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Mechanical factors have been cited as a primary cause of total knee replacement failure. A hypothesis has been formulated stating that the introduction of a compliant interface into a total knee prosthesis would moderate excessive stresses and strains, thereby, extending joint life. A biocompatable elastomer developed by the Dow Corning Corporation was selected for mechanical evaluation as a cushioning material. Force-strain, impact, and fatigue tests were conducted on several specially designed and fabricated elastomer test shapes. Test results demonstrate that a suitably stiff and dynamically responsive elastomer cushion can be designed to handle repeated physiological knee joint loads. Physiological impacts with cadaver tibias demonstrated significant shock reduction benefits, including peak force reductions of up to 70%, with the addition of different elastomer shapes. Compressive fatigue evaluation of elastomer samples was inconclusive owing to extensive sample wear. As a result configurations or applications where the elastomer can move relative to a rigid surface are not recommended. A new, mechanically contained elastomer shape was designed and tested which greatly reduced wear. Bonding of this new shape to prosthetic joint materials is recommended for further experimental evaluation. / Thesis / Master of Engineering (ME)

Background. Knee injuries such as anterior cruciate ligament injuries (ACL) are common in young female athletes resulting in great medical and personal costs. Both knee valgus and muscle fatigue has been reported to increase the risk of injury, while strength training has been used to reduce the occurrence of knee valgus and injury. However, few data exist on the impact of muscle strength and fatigue on knee valgus. Aim. The study aimed at investigating whether muscle strength affects the presence of knee valgus and if fatigue affects knee valgus differently depending on the level of muscle strength in young female athletes. Methods. Twenty young female athletes, mean age 18,15 (±0,79) years, participated in this study. A unilateral drop jump, video analysed in 2-dimensional, was used to evaluate knee valgus and a one Repetition Maximum (1RM) in squat was used to determine the level of muscle strength. A fatigue protocol was used to achieve muscle fatigue before another unilateral drop jump was performed. The subjects were dichotomised, by the 1 RM according to the median, to analyse ‘weak’ versus ‘strong’ females. Both the right leg (RL) and the left leg (LL) were measured before and after fatigue. Results. No significant differences, in the degree of knee valgus, were found between strong and weak group before (RL, p=0.6, LL, p=0.11), or after (RL, p=0.97, LL p=0.36) fatigue. There was also no significant difference in how fatigue affected knee valgus between strong and weak group (RL, p=0.5, LL, p=0.38). Conclusion. The present study suggests that there is no difference in knee valgus between strong and weakfemale athletes. In addition, fatigue does not seem to have an impact on knee valgus in neitherstrong nor weak females. This study has limited number of subjects and further studies are needed. / Bakgrund. Knäskador såsom främre korsbandsskada (ACL) är vanliga hos unga idrottande kvinnor och bidrar till höga medicinska kostnader och personligt lidande. Knävalgus och muskelutmattning har var för sig visat sig öka risken för knäskador hos kvinnor, medan styrketräning har rapporterats kunna minska förekomsten av knävalgus och risken för skada. Emellertid finns få studier som undersöker effekterna av muskelstyrka och utmattning på knävalgus. Syfte. Studien syftar till att undersöka huruvida styrka påverkar förekomsten av knävalgus och om muskulär trötthet påverkar knävalgus olika beroende på nivå av muskelstyrka hos unga idrottande kvinnor. Metod. Tjugo unga kvinnliga idrottare deltog i studien, ålder 18,15 (±0,79). Ett enbenshopp, vilket filmades med videokamera, användes för att utvärdera knävalgus och en repetition maximum (1RM) i knäböj för att bestämma maximal muskelstyrka. Ett utmattningsprotokoll användes för att åstadkomma muskeltrötthet. Genom att dela styrkevariabeln, 1 RM testet, vid medianen delades försökspersonerna in i två grupper; starka och svaga. Samtliga försökspersoner testade både höger och vänster ben innan och efter utmattning. Resultat. Resultaten visade ingen signifikant skillnad mellan stark och svag grupp gällande graden av knävalgus, i varken höger (p= 0,6) eller vänster (p= 0,97) ben före utmattning. Inte heller var det någon skillnad mellan stark och svag grupp efter utmattning (höger ben, p= 0,11, vänster ben, p= 0,36). Inte heller kunde någon signifikant skillnad konstateras angående utmattningens effekt på knävalgus beroende på styrka, stark/svag (höger ben, p= 0,5, vänster ben, p= 0,38). Slutsats. Sammanfattningsvis verkar det inte föreligga någon skillnad i förekomst av knävalgus mellan starka och svaga individer. Således verkar det som att muskelstyrka saknar betydelse för knävalgus hos unga kvinnliga idrottare. Vidare verkar inte heller utmattning påverka knävalgus hos varken starka eller svaga unga kvinnliga idrottare. Studien har begränsat antal deltagare och fler studier krävs.

Lam, Mak Ham. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 110-131). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Disregard for patient-specific joint-level variability may be related to decreased functional ability, poor implant longevity and dissatisfaction post-TKA. The purpose of this study was to, 1) compare pre and post-implant intraoperative passive knee adduction angle kinematic patterns and characterize the effect of surgical intervention on each pattern, 2) examine the association between passive pre and post-implant knee kinematics measured intraoperatively and dynamic knee kinematics and kinetics pre and post-TKA measured during gait, and 3) compare dynamic post-TKA kinematic and kinetic patterns between patient-specific knee recipients and traditional TKA recipient. Patients received a TKA using the Stryker Precision Knee navigation system capturing pre/post-implant kinematics through a passive range of flexion. One-week prior and 1-year post-TKA patients underwent three-dimensional gait analysis. Knee joint waveforms were calculated according to the joint coordinate system. Principal component analysis (PCA) was applied to frontal plane gait angles, moments and navigation angles. Paired two- tailed t-tests were used to compare principal component (PC) scores between pre and post-implant patterns, and a one-way ANOVA was used to test if post-implant patterns were significantly different from zero. Two-tailed Pearson correlation coefficients tested for associations between navigation and gait PCscores, and an un-paired two-tailed t-test was used to compare PCscores between patient-specific and traditional TKA groups. Six different passive kinematic phenotypes were captured pre-implant. Although some waveform patterns persisted at small magnitudes post-implant (PC1 and PC3: p<0.001), curves remained within the clinically acceptable alignment range through passive motion. A positive correlation was found between navigation adduction angle PC1 and gait adduction moment PC1 pre and post-TKA (p<0.001, r=0.79; p<0.01 r=0.67), and a negative correlation between navigation adduction angle PC1 and gait adduction angle PC1 post-TKA (p=0.03, r=-0.53). The patient-specific group showed significantly lower PC2 scores than the traditional TKA group (p=0.03), describing a lower flexion moment magnitude during early stance phase, possibly representing a functional limitation or non- confidence during gait. These results were an important first step to assess patient- specific approaches to TKA, suggesting possible applications for patient-specific intraoperative kinematics to aid in surgical decision-making and influence functional outcomes.

This longitudinal, descriptive study based on Bandura's self-efficacy theory (1977), examined the effects of educational activities on self-efficacy and of self-efficacy on functional ability in everyday activities in clients undergoing elective, primary, unilateral, total knee arthroplasty (TKA). Educational activities included: attending a joint replacement class and a physical therapy session, performing exercises, and reading educational materials. Other sources of client information were also discussed. Self efficacy was assessed regarding confidence in ability to perform activities required for discharge home. Cronbach's alpha for the self-efficacy scale was .94 (pre-education) and .81 (post-education). Functional ability in everyday activities was operationalized as length of hospital stay, discharge placement, and perceived health status. Perceived health status was assessed using the three-scale Western Ontario McMasters University Osteoarthritis Index (WOMAC). Cronbach's alpha was: pain .85, joint stiffness .76, and physical function .94 (preoperatively); and pain .86, joint stiffness .80, and physical function .94 (postoperatively).Evidence was collected from a convenience sample of 31 participants: (a) when the process of scheduling surgery began; (b) before surgery, after the client had opportunities to participate in educational activities, and (c) approximately six weeks after surgery. The orthopedic surgeon and professional staff reviewed instruments for validity. Five clients reviewed the questionnaires for understandability and readability. Data were analyzed using Pearson r correlation coefficients, independent samples t-tests, analyses of variance and chi-square tests. An alpha level of .05 was designated as significant.Higher self-efficacy scores were associated with more expected benefits, previous TKA, and greater pain relief. Lower self-efficacy scores correlated with greater improvement in self-efficacy. Shorter lengths of hospital stay were associated with greater joint stiffness reduction, younger age and previous TKA. Discharge home was associated with younger age and living with someone else. Participants that were "very sure" of the need for TKA exhibited higher self-efficacy scores than participants that were "unsure". Improved outcomes were not associated with any one type of educational activity.This study highlighted the need for further refinement of context sensitive self-efficacy instruments, more sophisticated means of assessing the impact of an increasing array of information sources and more longitudinal studies with larger sample sizes. / Department of Educational Leadership

Knee osteoarthritis affects approximately 25 million adults. In severe cases, total knee arthroplasty (TKA) is the most common solution. TKA is effective at addressing pain and reducing continued degeneration of articular cartilage. However, effective physical therapy (PT) following TKA is vital for a full functional recovery. Despite the importance of PT, half of patients never achieve a full functional recovery. Decreases in proprioceptive feedback, severe atrophy, and pain inhibition all likely contribute to the variability in effectiveness. Surface electromyography-based biofeedback (sEMGBF) may allow clinicians to address some of these barriers by supplementing proprioceptive feedback and targeting small muscle contractions before eventually increasing the contraction requirement. Using a between group design, we compare the effectiveness of sEMGBF (7) to neuromuscular stimulation (NMES) (6), and a control group (6) in recovery following TKA. Effectiveness was evaluated across 4 metrics (quadriceps strength, range of motion, functional improvement, and quality of life) in a pre-test/post-test fashion. At the statistical level this study suggest that sEMGBF leads to greater improvements in quadriceps strength relative to the NMES and control group. Additionally, visual analysis suggests that sEMGBF may also lead to greater improvements in range of motion, and functional improvement relative to the NMES and control group. The results for quality of life are mixed. Overall, the study provides initial clinical support for the utility of sEMGBF following TKA.

Thesis (M.Tech.: Chiropractic) -Dept. of Chiropractic, Durban Institute of Technology, 2003. xvi, 138 leaves / Knee joint pathologies, in general, are associated with a loss of knee-extensor muscle strength. This weakness has been attributed to arthrogenic muscle inhibition (AMI). Manipulation of the sacroiliac (SI) has been shown to significantly reduce AMI and increase the strength in the quadriceps muscle group. Although both the knee and SI joints have been linked to AMI of the quadriceps muscle group, no studies have been conducted showing that manipulating the tibio-femoral (knee) joint has any effect on quadriceps muscle strength or AMI. The purpose of this study was therefore to verify whether manipulation of the knee (tibio-femoral) joint is as effective as SI joint manipulation in increasing quadriceps muscle strength in PFPS patients. This study also investigated the effect of combining manipulative therapy of the tibio-femoral and SI joints on quadriceps muscle strength in PFPS patients.

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