Flexor tendon healing: evaluation of peritendinous adhesion formation and tendon strength after tenotomy and primary repair in an ovine model

Abstract

This experimental study was designed to assess the effects of different surgical repair techniques on the process of flexor tendon healing. In particular it aimed to evaluate the effects of incorporating a novel biocompatible, biodegradable 'wrap' into the process of tendon repair. This inorganic polymer wrap, Controlled Release Glass, (Giltech Limited, Ayr, Scotland, UK) was composed of a combination of sodium and calcium cations with phosphate and oxide anions and degraded into simple ionic substances normally found in tissue fluid. The hypothesis to be tested stated that 'the addition of this potentially anti-adhesiogenic substance to the process of flexor tendon repair would result in no difference in musculoskeletal function or tendon characteristics after recovery'.Tenotomy and primary repair of the ovine Flexor Digitorum Superficialis Pars Superficialis slip was performed using a variety of different repair methods, involving combinations of the following elements of repair; modified Kessler core suture, circumferential epitenon suture, CRG wrap, triamcinolone paste. Eleven experimental groups of twelve cases each were set-up and evaluated in two time cohorts; six weeks and six months after surgery. A control group of twelve nonoperated cases was also assessed.Outcome was measured using a combination of standard in vitro tests (tensile strength, morphometry and percent composition) and in addition two in vivo assessments (Laser Doppler Blood Flowmetry and dynamic testing of displacement, velocity and acceleration).Results of statistical analyses showed that for the experimental groups containing CRG wrap, the proliferative vascular response to injury was diminished toward 'normal' range at six weeks, and within 'normal' range by six months after repair. This occurred in the absence of any significant difference in superficial blood flow beyond the site ofrepair or in the strength ofthese groups ofrepaired tendons.Also, at six weeks after operation these experimental groups showed a reduction in fibrous tissue at the sites of tendon repair without any other significant differences in morphological features of the healing tendons. The implications for clinical practice of these findings are discussed.