Articular Cartilage Disorders & OCD Lesions

Articular Cartilage Disorders

Articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of the body during activities such as running and jumping. Articular cartilage does not have a direct blood supply to it so has less capacity to repair itself. Once the cartilage is torn it will not heal easily and can lead to degeneration of the articular surface, leading to development of osteoarthritis.

The damage in articular cartilage can affect people of all ages. It can be damaged by trauma such as accidents, mechanical injury such as a fall, or from degenerative joint disease (osteoarthritis) occurring in older people.

Patients with articular cartilage damage experience symptoms such as joint pain, swelling, stiffness, and a decrease in range of motion of the knee. Damaged cartilage needs to be replaced with healthy cartilage and the procedure is known as cartilage replacement. It is a surgical procedure performed to replace the worn-out cartilage and is usually performed to treat patients with small areas of cartilage damage usually caused by sports or traumatic injuries. It is not indicated for those patients who have advanced arthritis of knee.

Cartilage replacement helps relieve pain, restore normal function, and can delay or prevent the onset of arthritis. The goal of cartilage replacement procedures is to stimulate growth of new hyaline cartilage. Various arthroscopic procedures involved in cartilage replacement include:

• Microfracture
• Drilling
• Abrasion Arthroplasty
• Autologous chondrocyte implantation (ACI)
• Osteochondral Autograft Transplantation

OCD lesions

Osteochondritis dessicans is a condition of loosening or detachment of a fragment of cartilage and underlying a bone in a joint. The fragment may be localized, loosely float in the joint space, or completely detach from the cartilage or bone. Exact cause for osteochondritis dessicans remains unknown and certain factors such as trauma, fractures, sprains, or injury to the joint are considered to increase the risk of developing the condition. Following the injury or trauma, the bones in the area may be deprived of blood flow leading to necrosis and finally the bone fragment may break off. This may initiate the healing process however by this time, articular cartilage will be compressed, flattened, and a subchondral cyst will be developed. All these changes in addition to increased joint pressure cause failure of healing of the joint.

Patients with osteochondritis dessicans experience symptoms such as joint pain, stiffness, restricted motion of joints, and locking at the joint.

Your physician may recommend various treatments depending on the reports of diagnostic scans, age, severity, stability of the cartilage and other factors. Goals of treatment are to relieve the symptoms and stop or impede the progression of degeneration of the joint. Conservative treatment approaches such as wait & watch approach, pain medications, and immobilization for 1-2 weeks are recommended if the condition is diagnosed at early stages and if the severity is mild. However surgery is required if the condition is diagnosed at advanced stage or if the condition is severe.

The surgical correction of osteochondritis dessicans can be done using by open technique or arthroscopic techniques. Some of the surgical procedures include drilling, bone grafting, open reduction internal fixation, osteochondral grafting, or autologous chondrocyte implantation (ACI).

• Drilling – In this method multiple small holes are drilled into the bone which allows the growth of new blood vessels in the defect area. This promotes blood flow into defect area thereby initiating the healing response and formation of new cartilage cells inside the lesion.
• Open reduction internal fixation – Open surgery is performed in cases where the defected area is difficult to reach with arthroscope. Hence an open incision may be required. In this procedure an incision is made in front of the joint to allow the surgeon to see the joint and the loose bodies are removed. Internal fixation involves fixing the fragments using internal fixators such as metal screws, pins, or wires.
• Bone grafting – It helps to fill the gap after removal of the dead or necrotic bone. In this procedure bone graft is placed on the damaged site. This procedure may be performed to repair the damaged area or replace the missing bone. Autograft (harvested from the same individual) or allograft (taken from bone bank) may be required to help in the growth of a new bone. 
  • Osteochondral grafting - The procedure involves transfer of healthy cartilage plugs from the non-weight bearing areas of the joint and transferring into the damaged areas of the joint in mosaic pattern. It allows the newly implanted bone and cartilage to grow in the defected area.  Grafts may be taken from the same individual (autograft) or from a donor or bone bank (allograft).
  • Autologous chondrocyte implantation (ACI) – In this procedure healthy cartilage cells are harvested from the non weight-bearing joint of the patient and cultured in laboratory.  The cultured cartilage tissue patch will be implanted into the defected area which also promotes the growth of new cartilage.