This is an interdisciplinary research project in which the methods of biomechanical and design engineering are focused upon a problem in orthopaedics. The anterior cruciate ligament (ACL) is the major ligament in the knee and is often torn during athletic competition as well as every day activity. The ACL is made up of two functional bundles, which help to stabilize the knee. Until recently, ACL reconstruction only replaced one of these bundles; however, research shows that both bundles should be replaced to more fully restore normal knee functionality. The aim of the research was, therefore, to evaluate the mechanical aspects of the double-tunnel-double-bundle ACL reconstruction technique. The research was directed towards designing a new and improved surgical device to improve ACL reconstruction: The current study used a computational model and experimental testing to explore the mechanical parameters of the tendon graft and knee bones to investigate the effects of double tunnel drilling in tibia and femur during ACL reconstruction. The thesis presents the findings of research into three aspects of double-tunnel-double-bundle ACL reconstruction. The first aspect of the study involves clinical and computational analysis of a single-tunnel-singlebundle (SB) ACL reconstructed knee with a double-tunnel-double-bundle (DB) ACL reconstructed example. The study tried to show the advantage of the DB technique over the conventional SB technique. The anatomical geometries of both SB and DB examples were used to create a finite element model and investigate the relative merits of single and double tunnelling, the variations of graft pretension, and tunnel placement on bone stress. The experimental and computational results of both methods were compared and discussed. The second study investigated whether tripling a tendon when using suspensory fixation provides inferior graft strength and a greater cyclical elongation than a doubled tendon graft with suspensory fixation. The tensile stress was found to be lower in the third strand than in the doubled portion. The study was focussed on the mechanical assessment of two different methods of tripling tendons when using suspensory fixation. The third aspect of the study focussed on the design of a new device for fixation of the femoral tripled tendon graft in DB ACL reconstruction technique. The study describes a series of designs and prototypes that were iteratively developed and experimentally tested, leading to a novel tripled tendon graft device. The function of the new device was compared with the conventional methods and tested with a number of animal tendons and bones. The new device with a tripled tendon graft resulted in higher pull-out strength and less graft elongation than that seen using a conventional tripling method.

Stambiųjų sąnarių endoprotezavimas – viena sėkmingiausių operacijų ortopedijoje, sumažinanti pažeisto sąnario skausmus, atstatanti jo funkciją bei ekonomiškai efektyvi. Tačiau vien tik operacinis gydymas neužtikrina gerų rezultatų, tinkama pooperacinė reabilitacija padeda grąžinti ligoniui savarankiškumą. Skausmas ir nerimas stipriai veikia pooperacinį judėjimo funkcijų atsikūrimą bei pacientų fizinę ir psichinę gerovę, todėl svarbu sudaryti veiksmingą kineziterapijos programą, kuri sumažintų neigiamą šių veiksnių įtaką reabilitacijos kokybei. Krioterapija – efektyvus, tačiau mažai mokslininkų tirtas būdas skausmui po šios operacijos malšinti. Atsipalaidavimo pratimai – būdas sumažinti fizinę bei psichologinę įtampą, norint įveikti nerimą ir depresiją. Tyrimo tikslas. Nustatyti krioterapijos ir atsipalaidavimo pratimų poveikį pacientų skausmui, nerimui bei judėjimo funkcijai po kelio sąnario pakeitimo operacijų. Uždaviniai. 1. Įvertinti kineziterapijos poveikį pacientų skausmui, nerimui bei judėjimo funkcijai po kelio sąnario pakeitimo operacijų. 2. Įvertinti kineziterapijos, derinamos su krioterapija bei atsipalaidavimo pratimais, poveikį pacientų skausmui, nerimui bei judėjimo funkcijai po kelio sąnario pakeitimo operacijų. 3. Palyginti skirtingų kineziterapijos programų efektyvumą. Tyrimo hipotezė. Manome, kad kineziterapija derinama su krioterapija bei atsipalaidavimo pratimais yra efektyvesnė nei tradicinė kineziterapija atgaunant judėjimo funkcijas pacientams... [toliau žr. visą tekstą] / Endoprothesis replacement of a major joint is one of the most successful orthopaedic operations which relieves the pain of the affected joint, repairs its functions, and is economically effective. However, the surgical operation alone does not guarantee good results. An appropriate post-surgical rehabilitation helps return self-dependence to the patient. Pain and anxiety markedly affect the post-surgical recovery of motor functions as well as the patient’s physical and psychical well-being. Therefore, it is important to draw up an effective physical therapy programme which would reduce the influence of these factors on the rehabilitation quality. Cryotherapy is an effective, however, little examined by scientists’ way to relieve the pain after such surgical operations. Relaxation exercises are a way to lessen physical and psychological tension in order to overcome anxiety and depression. Research objective: To ascertain the influence of cryoptherapy and relaxation exercises on patients’ pain, anxiety and motor function after the endoprosthesis replacement of a knee joint. Tasks: 1. To evaluate the influence of physical therapy on patients’ pain, anxiety and motor function after the replacement of a knee joint. 2. To evaluate the influence of physical therapy combined with cryotherapy and relaxation exercises on patients’ pain, anxiety and motor function after the replacement of a knee joint. 3. To compare the effectiveness of different physical therapy programmes. Research... [to full text]

This thesis examined the immediate biomechanical effects of valgus unloader brace application in participants with moderate medial compartment knee osteoarthritis during gait. Thirty-three individuals were prescribed a valgus unloader brace. 3D knee moments and angles were calculated during walking with and without the brace. Principal Component Analysis identified amplitude and temporal changes of the moment and angle waveforms during gait. Three groups were identified based on the change in knee adduction moment magnitude with brace application. Two-Way ANOVA tested for differences among groups and conditions in principal component scores, as well as discrete varus thrust values. There existed three subgroups of participants identified by different gait adaptations to brace application. The brace had temporal and magnitude effects on 3D kinetics and kinematics for the participant group. This study showed that the brace does not provide a consistent change to knee joint mechanics. These results have implications for brace prescription.

Objectives: To investigate differences between hip abductor muscle strength, hip and knee adduction moments and knee joint alignment in people with moderate/severe and mild medial compartment knee osteoarthritis (OA), and people without OA, and identify variables explaining variance in knee adduction moment in participants with OA. Background: It has been suggested that weakness of hip abductor muscles may lead to displacement of the centre of mass of body away from the stance limb during gait, resulting in increased knee adduction moment, a predictor of disease progression. Methods: Participants with medial compartment knee OA were divided into moderate/severe (n=23) and mild OA groups (n=15) based on radiographic grading. Control subjects were recruited to match participants in the moderate/severe group for age and gender (n=23). Hip abductor and adductor muscle isometric strength was measured using the Biodex dynamometer. Gait speed and hip and knee peak adduction moments and percentage of the stance phase where these occurred were obtained using a three dimensional motion analysis system and two force platforms. Knee alignment and severity of OA were measured from radiographs. Statistics: Univariate analysis of variance (ANOVA) was performed to determine group differences. Stepwise linear regression analysis was performed to identify the variables which contribute to variation in knee adduction moment. Results: Moderate/severe OA group participants had higher body mass index (BMI) than the mild OA and control group (p=0.01) and greater varus alignment compared to the control group (p<0.01). There was no difference between the mean hip abductor and adductor muscle strength and hip and knee adduction moments among the three groups. Peak hip (p=0.02) and knee adduction moments (p<0.05) occurred later in stance phase of gait in the moderate/severe OA group as compared to control group. Knee joint alignment (26%), hip abductor muscle isometric strength (20%), gait speed (16%) and hip adduction moment (11%) explained 73% of variance in the knee adduction moment in the participants with OA. Conclusion: Findings from this study do not support the theory that weakness of the hip abductor muscles contributes to higher knee adduction moments. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2008-03-03 21:47:07.309

Background and Purpose: Self-efficacy plays a major role in determining physical function during the earlier stages of the knee osteoarthritis (OA) and it may be a significant factor in the maintenance of physical function across the span of OA severity. This study examined the contribution of self-efficacy to objective and subjective measures of physical function at both maximal and sub-maximal levels. The relationship between self-efficacy and quality of life was also examined. Participants: Twenty community-dwelling adults with knee OA (age 69±14 years) were recruited for this study. Methods: Subjective maximal and sub-maximal performance were determined using the Maximal Activity Score (MAS) and Adjusted Activity Score (AAS) respectively of the Human Activity Profile. The objective measure of sub-maximal physical function was the 6-minute walk test (6MWT) while the Incremental Shuttle Walk Test (ISWT) was the maximal measure. Quality of life was determined using the Short Form Health Survey 36 (SF-36) and self-efficacy was measured using the Arthritis Self-Efficacy (ASE) scale. Disease severity was determined using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). A stepwise multiple linear regression analysis was performed using each of 6MWT, ISWT, AAS and MAS as the dependent variable, and the WOMAC and ASE as independent variables. Results: Self-efficacy explained 44% of the variance in the 6MWT but only 16% in the ISWT. Self-efficacy explained approximately 30% of the variance in both the MAS and AAS. A moderate relationship was observed between self-efficacy and the Physical Component Score (PCS) (r=0.51) of health-related quality of life, but no relationship was observed with the Mental Component Score (MCS). Discussion and Conclusion: In mild to moderate knee OA, sub-maximal physical function was substantively influenced by an individual’s belief in his/her ability to perform a given task, but not so when the intensity of the activity approached maximal levels. This differential relationship between sub-maximal and maximal performance was not present using subjective reports of performance. These findings indicate that therapy utilizing training at sub-maximal levels in mild to moderate knee OA should focus on strategies for enhancing self-efficacy; whereas with training at relatively high intensities, less focus should be given to enhancing self-efficacy. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2008-04-25 15:28:10.666

The purpose of this investigation was to document the influence of the anterior cruciate ligament (ACL) in controlling the dynamic interaction between the femur and tibia. Twenty subjects were initially selected to participate based on the results of arthroscopic and proprioceptive tests which established the presence of a uni-lateral, third degree rupture of the ACL. A spline function established the best fitting curve of the instant center (IC) coordinates obtained throughout the ROM. Displacement variables were extrapolated from joint rotation profiles generated from these coordinates. Abnormal displacement migrations of the IC parameter were demonstrated to occur in extension. Migration displacements evaluated between 30$ sp circ$ and 0$ sp circ$ shifted anteriorly 5.07 $ pm$ 1.86 mm for intact knees and 6.97 $ pm$ 2.06 mm for involved knees. This was determined to be significant at the 0.05 level of confidence and correlated well with clinical findings. Mean migration displacements evaluated in flexion (between 100$ sp circ$ and 70$ sp circ)$ were not found to differ significantly between knee conditions.

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Movement variability that occurs while performing repetitions of any particular motion can be due to errors in one’s ability to select the required parameters for executing the movement. However, it has been suggested that an optimal amount of variability exists in a healthy system providing adaptability to varying situations while producing negligible errors. Investigation of the consistency of movement variability in a system may provide information regarding joint control and integrity since the functionality of a system can be disrupted by injury. Rupture of the anterior cruciate ligament is associated with deficits in knee joint stability and mobility, as well as altered movement patterns. There is value in developing a simple clinical test that can measure knee joint stability and evaluate the degree of knee damage and rate of progress during rehabilitation. The main objectives were to investigate the normal range of variability during repeated knee extensions in healthy subjects and subjects with a reconstructed anterior cruciate ligament, and to evaluate the reliability of the method. There were 30 participants in the control group and 8 in the subject group. All were physically active a minimum of 2-3 times per week for a total of 2-3 hours. Mean variance and mean correlation were used to evaluate variability in this study. Change in mean variance and mean correlation, standard error of measurement and intra-class correlation coefficient were used to evaluate reliability. The results showed the range of values for movement variability in control and subject groups. Standard error of measurement indicated mean correlation (1.31% to 2.38%) was more reliable than mean variance (21.80% to 54.87%). Mean variance and mean correlation significantly increased with speed, and mean correlation was significantly higher for dominant legs during trials at 70 beats per minute. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2014-06-02 12:18:42.802

No description available.

The tribology of a wide range of designs of compliant layer acetabular cups has been evaluated using a simulator. The simulator applied a dynamic load of 2 kN and a sinusoidal motion of ±25 , and measured the frictional resistance directly. In general the friction developed in these joints was extremely low, with friction factors typically below 0.01. When the experimental results were compared with theoretical estimates of friction a poor correlation was found. Further analysis suggested that the design of compliant layer acetabular cups was insensitive to many of the parameters suggested by theory. In particular, the radial clearance and femoral head size were not found to be critical. In addition, methods were proposed and their effectiveness demonstrated to measure friction at the on-set of motion (start-up friction), and the steady state friction in realistic compliant layer knees. The adhesion between compliant layers and a rigid backing have been investigated, with the aim of developing a good bond between them. The peel test was used to demonstrate an excellent diffusion bond between a low modulus medical grade polyurethane, and a similar high modulus grade of polyurethane. The processing conditions used to manufacture the test piece were optimised to maximise the bond strength. The bond was found to be stable after immersion in Ringers solution at 37 C for 52 weeks, and after acetabular cups were subjected to 14 million 4 kN loading cycles. A six station knee wear simulator was designed and commissioned. The simulator applied a dynamic load and an anterior-posterior translation individually to each station, as well as a flexion-extension motion common to all six stations. The simulator was computer controlled entirely using servo hydraulics. Wear rates were obtained from tests lasting up to 8 million cycles conducted on UHMWPE joints.