Deneysel osteokondral defekt modelinde düşük doz X ışınlamanın Hyalin kıkırdak benzeri fibrokartilaj onarım dokusunun yapısal ve mekanik özelliklerine etkisi
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Date
2006
Authors
Öncan, Tevfik
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Publisher
Uludağ Üniversitesi
Abstract
Eklem kıkırdağının iyileşme kapasitesinin kısıtlı olduğu iyi bilinmektedir. Oluşan bir travmatik defekt subkondral kemiği geçerse kemikiliğinden gelen multipotent kök hücreleri ile hyalin kıkırdak benzeri fibrokartilaj (HKBF) doku oluşarak iyileşirler. Oluşan bu iyileşme dokusu genellikle birsüre sonra dejenere olarak osteoartrite neden olur. Çalışmamızda düşük doz X ışınları kullanarak, osteokondral defektlerde oluşan bu HKBF dokunun yapısı ve mekanik özelliklerini geliştirmeyi ve böylelikle daha fazla hyalinkıkırdağa benzeyen ve daha dayanıklı bir doku oluşturmayı amaçladık.20 adet tavşanın 40 dizinin medial kondilinde osteokondral defekt oluşturuldu. Her tavşanın sadece bir dizine postoperatif 7. günden itibaren 5gün boyunca her gün 1 Gy (5 x 1.0 Gy) radyoterapi uygulandı. 4. ve 8.haftalarda beşer tane tavşan 12. haftada ise kalan 10 tavşan sakrifiye edildi.12 hafta takip edilen tavşanlardan 5 tanesinin her iki dizindeki defekt bölgesi biyomekanik olarak sıkıştırma testi ile değerlendirildi. Geri kalan 15 tavşanın(4, 8 ve 12 hafta takip edilen beşer tavşan) dizlerindeki defekt bölgesi ise;önce makroskopik olarak değerlendirildi, daha sonra da mikroskopik olarak incelendi. Çalışma ve kontrol grupları O'Driscoll skorlama sistemine göre karşılaştırıldı. Biyomekanik olarak test edilen 12 haftalık defektlerde radyo terapi uygulanan ve kontrol grubu arasında istatiksel olarak anlamlı fark bulunamadı (sırasıyla 153,20 ± 61,91 ve 161,87 ± 64,55 N/mm; p=0,686).Makroskopik olarak değerlendirildiğinde çalışma ve kontrol dizleri arasında ve farklı süreler takip edilen gruplar arasında bir fark tespit edilemedi. Histolojik olarak değerlendirildiğinde ise O'Driscoll skorlama sistemine göre aldıkları toplam puanlar açısından çalışma ve kontrol dizlerindeki defektler arasında anlamlı bir fark yoktu (p = 0.300). Sadece 4. haftada kontrol dizlerine göre çalışma grubunda daha fazla dejenerasyon kaydedildi(p<0.05). 8. ve 12. haftalarda ise bu fark kayboluyordu. Sonuç olarak; -in vivo koşullarda- düşük doz x ışınlama uygulanan HKBF onarım dokusu ile normal HKBF onarım dokusunun mekanik ve histolojik özellikleri arasında istatistiksel olarak anlamlı bir farklılık saptanmamıştır. Ancak 4. haftada çalışma grubunda daha fazla kondrosit kümelenmesi gibi yapısal değişiklikler görülmüştür. X ışınlarının istenen ve istenmeyen etkilerinin daha ayrıntılı olarak belirlenebilmesi ve akla uygun olarak kullanılabilmesi için daha kapsamlı ve uzun süreli çalışmalara ihtiyaç vardır.
It is well known that, healing capacity of articular cartilage is limited. fthe traumatic defect penetrates to the subchondral bone, hyaline cartilagelike fibrocartilage (HCLF) tissue will be formed by the multipotent stem cellsderived from bone marrow. This repair tissue eventually will degenerate andprogress to osteoarthritis. In this study, our purpose was to modify thestructure and mechanical properties of this HCLF tissue by using low-dose Xirradiation, thus, obtaining a more durable tissue that is more resembling tohyaline cartilage.The osteochondral defects were created on the medial condyles of 40knees of 20 rabbits. Beginning from 7th day postoperatively, only one knee ofeach rabbit was exposed to 1 Gy of radiotherapy for 5 days (5 x 1.0 Gy). Fiveof the rabbits sacrificed on 4th and five of them on 8th week and the rest 10rabbits on 12th week. Defects of both knees of five of the rabbits thosefollowed for 12 weeks were examined biomechanically by compression test.All of the defects on the knees of 15 rabbits (5 rabbits on each 4th, 8th and12thweeks) first evaluated macroscopically and then examined microscopically.The study and the control groups were compared according to the scoringsystem of O?Driscoll.The defects that were biomechanically tested on 12th week; there wasno statistically significant difference between radiotherapy and control groups(153,20 ± 61,91 and 161,87 ± 64,55 N/mm respectively; p=0,686). Whenexamined macroscopically; neither difference was found between the studyand the control groups nor between groups that were followed for differenttime intervals. When examined microscopically, there was no significantvdifference between the study and the control groups in respect to the totalscores got from O?Driscoll system (p=0.300).The only difference was themore degeneration recorded in study group at 4th week (p < 0.05). Thisdifference disappeared at 8th and 12th weeks.In conclusion; there is no statistically significant difference detectedbetween mechanical and histological properties of normal HCLF repairtissues and those of ones exposed to low dose X irradiation. However, somestructural alterations such as chondrocyte clustering at 4th week wereobserved. More extended and longer studies should be done for moredetailed definition of wanted and unwanted effects of X rays and for rationaluse of them.
It is well known that, healing capacity of articular cartilage is limited. fthe traumatic defect penetrates to the subchondral bone, hyaline cartilagelike fibrocartilage (HCLF) tissue will be formed by the multipotent stem cellsderived from bone marrow. This repair tissue eventually will degenerate andprogress to osteoarthritis. In this study, our purpose was to modify thestructure and mechanical properties of this HCLF tissue by using low-dose Xirradiation, thus, obtaining a more durable tissue that is more resembling tohyaline cartilage.The osteochondral defects were created on the medial condyles of 40knees of 20 rabbits. Beginning from 7th day postoperatively, only one knee ofeach rabbit was exposed to 1 Gy of radiotherapy for 5 days (5 x 1.0 Gy). Fiveof the rabbits sacrificed on 4th and five of them on 8th week and the rest 10rabbits on 12th week. Defects of both knees of five of the rabbits thosefollowed for 12 weeks were examined biomechanically by compression test.All of the defects on the knees of 15 rabbits (5 rabbits on each 4th, 8th and12thweeks) first evaluated macroscopically and then examined microscopically.The study and the control groups were compared according to the scoringsystem of O?Driscoll.The defects that were biomechanically tested on 12th week; there wasno statistically significant difference between radiotherapy and control groups(153,20 ± 61,91 and 161,87 ± 64,55 N/mm respectively; p=0,686). Whenexamined macroscopically; neither difference was found between the studyand the control groups nor between groups that were followed for differenttime intervals. When examined microscopically, there was no significantvdifference between the study and the control groups in respect to the totalscores got from O?Driscoll system (p=0.300).The only difference was themore degeneration recorded in study group at 4th week (p < 0.05). Thisdifference disappeared at 8th and 12th weeks.In conclusion; there is no statistically significant difference detectedbetween mechanical and histological properties of normal HCLF repairtissues and those of ones exposed to low dose X irradiation. However, somestructural alterations such as chondrocyte clustering at 4th week wereobserved. More extended and longer studies should be done for moredetailed definition of wanted and unwanted effects of X rays and for rationaluse of them.
Description
Keywords
Düşük doz X ışınlama, Hyalin kıkırdak benzeri fibrokartilaj, Deneysel osteokondral defekt, Low dose X irradiation, Hyaline cartilage like fibrocartilage, Experimental osteochondral defect
Citation
Öncan, T. (2006). Deneysel osteokondral defekt modelinde düşük doz X ışınlamanın Hyalin kıkırdak benzeri fibrokartilaj onarım dokusunun yapısal ve mekanik özelliklerine etkisi. Yayınlanmamış uzmanlık tezi. Uludağ Üniversitesi Tıp Fakültesi.