Masquelet Technique (Induced Membrane Technique)

Definition and Introduction

Indications

• Large segmental bone defects (typically >2 cm; classically 4-25 cm or more)
• Post-traumatic bone loss (high-energy fractures, open fractures with bone extrusion)
• Infected nonunion with bone defect (osteomyelitis)
• Chronic osteomyelitis with segmental bone loss
• Tumor resection defects (non-oncological reconstruction)
• Failed bone grafting procedures
• Tibial, femoral, humeral, radial/ulnar, and foot/ankle defects

Defects up to 62 mm have the best outcomes; success rates decline beyond this threshold (Frese et al., 195 patients, ~90% overall success).

Prerequisites (Requirements Before the Procedure)

1. Adequate soft tissue coverage - an excellent soft tissue envelope is mandatory
2. Infection control - active infection must be eradicated before or as part of Stage 1
3. Stable fixation - internal or external
4. Patient optimization - no uncontrolled diabetes, adequate nutrition, non-smoking ideally
5. Adequate vascularity of the limb

Principle / Biological Basis

The Two Stages

Stage 1: Cement Spacer Implantation

1. Thorough debridement - excision of all devitalized/infected bone and soft tissue; achieve clean margins
2. Fracture stabilization - IM nail (diaphyseal defects) or locking plate (metaphyseal defects); external fixator may also be used
3. Fill the defect with a PMMA cement spacer - shaped to match the defect; can be antibiotic-laden (vancomycin + gentamicin achieve 200x the serum antibiotic concentration locally) for infected cases
4. Wound closure over the spacer (or soft tissue coverage flap if required)
5. Systemic antibiotics as per intraoperative cultures

In infected cases, antibiotic-impregnated PMMA (Palacos cement is superior in elution to Simplex cement) achieves extremely high local antibiotic concentrations compared to IV dosing.

Stage 2: Membrane Preservation + Bone Grafting

1. Reopen the wound through the SAME incision
2. Carefully incise the induced membrane longitudinally (do NOT excise or damage it - the membrane must be preserved)
3. Remove the PMMA spacer (the membrane stays intact like a biological "tube")
4. Pack the defect tightly with bone graft - cancellous autograft (iliac crest is gold standard; RIA - Reamer-Irrigator-Aspirator from femur/tibia for large volumes)
5. Close the membrane over the graft
6. Maintain stable fixation
7. Allow recorticalization (typically 3 to 6 months)

Bone Graft Options (Stage 2)

Fixation

• Diaphyseal defects: Locked intramedullary nail (preferred)
• Metaphyseal defects: Locked plate
• Secondary stabilization may be required and is associated with improved outcomes (~34% of cases in Frese's series needed it)

Advantages Over Alternatives

Outcomes

• Masquelet's original series (2000): 35 cases, defects 4-25 cm, successful in all
• Frese et al. (2017): 195 infected defects, 175 patients - ~90% overall success; critical limit of success = 62 mm defect size
• Morris et al. (2017): 12 tibial defects - only 5/12 achieved union; 5 infective complications, 2 required amputation (highlights complexity)
• Upper limb defects: Better tolerated and more successful than lower limb
• Meta-analysis (Singh et al. 2023, PMID 37542493): Compared to vascularized bone grafting in upper extremity - comparable outcomes with Masquelet
• Systematic review (Wakefield et al. 2024, PMID 37921889): IMT vs. distraction osteogenesis for infected tibial non-unions - both viable with different complication profiles

Complications

Special Situations

• Stage 1 uses antibiotic-impregnated PMMA spacer (vancomycin + tobramycin or gentamicin)
• Mandatory: eradicate infection before Stage 2; systemic antibiotics per culture sensitivities
• Membrane itself acts as a barrier to reinfection

• Upper limb: Moderate gaps can be managed by bone shortening; IMT more successful and better tolerated
• Lower limb: More challenging due to weight-bearing demands; higher complication rates

• Masquelet with cement spacer indicated for significant contamination, irreparable talar comminution

Comparison with Bone Transport (Ilizarov)

• Two operations, shorter treatment time, no external frame issues
• Ilizarov requires prolonged frame wearing, pin tract infections are universal, but can manage unlimited defect sizes and simultaneously correct deformity/LLD

Key Points to Remember (Summary Box)

1. Two-stage technique: Stage 1 (PMMA spacer) → wait 4-8 weeks → Stage 2 (graft)
2. PMMA spacer induces a biologically active pseudo-membrane (BMP-2, TGF-beta, VEGF)
3. Membrane is synovial-like, vascular, with few inflammatory cells
4. Growth factors peak at ~4 weeks
5. Stage 2: preserve the membrane, remove cement, pack with cancellous autograft
6. Fixation: IM nail (diaphyseal) or locked plate (metaphyseal)
7. Recorticalization: 3-6 months
8. Works for defects 4-25+ cm; best outcomes below 62 mm
9. Antibiotic spacer achieves 200x local antibiotic concentration vs. IV
10. Excellent soft tissue envelope is mandatory