The Role of Macrophages in Early Healing of a Tendon Graft in a Bone Tunnel

• DOI: 10.2106/jbjs.f.00531
• Publication Date: 2008-03-01T11:57:57Z
• Authors: Peyton L. Hays; Sumito Kawamura; Xiang-Hua Deng; Elias Dagher; Kai Mithoefer; Liang Ying; Scott A. Rodeo
• Keywords: Osteoid

Background: Macrophages accumulate following tendon-to-bone repair and may contribute to the formation of a scar-tissue interface rather than reformation normal insertion site. We hypothesized that macrophage depletion lead improved site regeneration, in form "scar-less" healing reactive formation. Methods: One hundred ninety-two Sprague-Dawley rats underwent anterior cruciate ligament reconstruction with use flexor tendon autograft were divided into control group (ninety-six rats) liposomal clodronate-injected rats). Clodronate is bisphosphonate selectively induces apoptosis. Animals clodronate received weekly intraperitoneal injections (1.33 mL/100 g body weight). Rats killed at serial time points from three forty-two days. Immunostaining identified macrophages transforming growth factor-beta (TGF-β) tendon-bone interface. Fibrous width, osteoid formation, collagen fiber continuity evaluated histomorphometry. Serial fluorochrome labeling was used measure mineral apposition rate. Additional for biomechanical testing seven, fourteen, twenty-eight, Results: Liposomal significantly decreased TGF-β accumulation (p < 0.05). Specimens exhibited narrower fibrous tissue between bone all compared specimens controls In group, proceeded an accelerated rate, characterized by enhanced greater degree remodeling bone. There significant increases 0.05) rates among experimental specimens. At days, had respect load failure (mean standard deviation, 13.5 ± 4.2 N 9.7 3.9 N, respectively; p stiffness (mean, 11.5 5.0 N/mm 7.5 3.2 N/mm; Conclusions: Macrophage resulted morphologic properties interface, which we hypothesize are due diminished macrophage-induced production. Clinical Relevance: Techniques modulate inflammation, specifically macrophages, improve enhance structural integrity grafts.