The Effect of Surgical Technique and Spacer Texture on Bone Regeneration: A Caprine Study Using the Masquelet Technique.

Background: The Masquelet-induced-membrane technique is a commonly used method for treating segmental bone defects. However, there are no established clinical standards for management of the induced membrane before grafting.

Questions/purposes: Two clinically based theories were tested in a chronic caprine tibial defect model: (1) a textured spacer that increases the induced-membrane surface area will increase bone regeneration; and (2) surgical scraping to remove a thin tissue layer of the inner induced-membrane surface will enhance bone formation.

Methods: Thirty-two skeletally mature female goats were assigned to four groups: smooth spacer with or without membrane scraping and textured spacer with or without membrane scraping. During an initial surgical procedure (unilateral, left tibia), a defect was created excising bone (5 cm), periosteum (9 cm), and muscle (10 g). Segments initially were stabilized with an intramedullary rod and an antibiotic-impregnated polymethylmethacrylate spacer with a smooth or textured surface. Four weeks later, the spacer was removed and the induced-membrane was either scraped or left intact before bone grafting. Bone formation was assessed using micro-CT (total bone volume in 2.5-cm central defect region) as the primary outcome; radiographs and histologic analysis as secondary outcomes, with the reviewer blinded to the treatment groups of the samples being assessed 12 weeks after grafting. All statistical tests were performed using a linear mixed effects model approach.

Results: Micro-CT analysis showed greater bone formation in defects with scraped induced membrane (mean, 3034.5 mm; median, 1928.0 mm; quartile [Q]1-Q3, 273.3-2921.1 mm) compared with defects with intact induced membrane (mean, 1709.5 mm; median, 473.8 mm; Q1-Q3, 132.2-1272.3 mm; p = 0.034). There was no difference in bone formation between textured spacers (mean, 2405.5 mm; median, 772.7 mm; Q1-Q3, 195.9-2743.8 mm) and smooth spacers (mean, 2473.2 mm; median, 1143.6 mm; Q1-Q3, 230.2-451.1 mm; p = 0.917).

Conclusions: Scraping the induced-membrane surface to remove the innermost layer of the induced-membrane increased bone regeneration. A textured spacer that increased the induced-membrane surface area had no effect on bone regeneration.

Clinical Relevance: Scraping the induced membrane during the second stage of the Masquelet technique may be a rapid and simple means of improving healing of segmental bone defects, which needs to be confirmed clinically.