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No description available.

The purpose of this dissertation was to study the effects of graft pretension in anterior cruciate ligament (ACL) reconstruction through a series of experiments. First, an in vitro study of 5 human knees was conducted to determine if intact joint kinematics could be restored when using the ideal graft - the intrinsic ACL. The ACL tibial insertion site was freed, and pretensions of 0, 10, 20, 30, and 40 N were applied to the ligament using a custom designed load cell connection. Kinematics during a simulated active extension were compared to those of the intact knee. Intact knee kinematics were not restored. Pretensions that best restored tibial anterior/posterior translation and internal/external rotation ranged from 0-40 N. Furthermore, the pretensions that best restored these kinematic variables were widely disparate in two specimens. Second, the in vitro kinematics during a simulated active extension of human and porcine knees were compared and contrasted both prior to and following transection of the ACL. The ACL limited: (1) tibial anterior translation in both species, (2) tibial internal rotation in humans, and (3) tibial external rotation in pigs. Differences in kinematic patterns for tibial internal/external rotation and abduction/adduction between the species was explained by requirements for biped and quadruped stances. Third, the mechanical characteristics of porcine patellar tendon (PT) were investigated by uniaxial tensile testing at two strain rates. Patella-PT-tibia complexes from freshly sacrificed skeletally immature and mature animals were loaded to failure at elongation rates of 20 and 200 mm/min. Both strain rate and skeletal maturity significantly affected failure mode, tangent modulus, and ultimate stress of the tendons, and hence are important considerations in the mechanical evaluation of porcine PT. Fourth, ACL reconstructions were performed using pretensions of 10 or 20 N in an in vivo porcine model with a specially designed load cell/telemetry system to monitor graft load. Graft pretension was seen to increase during fixation with interference screws. Following sacrifice at 4 weeks, tissues were mechanically, histologically, and biochemically analyzed. A pretension of 20 N resulted in a tissue more similar to the intrinsic ACL. / Ph. D.

This thesis examined the change in skeletal muscle architecture with contractile force production, the relationship of architecture with muscle strength parameters and if muscle tendinous tissue stiffness determines in vivo explosive strength (i.e. rate of torque development, RTD). Muscle and tendinous tissue adaptations to contrasting strength training regimes, and the potential capacity of these tissues to adapt following chronic strength training were also explored. Quadriceps femoris fascicle length (FL) decreased, while the pennation angle (PA) increased in a curvi-linearly manner from rest to maximal voluntary contraction (MVC) torque. Consequently, effective physiological cross-sectional area (effPCSA) during MVC was 27% greater than at rest, although effPCSA measured at rest and during MVC had similar correlations to maximal strength. In the earliest phase of contraction, FL, but not PA, was negatively related (R2=0.187) to voluntary RTD. Neither FL nor PA was related to maximal isometric or dynamic strength. Muscle-tendon unit (MTU) and patellar tendon (PT) stiffness were unrelated to voluntary and evoked RTD. Relative PT stiffness was also unrelated to relative RTD, although relative MTU stiffness was related to voluntary RTD (25-55%MVT, R2≤0.188) and evoked RTD (5-50%MVT, R2≤0.194). MTU stiffness increased after sustained-contraction (SCT, +21%), though not explosive-contraction strength training (ECT). PT stiffness increased similarly after ECT (+20%) and SCT (+16%), yet neither induced tendon hypertrophy. SCT produced modest muscle (+8%) and aponeurosis (+7%) hypertrophy. Chronic strength trained (CST: >3 years) males had substantially greater muscle and aponeurosis size, but similar tendon size as untrained controls (UNT) and short-term (12 weeks) strength trained (STT) individuals. Between these groups, at the highest common force, MTU stiffness was indifferent, while PT stiffness was similarly greater in STT and CST than UNT. These results suggest FL and PA have little influence on muscle strength and tendon stiffness has no influence on RTD. Maximum strength negated any qualitative influence of MTU stiffness on in vivo RTD. Component MTU tissues (muscle-aponeurosis vs. external tendon) adapt differentially depending on the strength training regime. Specifically, free tendon appeared to adapt to high magnitude loading, while loading duration is also an important stimulus for the muscle-aponeurosis. However, chronic strength training was not concordant with greater higher force MTU stiffness, and does not further increase higher force PT stiffness beyond the adaptations that occur after 12 weeks of strength training. Finally, no evidence was found for tendon hypertrophy in response to strength training.

BACKGROUND: Osteoarthritis is a leading cause of disability in people of 65 and older. Researches have shown several possible factors leading to knee osteoarthritis development. Patellofemoral joint maltracking has been thought to be associated with or caused edema in the knee; which is thought to be the early signs of osteoarthritis. Hoffa's fat pad is an intra-articular component of knee located under the kneecap. It has also been suggested as one marker for osteoarthritis, when MRI shows a presence of edema in it. Recently, edema in the superolateral region of Hoffa's fat pad has been hypothesized as a distinct signal than the edema on other regions. There is an interest in finding the relation of this superolateral edema with other factors of osteoarthritis development. OBJECTIVE: This thesis research project is aimed to assess the relation of kneecap-thighbone (patellofemoral) joint alignment, femoral trochlea morphology, and patellar height to edema in the superolateral region of Hoffa’s fat pad especially in the population with average age above 65 years old. The hypothesis is that the flatter trochlear morphology and abnormal patella alignment will have higher risk of superolateral edema. METHODS: This is a cross-sectional study using a subset data from Multicenter Osteoarthritis (MOST) study, specifically at 60-month visit. This study measured the patellofemoral measurements (sulcus angle, lateral and medial trochlear inclination angle, trochlear angle, Insall-Salvati ratio, patellar tilt angle, and bisect offset) as the predictor variables, and semiquantitative scoring of MRI edema in superolateral Hoffa’s fat pad as the outcome variable. Logistic regression analyses were performed to find the strongly associated patellofemoral measurements to superolateral Hoffa’s fat pad edema. RESULTS: From the logistic regression analysis, trochlear angle, Insall-Salvati ratio, and bisect offset were highly associated with the superolateral edema. A further analysis, by categorizing the measurements to quartiles, was found that only the highest quartiles of both bisect offset and trochlear angle are associated with superolateral Hoffa’s fat pad edema when compared to the reference quartile. All quartiles of Insall-Salvati ratio are strongly associated with superolateral edema when compared to the reference quartile. CONCLUSION: Current study presents that people above 65 years old with high trochlear angle, extreme lateral patellar translation or bisect offset, and high patella riding have high risk of having superolateral Hoffa’s fat pad edema.

<p>Osnovni cilj rekonstrukcije prednjeg ukr&scaron;tenog ligamenta kolena je dobijanje pune stabilnosti kolena u celom obimu pokreta. Bez obzira na razvoj operativne tehnike i rehabilitacije i dalje postoji jedan broj pacijenata koji nije u potpunosti zadovoljan rezultatom rekonstrukcije prednjeg ukr&scaron;tenog ligamenta kolena, te je potrebno izvr&scaron;iti ponovnu operaciju. Smatra se da je najče&scaron;ći uzrok rane ponovne nestabilnosti lo&scaron;a pozicija kalema, tj. pozicija tunela koja nije na anatomskom mestu. Većina hirurga koji se bave ovom problematikom procenjuju poziciju kalema u golenjači na osnovu standardnih radiograma: prednje-zadnje i bočne projekcije, &scaron;to svakako nije dovoljno precizno. U ekonomski&nbsp; razvijenim zemljama poziciju kalema određuju analizirajući snimke kompjuterizovane tomografije (CT) ili magnetne rezonance (MRI). Prvenstveno zbog smanjenja doze zračenja kojoj se izlažu pacijenti prilikom kompjuterizovane tomografije, ali i iz ekonomskih razloga bilo bi korisno razvijanje jednog lako dostupnog, jeftinog ali preciznog i jednostavnog metoda određivanja položaja kalema u golenjači. Osnovni cilj ovog istraživanja bio je da se dokaže značaj pozicije kalema u golenjači i mogućnost svakodnevne kliničke primene novorazvijenog kompjuterskog programa u cilju određivanja prostorne pozicije kalema u golenjači iz samo dva standardna radiograma. Studija je bila eksperimentalno-prospektivnog karaktera. Eksperimentalni deo istraživanja sproveden je na Fakultetu tehničkih nauka (FTN) u Novom Sadu na Departmanu za proizvodno ma&scaron;instvo gde je na osnovu standardnih RTG snimaka (prednje-zadnje i bočne projekcije) razvijen kompjuterski program za određivanje prostornog položaja kalema u golenjači. U cilju verifikacije novorazvijenog programa realizovano je prostorno određivanje položaja kalema u golenjači obradom standardnih RTG snimaka (prednje-zadnje i bočne projekcije) kod 10 pacijenata kod kojih je izvr&scaron;ena primarna rekonstrukcija prednjeg ukr&scaron;tenog ligamenta kolena. Dobijeni rezultati su upoređeni sa položajem kalema na CT snimcima koji su obezbeđeni za sve pacijente. Na taj način je eksperimentalnim putem utvrđena preciznost novorazvijenog softvera u određivanju prostornog položaja kalema u golenjači. Drugi deo istraživanja bilo je prospektivno kliničko ispitivanje koje je sprovedeno na Klinici za ortopedsku hirurgiju i traumatologiju Kliničkog centra Vojvodine u Novom Sadu. Ispitivanu grupu je činilo 120 pacijenata, oba pola, sa prekidom prednjeg ukr&scaron;tenog ligamenta levog ili desnog kolena. Metodom slučajnog izbora pacijenti su podeljeni u četiri grupe od po 30 pacijenata prema veličini sagitalnog ugla (S) bu&scaron;enja kanala u golenjači (S 60&ordm;-69,9&ordm; i S 70&ordm;-80&ordm;) i prema veličini transverzalnog ugla (T) bu&scaron;enja kanala u golenjači (T 60&ordm;-69,9&ordm; i T 70&ordm;-80&ordm;). Grupa I 30 pacijenata (S 60&ordm;-69,9&ordm; i T 60&ordm;-69,9&ordm;), grupa II 30 pacijenata (S 60&ordm;-69,9&ordm; i T 70&ordm;-80&ordm;), grupa III 30 pacijenata (S 70&ordm;-80&ordm; i T 60&ordm;-69,9&ordm;), grupa IV 30 pacijenata (S 70&ordm;-80&ordm; i T 70&ordm;-80&ordm;). Svi pacijenti su godinu dana nakon operacije pro&scaron;li klinička ispitivanja po bodovnim skalama (Tegner bodovna skala, Lysholm bodovna skala i IKDC standard) i artrometrijska merenja. Rezultati dobijeni merenjem položaja kalema u golenjači, kliničkim ispitivanjima i artrometrijskim merenjima poređani su unutar svake grupe posebno, a izvr&scaron;eno je i poređenje dobijenih rezultata između svih grupa. U ispitivanje su uključeni samo oni pacijenti koji su dali potpisani informisani pristanak da učestvuju u ispitivanju nakon detaljnog upoznavanja sa planiranom procedurom. Svaki pacijent je bio informisan o svrsi i načinu sprovođenja istraživanja, kao i o pregledima i merenjima koja će biti vr&scaron;ena. Statističkom analizom rezultata utvrđeno je da veličina gre&scaron;ke prostornog određivanja položaja kalema u golenjači posle rekonstrukcije prednjeg ukr&scaron;tenog ligamenta kolena novorazvijenim kompjuterskim programom nije statistički značajna, a kompjutersko određivanje položaja kalema u golenjači omogućava iste rezultate kao i CT snimci. Sumiranjem zaključaka nakon sveobuhvatne analize dobijenih rezultata istraživanja, može se zaključiti da pozicija kalema u golenjači posle rekonstrukcije prednjeg ukr&scaron;tenog ligamenta kolena utiče na postoperativni funkcionalni rezultat.</p> / <p>The main goal of reconstruction of the anterior cruciate ligament of the knee is to obtain complete knee stability in the full range of movement. Regardless of the development of operational techniques and rehabilitation, there is still a number of patients who are not completely satisfied with the result of reconstruction of the anterior cruciate ligament, and a re-operation is required. It is believed that the most common cause of the instability is the bad position of the graft, i.e. position of the tunnel that is not at the anatomical place insertion. Most surgeons who deal with this problem evaluate the position of the graft in the tibia based on standard radiograms: anterior-posterior and lateral projections, which is not precise enough. In economically developed countries, the position of the graft is determined by analyzing images of computerized tomography (CT) or magnetic resonance (MRI). Primarily due to a decrease in the radiation dose exposed to patients during computerized tomography, but also for economic reasons, it would be useful to develop an easily accessible, inexpensive but precise and simple method for determining the position of the graft in the tibia. The main goal of this examination was to prove the significance of the position of the graft and the possibility of daily clinical use of the newly developed computer program in order to determine in-space position of the graft in only two standard radiograms. The study was experimental-prospective. The experimental part of the research was conducted at the Faculty of Technical Sciences (FTN) in Novi Sad at the Department of Production Engineering, where a computer program for determining in-space position of the graft in the tibia was developed on the basis of standard RTG images (anterior-posterior and lateral projections). In order to verify the newly developed program, in-space determination of the position of the graft in the tibia by processing standard RTG images (anterior-posterior and lateral projections) was performed in 10 patients in which the primary reconstruction of the anterior cruciate ligament was performed. The obtained results were compared with the position of the grafts on CT images provided to all patients. In this way, the accuracy of newly developed software in determining in-space position of the graft in the tibia was determined experimentally. The second part of the study was a prospective clinical trial conducted at the Clinic for Orthopedic Surgery and Traumatology at the Clinical Center of Vojvodina in Novi Sad. The investigated group consisted of 120 patients, both sexes, with a break of the anterior cruciate ligament of the left or right knee. By random selection, patients were divided into four groups of 30 patients according to the size of the sagital angle (S) of the tunnel drilling in the tibia (S 60&ordm;-69,9&ordm; and S 70&ordm;-80&ordm;) and according to the transversal angle (T) of the drill tunnel in the tibia ( T 60&ordm;-69.9&ordm; and T 70&ordm;-80&ordm;). Group I 30 patients (S 60&ordm;-69.9&ordm; and T 60&ordm;-69.9&ordm;), group II 30 patients (S 60&ordm;-69.9&ordm; and T 70&ordm;-80&ordm;), group III 30 patients (S 70&ordm;-80&ordm; and T&ordm;60&ordm; -69.9&ordm;), group IV 30 patients (S 70&ordm;-80&ordm; and T 70&ordm;-80&ordm;). All of the patients underwent clinical trials by scales (Tegner score scale, Lysholm score scale and IKDC standard) and arthrometric measurements one year after surgery. The results obtained by measuring the position of the graft in the tibia, clinical trials and arthrometric measurements were classified separately in each group, and obtained results were compared between all groups. The study included only those patients who gave signed informed consent to participate in the study after being thoroughly informed about planned procedure. Each patient was informed about the purpose and method of conducting the research, as well as the examinations and measurements to be performed. Statistical analysis of the results showed that the size of the error in measuring in-space determination of the position of the graft in tibia after reconstruction of the anterior cruciate ligament of the knee by a newly developed computer program was not statistically significant, and the computer determination of the position of the graft in the tibia provides the same results as the CT images. Summarizing the conclusions after a comprehensive analysis of the obtained results of the study, it can be concluded that the position of the graft in tibia after reconstruction of the anterior cruciate ligament affects the postoperative functional result.</p>

Musculoskeletal injuries are commonly associated with muscle atrophy as a function of immobilization or change of normal function. For example, injuries to the anterior cruciate ligament (ACL) which may involve ligament reconstruction, results in the "quadriceps avoidance" gait which leads to atrophy of the knee extensormuscles. In these situations it is not clear whether or not the atrophy is associated with loss of specific muscle fibre types with accompanying functional deficits. Such knowledge would be helpful in implementing exercise regimes designed to compensate for loss of particular fibre types. It is believed that isokinetic exercise performed at speeds below 180° per second strengthens type I muscle fibres, and type II fibres at fast speeds. However, there is no evidence to indicate the specific muscle fibre response to different rates of muscle contraction. Identification of muscle fibre type is most directly determined by biopsy technique but is too invasive for a routine measurement. Electromyography median frequency has been used as a non-invasive measure to infer muscle fibre composition in various studies. However, the reliability and accuracy of this technique has been questioned and improvement is necessary. This research was designed to provide a more accurate and reliable protocol for the determination of EMG median frequency which may be used, after validation against more direct biopsy techniques, as a routine method for inferring muscle fibre composition. The investigation also explored the muscular response as measured by EMG median frequency to varying speeds of muscle contraction, fatiguing exercise and atrophy following ACL reconstruction. The ultimate aim of this research was to improve the reliability of the determination of EMG median frequency to enhance its application as a predictor of muscle fibre composition. This provides information which may improve ACL rehabilitation programs designed to restore and prevent specific muscle fibre types loss that have not previously been targeted by current rehabilitation programs. This research was conducted in three studies. Study one determined the stability of the EMG median frequency bilaterally for the quadriceps and hamstrings muscles and identified the mode of contraction associated with the greatest reliability. The strength and EMG median frequency of the vastus lateralis, medial hamstrings and vastus medialis of 55 subjects was determined across 5 speeds from 0° to 240° per second using a Kin-Com isokinetic dynamometer and an EMG data acquisition system. Isometric contraction was found to have the least bilateral discrepancy (4.01% ±3.06) and between trials standard deviation (4.50) in the vastus lateralis, medial hamstrings and vastus medialis. Study two investigated the EMG median frequency changes in the vastus lateralis which occur immediately following different speeds of isokinetic exercise to the point of fatigue in normal subjects. Thirty-four subjects participated in the study, and performed a 90-second period of isokinetic exercise to activate the knee extensors at either 30° or 300° per second. EMG median frequency of the vastus lateralis was determined before, immediately after and 7 minutes after the fatiguing exercise. The percentage drop in EMG median frequency of the vastus medialis was gnificantly (p<0.05) greater after slow speed (27.9%) than fast speed (20.25%) exercise, while no significant difference was found for the percentage drop in extension torque. Full recovery was found 7 minutes after the fatiguing exercise. By reference to previous research showing a relationship between EMG median frequency and muscle fibre type, an increase in activation of type I muscle fibres with slow speed exercise and an increase in type II muscle fibres with fast speed exercise was observed. Study three identified the changes in EMG median frequency following ACL reconstruction and evaluated the bilateral differences in EMG median frequency of the knee muscles. The relationships between EMG median frequency and the measures of knee functional ability, knee muscle strength, age and time since surgery were also investigated. Twelve subjects who had undergone ACL reconstruction using a semitendinosus and gracilis graft 6 to 12 months earlier, participated in the study. EMG median frequency was determined from an 8-second isometric contraction and knee functional ability was assessed using the Cincinnati Rating Scale. Bilateral EMG median frequency shifts were inconsistent among subjects. On the basis of previous research which indicated a relationship between EMG median frequency and fibre type, no consistent pattern of muscular fibre type atrophy subsequent to ACL reconstruction occurred within 6 to 12 months (ranged from -43 to 57 Hz). Additionally, no significant correlations were found between the EMG median frequency and the knee functional score and knee extension and flexion torques, age, time since operation and the bilateral differences in EMG median frequency. The results of this investigation will serve to improve the reliability of EMG median frequency across a range of conditions in which it has been evaluated. Further research is needed to confirm the relationship between EMG median frequency and direct observations of muscle fibre composition to improve the predictive value of this measure. Following this validation it will be possible to evaluate the bilateral EMG median frequency shift to infer the type of muscle fibre atrophy, and use this measure in determining the efficacy of specific rehabilitation programs. In conclusion * An 8-second isometric contraction is recommended for determining EMG median frequency. * EMG median frequency of a muscle decreases significantly more after slow fatiguing exercise than after fast speed fatiguing exercise. * There was no generalised bilateral EMG median frequency shift found in a group of subjects 6 to 12 months following semitendinosus and gracilis graft ACL reconstruction. * The results of this study will serve to improve the reliability of procedures used to determine EMG median frequency under a range of different contractile conditions. The EMG median frequency changes in response to these conditions require further validations with muscle biopsy in future.