Orthopaedic Infections😊

Orthopaedic Infections

Suppurative tenosynovitis

 

• M/c Staph Aureus

• Kanavel sign
• ⇒ Pain on passive extension

• Fusiform swelling

• Resembles sausage

• Tenderness along sheath

• Finger held in flexion

Osteomyelitis

General

• Occurs in young children or the elderly due to relatively low immunity.

Routes/Source of Infection (mnemonic: H-D-P-O-S-S)

• Hematogenous (most common)
• From a pre-existing infection.

• Direct

• Post-surgical

• Open fracture

• From septic arthritis

• Soft tissue infection

Etiology

• Staphylococcus aureus: 
• Most common organism causing overall for osteomyelitis:
• Most common causes of osteomyelitis in:
• Acute osteomyelitis
• Chronic osteomyelitis
• Developed countries
• Developing countries
• Immunocompromised (HIV/AIDS)
• Open fracture
• Post-surgical

• Exceptions (Organism related to specific conditions):
• Sickle cell disease patients: Salmonella
• IV drug abusers: Pseudomonas
• Following animal bite: Pasteurella
• Following human bite: Eikenella
• Prolonged parenteral therapy: Fungal organisms

Site of Infection

• Most common site:
• Metaphysis of long bone,
• Especially femur (distal > proximal) > tibia.

• Reasons for metaphyseal involvement:



• Most vascular region of bone.
• Hairpin loop arrangement of blood vessels causes sluggish blood flow.
• Reduced monocytes and macrophages.

Pathophysiology

• Organism reaches metaphysis within <24 hours.

• Systemic manifestations: Fever, pain.

• Abscess formation: After 24 hours.

Sequestrum:

• Hallmark of chronic osteomyelitis.

• Dead bone formed.

Periosteal reaction:

• ~10 days

• → Involucrum
• new bone forming around the pathology

Cloaca 

• break in involucrum

• Pus escape

 

Sinus 

• break in skin

Category	Acute	Subacute	Chronic
Clinical	Fever & pain	ㅤ	Sinus
Pathological	Abscess	ㅤ	Sequestrum
ㅤ	(<2 weeks)	(2-4 weeks)	(>4 weeks)
ㅤ	ㅤ	Brodie's abscess: Lytic lesion with sclerotic margin. Classically vertically oval along tibia length.	Discharging sinus: • Cloacal opening • Dead bone is sequestered - Sequestrum. Radio-opaque (no blood supply, no resorption). Surrounding periosteal reaction - Involucrum (new healing bone).

MRI:

• marrow edema
• earliest changes
• < 24 hours

Bone Scan (Increased accumulation of tracer in infection):

• Indium 111 labelled WBC (Best)

• Technetium 99

• Gallium 67

X-ray:

• Changes after 24 hours

• Earliest X-ray change (within 48 hours):
• Soft tissue lucency/shadow around bone.

• Earliest bony changes on X-ray (7-10 days/2 weeks):
• Periosteal reaction.

Biopsy

• Gold standard.

Treatment

Antibiotics

• 2 weeks parenteral

• f/b 4 weeks oral 

• ± Drainage of abscess.

Complications (Acute Osteomyelitis)

1. Chronic osteomyelitis (most common).

2. Septicemia.

3. Growth disturbance.

4. Septic arthritis:
1. Bone infection to joint.
• Prevented by growth plate.
• Common in:
1. Children <2 years
• before growth plate formation
2. Adults
• after growth plate fusion

Chronic Osteomyelitis

Features

• Sequelae/complication of acute osteomyelitis.

• Persists for >4 weeks following infection.

• Clinical hallmark: Sinus.

Investigations

• X-ray/CT:
• Loss of corticomedullary differentiation.
• Sequestrum.
• Involucrum.
• Cloaca.
• Bone within bone appearance??

Treatment

• Always surgical + antibiotic cover.

• Steps:
1. Sinus tract excision.
2. Sequestrectomy.
3. Curettage till fresh blood is seen (Paprika sign positive).
4. Saucerisation:
1. Debridement to make the mouth wide.

5. Dead space closed with bone graft/cement.

Types of Sequestrum

Complications

1. Pathological fracture
1. (most common):
1. Due to weakened bone.

2. Squamous cell carcinoma
1. Due to neoplastic changes of the sinus tract.

3. Acute exacerbation.

4. Amyloidosis.

Subacute Osteomyelitis (Brodie's Abscess)

• No sinus or sequestrum.

Pathogenesis

• Patient has good immunity.

• Organism has low virulence.

• Infection is contained.

• Penumbra sign: Bony wall forms around infection

Characteristics of Brodie's Abscess

Septic Arthritis

• Surgical emergency:
• Immediate pus removal
• prevent joint destruction.

• More common in children (<5 years) than elderly.

• Most common route: Hematogenous.

Site

• Most common site overall: 
• Knee (ends of bone exposed).

• In infants:
• Hip (Tom Smith's arthritis).

Organism

• Most common organism: Staphylococcus aureus.

• IV drug abusers: Pseudomonas.

• Sexually active individuals: Gonococcus.

Clinical Features (Young child presentation)

• High grade fever.

• Local inflammatory features:
• Swelling, redness.
• Pain:
• Joint effusion stretches the pain-sensitive capsule.
• No movement at joint.

• Joint kept in "position of ease"
• Increased joint volume, decreased pain
• Hip (FABER):
• Flexion,
• Abduction,
• External rotation.
• Knee:
• 5-30° flexion.

Treatment

• Arthrotomy (TOC):
• Irrigation and debridement
• under antibiotic cover.

Complication

• Bony ankylosis:



• End sequela of neglected septic arthritis.

• Pathogenesis:
• Organisms release proteolytic enzymes
• (collagenases, metalloproteinases, elastases) 
• destroy articular cartilage 
• raw ends of bone exposed 
• heal with fusion 
• bony ankylosis.

Other types of ankylosis

Tom Smith's Arthritis

• Septic arthritis of hip in infancy (<1 year).

• Pathogenesis:
• Chondrolysis (cartilage destruction).

• Clinical features:
• Hyper mobility of hip joint → Telescopy test positive.
• Limb shortening.

• Mnemonic: Tom smith nte infant nu Telescope vangi koduth

Tuberculosis (TB)

• Route: Hematogenous.

• Most common site:
• In the body: Lungs.
• Musculoskeletal system:
• Spine TB (Spondylitis) > hip TB arthritis > knee arthritis.
• In spine:
• Dorsolumbar > dorsal > lumbar
• In children:
• Cervical spine

Variants

• Caries sicca:
• TB shoulder
• (Dry/non-exudative TB).

• Spina ventosa:
• TB fingers
• (Filling up of air appearance).

TB HIP

Phemister’s triad: → TB HIP

• Periarticular osteopenia

• Erosions

• Reduced joint space

Treatment

• Synovectomy + joint debridement

• Girdlestone Arthroplasty
• Modification of articular surface
• Excision of affected joint portion
• Reconstruction using vastus lateralis muscle
• Hip becomes Painless and mobile
• But becomes unstable

• Arthrodesis
• Fusion of the joint
• Indication
• Painful fibrous ankylosis
• Result in
• Painless
• Stable hip joint
• Loss of mobility

One liners

TB Spine (Spondylitis): Patterns of Involvement

1. Paradiscal

• most common

• Affects
1. paradiscal areas (bone)
2. intervertebral disc.

2. Central:

• Affects central vertebral body.

3. Anterior/wet/exudative:

• more common in children

• Affects
• anterior vertebral body +
• anterior longitudinal ligament

4. Posterior (Rarest):

1. Affects posterior spinal elements.

Note on TB spine vs spine metastasis on MRI

• Disc involved (Bad disc) → TB spine (Good prognosis).

• Disc spared (Good disc) → metastasis (Bad prognosis).

Clinical Features (TB Spine)

Constitutional features :

• Low grade fever.

• Malaise.

• Night pains.

• Evening rise of temperature.

Local findings :

• Back pain (Earliest symptom).

• Paraspinal spasm/tenderness (Earliest sign):
• Military attitude,
• cautious gait.

• Cold abscess.

• Deformity
• due to vertebral collapse

Spinous process felt prominently on palpation:

• Knuckle: Prominence of 1 spinous process.

• Gibbus: Prominence of 2-3 spinous processes.

• Angular kyphosis: Prominence of >3 spinous processes.

Investigations

• X-ray :
• Disc space narrowing (due to destruction/desiccation of disc):
• Earliest.
• Para vertebral abscess.
• Vertebral destruction.

• MRI (IOC) :
• Disc involved.
• Paradisal disease involving bone and cartilage.

• CT guided biopsy :
• Gold standard.
• Indicated except in
• cold abscess without neurological compromise.

Pott's paraplegia:

• TB spine (Pott's spine) compresses on spinal cord → neurological signs.

• Path nte middilil ethyapo Tailor kk paraplegia ayipoi

Clinical features:

• Early neurological manifestations (UMN findings).
• Ankle clonus/DTR ++
• Extensor Plantar

• Progressive
• neurological deficits
• resistant to Anti TB treatment
• ↑ in Spinal deformity
• ↑ Pulmonary impairment

• Severe Pain

• Cord compression recurrence

• Late: Bowel and bladder involvement.

Treatment

1. Middle path regimen:

• ATT for 18-24 months +

• rest + Taylor's brace.

2. Follow-up:

• Improvement:
• Continue treatment.

• Surgical decompression if
• No improvement/neurological manifestation or 
• worsening/bowel & bladder involvement

Note: Limping child

• Septic arthritis: Fever present (+).

• Perthe's disease: No fever (-).