Paper # 216: The Effect of Organic Silicon Injection on Achilles Tendon Healing in Rats

Abstract

Organic silicon compounds can affect the activity of fibroblasts and growth factor production but the exact mechanisms are unknown. The purpose of this study was to investigate the effect of organic silicon (monomethyltrisilanol) on healing in a rat Achilles tendon healing model. Organic silicon compounds can affect the activity of fibroblasts and growth factor production but the exact mechanisms are unknown. The purpose of this study was to investigate the effect of organic silicon (monomethyltrisilanol) on healing in a rat Achilles tendon healing model. We hypothese that organic silicon would enhance the healing process in achilles tendon repairs. Twenty-one female Wistar-Albino rats weighting between 350 and 450 grams were used for this study. All left legs prepared as silicon group (21 tendons) and all right legs prepared as control group (21 tendons). Rats were randomly divided into three groups for histological assessment at day 20 (7 rats), biomechanical testing at day 10 (7 rats) and 20 (7 rats). After general anestesia full thickness transverse tenotomy with a number 15 blade was made at a point 0.5 cm proximal to distal insertion of the tendons. Achilles tendon was repaired with modified Kessler technique by using 5/0 monofilament polypropylene sutures. All left legs prepared as silicon group (n:21) and all right legs prepared as control group (n:21) thus, comparison of silicon injected tendons and saline injected tendons were achieved on the same rat. In order to optimise silicon effect on the collagen synthesizing fibroblasts, injection was started at day 3, the end of the inflammatory phase. An 0.01 ml sterile monomethyltrisilanol solution (Conjonctyl®, Sedifa Laboratoire, Monaco) was injected peri/intratendinously on the postoperative day 3,5,7,9,11,13,16 and 19 at the each left leg as silicon group. Same dose of sterile saline solution was injected on same days and same manner at the each right leg as control group.Sacrification process was planned at postoperative day 10 (7 rats/14 tendons for biomechanical testing) and 20 (7 rats/14 tendons for biomechanical testing and 7 rats/14 tendons for histologic assessment). For histologic assesment, fibroblast cell count, fibroblast cell diameter, tissue vascularity and diameter of vessels were evaluated with the morphometric analysis at day 20. For biomechanical assesment, tensile strength of the repaired tendons was also measured biomechanically at day 10 and 20. Biomechanical tests were completed in a computer assisted loading device. (LF plus, Lloyds, UK) The Student t test and Mann-Whitney U test were used to evaluate the significance of differences. A difference was considered to be statistically significant when p <0.05 and 0.01. An increased infiltration of active fibroblasts per area was observed with morphometric analysis on tendon repair site of Silicon group at day 20 (Silicon:76,5±25,4; Control:45,5±16,1 p:0,018*) . The fibroblast cell diameter was also statistically high in Silicon group (Silicon:25,3±1,6 A0 ; Control:17,49±1,8 A0 p:0,001*). Vascularization per area (Silicon:39±8,7; Control:27,2±4,9 p:0,011*) and diameter of vessels (Silicon:27,3±3,7 A0; Control:19,4±1,8 A0 p:0,001*) in Silicon group were increased significantly than in control. The collagen fibrils around the active fibroblasts and extracellular matrix in Silicon group exhibited better organisation and stainability. The cross-sectional area of healing tendon in Silicon group was statistically high at day 10 (Silicon: 17±5,8 mm2 ; Control:10,5±4,5 mm2 p:0,039*) and 20 (Silicon: 15,3±2,6 mm2 ; Control:10,4±2,3 mm2 p:0,003*). The healing tendon constructs in the Silicon group had better failure loads than control group at day 10 (Silicon:45,4±5,7 N; Control:34,7±10,8 N p:0,041*). The difference between two groups was not significant at day 20 (Silicon: 44±22,9 N ; Control:35,4±14,7 N p:0,42). The failure site in all samples was in the tendinous portion of the healing tendon. Our results are in agreement with our initial hypothesis, organic silicon enhances the tendon healing in early phase and suitable for further studies on early mobilization after tendon surgery.