Masquelet technique: The effect of altering implant material and topography on membrane matrix composition, mechanical and barrier properties in a rat defect model

Abstract

The Masquelet technique is a surgical procedure to regenerate segmental bone defects. The two-phase treatment relies on the production of a vascularized foreign-body membrane to support bone grafts over three times larger than the traditional maximum. Historically, the procedure has always utilized a bone cement spacer to evoke membrane production. However, membrane formation can easily be effected by implant surface properties such as material and topology. This study sought to determine if the membrane's mechanical or barrier properties are affected by changing the spacer material to titanium or roughening the surface finish. Ten-week-old, male Sprague Dawley rats were given an externally stabilized, 6 mm femur defect which was filled with a pre-made spacer of bone cement (PMMA) or titanium (TI) with a smooth (∼1 μm) or roughened (∼8 μm) finish. After 4 weeks of implantation, the membranes were harvested, and the matrix composition, tensile mechanics, shrinkage, and barrier function was assessed. Roughening the spacers resulted in significantly more compliant membranes. TI spacers created membranes that inhibited solute transport more. There were no differences between groups in collagen or elastin distribution. This suggests that different membrane characteristics can be created by altering the spacer surface properties. Surgeons may unknowingly effecting membrane formation via bone cement preparation techniques.

Masquelet Technique: Effects of Spacer Material and Micro-topography on Factor Expression and Bone Regeneration

“…On the other hand, TI created membranes that were better barriers with no effects due to surface roughness. 14 …”

“…Interestingly, the same layer retained the highest amount of solutes greater than 70kDa in our previous study. 14 As such, the NB layer may not only create, but also trap and store, factors for release during stage 2 membrane degradation. Roughening did increase expression of the inflammatory factor, IL6.…”

“…After assuring stable placement, a 6mm defect was created at approximately the bone mid-point, a cylindrical spacer (3.2mmØ × 6mm) was placed in the defect, and the skin was closed. The spacer was made of either PMMA (PalacosR, Zimmer/Biomet, Warsaw, IN) or grade 5 titanium (McMaster-Carr, Elmhurst, IL) with either a smooth (polished with 1um diamond suspension, Buehler, Lake Bluff, IL) or rough (polished with 2500 grit sandpaper, ~8um, McMaster-Carr) (Figure 1, fabrication and characterization described in detail in 14 ). Four weeks later (28 days), animals were either euthanized for stage 1 bone formation and membrane studies or underwent the second grafting surgery (Figure 2).…”

“…particles greater than 70kDa). 14 Membrane compliancy may odulate progenitor cell differentiation and mature cell behavior, 26,30 while improved barrier properties would directly affect cellular migration and biochemical movement between the defect and muscle compartments. Both studies suggest that the membrane can be altered by spacer characteristics, yet neither established whether this affects the second stage bone regeneration.…”

Impaired bone healing following treatment of established nonunion correlates with serum cytokine expression

“…The induced vascularized membrane that forms has been demonstrated to secrete many potent growth factors such as VEGF, TGFβ1, and BMP‐2 and can also prevent resorption of bone grafts . In addition, the membrane properties can be tuned by changing the spacer material used . However, complications such as nonunion still occur in 18–29% of cases treated with Masquelet, highlighting the need to better understand the biological factors that lead to poor bone healing.…”