Articular cartilage repair and tissue engineering Flashcards
What is normally the cause of a focal lesion?
Trauma (usually in the young) Repetitive impact (i.e. repetitive strain, misalignment, wear and tear)
What are the types of focal lesion?
Chondral defect
Osteochondral defect?
What is a chondral defect?
Lesion entirely within cartilage, doesn’t penetrate bone
Doesn’t heal spontaneously due to no blood supple i.e. not stem cell access
What is an osteochondral defect?
Penetrate to vascularised bone
May heal spontaneously since chondroprogenitor (mesenchymal cell that differentiates into an osteoblast) cells can invade from blood - however usually form fibrocartilage
What are the different classifications of defect?
grade I: fissures extending into superficial cartilage
grade II: fibrillation/multiple fissures extending to half depth of cartilage
Grade III: fissures extending to full depth of cartilage
Grade IV: complete catilage loss and subchondral bone exposed
How would you treat a large defect?
Total joint arthroplasty, i.e. replacement
Both articular surfaces replaced with prostheses
How do you treat small intermediate defects?
Debridement Microfracture Osteotomy Osteochondral grafting Autologous chondrocyte implantation
What is debridement?
Frayed edges of tears removed
- reduces friction and inflammation
Pain relief but relapse likely within 5 years as no repair will occur
What is microfracture?
Punctures made into subchondral bone
- allow stem cell access for repair
May stimulate repair but fibrocartilage usually forms which is not as load resistant as hyaline cartilage
What are the negatives of osteochondral grafting?
Difficult to get the correct thickness when doing the repair
What is osteochondral grafting?
Graft of cartilage taken from patient or cadaver and grafted over defect using fibrin glue
What is autologous chondrocyte implantation?
Chondrocytes grown in lab from biopsy from patient and place in defect using a periosteal flap
Repairs lesions and good results, but only suitable for small lesions
What are the negatives of osteostomy?
Highly invasive and no cartilage repair
What is an osteotomy and what are the positives?
Wedge of bone removed, to remove deformity and improve biomechanics. This reestablises normal loading.
What is the downside to autologous chondrocyte implantation?
Only suitable for small lesions
