Obesity (BMI greater than 35)

• Most significant modifiable risk factor
• BMI greater than 40 increases risk 6-fold
• Weight loss of 5-10% significantly reduces risk
• Consider bariatric referral for BMI greater than 45

Diabetes Mellitus

• HbA1c greater than 8% associated with 2-3x increased risk
• Perioperative glucose control critical (target less than 10 mmol/L)
• Preoperative optimization period 3-6 months ideal
• Continuous glucose monitoring perioperatively recommended

Smoking

• Current smoking doubles wound complication risk
• Minimum 4 weeks cessation recommended preoperatively
• 8 weeks cessation optimal for microvascular recovery
• Quitline referral (13 7848) as standard practice

Nutrition

• Albumin less than 3.5 g/dL associated with poor healing
• Prealbumin more sensitive marker of acute nutrition status
• Total lymphocyte count less than 1500 indicates immunocompromise
• Dietitian referral for optimization

Medications

• Corticosteroids: prednisolone greater than 10mg daily increases risk
• Methotrexate: continue through surgery (current evidence)
• Biologics: hold 1-2 dosing cycles preoperatively
• Anticoagulation: increases haematoma risk

Previous Surgery

• Multiple previous incisions increase risk 3-fold
• Prior medial parapatellar approach is preferred for revision
• Avoid crossing previous scars if possible
• Skin bridge less than 7cm increases necrosis risk

Inflammatory Arthropathy

• Rheumatoid arthritis: thin, friable skin
• Psoriatic arthritis: Koebner phenomenon risk
• Systemic lupus: vasculitis and poor healing
• Scleroderma: fibrosis and limited tissue laxity

Peripheral Vascular Disease

• Ankle-brachial index less than 0.9 increases risk
• Absent pedal pulses warrant vascular assessment
• Previous peripheral bypass increases complexity
• Consider vascular surgery input preoperatively

Previous Radiation

• History of soft tissue sarcoma treatment
• Skin changes and fibrosis
• Often requires primary flap coverage
• Discuss with plastic surgery preoperatively

Definition: Involvement of skin and subcutaneous tissue only, without extension to deep fascia or joint.

Types:

• Prolonged drainage: Serous or serosanguinous discharge beyond 5-7 days
• Superficial dehiscence: Partial separation without fascial involvement
• Skin necrosis: Full-thickness skin death, variable extent
• Superficial infection: Cellulitis, suture abscess, superficial SSI

Key Features:

• Intact deep fascia on probing
• No communication with joint space
• Culture typically skin flora
• Systemic symptoms absent or mild

Definition: Extension through deep fascia with potential or actual communication with prosthetic joint.

Types:

• Deep dehiscence: Fascial separation with exposed capsule
• Full-thickness necrosis: Skin, subcutaneous, and fascial involvement
• Deep infection: DAIR criteria met
• Exposed prosthesis: Direct visualization of implant

Key Features:

• Fascial disruption present
• Joint involvement confirmed or suspected
• Systemic inflammatory response common
• Requires surgical intervention

Wound Assessment:

• Extent of erythema (mark and date margins)
• Character of drainage on dressing
• Presence of necrosis (eschar, purple discoloration)
• Wound edge approximation
• Tension on closure
• Evidence of haematoma

Surrounding Skin:

• Tissue turgor and quality
• Previous scars
• Skin grafts or flaps
• Evidence of venous insufficiency

Wound:

• Fluctuance suggesting collection
• Crepitus (concerning for gas-forming organisms)
• Wound edge stability
• Underlying tissue consistency

Joint Assessment:

• Range of motion (guarded suggests effusion/infection)
• Effusion
• Warmth compared to contralateral
• Patella mobility

Wound Probing:

• Sterile probe to assess depth
• Communication with joint (if suspected, do in theatre)
• Tracking along fascial planes

Vascular Assessment:

• Capillary refill
• Peripheral pulses
• Ankle-brachial index if concern

Diabetes Control

• Target HbA1c less than 8% (ideally less than 7%)
• Endocrinology referral for poor control
• Perioperative glucose monitoring protocol
• Insulin sliding scale in hospital

Nutrition

• Albumin target greater than 3.5 g/dL
• Preoperative oral supplements (e.g., Ensure, Resource)
• Consider parenteral nutrition if severely malnourished
• Vitamin C and zinc supplementation

Smoking Cessation

• Minimum 4 weeks preoperative cessation
• Nicotine replacement therapy acceptable
• Quitline referral (13 7848)
• Consider varenicline/bupropion

Weight Optimization

• Target BMI less than 40 for elective surgery
• Dietitian and exercise physiologist referral
• Consider bariatric surgery referral for BMI greater than 50
• 5-10% weight loss reduces risk significantly

Dermatologic Conditions

• Psoriasis: dermatology review, disease control
• Eczema: optimize before surgery
• Chronic wounds: heal before elective surgery
• Venous ulcers: compression, consider vascular input

Hair Removal

• Clippers only, not razor (reduces SSI)
• Day of surgery, not night before
• Avoid if hair not obscuring field

Chlorhexidine Protocol

• 2% chlorhexidine washes for 5 days preoperatively
• Documented reduction in skin colonization
• Avoid mucosal contact
• Alternative for allergy: povidone-iodine

Staphylococcus Decolonization

• Nasal mupirocin if MRSA screen positive
• 5 days preoperatively
• Reduces SSI by 50% in carriers
• Consider chlorhexidine bath in addition

Indications:

• Drainage less than 5 days, decreasing trend
• Superficial erythema responding to elevation
• Normal or minimally elevated inflammatory markers
• No systemic symptoms
• Stable wound appearance

Management:

• Bed rest with leg elevated
• Dressing changes as needed (sterile technique)
• Cease anticoagulation if safe
• Consider compression
• Daily wound review
• Oral antibiotics if superficial infection

Endpoint Criteria:

• Wound dry for 48 hours
• Erythema resolved
• Inflammatory markers normalizing
• Patient afebrile

Failure Criteria (Proceed to Theatre):

• No improvement at 48-72 hours
• Progression of drainage or erythema
• Rising inflammatory markers
• New systemic symptoms

Indications:

• Persistent drainage greater than 5-7 days
• Wound dehiscence (superficial or deep)
• Skin necrosis greater than 2cm
• Suspected haematoma requiring drainage
• Failed conservative management

Procedure Options:

Wound Irrigation and Debridement

• Thorough washout (6-9L saline)
• Debridement of non-viable tissue
• Culture deep tissue samples
• Direct closure if possible
• Consider NPWT if tension

DAIR (if deep infection)

• Polyethylene exchange
• Extended debridement
• Antibiotic treatment per protocol

Postoperative Care:

• Immobilization in extension splint
• Extended antibiotics pending culture
• Daily wound review
• Low threshold for return to theatre

Indications:

• Exposed prosthesis
• Failed previous closure
• Extensive skin necrosis greater than 5cm
• Inadequate local tissue for closure
• Prior radiation field

Flap Options:

Gastrocnemius Flap (Workhorse)

• Medial head most common
• Reliable vascular pedicle
• Good soft tissue bulk
• Can cover proximal 2/3 of TKA wound

Other Local Options

• Soleus flap (distal defects)
• Propeller flaps
• Perforator flaps (ALT, SCIP)

Free Tissue Transfer

• Latissimus dorsi
• ALT (anterolateral thigh)
• Reserved for large defects, failed local flaps

Key Principles:

• Early plastic surgery involvement
• Adequate debridement before coverage
• Healthy recipient bed
• Consider staged approach

Anatomy:

• Two heads: medial and lateral
• Medial head larger, more commonly used
• Vascular pedicle: sural arteries (branches of popliteal)
• Pivot point at musculotendinous junction

Indications:

• Proximal and middle third TKA wounds
• Exposed proximal prosthesis
• Soft tissue defects up to 10x15cm

Technique:

• Medial approach for medial head
• Identify and protect saphenous nerve
• Divide tendon at musculotendinous junction
• Rotate into defect
• Split-thickness skin graft over muscle

Advantages:

• Reliable blood supply
• Good tissue bulk
• Well-established technique
• Can be performed under tourniquet

Limitations:

• Cannot reach distal third of wound
• Cosmetic deficit of calf
• Minor functional impact (minimal weakness)

Soleus Flap

• For middle to distal third defects
• Hemisoleus (medial or lateral) preserves function
• Smaller arc of rotation than gastrocnemius
• Can combine with gastrocnemius

Sartorius Flap

• Limited use around knee
• Small muscle, limited coverage
• Useful for medial defects
• Rarely used for TKA wounds

Propeller Flaps

• Perforator-based rotation
• Useful for smaller defects
• Requires preoperative perforator mapping
• Less robust than muscle flaps

Fasciocutaneous Flaps

• Local advancement or rotation
• Limited by prior incisions
• Useful for superficial defects
• Less reliable in irradiated tissue

Indications:

• Failed local flap options
• Very large defects
• Prior radiation
• Multiple previous surgeries

Common Donor Sites:

Latissimus Dorsi

• Large muscle, reliable pedicle
• Can cover extensive defects
• Donor site well-tolerated
• Long pedicle allows positioning flexibility

ALT (Anterolateral Thigh)

• Fasciocutaneous or myocutaneous
• Less donor morbidity than latissimus
• Good for moderate-sized defects
• Thinner than latissimus

Considerations:

• Microsurgery expertise required
• Longer operative time
• Recipient vessel selection (popliteal, genicular)
• Higher complexity, but excellent salvage option
• Manage expectations