Articular Cartilage Injuries
What are articular cartilage injuries?
Articular cartilage provides a smooth, lubricated surface for low-friction articulation. It facilitates the transmission of loads to the underlying subchondral bone. Articular cartilage has a very limited capacity to “self-repair,” or heal on its own.
Cartilage injuries are graded with the Outerbridge Arthroscopic Grading System:
- Grade 1: Softening and swelling of cartilage
- Grade 2: Superficial fissures
- Grade 3: Deep fissures, without exposed bone
- Grade 4: Erosion of cartilage down to exposed subchondral bone
Diagnosing articular cartilage injuries
A physician’s physical examination assessing gait (walking) pattern, the range of motion of the affected joint, as well as the integrity of surrounding ligaments and musculature (atrophy).
Imaging, such as MRI’s, are utilized to evaluate cartilage thickness, subchondral bone edema, cystic change in the bone, sclerosis of bone, and if healing has occurred.
Treatment strategies are determined by the size of the cartilage (chondral) injury (lesion). Smaller lesions are managed with chondroplasty and/or microfracture. Whereas larger cartilage lesions are managed with osteochondral allo and autografts.
The purpose of Microfracture is to spark a healing response through clot formation and undifferentiated mesenchymal cells yielding a “fibrocartilage” repair.
Osteochondral autograft transfers (OAT) is a technique where the surgeon harvests viable, intact cartilage in the form of a bone plug from the patient (in a less valuable portion of the joint). Osteochondral allograft instead utilizes cadaver tissue that has been donated.