Author: Chan, Oi Wan Karly
Title: Effect of fish oil application and its combined effect with therapeutic ultrasound on tendon healing : a rat model
Advisors: Ng, Gabriel (RS)
Degree: Ph.D.
Year: 2018
Subject: Hong Kong Polytechnic University -- Dissertations
Achilles tendon -- Wounds and injuries -- Treatment
Tendons -- Diseases -- Animal models
Department: Department of Rehabilitation Sciences
Pages: xxii, 172 pages : color illustrations
Language: English
Abstract: Full recovery of acute Achilles tendon rupture may not complete even at 2 years after injury irrespective of the type of treatment. This could be due to the deficiencies of current treatments, thus the need of exploring safe and effective long term treatment is implicated. Fish oil which contains high proportions of omega-3 polyunsaturated fatty acids (n-3 PUFAs) particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has been shown to modulate inflammation, promote connective tissue healing, collagen synthesis and cutaneous wound healing in animal model. The lipophilicity and relative small molecular weight of n-3 PUFAs make them potential agents to penetrate the skin and hence serve as skin drug permeation enhancer. Therapeutic ultrasound has been used to treat soft tissue injuries for over half a century. It can also serve as transdermal enhancement modality. In light of this, the present series of studies were conducted to examine the biomechanical properties, histomorphological changes and collagen deposition of rupture tendons after 2-week and 4-week treatment of topical fish oil, therapeutic ultrasound and the combination of the two modalities. A total of 121 female Sprague-Dawley rats were tested. All the rats underwent the same surgical procedures that the right Achilles tendon was partially transected. The animals were randomly assigned into 4 groups, namely, control (CON), topical fish oil (FO), therapeutic ultrasound (US) and therapeutic ultrasound coupling with topical fish oil (FU). The animals received daily treatment at one day after surgery according to their group assignment for a period of either 2 weeks or 4 weeks. After the treatment period, all the rats were sacrificed and their Achilles tendons were harvested for analysis of biomechanical performance, histomorphological changes and collagen deposition. Results were analyzed using two-way analysis of variance (ANOVA).
The biomechanical analysis involved 85 rats and their Achilles tendons were tested for structural stiffness, ultimate tensile strength (UTS) and energy absorption capacity. At 2 weeks, only US group showed higher normalized UTS when compared with CON group (p<0.05). At 4 weeks, both US and FU groups demonstrated better UTS (p< 0.05), while both FO and FU groups had improved in structural stiffness (p<0.05). Four weeks of treatment with ultrasound using fish oil as coupling medium showed improvement in both structural stiffness and UTS (p<0.05). The histomorphological and collagen analysis involved 36 rats. A histological examination was performed using hematoxylin and eosin, Masson's trichrome and Picrosirius red stain. Immunohistological examination was used to distinguish type I and III collagen and to quantify immuno-positive-stained areas. Histological analysis suggested that FU group had more mature collagen fibre (p<0.05) at 4 weeks. The US group demonstrated significantly higher percentages of type I and type III collagen at 2 weeks (p<0.05). There were higher percentages of type I collagen at 2 weeks (P<0.05) and a higher proportion of mature collagen at 4 weeks in FO group (p<0.05). These findings demonstrated that therapeutic ultrasound expedited the healing response particularly in the early phase of healing while fish oil treatment had a more sustained effect on collagen deposition. From the series of studies, it is concluded that therapeutic ultrasound coupled with topical fish oil could better restore UTS, stiffness, extracellular matrix organization and enhance mature collagen deposition.
Rights: All rights reserved
Access: open access

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