Knee osteoarthritis is a debilitating disease causing pain and disability in adults. Biomechanical factors including obesity, abnormal magnitude and load distribution have been cited to play a role in its initiation and progression with its definite cause being multi-factorial. Total knee arthroplasty has become the treatment of choice for knee osteoarthritis and although the procedure is mostly successful, there are some patients who experience implant failures which necessitates revision surgery. Revision surgery is more complicated and thus there is the need to monitor patients who have undergone TKA so as ensure better outcomes and also address problems much earlier. Objective methods like Radiostereometric Analysis (RSA) has proven to be a good tool at diagnosing these implant failures. Inducible displacement with RSA has the potential to serve as a one-time measure to diagnose implant failures. Previous studies have applied loads to induce motion to the knee in various ways- squatting, exercising and weight-bearing on the affected limb. This was not standardized and caused wide variations in the data. This work looked at refining a device used to apply standardized loads to the knee resulting in a more portable and faster way of applying load to the joint. Gait analysis is used to assess implant function pre and post surgery. Some gait patterns have also been related to implant failure. Previous works have focussed primarily on associations between well-working implants (non-revised patients) and these gait patterns (adduction moments and flexion angles). This work focussed on any differences in the gait patterns between patients who did not undergo revision surgery and those that did. Although most parameter differences did not reach statistical differences, they point to important trends that may explain the causative factors (adduction moments) whiles others may point to the effects of disease progression (external rotation).

Darbo aktualumas: Osteoartritas (OA) senstančioje visuomenėje darosi vis svarbesnė problema. Daugumai žmonių OA – tai sindromas, kurį sudaro sąnarių skausmo, sustingimo ir dėl to prastėjančių funkcijų simptomai ir kuris daro didelę įtaką gyvenimo kokybei (Conaghan & Sharma, 2009). Sergantiems osteoartritu ligoniams pažeidžiamos daugelis gyvenimo sričių: apsitarnavimas, namų ruoša, darbas, laisvalaikis, judėjimas, miegas (Thorstenson, 2007; Sunden et al. ,2007). Siekiant sumažinti skausmą bei pagerinti funkciją pacientams, sergantiems kelių sąnarių osteoartritu, analizavome, kaip skirtingos kineziterapijos programos veikia pacientų skausmą, pusiausvyrą ir šlaunies raumenų jėgą. Tyrimo objektas: skausmo, pusiausvyros ir raumenų jėgos pokyčiai, taikant skirtingas kineziterapijos programas – kineziterapiją vandenyje bei kelių sąnarių mobilizaciją ir kineziterapiją salėje bei TENS. Tyrimo tikslas: Nustatyti skirtingų kineziterapijos programų efektyvumą ligoniams, sergantiems kelio sąnario osteoartritu. Tyrimo uždaviniai: 1. Nustatyti klinikinio rodiklio – kelių sąnarių skausmo stiprumo – kaitą, taikant skirtingas kineziterapijos programas; 2. Nustatyti funkcinių rodiklių: statinės ir dinaminės pusiausvyros bei blauzdą tiesiančių raumenų jėgos kaitą, taikant skirtingas kineziterapijos programas; 3. Nustatyti, kuri kineziterapijos programa veiksmingesnė, mažinant skausmą ir didinant funkciją – pusiausvyrą bei blauzdą tiesiančių raumenų jėgą. Tyrimo hipotezė: Manome, kad taikydami... [toliau žr. visą tekstą] / Problem of study: Osteoarthritis (OA), in an aging society is becoming increasingly important problem. OA, for the majority of people - is a syndrome consisting of joint pain, stiffness and function because of deteriorating symptoms and who have a significant impact on the quality of life (Conaghan & Sharma, 2009). Patients ill with osteoarthritis are vulnerable to many disabilities in different areas of life: self-service, household chores, work, leisure, movement, sleep (Thorstenson, 2007; Sunden e al. 2007). In order to reduce pain and improve function in patients with knee osteoarthritis, we examined how different physical therapy programes are affecting the pain, balance and strength of the thigh muscles of the patients.. Object of study: changes in pain, balance and muscle strength while applying different physical therapy programs - physical therapy in water, knee joint mobilization, physical therapy room and TENS. Aim of study: to determine the effectiveness of various physical therapy programs for patients with knee osteoarthritis. Goals of study: 1. Establish a clinical indicator – change in the intensity of knee pain with different physical therapy programs; 2. Identify the functional characteristics: static and dynamic balance and change in force of the extensor muscles of the thigh, with different physical therapy programs; 3. To establish which physical therapy program is more effective in reducing pain and improving function - balance and power of the extensor... [to full text]

Total knee joint replacements (TKRs) are a commonly used treatment when joint pain becomes a major issue and the function of activities of daily living is impaired. TKRs may last for up to 20 years; however, younger and physically more active patients are receiving TKRs, necessitating increased prosthesis life-time. There has been considerable interest in more cartilage-like materials for the tibial inlay of a TKR. Compliant, rubbery polymers may be a first step towards such a material. In this thesis, finite element analysis (FEA) was utilized to assess the feasibility of polycarbonate urethane (PCU) in a TKR application. Mechanical characterisation of PCU55D and PCU80A was performed in order to better understand the deformation behaviour of these materials. Mechanical test data was then used to tune and validate a hyperelastic material model. In a last step, the material model was applied to a static FE knee model which was used to simulate five discrete loading cases: three gait cycle events, stair climbing and squatting. Contact pressure, contact area and von Mises stress of the PCU inlay were compared to literature and to a standard ultra-high molecular weight polyethylene (UHMWPE) inlay. The contact area of the articulating implant surfaces was on average 345% greater in PCU than in UHMWPE and contact pressure was on average 77% lower in PCU than in UHMWPE. The difference between TKRs simulated with a PCU tibial inlay and those simulated with a UHMWPE inlay increased with increasing flexion angle. The contact pressures measured in TKRs simulated with a PCU tibial inlay were well below values that are expected to cause damage to the polymer, possibly reducing the risk of wear. The contact areas found in TKRs simulated with a PCU tibial inlay were close to what has been reported for the natural knee. Considering the low contact pressures even at high flexion angles, where initial congruency is limited, it may be feasible to design less conforming knee prostheses that still exhibit low contact pressures, allowing for a greater range of motion. The reported results strongly indicate that compliant polymers may offer an opportunity to improve current TKRs. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-08-11 14:59:50.801

Arthroscopic knee surgery can be challenging because there is no intuitive relationship between the arthroscopic image, shown on a screen above the patient, and the camera in the surgeon's hand. As a result, arthroscopic surgeons require extensive training and experience. This thesis describes a computer system to help improve target acquisition in arthroscopy by visualizing the location and alignment of an arthroscope using augmented virtuality. A 3D computer model of the patient's joint (from CT) is shown, along with a model of the tracked arthroscopic probe and the projection of the camera image onto the virtual joint. We performed a user study to determine the effectiveness of this navigated display; the study showed that for novice residents, the navigated display improved target acquisition. However, residents with at least two years of experience performed worse. For surgeons, no effect on performance was found. / Thesis (Master, Computing) -- Queen's University, 2010-11-25 23:29:46.526

No description available.

A suite of silica-undersaturated syenites outcrops along the margins of a monzogranite pluton emplaced in the Knee Lake greenstone belt at Cinder Lake, Manitoba. Alkali-feldspar syenitic pegmatite probably represents a cumulate unit derived from magma that subsequently evolved to fine-grained feldspathoid syenites. This evolution involved an increase in the degree of undersaturation from cancrinite-nepheline syenite to vishnevite syenite. Abundant calcite veinlets, showing a carbonatitic isotopic and trace-element signature, crosscut the pegmatite and are interpreted to have evolved from the syenites. The monzogranite and syenites gave similar radiometric ages (~2.72 Ga), but evidence of fenitization in the former suggests that the syenites are somewhat younger. The emplacement of these rocks was coeval with the collision of the North Caribou and North Superior superterranes during amalgamation of the Superior Province. The observed transition from granitic to alkaline magmatism is interpreted to mark the transition from a collisional to post-collisional tectonic regime.

A computational model for the prediction of articular and backside polyethylene (PE) wear of total knee replacements (TKRs) could enable the optimization of TKRs for the reduction of polyethylene wear, thereby improving the long term success of TKRs. A finite element model was developed for the TKR and the results were implemented in a computational wear model to assess PE wear. The wear factors of Archard’s wear law were identified by implementing the finite element simulation results along with knee simulator wear test results. Archard’s wear law was found to have insufficient accuracy for the purpose of optimization. Therefore, a novel computational wear model was developed by the author based on a theoretical understanding of the molecular behavior of PE. The model predicted result fell within the standard deviation of the independent knee simulator wear test results, indicating a high level of accuracy for the novel computational wear model.

Knee osteoarthritis (OA) is a degenerative joint condition characterized by progressive joint pain, swelling, and loss of muscle and joint function for which there is no known cure. Current research indicates that the most important modifiable risk factor for the development and progression of knee OA is obesity, a condition that is increasingly common in older adults. Established treatment guidelines for knee OA recommend regular exercise for disease management. However, for obese patients weight-bearing exercise elicits large joint forces that can exacerbate symptoms and influence disease progression. Using a new anti-gravity treadmill capable of generating a lifting force called lower body positive pressure (LBPP), obese patients with knee OA can engage in regular physical activity while minimizing joint loading. The aim of this study was to assess the effect of a 12-week, anti-gravity treadmill walking (AGTW) program on knee pain and function in obese older adults with knee OA. The alternate hypothesis was that there would be a difference between Knee Injury and Osteoarthritis Outcome Score (KOOS) results before and after the anti-gravity treadmill walking program. A group of 25 participants with a mean (SD) age of 64.2 (6.1) years and BMI of 33.0 (6.8) kg/m2 completed AGTW twice per week for 12 weeks at a body weight percentage that minimized knee pain. Knee symptoms and function (KOOS), knee pain during full weight-bearing treadmill walking (FTW), isokinetic quadriceps and hamstring muscle strength, cardiovascular fitness (YMCA submaximal cycle ergometer test), general health status (SF-12), and activity level (average daily pedometer readings) were assessed at baseline and following the completion of the 12-week program using paired t-tests and Wilcoxon signed rank sum tests (α = 0.05). Improvements between baseline and outtake were found in all KOOS subscales, as well as hamstring and quadriceps thigh muscle strength. Knee pain during full FWB and AGTW decreased following the 12-week program. No significant differences were found in cardiovascular fitness, SF-12 scores, or average daily pedometer readings. The results of this study suggest that anti-gravity treadmill walking increases thigh muscle strength, reduces knee pain, and increases functional capacity during daily activities, including FTW in older, obese individuals with knee OA. Anti-gravity treadmill technology has the potential to improve the health and functional capacity of at-risk knee OA individuals, and advance current methods of rehabilitation and long-term management of chronic symptomatic knee OA.

No description available.

Kelio sąnario traumų pastaruoju metu gausėja dėl kintančio visuomenės gyvenimo būdo, aktyvių sporto šakų pomėgio, be to, senstant populiacijoms daugėja ir kelio sąnario pažeidimų dėl amžiaus. Todėl svarbu nustatyti Lietuvos gyventojų kelio sąnario pažeidimų dinamiką, amžinius ir lytinius ypatumus, ryšį su kitų kelio sąnario struktūrų pažeidimais; patikslinti meniskų ir blauzdikaulio atraminio paviršiaus morfologinių ypatumų reikšmę kelio sąnario funkcijai ir patologijai. Išanalizavome 2004 pacientų, kuriems dėl traumos ar ligos buvo atlikta artroskopinė kelio sąnario operacija, duomenis. Ištyrėme 95 vyrų ir 40 moterų skeletų ilgųjų kaulų matmenis, taip pat – 39 vyriškos ir 28 moteriškos lyties lavoninės medžiagos individų kelio sąnarių struktūras. Nustatėme, kad kelio sąnario sužalojimai du kartus dažnesni vyrams nei moterims. Vidinis meniskas plyšdavo tris kartus dažniau nei išorinis. Abu meniskai kartu dažniau plyšdavo sąnaryje su pažeistais kelio sąnario raiščiais. Ilgėjant laikui nuo priekinio kryžminio raiščio plyšimo iki raiščių rekonstrukcijos operacijos mažėjo pacientų, kuriems meniskai liko nepažeisti. Nustatėme disko formos lateralinio menisko dažnį, pakinklio raumens sausgyslės vartų plotį abiejų lyčių individams, apskaičiavome vyrų ir moterų kelio sąnarių atraminio paviršiaus plotus ir apkrovas (moterų kelio sąnariai slegiami patikimai stipriau nei vyrų – tai galėtų būti dažnesnės moterų kelio sąnario artrozės priežastis). Per pastaruosius 300 metų spaudimas į... [toliau žr. visą tekstą] / The number of knee joint injuries is increasing because it is fashionable in modern society to participate in active and sometimes dangerous sports. Population is aging and therefore is increasing number of knee problems due to the age. That’s why it is important to know the dynamics of the knee joint injuries in Lithuanian population, the age and sex characteristics, relationship of meniscus injury with the other knee structures; clarify the relationship and importance of meniscus and the morphological characteristics of the tibial bearing surface. We analyzed 2004 patients, with knee problems or injury who underwent an arthroscopic knee surgery. We also examined 95 male and 40 female skeletons, long bone dimensions and 39 male and 28 female cadaver knee joint structures. We found that knee injuries twice more common in males than in females. The medial meniscus tears were three times more often than lateral. Both meniscus ruptures were more often in the knee with damaged ligaments. There was significantly decreased intact meniscus number with increasing time from injury of the anterior cruciate ligament to the ligament reconstruction time. We determined the rate of discoid meniscus among Lithuanian patients, the mean width of the hiatus popliteus of lateral meniscus for both sexes, calculated the load on the knee joint bearing surface area. Female's knee joints had significantly major load than males - that might be the cause of more common knee arthrosis in women.