Septic Arthritis In Children

Septic arthritis is bacterial infection of a synovial joint and is an orthopaedic emergency. Rapid bacterial proliferation and intense inflammation can destroy articular cartilage within days, particularly in the hip.

Staphylococcus aureus is the major pathogen. Kingella kingae is important in toddlers, while pneumococcus, group A Streptococcus and Gram negative organisms occur less commonly. Adjacent osteomyelitis may coexist.

The classic presentation is acute painful restriction of a single joint with fever.

• Severe joint pain
• Refusal to move the limb
• Limp or complete refusal to weight bear
• Joint swelling, warmth and effusion
• Marked pain on passive movement
• Hip held flexed, abducted and externally rotated when the hip is involved

Infants may present only with irritability, pseudoparalysis or poor feeding.

Septic arthritis should be considered urgently in any febrile child who refuses to move a joint.

• Obtain blood cultures, FBC, CRP and ESR.

• Ultrasound is useful for detecting joint effusion, particularly at the hip, but cannot distinguish sterile from infected fluid.

• Joint aspiration is central. Send synovial fluid for Gram stain, cell count, differential, culture and susceptibility; molecular testing can increase yield, particularly for K. kingae.

• MRI is valuable when adjacent osteomyelitis, deep infection or pelvic disease is suspected.

• A high synovial white cell count with neutrophil predominance strongly supports bacterial arthritis, but no single numerical threshold completely confirms or excludes infection.

• Obtain cultures and begin IV antibiotics promptly. Empirical treatment must cover S. aureus.

• Where MRSA prevalence is low, cefazolin 50 mg/kg IV every 8 hours, maximum 2 g per dose, is appropriate.

• Where MRSA is significant, clindamycin 10 to 13 mg/kg IV every 8 hours, maximum 900 mg per dose, can be used if susceptibility is reliable; otherwise use vancomycin with therapeutic drug monitoring.

• Drainage is required for most substantial purulent joint infections, by repeated aspiration, arthroscopic washout or open drainage depending on joint, disease severity and local expertise.

• Switch to appropriate oral therapy when fever resolves, joint function clearly improves and CRP is falling.

• Primary bacterial arthritis without adjacent osteomyelitis may require only 10 to 14 days total therapy when source control is adequate and clinical and CRP response is rapid. Slower response or inadequate drainage generally requires 21 to 28 days.

Tendon Rupture

Tendon rupture is partial or complete structural failure of a tendon, producing loss of normal force transmission from muscle to bone.

Rupture may be:

Acute traumatic
Degenerative
Spontaneous through diseased tendon
Open tendon laceration

Clinically, the most useful distinctions are:

Partial versus complete

A partial rupture retains some continuity and function.

A complete rupture produces full structural discontinuity.

Acute versus chronic

Acute tears have relatively mobile tendon ends and better potential for direct primary repair.

Chronic neglected tears progressively develop:

Retraction
Adhesion
Muscle atrophy
Fatty degeneration
Tendon gap

and may require reconstruction rather than direct repair.

Risk factors for spontaneous or low energy rupture include:

Increasing age
Chronic tendinopathy
Diabetes
Renal disease
Hyperparathyroidism
Systemic inflammatory disease
Fluoroquinolone exposure
Systemic or local corticosteroid exposure
Previous tendon injury

Patients often describe:

Sudden snap or pop
Acute pain
Immediate weakness
Loss of a previously normal movement
Palpable tendon defect

The examination must assess function, not merely tenderness.

Examples:

Quadriceps tendon

Loss of active knee extension and inability to perform straight leg raise.

Patellar tendon

Same extensor mechanism failure, usually with a high riding patella.

Distal biceps

Loss of flexion strength and particularly supination strength.

Triceps

Weak or absent resisted elbow extension.

Achilles

Loss of plantar flexion power with positive Thompson test.

Partial ruptures can preserve enough function to make the diagnosis less obvious.

Management depends heavily on the tendon involved.

Partial rupture

A partial tear with preserved function can often be treated with:

Relative rest
Short protective immobilisation where necessary
Progressive physiotherapy
Correction of precipitating factors

Progress loading according to pain and function.

Failure to regain strength or progression to complete rupture requires reassessment.

Complete rupture

A complete rupture causing major functional loss usually requires either:

Structured functional rehabilitation

Surgical repair

depending on the tendon.

Not all complete tendon ruptures require surgery. Acute Achilles rupture is the important example where modern functional nonoperative treatment can produce results close to operative repair in appropriately selected patients.

Extensor mechanism rupture

Complete quadriceps or patellar tendon rupture with loss of active knee extension generally requires early surgical repair.

Repair is easier during the first several weeks before:

Tendon retraction
Scar formation
Patellar migration
Quadriceps shortening

Acutely, use strong nonabsorbable or high strength sutures with:

Transosseous tunnels

Suture anchors

according to tear location.

Chronic extensor mechanism disruption may require:

V Y advancement
Tendon autograft
Allograft
Synthetic augmentation

Distal biceps rupture

A complete distal biceps rupture in an active patient generally benefits from repair because nonoperative treatment leaves substantial loss of supination strength.

Repair is ideally performed during the early period before major tendon retraction and scarring.

Older low demand patients may accept nonoperative treatment.

Open tendon injury

Open laceration requires:

Wound assessment
Irrigation and debridement when contaminated
Neurovascular examination
Primary tendon repair when tissue is suitable

A contaminated open tendon injury should not be closed around devitalised tissue merely to obtain immediate repair.

Rehabilitation principle

Tendon healing requires protection from excessive tensile load but also benefits from controlled progressive mechanical stimulation.

Prolonged rigid immobilisation causes:

Adhesion
Joint stiffness
Muscle atrophy
Reduced tendon mechanical quality

Rehabilitation should therefore progress from protected motion to controlled strengthening according to the repaired tendon and strength of the construct.

Septic Arthritis In Children

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management