Fungal arthritis

1. High-Yield Summary

Fungal (mycotic) arthritis is an indolent, destructive, and potentially limb-threatening joint infection caused by opportunistic yeasts, dimorphic endemic fungi, or opportunistic filamentous molds. A rigorous diagnostic approach and timely dual-modality treatment are vital for joint preservation and patient survival:

• Diagnostic Latency: Fungal septic arthritis notoriously presents as an insidious, subacute to chronic monarthritis characterized by joint swelling, persistent effusion, and mild to moderate pain with minimal systemic fever; the median diagnostic delay ranges from 8 to 12 weeks, often resulting in preventable chondrolysis and subchondral bone loss.
• Etiologic Profile: Candida species (predominantly Candida albicans and Candida parapsilosis) account for over 75% of osteoarticular fungal infections in hospital and surgical settings, followed by dimorphic fungi (Sporothrix schenckii, Coccidioides, Histoplasma, Blastomyces) and opportunistic molds (Aspergillus, Mucorales).
• Microbiological Gold Standard: Closed or arthroscopic synovial tissue biopsy is substantially superior to synovial fluid aspiration alone (biopsy culture sensitivity 80% to 90% versus 50% for synovial aspirate); cultures must be incubated on fungal media (Sabouraud dextrose agar) for a minimum of 4 to 6 weeks.
• Dual-Modality Management: Eradication requires aggressive, early surgical debridement (arthroscopic or open synovectomy) combined with prolonged, pathogen-directed systemic antifungal pharmacotherapy (minimum 6 weeks for Candida; 12 months or longer for Sporothrix and endemic dimorphic fungi).
• Periprosthetic Mandate: In fungal periprosthetic joint infection (PJI), debridement, antibiotics, and implant retention (DAIR) is associated with an unacceptably high failure rate exceeding 70%; two-stage revision arthroplasty with an antifungal-impregnated polymethylmethacrylate (PMMA) spacer is the definitive standard of care.

2. Anatomy

Understanding the microvascular and macroscopic surgical anatomy of synovial joints is essential for establishing early diagnosis and executing safe, radical surgical debridement:

Synovial Microvasculature & Seed Corridors

The synovial membrane lacks a true epithelial basement membrane. The fenestrated subsynovial capillary plexus permits direct trans-endothelial extravasation of circulating fungal blastospores and hyphae into the synovial fluid during transient or persistent fungemia. Weight-bearing joints with extensive synovial surface areas and rich subchondral vascularity are most frequently involved. The knee is the primary site in over 70% of reported Candida arthritis cases, followed in frequency by the hip, shoulder, ankle, and radiocarpal joint.

Internervous Exposure Corridors

Open surgical synovectomy requires deliberate utilization of true internervous intervals to prevent iatrogenic denervation while providing uncompromised 360-degree joint access:

• Knee Corridors: Medial parapatellar arthrotomy utilizing the interval between the rectus femoris and vastus medialis obliquus (femoral nerve innervation throughout), or a subvastus approach preserving the extensor mechanism. For extensive posterior capsular disease, a separate posteromedial incision posterior to the sartorius and saphenous neurovascular bundle allows evacuation of popliteal synovial cysts and posterior compartment fungal phlegmon.
• Hip Corridors: Anterolateral (Watson-Jones) plane between the tensor fasciae latae (superior gluteal nerve) and gluteus medius (superior gluteal nerve), or the anterior (Smith-Petersen) plane between the tensor fasciae latae (superior gluteal nerve) and sartorius (femoral nerve) to access anterior capsular collections without compromising the posterior abductor musculature.
• Shoulder Corridors: Deltopectoral interval between the deltoid (axillary nerve) and pectoralis major (medial and lateral pectoral nerves), preserving the cephalic vein laterally and protecting the musculocutaneous nerve as it enters the conjoined tendon 5 to 8 cm distal to the coracoid process.
• Wrist & Forearm Corridors: Dorsal approach utilizing the interval between the third and fourth extensor compartments, or a volar flexor tenosynovectomy corridor through the carpal tunnel, directly mobilizing the median nerve to clear necrotizing sporotrichoid or fungal tenosynovitis.

Neurovascular Danger Zones

Aggressive synovectomy involves dissecting adjacent to major neurovascular structures encased in reactive fibrinous tissue:

• Popliteal Corridors (Knee): The popliteal artery, popliteal vein, and tibial nerve lie immediately posterior to the posterior joint capsule. Capsular debridement in this zone must be executed with the knee in 30 to 45 degrees of flexion to relax posterior neurovascular structures, using blunt retractors placed strictly subperiosteally.
• Femoral Neurovascular Triangle (Hip): Distension of the iliopsoas bursa by fungal synovitis (particularly in Coccidioides or Candida infections) can compress the femoral nerve and external iliac/femoral vessels. Anterior capsulotomy must remain lateral to the iliopsoas tendon.
• Quadrangular Space & Axillary Nerve (Shoulder): The axillary nerve courses 5 mm inferior to the glenohumeral capsular insertion. Inferior capsular synovectomy must avoid excessive electrocautery or over-penetration with motorized arthroscopic shavers along the inferior labrum.

3. Pathogenesis

The development of fungal arthritis involves a multi-step sequence encompassing entry, synovial colonization, phenotypic dimorphic switching, biofilm secretion, and enzymatic host tissue destruction:

Portals of Entry & Inoculation Vectors

• Hematogenous Dissemination: The primary mechanism for Candida species, Cryptococcus neoformans, and endemic dimorphic mycoses. In hospitalized patients, central venous catheters, total parenteral nutrition (TPN), prolonged broad-spectrum antibacterial therapy, gastrointestinal perforations, and intravenous drug use provide direct circulatory access. Seeding occurs preferentially at highly perfused metaphyseal and synovial terminal arterioles.
• Direct Exogenous Inoculation: Resulting from penetrating plant or soil trauma (classically thorny vegetation in Sporothrix schenckii), high-energy contaminated open fractures, diagnostic or therapeutic intra-articular corticosteroid injections (especially related to contaminated compounding pharmacy products), and operative contamination during arthroscopy or arthroplasty.
• Contiguous Spread: Extension into the joint space from adjacent fungal osteomyelitis, spondylodiscitis with epidural abscess, or deep paraspinal/pelvic soft tissue fungal phlegmon.

Microstructural & Enzymatic Destruction

Unlike pyogenic bacterial septic arthritis where neutrophil degranulation and bacterial toxins trigger rapid chondrolysis within 48 to 72 hours, fungal arthritis progresses through an indolent, granulomatous destructive cascade:

• Phenotypic Switching & Tissue Invasion: Candida species transition from unicellular oval blastospores to invasive pseudohyphae and true hyphae upon contact with synovial fluid. Hyphal forms express candidalysin (a cytolytic peptide toxin) and secrete aspartyl proteases (SAPs) that digest extracellular matrix fibronectin, laminin, and interstitial collagen.
• Biofilm Matrix Formation: Candida (especially C. parapsilosis and C. albicans) and Aspergillus produce thick, exopolysaccharide-rich extracellular biofilms on bone, devitalized cartilage, and prosthetic metal/polyethylene substrates. Fungi embedded in biofilms exhibit up to 1,000-fold higher minimum inhibitory concentrations (MICs) to azole antifungals, rendering medical therapy ineffective in the presence of retained hardware.
• Granulomatous Chondrolysis: Macrophages, lymphocytes, and epithelioid histiocytes form non-caseating or caseating granulomas in the subsynovium. Fungal-activated synoviocytes release high levels of matrix metalloproteinases (MMP-1, MMP-3, MMP-13), aggrecanases (ADAMTS-4 and ADAMTS-5), and pro-inflammatory mediators (TNF-alpha, IL-1beta, IL-6), degrading articular type II collagen and aggrecan ground substance over weeks to months.

4. Natural History

If untreated or misdiagnosed, fungal arthritis leads to progressive joint destruction and systemic morbidity:

Epidemiology & High-Risk Hosts

Fungal arthritis accounts for approximately 1% to 3% of all septic arthritis cases worldwide, but its relative incidence is increasing in tertiary care centers. High-risk cohorts include solid organ and hematopoietic stem cell transplant recipients, patients with hematologic malignancies, individuals receiving biologic immunosuppressive agents (TNF-alpha inhibitors, JAK inhibitors), patients in intensive care units with indwelling central vascular lines, patients on prolonged total parenteral nutrition, individuals with poorly controlled diabetes mellitus or chronic kidney disease, and intravenous drug users.

Untreated Clinical Course & Long-Term Prognosis

The natural history progresses through distinct phases:

• Early Insidious Phase (0–4 Weeks): Mild, intermittent joint aching and progressive swelling. Synovial hypertrophy begins without marked joint space loss on plain radiography. Often misdiagnosed as an inflammatory arthropathy flare or crystalline disease.
• Destructive Intermediate Phase (4–12 Weeks): Diffuse pannus formation with marginal erosions at the synovial reflections (bare areas of bone). Cartilage loss accelerates, and extensive subchondral bone marrow edema develops.
• End-Stage Phase (>12 Weeks): Full-thickness articular cartilage loss, subchondral bone collapse, fibrous or bony ankylosis, formation of chronic cutaneous sinus tracts with draining fungal discharge, and contiguous osteomyelitis. In immunocompromised patients, untreated joint disease can serve as a persistent nidus for recurrent fungemia, septic shock, and fatal multi-organ failure (mortality rates of 20% to 30% in disseminated candidiasis cohorts).

5. Clinical Presentation

Due to the indolent nature of fungal pathogens, high clinical suspicion is necessary. A thorough history and physical exam can narrow the diagnostic differential:

History

• Symptom Chronology: Chronic or subacute monoarticular joint swelling and aching pain, typically present for several weeks or months before presentation. The absence of acute high fever or intense erythema does not exclude fungal septic arthritis.
• Medical & Hospital Exposures: Recent intensive care unit admission, indwelling central venous catheterization, prolonged broad-spectrum antibacterial administration, parenteral nutrition, or peritoneal dialysis.
• Iatrogenic Injections: History of intra-articular corticosteroid, hyaluronic acid, or biologic injections, especially when multiple injections have failed to provide relief or provoked worsening symptoms.
• Occupational & Environmental Exposure: Rose gardening, floral handling, or landscaping with decaying wood or sphagnum moss (Sporothrix schenckii); residence or travel to the southwestern United States, Mexico, or Central America (Coccidioides); exposure to bird or bat guano in river valleys (Histoplasma).

Physical Examination

Physical exam reveals signs of chronic synovial inflammation:

• Synovial Boggy Effusion: Significant joint distension with a “doughy” or “boggy” proliferative synovial pannus upon palpation, frequently exhibiting mild joint warmth without the dramatic skin rubor typical of acute bacterial pyogenic infections.
• Restricted Terminal Arc of Motion: Guarded motion with terminal range-of-motion pain. Unlike acute bacterial septic arthritis where the patient holds the joint in rigid protective spasm and resists any passive motion, fungal arthritis often preserves moderate degrees of motion during early and intermediate stages.
• Cutaneous Manifestations: Secondary nodules along superficial lymphatic drainage pathways (ascending lymphocutaneous nodules classic for sporotrichosis), erythema nodosum (coccidioidomycosis), or chronic non-healing sinus tracts discharging purulent or serosanguinous material directly over the joint capsule.
• Patellar Ballottement Test: Detection of knee effusion through suprapatellar pouch compression and fluid rebound against the trochlea [Sensitivity 83%, Specificity 76%].
• Log-Roll Test (Hip): Passive internal and external rotation of the supine extended limb eliciting deep groin and anterior hip capsular pain [Sensitivity 88%, Specificity 65%].
• Tendon Sheath Transillumination / Crepitus: Palpation of volar wrist or ankle tenosynovial thickening with active tendon excursion revealing palpable fine crepitus and boggy sheath swelling [Sensitivity 72%, Specificity 84%].

6. Imaging and Diagnostic Studies

Accurate diagnosis requires sequential radiographic, advanced cross-sectional, and laboratory evaluations:

Plain Radiography

Plain radiographs represent the initial imaging modality. While early films may demonstrate only soft tissue swelling and capsular distension, chronic fungal arthritis demonstrates radiographic features that parallel tuberculous arthritis (the classic Phemister’s triad):

• Marked Periarticular Osteopenia: Severe regional demineralization secondary to prolonged hyperemia and disuse.
• Marginal Bony Erosions: Cortical “punched-out” erosions developing at the peripheral synovial reflections (“bare areas”) where intra-articular bone is unprotected by cartilage.
• Relative Preservation of Joint Space: Unlike bacterial infections where chondrolytic enzymes cause rapid joint space collapse, fungal pannus preserves joint space until late in the disease process, followed by rapid chondral collapse.

Magnetic Resonance Imaging (MRI) & Computed Tomography (CT)

Cross-sectional imaging provides detailed visualization of the soft tissue and osseous architecture:

• MRI Characteristics: MRI is the most sensitive imaging modality for evaluating fungal synovitis. Typical findings include massive, nodular synovial proliferation with intermediate to low signal on T1-weighted images, heterogeneous intermediate to high signal on T2-weighted and proton density sequences, and intense, thick, frond-like enhancement following intravenous gadolinium administration. Extensive subchondral bone marrow edema (hypointense T1, hyperintense STIR) and adjacent tenosynovial fluid collections are ubiquitous.
• Computed Tomography (CT): Optimal for delineating cortical breakthrough, subtle subchondral cysts, sequestrum formation, and guiding closed image-directed aspiration or core needle biopsy in deep joints (hip, sacroiliac joint, spine).

Synovial Fluid Analysis & Microbiology

Definitive identification relies on arthrocentesis and tissue biopsy:

• Synovial Fluid Cytology: Synovial fluid is typically turbid, yellow, or serosanguinous. Leukocyte counts range broadly from 10,000 to 100,000 cells/mcL (mean: 25,000 to 50,000 cells/mcL), with polymorphonuclear leukocyte predominance (60% to 85%), although lymphocytic or mononuclear predominance may occur in chronic dimorphic infections.
• Special Staining: Routine Gram staining detects fungi in only 20% to 30% of cases. Specific fungal stains must be immediately requested: Calcofluor white fluorescent stain (binds to chitin and cellulose in fungal cell walls), Gomori methenamine silver (GMS; stains fungal walls black against a green background), and Periodic acid–Schiff (PAS; stains magenta).
• Fungal Culture Protocols: Synovial fluid and multiple tissue specimens must be plated onto Sabouraud dextrose agar, brain-heart infusion agar with chloramphenicol and gentamicin, and blood agar. Inoculations must be incubated at both 25 to 30 degrees Celsius (for mold forms) and 35 to 37 degrees Celsius (for yeast conversion in dimorphic fungi). Cultures must be maintained for at least 4 to 6 weeks before being declared negative.
• Synovial Tissue Biopsy (Gold Standard): Closed percutaneous core needle biopsy or arthroscopic/open synovial biopsy is mandatory when synovial fluid cultures remain negative despite high clinical suspicion. Histopathology demonstrates chronic granulomatous inflammation, epithelioid cells, Langhans giant cells, and encapsulated yeasts, spherules, or branching hyphae. Tissue culture sensitivity is 80% to 90%.
• Serum and Synovial (1,3)-Beta-D-Glucan (BDG): A pan-fungal cell wall polysaccharide marker with high sensitivity for Candida and Aspergillus species (negative in Cryptococcus and Mucorales).
• Galactomannan Antigen: Highly specific for invasive Aspergillus osteoarticular infections.
• Complement Fixation & Immunodiffusion: Critical diagnostic assays for confirming Coccidioides (serum titers > 1:16 indicate disseminated disease) and Histoplasma.
• Metagenomic Next-Generation Sequencing (mNGS): Rapid, culture-independent direct identification of fungal DNA in synovial fluid or biopsy specimens within 24 to 48 hours.

7. Classification

Fungal arthritis is classified based on pathogen taxonomy, clinical transmission vector, and biological behavior, which directly determine the required systemic antifungal regimen and surgical approach:

8. Treatment

Successful management of fungal arthritis requires coordinated multidisciplinary care involving orthopaedic surgery and infectious disease specialists, combining targeted antifungal therapy with radical surgical debridement:

Medical Therapy & Pharmacologic Protocols

Systemic antifungal therapy must be tailored to pathogen identity, species susceptibility profiles, minimum inhibitory concentrations (MICs), and organ-specific drug clearance:

• Candida Septic Arthritis (Fluconazole-Susceptible): Fluconazole 400 mg to 800 mg (6 to 12 mg/kg) IV or oral daily for a minimum of 6 weeks. Oral bioavailability exceeds 90%, providing synovial fluid concentrations equivalent to serum levels.
• Candida Septic Arthritis (Echinocandin Induction): Caspofungin (70 mg loading, then 50 mg daily IV), Micafungin (100 mg daily IV), or Anidulafungin (200 mg loading, then 100 mg daily IV) for critically ill patients or azole-resistant isolates (C. glabrata, C. krusei), followed by step-down to fluconazole or amphotericin B once clinically stabilized.
• Candida Septic Arthritis (Liposomal Amphotericin B): 3 to 5 mg/kg IV daily, reserved for refractory cases or multi-drug resistant isolates with daily nephrotoxicity and electrolyte monitoring.
• Sporotrichosis: Itraconazole 200 mg orally twice daily for a minimum duration of 12 months. For severe joint involvement or systemic dissemination, initiate lipid amphotericin B (3 to 5 mg/kg daily) until clinical remission, then transition to oral itraconazole with serum trough level monitoring.
• Coccidioidomycosis & Histoplasmosis: Fluconazole 400 to 800 mg daily or itraconazole 200 mg two to three times daily for a minimum of 12 months to lifelong suppressive therapy. Severe refractory coccidioidal joint disease may require intra-articular amphotericin B installations (0.5 to 1.5 mg in sterile 5% dextrose water twice weekly).
• Aspergillosis: Voriconazole (loading dose 6 mg/kg IV q12h for two doses, maintenance 4 mg/kg IV q12h, transitioning to 200 mg PO twice daily) for a minimum of 6 to 12 months, with targeted therapeutic drug monitoring (trough 2.0 to 5.5 mcg/mL).

Native Joint Synovectomy Protocols

Antifungal pharmacotherapy alone is rarely curative due to fungal sequestration in avascular necrotic pannus and biofilm formation. Surgical intervention is required:

• Arthroscopic Debridement: Appropriate for early-stage disease without cortical breakthrough or extra-articular extension. Enables complete visualization of anterior, lateral, and medial recesses. High-volume lavage (minimum 9 to 12 liters of normal saline) and motorized synovectomy must clear all fibrinous and necrotic pannus.
• Open Arthrotomy & Radical Synovectomy: The gold standard for chronic, multiloculated, or neglected fungal arthritis, posterior knee capsular involvement, deep hip infections, or fungal tenosynovitis of the hand/wrist. Open exposure permits complete subtotal synovectomy, debridement of subchondral cysts, curettage of osteomyelitic cavities, and placement of temporary local antimicrobial delivery vehicles.

Fungal Periprosthetic Joint Infection (Two-Stage Revision Protocol)

Prosthetic joints infected with fungi require specialized staged protocols to clear surface biofilms:

• Contraindication to DAIR: Debridement, antibiotics, and implant retention (DAIR) should NOT be performed in fungal PJI; eradication rates are inferior to 30%.
• Stage 1 (Explantation & Spacer Placement): Complete extraction of all prosthetic components and polymethylmethacrylate (PMMA) cement. Perform radical synovectomy and osseous debridement. Implant an articulating or static PMMA spacer impregnated with heat-stable antimicrobials. Formulate the cement spacer with amphotericin B deoxycholate (200 mg to 500 mg per 40 g packet of bone cement) or voriconazole (500 mg to 1000 mg per 40 g packet), combined with broad-spectrum antibacterials (e.g., 2 g vancomycin and 2 g tobramycin per packet) due to high rates of co-existing bacterial infection.
• Interim Antifungal Course: Systemic pathogen-targeted antifungal therapy for 6 to 12 weeks. Serially monitor clinical exams, inflammatory markers (ESR, CRP), and repeat joint aspirate (culture, cytology, and fungal markers) off antifungal therapy for 2 to 4 weeks before considering reimplantation.
• Stage 2 (Reimplantation): Performed once all infection criteria are eradicated (typically 3 to 6 months post-explantation). Send multiple frozen sections intraoperatively (absence of acute inflammation defined as <5 PMNs per high-power field in 5 fields). Secure revision implants with antibiotic/antifungal-loaded cement. Continue oral suppressive therapy postoperatively if risk factors for recurrence persist.

Indications & Contraindications

Decision-making parameters for surgical and medical intervention:

• Absolute Indications for Surgical Drainage: Culture-proven or stain-confirmed fungal arthritis; clinical septic arthritis failing to improve after 48 hours of medical therapy; extensive subchondral osteolysis or adjacent abscess formation; any fungal periprosthetic joint infection (mandatory hardware extraction).
• Indications for Open vs. Arthroscopic Approach: Open arthrotomy is indicated when extra-capsular soft tissue extension, sinus tract formation, dense loculations, or contiguous osteomyelitis prevent complete clearance through arthroscopic portals.
• Contraindications: Sole medical therapy without surgical drainage is contraindicated in all native joint infections with persistent effusion and in all prosthetic joint infections. Intra-articular corticosteroid administration is strictly contraindicated in unexplained synovial effusions.

9. Outcome

Published functional outcomes and infection eradication rates depend on early pathogen identification, underlying host immune status, and aggressive surgical execution:

• Native Joint Eradication Rates: In native joint fungal septic arthritis treated with combined surgical debridement and targeted systemic antifungals, overall infection eradication is achieved in 75% to 85% of cases. However, due to diagnostic delays, 30% to 50% of patients experience permanent functional impairment, secondary degenerative osteoarthritis, or joint contracture requiring secondary reconstructive arthroplasty or arthrodesis.
• Prosthetic Joint Infection Eradication: Two-stage revision arthroplasty achieves infection-free survivorship rates between 70% and 85% at long-term follow-up. In contrast, retention of hardware (DAIR) results in treatment failure in over 70% of cases, often necessitating salvage resection arthroplasty (Girdlestone procedure), knee fusion, or limb amputation.
• Patient-Reported Outcome Measures (PROMs): Patients recovering from fungal septic arthritis demonstrate lower mean functional outcome scores compared to those recovering from acute pyogenic bacterial septic arthritis (average Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] pain and physical function scores reflect moderate to severe residual impairment), directly driven by cartilage loss sustained during pre-diagnostic latency.

10. Complications

Complications associated with fungal arthritis span procedural, pharmacologic, and systemic categories:

11. Pearls and Pitfalls

Expert diagnostic and operative pearls can help mitigate clinical errors:

• The “Hold the Cultures” Imperative: Never allow the microbiology laboratory to discard synovial fluid or bone cultures at standard 5 or 7 day incubation intervals. Specifically communicate the clinical suspicion of fungal disease and ensure cultures on Sabouraud dextrose agar are incubated for a full 4 to 6 weeks.
• Always Biopsy the Synovium: Synovial fluid aspiration alone has a false-negative culture rate of nearly 50% in fungal infections. Whenever fungal arthritis is suspected or synovial aspirate reveals high leukocyte counts with negative routine bacterial stains, proceed promptly to closed percutaneous core needle biopsy or arthroscopic synovial biopsy for fungal histopathology and culture.
• Inspect the Eye: Every patient with confirmed or suspected Candida septic arthritis must undergo an urgent dilated fundoscopic ophthalmologic examination to evaluate for Candida endophthalmitis. Inadvertent delay can lead to irreversible retinal detachment and blindness.
• Avoid the Corticosteroid Trap: Administering intra-articular corticosteroid injections into a joint with unexplained, refractory swelling is a major pitfall. Steroid injection impairs local host macrophage defenses, accelerates fungal replication, and converts an indolent synovial process into extensive osteocartilaginous necrosis.
• PJI Hardware Retention is Futile: In fungal periprosthetic joint infection, attempting DAIR out of concern for patient frailty almost uniformly leads to failure. Formulate a definitive two-stage plan with aggressive hardware removal and high-dose antifungal-impregnated cement spacers.

12. Controversy

Several key controversies continue to be debated regarding fungal arthritis management:

• Single-Stage vs. Two-Stage Revision for Fungal PJI: While two-stage revision remains the international standard of care, emerging European protocols propose single-stage exchange arthroplasty using targeted antifungal cement and prolonged systemic therapy in highly selected, non-immunocompromised patients with known pathogen sensitivity. However, current global consensus continues to advocate two-stage protocols due to unacceptably high reinfection risks.
• Antifungal Cement Elution Dynamics: The addition of amphotericin B to PMMA bone cement impairs PMMA mechanical compressive strength if excessive powder is added, and amphotericin B exhibits limited hydrophobic elution from commercial bone cement compared to voriconazole. Optimizing the combination of voriconazole or liposomal amphotericin B with water-soluble aminoglycosides to create porous elution corridors remains an area of active biomechanical research.
• Lifelong Oral Suppressive Therapy: In severely immunocompromised hosts (e.g., solid organ transplant recipients, active hematologic malignancy) who undergo revision arthroplasty for fungal PJI, the necessity and duration of lifelong secondary oral azole prophylaxis (e.g., fluconazole 200 mg daily) must be balanced against risks of cumulative hepatotoxicity, drug interactions, and the emergence of multi-drug resistant fungal strains (such as Candida auris).
• Synovial Fluid Biomarker Reliability: The clinical utility of synovial (1,3)-beta-D-glucan (BDG) and metagenomic next-generation sequencing (mNGS) for guiding early surgical decisions before final culture maturation remains under active validation. Although mNGS provides rapid turnaround, standardizing clinical diagnostic thresholds to differentiate active infection from colonizing or environmental contamination remains challenging.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Bariteau JT, Waryasz GR, McDonnell M et al. Fungal osteomyelitis and septic arthritis. J Am Acad Orthop Surg. 2014. doi:10.5435/JAAOS-22-06-390 [Level V: Instructional Course Lecture / Expert Review]
• Pappas PG, Kauffman CA, Andes DR et al. Executive Summary: Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016. doi:10.1093/cid/civ1194 [Level V: Clinical Practice Guideline Consensus]
• Gamaletsou MN, Rammaert B, Bueno MA et al. Candida Arthritis: Analysis of 112 Pediatric and Adult Cases. Open Forum Infect Dis. 2016. doi:10.1093/ofid/ofv207 [Level IV: Multicenter Retrospective Cohort Study]
• Kauffman CA, Bustamante B, Chapman SW et al. Clinical practice guidelines for the management of sporotrichosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis. 2007. doi:10.1086/522765 [Level V: Clinical Practice Guideline Consensus]
• Rattanaprichavej P, Laoruengthana A, Chinwatanawongwan B et al. Comparative Effects of Treatment Strategies for Fungal Periprosthetic Joint Infection: A Systematic Review and Network Meta-Analysis. J Arthroplasty. 2026. doi:10.1016/j.arth.2026.09.013 [Level I: Systematic Review and Network Meta-Analysis]

15. Master Class Pro-Tip

When approaching suspected fungal septic arthritis or fungal periprosthetic joint infection, remember that time is your greatest adversary. The indolent, ‘cold’ presentation frequently lures clinicians into prolonged diagnostic wandering while irreversible chondrolysis progresses. Immediately send synovial fluid and core synovial tissue biopsies for Calcofluor white staining and fungal cultures held for a minimum of 4 to 6 weeks, and order an urgent dilated ophthalmologic exam to rule out occult endophthalmitis. In periprosthetic cases, resist the temptation to perform DAIR; complete hardware explantation with radical synovectomy and an antifungal-impregnated cement spacer (amphotericin B or voriconazole combined with broad-spectrum antibacterials) in a disciplined two-stage protocol is the only reliable pathway to infection eradication and limb salvage.

Master Class Surgical Pearl: Fungal Septic Arthritis