Lennart Ohlsén

Perichondrial Potential for Cartilagenous Regeneration

This preliminay investigation was conducted in 2-month-old rabbits. The perichondirum was stripped away from the ear cartilage, and raised as a flap. A segment of the exposed cartilage was then removed and the perichondrial flap was sutured back over the created defect. The other ear served as a control, but there the resection of cartilage included the covering perichondrium. In the first group there was a progressive regeneration of cartilage originating from the perichondrium; in the control study, no new cartilage developed. The chondrogenic activity of the perichondrium of the aural cartilage is thus demonstrated and will be further verified in succeeding experiments.

A clinical comparison of the tendency to capsular contracture between smooth and textured gel-filled silicone mammary implants

The aim of this prospective, controlled clinical investigation was to find out if there is a difference in the capsular contracture rate between silicone implants with a smooth or textured surface as the only difference. Twenty-five women with bilateral mammary hypoplasia underwent mammary augmentation. All got a textured implant on one side and a smooth implant on the other. The implants were placed subglandularly. Follow-up examinations were done on six occasions. Three parameters were used for estimation of the tendency to capsular contracture: (1) the patients opinion on differences in hardness of the breasts, (2) the investigators classification of capsular contracture, and (3) applanation tonometry. At the end of the follow-up period, after 1 year, all parameters showed with no doubt that the breasts augmented with textured implants had a lower tendency to develop contracting capsules than the breasts augmented with smooth implants.

The Pathogenesis of Cauliflower Ear: An Experimental Study in Rabbits

Appreciating an imcomplete understanding of the pathogenesis of cauliflower ear, an experimental study was designed to demonstrate the pathophysiology of this deformity. The investigation was conducted in 2-month-old rabbits. In one ear a collection of blood was placed under the raised perichondrium which was then sutured back in place and the skin closed. In the other ear an equal amount of blood was deposited between the intact perichondrium and skin. In the first study new cartilage developed under the perichondrium, but in the ear in which the blood was left above the surface of the perichondrium-covered cartilage, complete resorption of the clot occurred. The cauliflower ear was thus shown to be generating cartilage, arising from a layer of raised perichondrium which was further stimulated by a sero-sanguinous medium. The subperichondrial hematoma was extensively invaded by chondroblasts within 2 weeks, and over a period of 4 weeks the new tissue gradually changed into more mature cartilage. It was a consistent finding that the separated perichondrium retracted, thus causing the original cartilage to rise and buckle over the hamatoma, similar to the picture observed in the human pathology.

Reconstruction of Articular Cartilage with Free Autologous Perichondrial Grafts

An experimental study in adult rabbits has been performed to find out whether the cartilage forming capacity of the perichondrium could be utilized in reconstruction of articular cartilage. The normal articular cartilage of the glenoid surface of the humero-scapular joint was completely removed. Auricular perichondrium was grafted to cover the exposed bony surface with the active chondrogenic layer of the perichondrial graft facing the joint cavity. The joint was not immobilized but the operated limb was amputated at wrist level to avoid weight bearing. The animals were sacrificed at different time intervals ranging from 1 to 17 weeks. In 12 out of 14 grafted rabbits regeneration of cartilage occurred. In 6 of 10 control cases where no perichondrium was grafted to cover the resected surface no cartilage was found. In the other 4, only small areas of mature cartilage were seen, probably remnants of the original articular cartilage.

Tracheal Reconstruction with Perichondrial Grafts: An Experimental Study

Since 1972 a series of experiments (Skoog, Ohlsen & Sohn, 1972; 1975; Ohlsen, 1976) has been performed to elucidate the potential of perichondrial grafts to generate cartilage. In 1974 Sohn & Ohlsen demonstrated in rabbits that tracheal cartilage could be reconstructed from free perichondrial grafts. As these studies were carried out with an intact tracheal mucosa a series of experiments was conducted in rabbits, and reported in this paper, in which a tracheal section containing two cartilages and the covering mucous membrane was removed and replaced with a free perichondrial graft taken from the ear. New cartilage formed in all animals. The reconstructed portion of trachea was partly covered by ciliated cells of normal appearance, partly by low epithelium with microvilli. These latter areas were mainly within the central parts of the regenerated mucosa.The use of perichondrial grafts for tracheal reconstruction was also studied in two series of dogs. In four dogs a tracheal section, consisting of two com...

The Early Development of Articular Cartilage After Perichondrial Grafting

In an experimental series of 39 rabbits the articular cartilage of the femur condyles was resected and the defect covered by a perichondrial graft from rib cartilage. The graft was fixed to the bony surface by using Tisseal (Immuno AG) and the joint was immobilized for two weeks. Beginning 24 hours postoperatively the neochondrogenesis from the perichondrial graft was analyzed histologically, sacrificing the rabbits with 48 hours interval. The fibrin glue acted as a visible border line between the bony surface and the graft. No vascular proliferations penetrated the fibrin glue, indicating that the perichondrial graft must be nourished by the synovial fluid only. The neochondrogenesis was found to occur in the median and fibrous layer of the graft.

Reconstruction of articular cartilage using autologous perichondrial grafts. A preliminary report.

In a pilot study of grown-up rabbits perichondrium from the ear was grafted to the joint surface of cavitas glenoidalis from which the normal articular cartilage had been resected. in all cases regeneration of new cartilage occurred. Five clinical cases of arthritis are reported in which, following removal of the degenerated cartilage and grafting of rib perichondrium, articular cartilage regeneration took place

CARTILAGE REGENERATION FROM PERICHONDRIUM

Animal experiments with flaps and free grafts of perichondrium have produced new cartilage. The presence of blood seems to promote the formation of new cartilage in such instances. These perichondrial grafts have been used to produce better contours of the auricular cartilage in congenital deformities, and to reconstruct missing parts of the human ear. They are also being used clinically in joint surgery in cases of traumatic arthrosis and rheumatic arthritis to obtain painless motion.

The chondrogenic potential of the perichondrium

SummaryThe chondrogenic capacity of the perichondrium was first demonstrated by Skoog, Ohlsén and Sohn in 1972. To further elucidate this finding large series of experiments have been carried out in 2-month-old rabbits. In surgically created defects in ear cartilage, 10×15 mm and 18×18 mm, a proliferation of new cartilage was seen in all cases where a perichondrial flap had been used to bridge the defect. No growth of cartilage was found in the control groups. The formation of new cartilage originated from the deep surface of the perichondrial flap, i.e. from cell layers adjacent to the cartilage before separation of the flap. The effect of hematoma as a matrix for this growth was evident. Some experiments were devised to confirm that the perichondrium is the source of the formation of new cartilage, excluding the possibility of the cartilage edges participating in the chondrogenesis.These series of experiments have demonstrated the perichondrium to be an active tissue with a remarkable potential for cartilage generation opening promising possibilities in reconstructive surgery.

The Effect of Growth Factors and Synovial Fluid on Chondrogenesis in Perichondrium

Reconstruction of cartilage with perichondrium depends on the chondrogenic property of the perichondrial fibrocytes. The present investigation concerns the conditions for the differentiation of fibrocytes into chondrocytes both in vivo and in vitro. For the in vivo studies specimens of rib and auricular perichondrium from adult rabbits were wrapped round silicon rods which were enclosed in dialysis bags. One was placed in the suprapatellar pouch of the knee joint and one was placed intraperitoneally in each rabbit. After two months the bags were extracted, the perichondrium prepared for microscopic examination, and the chondrogenesis evaluated. In vitro the perichondrium was divided into small pieces and incubated with tissue culture medium. The medium was supplemented with fetal calf serum, together with epidermal growth factor, platelet derived growth factor, synovial fluid, or with human serum albumin (control group). After three weeks the explants were prepared for microscopy. Chondrogenesis was judged by the degree of cellular enlargement, capsule formation, deposition of matrix, and activation of the outer fibrocytic layer. In vivo, good cartilage development was found in all specimens placed in the knee joint but, in those placed intraperitoneally, little if any chondrogenesis was seen. In vitro profound differentiation occurred in all cultures supplemented with epidermal growth factor and platelet derived growth factor. An equivalent differentiation was found in perichondrium that had been incubated with synovial fluid. We conclude that the differentiation of perichondrial fibrocytes is initiated in vitro by growth factors. In addition, we have shown that synovial fluid contains factors that promote and enhance the development of cartilage from perichondrium.