June 20, 2024

Chronic Osteomyelitis is a bone infection predicted on pre-existing osteonecrosis.

Osteonecrosis usually takes 3 months to establish (separation of sequestrum from parent bone)

Usually mixed organisms

  • S. aureus
  • E. coli
  • S. pyogens
  • Proteus
  • Pseudomonas aeroginosas
  • S. epidermidis (Coagulase-negative staphylococcus) in the presence of implants

Bone infection predicted on pre-existing osteonecrosis. Osteonecrosis usually takes 3 months to establish (separation of sequestrum from parent bone)

Chronic Osteomyelitis
Chronic Osteomyelitis

Sequestrum

Separated (from parent bone) microscopic/ macroscopic necrotic fragment of usually cortical bone surrounded by infected granulation tissue and pus from viable parent bone.

Identified during surgery: Ivory white brittle piece of bone with smooth (pus facing) and rough (granulation tissue) surfaces lying free from parent bone into the cavity

Paprika sign (-)

Sinks in water

Dull note on percussion

Closed Haversian canal on histopathology

Walenkamp Phenomena: Classical history of pain increases to severe and deep tense pain subsiding with pus breakage and temporary healing

Types of Sequestra

According to shape

Pencil likeInfants
Cylindrical/tubularInfants
RingExternal fixator
ConicalAmputation stump
AnnularAmputation stump
CoralliformPerthes

According to consistency

Coke likeTB
FeatherySyphilis
Sand likeTB osteomyelitis in the metaphysics

According to color

BlackFungal, Amputation stump
GreenPseudomonas

Miscellaneous

MuscleVolkmann Ischemic Contracture (VIC)

Involucrum and its importance

Immature, subperiosteal, reactive, living new bone formation around a dead bone

Wall off abscess, surrounds and can merge with holes cloaca through which pus and granulation tissue may pout, pus discharge

Only if 3 walls of sequestrum are seen fully on two perpendicular views: Sequestrectomy be undertaken

Otherwise, pathological fracture occurs which leads to nonunion

Differential diagnosis of involucrum

  • 50 % infants < 6 months age: Bilateral symmetrical thin layer along diaphysis of femur, radius, humerus
  • Hypervitaminosis A
  • Metastatic leukemias
  • Neuroblastomas

Cierny Madar Classification

Anatomical

Stage 1Medullary osteomyelitisEndosteal
Stage 2Superficial osteomyelitisSurface only
Stage 3Localized osteomyelitisFull-thickness cortical involvement and cavitation
Stage 4Diffused osteomyelitisMechanically unstable

Physiological

A HostHealthy
B Host
BS HostSystemic compromise
BL HostLocal compromise
BLS HostLocal and systemic compromise
C HostTreatment worse than the disease

A 1 +++ Host: Young Childrens

Management

Investigations

  • ESR
  • LFT
  • RFT
  • BS
  • Albumin
  • Prealbumin
  • Transferrin
  • Imaging

Sinogram:

Methylene blue dye is injected through the sinus tract: Clinically mark (live tissue stains grey and dead one blue)

Principle for treatment of chronic osteomyelitis

  • Thorough debridement of necrosis tissue and bone
  • Stabilization of bone
  • Obtaining intra-operative culture
  • Dead space management
  • Soft tissue coverage
  • Limb reconstruction
  • Systemic antibiotics treatment

Sequestrectomy and Curettage

Expose infected area of bone and excise all sinus tracks completely

Remove all sequestra, purulent materials, and scared and necrotic tissues

Paprika sign: Active punctate bleeding bone

Tissue obtained at surgical debridement should be sent for culture and pathology studies

Pulsed Lavage:

Irrigation with 10-14 liters of NS using fluid pressure 50-70 pounds/sq in and 800 pulse/min

Management of defects in Chronic Osteomyelitis

Bone Grafting with primary and secondary closure

Open Bone Grafting (Papineau et al)

Management of bone defects in osteomyelitis by bone grafting methods

3 stages:

Stage 1: Debridement and stabilization

  • Thorough debridement of all sequestra and necrotic bone to healthy and viable soft tissue and bone
  • Stabilization by External fixator or IMILN
  • Apply VAC
  • Repeat debridement and VAC changes every 48 to 96 hours until viable tissues are obtained

Stage 2: Grafting

  • Harvest cancellous bone graft from iliac crest/ tibia
  • Pack graft into bony defect: filling to subcutaneous closure
  • Dress with adaptive and VAC sponge
  • Change VAC: 72-96 hours until the wound is covered with healthy granulation tissue
  • Change dressing until graft stabilize

Stage 3: Wound Coverage

  • Apply skin graft and allow the wound to heal by spontaneous epithelization

Polymethylmethylacrylate antibiotics bead chain

Nonbiodegradable molecules deliver antibiotics locally in concentrations that exceed the minimum inhibitory concentration

The local concentration of antibiotics achieved is 200 times higher than the level achieved with systemic antibiotics administration

Antibiotics are leeched from beads into postoperative wound hematoma and secretion, which acts as a transport medium.

A high concentration of antibiotics can be achieved with primary skin closure, if such closure cannot be performed the wound can be covered with water-impermeable dressings (bead pouch techniques)

Suction drain: Not recommended

Antibiotics used are

  • Heat Stable
  • Water-soluble
  • No chemical reaction with cement

Examples:

  • Aminoglycosides (Gentoamycin, Vancomycin, tobramycin)
  • Clindamycin
  • Cefazolin

Short term: Within 10 days

Long-term: Up to 80 days

Permanent implantation of PMMA can be done

Rationale for removal

Local bacteriocidal activity levels last only for 2-4 weeks after placement when all antibiotics have leached out of beads (foreign body remains: acts as a biofilm)

Disadvantages:

  • Required second surgery for removal
  • Local immune Compramise
  • Local MIC active only for 2-4 weeks
  • Acts as a substrate for bacterial in long term-glycocalyx formation

Bead Pouch techniques:

The cavity is filled with antibiotics impregnated beads completely and covered by sterile transparent/lucent adhesive covering to prevent secondary wound infection

Advantages that no dressing is required during this period

Measure between wound excision and definite skin closure

Intramedullary antibiotics cement nails are used for the debridement of long bones which results in instability following debridement.

Biodegradable Antibiotic Delivery System

  • Calcium hydroxyapatite (Up to 12 weeks)
  • CaSO4, CaPO4
  • Poly-D, L-lactide, polyglycolic acid, polylactic acid

Advantages over PMMA

  • The second surgery is not required to remove the implants
  • Better antibiotics release and compatible profile

These beads can be mixed with a variety of available osteoinductive products to fill dead space and acts as an osteoconductive and osteoinductive bone graft substitute

Usually resorbs by weeks after surgery

Classified into

  1. Protein
  2. Bone graft material and substitute
  3. Synthetic polymers

Lautenbach Approach (Closed suction drain)

Success rate: 85%

Radial excision of all avascular and infected tissue followed by close irrigation and suction drainage

Appropriate antibiotics solution in high concentration to allow dead space to be filled by healthy granulation tissue

Advantages

Change in local antibiotics delivery system based on culture obtained from surgical biopsy

Disadvantages

  • Frequent occlusion of the delivery catheter (decrease with streptokinase use)
  • Prolonged hospitalization
  • Risk of secondary contamination

Adjuvant Therapy

  1. Hyperbaric O2 Therapy
  2. Growth factors (BMPs, PRPs: After eradication of infections)
  3. Physical modalities (Pulsed electromagnetic fields, USGS)
  4. Amputation for osteomyelitis (Risk of malignancy (0.2-1.6%)
    • Major nerve paralysis
    • Malignant changes
    • Arterial insufficiency
    • Joint contracture and stiffness

Osteomyelitis in presence of internal fixation

Osteomyelitis inHealed fractureRemove implants
Nonuniting fractures + not providing stability by implantsRemove implants and restabilize
Nonuniting fractures but stable (1-6 weeks)Retain internal fixation
Stabilizing non-united articular fracturesRetain

Femoral infections with IMNs: Exchange nailing

Extensive Pus (+): Antibiotics Nail

Complications of Chronic Osteomyelitis

  • Recurrences and relapses
  • Limb length discrepancy
  • Pathological fractures
  • Septic arthritis
  • Septicemia
  • Joint stiffness
  • Soft tissue abscess formation and cellulitis
  • Soft tissue contractures
  • Amyloidosis
  • Squamous cell carcinomas of the sinus tract