Biomedical subjects

Giuseppe Milano

Publications and source records attributed to Giuseppe Milano.

13 recordsLinked to original sources

PubMed2007

Arthroscopic rotator cuff repair with and without subacromial decompression: a prospective randomized study.

PURPOSE: Our purpose was to evaluate the role of subacromial decompression in the arthroscopic repair of full-thickness rotator cuff tears in a prospective randomized clinical study. METHODS: Arthroscopic cuff repair was performed in 80 patients with a full-thickness rotator cuff tear. They were divided into 2 groups comprising 40 patients each. In group 1 arthroscopic rotator cuff repair was performed with subacromial decompression. In group 2 the repair was performed without decompression. Rotator cuff tears were repaired via metal suture anchors for tendon-to-bone repair, side-to-side repair, or a combination of the 2 techniques. Results were evaluated by use of the Constant score normalized for age and gender, as well as the Disabilities of the Arm, Shoulder and Hand (DASH) and Work-DASH self-administered questionnaires. On analyzing the results at 2 years' follow-up, we considered the following independent variables: age; gender; dominance; location, shape, area, retraction, and reducibility of cuff tear; fatty degeneration; involvement of subscapularis tendon; treatment of biceps tendon; rotator cuff repair technique; and type of acromion. A univariate and multivariate statistical analysis was performed to determine which variables were independently associated with the outcome. RESULTS: Comparison between the groups did not show significant differences for each variable considered. The overall results for the Constant score were 103.6 points in group 1 and 96.1 points in group 2; those for the DASH score were 18.2 points and 23.1 points, respectively; and those for the Work-DASH score were 23.7 points and 26.2 points, respectively. Univariate and multivariate analysis showed that the following variables significantly and independently influenced the outcome: age; shape, retraction, and reducibility of cuff tear; fatty degeneration; involvement of subscapularis; and repair technique. Subacromial decompression did not influence the outcome significantly for each scoring system considered. CONCLUSIONS: At short-term follow-up, subacromial decompression did not seem to significantly affect the outcome of arthroscopic rotator cuff repair. Longer follow-up studies will be necessary to confirm the clinical relevance of these observations. LEVEL OF EVIDENCE: Level I, randomized controlled trial with no significant difference but narrow confidence intervals.

Aged↗

PubMed2006

Synthetic polymers and biomembranes. How do they interact? Atomistic molecular dynamics simulation study of PEO in contact with a DMPC lipid bilayer.

The understanding of interactions of poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO) with biological interfaces has important technological application in industry and in medicine. In this paper, structural and dynamical properties of PEO at the dimyristoylphospatidylcholine (DMPC) bilayer/water interface have been investigated by molecular dynamics (MD) and steered molecular dynamics (SMD) simulations. The structural properties of a PEO chain in bulk water, at the water/vacuum interface, and in the presence of the membrane were compared with available experimental data. The presence of a barrier for the PEO penetration into the DMPC bilayer has been found. A qualitative estimation of the barrier provided a value equal to approximately 19 kJ/mol, that is, 7 times the value of kT at 310 K.

Dimyristoylphosphatidylcholine↗

PubMed2006

Dynamics of benzene guest inside a self-assembled cylindrical capsule: a combined solid-state 2H NMR and molecular dynamics simulation study.

The reorientational dynamics of benzene-d(6) molecules hosted into the cavity of a cavitand-based, self-assembled capsule was investigated by Molecular Dynamics (MD) simulations and temperature-dependent solid-state (2)H NMR spectroscopy. MD simulations were preliminarily performed to assess the motional models of the guest molecules inside the capsules. An in-plane fast reorientation of the benzene guest around the C(6) symmetry axis (B1 motion), characterized by correlation times of the order of picoseconds, was predicted with an activation barrier ( approximately 8 kJ/mol) very similar to that found for neat benzene in the liquid state. An out-of-plane reorientation corresponding to a nutation of the C(6) symmetry axis in a cone angle of 39 degrees (B2 motion, 373 K) with an activation barrier ( approximately 39 kJ/mol) definitely larger than that of liquid benzene was also anticipated. In the temperature range 293-373 K correlation times of the order of a nanosecond have been calculated and a transition from fast to slow regime in the (2)H NMR scale has been predicted between 293 and 173 K. (2)H NMR spectroscopic analysis, carried out in the temperature range 173-373 K on the solid capsules containing the perdeuterated guest (two benzene molecules/capsule), confirmed the occurrence of the B1 and B2 motions found in slow exchange in the (2)H NMR time scale. Line shape simulation of the (2)H NMR spectral lines permitted defining a cone angle value of 39 degrees at 373 K and 35 degrees at 173 K for the nutation axis. The T(1) values measured for the (2)H nuclei of the encapsulated aromatic guest gave correlation times and energetic barrier for the in-plane motion B1 in fine agreement with theoretical calculation. The experimental correlation time for B2 as well as the corresponding energetic barrier are in the same range found for B1. A molecular mechanism for the encapsulated guest accounting for the B1 and B2 motions was also provided.

Journal Article↗

PubMed2006

Comparison between different femoral fixation devices for ACL reconstruction with doubled hamstring tendon graft: a biomechanical analysis.

PURPOSE: The aim of the present study was to compare the mechanical behavior of some devices used for femoral fixation of doubled hamstring tendon graft in anterior cruciate ligament (ACL) reconstruction when included in a graft fixation complex (GFC). METHODS: An ACL reconstruction was performed on 90 porcine knees. The graft used was the doubled lateral extensor of toes (DLET). Nine different femoral fixation devices were tested and classified according to their fixation mechanism: compression (Bioscrew and RCI screw); expansion (Rigidfix); cortical suspension (Ligament Anchor, EndoButton-CL, and Swing Bridge); cancellous suspension (Linx-HT); and cortical-cancellous suspension (Transfix and Bio-Transfix). All GFC were subjected to a cyclic loading test, then to a load-to-failure test. Graft elongation after 1,000 load cycles, failure load, and stiffness were calculated for each device. RESULTS: Regarding graft elongation, Bioscrew and RCI screws showed the highest mean values. All the other GFC showed no significant differences between them when delta elongation (elongation(1,000 cycles) - elongation(20 cycles)) was considered. For failure load, the highest mean values were observed for Bio-Transfix, Transfix, and Swing Bridge; a homogeneous subset with the lowest mean values was formed by Ligament Anchor, RCI screw, Bioscrew, and Linx-HT. For stiffness, the greatest values were observed for Bio-Transfix, Transfix, and Swing Bridge; all other groups showed no significant differences between them. CONCLUSIONS: Cortical-cancellous suspension fixation seemed to offer the best and most predictable results in terms of elongation, fixation strength, and stiffness. For both compression and suspension, the weakest fixation was attained with cancellous fixation devices. Cortical suspension devices showed a greatly variable mechanical behavior, according to their design. CLINICAL RELEVANCE: Transcondylar devices offer the best structural properties for femoral fixation of doubled hamstring tendon graft in ACL reconstruction.

Animals↗

PubMed2005

Mapping atomistic simulations to mesoscopic models: a systematic coarse-graining procedure for vinyl polymer chains.

The paper introduces a systematic procedure to coarse-grain atomistic models of the largest family of synthetic polymers into a mesoscopic model that is able to keep detailed information about chain stereosequences. The mesoscopic model consists of sequences of superatoms centered on methylene carbons of two different types according to the kind of diad (m or r) they belong to. The corresponding force-field contains three different bonds, six angle and three nonbonded terms. Recently developed analytical potentials, based on sums of Gaussians for bond and angle terms of the mesoscale force field have been used. For the nonbonded part, numerical potentials optimized by pressure-corrected iterative Boltzmann inversion have been used. As test case we coarse-grained an atomistic all-atom model of atactic polystyrene. The proposed mesoscale model has been successfully tested against structural and dynamical properties for different chain lengths and opens the possibility of relaxing melts of high molecular weight vinyl polymers.

Journal Article↗

PubMed2005

A clear-cut experimental method to discriminate between in-plane and out-of-plane molecular transition moments.

A new method to orient organic molecules, based on their absorption as guest of the crystalline nanoporous delta phase of uniaxially stretched syndiotactic polystyrene films, is presented. This molecular alignment method not only allows high degrees of guest orientation to be attained but also orients the planar guest molecules with their smallest cross section nearly parallel to the stretching direction (B) rather than perpendicular (A, as usual for absorption in amorphous polymeric phases). As a consequence, in-plane and out-of-plane transition moment vectors maximize their absorption intensities for light polarization nearly perpendicular and parallel to the stretching direction, respectively. Hence, simple linear dichroism measurements by polarized spectra can allow an easy and clear-cut discrimination between in-plane and out-of-plane guest transition moment vectors.

Crystallography, X-Ray↗

PubMed2005

Evaluation of bone plug and soft tissue anterior cruciate ligament graft fixation over time using transverse femoral fixation in a sheep model.

PURPOSE: To evaluate the mechanical role of bone-anterior cruciate ligament (ACL) graft junction in comparison with primary fixation of the graft. TYPE OF STUDY: Ex vivo controlled biomechanical study. METHODS: An ACL reconstruction was performed on 2 groups of 40 sheep each. The ACL graft was patellar tendon in group 1, and free tendon in group 2. Load-to-failure tests were performed at 1, 2, 3, and 6 months. Each group was divided into 2 subgroups: In subgroup A the femoral fixation devices were removed before testing and in subgroup B they were left in place. RESULTS: At 1 month, structural properties of subgroup 2A were significantly lower than other subgroups. Until the third month, structural properties of each subgroup were significantly lower than normal ACL. Grafts always failed at midsubstance, except for subgroup 2A at 1 month, which pulled out of the femoral tunnel. CONCLUSIONS: Bone plug incorporation was stronger than graft strength at 1 month whereas soft tissue tendon incorporation was not stronger than graft until 2 months. At 3 months, both groups failed at approximately 30% of the native ACL strength, and at 6 months, both groups were nearly equal in terms of load to failure and stiffness. CLINICAL RELEVANCE: High fixation strength and stiffness of ACL graft does not allow earlier return to sports activities.

Animals↗

PubMed2005

Mechanical analysis of fixation methods for anterior cruciate ligament reconstruction with hamstring tendon graft. An experimental study in sheep knees.

This study evaluates the structural properties of the femur-anterior cruciate ligament (ACL) graft-tibia complex, comparing different graft fixation techniques in sheep knees. Four fixation devices were tested both for femoral fixation (Transfix, absorbable screw, RCI screw and Linx-HT) and tibial fixation (bone plug with metal screw, absorbable screw with staple, RCI screw and cancellous screw with spiked washer). The graft used for ACL reconstruction was fresh ovine doubled Achilles tendon (DAT). Femurs and tibias were tested separately. Two mechanical test series were performed on the specimens: a load-to-failure test and a cyclic loading test. On the femoral side, transcondylar screw showed the greatest fixation strength and stiffness and the lowest elongation at cyclic loading. Tibial fixation complexes seemed to have poorer structural properties in comparison to femoral fixation. Among the tibial fixation devices, absorbable screw with staple fixation showed the greatest strength and stiffness. Spiked washer fixation showed the greatest elongation under cyclic loading.

Animals↗

PubMed2004

Anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendon graft in rugby players.

The purpose of this study was to evaluate prospectively the results of anterior cruciate ligament (ACL) reconstruction with doubled hamstring tendon graft in a selected group of 18 rugby players. The graft was fixed with a transcondylar screw (Transfix) on the femur, and with an absorbable interference screw and a metallic staple on the tibia. All the patients followed the same rehabilitation program. Return to sports activities was allowed after 6 months. Follow-up was 2 years in all cases. The athletic level of the patients was rated according to the Tegner scoring system. Clinical results were evaluated using the International Knee Documentation Committee (IKDC) scoring system. Furthermore, an instrumented evaluation of the anterior laxity with a KT-1000 arthrometer, and an isokinetic evaluation were performed 6 and 24 months after surgery. The Tegner mean score at follow-up (8.2) was similar to that prior to injury (8.3). IKDC overall results were normal in ten cases (55.6%), nearly normal in six cases (33.3%), and abnormal in two cases (11.1%). Side-to-side difference of anterior laxity measured with KT-1000 at 6 and 24 months did not show an impairment of knee stability with time. Isokinetic evaluation showed a significant improvement on peak torque both in extension and flexion on comparison between 6- and 24-month measurements. The results reported in this study showed that the use of doubled hamstring tendon graft for ACL reconstruction in athletes that were at risk for high-energy traumas to the knees, such as rugby players, gave normal or nearly normal results in about 90% of the cases. Recovery of muscle strength was almost complete 2 years after surgery, and there was no impairment of knee stability with time.

Adolescent↗

PubMed2004

Arthroscopic versus open treatment of Bankart lesion of the shoulder: a prospective randomized study.

PURPOSE: The purpose of this study was to compare the results of arthroscopic and open repair of isolated Bankart lesions of the shoulder using metallic suture anchors. TYPE OF STUDY: Prospective randomized clinical study. METHODS: Sixty patients with traumatic anterior shoulder instability underwent a surgical repair of an isolated Bankart lesion. The patients were divided into 2 groups of 30 patients each. In group 1, an arthroscopic repair was performed, and in group 2, an open procedure was performed. The groups were homogeneous for gender, age, dominance, number of dislocations, time elapsed between first dislocation and surgery, and pathologic findings. In all cases of both groups, the lesion was repaired using metallic suture anchors carrying nonabsorbable braided sutures. Postoperative rehabilitation was the same for the 2 groups. Two years' follow-up evaluation included Constant and Rowe shoulder scores. Statistical analysis of data was performed using an unpaired t test (significance for P <.05). RESULTS: No recurrence of dislocation of the involved shoulder has been reported in either group. Follow-up Constant and Rowe scores of the 2 groups were not significantly different. The only significant difference seen between the 2 groups was for range of motion evaluation with the Constant score. The mean value for group 1 (39.6 +/- 0.8) was significantly greater (P =.017) than that for group 2 (37.8 +/- 2.0). CONCLUSIONS: Arthroscopic repair with suture anchors is an effective surgical technique for the treatment of an isolated Bankart lesion. Open repair does not offer a significantly better 2-year result in terms of stability, and furthermore, can negatively affect the recovery of full range of motion of the shoulder. LEVEL OF EVIDENCE: Level I.

Adult↗

PubMed2003

E stereoregular 1,1 and 1,3 constitutional units from 1,3-butadiene in copolymerizations catalyzed by a highly hindered c(2) symmetric metallocene.

Unprecedented 1,1 and 1,3 constitutional units from 1,3-butadiene, both presenting only the E configuration of the double bond, have been achieved by copolymerization with ethene, conducted at high temperature and low ethene concentration, when catalyzed by a highly hindered C(2) symmetric metallocene. Ethene/butadiene copolymerizations by this catalyst generally lead to prevailing methylene-1,2-cyclopropane units from butadiene. Polymer microstructures obtained for different comonomer concentrations clearly indicate that the rate-determining step leading to cyclopropanation involves ethene, while that leading to 1,1 and 1,3 constitutional units does not. A general copolymerization scheme and a molecular modeling study of the cyclopropanation reaction are presented. Molecular modeling also indicates that the E stereoselectivity for 1,1 and 1,3 constitutional units can be rationalized, in the assumption that an allyl isomerization of the terminal of the growing chain would occur.

Journal Article↗

PubMed2002

Site chirality as a messenger in chain-end stereocontrolled propene polymerization.

The origin of stereoselectivity in the chain-end controlled syndiospecific polymerization of propene with octahedral Ti-catalysts is unclear. We present a possible mechanism which is based on the site chirality as a messenger of information between the chirality of the chain-end and the chirality of monomer insertion which can operate for secondary propagation. This mechanism could be operative also for the industrially relevant V-based homogeneous catalysts.

Journal Article↗

PubMed2002

Stereoselective cyclopropanation by cyclocopolymerization of butadiene.

An unprecedented cyclopropanation by cyclopolymerization reaction is presented. In particular, catalytic copolymerization processes of ethene and butadiene lead with high trans selectivity to a complete cyclocopolymerization of butadiene units. Ethene-based copolymers including cyclopropane and cyclopentane rings, which can be relevant to polyolefin applications, are obtained with high yields. Several aspects relative to the mechanism of this cyclocopolymerization reaction, including the high stereoselectivity, are discussed.

Journal Article↗