Microfracture significantly improved knee function in patients with isolated full-thickness cartilage defects of the femur, Kai Mithoefer, M.D., reported at the annual meeting of the American Academy of Orthopaedic Surgeons.
His prospective evaluation of the common technique, which involves clearing out defective cartilage and creating a series of holes in the subchondral bone to stimulate growth of fibrocartilaginous repair tissue, showed that best results were obtained in patients who had good repair tissue fill, low BMI, and symptom duration less than 12 months.
In the study, 48 patients were evaluated, with a minimum 2-year follow-up, using a combination of validated outcomes scores—including the SF-36 and Activities of Daily Living scores—cartilage-sensitive MRI, and a subjective rating. Most patients were male; they averaged 21 years of age.
Patients with high functional scores had lower BMI and shorter preoperative symptoms, reported Dr. Mithoefer, of Massachusetts General Hospital, Cambridge.
MRI demonstrated good repair-tissue fill in the defect in 55% of patients, moderate fill in 29%, and poor fill in 17%. Patients with good fill grade “had significantly more improvement in all the scores than patients with moderate fill grade,” he said. Poor fill grade was associated with limited improvement and decreasing functional scores after 24 months. Patients with also had higher BMI and a longer duration of symptoms, he reported.