After knee surgery, the development of leg strength and size to its original levels are important requirements in the recovery. The major aim in the rehabilitation of a meniscectomy is to return the injured limb to its original size by a program of active exercises. Failure to do this may result in limited activity and re-injury to the knee joint A program of electrical stimulation has been found to be effective in controlling muscle atrophy during the time of denervation in animals and humans (in animals - Schimrizk et a 1976; Herbison et al, 1973, 1971; Stillwell et al, 1962 and Guttman and Guttman, 1942; in humans - Osbourne, 1951 and Jackson and Seddon, 1945). At the present time no studies have been done to determine if electrical stimulation will be effective in controlling muscle atrophy in normally innervated muscles during the period of immobilization. The purpose of this investigation was to determine the effects of a 10-12 day program of electrical stimulation on the control of muscle atrophy and strength loss during the period of immobilization. A subproblem of this investigation was to determine the relationship between muscle atrophy and strength loss. The subjects for this study were eighteen patients undergoing a meniscectomy operation (mean age 22.7 yrs.). Subjects were rated according to strength per body weight and assigned to a control or an experimental group. The experimental group participated in a five session program of electrical stimulation in addition to a standard physiotherapy program. The control group participated only in the standard physiotherapy program. The electrical stimulation consisted of five sessions each lasting ten minutes. Ninety muscle contractions were made during the ten minute session. The sessions were held on weekdays within a 10-12 day period of the operation. The first session was held 48 hours after the operation. In the first two sessions the leg was stimulated at the immobilized angle and in the remaining three sessions the leg was stimulated at 115 degrees of extention. All subjects were tested one day prior to the operation and at the end of the 10-12 day period for thigh volume and maximal isometric leg strength. The following hypotheses were tested for significance at the .05 level. 1. The use of electrical stimulation in addition to the standard physiotherapy program will show less muscle atrophy as compared to the standard physiotherapy program. 2. The use of electrical stimulation in addition to the standard physiotherapy program will maintain a higher level of original isometric strength as compared to the standard physiotherapy program. 3. There is a positive linear relationship between muscle atrophy and strength loss. Analysis of variance revealed that hypothesis #1 is supported at the .01 level and hypothesis #2 is not supported at the .05 level of significance. The Pearson Product Moment Correlation showed that hypothesis #3 is supported when the two groups were combined and for the control group only at the .01 level of significance, but not for the treatment group only, at the .05 level. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

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Lors de la cicatrisation, plusieurs types cellulaires dont les kératinocytes et les fibroblastes ainsi que plusieurs facteurs de croissance jouent d’importants rôles. La cicatrisation cutanée peut aussi être activée par des facteurs exogènes, dont la stimulation électrique (SE). La SE peut moduler les fonctions fibroblastiques durant la cicatrisation. Le fibroblaste contribue de façon active à la cicatrisation en sécrétant différentes protéines (collagène, fibronectine, élastine) pour favoriser le comblement tissulaire. Les fibroblastes adoptent aussi un phénotype contractile en exprimant l’α-actine contribuant à la fermeture de la plaie. Notre hypothèse est que certaines de ces fonctions fibroblastiques pourraient être modulées par une stimulation électrique. Pour vérifier cette hypothèse nous avons utilisé une membrane biocompatible et conductrice à base de polyethylene terephthalate (PET) recouvert de polypyrrole (PPy). Les fibroblastes dermiques humains ont été cultivés sur ces membranes conducteurs, puis exposés ou non à un courant pulsé (PES) selon deux régimes : soit 10s PES suivi de 1200s de repos, ou 300s PES suivi de 600s de repos, durant 24 h. Deux intensités électriques ont été étudiées, 50 et 100 mV/mm. Nos travaux démontrent que la SE favorise l’adhésion, la prolifération et la migration des fibroblastes dermiques. Ces activités cellulaires sont consolidées par une sécrétion importante de FGF2 et d’α-SMA. Il est important de noter que l’effet de la SE favorise le changement phénotypique des fibroblastes en myo-fibroblastes grâce à la voie des Smad et de TGFβ/ERK. Nous avons aussi démontré que l’effet de la SE est maintenue à long terme et est transférable de la cellule mère vers les cellules filles. En effet après sous-culture les cellules expriment toujours de façon importante l’α-SMA. En conclusion, nous avons démontré que la stimulation électrique pulsée module positivement les fonctions cicatricielles des fibroblastes humains. Ces travaux démontrent pour la première fois les voies de signalisation (Smad et TGFβ/ERK) sollicitées par la SE pour activer les fibroblastes lors de la cicatrisation. Ces travaux suggèrent l’utilisation de la SE pour favoriser la guérison/cicatrisation des plaies. / During skin wound healing, cutaneous cells particularly fibroblasts and keratinocytes as well as several growth factors play important roles. Wound healing can be activated by exogenous factors, including electrical stimulation (ES). ES can also modulate fibroblast functions. Fibroblasts contribute to healing by secreting structural proteins (collagen, fibronectin, elastin) to repair the wound area. Fibroblasts also adopt a contractile phenotype expressing α-actin contributing to wound closure. The hypothesis of the thesis is that fibroblasts proliferate and transdifferentiate into myofibroblasts by sensing pulsed electrical signals and adjusting relevant signalling pathways. To test this hypothesis we used biocompatible polyethylene terephthalate (PET) fabrics coated with electrically conductive polypyrrole (PPy). Human dermal fibroblasts were cultured on these conductive fabrics and exposed to the optimized pulsed ES: either 10s PES in a period of 1200s, or 300s PES in 600s period, for a total of 24 hours. Two electric intensities were studied, 50 and 100 mV/ mm. Our work showed that the PES promoted the adhesion, proliferation and migration of dermal fibroblasts. These cellular activities were consolidated by an elevated level of fibroblast growth factor 2 (FGF2) and the high expression of α-smooth muscle actin (α-SMA). Important findings were that PES promoted the phenotypic change of fibroblasts to myofibroblasts, and such change was coordinated through the Smad and TGFβ/ERK pathways. It also demonstrated that the effect of PES was able to maintain for a long period of time after the end of stimulation, and was transferable from the mother cells to the daughter cells. Following subculture, the electrically stimulated fibroblasts still expressed significant amount of α-SMA. In conclusion, this thesis demonstrates that PES through conductive fabrics can activate the wound healing functions in human dermal fibroblasts. This work revealed for the first time that Smad and TGFβ/ERK pathways are required by the PES-induced fibroblasts-to-myofibroblasts differentiation. This work also demonstrated that the PES activated cells can survive in vivo. These studies suggest the application of the PES in promoting tissue regeneration and wound healing.