Septic Arthritis — Arthroscopic Washout and Debridement

Indications. Arthroscopic washout and debridement is the surgical source-control operation for a native joint with confirmed or strongly suspected pyogenic (bacterial) septic arthritis. Absolute indications

• Confirmed or strongly suspected septic arthritis on clinical, laboratory and imaging grounds — a hot, swollen, painful joint with systemic features.
• Synovial fluid white cell count greater than 50,000 per microlitre with a neutrophil predominance, or a positive Gram stain.
• Failed medical management — persistent effusion or rising inflammatory markers after 48 hours of appropriate intravenous antibiotics.
• Septic arthritis of a joint where arthroscopy gives reliable access (knee, shoulder, ankle). Relative indications
• Culture-negative septic arthritis with high clinical suspicion and failure to improve on empiric antibiotics.
• An immunocompromised patient with atypical organisms or polymicrobial infection requiring aggressive source control.
• Concomitant osteomyelitis requiring combined arthroscopic and open debridement. Contraindications
• Absolute: life-threatening sepsis requiring immediate stabilisation before any surgical intervention; inability to tolerate anaesthesia (rare — most patients can be managed under regional or general anaesthesia).
• Relative: a very early presentation (less than 6 hours) with minimal effusion in a stable patient, where a trial of aspiration plus antibiotics is reasonable but with a low threshold for washout; known crystal arthropathy with superimposed infection still requires washout if bacterial infection is confirmed. Why this is an emergency. Bacterial proteases (staphylococcal and streptococcal) degrade cartilage proteoglycans within 6-12 hours, and irreversible chondrocyte death begins by 24 hours. Every hour of delay increases the risk of secondary osteoarthritis by approximately 5-7 percent. Multiple retrospective series and one systematic review show that delay from symptom onset to surgical washout of greater than 24 hours is associated with a 2- to 3-fold increase in permanent joint damage and secondary osteoarthritis. The practical target in most trauma units is aspiration within 1-2 hours of arrival and washout within 6 hours.

Arthroscopic versus open washout — the decision. For the knee, shoulder and ankle, arthroscopic washout achieves equivalent infection eradication to open arthrotomy while preserving range of motion and reducing morbidity. Adult hip septic arthritis can be managed arthroscopically in selected cases by experienced surgeons, but open drainage remains the default in most centres.

When open is mandatory. Open arthrotomy is required whenever arthroscopic access is inadequate — most importantly the hip in a child, where arthroscopy cannot reliably decompress the deep acetabular fossa or protect the femoral head blood supply. Urgent open anterior drainage is the standard of care for paediatric hip septic arthritis (see The Operation for the technique). Consent. Discuss the risk of incomplete clearance requiring a repeat washout or open arthrotomy, neurovascular injury from portal placement, iatrogenic chondral damage, persistent infection, secondary osteoarthritis, and post-operative stiffness. Setup and positioning. | Joint | Position | Notes | |-------|----------|-------| | Knee | Supine, leg holder or free leg | Tourniquet optional — inflate only if visualisation is poor | | Shoulder | Beach-chair or lateral decubitus | Arm in traction | | Ankle | Supine, bump under ipsilateral hip | Tourniquet standard | | Hip (adult) | Supine on a traction table | Perineal post well padded | Anaesthesia is regional (spinal or peripheral nerve block) plus sedation, or general anaesthesia. Do not delay surgery to chase a regional-only technique in a septic patient.

The goal is to establish safe access to the joint, evacuate the pus, perform a near-total synovectomy removing every fibrinous loculation, irrigate copiously, and obtain tissue for culture — then plan a second look. The knee is the canonical case and is laid out step by step below; shoulder, ankle and hip portal variations follow, then the structures at risk, and finally open drainage for the cases arthroscopy cannot solve.

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Shoulder — portal variations. Establish the posterior viewing portal first (2 cm inferior and 1 cm medial to the posterolateral acromion corner), perform diagnostic glenohumeral arthroscopy, then add an anterior portal (lateral to the coracoid tip) and a lateral portal (2 cm lateral to the acromion edge) for subacromial access. Irrigate the glenohumeral joint with 6-9 litres and perform synovectomy of the capsule, the biceps tendon sheath and the subscapularis recess — hidden recesses that must be specifically inspected. Infection frequently tracks into the subacromial bursa via the rotator interval or through a cuff tear, so switch to the subacromial space and perform a complete bursectomy and irrigation, inspecting the rotator cuff from both the articular and bursal sides. Add an anterolateral portal for access to the anterior-inferior capsule and axillary recess when loculations persist. Ankle — portal variations. Use anteromedial (medial to tibialis anterior) and anterolateral (lateral to peroneus tertius) portals, with a posterolateral portal (lateral to the Achilles tendon, 1 cm proximal to the joint line) for posterior ankle joint and subtalar access when indicated. Hip (adult) — portal variations. Use an anterior portal (2-3 cm distal and lateral to the anterior superior iliac spine, over the sartorius-tensor fascia lata interval) and an anterolateral portal (2 cm distal to the greater trochanter tip, in line with the femoral shaft) on a traction table; the perineal post must be well padded. Open drainage is preferred in most centres.

Open drainage — when arthroscopy is not the answer Paediatric hip septic arthritis is an absolute indication for open drainage. The paediatric hip has a thick capsule and a small joint volume, the medial femoral circumflex artery runs intracapsular within the surgical field, and the deep acetabular fossa and ligamentum teres cannot be adequately accessed arthroscopically. Standard teaching and registry data mandate urgent open anterior arthrotomy (Smith-Petersen, occasionally Watson-Jones) for all confirmed or strongly suspected paediatric hip septic arthritis; delay risks avascular necrosis of the femoral head. Open technique (Smith-Petersen anterior approach):

1. Anterior approach between sartorius and tensor fascia lata.
2. T-shaped or longitudinal capsulotomy.
3. Evacuation of pus, synovectomy and thorough lavage.
4. Capsular closure over a drain, then skin closure.
5. Postoperative traction or an abduction pillow for 2-3 weeks.
6. Intravenous antibiotics for 3-4 weeks followed by an oral step-down. Open arthrotomy is also the fallback for any joint where loculations cannot be adequately cleared arthroscopically at index or at a planned second look.

Immediate post-operative (day 0-3)

• Continue intravenous antibiotics — empiric, then targeted once organism and sensitivities are known.
• Drain removal at 24-48 hours, or when output is less than 30 mL per 24 hours.
• Immobilise in a sling (shoulder) or brace (knee in extension) for comfort only — encourage gentle active-assisted range of motion from day 1.
• Daily clinical review and inflammatory marker monitoring (CRP, white cell count). Early rehabilitation (week 1-6)
• Formal physiotherapy from day 2-3: active-assisted then active range of motion, progressing to strengthening.
• Weight-bearing as tolerated for lower-limb joints.
• Repeat inflammatory markers at day 3, 7 and 14.
• Plan a second-look arthroscopy at 48-72 hours if the clinical or biochemical response is inadequate. Return to function
• Hospital discharge when the patient is afebrile, tolerating oral antibiotics, and inflammatory markers are trending down — typically day 5-9.
• Return to desk work at 2-4 weeks; manual work at 6-12 weeks.
• Full sporting activity at 3-6 months once the infection is cleared and strength is restored. Repeat washout — plan it proactively. A repeat arthroscopic washout at 48-72 hours is required in 30-50 percent of cases and is associated with improved outcomes compared with a single washout. Do not wait for clinical deterioration: if the patient remains febrile or the CRP is not falling by 48-72 hours, take them back. Antibiotic strategy. Start empiric intravenous therapy immediately after cultures are obtained — vancomycin plus ceftriaxone (or piperacillin-tazobactam in a high-risk patient) — and de-escalate at 48-72 hours once the organism and sensitivities are known. Typical duration is 2-4 weeks intravenous followed by an oral step-down, for a total of 4-6 weeks in most immunocompetent patients. Blood cultures are positive in 30-50 percent of cases. Hold immunosuppressants (methotrexate, biologics) during the acute phase and restart only after infection clearance, in discussion with rheumatology. Special populations — tailor the cover

Complications

Pathophysiology — why hours matter. In septic arthritis the infecting organism multiplies within the joint and triggers an intense neutrophilic inflammatory response. Bacterial proteases — particularly staphylococcal and streptococcal enzymes — directly degrade articular cartilage proteoglycans within 6-12 hours, and the inflammatory milieu drives irreversible chondrocyte death beginning by 24 hours. Raised intracapsular pressure further compromises periarticular blood supply. This is why every hour of delay increases the risk of secondary osteoarthritis by approximately 5-7 percent, and why delay beyond 24 hours roughly doubles the rate of permanent joint damage. Microbiology. Staphylococcus aureus is the most common cause across age groups; Streptococcus species and, in young sexually active adults, Neisseria gonorrhoeae are also important. Haemophilus influenzae historically dominated young children but is now rare in vaccinated populations. The organism spectrum broadens in high-risk hosts: intravenous drug users, the immunocompromised and patients with penetrating trauma or contiguous osteomyelitis have higher rates of Gram-negative organisms (notably Pseudomonas), anaerobes and polymicrobial infection, and fungal or mycobacterial organisms must be considered — warranting extended cultures and broader empiric cover. Why arthroscopy, when feasible. For the knee, shoulder and ankle, comparative cohort evidence shows arthroscopic washout achieves infection control equivalent to open arthrotomy (85-96 percent eradication), with better final range of motion, lower morbidity and a shorter hospital stay. The hip is the exception: the paediatric hip mandates open drainage, and in most centres the adult hip is also managed by open arthrotomy unless an experienced hip-arthroscopy service is available. The repeat-washout principle. The Gachter/Stutz protocol of staged repeat arthroscopic lavage at 48-72 hour intervals until clearance — an average of 2.3 lavages — eradicated infection in 93 percent of cases and reduced the need for open arthrotomy to less than 10 percent. This is the basis for planning, not merely accepting, a second look.