Browsing by Author "Zernicke, Ronald F."
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Item Open Access A comparison of home vs. physiotherapy-supervised rehabilitation programs following reconstruction of the anterior cruciate ligament (ACL)(2002) Grant, John Andrew; Zernicke, Ronald F.; Montadi, Nick G.Item Open Access Bisphosphonate antiresorptive drug use in a rabbit model of osteoarthritis(2004) Doschak, Michael Roman; Zernicke, Ronald F.Following anterior cruciate ligament rupture (ACLX) in the knee, rapid periarticular bone loss often occurs prior to the subchondral sclerosis of end-stage osteoarthritis (OA). In a model of knee osteoarthritis, changes were examined in subchondral periarticular bone mineral and microarchitecture (IlCT) and in the femoral insertion of the medial collateral ligament (MCL). Also assessed were whether antiresorptive therapy with a bisphosphonate (BP [risedronate]) altered those bone adaptations in the subchondral plate, at the MCL-insertion, and after ACL-reconstruction, and if BP intervention influenced ligament-complex biomechanics and OA progression. Finally, molecular expression of a bone cytokine (osteoprotegerin [OPG]) in periarticular tissues undergoing remodeling and the influence of BP therapy upon the regulation of that gene were investigated. Early alterations of periarticular bone mineral after ACLX included significant loss in subchondral trabecular bone and in bone at the MCL-insertion. Compared to normal controls, MCL-complex laxity and bone loss at the MCL-insertion were significantly greater in the ACLX cohort at 6 wk and had increased further by 14 wk after ACLX. If ACLX animals were dosed daily with risedronate bisphosphonate for 6 wk, however, MCL-complex laxity was significantly improved, and the loss of MCL insertional bone was significantly less and not significantly different from normal control animals. When animals were dosed up to 24 wk after ACLX with BP, however, the progression of OA was not altered. The transient restabilization of the joint by ACL-reconstruction, in conjunction with BP-dosing, did little to block the progression of OA. The expression of OPG was altered following loss of the ACL, and the BP risedronate countered that effect-resulting in the return of OPG expression in bone and fibrocartilaginous tissues. Such adaptive responses in connective tissues after ACLX may have been necessary for the maintenance and repair of the injured structures. The results suggested a potential therapeutic role for antiresorptive bisphosphonate therapy to inhibit adaptive remodeling early following non-fracture joint trauma. Long-term administration of the BP, however, did not appear to be beneficial, and the ultimate effect of the short-term use of the BP on osteoarthritis progression remains to be determined.Item Open Access Bone mechanics in transplanted osteochondral grafts(2002) Wohl, Gregory Robert; Zernicke, Ronald F.Item Open Access Computational analysis of bone fluid flow(2009) Goulet, Grant Carr; Zernicke, Ronald F.; Martinuzzi, RobertItem Open Access Development and validation of an experimental technique for studying dynamic stability during standing(2003) Gildenhuys, Anne; Ronsky, Janet L.; Zernicke, Ronald F.Item Open Access Effects of functional ankle instability on ankle joint complex dynamics and motor control(2006) Monteleone, Bradley John; Zernicke, Ronald F.Item Open Access Effects of low magnitude, high frequency vibrations on bone fracture healing(2008) Fried, Aviv; Zernicke, Ronald F.Item Open Access Effects of varied ankle-foot orthotic resistance on joint mechanics and muscle activation patterns during locomotion(2005) Schneider, Prism Steorra; Zernicke, Ronald F.Item Open Access Estimation of scoliosis severity from the torso surface by neural networks(2001) Jaremko, Jacob Lester; Zernicke, Ronald F.Item Open Access Fluid flow modelling in cortical bone(2005) Hamilton, Nicolas; Zernicke, Ronald F.It is well accepted that loading-induced fluid flow is one of the key factors in triggering bone modeling and remodelling processes through which bones maintain adequate bone mass and architecture. To develop a unique model to provide a more complete picture of fluid flow in bone, STARS, a CMG (Computer Modeling Group Ltd.) porous media fluid flow and mechanical displacement simulator designed for oil recovery applications, was implemented. Three models were constructed to run on STARS to study the effect of cyclical loading and diffusion on fluid flow and nutrient transport in cortical bone. These models included a mouse tibia model, based on a 2D ?CT image, a human bone sample model based on a 3D ?CT reconstruction and an idealized osteon model. The results revealed the sites of high and low fluid flow as well as tracer transport at the full bone and osteon levels.Item Open Access Functional abilities and quality of life of Canadian unilateral transtibial amputees as a function of socket design(2004) Uribarri, Maria Jose Alvarez; Zernicke, Ronald F.Quality of life and functional ability levels in unilateral transtibial amputees were evaluated with the SAQLUTA questionnaire, and were compared between subjects using plaster cast prosthetic sockets and those using CAD/CAM sockets. The sample of 102 individuals had a mean age of 55 ±15 years. Reliability was confirmed with good internal consistency across six subscales, and construct validity was supported with factor analysis. Prosthesis use, satisfaction with the prosthesis, and quality of life were high. Complex locomotor activities posed the greatest challenges. Subjects in the always CAD (AC) group had significantly greater difficulty with mobility and locomotion than subjects in the always plaster (AP) and plaster to CAD (P/C) groups. The challenges reported by women and older individuals appeared to have influenced the performance of the AC socket group. Subjects in the AP group did not report lower levels of functional abilities and quality of life than the AC group.Item Open Access Functional adaptation of bone(2004) LaMothe, Jeremy Michael; Zernicke, Ronald F.Mechanical stimuli can be a vital determinant of bone morphology. How bones perceive and respond to those stimuli remains equivocal, but intracortical bone fluid flow has been suggested to influence bone cell activities. The current studies were designed to determine indirectly relations between intracortical fluid flow and adaptive osteogenesis. A cantilever loading device was constructed to apply non-invasive loads to skeletally mature female C57BL/6 tibiae 5 d·wk-1 for 4 wk. Double calcein injections were administered to permit histomorphometrical indices of adaptation. Loading was conducted while under halothane anaesthesia. Halothane was found to be a good anaesthetic agent for chronic adaptation studies as it did not confound histomorphometrical indices of osteogenesis. Periosteal osteogenesis exhibited a doseresponse relation with loading rate. Those adaptations were histomorphometrically and biomechanically relevant. When loading cycles were separated by brief rest periods (< 1 s), osteogenesis was significantly enhanced. Similarly, longer rest periods (10 s) were effectively used in combination with short bouts of high-frequency loading regimes. The current studies also showed substantial periosteal responses and slight endosteal responses. Periosteal osteogenesis was significantly negatively correlated with endosteal osteogenesis; the spatial distribution of osteogenesis showed that medial-lateral tibial cantilever bending accelerated an age-related modeling drift. Spatially, endosteal osteogenesis was significantly correlated with circumferential strain gradients in only two of the loading groups. Thus, no single mechanical parameter could explain adaptive osteogenesis in all of the loading groups supporting the complexity of bone adaptation. The data from the current studies emphasized the sensitivity of the adult skeleton to specific physical parameters. Those parameters the skeleton was most sensitive to related to enhanced intracortical fluid flow velocities and volumes. Optimization of osteogenesis in response to mechanical loading may underpin the development of nonpharmacological regiments designed to increase bone mass.Item Open Access Functional adaptation of bone: interactive effects of diet and mechanical loading environment(2009) Lorincz, Caeley Rae; Zernicke, Ronald F.; Reimer, RayleneNutritional status and physical loading remain two of the most influential modifiable risk factors in the development of osteopenia and osteoporosis. Creating optimal dietary and mechanical loading environments during the susceptible period surrounding development should encourage establishment of peak bone mass and may attenuate bone-related fragility fractures later in life. These studies were designed to investigate the interrelations between a diet previously denoted as deleterious for skeletal integrity (i.e., high saturated fat and sucrose (HFS)) and exogenous loading regimes previously deemed osteogenic. A cantilever loading device was used to apply noninvasive loads 5d/wk for 3wk to the tibiae of skeletally immature female C57BL/6 mice consuming either low-fat complex carbohydrate (LFCC) or HFS diets. Upon completion of the intervention, half the tibiae from each diet cohort were scanned using microcomputed tomography and tested for structural integrity by three-point bending. Expression of RANKL, OPG, COX-2, PPAR-y, and Cathepsin-K mRNA were measured in the other half of tibiae. Serum markers of bone formation ( osteocalcin) and markers of bone resorption (i.e., tartrate resistant acid phosphatase) were measured in cardiac blood. Mice fed an HFS diet were significantly heavier and fatter than LFCC mice. After normalizing for differences in body mass, HFS mice had compromised tibial structural and geometrical parameters, as well as elevated serum markers of bone resorption. RANKL mRNA was significantly elevated, and COX-2 mRNA tended to be elevated in this cohort, suggesting bone loss associated with the chronic inflammatory state of dietinduced obesity. High-magnitude, low-frequency loading did not benefit mice fed a LFCC diet, but did improve structural and geometrical properties in mice fed the HFS diet. When brief rest-periods ( ?? 1 s) were interspersed with the high-frequency loading regime (30 Hz), however, both groups showed positive skeletal adaptation. Adaptation observed in the LFCC cohort was primarily structural, while changes in the HFS cohort were principally geometrical. The reasons for this difference have yet to be elucidated. These data emphasize the complex interrelations between diet and external loading environments on bone health during periods of growth, and highlight the potential for osteogenic loading regimes for individuals with varied nutritional status.Item Open Access Gait changes following total hip replacement(1997) Ajemian, Stanley V.; Zernicke, Ronald F.Item Open Access Leptin Deficiency and Its Effects on Tibial and Vertebral Bone Mechanical Properties in Mature Genetically Lean and Obese JCR:LA-Corpulent Rats(2012-07-19) Reimer, Raylene A.; LaMothe, Jeremy M.; Zernicke, Ronald F.Leptin signaling deficient rodents have emerged as models of obesity/insulin resistance syndrome. Altered leptin signaling, however, can affect axial and appendicular bone geometrical properties differently, and, thus, we hypothesized that leptin-deficiency would differentially influence mechanical properties of vertebrae and tibiae compared to lean rats. Mature (9 mo) leptin receptor deficient obese (cp/cp; n=8) and lean (+/?; n=7) male JCR:LA-corpulent rats were used to test that hypothesis. Tibiae and the sixth lumbar vertebrae (L6) were scanned with micro-CT and were broken in three point-bending (tibiae) or axial loading (L6). Supporting the hypothesis, vertebrae and tibiae were differentially affected by leptin signaling deficiency. Tibiae, but not vertebrae, were significantly shorter in obese rats and achieved a significantly greater load (>18%), displacement (>15%), and stress (>18%) at the proportional limit, relative to the lean rats. Conversely, L6 in obese rats had significantly reduced displacement (>25%) and strain (>32%) at proportional limit, relative to the lean rats. Those combined results suggest that the etiology and duration of obesity may be important determinants of bone mechanical properties, and axial and appendicular bones may be affected differently.Item Open Access Leptin Deficiency and Its Effects on Tibial and Vertebral Bone Mechanical Properties in Mature Genetically Lean and Obese JCR:LA-Corpulent Rats(Hindawi Publishing Corporation, 2012-06-18) De Bruyn (Reimer), Raylene A.; LaMothe, Jeremy M.; Zernicke, Ronald F.Item Open Access Lower extremity biomechanics of children with clubfoot(1999) Davies, Theresa Claire; Zernicke, Ronald F.Item Open Access Measurement of blood flow in bone by laser doppler imaging(2000) Shymkiw, Roxane Chia-Chi; Zernicke, Ronald F.Item Open Access Microstructural bone adaptation in an experimental model of osteoarthritis(2001) Boyd, Steven Kyle; Zernicke, Ronald F.Item Open Access Microstructural bone adaptation in an experimental model of osteoarthrits(2001) Boyd, Steven Kyle; Zernicke, Ronald F.