B Vanderlei

A new PLLA/PCL copolymer for nerve regeneration

The aim of this study is to evaluate the functional and cell biological applicability of a two-ply nerve guide constructed of a PLLA/PCL (i.e. poly-l-lactide and poly-ε-caprolactone) copolymer. To do so, we performed a cytotoxicity test, a subcutaneous biodegradation test and an in situ implantation study in the sciatic nerve of the rat. The nerve guide copolymer was found to be non-toxic, according to ISO/EN standards, and it showed a mild foreign body reaction and complete fibrous encapsulation after implantation. Onset of biodegradation of the inner layer was seen after one month of implantation. After 18 months of implantation complete fragmentation was observed, as well as a secondary inflammatory response characterized by foreign body giant cell activity and phagocytosis of polymer debris. Recovery of both motor and sensory nerve function was observed in all nerve guides.

Two-ply biodegradable nerve guide: basic aspects of design, construction and biological performance

A synthetic biodegradable nerve guide was constructed of two polymeric layers: an inner microporous layer prepared from a copolymer of L-lactide and epsilon-caprolactone (pore size range 0.5-1 micron) and an outer microporous layer prepared from a polyurethane/poly(L-lactide) mixture (pore size range 30-70 microns). This nerve guide was used to bridge a 7 mm gap in the right sciatic nerve of rats. It enabled the sciatic nerve to regenerate across the gap, forming a new, well-defined nerve that effectively re-established the contact between the proximial and distal nerve end, as effective as an autograft.

Improved healing of microvascular PTFE prostheses by induction of a clot layer: an experimental study in rats.

This study was undertaken to test the hypothesis that the induction of a clot layer on the graft surface of microvascular polytetrafluoroethylene (PTFE) prostheses might improve their healing. PTFE microvascular prostheses (n = 18), mechanically roughened PTFE microvascular prostheses (n = 18), and Chitosan-impregnated PTFE microvascular prostheses (n = 18) (all prostheses: length 1 cm, inside diameter 1.5 mm, fibril length 30 microns) were implanted into the abdominal aortas of rats and were evaluated at 3 days (n = 3), 10 days (n = 3), 3 weeks (n = 6), and 6 weeks (n = 6) with regard to the presence or absence of a clot layer and with regard to the amount of graft healing. All untreated PTFE prostheses were never found to be covered with a clot layer, only scarcely with some platelets, and showed poor neoendothelial healing; even at 6 weeks after implantation, there was only endothelial cell coverage near the anastomotic sides (coverage = 19 +/- 4 percent). The endothelial cells were present directly on the graft surface. In contrast, both the roughened and the Chitosan-impregnated PTFE prostheses were completely covered with a thin clot layer upon implantation and demonstrated significantly better neoendothelial healing (endothelial cell coverage at 6 weeks = 76 +/- 22 percent and 75 +/- 18 percent, respectively; p less than 0.001); moreover, in these prostheses, the endothelial cells were present on a matrix of smooth-muscle cells, which covered the graft surface completely. These results confirm our hypothesis that the induction of a clot layer on the graft surface of microvascular PTFE prostheses improves their healing.(ABSTRACT TRUNCATED AT 250 WORDS)

CORRECTION OSTEOTOMIES OF PHALANGES AND METACARPALS FOR ROTATIONAL AND ANGULAR MALUNION - A LONG-TERM FOLLOW-UP AND A REVIEW OF THE LITERATURE

Correction osteotomies of nine phalanges and six metacarpals for rotational and angular malunion were performed in 15 patients ranging from 20 to 75 years of age and followed a mean period of 4.5 years, ranging from 1 to 11 years. Full correction of the preoperative deformity was achieved in 13 of the 15 patients (87%), bony union in 100%, and no loss of preoperative range of motion was observed, except in one patient who underwent additional arthrodesis. A high satisfaction rate was seen among 13 of the 15 patients. These results underline that osteotomies of phalanges and metacarpals for angular and rotational malunion can have significant functional benefits for the well-being of patients.

Fracture of the thumb sesamoid bone: a report of three cases and a review of the English-language literature

Fracture of the sesamoid bone of the thumb is a rare injury. In this report three additional cases with fracture of an ulnar sesamoid bone of the thumb are reported. The anatomic considerations, the mechanisms of injury, the differential diagnoses, and management are discussed with the English-language literature.

Differentiation of vascular pseudointima under normal and disturbed blood flow conditions: Ultrastructural observations in the rat

SummaryTo study the effect of haemodynamic stress on the morphological differentiation of pseudointima, the ultrastructure of the cells lining normally shaped and aneurysmal polyurethane vascular prostheses implanted into the abdominal aorta of rats was examined. In the normally shaped vascular prostheses the pseudointima was composed of several layers of smooth muscle cells, which varied in differentiation from normal smooth muscle cells to myofibroblasts, and which were lined by a continuous sheet of endothelial cells. In the aneurysmal vascular prostheses, a pseudointima, composed of only layers of smooth muscle cells had developed. Those smooth muscle cells which lined the lumen had a typical morphology: they were polygonal, flat cells of unequal size, with a distinct organelle-free zone, containing myofilaments, at the luminal peripheral cytoplasmic side. The other smooth muscle cells varied in differentiation from normal smooth muscle cells to myofibroblasts. Under severe haemodynamic stresses, such as occur in the aneurysmal vascular prostheses, the regeneration of endothelial cells is impaired and smooth muscle cells undergo morphological changes to form a pseudoendothelial lining.