MASQUELET TECHNIQUE

Dr. Rithvic KevinM.S. Orthopaedic surgery.

Introduction• Bone defects may result from a variety of causes. They may be due to

trauma, bone infection, congenital defects or extensive excision of malignant tumours. Management of bone defects is very challenging. Small size defects can be easily managed by non-vascularized cancellous bonegrafting. The critical size for non-vascularized bone-grafting is 6.0 - 7.0 cm.

• Larger defects require other options. Surgical options available for managing large defects are; vascularized bone-grafts, bone transport, non-vascularized grafts, allografts and fibular pro-tibia grafting.

• Vascularized bonegrafting is technically demanding and require micro vascular surgical skills. The technique is reliable but the donor sites are limited . The advantage is that the bone can be transferred together with soft tissue to cover local soft tissue defect.

• Bone transport is a well established technique for the management of very large bone defects. The procedure has a very high complication rate: up to 80%. Allografts complication rate is also high; may reach 50% .

• The Ilizarov technique is the one commonly used to address intermediate and large bone defects. The technique is very demanding and patient’s cooperation is critical.

• There is no single current technique that is reliably successful in the management of large bone defects.

• The Masquelet technique does offer an alternative and a viable management strategy for large bone defects. The technique was developed in 1986 to address defects larger than 15cm. It was later established that it can successfully address bone defects as large as 25cm. It can be safely used in irradiated or infected areas provided the membrane is formed around the defect to protect and vascularize the bone graft.

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• Masquelet technique is a relative new technique used in the management of large bone defects. It is based on two principles i.e two stages of surgery.

1. The formation of induction membrane:After bone debridement, the defect is filled with bone cement. The cement is kept for a period of eight weeks. This allows the formation of induction membrane.

2. Cancellous bone grafting: After a period of eight weeks, the bone cement is gently removed. The defect is filled with cancellous bone graft .Defects as large as 25cm can be managed using the Masquelet technique.

• INDICATIONS: Dia- and metaphyseal bone defects predominantly of the lower

extremity.• CONTRAINDICATIONS: Intraarticular bone defects, persisting osteomyelitis, insufficient soft

tissue coverage in the region of the bone defect, osteoporosis.

Surgical technique The first step in this technique is the formation of induction membrane. It forms around the bone cement. The membrane serves a very critical function: protection of cancellous bone graft from the body’s immune system. This prevents cancellous bone resorption.

Experimental work has indicated that the induction membrane is not inert. It is a living tissue that plays an important role in bone healing or union.

The first stage in Masquelet’s technique is mechanical: the bone cement provides additional support to the limb and maintain the defect. The primary stability is usually provided by an external fixator. Intramedullary device may also be used as a primary stabilizer. The induction membrane is formed at this stage.

• The second stage is a biological one . The second stage of bone grafting was performed 4–12 weeks after the first surgery. The fracture is approached through the previous incision and careful dissection performed down to the defect. The biomembrane encapsulating the cement spacer is carefully incised. Once exposed, the cement spacer is removed and the biomembrane capsule is irrigated to remove any residual debris. With the defect being open, bone graft was placed to fill the entire defect.

• The defect should be completely filled but not overstuffed. Once the defect is filled, the biomembrane was closed with absorbable suture. The cancellous bone is capable of forming bone even without stress to the bone. But the cancellous bone will resorb if the recipient bed is poorly vascularized.

• It has been demonstrated that periosteal flap wrapped around the cancellous bone exerts a protective effect against bone resorption in muscle tissue.

• The resultant induced membrane was found to be effective in containing the graft materials in situ. It was demonstrated to be an organised pseudosynovial membrane which expressed

Bone morphogenic protein 2 (BMP2) Transforming growth factor- beta (TGFβ) Vascular endothelial growth factor (VEGF) Von Willerbrand factor (vWF) Interleukin 6 (IL-6) and Interleukin 8 (IL-8).

Intra-operative image of PMMA spacer (dot) and capsule (arrow) (A); Suturing the capsule closed after filling with graft material (B).

Post-operative radiographs showingA. PMMA spacer with overlapping edges after the first surgery on the left

B. The graft filled capsule following the second surgery on the right.

A B

Masquelet 2000 •Case series 35 Upper and lower limbs (range: 5– 25 cm) Trauma, infection

•First stage: debridment, external fixation, and cement space

•Second stage at 6–8 weeks with autologous cancellous bone graft + - allograft when required (to a maximum ratio of 1/3)

•Average time to union 8.5 months (6–17 months)

• No recurrence of infection

Tips and tricks for the Masquelet technique

In general, the key for a good outcome is to understand the overall concept of the induced membrane technique:

The pseudosynovial membrane formed around the cement spacer (as a foreign bogy reaction- first stage) acts as a chamber around the bony defect to contain the bone graft and stimulate bone regeneration (second stage)

Tips and tricks for the first stage

• Thorough debridement and irrigation are critical. In patients with infected nonunion or osteomyelitis, this two-stage technique ensures that adequate debridement has been undertaken at the first operation with no evidence of recurrence.•In case of infection (osteitis and/or presence of an IM nail), the canal should be reamed for debridement and irrigated.

•Appropriate fixation of the bone defect is desirable. With the traditional technique, a temporary external fixator is used to provide mechanical stability.The placement of the pins is essential in order to optimise stability, but not to interfere with next incision or future plate position if possible. The length, mechanical axis and the rotation of the extremity should also be maintained. Meticulous pin site care is crucial to minimise the risk of infection.

• In case of other fixation methods (IM nailing or plating), the provided stability should be adequate as it may not be revised at the second stage.

•For optimum membrane induction and better stability of the construct, the cement should be placed inside the canal and over the edges of the bone and should maintain the space of reconstruction.

• The surrounding soft tissue envelope should have adequate blood supply.

•Insertion of cement spacer loaded with antibiotics in case of infected non-union.

•Good soft tissue coverage is essential and free tissue transfer may be required.

•Wound closure must not be under tension.

Tips and tricks for the second stage

Samples for culture must be obtained to exclude persistence of infection in previously infected cases prior to administration of antibiotics intra-operatively.

The membrane must be incised with caution. The cement spacer is removed with a saw or an osteotome with caution not to break the bony edges or to damage the membrane. The IM canal is carefully prepared with hand reamers or a curette and debrided if needed. - All non-vital tissues must be removed.

Autologous bone graft can be obtained from the iliac crest or from the intramedullary canal of the femur (or tibia) using the novel Reamer/Irrigator/Aspirator (RIA) system.

For large defects, autologous bone graft can be augmented with allograft or bone substitutes

Bone graft material can be enhanced with osteoprogenitor cells (from bone marrow aspirate) or with osteoinductive growth factors (commercially available BMPs).

These can be mixed with the autograft prior to filling the defect or they can be placed inside the medullary canal and in the bed of the defect, whilst the autograft can be inserted next for better containment.

The membrane must be closed to ensure that the graft material is contained into the chamber. Adequate mechanical stability must be provided, usually with plate fixation. The plate can be placed either under the membrane or epiperiosteally in an effort to minimally disturb the periosteal blood supply and to assure firm closure of the membrane under the plate.

Soft tissue coverage should be adequate and wound closure should be performed without tension.

(a)A case of an infected non-union in a diabetic patient with previous ORIF of a distal tibial fracture (AP radiograph shown). (b) The plate is exposed over the medial malleolus with an associated skin defect.

During the first stage of the Masquelet technique and after thoroughdebridement, the edges of the bone fragments are healthy with a viable bleeding bed.

Adequate mechanical stability is provided using a temporary external fixator.

For optimum membrane induction and better stability of the construct, the cement should be placed (a) inside the canal (black arrow), and(b) over the edges of the bone (black arrow) and should maintain the space of reconstruction.

During the second stage, the membrane is incised with caution.

An intra-operative picture from another case showing the thickness of the membrane formed over the cement spacer (black arrow).

(a) All non-vital tissues are removed prior to 2nd stage reconstruction, and(b) adequate volume of bone graft is obtained to fill the defect black arrow: cancellous autograft mixed with allograft, dotted arrow: bone substitute, red arrow: BMP-7, white arrow: bone marrow aspirate.

(a) The membrane is closed to ensure that bone graft is contained into the chamber, and (b) adequate mechanical stability is provided with plate fixation; which in this case is placed epiperiosteally