Osteochondral Scaffold: A Valid Treatment for Knee Osteochondritis Dissecans

In this study, orthopedic surgeons from Italy explore the use of a minimally invasive, one-step osteochondral scaffold to repair damage to the surface of the knee joint. The level of evidence is low (rated four on a scale from one-to-four) because it is a case series. But the information about results is still valuable when a new type of treatment is introduced.

The condition being treated is known as osteochondritis dissecans or OCD. This is an acquired injury from repetitive microtrauma. A lack of blood supply to the damaged area causes separation of the first two layers of the knee joint: the cartilage that lines the joint (articular cartilage) and the subchondral bone (bone just under the cartilage).

The end-result is a hole (referred to as a “lesion” or “defect”) in the knee joint cartilage that goes down to the bone. The defect is on the bottom of the femur (thigh bone) where the femur comes in contact with the tibia (lower leg bone). Instability of the articular cartilage causes pain, swelling, and loss of knee motion and knee function. Left untreated, uneven contact of the joint eventually causes further degeneration of the joint and arthritis.

The condition affects active teenagers and young adults most often. The patients in this study ranged in ages from 18 to 33. The most effective treatment (especially for large lesions) is surgical with a wide variety of procedures currently in use. The goal of surgery is to restore the joint surface to as normal as possible (anatomically).

Placing collagen tissue (the basic building block of cartilage and bone) into the defect is one of the techniques under investigation. In this study, a three-layer scaffold made of type I collagen fibers was placed in the defect. The surgical procedure involved removing the damaged bone, placing aluminum foil inside the hole to form a template, and then implanting the hole with the exact size of collagen graft. An on-line video is available for anyone who would like to see the procedure.

The idea was to stimulate the body to fill in the scaffold as part of the natural healing process. Did it work? Let’s look at the results two years later. Outcome measures used included: patient symptoms, knee range-of-motion, status of knee ligamentous stability, and return-to-sport. MRIs were also taken to assess the actual changes at the joint. Patient symptoms and function were compared against the MRI findings.

All measures of function improved for each patient over the two-year period. In fact, continued improvements were observed between year one and year two. The MRI showed complete filling of the defect in three-fourths of the patients by the end of the first year. There was complete integration of the graft by the end of the second year. But the subchondral bone was never fully restored and changes such as edema, cysts, and sclerosis were seen in two-thirds of the patients.

Despite what might seem like a lack of complete healing response with a return to normal joint integrity, the majority of patients had no symptoms and were able to function fully. Not only that, but the size of lesion was not an issue. Even the largest defects responded well to this treatment. A few patients (three) had some minor reactions to the treatment with knee swelling and stiffness but there were no failed procedures among the group.

The authors concluded that the use of collagen-hydroxyapatite osteochondral scaffold can be beneficial to patients with all sizes of lesions from knee osteochondritis dissecans (OCD). With the typical poor prognosis of untreated OCD, finding a successful treatment with minimal adverse effects is exciting news. This procedure has the added benefits of being a simplified, one-step, and minimally invasive surgical approach.