Continuous intraarticular and periarticular levobupivacaine for management of pain relief after total knee arthroplasty: A prospective randomized, double-blind pilot study.

BACKGROUND: Total knee arthroplasty (TKA) can result in major postoperative pain which can impact the recovery and rehabilitation of patients and for this reason the use of a pain-control infusion pumps (PCIP) enhances analgesia for TKA. PURPOSE: To investigate whether a PCIP of levobupivacaine would reduce pain in patients following TKA. METHODS: This was a prospective, randomized, controlled study conducted in 55 patients. Criteria for participation were unilateral TKA for osteoarthritis and no allergies to levobupivacaine. The primary outcomes measured were postoperative pain intensity on Visual Analogue Scale (VAS) score measured at 24 h and 48 h. Other measures included amount of narcotics, presence of adverse events, and length of hospital stay. RESULTS: PCIP-treated patients (n = 28) showed significant reductions in VAS score at any time versus control (p < 0.01). Amount of narcotics, presence of adverse events, and length of hospital stay were significantly less with the PCIP versus control (each p < 0.01). CONCLUSION: The use of a mix of levobupivacaina, ketoral-trometamina, and adrenalin provides a safe and effective means in post-operative pain relief in patients undergoing TKA. LEVEL OF EVIDENCE: Level II therapeutic study.

Simultaneous calorimetric and polarization microscopy investigations of light induced changes over phase transitions in a liquid crystal-napthopyran mixture.

We have studied the specific heat and the thermal conductivity in a 4-(n-octyl)-4'-cyanobiphenyl liquid crystal (LC)-photochromic molecules mixture, before, during, and after the photo-activation of the dispersed photochromic molecules, over both the smectic A-nematic and the nematic-isotropic phase transitions. The evaluation of the specific heat has enabled the determination of the changes of the phase transition characteristics induced by the photochromic molecules photoisomerization, while that of the thermal conductivity could be used to monitor the modifications induced in the average LC molecular orientation. The polarization microscopy imaging of the sample texture constituted a valuable support for the interpretation of the obtained thermal conductivity results.

Dual beam differential photopyroelectric setup for broadband thermal effusivity investigation of glass transitions in polymers.

The behaviour of the thermal effusivity squared over the glass transition in polystyrene is measured over a considerable frequency range using a novel dual beam front detection photopyroelectric configuration, which ensures a very effective processing of the obtained signal. This has enabled the detection of the very small changes taking place in such a parameter, despite the non-favourable sensitivity conditions due to the large mismatch between the thermal effusivities of the pyroelectric transducer and of the sample. The effect of the thermal contact resistance between the sample and the pyroelectric detector is also considered and discussed.

Study of the smecticA-hexaticB phase transition in homeotropic single domain samples of 65OBC liquid crystal by photopyroelectric calorimetry.

The smecticA-hexaticB phase transition was studied in a homeotropic single domain sample and in a non-aligned sample of n-hexyl-4'-n-pentyloxybiphenyl-4-carboxylate liquid crystal compound to probe the effect of different amount of defects on the phase transition. The specific heat, the thermal diffusivity and the enthalpy exchange were monitored over the transition and, at the same time, polarization microscopy observations could be carried out. The transition during the first cooling run was found to be accompanied by a considerably larger defect annealing in the non-aligned sample than in the homeotropic one, but the critical behaviour of the specific heat remained substantially the same.

Study of the refractive index of microscopic glass beads by light-refraction analysis.

The refractive index of submillimeter glass beads has been measured by means of a novel, to our knowledge, procedure with reference liquids that does not require close index matching and therefore avoids the use of toxic compounds for high-index glasses (i.e., n >/= 1.8). The method is based on the analysis of the light refracted by a monolayer of beads in comparison with ray-tracing simulations. For the three different types of glass beads investigated a satisfactory fit is achieved by the assumption of a radial variation of the refractive index inside the beads. This is ascribed to the tensile and compressive stresses originating inside the beads during rapid solidification of the glass.

Birefringence and scattering in highly oriented artificial Kerr media.

We have measured both electric birefringence and polarization-resolved static light scattering at visible wave-lengths in highly oriented aqueous suspensions of shaped microparticles. In these experiments the microparticles were oriented by a high-frequency electric field, and saturation effects were clearly observed in both the Kerr effect and light scattering. The transient dynamics of the Kerr effect was studied and a field-dependent medium response time measured.

Polarization-resolved nondegenerate two-wave mixing in shaped microparticle suspensions.

We observe polarization-resolved coherent beam combination through nondegenerate two-wave mixing in water-glycerol suspensions of shaped polytetrafluoroethylene microparticles. Coherent energy transfer that arises from translational and orientational moving index gratings was observed. A theory for beam combination through nondegenerate two-wave mixing is presented and found to be in excellent agreement with these measurements.

Third-order nonlinearity enhancement in an artificial Kerr medium through bulk intrinsic birefringence.

Laser-induced circular birefringence measurements have been performed on a liquid suspension of polymer microellipsoids in order to study its optical nonlinearity as a function of the host liquid's refractive index n(h). The results show that the large values obtained for the chi1221((3)) term (1.6 x 10(-8) esu for n(h) = 1.330) can be explained with an intrinsic birefringence of the microellipsoids relative to their geometrical axes. The obtained values for the refractive indices are n || = 1.391 and n perpendicular = 1.368.

Polarization-resolved optical phase conjugation in an artificial anisotropic Kerr medium.

Optical phase conjugation by degenerate four-wave mixing has been achieved in a liquid suspension of polymer microellipsoids as a result of light-induced rotational effects. Different polarization configurations of the pump and probe beams have been used, and the resulting conjugate polarization states have been discriminated. The results are discussed in terms of different kinds of particle orientational gratings.