Local infiltration analgesia (LIA) is a new technique for postoperative pain management following knee arthroplasty. LIA involves a long-acting local anesthetic (ropivacaine), a non-steroid anti-inflammatory drug (ketorolac) and epinephrine infiltrated into the knee joint during surgery and injected postoperatively via a catheter. In the first two studies, LIA was compared with placebo in unicompartmental (I) and total (II) knee arthroplasty. Postoperative pain levels, morphine consumption and the incidence of side effects were lower in the LIA groups. In addition, we found a shorter length of hospital stay in the LIA group following unicompartmental knee arthroplasty compared with placebo (I), while the time to home readiness was shorter in the LIA group following total knee arthroplasty (II). In this study, we found that the unbound venous blood concentration of ropivacaine was below systemic toxic blood concentrations in a sub-group of patients. In the third study, LIA was compared with intrathecal morphine for postoperative pain relief following total knee arthroplasty (III). Pain scores and morphine consumption were lower, length of hospital stay was shorter and patient satisfaction was higher in the LIA group. In the final study, we investigated the effect of minimally invasive surgery (MIS) compared with conventional surgery in unicompartmental knee arthroplasty (IV). Both groups received LIA. We found no statistically significant differences in postoperative pain, morphine consumption, knee function, home readiness, hospital stay or patient satisfaction. In conclusion, LIA provided better postoperative pain relief and earlier mobilization than placebo, both in unicompartmental and total knee arthroplasty. When compared to intrathecal morphine, LIA also resulted in improved postoperative pain relief and earlier mobilization. Minimally invasive surgery did not improve outcomes after unicompartmental knee arthroplasty, when both groups received LIA.

Aseptic loosening of the tibial component is an important cause of failure after total knee arthroplasty. Bone destruction often claimed to be caused by the cement makes the revision difficult. In order to treat younger patients, uncemented fixation has been introduced, but the etiology to loosening is multifactorial and only partly known. Early detection of implant migration facilitates research in this field but is difficult using conventional techniques. In this study modified versions of roentgen stereophotogrammetric analysis (RSA) were developed to obtain accurate and standardized evaluations facilitating comparison between prosthetic designs. The method was used to record the efficacy of cemented and uncemented fixation of different designs of the tibial component, to determine the accuracy of scintimetry in the detection of early aseptic loosening, and to analyse the in vivo kinematics of knee arthroplasties with different design and stability between the joint surfaces. Forty-three arthroplasties with comparatively high inherent stability of the joint surfaces were randomized to cemented or uncemented fixation of the tibial component. In all groups micromovements were rather large, but with no differences between the cemented and uncemented components. The preoperative diagnosis (arthrosis OA, n=25; rheumatoid arthritis RA, n=18) did not influence the magnitude of micromotion. 20 arthroplasties with the same design as above but equipped with an intramedullary stem, were randomized to cemented or uncemented fixation in patients with RA. Cement improved the fixation. Uncemented stemmed components displayed micromovements seemingly larger than unstemmed ones. 34 arthroplasties with an unconstrained design of the joint area and fixed to the tibia with four pegs were randomized to cemented or uncemented fixation in patients with OA. When used uncemented 4 screws were added. Compared with previously investigated designs small micromotions were recorded, and especially in the cemented cases. Uncemented components with thin polyethylene inserts displayed larger initial micromotions. The preoperative deformity influenced the direction of the micromotion. 33 knees were followed prospectively with RSA and scintimetry to evaluate any correlation between these methods. Low activity under the tibial component at 2 years implied prosthetic stability, whereas high activity indicated instability or high bone remodelling caused by the preoperative malalignment. The in vivo kinematics in three different designs of knee arthroplasties were analyzed during active flexion and extension without weight-bearing. Each type of prosthesis displayed design-specific abnormalities when compared with a normal material. Pronounced posterior tibial translations were recorded during flexion regardless whether the posterior cruciate ligament had been sacrificed or not. Data from the kinematic and the fixation studies suggest that movements restricted by the design of the joint area are transmitted to the bony interface with design-specific micromotions as the result. Analysis of knee joint kinematics during extension and weight-bearing revealed small alterations compared with non-weight-bearing. Evaluation of the three-dimensional movements in terms of helical axis rotations and translations confirmed the constrained or unconstrained in vivo behaviour of the designs under study. This analysis also facilitated the interpretation of the kinematic behaviour of the prosthetic knees and may be of value in the evaluation of new designs. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 7 uppsatser.</p> / digitalisering@umu

Class of 2017 Abstract / Objectives: The first aim is to assess efficacy of aspirin versus enoxaparin in preventing a venous thromboembolism (VTE) after a total knee arthroplasty (TKA) or total hip arthroplasty (THA) within 30 days after discharge. The second aim is to assess the safety of aspirin versus enoxaparin in preventing major bleeding events after a TKA or THA within 30 days after discharge. Methods: This study was a retrospective cohort study with data obtained from an online Veterans Affairs (VA) hospital database. For analysis, the primary outcome was assessed with a Chi-Square test, and the secondary outcome was reported with descriptive statistics.Results: Results: Demographics for 374 patients (TKA, n = 275; THA, n = 99): 90% male, average age of 65, average body mass index (BMI) of 32, 26% smokers, 72% had a history of hypertension, and 60% had a history of dyslipidemia. VTE events 30 days post-operatively: enoxaparin (n = 2), enoxaparin/aspirin (n = 1), and aspirin (n = 2) (P-value = 0.78). Safety events (major bleeding events): enoxaparin (n = 42), enoxaparin/aspirin (n = 7), and aspirin (n = 4). Conclusions: There was no significant difference between the treatment groups for VTE rate 30 days post- operation. The enoxaparin treatment group had the greatest number of safety events compared to the other groups.

A avaliação funcional após a artroplastia total de joelho (ATJ) tem o intuito de analisar como os resultados alcançados após a cirurgia impactam na qualidade de vida e função dos pacientes. Questionários subjetivos de auto percepção da função são os instrumentos mais utilizados, porém, tendem a superestimar a função física. Os testes de desempenho físico avaliam objetivamente o que o indivíduo é capaz de executar, mas avaliam tarefas isoladas que nem sempre refletem a mobilidade nas atividades de vida diária. Portanto, o objetivo deste estudo foi analisar o quanto a avaliação funcional, que incluiu questionários subjetivos e testes de desempenho físico, permite avaliar as mudanças ocorridas longitudinalmente após a ATJ e permite estabelecer fatores pré e pós-operatórios preditivos da função após um ano de cirurgia. Foi realizado estudo longitudinal prospectivo com 87 sujeitos (62 mulheres), idade 67±7 anos, IMC 33±5 kg/m2, submetidos à ATJ primária unilateral. A avaliação ocorreu no pré-operatório e 3, 6 e 12 meses após a cirurgia. Análise da covariância analisou as mudanças ao longo do tempo e a árvore de classificação e regressão estabeleceu os fatores preditivos. O questionário subjetivo WOMAC-função e os testes de desempenho físico timed up and go (TUG) e teste de caminhada de seis minutos (TC6) aos 12 meses de pós-operatório foram as variáveis primárias. A idade, índice de massa corpórea (IMC), WOMAC-dor, função pré-operatória e força muscular do joelho operado e não operado, tanto pré quanto pós-operatoriamente, foram estabelecidas como variáveis secundárias. Os resultados mostraram que WOMAC e o TUG atingiram platô de evolução aos três meses de pós-operatório, enquanto oTC6 alcançou o platô aos seis meses de pós-operatório. Com relação aos fatores pré- operatórios preditivos da função após 12 meses de cirurgia, indivíduos com TUG <=19 s e idade entre 62 e 70 anos alcançaram melhor pontuação no WOMAC-função. Sujeitos com força dos músculos extensores do joelho não operado >=99 Nm/kg e TC6 >328 m antes da cirurgia percorreram maior distância no TC6. Sujeitos com TUG =421 m no pré-operatório obtiveram melhor desempenho no TUG. Sobre os fatores pós-operatórios preditivos da função, sujeitos com WOMAC-dor < 1,5 pontos, TC6 >=410 m e TUG < 8 s apresentaram melhor pontuação do WOMAC-função. Sujeitos com TUG <9 s e força dos músculos extensores do joelho operado >=113 Nm/kg apresentaram melhor desempenho no TC6. Sujeitos com TC6 >=421 m e força dos músculos flexores do joelho não operado >=47Nm/kg foram mais rápidos na execução do TUG. Concluímos que os questionários subjetivos e os testes de desempenho físico apresentaram diferentes comportamentos de evolução ao longo de um ano de pós-operatório de ATJ. Sujeitos com melhor desempenho físico pré e pós-operatório apresentam melhor pontuação no WOMAC-função após a cirurgia e sujeitos com pior dor pós-operatória apresentaram pior percepção da função no mesmo período. Os fatores de maior predição dos testes de desempenho físico foram a função pré-operatória e a força muscular pré e pós-operatória. / The functional evaluation after total knee arthroplasty (TKA) is intended to analyze how the results achieved by the surgery affect the quality of life and function of patients. Subjective patient-report outcomes measures are the most commonly used instruments, but tend to overestimate physical function. Physical performance tests objectively evaluate what the individual is capable to perform, but evaluate isolated tasks that do not always reflect mobility in activities of daily living. Therefore, this study was aimed to analyze how functional evaluation, which encompassed subjective questionnaires and physical performance tests, enables us to evaluate the changes occurred longitudinally after TKA and to establish pre and post-operative predictive factors of this function one year after surgery. We performed a prospective longitudinal study with 87 individuals (62 women), age 66.9±6.66 years, BMI 32.5±5 kg/m2, submitted to unilateral primary TKA. The evaluation took place in the pre-operative period and 3, 6 and 12 months after surgery. The analysis of covariance assessed the changes over time, whereas the classification and regression tree established the predictive factors by considering the WOMAC-function questionnaire and the physical performance tests Timed Up and Go (TUG) and Six-minute Walk Test (6MWT) at 12 months post-operative as primary variables. Age, body mass index (BMI), WOMACpain, pre-operative function, and knee muscle strength, both pre-operatively and postoperatively, were set up as secondary variables. The results showed that the subjective questionnaires and the TUG tests reached a plateau of evolution at three months post-operative, while the 6MWT tests reached the plateau at six months postoperative. Regarding the pre-operative predictive factors of the function at 12 months after surgery, individuals with TUG<=19.3 seconds, aged between 62 and 70 years achieved a better score in the WOMAC-function one year after surgery. Individuals with non-operated knee extensor muscle strength >=99.43 Nm/kg and 6MWT >328 meters before surgery walked a longer distance in the 6MWT test. Individuals with TUG <12.3 seconds and 6MWT>=421 meters in the pre-operative period achieved better TUG performance. As for the post-operative predictive factors of the function, individuals with WOMAC-pain<1.5 points, 6MWT>=410.2 meters and TUG <7.90 seconds showed better scores of the WOMAC-function. Individuals with TUG<9.44seconds and operated knee extensor muscle strength>=112.8 Nm/kg showed better performance in the 6MWT test. Individuals with 6MWT>=421 meters and non-operated knee flexor strength>=47 Nm/kg were faster in executing the TUG test. We concluded that the subjective questionnaires and the physical performance tests showed different evolutionary behaviors during the first year after the TKA surgery. Individuals with better pre and post-operative physical performance show better scores in the WOMAC-function after surgery, while individuals with worse post-operative pain show worse perception of the function in the same period. The most predictive factors of the physical performance tests were pre-operative function and pre and post-operative muscle strength.

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are relatively new biomedical techniques developed during the last century, which are frequently recommended for patients with joint diseases. In spite of their success and huge popularity, the postoperative failure rates for these procedures remain significant. Migration and micromotion of the implant are the primary indicators of its postoperative stability and many in vitro measurement techniques have been discussed. However, effective, practical methods to measure these metrics in vivo have proven elusive and the evolution of such a technique is the subject of this thesis. An implantable, remotely interrogated electronic system for the in vivo measurement of both micromotion and migration in the axial direction is proposed. The main purpose of the device is to improve the ability of clinicians to assess the longterm stability of orthopaedic implants and also to plan and optimise patients’ rehabilitation protocols. The system is based on a modified form of differential variable reluctance transducer (DVRT) in which the nullpoint of the system set automatically by means of a selfcalibration process. Simulations and preliminary in vitro measurements on the bench show that the selfcalibration algorithm works correctly in spite of component tolerances and initial set up errors, allowing a gross displacement (migration) to be measured with a resolution of 15 �m and a range from 0 to 4 mm, and that the device can measure micromotion with an amplitude as low as 1 �m in the range from 200 �m to 200 �m. Accuracy of less than 10 % are achieved in both micromotion and migration measurements. Prototypes of all the major components and subsystems have been fabricated in CMOS integrated circuit (IC) technology as part of the project. Measurements support the feasibility of constructing an integrated version of the complete system for implantation and in vivo use in the future.

L’objectif de ce travail de thèse était d’évaluer les bénéfices thérapeutiques d’un entraînement par imagerie motrice chez les patients ayant subi une prothèse totale de genou unilatérale. Combiner l’imagerie motrice avec la physiothérapie classique a permis de diminuer la douleur et d’augmenter la force du quadriceps durant la phase aiguë, au 1er mois postopératoire. Durant la phase chronique, au 6ème mois postopératoire, l’imagerie motrice permettrait de corriger l’asymétrie de la marche, d’une part en augmentant la force du quadriceps ipsilatéral et, par conséquent, en accentuant la charge sur le genou opéré, et d’autre part en augmentant la flexion maximale du genou durant la phase oscillante. L’imagerie motrice pourrait également aider les personnes âgées après la prothèse totale du genou à monter les escaliers plus rapidement, en toute sécurité. Cela peut atténuer le risque de chute dans les escaliers et, par conséquent, diminuer la fréquence des blessures graves. En conclusion, intégrer l’imagerie motrice dans les programmes de rééducation après prothèse totale du genou primaire unilatérale est pertinent et prometteur / The primary aim of the present work was to determine the therapeutic benefits of a specific motor imagery training. Combining motor imagery with classical physical therapy was found to be effective in reducing pain and increasing quadriceps strength after total knee arthroplasty during the acute phase at the first month postoperatively. During the chronic phase, at the 6th month postoperatively, motor imagery might contribute to correct the asymmetry of gait by increasing the strength of the ipsilateral quadriceps and, consequently accentuating the weight loading on the operated knee, as well as by improving knee proprioception through an increase in the maximum knee flexion during the swing phase. MI might also help elderly people after total knee arthroplasty to climb stairs more quickly, easily, and safely. This could attenuate the risk of falls on stairs, and consequently decrease the frequency of major injuries. In summary, the integration of motor imagery in clinical rehabilitation programs after primary unilateral total knee arthroplasty is relevant and promising

<p><strong>Syfte</strong>: Syftet var att finna skillnader och samband i self-efficacy (SE) – med avseende på typ av artroplastik, kön och ålder – inför två förflyttningar. Detta för att se vilka patienter som kan vara i större behov av att stärka SE postoperativt.</p><p><strong>Metod:</strong> Studien gjordes på inneliggande patienter som genomgått en höft- eller knäartroplastik. Ett för undersökningen framställt frågeformulär undersökte de 117 deltagarnas SE inför att sätta sig upp på sängkanten samt gå med hjälpmedel. Deltagarna skattade SE inför förflyttningarna första eller andra dagen efter operationen.</p><p><strong>Resultat</strong>: Deltagare som hade genomgått en knäartroplastik skattade signifikant högre SE inför att sätta sig upp på sängkanten än de som hade genomgått en höftartroplastik. Männen skattade signifikant högre SE inför båda momenten jämfört med kvinnorna. Det fanns en låg korrelation mellan stigande ålder och låg SE inför att gå med hjälpmedel.</p><p><strong>Konklusion:</strong> Resultaten tyder på att SE inför förflyttningarna skiljer sig mellan patienter. Detta bör behandlande sjukvårdspersonal ta hänsyn till i ett postoperativt skede för att undvika immobiliseringskomplikationer hos patienterna.</p>

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power.

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.

Traditionally, orthopaedic surgical training has primarily taken place in the operating room. Given the growing trend of decreasing resident work hours in North America and globally due to political mandate, training time in the operating room has generally been decreased. This has led to less operative exposure, teaching, and feedback for orthopaedic surgery residents. To solve this problem, a 3D serious game that was designed for the purpose of training orthopaedic surgery residents the steps comprising the total knee replacement procedure. Real-time, 3D graphical and sound rendering technologies are employed to provide sensory realism ensuring that the knowledge gained within the serious game can be more easily recalled and applied a real world scenario. A usability study to address user perceptions of the game’s ease of use, and the potential for learning and engagement was conducted. Results indicate that the serious game is easy to use, intuitive, and stimulating. / UOIT