Determining if an athlete, who has had Anterior Cruciate Ligament (ACL) surgery, is ready to return to sport is a difficult clinical decision, partially due to the lack of standardized evaluation protocols. Since there is a risk of re-injury post-surgery, medical teams need to be cautious. However, athletes who are perceived to be ready to return to sport do not necessarily do so. Some leave sport altogether while others return to a lower competition level. As psychological thoughts and emotions are relevant to athletes’ injury experiences, a psychological component, such as sport confidence, needs to be thoughtfully considered during the return to sport process. Our objectives were to develop the relationship between drop vertical jump (DVJ) performance and physical attributes in young healthy adults and to then apply this relationship to ACL participants. Another objective was to see if the relationship is improved by including confidence (determined from a survey). It was hypothesized that including confidence will predict the ACL participants’ DVJ performance more precisely. Thirty-five participants were in the control group with thirteen participants in the ACL group. All were recreationally active and all had the following anthropometric and performance measurements recorded: height, weight, calf and thigh girth, knee angle, leg dominance, percent body fat, skeletal muscle mass, anaerobic power, balance, and drop vertical jump height. The ACL group also completed a confidence survey. Regression analyses were performed. The results showed that anaerobic power and relative skeletal muscle mass were significant predictors of DVJ performance; however, DVJ performance could not be predicted precisely. The analysis was also carried out by gender. No significant predictors for male’s DVJ performance were found while the significant predictors for female’s DVJ performance were weight, power and knee extension angle. Once again, DVJ performance could not be precisely predicted. On the other hand, results showed that power could be more precisely predicted by body weight than could DVJ performance. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2009-08-19 16:08:52.13

The purpose of this investigation was to evaluate and compare the efficacy of three functional knee braces in stabilizing anterior cruciate ligament (ACL) deficient knees. The subject sample consisted of eighteen males and females with a unilateral ACL deficiency. / The criterion variables consisted of the ability of each brace in controlling internal rotation and knee extension during active movement and knee extension during a high velocity activity (dynamic task). Total displacement of the knee brace during a running test was also evaluated. / The results of this study demonstrated significant differences between the efficacy of the three braces for control of knee extension during active movement, knee extension during a dynamic task and brace migration during a running task. There was no significant difference between the efficacy of the three braces in controlling internal rotation during active movement.

Det finns idag ingen konsensus om den optimala rehabiliteringen efter en främre korsbandsrekonstruktion, vi vet heller inte idag huruvida rehabiliteringen ska specificeras efter parametrar som kön och ålder. Studien var en korrelerande tvärsnittsstudie med syfte att ta reda på om det förelåg någon skillnad i postoperativ lårmuskelstyrka 4-7 månader efter en korsbandsrekonstruktion med avseende på kön, ålder, skada och typ av operativt ingrepp. Av de 330 aktuella försökspersonerna var det endast 74 personer som godkänt deltagande och uppfyllde kraven för inklusionskriterierna. Försökspersonerna testades i en isokinetisk dynamometer(Biodex) för maximal styrka(60gr/s) och uthållig styrka(180gr/s). Resultaten presenterades genom ett Limb Symmetry Index. Studien fann inga signifikanta skillnader i de undersökta parametrarna mellan försökspersonerna i uppmätt lårmuskelstyrka mellan opererade och icke opererade benet. Detta tyder på att ålder och kön inte är avgörande vid initial rehabilitering avseende post operativ lårmuskelstyrka.

The purpose of this investigation was to objectively evaluate whether three functional de-rotational knee braces stabilize an anterior cruciate ligament (ACL) deficiency. The subject sample consisted of fifteen males and females with a unilateral ACL deficiency. The data for each subject was obtained using the Genucom Knee Analyzer. A right knee-left knee anterior laxity difference of 3mm or greater served as a subject inclusion parameter for protocol completion. The inclusion criteria reduced the subject sample to a total of eleven. / The study consisted of a randomized block design. The experimental design consisted of three parts: (1) an investigation of translational stability, (2) an investigation of rotatory stability, and (3) a comparison between the three braces. / The analysis involved a one way ANOVA of the criterion variables; anterior laxity (ALAX), anterior midrange stiffness (AMRS), anterior endrange stiffness (AERS), internal laxity (ILAX), and translation of the lateral tibial plateau (TLTP). / The AMRS characteristics differed significantly (alpha = 0.05) at 20$ sp circ$ flexion. The results were the following: $-$10.00 $ pm$ 9.78 N/mm for brace 1, $-$2.86 $ pm$ 7.2 N/mm for brace 2 and $-$41.02 $ pm$ 14.79 N/mm for brace 3. The values evaluated for ALAX, AERS, ILAX, and TLTP profiles did not differ significantly between knee braces.

Cervical spine injury can range from minor to severe or fatal, where severe injuries can result in incomplete or complete quadriplegia. There are close to 45,000 Canadians currently affected by paralysis due to traumatic spinal cord injury (tSCI) with an estimated 1700 new cases each year. The majority of tSCI occur in automotive collisions, and current methods for injury prediction are limited to predicting the likelihood for occupant injury but lack the detail to predict the specific injury and location at the tissue level. This research focused on major injuries associated with high impact automotive collisions such as rollover type collisions. Although whiplash is an injury commonly associated with automotive collisions, it was not considered for this study based on the low risk of neurological impairment. The goal of this study was to develop a cervical spine segment finite element model capable of predicting severe injuries such as ligament tears, disc failure, and bone fracture. The segment models used in this study were developed from previous cervical spine segment models representative of a 50th percentile male. The segment models included the vertebrae, detailed representations of the disc annulus fibres and nucleus, and the associated ligaments. The original model was previously verified and validated under quasi-static loading conditions for physiological ranges of motion. To accomplish the objectives of this research, the original models were modified to include updated material properties with the ability to represent tissue damage corresponding to injuries. Additional verification of the model was required to verify that the new material properties provided a physically correct response. Progressive failure was introduced in the ligament elements to produce a more biofidelic failure response and a tied contact between the vertebral bony endplates and the disc was used to represent disc avulsion. To represent the onset of bone fracture, a critical plastic strain failure criterion was implemented, and elements exceeding this criterion were eroded. The changes made to the material models were based on experimental studies and were not calibrated to produce a specific result. After verifying the modifications were implemented successfully, the models were validated against experimental segment failure tests. Modes of loading investigated included tension, compression, flexion, extension and axial rotation. In each case, the simulated response of the segment was evaluated against the average failure load, displacement at failure, and the observed injuries reported in the experimental studies. Additionally, qualitative analysis of elevated stress locations in the model were compared to reported fracture sites. Overall, the simulations showed good agreement with the experimental failure values, and produced tissue failure that was representative of the observed tissue damage in the experimental tests. The results of this research have provided a solid basis for cervical spine segment level injury prediction. Some limitations include the current implementation of bone fracture under compressive loads, and failure within the annulus fibrosus fibres of the disc should be investigated for future models. In addition to material model modifications, further investigation into the kinetics and kinematics of the upper cervical spine segment are important to better understand the complex interactions between the bone geometry and ligaments. This would give insight into the initial positioning and expected response in subsequent models. Future research will include integrating the current segment-level failure criteria into a full cervical spine model for the purpose of predicting severe cervical spine injury in simulated crash scenarios, with future applications in sports injury prevention and protective equipment.

The pressure-tension hypothesis is the governing dogma of orthodontic tooth movement. This theory proposes that the application of loads to the crown of a tooth during orthodontic mechano-therapy results in differential site-specific reactionary strains in the para-dental tissues. Briefly, following the application of orthodontic load the bone and periodontal ligament (PDL) on one side of the tooth is placed in compression favoring bone resorption, while on the other side of the tooth they are placed in tension favoring osteogenesis The present in vitro model provides a surrogate for the PDL on the tension side of the tooth during orthodontic tooth movement and aims to identify mechanically induced changes in the expression of osteo-regulatory cytokines in human PDL cell cultures in response to tensile mechanical strain. Materials and Methods: PDL explants were obtained from pathology free bicuspids of two human subjects following extraction of the teeth for orthodontic purposes. Following serial passage, cells were plated on Uniflex� plates and consigned to either the experimental or control groups. Experimental cells were exposed to a cyclic uniaxial tensile mechanical strain for 6,12 or 24 hours using the Flexercell FX 4000 strain unit. Total RNA was extracted using a two-step procedure and samples were analysed using real-time RT-PCR assays for a range of osteo-regulatory cytokines. Results: Human PDL cells expressed mRNA for a range of cytokines of known significance to osteogenesis and osteoclastogenesis in response to mechanical stimulation. Conclusions: The production of osteo-regulatory cytokines by PDL cells in response to mechanical strain suggests that these cells have the potential to contribute to the osseous modeling of orthodontic tooth movement. The presence of osteogenic signalling drive in response to tensile strain tends to support the basic assertions of the pressure-tension hypothesis.

Thesis (MAppSc in Physiotherapy)--University of South Australia, 1996

Thesis (Ph.D.)--University of Adelaide, Dental School, 2002. / Includes bibliographical references (leaves 355-403).

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.