As the number of total knee arthroplasty (TKA) procedures increases annually, the patient demographic is shifting to include younger patients with higher expectations for post-operative function. The aim of this study was to compare movement patterns during activities of daily living among TKA patients and a healthy, age-matched group using 3D motion analysis. Specifically, this analysis looked at walking on level and inclined surfaces, as well as sitting up and down from a chair. It was predicted that (1) TKA patients would exhibit reduced knee extension moments at the operated limb and increased adduction moments at the contralateral limb during gait, (2) walking downhill would result in greater differences between TKA and control groups, compared to level walking, and (3) TKA participants would have greater flexion angles, moments and power values at the hip, compared to controls, during the sit-stand tasks. Seventeen participants (age=62±6 years, BMI=30±3 kg/m2, time after surgery=11±5 months) were recruited from the Ottawa Hospital, having undergone unilateral TKA by the same surgeon. An age-matched control group was composed of 17 individuals (age=63±8 years, BMI=27±4 kg/m2) who were recruited from the local community. Three dimensional (3D) biomechanical assessment was conducted with all participants performing five trials of walking on level and inclined surfaces, stair ascent and descent as well as sit-stand tasks. Results from this study were focused on gait and sit-stand transitions, showing that TKA participants exhibited altered gait patterns on both walking surfaces, with significantly smaller knee flexion angles and moments, as well as reduced peak power at the knee. The TKA group also experienced reduced knee extension moments; however, this was only significant for downhill walking. Consistent with our hypothesis, downhill walking resulted in greater discrepancies between the groups compared to level walking. Contrary to our third hypothesis, TKA participants exhibited significantly smaller peak hip flexion angles and moments during the sit-stand task, along with reduced hip abduction angles and knee abduction moments. The reduced knee flexion kinematics and kinetics observed during gait tasks, combined with the differences in frontal plane mechanics observed during the sit-stand task suggest that altered loading patterns persist six to twelve months after surgery. This may be a result of continued pre-operative movement patterns as well as the surgery itself, and should be kept in mind when developing rehabilitation programs for this patient population.

Pitting and delamination wear of ultra high molecular weight polyethylene (UHMW-PE) tibial plateaux for total joint replacements have habitually been attributed to a fatigue crack growth mechanism associated with a combination of high sub-surface cyclic shear stresses and degradation of the chemistry and structure of UHMW-PE caused by the gamma-irradiation sterilisation standard procedure. However, the exact mechanisms by which cracks initiate and grow in UHMWPE are not known and the relationships between these mechanisms and pitting and delamination are only assumptions based on qualitative observations. A fracture mechanics approach based on the J-integral concept of plane strain crack initiation toughness was therefore applied in order to firstly obtain the fracture toughness and crack growth stability of UHMW-PE and secondly to determine the mechanisms by which pitting and delamination occur in vivo. It was necessary to modify the existing standard ASTM E813-89 for the treatment of experimental J data in order to accommodate for the large crack tip plasticity and pronounced ductile tearing. This modified method was then applied to a detailed investigation of the influence of sterilisation and ageing on the chemical, physical and mechanical properties of UHMW-PE. Simulated shelf and in vivo environments enabling a rapid ageing of UHMW-PE corresponding to 10 years of natural ageing were developed. Sterilisation was either conducted by gamma-irradiation in air or nitrogen, or by gas plasma. In virgin UHMW-PE, cracks propagated by a succession of plastic deformation and craze nucleation over thin layers of material, yielding a very high value of J (90 kJ/m 2 ) at 37 : C. Gammairradiation in air followed by 10 years ageing resulted in a highly brittle material with a crack initiation fracture toughness reduced by 78% and a mechanical behaviour approaching that of a linear elastic material i.e. creation of a "cup-and-cone" in tension and formation of 45" shear lips in threepoint bending. On the other hand, gas plasma sterilised UHMW-PE could not be differentiated from unsterile UHMW-PE in either its physical nor mechanical properties. Qualitative correlations existed between the presence and location of highly oxidised regions and the crack initiation fracture toughness of the material. Quantitatively, the J-initiation toughness exhibited a hyperbolic decrease with increasing density and oxidation index while the tensile secant modulus linearly increased with density. From these empirical relationships, a model was created which described the variation of the fracture toughness with depth within a UHMW-PE sample. This model indicated that the zones of high density, oxidation and crystallinity correspond to the areas of maximum shear stress and minimum fracture toughness and that the propensity of UHMW-PE to suffer pitting, delamination and high wear rates through a fracture mechanism is significantly increased by extensive oxidative degradation.

As the number of total knee arthroplasty (TKA) procedures increases annually, the patient demographic is shifting to include younger patients with higher expectations for post-operative function. The aim of this study was to compare movement patterns during activities of daily living among TKA patients and a healthy, age-matched group using 3D motion analysis. Specifically, this analysis looked at walking on level and inclined surfaces, as well as sitting up and down from a chair. It was predicted that (1) TKA patients would exhibit reduced knee extension moments at the operated limb and increased adduction moments at the contralateral limb during gait, (2) walking downhill would result in greater differences between TKA and control groups, compared to level walking, and (3) TKA participants would have greater flexion angles, moments and power values at the hip, compared to controls, during the sit-stand tasks. Seventeen participants (age=62±6 years, BMI=30±3 kg/m2, time after surgery=11±5 months) were recruited from the Ottawa Hospital, having undergone unilateral TKA by the same surgeon. An age-matched control group was composed of 17 individuals (age=63±8 years, BMI=27±4 kg/m2) who were recruited from the local community. Three dimensional (3D) biomechanical assessment was conducted with all participants performing five trials of walking on level and inclined surfaces, stair ascent and descent as well as sit-stand tasks. Results from this study were focused on gait and sit-stand transitions, showing that TKA participants exhibited altered gait patterns on both walking surfaces, with significantly smaller knee flexion angles and moments, as well as reduced peak power at the knee. The TKA group also experienced reduced knee extension moments; however, this was only significant for downhill walking. Consistent with our hypothesis, downhill walking resulted in greater discrepancies between the groups compared to level walking. Contrary to our third hypothesis, TKA participants exhibited significantly smaller peak hip flexion angles and moments during the sit-stand task, along with reduced hip abduction angles and knee abduction moments. The reduced knee flexion kinematics and kinetics observed during gait tasks, combined with the differences in frontal plane mechanics observed during the sit-stand task suggest that altered loading patterns persist six to twelve months after surgery. This may be a result of continued pre-operative movement patterns as well as the surgery itself, and should be kept in mind when developing rehabilitation programs for this patient population.

Total knee arthroplasty (TKA) places a large burden on the Canadian Health care system with over 700 million dollars spent on this procedure annually. Exercise has been shown to be effective in improving pain, physical function, mobility and quality of life post-operatively. There is very limited research on adherence to rehabilitation and exercise after TKA. The aim of this thesis was to increase understanding of exercise adherence in this population. The first manuscript in this thesis was a scoping review that evaluated exercise adherence and the quality of reporting of exercise interventions within post-operative TKA rehabilitation trials. A systematic search of scientific databases was conducted for randomized controlled trials (RCT) with an exercise intervention for post-operative TKA. In total, 112 articles were included in this review. This study found that the vast majority of articles (85%) were of poor quality having either high/unclear risk of bias. The majority of RCTs (63%, N=71) on post-operative TKA rehabilitation did not adequately report exercise adherence (e.g., definition, outcome measure used and results), while only 23% (N=15) provided a definition of adherence in the context of their study. Overall reporting of the exercise intervention was poor, with 15 items (of 19) of the Consensus on Exercise Reporting Template (CERT) reported less than 60% of the time. Inadequate reporting of exercise interventions and adherence to exercises leads to decreased reproducibility and translation into clinical practice. Proper reporting of rehabilitation exercises after TKA will ensure standardization for future studies and clinical replication. The second manuscript in this thesis was a qualitative study that aimed to understand the patient- related barriers and facilitators to exercise adherence in patients immediately after undergoing TKA. Using an interpretive description approach, semi-structured qualitative interviews were conducted. Seven participants were interviewed at 8-weeks post-operatively in order to better capture physical, psychological, social and contextual factors linked to exercise adherence. Interview questions explored participants’ experience with physical activity and exercise, motivation to perform physical activity, beliefs that exercise will reduce pain, the factors that limit their ability to engage in exercise, and the importance of using self-regulation to improve exercise adherence. Emergent themes were mapped onto the domains of the WHO adherence framework. This study identified 4 themes that fit within the WHO adherence framework: patient-related factors, condition-related factors, health care system, and social support. In particular, self-regulation, previous knowledge of exercise, post-operative complications, comorbidities, social support, and lack of guidance from health care providers were identified as personal and environmental characteristics that affect exercise adherence. The overall findings of this study suggest exercise adherence is a multifaceted construct with interconnected concepts. / Thesis / Master of Health Sciences (MSc) / Total knee replacement (TKR) surgery costs the Canadian Health care system millions of dollars per year. Exercise is an effective method for improving function and decreasing pain after surgery. However, it is unclear how much patients perform exercise as recommended by health care providers. The purpose of this study was to understand exercise behaviour after knee surgery. The first study was a scoping review that looked at exercise adherence and the characteristics of exercise treatments delivered after knee surgery in previously published clinical trials. The study found that most studies did not report enough information for replication of exercise treatment protocols (e.g. description of provided exercises/progression, who implemented the intervention, etc.). Similarly, exercise adherence was also poorly reported (e.g., definition, how adherence was measured). Poor reporting of exercise treatment methods, and how well participants complete exercises decreases the ability of researchers and therapists to apply the results of these trials. In the second study, patients were interviewed after knee surgery to understand why patients do or do not exercise after surgery. There were several factors, both positive and negative, that patients identified that affected their ability to exercise (e.g. self-regulation (referring to the ability to control thoughts, emotions and behaviour to pursue long-term goals), prior knowledge of exercise, having social support from family and friends, as well as lack of support from health care providers). The overall findings suggest that how well participants exercise after surgery is a complex issue. In order to improve exercise adherence, we need to have a better understanding of the individual factors that may influence adherence.

Introduction: Gait biomechanics are associated with knee osteoarthritis (OA) structural progression, but no studies have included: i) all three lower extremity joints, ii) non-frontal plane factors, iii) temporal loading patterns, and iv) progression from structural and symptomatic perspectives. This dissertation addressed gaps in our understanding of lower limb biomechanics and their implication for determining whether we have identified and are targeting the most effective biomechanical variables in the development and evaluation of conservative interventions to slow knee OA structural and symptom progression (progression to TKA). Methods: 54 patients with knee OA underwent baseline gait analysis. Three-dimensional hip, knee, and ankle angles and moments were calculated. Waveform characteristics were determined using Principal Component Analysis (PCA), and knee adduction moment (KAM) peak and impulse were calculated. At follow-up 5-8 years later, 26 patients reported undergoing total knee arthroplasty (TKA). Unpaired Student’s t-tests detected differences in baseline demographic and gait characteristics between TKA and no-TKA groups. Receiver operating curve analysis determined discriminative abilities of these differences. Stepwise discrimination analysis determined which multivariate combination best classified the TKA group. Logistic regression analysis determined the predictive ability of the multivariate model. Results: There were no baseline differences in clinical and spatiotemporal gait characteristics, but the TKA group showed significant gait biomechanical differences, including higher KAM magnitude (KAMPC1), less difference between early and mid-stance KAM (KAMPC2), higher KAM peak and impulse, reduced early stance knee flexion and late stance knee extension moments (KFMPC2), and reduced stance dorsiflexion moments (AFMPC4). The multivariate discriminant function with the highest classification rate (74.1%) combined KAMPC1, KFMPC2, and AFMPC4, with sensitivity of 84.6 and specificity of 71.4. A one-unit increase in the model score increased risk of progression to TKA six-fold. Conclusion: Higher KAMPC1 scores suggest higher overall loading during gait. Lower KFMPC2 and AFMPC4 scores suggest inability to unload the knee and therefore sustained loading. Interventions reducing overall load and altering patterns of loading (i.e. increase unloading) may reduce risk of progression to TKA. Future research should determine how components of the discriminant model can be altered conservatively, and what impact alterations have on the risk of progression to TKA.

With the increasing advocacy for maintaining a healthy lifestyle in regards to exercise and the average age of the population in the U.S. growing older, there has been an increased incidence of arthritic knee damage as a result of osteoarthritis. Once non-procedural methods of treatment have been exhausted, such as NSAIDs and physical therapy, the most effective therapy to regain previous range of motion and quality of life is total knee arthroplasty (TKA). Additionally, TKA is useful to treat patients with rheumatoid disease once their knees have reached end-stage cartilage damage, although it does not restore function as well in these patients as it does in patients with osteoarthritis. Current technological developments have produced prostheses that mimic physiological movement and allow attachment of components positioned similarly to ligaments in the human knee, providing better longevity and functional recovery from the damaged state. The TKA procedure has become fast-tracked to limit the length of stay for patients and the cost to both the individual and the hospital. Though this change to fast-track procedures has helped limit post-operative complications, such as venous thromboembolism, multiple comorbidities and componentry failure continue to increase the risk of failure or revision of the procedure. With the projected increase in the need for TKAs in the future, it is important to review factors that may influence access and success of this procedure, for example, the effect socioeconomic status has on the ability of different patients to receive quality replacements and experience sustained quality of life. Multiple studies have shown that utilization of TKA differs between low income and high income populations, with racial minority populations undergoing the procedure less often as they represent a greater percentage of low income populations. Interestingly, low income patients report greater improvement in function when compared to high income patients, most likely due to low income patients being admitted with more severe knee damage when compared to the other population. Their satisfaction, along with financial constraints and insurance, are factors that lower the rate of revision for low income populations even though their measured range of motion post-operatively is not as good as that in high income populations on average. Social support has been determined to be a significant factor in determining whether patients will undergo TKA and follow the rehabilitation prescribed to them appropriately. Studies have shown less social support reported from minority groups, but not low income cohorts specifically. Using the current knowledge of the impact these differences in socioeconomic status can have on the outcomes of TKA, can help create healthcare environments which will optimize the success rate of TKA for all patients, regardless of socioeconomic status, and prevent unnecessary strain on the healthcare system due to avoidable post-operative issues. Future studies should determine what policies and procedures can be implemented to help aid patients, such as greater social support, and to support hospitals with limited resources in an effort to improve surgical outcomes.

This thesis is missing pages 98-107, all of which are not in the other copies of the thesis. -Digitization Centre / In total knee arthroplasty with bone defect of the tibia, it was believed that with older designs of tibial tray, both block and stem augments must be used with the tibial tray to improve the knee stability. Obviously, the extended stem causes more difficulties to the surgery as well as more suffering to the patients. Getting rid of the extended stem and still maintaining enough stability is therefore very desirable. The newest tray design, Deltafit Keel tray, which provides much more contact with the human bone structure, may provide enough stability without the extra long stem. The objective in this project is to answer the questions - Is the stem augmentation definitely required alongside the block implant for the cases of bone defect in TKA (Total Knee Arthroplasty) when using the Deltafit Keel tibial tray design? In other words, does the configuration of Deltafit Keel tray with a block provide enough stability in the cases of bone defect? In order to give a reliable answer, three configurations have been studied by conducting both experiments and FEA simulation. The three cases are Deltafit Keel tibial tray only (case 1-no bone defect defect), tray with block augment (case 2-with bone defect assumed) and tray with block and extended stem (case 3-with bone defect assumed). In this study, three commercially available composite bones with isotropic material properties are utilized. For each configuration, the bones are clamped in a testing apparatus and 3000 N static compressive load is imposed on the top surface of the tibia tray at central, medial and lateral locations. In experiment, the strains and displacements at strategically selected locations were measured by strain rosettes (strain gages) and DVRT (Differential Variable Reluctance Transducer) displacement transducers, respectively. In order to simulate the three cases, FE model is established by employing several advanced software including CATIA, True Grid Mesh generator and Abaqus. In order to compare with the experimental results, nine cases (three implant configurations with three different loading positions for each) have been simulated using Abaqus/Standard 6.4. In addition to the nine-case studies, the influence of load offsetting is also investigated by shifting the nodal load along medial-lateral and anterior-posterior directions. It is found that load shifting one node in either direction does not cause significant change in either strain or displacement. Furthermore, FE results of adjacent elements are checked as well and no sudden changes are observed. Since the discrepancy of the output from adjacent elements is negligible, an average value of the elements can be used to represent the output in a small region to compare the experimental strain measured by strain rosettes. Both the experimental data and FEA simulation results lead to the conclusion that comparable stability can be achieved with the configuration of Deltafit Keel tibial tray and a block as compared to the case of Deltafit Keel tray only without bone defect. Moderate improvement of stability, but with significant stress shielding, is found when the extended stem is implanted. For the amount of bone defect and the bone material properties used in this study, the Deltafit Keel tray with a block is the best choice because it is able to provide adequate stability and avoid excessive stress shielding. The loss of a substantial amount of bone to implant an extended stem to trade for the excessive stability may not be worthwhile. Besides, stress shielding is a potential problem which may exist if the extended stem is used. / Thesis / Master of Applied Science (MASc)

Introduction: Studies show that Total Knee Arthroplasty (TKA) is successful for the majority of patients however some continue to experience some functional limitations and anecdotal evidence indicates that stiffness is a common complaint. Some studies have suggested an association between stiffness and functional limitations however there has been no previous work which has attempted to objectively quantify knee joint stiffness following TKA. The purpose of this study was to pilot and evaluate a method for the quantitative evaluation in joint stiffness in replaced knees, OA knees and healthy controls and to explore whether there is an association between stiffness and functional limitations post-TKA surgery. Methods: The first part of the study created a biomechanical model of knee stiffness and built a system from which stiffness could be calculated. A torque transducer was used to measure the resistance as the knee was flexed and extended passively and an electrogoniometer concurrently measured the angular displacement. Stiffness was calculated from the slope of the line relating the passive resistive torque and displacement. The torque and joint angle at which stiffness was seen to increase greatly was also noted. The system was bench tested and found to be reliable and valid. Further tests on 6 volunteers found stiffness calculations to have acceptable intra-day reliability. The second part was conducted on three groups: those with end-stage knee OA (n = 8); those who were 1 year post-TKA (n = 15) and age matched healthy controls (n = 12). Knee range of motion was recorded and participants then completed the WOMAC, the SF-12 and a Visual Analogue Score for stiffness as well as indicating words to describe their stiffness. Four performance based tests – the Timed Up and Go (TUG), the stair ascent/descent, the 13m walk and a quadriceps strength test were also undertaken. Finally, passive stiffness at the affected knee was measured. Results: 100% of OA, 80% of TKA and 58% of controls reported some stiffness at the knee. The OA group reported significantly higher stiffness than the OA or TKA groups. There was no difference in self-reported stiffness between the TKA and control groups. Of the total number of words used to describe stiffness, 52% related to difficulty with movement, 35% were pain related and 13% related to sensations. No significantly differences were found between groups in the objective stiffness measures. Significant differences were found however in threshold flexion stiffness angles between groups. When this angle was normalised, differences between groups were not significant. No significant differences were found between groups in the threshold stiffness torque. Greater self-reported stiffness was found to be associated with worse self-reported function. A higher flexion stiffness threshold angle was associated with slower timed tests of function but also with better quadriceps muscle strength. Conclusions: The results support anecdotal reports that perceived stiffness is a common complaint following TKA but there was no evidence to show that patients with TKA have greater stiffness than a control group. There was however evidence to show that patients’ were unable to distinguish between sensations of stiffness and other factors such as pain. Self-perceived increased stiffness was associated with worse functional performance. Greater stiffness however was not necessarily negative. Stiffness increases earlier in flexion range were associated with better functional performance. These results suggest that an ideal threshold range for stiffness may exist; above which negative perceptions of the knee result in worse function but below which, knee laxity and instability may also result in worse function.

Osteoarthritis (OA) is one of the leading causes of global disability. Surgical intervention in the form of Total Knee Arthroplasty (TKA) has been established as an excellent treatment modality for people with OA who experience joint symptoms that have a substantial impact on their quality of life and are refractory to non-surgical treatment. In the 1970s the concept of implanting TKAs in mechanical alignment (MA) was developed as a compromise to confer mechanical advantage to the prosthesis, ignoring the patient's natural anatomy, to prevent early failure of the implant. Until now, this compromise has not been revisited. Satisfaction following TKA remains inferior to total hip arthroplasty. The cause of this dissatisfaction is not clear. Implant survival is no longer comparable to that of the early designs of TKA, and recent studies have suggested that deviation from neutral alignment does not have the detrimental effect on survivorship as previously thought. In an attempt to improve patient satisfaction following TKA a new technique has been developed whereby the prostheses are implanted in such a way as to recreate the alignment of the knee in the patient's pre-arthritic state. This has been termed natural or kinematic alignment (KA). This thesis examines the impact of KA in TKA with the primary hypothesis that TKA performed utilising KA would lead to improved functional outcome following surgery compared to that of MA. An initial single surgeon proof of concept case series of 25 patients was performed to look at the precision of new patient specific cutting blocks. The results suggested that the cutting blocks were accurate in producing the desired cuts. Following the proof of concept case series, a feasibility study was then performed comparing the new KA technique with the standard MA technique. The feasibility study familiarised the operating surgeons with the new technology in preparation for a Randomised Control Trial (RCT). A prospective blinded RCT was performed to compare the functional outcome of patients implanted with TKA in MA with that of KA. A total of 71 patients undergoing TKA were randomised to either MA (n=35) or KA (n=36). Preand post-operative hip knee ankle (HKA) radiographs were analysed. A number of patient reported outcome measures and functional tests were assessed pre-operatively, 6 weeks, 3 months, 6 months, and at 1 year post-operation. The cutting guides were accurate. There were no statistically significant differences between the MA and KA groups at 1 year. A cohort of post-menopausal women with unilateral osteoarthritis treated with TKA utilising the KA philosophy had dual energy x-ray absorptiometry scans 1.5 years post-operatively using a modified validated densitometric analysis protocol, to assess peri-prosthetic Bone Mineral Density (BMD). The contralateral knee was scanned so that relative bone mineral density could be calculated. Statistical analysis revealed no significant difference in relative peri-prosthetic bone mineral density due to variation in implant position with respect to the Lateral Distal Femoral Angle (LDFA) and the Medial Proximal Tibial Angle (MPTA). There was a significant correlation with overall HKA angle and the relative BMD under the medial side of the tibial tray. KA TKAs appear to have comparable short-term results to MA TKAs with no significant differences in function 1 year post-operatively. Overall HKA angle rather than the individual component position caused change in relative BMD under the tibial tray, therefore aiming for an anatomical joint line may improve kinematics without a detrimental effect on the implant. Further research is required to see if any theoretical long-term functional benefits of KA are realised or if there are any potential effects on implant survival.

Total knee arthroplasty (TKA) is a common surgical procedure for the treatment of patients with pain and immobility as a result of osteoarthritis or rheumatoid arthritis. Pain-related interference, pain and nausea are recovery-limiting in these patients in the immediate postoperative period. Preoperative educational interventions that include pain communication and management information have been shown to decrease pain in joint replacement patients (McDonald & Molony, 2004). This randomized controlled trial compared usual preoperative education to an individually delivered preoperative education program. Participants (N=143) were randomized to intervention or usual care groups during routine preadmission testing. The usual care group received the usual preoperative teaching. The treatment group received the usual care teaching, a booklet containing content specific to symptom management after TKA, an individual teaching session during the preadmission testing visit and a telephone follow-up support call during the week before surgery. The primary outcome for this study was pain-related interference with activity and was measured using the Brief Pain Inventory Interference subscale (BPI-I) (Cleeland et al., 1994) on postoperative day three. Secondary outcomes were pain, nausea and expected postoperative activity and were measured on postoperative days one, two and three. There were no differences between groups in any of the outcomes for this study. BPI-I total scores were 24.4±14.4 in the intervention group and 22.4±15.1 in the usual care group (P=0.5) on the third postoperative day. Overall results demonstrated that although TKA patients had severe postoperative pain and severe nausea, they received inadequate doses of analgesia and anti-emetics. Available evidenced based protocols and practices in the health care environment were not followed Individualizing education content was not sufficient to produce a change in postoperative symptoms for these patients. Further research involving the modification of environmental and system factors affecting the provision of symptom management interventions is warranted.