic nerve, courses distally through the center of the popliteus fossa [75].

Synovial Anatomy

Embryologically, the knee joint forms from three synovial compartments that normally fuse into a single synovial cavity with the intervening synovial partitions resolving [77]. The important synovial plicae of the knee represent unresolved remnants of these partitions [77]. Synovial plicae are usually classified according to their anatomic relationship to the patella: suprapatellar, infrapatellar, medial patellar, and lateral patellar plicae [77]. The infrapatellar plica, or ligamentum mucosum, can vary from a thin band of synovium running from the back side of the fat pad into the intercondylar notch to a nearly complete synovial partition separating the medial and lateral compartments [77]. The suprapatellar plica is superior to the patella and partially divides the suprapatellar pouch into two compartments [77]. The medial patellar plica begins just superior to the patella and sometimes continues with the distal extent of the suprapatellar plica, running distally along the medial side wall of the fat pad [77]. The incidence of the medial patellar plica has been reported to range from 10% to more than 50% in normal knees [77]. In some patients, a median septum separates the posterior aspect of the knee into two compartments [80]. The posterior cruciate ligament is extrasynovial and projects anteriorly in the septum, contributing to the partition between the two posterior compartments [80].

Classification

Septic arthritis of the adult knee and hip is a surgical urgency most commonly caused by S. aureus, with increasing rates of MRSA [5]. The pathogen spectra of periprosthetic and native joint infections differ considerably [137]. In pediatric knee septic arthritis, K. kingae is an emerging frequent isolate, with a recent Swiss study finding an 82% rate in joint infection in under 4-year-olds [60]. K. pneumoniae septic arthritis is extremely uncommon [22].

Periprosthetic Joint Infection Temporal Classification: Periprosthetic joint infections are categorized into four types based on duration and interval from the index procedure: early postoperative, acute hematogenous, late chronic, and positive intraoperative cultures found at revision for presumed aseptic failure [128]. Early periprosthetic joint infections are defined as occurring within three months after surgery [119]. Delayed periprosthetic joint infections are defined as appearing between three and 24 months after surgery [119]. Late periprosthetic joint infections are defined as emerging more than 24 months after surgery [119].

Staging Systems: A staging system for periprosthetic infections incorporates the infection classification system with the status of the host, including both systemic and local compromising factors [128]. Reinfection in two-stage revision for periprosthetic infection is evaluated using a staging system that grades patients according to infection type (I, II, III), systemic host grade (A, B, C), and local extremity grade (1, 2, 3) [50]. An arthroscopic staging of the initial joint infection has prognostic and therapeutic consequences [24].

Other Considerations: There is no validated prognostic staging classification for children with septic arthritis of the knee [60].

Clinical Presentation

Diagnostic Criteria and Laboratory Findings

Laboratory data combined with clinical symptoms are an essential component of the proper diagnosis of septic arthritis [93]. The Kocher criteria for differentiating septic arthritis from transient synovitis include fever >101.3°F, refusal to bear weight, leukocyte count >12,000, and ESR >40 [93]. The diagnostic sensitivity for septic arthritis was 93% when 3 Kocher criteria were positive and 99% when all 4 criteria were positive [93]. However, if the identical Kocher criteria were applied to the knee, 52% of septic knee cases could be missed [93]. One study noted only a 59% predicted probability of having septic arthritis in patients with all 4 Kocher criteria being positive [93]. Organisms such as Kingella with a less severe presentation can be missed by a strictly parameter-based approach to septic arthritis [93].

CRP greater than 2 mg/dL is an independent risk factor for septic arthritis [93]. In a modified criteria study, fever >38.5°C was the best predictor of septic arthritis, followed by an elevated CRP level, an elevated ESR, refusal to bear weight, and an elevated serum white blood cell count [93]. In this modified criteria study, patients with 5 positive criteria had a 98% chance of having septic arthritis, those meeting 4 criteria had a 93% chance, and those meeting 3 criteria had an 83% chance [93]. The efficacy of conventional microbiological testing in the diagnostics of different types of joint infections is questionable [33]. A machine learning-based prediction model might improve the diagnosis of septic arthritis of the knee [20].

Clinical Signs and Physical Examination

In acute septic arthritis due to Clostridium welchii, local and systemic findings were similar to other pyarthroses [37]. Post-steroid septic arthritis can present with mild clinical findings but have tremendous consequences with a very long recovery time [14]. A detailed physical examination of the knee includes inspection, palpation, gait assessment, range of motion testing, stability testing, neurovascular assessment, a hip examination, and special tests aimed at the diagnosis of particular pathologies [98].

Inspection of the knee can reveal skin abnormalities, evidence of trauma, malalignment, and swelling [98]. Palpation of the peripatellar tissue can reveal the presence of effusion and/or synovitis [98]. Blocks to motion during range of motion testing can be pain-related or mechanical [98]. When active and passive ranges of motion differ, the diagnostician must differentiate between pain-related, mechanical, or neuromuscular causes [98]. Hip range of motion should be examined and may reveal resultant knee pain, indicating the possibility of referred pain from intra-articular hip pathology [98].

A hemophiliac with acute intra-articular bleeding has a warm, swollen, and tender joint, frequently without a history of trauma; these findings are similar to those of septic arthritis [94]. In a retrospective series of 24 patients with septic arthritis after ACL reconstruction, the average white blood cell count on presentation was 9500 (range, 3300-17,000) and the average CRP was 4.8 (range, 0.5-17.4) [92].

Differential Diagnosis and Mimics

Tenosynovial giant-cell tumor should be considered as part of the differential for a patient with acute onset knee pain and effusion without a history of trauma and with a lack of systemic symptoms [106]. Persistence or recurrence of clinical signs of infection after management of septic knee arthritis in adults should raise the suspicion of adjacent osteomyelitis, especially in patients with comorbid conditions [1]. A high index of suspicion may result from careful examination of plain radiographs, and further imaging studies, including CT or MRI, are essential for diagnosis of septic knee arthritis with adjacent chronic osteomyelitis [19].

The possibility of sepsis is rarely considered in hemophiliacs because the history supports the diagnosis of hemarthrosis so strongly that no further tests are performed [94]. Secondary, perhaps hematogenous, infection of the affected joint can occur in hemophiliacs with hemarthrosis [94].

Postoperative and Specific Contexts

Although postoperative septic arthritis is rare after ACL reconstruction, it carries a high morbidity that results in poor clinical outcome [2]. Although postoperative septic arthritis is rare after arthroscopically guided ACL reconstruction, it carries a high morbidity that results in protracted hospitalization and ultimately a less favorable clinical outcome [6]. Postoperative septic arthritis is rare but serious after arthroscopic ACL reconstruction [17].

It is important to direct empirical antimicrobials at MRSA in patients presenting with adult haematogenous native joint septic arthritis, especially those with recent health care system exposure [34]. Septic arthritis developing due to migration of an intramedullary nail into the knee is an extremely rare complication [113].

Investigations

Diagnostic Principles and Urgency: Septic arthritis of the adult knee is a surgical urgency most commonly caused by S. aureus, with increasing rates of MRSA [5]. The diagnosis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected [11].

Imaging Modalities: Plain radiography: A high index of suspicion for septic knee arthritis with adjacent chronic osteomyelitis may result from careful examination of plain radiographs [19]. MRI: Further imaging studies, including CT or MRI, are essential for diagnosis when plain radiographs suggest septic arthritis with adjacent chronic osteomyelitis [19]. In contrast to radiograph analyses, MRI was excellent at distinguishing damage to the cartilage and can be useful in early follow-up evaluation of patients with septic arthritis after ACL reconstruction [27]. MRI is the most useful study for differentiating osteonecrosis from other conditions, with serpentine lesions within a well-demarcated border being a specific finding on MRI for osteonecrosis [90]. CT: CT is an essential further imaging study for the diagnosis of septic knee arthritis with adjacent chronic osteomyelitis [19]. Bone scan: Based on a low certainty of evidence, SPECT/CT is currently one of the most accurate modalities available to aid the diagnosis of aseptic loosening of knee arthroplasty components [121]. Tomosynthesis: No specific evidence provided. Aspiration: Diagnostic joint aspiration must be immediately performed when the diagnosis is suspected [11]. Laboratory: Knee periprosthetic joint infection (PJI) is more often identified by current MSIS histological than microbiological criteria [25]. The Synovasure PJI assay does not accurately diagnose native joint septic arthritis nor provide utility in distinguishing septic vs crystalline arthritis [144]. Data suggest enhanced expression and activation of MMP-9 in septic native knee arthritis compared with aseptic arthritis [147].

Other Considerations: The diagnosis of septic arthritis of the knee might be improved using a machine learning-based prediction model [20].

Treatment

General Principles and Urgency

Septic arthritis of the knee constitutes a surgical emergency requiring immediate intervention to minimize long-term sequelae [60]. Infection of the knee is a devastating process; rapid surgical and antibiotic care facilitated by orthopaedic surgeons is essential to prevent further cartilage destruction [103]. Multidisciplinary management improves treatment success, with failure rates significantly decreasing after the establishment of Bone and Joint Infection Referral Centers [30].

Surgical Approach: Arthroscopy vs. Arthrotomy

Arthroscopy is as effective as arthrotomy in treating adult knee septic arthritis, but it demonstrates a lower reinfection rate and less frequent clinical signs of initial inflammatory reaction [51]. Available evidence indicates that arthroscopy results in a lower reoperation rate than arthrotomy [23]. For acute native knee septic arthritis, arthroscopic treatment was a more successful index procedure requiring fewer total irrigation procedures compared with open treatment [16]. No significant long-term functional differences were observed among arthroscopy combined with continuous irrigation, arthroscopic debridement alone, and open arthrotomy [4]. Patients undergoing arthroscopic treatment showed no difference in relative risk of perioperative complications, length of stay, or hospital cost compared with those undergoing open arthrotomy [32]. Arthroscopic debridement can serve as an alternative first-line option in managing septic arthritis [58]. Medical methods may be as effective as surgical methods for functional recovery in patients with septic arthritis [105].

Debridement and Antibiotic Therapy

Most (62%) of septic joints were managed effectively with a single surgical debridement [18]. Arthroscopic debridement combined with antibiotic treatment can lead to successful eradication of infection and graft salvage, with satisfactory functional outcomes in many cases of septic arthritis following ACL reconstruction [31]. Aggressive debridement with graft and hardware removal effectively controls infection in persistent septic arthritis of the knee after ACL reconstruction [131]. Surgery is recommended as the primary treatment for septic arthritis after ACL reconstruction, as conservative methods, while effective in some cases, often result in longer recovery periods and less favorable outcomes [13]. Arthroscopic drainage associated with antibiotic therapy is an effective treatment for childhood septic arthritis of the knee, providing good medium-term functional and radiological results [60]. Complete arthroscopic synovectomy in the management of recalcitrant septic arthritis offers advantages including better visibility of gutters and areas not visible by open arthrotomy, and less postoperative pain allowing early mobilization [63]. Risks of complete arthroscopic synovectomy include injury to the popliteal artery, common peroneal nerve, saphenous nerve and its branches, and femoral origins of the collateral ligaments [63].

Outcomes and Complications

Septic arthritis after ACLR did not result in inferior objective knee function compared with uncomplicated ACLR [3]. Intravenous drug use (IDU) is increasingly the cause of septic knee admissions and is associated with higher rates of mortality, reoperations, resource utilization, and leaving against medical advice [48].

Arthroplasty and Revision Considerations

Patients with a history of treated septic arthritis are at high risk of developing periprosthetic joint infection after total joint arthroplasty, with the risk appearing greater in knee arthroplasty compared to hip arthroplasty [7]. Management of septic arthritis by arthroplasty using the present protocol gave very good functional results in both knee and hip, with 87% eradication of infection in evolutive septic arthritis and 95% in quiescent septic arthritis [8]. Single-stage TKA is a suitable option for patients with a prior septic arthritis of the knee, provided that proper surgical technique and the utilization of systemic and local antibiotics are employed [15]. Consistent infection eradication was found at a 1-year follow-up with postoperative range of motion and knee scores comparing favourably with those of other case series for short-interval two-stage approach to primary total knee arthroplasty for acutely septic osteoarthritic knees [10]. Knee mobility and HSS scores were significantly improved postoperation in both treatment groups for staged joint replacement in patients with septic arthritic knee [21]. Recent or current knee sepsis is an absolute contraindication to total knee arthroplasty [46]. There is conflicting evidence regarding the benefit of extended (>24 hours) antibiotics, IV or PO, after TJA [36].

Periprosthetic Joint Infection (PJI) Management

Open debridement is superior to arthroscopic debridement for the treatment of acutely infected total knee arthroplasty, with a 29% greater success rate for open procedures [110]. DAIR (debridement, antibiotics, and implant retention) is recommended as a choice for patients with current infection within 12 weeks after primary TKA [115]. Success of DAIR in prosthetic joint infection following primary total knee arthroplasty was highest in infections occurring <1 month of the primary TKA and progressively decreased as time since the primary TKA increased [116]. Two-stage revision of septic knee prosthesis with articulating knee spacers yields better infection eradication rate than one-stage or two-stage revision with static spacers [35]. Treatment of infected total knee arthroplasty using an articulating spacer achieved soft tissue compliance, allowed for ease of operation, reduced postoperative pain, improved function, and eradicated infection equal to standards reported in the literature [107]. Excellent clinical and radiographic midterm outcomes were achieved with a low complication rate using tantalum metaphyseal cones for the management of severe bone defects in septic knee revision [56].

Salvage Procedures

When the knee is not amenable to reconstruction, arthrodesis is usually the last option available to the surgeon to obtain a painless, stable knee [45]. Successful fusion is achieved in more than 90% of patients undergoing knee arthrodesis [45]. The most common indication for knee arthrodesis is the nonreconstructable TKA that has failed, usually because of infection and loss of the extensor mechanism [45]. Less common indications include septic arthritis, osteomyelitis, posttraumatic arthritis in a young manual laborer, painful ankylosis, neuropathic knee (Charcot joint), and paralytic deformity [45]. Contraindications for knee arthrodesis include bilateral knee involvement and ipsilateral hip arthrodesis [45]. If the limb-length discrepancy is less than 2 cm, the knee is placed in 5° to 7° of valgus and 15° of flexion for arthrodesis [45]. If the limb-length discrepancy is 2 to 4 cm, the knee is placed in extension to enable ground clearance for arthrodesis [45]. If the limb-length discrepancy is greater than 4 cm, bone grafting or a prosthetic spacer to limit gait abnormalities can be considered for arthrodesis [45]. Complications of knee arthrodesis include painful nonunion (most common), infection, deep vein thrombosis, peroneal nerve palsy, and wound dehiscence [45]. Long-term complications include hip, spine, and ankle pain because of the altered gait pattern [45]. The functional results of knee arthodesis using a modular customized intramedullary nail are comparable to those in the literature, and the technique is simple and reliable [52].

Complications

Infection Persistence and Recurrence

Post-ACL Reconstruction: The prevalence of septic arthritis following ACL reconstruction is 1.8% in specific series [41]. Aggressive progression of septic arthritis and osteomyelitis has been documented in healthy patients after this procedure [26].

Arthroplasty and Periprosthetic Joint Infection (PJI): Management of septic arthritis via arthroplasty using a specific protocol yields very good functional results in both knee and hip joints, with infection eradication rates of 87% in evolutive septic arthritis and 95% in quiescent septic arthritis [8]. Consistent infection eradication is observed at 1-year follow-up, with postoperative range of motion and knee scores comparing favourably to other case series in short-interval two-stage approaches [10]. However, survivorship free from persistent PJI at 1 year is low at 76%, consistent with similar reports of DAIRs for total knee arthroplasties [29]. The risk of failure after one-year follow-up remains high following revision for periprosthetic joint infection [54]. Salvage of an infection-free prosthetic knee was achieved in only about two thirds of cases following reinfection after prior staged reimplantation [40]. The prevalence of multiple periprosthetic joint infections has decreased compared with historical reports, likely due to higher rates of 2-stage revisions and fewer patients treated with I&D [124].

Microbiology and Risk Factors: The probability of treatment failure, defined as removal of implants, was not significantly different among patients treated with single versus multiple I&Ds for periprosthetic joint infections [120]. Patients treated with multiple I&Ds for periprosthetic joint infections had a significantly higher prevalence of peripheral vascular disease [120].

Wound Complications

Wound Complications: Wound complications after total knee arthroplasty increase cost, length of hospitalization, readmission rates, and the risk of deep infection [127].

Other Considerations

Aseptic Loosening: Aseptic loosening became more important with longer follow-up in the context of modern knee arthroplasty failure analysis [125].

Recovery

General Prognosis and Functional Outcomes: Postoperative septic arthritis following ACL reconstruction carries a high morbidity that results in poor clinical outcome [2]. This condition is associated with protracted hospitalization and ultimately a less favorable clinical outcome [6]. In acute septic arthritis due to Clostridium welchii, local and systemic findings were similar to other pyarthroses, with apparently little or no cartilage destruction and subsequent excellent functional recovery [37]. The prognosis for complete return of joint function in Hemophilus influenzae septic arthritis is excellent if appropriate therapy is initiated promptly [47].

Imaging and Follow-up: MRI was excellent at distinguishing damage to the cartilage and can be useful in early follow-up evaluation of patients with septic arthritis after ACL reconstruction [27].

Surgical Management and Infection Eradication: Consistent infection eradication was found at a 1-year follow-up with postoperative range of motion and knee scores comparing favourably with those of other case series in short-interval two-stage primary total knee arthroplasty for acutely septic osteoarthritic knees [10]. The two-stage procedure for the treatment of infected arthritic knees after failed eradication surgery was effective in all patients [149].

Periprosthetic Joint Infection (PJI) and Revision Outcomes: Continued investigation is required to determine the fate of infected joints that undergo DAIR with regard to ultimate patient outcome [39]. Salvage of an infection-free prosthetic knee was achieved in only about two thirds of the cases after reinfection following prior staged reimplantation for septic total knee arthroplasty [40]. One-stage revision of septic knee prostheses achieved an infection control rate of 95% and higher knee scores than reported for two-stage revisions [53]. While 10-year survivorship free of aseptic revision was 88%, periprosthetic joint infection led to the poorer survivorship free of any revision of 70% at 10 years in patients with neuropathic (Charcot) arthropathy [134]. Two-stage re-implantation with an articulating spacer for infected TKA effectively treats infection and gives excellent knee motion between stages, and at mid- to long-term follow-up [138]. Successful outcomes are possible with prolonged combination antibiotics and often require 2-stage revision arthroplasty for Brucella periprosthetic joint infections following total knee arthroplasty [148].

Key Evidence

  • [L3] Persistence or recurrence of clinical signs of infection after management of septic knee arthritis in adults should raise the suspicion of adjacent osteomyelitis, especially in patients with comorbid conditions. [1] (10.1097/01.blo.0000229336.44524.65)
  • [L4] Although postoperative septic arthritis is rare after ACL reconstruction, it carries a high morbidity that results in poor clinical outcome. [2] (10.1007/s00167-009-0793-1)
  • [L3] Septic arthritis after ACLR did not result in inferior objective knee function compared with uncomplicated ACLR. [3] (10.1016/j.arthro.2014.03.019)
  • [L3] No significant long-term functional differences were observed among the three surgical methods used to treat septic arthritis of the knee. [4] (10.1186/s12891-025-08724-7)
  • [L5] Septic arthritis of the adult knee and hip is a surgical urgency most commonly caused by S aureus with increasing MRSA rates. [5] (10.1016/j.arth.2019.10.062)
  • [L4] Although postoperative septic arthritis is rare after arthroscopically guided ACL reconstruction, it carries a high morbidity that results in protracted hospitalization and ultimately a less favorable clinical outcome. [6] (10.1177/03635465990270050301)
  • [L3] Patients with a history of treated septic arthritis are at high risk of developing periprosthetic joint infection after total joint arthroplasty, with the risk appearing greater in knee arthroplasty compared to hip arthroplasty. [7] (10.1097/corr.0000000000000734)
  • [L4] Management of septic arthritis by arthroplasty using the present protocol gave very good functional results in both knee and hip, with 87% of eradication of infection in evolutive septic arthritis and 95% in quiescent septic arthritis. [8] (10.1016/j.otsr.2010.06.009)
  • [L3] In the knee, such cases had inferior infection-free survival at two years compared with those with negative cultures; there was no difference between the groups following THA. [9] (10.1302/0301-620x.99b11.bjj-2016-0655.r2)
  • [L5] Consistent infection eradication was found at a 1-year follow-up with postoperative range of motion and knee scores comparing favourably with those of other case series. [10] (10.1007/s00167-016-3982-8)
  • [L4] The diagnosis of septic knee arthritis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected. [11] (10.1007/s00167-006-0224-5)
  • [L4] The authors recommend surgery as the primary treatment for septic arthritis after ACL reconstruction, noting that while conservative methods can be effective in some cases, they often result in longer recovery periods and less favorable outcomes. [13] (10.1016/j.arthro.2009.06.012)
  • [L4] Post-steroid septic arthritis can present with mild clinical findings but have tremendous consequences with a very long recovery time. [14] (10.1007/s00167-008-0679-7)
  • [L3] Single-stage TKA is a suitable option for patients with a prior septic arthritis of the knee, provided that proper surgical technique and the utilization of systemic and local antibiotics are employed. [15] (10.1016/j.arth.2020.02.065)
  • [L3] Arthroscopic treatment for acute native knee septic arthritis was a more successful index procedure and required fewer total irrigation procedures compared with open treatment. [16] (10.2106/jbjs.16.00110)
  • [L4] Postoperative septic arthritis is rare but serious after arthroscopic ACL reconstruction. [17] (10.1177/0363546515603054)
  • [L4] Most (62%) of the septic joints were managed effectively with a single surgical debridement. [18] (10.2106/jbjs.n.00593)
  • [L4] A high index of suspicion may result from careful examination of plain radiographs, and further imaging studies, including CT or MRI, are essential for diagnosis of septic knee arthritis with adjacent chronic osteomyelitis. [19] (10.1007/s00167-009-0976-9)
  • [L3] The diagnosis of septic arthritis of the knee might be improved using a machine learning-based prediction model. [20] (10.1007/s00167-020-06418-2)
  • [L4] Knee mobility and HSS scores were significantly improved postoperation in both treatment groups. [21] (10.1186/s13018-020-02062-1)
  • [L5] K pneumoniae septic arthritis is extremely uncommon. [22] (10.1016/j.arth.2007.12.018)
  • [L1] Based on the available evidence, arthroscopy for the treatment of septic arthritis of the knee results in a lower reoperation rate than arthrotomy. [23] (10.1136/jisakos-2018-000269)
  • [L4] An arthroscopic staging of the initial joint infection has prognostic and therapeutic consequences. [24] (10.1007/s001670000129)
  • [L3] Knee PJI is more often identified by current MSIS histological than microbiological criteria. [25] (10.1007/s00402-019-03159-x)
  • [L4] The authors presented a previously unpublished aggressive progression of septic arthritis and osteomyelitis after ACL reconstruction in a healthy patient. [26] (10.1007/s00167-007-0424-7)
  • [L2] In contrast to radiograph analyses, MRI was excellent at distinguishing damage to the cartilage and can be useful in early follow-up evaluation of patients with septic arthritis after ACL reconstruction. [27] (10.1177/23259671211052519)
  • [L3] Survivorship free from persistent PJI at 1 year is low at 76% but is consistent with similar reports of DAIRs for total knee arthroplasties. [29] (10.1016/j.arth.2020.02.036)
  • [L3] Multidisciplinary management of septic arthritis improved treatment success, with the failure rate significantly decreasing after setting up the Bone and Joint Infection Referral Center. [30] (10.1016/j.otsr.2018.08.006)
  • [L1] Arthroscopic debridement combined with antibiotic treatment can lead to successful eradication of infection and graft salvage, with satisfactory functional outcomes in many cases of septic arthritis following ACL reconstruction. [31] (10.1302/0301-620x.98b5.35990)
  • [L3] Patients undergoing arthroscopic treatment of septic arthritis of the knee showed no difference in relative risk of perioperative complications, length of stay, or hospital cost compared with patients who underwent open arthrotomy. [32] (10.1055/s-0039-1693450)
  • [L4] Based on our data, the efficacy of conventional microbiological testing in the diagnostics of different type of joint infections is questionable. [33] (10.1016/j.injury.2020.02.058)
  • [L3] It is important to direct empirical antimicrobials at MRSA in patients presenting with adult haematogenous native joint septic arthritis, especially those with recent health care system exposure. [34] (10.1007/s00402-007-0285-z)
  • [L4] [35] (10.1007/s00167-012-1885-x)
  • [L1] There is conflicting evidence regarding the benefit of extended (>24 hours) antibiotics, IV or PO, after TJA. [36] (10.5435/jaaos-d-21-00977)
  • [L4] In acute septic arthritis due to Clostridium welchii, local and systemic findings were similar to other pyarthroses, with apparently little or no cartilage destruction and subsequent excellent functional recovery. [37] (10.2106/00004623-196850060-00015)
  • [L3] Continued investigation is required to determine the fate of infected joints that undergo DAIR with regard to ultimate patient outcome. [39] (10.1097/corr.0000000000003138)
  • [L3] Salvage of an infection-free prosthetic knee was achieved in only about two thirds of the cases. [40] (10.1016/j.arth.2010.04.017)
  • [L4] The prevalence of septic arthritis after an ACL reconstruction in this series was 1.8%. [41] (10.1007/s00167-012-2264-3)
  • [L4] The prognosis for complete return of joint function in this infection is excellent if appropriate therapy is initiated promptly. [47] (10.2106/00004623-197456020-00021)
  • [L3] IDU is increasingly the cause of septic knee admissions and is associated with higher rates of mortality, reoperations, resource utilization, and leaving against medical advice. [48] (10.1097/01.blo.0000534682.68856.d8)
  • [L2] [50] (10.1007/s00264-011-1267-x)
  • [L1] Arthroscopy is as effective as arthrotomy in the treatment of septic arthritis of the knee in adults, but arthroscopy has demonstrated a lower reinfection rate and less frequent clinical signs of initial inflammatory reaction. [51] (10.1007/s00167-015-3918-8)
  • [L4] The functional results are comparable to those in the literature, and the technique is simple and reliable. [52] (10.1016/j.otsr.2009.07.006)
  • [L3] One-stage revision of septic knee prostheses achieved an infection control rate of 95% and higher knee scores than reported for two-stage revisions. [53] (10.1007/s11999-011-2174-6)
  • [L3] The risk of failure after one-year follow-up is high after revision for periprosthetic joint infection. [54] (10.1002/ksa.12762)
  • [L3] Excellent clinical and radiographic midterm outcomes were achieved with a low complication rate. [56] (10.1016/j.arth.2018.08.026)
  • [L3] These findings conclude that arthroscopic debridement can be an alternative first-line option in managing septic arthritis. [58] (10.1007/s00167-018-5328-1)
  • [L4] [60] (10.1016/j.otsr.2015.09.007)
  • [Paper] [63] (10.1016/j.eats.2016.11.002)
  • [L4] [92] (10.1177/0363546507299744)
  • [L5] [93] (10.5435/jaaos-d-20-00835)
  • [Case_report] [94] (10.2106/00004623-198365020-00021)
  • [L3] Medical methods may be as effective as surgical methods for functional recovery in patients with septic arthritis. [105] (10.1186/s12891-024-08147-w)
  • [L5] This case illustrates that TGCT should be considered as part of the differential for a patient with acute onset knee pain and effusion without a history of trauma and with a lack of systemic symptoms. [106] (10.5435/jaaosglobal-d-20-00089)
  • [L4] [107] (10.1097/01.blo.0000149241.77924.01)
  • [L3] Open debridement is superior to arthroscopic debridement for the treatment of acutely infected total knee arthroplasty, with a 29% greater success rate for open procedures. [110] (10.1016/j.arth.2020.06.039)
  • [L5] Septic arthritis developing due to migration of an intramedullary nail into the knee is an extremely rare complication. [113] (10.1016/s0020-1383(13)70143-8)
  • [L3] We recommended DAIR as a choice for patients with current infection within 12 weeks after primary TKA. [115] (10.1186/s13018-022-03218-x)
  • [L2] Success was highest in infections occurring <1 month of the primary TKA and progressively decreased as time since the primary TKA increased. [116] (10.1016/j.arth.2023.04.024)
  • [L1] [119] (10.1016/j.jisako.2023.09.003)
  • [L3] [120] (10.1016/j.arth.2015.06.051)
  • [L3] Based on a low certainty of evidence, MRI and SPECT/CT are currently the most accurate modalities available to aid the diagnosis of aseptic loosening of knee arthroplasty components. [121] (10.1002/ksa.12206)
  • [L4] The prevalence of multiple periprosthetic joint infections has decreased compared with historical reports, likely due to higher rates of 2-stage revisions and fewer patients treated with I&D. [124] (10.1016/j.arth.2016.05.013)
  • [L3] Aseptic loosening became more important with longer followup. [125] (10.1007/s11999-017-5396-4)
  • [L5] Wound complications after total knee arthroplasty increase cost, length of hospitalization, readmission rates, and the risk of deep infection; prevention is ideal through optimal patient health, careful planning, and detailed postoperative care. [127] (10.1016/j.arth.2007.03.014)
  • [L4] [128] (10.1007/s11999-010-1293-9)
  • [L4] Aggressive debridement with graft and hardware removal effectively controls infection in persistent septic arthritis of the knee after ACL reconstruction. [131] (10.1097/01.blo.0000181499.49740.e5)
  • [L4] While 10-year survivorship free of aseptic revision was 88%, periprosthetic joint infection led to the poorer survivorship free of any revision of 70% at 10 years. [134] (10.1016/j.arth.2018.04.003)
  • [L3] The pathogen spectra of periprosthetic and native joint infections differ considerably. [137] (10.1186/s13018-021-02850-3)
  • [L4] Two-stage re-implantation with an articulating spacer for infected TKA effectively treats infection and gives excellent knee motion between stages, and at mid- to long-term follow-up. [138] (10.1016/j.arth.2008.04.003)
  • [L4] The Synovasure PJI assay does not accurately diagnose native joint septic arthritis nor provide utility in distinguishing septic vs crystalline arthritis. [144] (10.1016/j.arth.2021.03.020)
  • [L4] The data presented suggest enhanced expression and activation of MMP-9 in septic native knee arthritis compared with aseptic. [147] (10.1007/s00167-011-1676-9)
  • [L3] Successful outcomes are possible with prolonged combination antibiotics and often require 2-stage revision arthroplasty, though diagnostic and treatment approaches vary widely. [148] (10.2106/jbjs.rvw.25.00079)
  • [L4] The two-stage procedure for the treatment of infected arthritic knees after failed eradication surgery was effective in all patients. [149] (10.1007/s00167-020-06106-1)

See Also

References

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Creative Commons public licenses provide a standard set of terms and conditions that creators and other rights holders may use to share original works of authorship and other material subject to copyright and certain other rights specified in the public license below. The following considerations are for informational purposes only, are not exhaustive, and do not form part of our licenses.

Considerations for licensors: Our public licenses are intended for use by those authorized to give the public permission to use material in ways otherwise restricted by copyright and certain other rights. Our licenses are irrevocable. Licensors should read and understand the terms and conditions of the license they choose before applying it. Licensors should also secure all rights necessary before applying our licenses so that the public can reuse the material as expected. Licensors should clearly mark any material not subject to the license. This includes other CC- licensed material, or material used under an exception or limitation to copyright. More considerations for licensors: wiki.creativecommons.org/Considerations_for_licensors

Considerations for the public: By using one of our public licenses, a licensor grants the public permission to use the licensed material under specified terms and conditions. If the licensor's permission is not necessary for any reason--for example, because of any applicable exception or limitation to copyright--then that use is not regulated by the license. Our licenses grant only permissions under copyright and certain other rights that a licensor has authority to grant. Use of the licensed material may still be restricted for other reasons, including because others have copyright or other rights in the material. A licensor may make special requests, such as asking that all changes be marked or described. Although not required by our licenses, you are encouraged to respect those requests where reasonable. More considerations for the public: wiki.creativecommons.org/Considerations_for_licensees

Creative Commons Attribution-NonCommercial 4.0 International Public License

By exercising the Licensed Rights (defined below), You accept and agree to be bound by the terms and conditions of this Creative Commons Attribution-NonCommercial 4.0 International Public License ("Public License"). To the extent this Public License may be interpreted as a contract, You are granted the Licensed Rights in consideration of Your acceptance of these terms and conditions, and the Licensor grants You such rights in consideration of benefits the Licensor receives from making the Licensed Material available under these terms and conditions.

Section 1 -- Definitions.

a. Adapted Material means material subject to Copyright and Similar Rights that is derived from or based upon the Licensed Material and in which the Licensed Material is translated, altered, arranged, transformed, or otherwise modified in a manner requiring permission under the Copyright and Similar Rights held by the Licensor. For purposes of this Public License, where the Licensed Material is a musical work, performance, or sound recording, Adapted Material is always produced where the Licensed Material is synched in timed relation with a moving image.

b. Adapter's License means the license You apply to Your Copyright and Similar Rights in Your contributions to Adapted Material in accordance with the terms and conditions of this Public License.

c. Copyright and Similar Rights means copyright and/or similar rights closely related to copyright including, without limitation, performance, broadcast, sound recording, and Sui Generis Database Rights, without regard to how the rights are labeled or categorized. For purposes of this Public License, the rights specified in Section 2(b)(1)-(2) are not Copyright and Similar Rights.

d. Effective Technological Measures means those measures that, in the absence of proper authority, may not be circumvented under laws fulfilling obligations under Article 11 of the WIPO Copyright Treaty adopted on December 20, 1996, and/or similar international agreements.

e. Exceptions and Limitations means fair use, fair dealing, and/or any other exception or limitation to Copyright and Similar Rights that applies to Your use of the Licensed Material.

f. Licensed Material means the artistic or literary work, database, or other material to which the Licensor applied this Public License.

g. Licensed Rights means the rights granted to You subject to the terms and conditions of this Public License, which are limited to all Copyright and Similar Rights that apply to Your use of the Licensed Material and that the Licensor has authority to license.

h. Licensor means the individual(s) or entity(ies) granting rights under this Public License.

i. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. For purposes of this Public License, the exchange of the Licensed Material for other material subject to Copyright and Similar Rights by digital file-sharing or similar means is NonCommercial provided there is no payment of monetary compensation in connection with the exchange.

j. Share means to provide material to the public by any means or process that requires permission under the Licensed Rights, such as reproduction, public display, public performance, distribution, dissemination, communication, or importation, and to make material available to the public including in ways that members of the public may access the material from a place and at a time individually chosen by them.

k. Sui Generis Database Rights means rights other than copyright resulting from Directive 96/9/EC of the European Parliament and of the Council of 11 March 1996 on the legal protection of databases, as amended and/or succeeded, as well as other essentially equivalent rights anywhere in the world.

l. You means the individual or entity exercising the Licensed Rights under this Public License. Your has a corresponding meaning.

Section 2 -- Scope.

a. License grant.

1. Subject to the terms and conditions of this Public License, the Licensor hereby grants You a worldwide, royalty-free, non-sublicensable, non-exclusive, irrevocable license to exercise the Licensed Rights in the Licensed Material to:

a. reproduce and Share the Licensed Material, in whole or in part, for NonCommercial purposes only; and

b. produce, reproduce, and Share Adapted Material for NonCommercial purposes only.

2. Exceptions and Limitations. For the avoidance of doubt, where Exceptions and Limitations apply to Your use, this Public License does not apply, and You do not need to comply with its terms and conditions.

3. Term. The term of this Public License is specified in Section 6(a).

4. Media and formats; technical modifications allowed. The Licensor authorizes You to exercise the Licensed Rights in all media and formats whether now known or hereafter created, and to make technical modifications necessary to do so. The Licensor waives and/or agrees not to assert any right or authority to forbid You from making technical modifications necessary to exercise the Licensed Rights, including technical modifications necessary to circumvent Effective Technological Measures. For purposes of this Public License, simply making modifications authorized by this Section 2(a) (4) never produces Adapted Material.

5. Downstream recipients.

a. Offer from the Licensor -- Licensed Material. Every recipient of the Licensed Material automatically receives an offer from the Licensor to exercise the Licensed Rights under the terms and conditions of this Public License.

b. No downstream restrictions. You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, the Licensed Material if doing so restricts exercise of the Licensed Rights by any recipient of the Licensed Material.

6. No endorsement. Nothing in this Public License constitutes or may be construed as permission to assert or imply that You are, or that Your use of the Licensed Material is, connected with, or sponsored, endorsed, or granted official status by, the Licensor or others designated to receive attribution as provided in Section 3(a)(1)(A)(i).

b. Other rights.

1. Moral rights, such as the right of integrity, are not licensed under this Public License, nor are publicity, privacy, and/or other similar personality rights; however, to the extent possible, the Licensor waives and/or agrees not to assert any such rights held by the Licensor to the limited extent necessary to allow You to exercise the Licensed Rights, but not otherwise.

2. Patent and trademark rights are not licensed under this Public License.

3. To the extent possible, the Licensor waives any right to collect royalties from You for the exercise of the Licensed Rights, whether directly or through a collecting society under any voluntary or waivable statutory or compulsory licensing scheme. In all other cases the Licensor expressly reserves any right to collect such royalties, including when the Licensed Material is used other than for NonCommercial purposes.

Section 3 -- License Conditions.

Your exercise of the Licensed Rights is expressly made subject to the following conditions.

a. Attribution.

1. If You Share the Licensed Material (including in modified form), You must:

a. retain the following if it is supplied by the Licensor with the Licensed Material:

i. identification of the creator(s) of the Licensed Material and any others designated to receive attribution, in any reasonable manner requested by the Licensor (including by pseudonym if designated);

ii. a copyright notice;

iii. a notice that refers to this Public License;

iv. a notice that refers to the disclaimer of warranties;

v. a URI or hyperlink to the Licensed Material to the extent reasonably practicable;

b. indicate if You modified the Licensed Material and retain an indication of any previous modifications; and

c. indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License.

2. You may satisfy the conditions in Section 3(a)(1) in any reasonable manner based on the medium, means, and context in which You Share the Licensed Material. For example, it may be reasonable to satisfy the conditions by providing a URI or hyperlink to a resource that includes the required information.

3. If requested by the Licensor, You must remove any of the information required by Section 3(a)(1)(A) to the extent reasonably practicable.

4. If You Share Adapted Material You produce, the Adapter's License You apply must not prevent recipients of the Adapted Material from complying with this Public License.

Section 4 -- Sui Generis Database Rights.

Where the Licensed Rights include Sui Generis Database Rights that apply to Your use of the Licensed Material:

a. for the avoidance of doubt, Section 2(a)(1) grants You the right to extract, reuse, reproduce, and Share all or a substantial portion of the contents of the database for NonCommercial purposes only;

b. if You include all or a substantial portion of the database contents in a database in which You have Sui Generis Database Rights, then the database in which You have Sui Generis Database Rights (but not its individual contents) is Adapted Material; and

c. You must comply with the conditions in Section 3(a) if You Share all or a substantial portion of the contents of the database.

For the avoidance of doubt, this Section 4 supplements and does not replace Your obligations under this Public License where the Licensed Rights include other Copyright and Similar Rights.

Section 5 -- Disclaimer of Warranties and Limitation of Liability.

a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.

b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.

c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.