Diaphyseal defects too long to be bridged by cancellous bone graft require complex reconstruction. Distraction osteogenesis requires specialized equipment, has a steep learning curve, and is plagued by attendant pin-site complications and nonunion1,2. Vascularized bone, such as from the fibula, requires microsurgical anastomoses (free), or is limited by pedicle length (pedicled), and has attendant donor-site morbidity (both free and pedicled)1,3.
The French technique of bone-grafting within induced membranes, otherwise known as the Masquelet technique, offers a viable alternative with minimal complications4,5. In this technique, a cement spacer is placed in a posttraumatic bone defect. Its presence serves a twofold function of preventing fibrous ingrowth into the bone gap, and inducing the formation of specialized tissue or so-called induced membranes around it. Bone graft placed within this tube of induced membranes incorporates into functioning bone.
We present the case of a patient with diaphyseal bone loss and the case of a patient with epimetaphyseal bone loss, both with ongoing bacterial contamination, successfully treated by this procedure. Both patients were informed that data concerning the case would be submitted for publication, and they consented.
The management of segmental long-bone defects is a challenge. The literature has described many techniques, but each is fraught with specific difficulties1. Autologous nonvascularized cancellous bone graft possesses superior osteoconductivity and osteoinductivity, but its use is confined to small defects. Graft incorporation is slow and unreliable, and nonunion may arise when the grafted host bed is of doubtful vascularity.
Larger defects are amenable to vascularized bone transfer3 or distraction osteogenesis2. The latter technique requires specialized training and equipment, and is often associated with complications including pin-track infections and nonunion. The transfer of vascularized bone from the rib, fibula, or iliac crest is another widely utilized technique used to bridge larger defects. Besides being limited by pedicle length (pedicled grafts) and the need for microsurgical anastomoses (free grafts), donor-site morbidity has been reported to occur in up to 19% of patients managed with vascularized fibular grafts1,7. In addition, both approaches require a long treatment time, leading to disuse atrophy of the involved limb, psychological stress, and loss of income1,8.
Describing the Masquelet technique, Pelissier et al. proposed the use of a combination of induced membranes and cancellous autografts to bridge diaphyseal defects of up to 25 cm in length4,5. In this technique, a methylmethacrylate cement spacer induces formation of a membrane, creating a pocket for subsequent grafting. Pelissier et al. determined that these membranes possessed a rich capillary network and have high concentrations of growth factors (vascular endothelial growth factor and transforming growth factor-beta-1) and osteoinductive factors (bone morphogenetic protein-2)5. Immunohistochemical studies on induced membranes in a sheep model by Viateau et al.9 established the presence of cells expressing transcription factor CBFA1, and type-I collagen rich extracellular matrix, with few macrophages. With the above characteristics, the membranous pocket prevents resorption of the contained graft, acts as a barrier to outward diffusion of growth and osteoinductive factors, and provides a source of stem cells and vascular cells supporting revascularization and osseous consolidation5.
In this report, we describe the cases of the first two patients in our experience with this technique. In both patients, the presence of induced membranes was documented by visual inspection of the fracture gap and its surrounding tissues on removal of the cement spacer; there was no histological confirmation of the presence of these membranes.
The cases of these two patients are illustrative of the Masquelet technique, with a few variations. In both patients, infection was present in the region of segmental bone loss. In the first patient (Case 1), impregnating the cement spacer with an antibiotic targeted at the contaminating pathogens facilitated graft-bed sterilization. This is an extension of the existing concept of antibiotic-impregnated beads in the management of dead space in segmental bone defects10, and the use of an antibiotic in this fashion has previously been described for septic nonunion11 and chronic osteomyelitis12,13. Admixing antibiotic into the cement mixture compromises compressive strength14; however, this was not an issue as the cement block serves only as a spacer to obviate dead space, preventing fibrous ingrowth, while directly inducing membrane formation. The case of this patient also demonstrates that the Masquelet concept can be applied successfully with intramedullary nail fixation, which differs from the original technique with use of external fixation4.
For the second patient (Case 2), bone loss was of epimetaphyseal origin. Management of complex tibial pilon fractures is challenging, with early ankle osteoarthritis often being the end result15, and primary ankle fusion is an option for the salvage of fractures that are not reconstructible16. Bone-grafting within the induced membrane allows for graft preservation in an area of poor vascularity although, in this patient, bone-grafting had to be performed twice. After the initial Masquelet procedure, the large defect had been reduced to a simple nonunion, which was amenable to conventional bone-grafting.
The technique of bone-grafting within induced membranes does not require specialized equipment, it can be performed easily and by surgeons with varying experience and capability, and it is applicable to patients with bone loss of epiphyseal, metaphyseal, or diaphyseal origin.