Martti M. Ruuskanen

The Role of Polyglycolic Acid Rods in the Regeneration of Cartilage from Perichondrium in Rabbits

The role of polyglycolic acid (PGA) rods in the regeneration of cartilage from perichondrium was investigated in 12 growing rabbits. The fifth rib cartilage was resected subperichondrially from both sides. A 10 X 1.5 mm self-reinforced polyglycolic acid (SR-PGA) rod was inserted on one side to replace the resected cartilage and the retained perichondrium was sutured around the implant. On the control side the perichondrium was shaped into a tube without an implant. Samples were taken 4, 12, and 20 weeks after operation. Pronounced neocartilage formation was seen on both sides, and had grown to form a tube around the implant. Also new bone formation was seen in 12 and 20 weeks. Foreign body reaction was seen inside the implants in every animal.

Generation of cartilage from auricular and rib free perichondrial grafts around a self-reinforced polyglycolic acid mould in rabbits

The generative potential of free perichondrial grafts from rabbit auricular and rib cartilage around a self-reinforced polyglycolic acid (SR-PGA) rod was examined in eight growing rabbits. A 15 x 15 mm perichondrial graft was dissected away from the posterior side of each auricular cartilage. One graft was wrapped around a 1.1 x 10 mm SR-PGA rod and the other served as a control and was shaped into a tube without an implant. Fifth rib cartilages were then resected subperichondrially on both sides. The remaining perichondrium on the other side was wrapped around a 1.1 x 10 mm SR-PGA rod, while the other served as a control and was shaped into a tube without an implant. All the grafts were placed inside pectoralis major muscles. Grafts were biopsied six weeks postoperatively. Neocartilage formation was seen in all grafts with one exception on both the implant and control sides. It formed a tube-like structure around the implant in four cases after grafting of auricular perichondrium and in three cases after grafting of rib perichondrium. New bone formation was also observed. SR-PGA implants did not seem to disturb the generative potential of perichondrium.

Tissue engineering of bone in muscle by using free periosteal grafts with a self-reinforced polyglycolide membrane scaffold. An experimental study in growing rabbits

Abstract For tissue engineering of predesigned rectangular bone from free tibial and calvarial periosteal grafts, using self-reinforced polyglycolide membrane (SR-PGA) as a scaffold, fourteen growing New Zealand White rabbits were used. In twelve animals, free tibial and calvarial periosteal grafts wrapped around membranes and grafts without membranes were implanted in muscle. In two control animals membranes only were implanted. Follow-up periods were 6 and 12 weeks. Bone formation and tissue reactions were evaluated macroscopically and histologically. Tibial grafts produced bone more often than calvarial grafts (11/12 vs. 5/12). At 6 weeks mature rectangular bone was obtained from tibial grafts with membranes, whereas none was obtained from calvarial grafts with membranes. At 12 weeks, bone ossicles obtained from both types of graft with membranes were clearly smaller than at 6 weeks and the rectangular form was lost. SR-PGA membrane can be used as a scaffold to obtain predesigned rectangular bone from free tibial periosteal grafts in growing rabbits. Transplantation should be performed before resorption occurs.

Polylactide and polyglycolic acid-reinforced coralline hydroxy-apatite for the reconstruction of cranial bone defects in the rabbit

SummaryThe possibility of using coralline hydroxy-apatite in combination with polylactide and polyglcycolic acid instead of a bone graft in the skull region is examinated. Coralline hydroxy-apatite blocks strengthened with a membrane made of a combination of polylactide and polyglycolic acid were inserted into bony defects created in 12 rabbit skulls. The blocks were observed during a follow-up of 12 months. They became fixed to the surrounding bone and no adverse effects or harmful reactions in the nearby tissues could be detected.

Perivascular sympathectomy does not remove adrenergic nerves from distal vessels. The effect of various denervations on the rat saphenous bundle: A histochemical study

It has been claimed earlier that perivascular sympathectomy removes distal adrenergic innervation of the vessels. Based on preliminary results suggesting the contrary, the purpose of this work was to reconsider the denervation effect of perivascular sympathectomy. We operated on 40 rats using different denervation methods mainly to test the effects of perivascular sympathectomy on the distal saphenous vessels of the leg. The operations were performed on the right leg, while the left leg was used as a control. Samples were taken 2 days after the operations for glyoxylic acid-induced fluorescence examination for the histochemical demonstration of adrenergic nerves. Perivascular sympathectomy seemed to remove the adrenergic innervation only from the operated segment of the vessel. There was a short segment of diminished innervation a few millimeters in length just distal to the perivascular sympathectomy while the more distal adrenergic nerves around the vessels appeared to be normal. When the saphenous nerve was cut the adrenergic innervation seemed to disappear for 1 cm and to continue to be diminished at the medial malleolus site. Lumbar sympathectomy did not seem to remove the distal adrenergic nerves around the vessels, but caused only a slight decrease in innervation. It can be concluded that the peripheral adrenergic innervation is apparently normal after perivascular sympathectomy and that the operation does not have the previously assumed denervation effects.

SHAPED REGENERATION OF RABBIT EAR PERICHONDRIUM

The neocartilage that regenerated from the ear perichondrium in 18 growing rabbits was shaped using biodegradable implants. The animals were divided into two groups according to the operation used. In group 1 a self-reinforced polyglycolic acid (SR-PGA) rod was placed inside a perichondrial pocket on the dorsum of the ear and surrounded by blood clot, and in group 2 a flap of ear perichondrium was shaped around an SR-PGA rod. Samples were taken for histological examination six weeks after the operation. Active growth of neocartilage was seen in both groups and the SR-PGA rod had successfully guided the perichondrial regeneration in most of the animals.

Remodelling of rabbit rib cartilages with perichondrial flaps and biodegradable implants

Remodelling of rib cartilages using the regenerative potential of perichondrium and self-reinforced polyglycolic acid (SR-PGA) implants was studied in eight growing rabbits. The 5th rib cartilage was resected subperichondrially on both sides and a 10 × 1.1-mm SR-PGA rod was placed inside the perichondrium on one side while the other served as a control. In one-half of the cases the perichondrium was used as a vascularized flap while in the other half it was used as a non-vascularized flap. Samples were taken 6 weeks postoperatively. Neocartilage formation was observed from vascularized as well as non-vascularized flaps.

Guided perichondrial proliferation with biodegradable, self-reinforced polyglycolic acid implants

The growth of neocartilage derived from perichondrium associated with self-reinforced polyglycolic acid (SR-PGA) implants was studied in ten rabbits. Free perichondrial grafts were taken from the dorsal side of the ear, wrapped and sutured around triangular SR-PGA plates, and implanted into the pectoralis muscles. As a control, a triangular perichondrial sac of the same size was shaped and implanted into the contralateral pectoralis muscles. Six weeks after operation neocartilage was found in each animal on both control and implant sides. The SR-PGA implants had guided the perichondrial potential to form triangular-shaped pieces of neocartilage, whereas the neocartilaginous plates on the control sides had lost their original shape.

Stabilization of anterior thoracoplasty with a resorbable, self-reinforced poly-l-lactic acid rod: an experimental study in rabbits

Thoracoplasty using a self-reinforced, poly-l-lactic acid (SR-PLLA) rod was performed on 14 growing rabbits. The 4th–6th rib cartilages were resected subperichondrially on both sides, preserving the perichondrium, and a transverse sternotomy was performed between the levels of the 3rd and 4th ribs. The caudal part of the sternum was depressed, creating an experimental pectus excavatum, and fixed in this position using a 2 × 30 mm SR-PLLA rod placed trasversally on the sternum and fixed laterally between the 4th and 5th ribs on both sides. A CT examination was performed on each rabbit postoperatively and before killing. Samples were taken 1, 6, and 12 months after the operation. Both CT and clinical findings showed that the experimentally created pectus excavatum had maintained well throughout the experimental period. Regeneration of the resected rib cartilages was observed in every rabbit.

Anterior thoracoplasty stabilized with a resorbable, self-reinforced poly-L-lactide acid plate in the correction of pectus excavatum

Anterior thoracoplasty stabilized with a resorbable, self-reinforced poly-L-lactic acid (SR-PLLA) plate was performed on three children to correct pectus excavatum deformity. The rib cartilages of the deformed region were resected subperichondrally and a transverse sternotomy was performed above the level of the deformed part of the sternum. The deformed sternum was elevated and fixed with a 2.5×8×150-mm SR-PLLA plate placed transversely under the sternum. Recovery of all the patients has been uneventful and no recurrence of the deformity has occurred.