published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

In summary, the biomechanical stimulations can augment osteotendinous healing processes by facilitating better fibrocartilagious transitional zone regeneration as well as the restoration of proprioceptions, and the early application showed the more beneficial effects. However, further experimental and clinical studies are still needed to explore the optimal timing, intensity, frequency, and duration of the proposed postoperative biomechanical stimulation protocols. / LIPUS is a "non-contact" biomechanical stimulation, which can provide a direct mechanical stimulation through cavitation and acoustic microstreaming effects to improve tissue healing in a less-than-rigid biomechanical environment. So the mechanical stimulation induced from LIPUS could be applied immediately after surgery without worrying about the mechanical strain exceed the structural property at the osteotendinous healing interface in the early phase of repair. In this part of study, we also examined the effects of the regime of biomechanical stimulations applying immediately after repair on the osteotendinous healing interface. By using the same healing junction model, forty-two female New Zealand white rabbits were randomly divided into two groups; daily mechanical stimulation was applied immediately after surgery lasting up to post-operative 12 weeks on the healing interface in the treatment group. The regime of mechanical stimulations included by LIPUS was 20 minutes, 5 days per week for 4 weeks, followed by cyclic mechanical stimulation generated from quadriceps muscles induced by FES for 8 weeks. Results showed that early application of biomechanical stimulations on the osteotendinous healing interface were significantly better radiologically, histologically and biomechanically than that of not any or later application of the biomechanical stimulations during the osteotendinous healing processes when assessing at the same healing time point. In addition, the early application of biomechanical stimulations showed the better functional recovery in terms of the restoration of the proprioceptions, which an increased numbers of sensory nerve endings labeled by calcitonin gene-relate peptide (CGRP) was detected in the whole osteotendinous healing complex. / Sports or trauma injuries around osteotendinous junctions are common; treatments usually require surgical reattachment of the involved tendon to bone. Restoration of osteotendinous junction after repair is slow and difficult due to regenerating the intermitted fibrocartilage zone to connect two different characteristic tissues, tendon to bone. Although the factors influencing fibrocartilage zone regeneration and remodeling during osteotendinous repair are poorly understood, however, is believed that the mechanical environment plays an important role in such healing process. In present study, the effects of mechanical stimulation on osteotendinous healing process were examined, in the way of mechanical stimulations induced by biophysical stimulations, surface functional electric stimulation (FES) and low intensity pulsed ultrasound (LIPUS), applying on the patellar tendon to patellar bone healing interface in an established partial patellectomy model in rabbits. / The mechanotransductive stimulation linked to the transmission of forces across osteotendinous junction can be generated from its muscle contraction induced by FES. In the partial patellectomy model, thirty-five female New Zealand white rabbits were randomly divided into two groups with initial immobilization for 6 weeks, daily FES was applied to quadriceps muscles for 30 minutes, 5 days per week for 6 weeks in treatment group and compared with non-treatment control group at postoperative week 6, 12 and 18, radiologically, histologically and biomechanically. Results showed that FES-induced cyclic mechanical stimulation significantly increased new bone formation and its bone mineral density. An elevated expression of tenascin C and TGFbeta1; an increased proteoglycant stainability; mature fibrocartilage zone formation with better resumptions of biomechanical properties also observed on the osteotendinous healing interface, indicating that the post-operative programmed cyclic mechanical stimulation generated from its muscle contraction has beneficial effects on osteotendinous healing processes by facilitating the fibrocartilagious transitional zone regeneration. / by Wang Wen. / Advisers: Kai Ming Chan; Ling Qin. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1550. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 159-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Establishment of animal model for studying treatment efficacy of low-intensity pulsed ultrasound stimulations for accelerating bone-tendon repair. Standard partial patellectomy was conducted in the 18-week old rabbits that were then divided into the LIPUS treatment and control groups. The animals were followed for 2, 4, 8, and 16 weeks for various tissue analyses. LIPUS was applied to the experimental animals from postoperative day 3 to 16 weeks. We demonstrated that the healing process of PPT junction was initiated through endochondral ossification. The results showed that the size and length of newly formed bone, and its bone mineral content (BMC), but not its bone mineral density (BMD) were correlated with the failure load, ultimate strength and energy at failure. Using radiographic, biomechanical, histomorphologic and biomechanical methods, it was found that LIPUS had significant accelerating effect on PPT junction repair. We validated our study hypothesis in that LIPUS enhances bone-tendon junction healing by stimulating angiogenesis, chondrogenesis and osteogenesis. / Establishment of in vitro model for mechanism study on effects of low-intensity pulsed ultrasound stimulations. An in vitro model of osteoblast-like cell line (SaOS-2 cells) was studied using cDNA microarray to explore the molecular mechanism mediated by LIPUS. This microarray analysis revealed a total of 165 genes that were regulated at 4 and 24 hours by LIPUS treatment in osteoblastic-like cells. These genes belonged to more than ten protein families based on their function and were involved in some signal transduction pathways. This study has validated the hypothesis that LIPUS can regulate a number of critical genes transient expressions in osteoblast cell line Saos-2. / Keywords. partial patellectomy model; bone-tendon junction repair; low intensity pulsed ultrasound stimulations (LIPUS); gene expression; complementary DNA microarray; rabbit. / This study explored the intact morphology, regular healing and the augmented healing under the effects of low intensity pulsed ultrasound stimulations (LIPUS) on the patella-patella tendon (PPT) junction in a rabbit partial patellectomy model. To probe its possible mechanism, the key genes involved in regulating osteogenesis mediated by LIPUS were identified using the state-of-the-art methods---complementary DNA microarray. / Lu Hongbin. / "June 2006." / Advisers: Ling Qin; Kwok Sui Leung. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1548. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 259-288). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

A direct bone tendon junction consists of four zones: tendon, uncalcified fibrocartilage, calcified fibrocartilage, and bone. The uncalcified and calcified fibrocartilage together forms the transition zone. This organization ensures a gradual transition in stiffness and material properties, and protects the junction from failure. Transition zone regeneration during bone tendon junction healing is important to restore this unique protective mechanism. / Bone tendon junction repair is involved in many orthopaedic reconstructive procedures. Healing is observed to be slow. The junction often heals by fibrous tissue formation. Previous attempts to enhance bone tendon junction healing have resulted in increased bone formation. However, fibrocartilage transition zone is not restored. / This thesis describes a series of studies on transition zone regeneration in bone tendon junction healing using two partial patellectomy animal models. The healing process inside a bone trough was first studied and characterized. Little transition zone regeneration was observed except near the articular cartilage cut surface. The possibility of using articular cartilage to stimulate transition zone regeneration was explored. Both articular cartilage autograft and allogeneic cultured chondrocyte pellet implantations resulted in significantly increased fibrocartilage transition zone regeneration. Cell tracking indicated that the regenerated tissue likely originated from host cells. To elucidate the mechanism of stimulation by allogeneic cultured chondrocyte pellet, the role of cellular and matrix component needed to be differentiated. Freezing and rapid freeze thaw cycles permanently devitalized the allogeneic cultured chondrocyte pellet, but retained its structural integrity and matrix contents. Preliminary results indicated that implantation of the devitalized allogeneic cultured chondrocyte pellet could still increase fibrocartilage transition zone regeneration. Cellular activity seemed not to be essential for the stimulatory effect. / With further research and development, it is envisioned that a cartilage-based stimulation method for fibrocartilage transition zone regeneration in bone tendon junction healing will be developed for clinical application. / Wong Wan Nar, Margaret. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3423. / Thesis (M.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 216-231). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.