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Child Orthopedics
Spine - Cervical
Spine - Lumbar
Spine - Thoracic

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Our 17-year-old son is going to have surgery for a condition called osteochondritis dissecans of his knee. Despite all efforts, he just hasn't healed. Next year he will go off to college. Would it be better for him to have screws put in that are biodegradable? We're just not sure how or when he'll be able to have the metal screws taken out again.

Osteochondritis dissecans (OCD) is a disorder of the bone with a fracture in the joint surface that doesn't heal naturally. The problem can affect the elbow, ankle, or knee. OCD of the knee mostly affects the rounded end of the lower femur (thigh bone). This area is called the femoral condyle of the knee. Like most joint surfaces, the femoral condyles are covered in articular cartilage. Articular cartilage is a smooth, rubbery covering that allows the bones of a joint to slide smoothly against one another. The problem occurs where the cartilage of the knee attaches to the bone underneath. The area of bone just under the cartilage surface is injured, leading to damage of the blood vessels to the bone. Without blood flow, the area of damaged bone actually dies. This area of dead bone can be seen on an X-ray and is sometimes referred to as the osteochondritis lesion. The lesions usually occur in the part of the joint that holds most of the body's weight. This means that the problem area is under constant stress and doesn't get time to heal. It also means that the lesions cause pain and problems when walking and putting weight on the knee. It is more common for the lesions to occur on the medial (inside) femoral condyle, because the inside of the knee bears more weight. At age 17, your son has probably reached skeletal maturity so falls in the adult treatment category. In the skeletally mature adult, the best treatment remains unclear. Surgeons try to preserve the bone fragment(s) by reattaching them to the bone with screws, pins, nails, darts or some combination of these fixation devices. Newer bioabsorbable fixation is now available for this problem. But the results of using this type of fixation that gets absorbed by the body (and doesn't have to be removed) are unknown. In a recent report from a study at the Mayo Clinic, there were many problems using bioabsorbable fixation devices and a low healing rate. In two-thirds of the group, the fragment adhered to the bone in what is referred to as fragment union. One-third of the group ended up having the loose piece taken out in a separate surgery later. Bioabsorbable nails (with no threads like the screws) had a tendency to break or back out. When that happened, the patient had a new hole in the joint surface of the femur and sometimes another one on the tibial (lower leg bone) side. The authors concluded that in all honesty they couldn't recommend bioabsorbable fixation for OCD lesions in skeletally mature adults. This treatment approach clearly is not superior to others such as using metal fixation or drilling tiny holes into the joint surface to stimulate healing, a procedure called microfracture. Your surgeon is the best one to advise you in this decision. Patient factors such as severity of the lesion(s), skeletal maturity of your son, future living location, and so on all factor into the final treatment choice.


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