Background: Knee pain is a common musculoskeletal complaint with an estimated annual population prevalence of 25% in people aged over 55 years. There are many causes of knee pain though osteoarthritis (OA) is one of the most frequent. Not all people with OA, however, have knee pain. There is discordance between pain intensity and disease severity, the reason for which is unknown. Variation in pain sensitivity may be one possible explanation. Quantitative sensory testing (QST) is a non-invasive technique using non-painful and painful stimuli to assess altered sensitivities in the skin and muscle. Little is known, however, about pain sensitivity in people with knee pain and the role of psychosocial factors in relation to pain sensitivity and pain intensity. Intra-articular steroids are a widely used and effective therapy for knee OA though response to treatment varies in both magnitude and duration of response. Pain sensitivity and/or psychosocial factors may explain some of the variation observed in response to treatment. Aims: To determine whether (i) greater sensitivity to stimuli is associated with higher levels of pain intensity in a population-based sample with knee pain, and whether those associations are mediated by psychosocial factors, (ii) there are changes in QST following intra-articular steroid injections in patients with symptomatic knee OA, and (iii) whether psychosocial factors and sensitivity to stimuli at baseline predict change in pain following intervention. Methods: 72 men and women with knee pain were recruited from a population-based cohort. All had QST assessments and completed a range of questionnaire instruments addressing pain intensity and psychosocial factors. QST assessments (including thermal, mechanical, vibration and pressure) were made at the most affected knee and contralateral forearm. Assessments of tender point count, wind-up ratio and diffuse noxious inhibitory control were also performed. Structural equation modelling was used to determine whether associations between QST measures and pain intensity were mediated by a latent psychosocial factor. In a separate open label trial of intra-articular steroid injections, 32 men and women with symptomatic knee OA underwent QST assessments and also completed questionnaires. The assessments were performed at both knees at the baseline visit (prior to injection) and at a post-injection visit 5-15 days later. Changes in QST were assessed using Wilcoxon matched pairs signed-rank with linear regression used to determine baseline QST predictors of change in pain. Results: In the observational study, mechanical hyperalgesia (tender point count, mechanical pain sensitivity, and allodynia), illness perceptions, catastrophizing and disability scores were positively associated with higher levels of pain intensity. Mediation analyses revealed stronger associations for the indirect effect including a latent psychosocial mediator between measures of mechanical hyperalgesia and global pain, and stronger associations for the direct effect between measures of mechanical hyperalgesia and knee pain. In the intervention study no changes in QST were observed between visits. However, lower baseline mechanical pain thresholds at the injected knee and illness perceptions predicted response to treatment. Conclusion: Illness perceptions and mechanical hyperalgesia can be used to identify subjects experiencing higher levels of global and knee pain intensity, and those who were more likely to respond to intra-articular steroid therapy. Changes in knee pain following intervention with steroid injection are not explained by changes in pain sensitivity.

Robotic assisted partial knee arthroplasty (PKA) has gained in popularity as a treatment for end stage knee osteoarthritis (OA) that involves only one or two compartments of the knee over total knee arthroplasty (TKA). PKA surgeries are known for their less invasive and more precise treatment of medial or lateral compartmental (+/- patellofemoral) arthritis, improved postoperative range of motion, greater ligament and bone preservation, and a more natural gait. The Robotic Arm Interactive Orthopedic MAKO Stryker (RIO; MAKO Stryker, Fort Lauderdale, Florida) Robot has significantly improved PKA implant alignment by providing real-time feedback during surgery and improving three-dimensional implant placement accuracy. To assess kinematic differences between robotic assisted PKA and manual technique TKA, a 14-camera optoelectronic motion capture system (Optitrack, NaturalPoint, Corvallis, OR USA) was designed and installed in a hospital hallway to collect patient gait outcomes directly after clinic appointments. This thesis investigates the feasibility and validity results from setting up a motion capture system and its associated reliability when using it in a high traffic clinical environment. The first objective of this thesis was to investigate a total of 26 patients (14 TKA, 12 PKA) that underwent a kinematic gait assessment at 4-time points; preoperatively, and postoperatively (3,6,12 months). At 3 and 6 months postoperatively, the TKA group had improved knee flexion range of motion (ROM) during walking compared to the PKA group. This result was statistically significant (3-month p value =0.042, 6-month p value= 0.048). At 6 months, changes in the knee adduction/abduction angles were also significantly different (p value= 0.023), showing less knee ROM in the frontal plane after a PKA comparable to healthy controls. Despite differences in improvements in joint kinematics during walking between the two groups, these factors did not necessarily correlate with better perceived patient reported outcomes (PROMs). The results obtained from this pilot study display initial feasibility and suggest further research is required on a larger sample size to confirm if PKA surgeries are superior to TKA surgeries in terms of gait function. In conclusion, a repeatable, instrumented gait analysis was setup in a busy orthopedic hallway where reliable data can be collected. / Thesis / Master of Applied Science (MASc) / Robotic assisted partial knee replacements have been gaining popularity in recent years due to the perceived benefits over a total knee replacement such as preserving more bone, faster recovery, and improved walking outcomes. A partial knee replacement can either replace one or both compartments of the knee joint, depending on the level of arthritis in the patient's knee. This thesis investigated the differences in walking ability before and after surgery using a specialized system installed in the hospital to collect data during regularly scheduled appointments. Patients in this study either received a partial knee replacement with the help of a surgical robot, or a regular total knee replacement. The results showed that there is a significant difference in how much the knee moves during walking between patients who had the robot surgery and those who had the usual surgery. However, the patient’s experience and their perception of how well they were doing after surgery were not different between the two surgeries. This study provided valuable insight into the current surgical treatments available for knee arthritis.

The purpose of this integrated review of the literature was to explore the postsurgical infection complications commonly occurring in individuals undergoing total knee replacement surgery, and the relationship of co-morbidities, lifestyle choices, and genetics on the risk for complication. A comprehensive search of the literature focusing on the patient surgical site infection and total knee replacement surgery using the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Medical Literature On-line (MEDLINE). Initial searches revealed 80 results. Upon closer scrutiny, duplicates were removed, as well as those not relevant to infection in total knee arthroplasty. This resulted in a review of 6 articles that fit the inclusion criteria. Inclusion criteria were articles written in the English language and published in scholarly, peer-reviewed, journals from 2009 to present. In addition to published articles, pertinent material from current nursing textbooks was evaluated and chosen to further substantiate the literature results. In cases of knee arthroplasty, diagnoses of obesity and diabetes were discovered to be risk factors for postsurgical infection. The findings of this thesis offer interpretation for nursing practice, research, education, and policy. Implications for nursing research, policy, education and practice are highlighted along with limitations of this integrative review.

When conducting motion analysis using 3-dimensional motion capture technology, errors in marker placement on the knee results in a widely observed phenomenon known as “crosstalk” [1-18] in calculated knee joint angles (i.e., flexion-extension (FE), adduction-abduction (AA), internal-external rotation (IE)). Principal Component Analysis (PCA) has recently been proposed as a post hoc method to reduce crosstalk errors and operates by minimizing the correlation between the knee angles [1, 2]. However, recent studies that have used PCA have neither considered exercises, such as cycling (C) and elliptical training (E), other than gait (G) nor estimated the corrected knee axes following PCA correction. The hypothesis of this study is that PCA can correct for crosstalk in G, C, and E exercises but that subject-specific PCA corrected axes differ for these exercises. Motion analysis of the selected exercises were conducted on 8 normal weight (body mass index (BMI) = 21.70 +/- 3.20) and 7 overweight participants (BMI = 27.45 +/- 2.45). An enhanced Helen Hayes marker set with 27 markers was used to track kinematics. Knee joint FE, AA, and IE angles were obtained with Cortex (Motion Analysis, Santa Rosa, CA) software and corrected using PCA to obtain corrected angles for each exercise. Exercise-specific corrected knee joint axes were determined by finding axes that reproduced the shank and ankle body vectors taken from Cortex when used with the PCA corrected angles. Then, PCA corrected gait axes were used as a common set of axes for all exercises to find corresponding knee angles. Paired t-tests assessed if FE-AA angle correlations changed with PCA. Multivariate Paired Hotelling’s T-Square tests assessed if the PCA corrected knee joint axes were similar between exercises. ANOVA was used to assess if Cortex angles, PCA corrected angles, and knee angles using PCA corrected gait axes were different. Reduced FE-AA angle correlations existed for G (p<0.001 for Cortex and p=0.85 for PCA corrected), C (p=0.01 for Cortex and p=0.77 for PCA corrected), and E (p<0.001 for Cortex and p=0.77 for PCA corrected). Differences in the PCA corrected knee axes were found between G and C (p<0.0014). Then, differences were found between Cortex, PCA corrected, and C and E knee angles using the PCA corrected G axes (p<0.0056). The results of this study suggest that if PCA is used to reduce crosstalk errors in motions other than G then it is recommended to adopt the use of a PCA corrected axes set determined from G to produce the PCA corrected angles.

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During normal walking, the relative motion of the human knee involves flexion/extension, anterior/posterior sliding, and medial/lateral rotation. As well, the knee experiences a complex, dynamic loading curve with a peak of up to seven times body weight. However, most wear testing machines that have been used to evaluate total knee replacement materials are unidirectional and/or apply only static force. This thesis presents an alternate wear testing device capable of simulating the most prevalent motions of the knee, and applying physiologically-correct loading to the material interface. By incorporating a CoCr disc, an UHMWPE block, stepping motors, pneumatic components, computer control, and linear tables in an x-y configuration, the device is capable of quickly screening new and alternative materials to UHMWPE before evaluating them on a much more expensive knee simulator. In addition, flexibility of the device allows programming of many different motion and loading configurations permitting materials testing under only certain circumstances, or evaluating the effects on wear of specific motions. Design rationale, development, validation, and future recommendations are presented. / Master of Science

End-stage osteoarthritis is characterised by pain and reduced physical function, for which total knee arthroplasty (TKA) is recognised to be a highly effective procedure. Post-operative outcome and resultant function however is variable. Many factors are thought to influence outcome; in particular quadriceps muscle strength is one of the strongest predictors of the patient’s ability to perform functional tasks. Muscle atrophy has been shown to account for only a third of the variance in muscle power, the remainder is currently unexplained. In this thesis it is hypothesised that physiological and mechanical factors will affect muscle power post TKA. A new design of prosthesis with an axis of rotation of the knee based on new kinematical observations has been suggested to confer a mechanical advantage to the knee extensor mechanism by lengthening its moment arm, and thus reducing the muscular effort required to extend the knee, however this has not as yet been clinically demonstrated. A strong extensor mechanism is recognised as being paramount to the patients return to functional activity following TKA, but there has been no consideration as to the mechanisms how and to what extent the muscle tissue actually recovers. It is known that muscle satellite cells are essential for the regeneration of skeletal muscle and that these cells are activated following damage, but these have not been considered in relation to recovery from orthopaedic procedures. It is hypothesised that the number of satellite cells in the extensor mechanism will vary in the patient population and will influence muscle recovery. A double blind randomised controlled trial of 212 TKA patients was conducted to compare the new implant design with a traditional model. Patient outcome was assessed at four points over a one year period. The new implant was superior in measures of knee flexion, lower limb power output and by patient report questionnaire (Oxford Knee Score) Two-way ANOVA, p = <0.001 in all cases. Extensor mechanism power was significantly increased between all four assessment points in the new implant group, the control group demonstrating change between the second and third assessment only (p= <0.001). Analysis of the outcome assessments used demonstrated a changing relationship between function and patient report of that function. Regression models demonstrated that patient report of function became more consistent with direct functional assessment as the influence of pain diminished post-operatively. A hierarchical model is presented that highlights the limitation of patient report data in isolation. Muscle satellite cells were isolated from biopsies of the quadriceps muscle of 18 patients at the time of surgery and counted by an immunofluorescent staining technique. The number of satellite cells detected accounted for a third of the postoperative variance in power output (R2 = 36.6%). This was confirmed in another cohort of 11 patients with a more sensitive qPCR technique. It was further found that the activated satellite cells accounted for around two thirds of the change in postoperative power output (R2 = 66.7%). In conclusion, both mechanical and physiological factors have a significant effect on muscle power post total knee arthroplasty.

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