STUDY ON IMPLANT STABILITY IN CEMENTLESS TOTAL KNEE ARTHROPLASTY

Objetives: Determine the stability of tibial and femoral components of 20 cementless knee arthroplasties with rotating platform. Methods: The 20 patients (20 knees) underwent an analysis of dynamic radiographs with an image amplifier and maneuvers of varus and valgus which were compared to static frontal and lateral radiographs of the knees and analyzed by two experienced surgeons in a double-blind way. Results: We could observe in this study that both methods showed very similar results for the stability of the tibial and femoral components (p<0.001) using the Kappa method for comparison. Conclusion: The tibial component was more unstable in relation to the femoral component in both static and dynamic studies. Level of Evidence IV, Case Series.

Judet quadricepsplasty in the treatment of posttraumatic knee rigidity: Long-term outcomes of 45 cases

BACKGROUND: Posttraumatic knee stiffness is a very debilitating condition. Judet's quadricepsplasty technique has been used for more than 50 years. However, few reports of quadricepsplasty results exist in the literature. METHODS: We report the results of 45 cases of posttraumatic arthrofibrosis of the knee treated with Judet's quadricepsplasty. The results of the procedure were analyzed by measuring the degrees of flexion of the operated knees at different time points (before, immediately after, and late postoperatively). RESULTS: The degree of flexion increased from 33.6 degrees (range, 5-80 degrees) preoperatively to 105 degrees (range, 45-160 degrees) immediately after surgery, followed by a slight fall in the range of motion (ROM) in the late postoperative period, which reached an average of 84.8 degrees. There was no significant correlation between knee strength and the patient's gender, but there was a slight trend of lower strength with age. Although Judet's quadricepsplasty technique dates from more than 50 years ago, it still provides good outcomes in the treatment of rigid knees of various etiologies. In general, all cases showed the same pattern of a small decrease in the ROM in the late postoperative period. CONCLUSION: Judet's quadricepsplasty can increase the ROM of rigid knees. The ROM obtained with the surgery persists long term. (J Trauma. 2012; 72: E77-E80. Copyright (C) 2012 by Lippincott Williams & Wilkins)

Linking origin of the electric field-assisted beta-PbF2 crystallization in lead oxyfluoroborate glasses below T (g) to simultaneous cathode/anode-compensated electrochemical reactions

Full validation of the electrochemical mechanisms so far postulated as driving force of electric field-assisted non-spontaneous crystallization development in given glasses has suffered experimental restrictions. In this work, we looked into origin of this phenomenon in lead oxyfluoroborate glasses, resulting in beta-PbF2 growth even below the corresponding glass transition temperatures, through achieving a systematic study of not only Pt,Ag/Glass/Ag,Pt- but also Pt,Ag/Glass/YSZ:PbF2/Ag,Pt-type cells, where YSZ:PbF2 represents a two-phase system (formed by Y2O3-doped ZrO2 and PbF2). It is demonstrated that crystallization induction in these glasses involves Pb2+ ions reduction at the cathode, the phenomenon being, however, confirmed only when the F- ions were simultaneously also able to reach the anode for oxidation, after assuring either a direct glass-anode contact or percolation pathways for free fluoride migration across the YSZ:PbF2 mixtures. A further support of this account is that the electrochemically induced beta-PbF2 phase crystallizes showing ramified-like microstructure morphology that arises, accordingly, from development of electroconvective diffusion processes under electric field action.

Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials

Abstract Background Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. Methods Systematic review with meta-analysis of efficacy within 1–4 weeks and at follow up at 1–12 weeks after the end of treament. Results 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. Conclusion TENS, EA and LLLT administered with optimal doses in an intensive 2–4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK.

Tradução e validação da escala Knee Society Score: KSS para a Língua Portuguesa

OBJETIVO: Traduzir, adaptar culturalmente e validar o "Knee Society Score" (KSS) para a língua portuguesa e verificar suas propriedades de medida, reprodutibilidade e validade. MÉTODO: Avaliados 70 pacientes de ambos os sexos, em estudo clínico transversal, idade entre 55 e 85 anos, osteoartrose primária submetidos a artroplastia total de joelho, com o questionário KSS pelo avaliador 1 (inglês) e após 30 minutos pelo avaliador 2 (português) no pré- operatório e após três e seis meses de pós-operatório. RESULTADOS: O índice alfa de Cronbach e a diagramação de Bland-Altman não detectaram diferença entre as médias das duas avaliações no pré-operatório (p=1,000), com três meses (p=0,991) e seis meses de pós-operatório (p=0,985) na pontuação do joelho e na nota da função do joelho, p=1,000 nos três períodos. CONCLUSÃO: A versão brasileira do Knee Society Score, o Escore da Sociedade do Joelho, mostrou ser um instrumento de fácil compreensão e aplicação; válido e confiável para medir a pontuação e função do joelho de pacientes brasileiros submetidos a ATJ. Nível de Evidências: Estudos diagnósticos - Nivel de Evidência I, Teste de critérios diagnósticos desenvolvidos anteriormente em pacientes consecutivos (com padrão de referência "ouro" aplicado).

Clinical rearfoot and knee static alignment measurements are not associated with patellofemoral pain syndrome

The aim of the present study was to investigate the association between the patellofemoral pain syndrome and the clinical static measurements: the rearfoot and the Q angles. The design was a cross-sectional, observational, case-control study. We evaluated 77 adults (both genders), 30 participants with patellofemoral pain syndrome, and 47 controls. We measured the rearfoot and Q angles by photogrammetry. Independent t-tests were used to compare outcome continuous measures between groups. Outcome continuous data were also transformed into categorical clinical classifications, in order to verify their statistical association with the dysfunction, and χ2 tests for multiple responses were used. There were no differences between groups for rearfoot angle [mean differences: 0.2º (95%CI -1.4-1.8)] and Q angle [mean differences: -0.3º (95%CI -3.0-2.4). No associations were found between increased rearfoot valgus [Odds Ratio: 1.29 (95%CI 0.51-3.25)], as well as increased Q angle [Odds Ratio: 0.77 (95%CI 0.31-1.93)] and the patellofemoral pain syndrome occurrence. Although widely used in clinical practice and theoretically thought, it cannot be affirmed that increased rearfoot valgus and increased Q angle, when statically measured in relaxed stance, are associated with patellofemoral pain syndrome (PFPS). These measures may have limited applicability in screening of the PFPS development.

Muscular and pulmonary O2 uptake kinetics during moderate- and high-intensity sub-maximal knee-extensor exercise in humans

[EN] The purpose of this investigation was to determine the contribution of muscle O(2) consumption (mVO2) to pulmonary O(2) uptake (pVO2) during both low-intensity (LI) and high-intensity (HI) knee-extension exercise, and during subsequent recovery, in humans. Seven healthy male subjects (age 20-25 years) completed a series of LI and HI square-wave exercise tests in which mVO2 (direct Fick technique) and pVO2 (indirect calorimetry) were measured simultaneously. The mean blood transit time from the muscle capillaries to the lung (MTTc-l) was also estimated (based on measured blood transit times from femoral artery to vein and vein to artery). The kinetics of mVO2 and pVO2 were modelled using non-linear regression. The time constant (tau) describing the phase II pVO2 kinetics following the onset of exercise was not significantly different from the mean response time (initial time delay + tau) for mVO2 kinetics for LI (30 +/- 3 vs 30 +/- 3 s) but was slightly higher (P < 0.05) for HI (32 +/- 3 vs 29 +/- 4 s); the responses were closely correlated (r = 0.95 and r = 0.95; P < 0.01) for both intensities. In recovery, agreement between the responses was more limited both for LI (36 +/- 4 vs 18 +/- 4 s, P < 0.05; r = -0.01) and HI (33 +/- 3 vs 27 +/- 3 s, P > 0.05; r = -0.40). MTTc-l was approximately 17 s just before exercise and decreased to 12 and 10 s after 5 s of exercise for LI and HI, respectively. These data indicate that the phase II pVO2 kinetics reflect mVO2 kinetics during exercise but not during recovery where caution in data interpretation is advised. Increased mVO2 probably makes a small contribution to during the first 15-20 s of exercise.

Hypoxia and the cardiovascular response to dynamic knee-extensor exercise

[EN] Hypoxia affects O2 transport and aerobic exercise capacity. In two previous studies, conflicting results have been reported regarding whether O2 delivery to the muscle is increased with hypoxia or whether there is a more efficient O2 extraction to allow for compensation of the decreased O2 availability at submaximal and maximal exercise. To reconcile this discrepancy, we measured limb blood flow (LBF), cardiac output, and O2 uptake during two-legged knee-extensor exercise in eight healthy young men. They completed studies at rest, at two submaximal workloads, and at peak effort under normoxia (inspired O2 fraction 0.21) and two levels of hypoxia (inspired O2 fractions 0.16 and 0.11). During submaximal exercise, LBF increased in hypoxia and compensated for the decrement in arterial O2 content. At peak effort, however, our subjects did not achieve a higher cardiac output or LBF. Thus O2 delivery was not maintained and peak power output and leg O2 uptake were reduced proportionately. These data are consistent then with the findings of an increased LBF to compensate for hypoxemia at submaximal exercise, but no such increase occurs at peak effort despite substantial cardiac capacity for an elevation in LBF.

Biomechanical modelling of human knee during living activities

The knee joint is a key structure of the human locomotor system. The knowledge of how each single anatomical structure of the knee contributes to determine the physiological function of the knee, is of fundamental importance for the development of new prostheses and novel clinical, surgical, and rehabilitative procedures. In this context, a modelling approach is necessary to estimate the biomechanic function of each anatomical structure during daily living activities. The main aim of this study was to obtain a subject-specific model of the knee joint of a selected healthy subject. In particular, 3D models of the cruciate ligaments and of the tibio-femoral articular contact were proposed and developed using accurate bony geometries and kinematics reliably recorded by means of nuclear magnetic resonance and 3D video-fluoroscopy from the selected subject. Regarding the model of the cruciate ligaments, each ligament was modelled with 25 linear-elastic elements paying particular attention to the anatomical twisting of the fibres. The devised model was as subject-specific as possible. The geometrical parameters were directly estimated from the experimental measurements, whereas the only mechanical parameter of the model, the elastic modulus, had to be considered from the literature because of the invasiveness of the needed measurements. Thus, the developed model was employed for simulations of stability tests and during living activities. Physiologically meaningful results were always obtained. Nevertheless, the lack of subject-specific mechanical characterization induced to design and partially develop a novel experimental method to characterize the mechanics of the human cruciate ligaments in living healthy subjects. Moreover, using the same subject-specific data, the tibio-femoral articular interaction was modelled investigating the location of the contact point during the execution of daily motor tasks and the contact area at the full extension with and without the whole body weight of the subject. Two different approaches were implemented and their efficiency was evaluated. Thus, pros and cons of each approach were discussed in order to suggest future improvements of this methodologies. The final results of this study will contribute to produce useful methodologies for the investigation of the in-vivo function and pathology of the knee joint during the execution of daily living activities. Thus, the developed methodologies will be useful tools for the development of new prostheses, tools and procedures both in research field and in diagnostic, surgical and rehabilitative fields.

A new approach for the dynamic modelling of the human knee

Mathematical models of the knee joint are important tools which have both theoretical and practical applications. They are used by researchers to fully understand the stabilizing role of the components of the joint, by engineers as an aid for prosthetic design, by surgeons during the planning of an operation or during the operation itself, and by orthopedists for diagnosis and rehabilitation purposes. The principal aims of knee models are to reproduce the restraining function of each structure of the joint and to replicate the relative motion of the bones which constitute the joint itself. It is clear that the first point is functional to the second one. However, the standard procedures for the dynamic modelling of the knee tend to be more focused on the second aspect: the motion of the joint is correctly replicated, but the stabilizing role of the articular components is somehow lost. A first contribution of this dissertation is the definition of a novel approach — called sequential approach — for the dynamic modelling of the knee. The procedure makes it possible to develop more and more sophisticated models of the joint by a succession of steps, starting from a first simple model of its passive motion. The fundamental characteristic of the proposed procedure is that the results obtained at each step do not worsen those already obtained at previous steps, thus preserving the restraining function of the knee structures. The models which stem from the first two steps of the sequential approach are then presented. The result of the first step is a model of the passive motion of the knee, comprehensive of the patello-femoral joint. Kinematical and anatomical considerations lead to define a one degree of freedom rigid link mechanism, whose members represent determinate components of the joint. The result of the second step is a stiffness model of the knee. This model is obtained from the first one, by following the rules of the proposed procedure. Both models have been identified from experimental data by means of an optimization procedure. The simulated motions of the models then have been compared to the experimental ones. Both models accurately reproduce the motion of the joint under the corresponding loading conditions. Moreover, the sequential approach makes sure the results obtained at the first step are not worsened at the second step: the stiffness model can also reproduce the passive motion of the knee with the same accuracy than the previous simpler model. The procedure proved to be successful and thus promising for the definition of more complex models which could also involve the effect of muscular forces.

Measurement of the helicity dependence of deuteron photodisintegration for photon energies below 450 MeV

In 1998 a pilot experiment was carried out to study the helicity dependence of photoreaction cross sections using circularly polarized real photons on longitudinally polarized deuterons in a deuterated butanol target. The knowledge of these cross sections is required to test the validity of the Gerasimov-Drell-Hearn sum rule on the deuteron and the neutron. The focus of this thesis is on the results for the differential and total cross sections for the photodisintegration reaction for various photon energies in the range from 200 to 450 MeV using data taken with the detector system DAPHNE. The current understanding of the NN interaction as represented by the calculations by M. Schwamb could be confirmed within the given uncertainties. In addition, the detector DAPHNE has been prepared for the main experiment in 2003. The according work is presented together with results of the quality-test measurements of the renewed detector components.

Deep geometry of subduction below the Andean belt of Colombia as revealed by seismic tomography

In this study new tomographic models of Colombia were calculated. I used the seismicity recorded by the Colombian seismic network during the period 2006-2009. In this time period, the improvement of the seismic network yields more stable hypocentral results with respect to older data set and allows to compute new 3D Vp and Vp/Vs models. The final dataset consists of 10813 P- and 8614 S-arrival times associated to 1405 earthquakes. Tests with synthetic data and resolution analysis indicate that velocity models are well constrained in central, western and southwestern Colombia to a depth of 160 km; the resolution is poor in the northern Colombia and close to Venezuela due to a lack of seismic stations and seismicity. The tomographic models and the relocated seismicity indicate the existence of E-SE subducting Nazca lithosphere beneath central and southern Colombia. The North-South changes in Wadati-Benioff zone, Vp & Vp/Vs pattern and volcanism, show that the downgoing plate is segmented by slab tears E-W directed, suggesting the presence of three sectors. Earthquakes in the northernmost sector represent most of the Colombian seimicity and concentrated on 100-170 km depth interval, beneath the Eastern Cordillera. Here a massive dehydration is inferred, resulting from a delay in the eclogitization of a thickened oceanic crust in a flat-subduction geometry. In this sector a cluster of intermediate-depth seismicity (Bucaramanga Nest) is present beneath the elbow of the Eastern Cordillera, interpreted as the result of massive and highly localized dehydration phenomenon caused by a hyper-hydrous oceanic crust. The central and southern sectors, although different in Vp pattern show, conversely, a continuous, steep and more homogeneous Wadati-Benioff zone with overlying volcanic areas. Here a "normalthickened" oceanic crust is inferred, allowing for a gradual and continuous metamorphic reactions to take place with depth, enabling the fluid migration towards the mantle wedge.

Treatment of knee articular cartilage defects: surgical strategies, results and analysis of factors determining the clinical outcome

Articular cartilage lesions, with their inherent limited healing potential, are hard to treat and remain a challenging problem for orthopedic surgeons. Despite the development of several treatment strategies, the real potential of each procedure in terms of clinical benefit and effects on the joint degeneration processes is not clear. Aim of this PhD project was to evaluate the results, both in terms of clinical and imaging improvement, of new promising procedures developed to address the challenging cartilage pathology. Several studies have been followed in parallel and completed over the 3-year PhD, and are reported in detail in the following pages. In particular, the studies have been focused on the evaluation of the treatment indications of a scaffold based autologous chondrocyte implantation procedure, documenting its results for the classic indication of focal traumatic lesions, as well as its use for the treatment of more challenging patients, older, with degenerative lesions, or even as salvage procedure for more advanced stages of articular degeneration. The second field of study involved the analysis of the results obtained treating lesions of the articular surface with a new biomimetic osteochondral scaffold, which showed promise for the treatment of defects where the entire osteochondral unit is involved. Finally, a new minimally invasive procedure based on the use of growth factors derived from autologous platelets has been explored, showing results and underlining indicatios for the treatment of cartilage lesions and different stages of joint degeneration. These studies shed some light on the potential of the evaluated procedures, underlining good results as well as limits, they give some indications on the most appropriate candidates for their application, and document the current knowledge on cartilage treatment procedures suggesting the limitations that need to be addressed by future studies to improve the management of cartilage lesions.

Intraoperative kinematic evaluation with navigation system and postoperative kinematic evaluation with dynamic RSA of total knee arthroplasty

Restoring a correct implant kinematics and providing a good ligament balance and patellar tracking is mandatory to improve clinical and functional outcome after a Total Knee Replacement. Surgical navigation systems are a reliable and accurate tool to help the surgeon in achieving these goals. The aim of the present study was to use navigation system with an intra-operative surgical protocol to evaluate and determine an optimal implant kinematics during a Total Knee Replacement.