The Masquelet technique for membrane induction and the healing of ovine critical sized segmental defects

Abstract

The healing of critical sized segmental defects is an ongoing clinical problem. No method has achieved pre-eminence. The Masquelet technique is a relatively new innovation involving the induction of a fibrous tissue membrane around the bone defect site taking advantage of the body's foreign body reaction to the presence of a polymethylmethacrylate (PMMA) spacer. The aim of this study was to investigate the properties and characteristics of this induced membrane and its effectiveness when used in conjunction with allograft or an allograft/autograft mix as filler materials in an ovine critical sized defect model. 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). While more new bone growth was evident in the test groups compared to the controls animals at 12 weeks, the volumes were not statistically different and no defects were fully bridged. Of the two graft material groups, the allograft/autograft mix was shown to have a more rapid graft resorption rate than the allograft only group. While the Masquelet technique proved effective in producing a membrane to enclose graft materials, its ability to assist in the healing of critical sized segmental defects when compared to empty controls remained inconclusive.

Figure 1. Intra-operative image of PMMA spacer (dot) and capsule (arrow) (A); Suturing the capsule closed after filling with graft material (B).

Figure 2. Post-operative radiographs showing PMMA spacer with overlapping edges after the first surgery on the left and the graft filled capsule following the second surgery on the right.

Figure 3. MicroCT scans of the defects from the different groups showing residual graft material at 6 weeks (top row), new bone growth at 12 weeks for graft material groups (middle row) and new bone growth at 12 weeks for the empty group (bottom row).

Arrow at 2387 indicates some residual allograft material not yet incorporated into new bone.

Figure 4. H & E sections of the capsule formed as a result of the PMMA spacer.

A: Showing transition of cell orientation deeper into the tissue (400×). B: Showing no basement membrane (1000×). C: Presence of eosinophils (arrows) within the tissue (1000×).

Figure 5. Representative sections of the advancing edge of the callus within the defect at 6 weeks showing fewer remaining graft particles (A) in the allograft/autograft group than the allograft only group (NB = New bone; CO = cortex; FT = Fibrous tissue) (12.5×).

Figure 6. All three 12 week groups where cartilaginous tissues (arrows) can be seen in the two grafted groups as compared to the empty group (12.5×).

Figure 7. Sections showing immunochistochemical expression.

A: BMP2; B: TGBβ; C: VEGF; D: vWF; E: IL-8; F: IL-6.