Chondral resurfacing of articular cartilage defects in the knee with the microfracture technique. Surgical technique.
BACKGROUND
Microfracture is a frequently used technique for the repair of articular cartilage lesions of the knee. Despite the popularity of the technique, prospective information about the clinical results after microfracture is still limited. The purpose of our study was to identify the factors that affect the clinical outcome from this cartilage repair technique.


METHODS
Forty-eight symptomatic patients with isolated full-thickness articular cartilage defects of the femur in a stable knee were treated with the microfracture technique. Prospective evaluation of patient outcome was performed for a minimum follow-up of twenty-four months with a combination of validated outcome scores, subjective clinical rating, and cartilage-sensitive magnetic resonance imaging.


RESULTS
At the time of the latest follow-up, knee function was rated good to excellent for thirty-two patients (67%), fair for twelve patients (25%), and poor for four (8%). Significant increases in the activities of daily living scores, International Knee Documentation Committee scores, and the physical component score of the Short Form-36 were demonstrated after microfracture (p < 0.05). A lower body-mass index correlated with higher scores for the activities of daily living and SF-36 physical component, with the worst results for patients with a body-mass index of >30 kg/m(2). Significant improvement in the activities of daily living score was more frequent with a preoperative duration of symptoms of less than twelve months (p < 0.05). Magnetic resonance imaging in twenty-four knees demonstrated good repair-tissue fill in the defect in thirteen patients (54%), moderate fill in seven (29%), and poor fill in four patients (17%). The fill grade correlated with the knee function scores. All knees with good fill demonstrated improved knee function, whereas poor fill grade was associated with limited improvement and decreasing functional scores after twenty-four months.


CONCLUSIONS
Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years. The best short-term results are observed with good fill grade, low body-mass index, and a short duration of preoperative symptoms. A high body-mass index adversely affects short-term outcome, and a poor fill grade is associated with limited short-term durability.
Mithoefer
Kai
K
Harvard Vanguard Orthopaedics and Sports Medicine, Brigham and Women's Hospital, 291 Independence Drive, Chestnut Hill, MA 02467, USA. kmithoefer@partners.org
Williams
Riley J
RJ
Warren
Russell F
RF
Potter
Hollis G
HG
Spock
Christopher R
CR
Jones
Edward C
EC
Wickiewicz
Thomas L
TL
Marx
Robert G
RG
D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D015992:Body Mass Index; D002357:Cartilage Diseases / Q000473:pathology / Q000534:rehabilitation / Q000601:surgery*; D002358:Cartilage, Articular; D005260:Female; D006801:Humans; D007719:Knee Joint; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D011446:Prospective Studies; D016896:Treatment Outcome