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)

The results of total knee arthroplasty are inferior in younger patients. The challenge today is therefore to develop designs and concepts that will last at least 25 years. This thesis has evaluated the fixation to bone of modern designs of knee prostheses uring RSA analysis. Coating implant surfaces with hydroxy-apatite have proven to enhance fixation to bone. Addition of screws for fixation of the tibial component enhances the fixation, but has negative side effects such as osteolysis around the screws, in turn leading to a higher risk of component loosening. The magnitude and pattern of migration was studied in a randomized study of uncemented tibial implants coated with hydroxy-apatite with and without additional screw fixation in patients younger than 65 years. The uncemented implants migrated initially more than the cemented implants that constituted the control group. Both uncemented groups stabilized at 3 monthes with no further migration, while the cemented implants showed a continuous migration up to the 2 year follow-up, indicating continuous bone resorption at the implant-bone interface, a fact that might lead to an increased risk of late implant loosening. This may not be a problem in older patients, but may have consequences for long-term fixation in younger patients. There was no difference between the two uncemented groups indicating that screws do not improve fixation. Hydroxy-apatite coated knee implants might be well suited for younger patients. Mobile bearing total knee arthroplasty theoretically uncouples the forces at the implant-bone interface, thus improving fixation of the implant to bone. The magnitude and pattern of migration of a cemented mobile bearing knee arthroplasty and a fixed bearing total knee arthroplasty was compared in a randomized study. The results showed that mobile bearings did not improve fixation. Trabecular metal, a new material recently introduced for total knee arthroplasty, has several theoretical advantages. Trabecular metal tibial implants were evaluated in a randomized study in patients younger than 60 years. The implants displayed the typical migration pattern for uncemented implants with greater migration initially followed by early stabilization. The majority of the trabecular metal implants subsided into the bone with no lift-off. Lift-off has the potential of exposing the interface to joint fluid with the potential risk of bone resorption and late loosening, and is commonly seen in metal-backed implants. The finding of absence of lift-off is regarded beneficial for uncemented fixation. Trabecular metal tibial implants might be suited for younger patients. The optimal mode of fixation of the femoral component is yet to be established. Comparing cemented femoral components with uncemented femoral components in a randomized study in patients younger than 60 years revealed no differences of the magnitude or the pattern of migration. Uncemented femoral component seems equally as good as cemented components in younger patients.

published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

abstract: Falls are the leading cause of fatal and non-fatal injuries in the older adult population with more than 27,000 fall related deaths reported every year[1]. Adults suffering from lower extremity arthritis have more than twice the likelihood of experiencing multiple falls resulting in increased fall-related injuries compared to healthy adults. People with lower extremity end-stage osteoarthritis(KOA), experience a number of fall risk factors such as knee instability, poor mobility, and knee pain/stiffness. At end-stage knee OA, the space between the bones in the joint of the knee is significantly reduced, resulting in bone to bone frictional wearing causing bone deformation. In addition, an impaired stepping response during a postural perturbation is seen in people with OA related knee instability. The most common treatment for end-stage knee osteoarthritis is a surgical procedure called, total knee replacement (TKR). It is known that TKR significantly reduces pain, knee stiffness, and restores musculoskeletal functions such as range of motion. Despite studies concluding that knee OA increases fall-risk, it remains unknown if standard treatments, such as TKR, can effectively decrease fall-risk. Analyzing the compensatory step response during a fall is a significant indicator of whether a fall or a recovery will occur in the event of a postural disturbance and is key to determining fall risk among people. Studies have shown reduced trunk stability and step length, as well as increased trunk velocities, correspond to an impaired compensatory step. This study looks at these populations to determine whether TKR significantly enhances compensatory stepping response by analyzing trunk velocities and flexions among other kinematic/kinetic variable analysis during treadmill induced perturbations and clinical assessments. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2019

As a therapist within the multi-disciplinary setting, one is confronted with a wide array of pathology and diagnoses. Care is taken to optimize treatment outcomes and overall return of function to every patient admitted to the various rehabilitation facilities. Treatment is often standardized to ensure quality care benchmarked against outcome parameters. The aforementioned is also true for medical practitioners, pharmacists and other auxiliary service providers. Research is aimed at improving quality of care, finding and establishing the best practises through all hospitals and care facilities. Medical care has undergone a transformation over the past few decades with a strong emphasis being placed on protocols and procedures. Through applying standardized care, protocols and procedures, the researcher have come to realize that certain denominators within patient care have no prediction or outcome control. After more than a decade of treating patients in various rehabilitation settings the researcher have come to realize that one complaint exists with each and every patient under my care – pain. This was even more evident within the group of joint replacement patients. No two patients presented with the exact same pain profile or pain reports despite various commonalities such as anthropometric data (age, gender, length, mass), surgical procedure, attending physician, care facility, pathway exposure, diagnosis, radiographic findings and pharmaceutical intervention. If all the obvious factors were identical – what accounted for the different pain reports? This question is at the heart of the study – why do pain reports differ in the presence of so many similarities between patients? It soon became apparent that pain is recognized in the organic form. Organic pain can be measured and is expected with injury, illness or surgical intervention. The entire multi-disciplinary team is aware of organic pain and ready to intervene with medication, surgery and a pathway of care. All vigorously record organic pain and adapt treatment according to the pain levels as organic pain is real pain: real pain existing through exposure to real surgical intervention. Still the question remained: if all the factors prior to surgery, during surgery and after surgery were the same, why are patients experiencing and reporting very different pain levels? This question was the catalyst for the research and lead to keen focus during patient interviews. Every patient receiving an educational session prior to surgery had very vivid ideas about the pain they will experience post-operatively. The majority of patients formed pre-conceived notions about pain prior to undergoing surgery. They presented with a clear pain rating of what they expected to feel post-operatively. The pre-conceived pain rating was constructed in almost all the cases after some form of information obtained during consultation with their surgeon or a member of the multidisciplinary team. This pain notion existed as a tangible and measurable rating in the client’s mind prior to undergoing the knee replacement surgery. In select cases perceived pain was constructed as a result of information obtained from family or friends that underwent the same procedure while other clients constructed perceived pain due to a lack of information on the proposed surgery. It became evident that education or lack thereof on surgical interventions played a primary role in the construct of perceived pain. Patients were entering theatres for procedures and already experienced a form of perceived pain. If pain could be constructed prior to experiencing surgical intervention – can perceived pain then translate into actual organic pain and account for the variable pain reports post surgery? Against this backdrop, research was directed at understanding perceived pain and the factors that aid the construction of perceived pain. As education was found to be at the heart of every pain construct, the doctor-patient consultation was evaluated as a core component to ascertain the impact this relationship has on perceived pain. Measurement of perceived pain was also performed to conclude on the impact of this pain form on organic pain. The study is aimed at addressing the variant pain reports that no pathway or procedure can predict and provide for. It is an attempt to validate pain as constructed by the patient that impacts on their post-surgical pain ratings and behaviour. This research might contribute towards existing knowledge and understanding of the influence of doctor-patient interaction as well as the significance of this interaction on pain. As only scant research on perception of pain has been undertaken this research can prove insightful for further studies or as supplement to existing views and opinions. It can also serve as a foundation in developing practices that will manage pain by enhancing doctor-patient interaction in the health setting. / MA, Medical Sociology, North-West University, Vaal Triangle Campus, 2012

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.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences