Thermotropic cubic and tetragonal phases made of rod-like molecules.

Systematic studies on three dimensionally ordered liquid crystalline phases of different cubic and tetragonal symmetries are presented. The structures of the phases are determined by reconstruction of the electron density distribution from the X-ray diffraction patterns. The known models for electron densities in cubic structures were used whereas a new theoretical model for the structure of the tetragonal phase, which shows good agreement with the experimentally obtained electron densities, was proposed. For the first time a continuous phase transition between three dimensional phases with tetragonal and monoclinic symmetries was observed for an optically pure compound.

Effects of a platelet gel on early graft revascularization after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind, clinical trial.

BACKGROUND: Slow graft healing in bone tunnels and a slow graft ligamentization process after anterior cruciate ligament (ACL) reconstruction are some of the reasons for prolonged rehabilitation. AIMS: The purpose of this study was to determine if the use of platelet gel (PG) accelerates early graft revascularization after ACL reconstruction. METHODS: PG was produced from autologous platelet-rich plasma and applied locally. We quantitatively evaluated the revascularization process in the osteoligamentous interface zone in the bone tunnels and in the intra-articular part of the graft by means of contrast-enhanced magnetic resonance imaging (MRI). RESULTS: After 4-6 weeks, the PG-treated group demonstrated a significantly higher level of vascularization in the osteoligamentous interface (0.33 ± 0.09) than the control group (0.16 ± 0.09, p < 0.001). In the intra-articular part of the graft, we found no evidence of revascularization in either group. CONCLUSION: Locally applied PG enhanced early revascularization of the graft in the osteoligamentous interface zone after ACL reconstruction.

Association between sub-clinical acetabular dysplasia and a younger age at hip arthroplasty in idiopathic osteoarthritis.

This retrospective study was designed to investigate whether sub-clinical acetabular dysplasia, defined by a reduced centre-edge angle of Wiberg, was associated with a younger age at hip arthroplasty in patients with idiopathic osteoarthritis (OA). Fifty-four patients with 69 performed arthroplasties and no previous referral for hip dysplasia were selected from a list of consecutive recipients of hip endoprostheses due to idiopathic OA. The centre-edge angle was measured from standard pelvic radiographs taken a mean of 5.1 years prior to the endoprosthesis operation when there were minimal signs of hip OA. The age at which hip arthroplasty was carried out was compared between those patients with low (20 degrees - 35 degrees ) and those with high (>or= 35 degrees ) centre-edge angles. The mean age at hip arthroplasty was significantly younger in the group with centre-edge angles of 20 degrees - 35 degrees (65.6 years) compared with those with centre-edge angles >or= 35 degrees (69.2 years). These results suggest that sub-clinical acetabular dysplasia was associated with a younger age at hip arthroplasty in idiopathic OA.