Chronic

Management PrinciplesFemoral Osteomyelitis

 

Stage the infection, the host & the management 

 

1.  Stage host / maximise healing potential

2.  Stage infection / MCS / sensitivities

3.  Debride all infected bone and ST

4.  Stabilise skeleton

5.  Eliminate dead space

6.  Soft tissue coverage

7.  Eradicate infection

8.  Deal with bone loss / obtain union

 

Aetiology

 

1.  Secondary to acute osteomyelitis

 

2.  Post traumatic

- usually following open fracture

- tibia most common

 

3.  Post operative

- usually after implantation of prosthesis

- ORIF, total joint replacement

 

Cierny Classification

 

Anatomic

Host

Clinical

 

1. Anatomic

 

Type 1 / Medullary Osteomyelitis

- nidus is endosteal

 

Type 2 / Superficial Osteomyelitis

- secondary soft tissue breakdown

- infected cortex due to soft tissue defect

 

Type 3 / Localised Cortical & Medullary Osteomyelitis 

- well marginated sequestration of cortical bone

- entire lesion can be excised without causing instability

 

Type 4 / Diffuse Cortical & Medullary Osteomyelitis

- involves entire segment bone

- unstable pre or post debridement

- infected non union

 

2. Host

 

Type A / Healthy

- good systemic defences

- good local vascularity and a normal physiologic response to infection and surgery

 

Type B / Compromised

- either local, systemic, or combined deficiency in wound healing and infection response

 

Type C / Not a surgical candidate 

- requires suppressive or no treatment

- has minimal disability

- or for whom the treatment or results of treatment are more compromising than the disability caused by the disease itself

 

3. Clinical 

 

I    Simple dead space & simple closure

II   No dead space & complex closure

III  Simple stabilisations with complex dead space & closure

IV  Complex stabilisations / closure / dead space

 

Pathology

 

1.  Bone erosion

 

2.  Cortical & subperiosteal new bone formation

- cavities containing pus & sequestra

- surrounded by areas of sclerosis / reactive new bone

 

3.  Soft tissue

- overlying soft tissue is usually indurated, puckered & adherent to bone

- often sinus connecting lesion to skin

 

Complications

 

Pathological fracture

- 2° bone destruction & brittleness

 

Malignant transformation ~ 1%

- sarcoma

- sinus epithelioid ca

 

Clinical Features

 

Recurrent flares

- pain & fever

- redness / tenderness

 

Discharging sinus

 

X-ray

 

Variable amounts of

- patchy lysis with surrounding sclerosis

- ± dense sequestrum

- bone can be deformed

 

Chronic Osteomyelitis Femur APChronic Osteomyelitis Femur Lateral

 

Bone Scan

 

Increased uptake in lesion

 

CT scan

 

Shows bony architecture

 

Extent of bone destruction

- sequestra

- abscess cavities

 

MRI

 

Best to define extent of infection

 

Chronic Ostetomyelitis Femur MRI CoronalChronic Ostetomyelitis Femur MRI Axial

 

Bloods

 

Variable increase ESR & WCC with flares

Repeat MCS / sensitivity changes

 

Management 

 

Concept Type A / B Host

 

Classical / Conventional method

- convert infected draining nonunion to non infected, non draining nonunion

- then obtain union

 

1.  Stage host / maximise healing potential

2.  Stage infection / MCS / sensitivities

3.  Debride all infected bone and ST

4.  Stabilise skeleton

5.  Eliminate dead space

6.  Soft tissue coverage

7.  Eradicate infection

8.  Deal with bone loss / obtain union

 

1.  Host Factors

 

Most important in outcome

- control diabetes

- maximise nutrition

- cease smoking

 

2.  Identify organism

 

M/C/S

 

Microbiology

- most common S aureus ~ 40 %

- 25 % mixed

- Gram negative 35 %

 

3.  Debridement

 

Removal of all dead bone

Treat infection like tumour

- meticulous debridement of necrotic tissue

 

4.  Stabilise

 

Infected non union worst outcome

 

External fixation / Ilizarov excellent management

- gives stability

- eliminates metal at osteomyelitis site

- obtains union

- deals with bone defect

 

Ilizarov Frame

 

5.  Dead Space

 

A.  Antibiotic beads

- useful in cases unable to immediately graft

- can place flaps over the top & later remove beads

- allows staged bone grafting

 

B.  Papineau open cancellous grafting

 

Concept

- leave open

- repeated bone grafting, dressings

- "grow bone up" to fill defect

 

Indications

- defects <4cm

- Type A patients

- stable defect

- subcutaneous bone

 

Timing of grafting 

- depends on appearance of wound 3/52 after initial debridement

- return to OT at 3/52

- if clean --> graft

- if not further debridement

 

C.  Muscle flap

 

6.  Skin Cover

 

Options

 

Usually muscle flap with SSG

- crucial to success

- fills dead space

- delivers blood supply / antibiotics / healing

 

Types

 

A.  Local rotation flap

- gastrocnemius / soleus

- middle or proximal 1/3 tibia

 

B.  Free vascularized flap

- lat dorsi / gracilis

 

Results

 

Smith et al J Plast Reconstr Surg 2006

- 10 year audit of 41 patients with chronic osteomyelitis

- 37 had free flap, remainder local muscle flap

- only 2 recurrences (4.4%) which where successfully treated with redebridement

 

7.  Eradicate infection

 

IV Antibiotics

Repeated debridement

 

8.  Address bony defect

 

Timing

- usually delay 6/52

- let soft tissues settle, eradicate infection

 

Options

 

1.  Autogenous cancellous bone graft

 

2.  Autogenous vascularized

 

3.  Structural allograft

- need elimination of infection

- useful in humerus 

 

4.  Bone Transport

 

Indications

- large defect > 4cm

 

Problems

- high rate of complications

- expertise required

 

Technique

- debride bone

- acute shortening or delayed docking

- proximal metaphyseal corticotomy

 

Type C patients

 

1.  Dress sinus / drain acute abscess / suppressive Abx 

 

2.  Consider amputation