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A comparison of the healing potential of fibrillated cartilage versus eburnated bone in osteoarthritic knees after high tibial osteotomy: An arthroscopic study with 1-year follow-up.

PURPOSE
To determine the healing potential of fibrillated cartilage in osteoarthritic (OA) knees when the mechanical condition is corrected.


TYPE OF STUDY
Prospective study.


METHODS
Subjects were patients treated with high tibial osteotomy alone for medial-compartment OA knees. They were divided into 2 groups on the basis of the Outerbridge classification; group A consisted of 37 grade IV knees (eburnation group), and group B consisted of 36 grade III knees (fibrillation group). Twelve months after surgery, the repair of joint cartilage was evaluated for arthroscopic finding and histology.


RESULTS
Arthroscopic examination of the femoral joint surface showed that, in group A, 9 knees (24%) were grade II, 14 (38%) were grade III, and 14 (38%) were grade IV; in group B, 3 knees (9%) were grade II, 30 (91%) were grade III, and none were grade IV. On the other hand, examination of the tibial joint surface showed that, in group A, 5 knees (16%) were grade II, 15 (47%) were grade III, and 12 (37%) were grade IV; in group B, 3 knees (9%) were grade II, 28 (80%) were grade III, and 5 (11%) were grade IV. Thus, the incidence of cartilage repair was significantly higher in group A than in group B on both femoral (P <.01) and tibial (P <.05) joint surface. Histologic findings showed most of the nonrepaired joint surface of fibrillated cartilage appeared to be hyaline cartilage, but repair tissues of eburnated bone were mainly fibrocartilage.


CONCLUSIONS
The repair of fibrillated cartilage was not promoted, but its degeneration was prevented by correction of the mechanical status. Our results show that fibrillated cartilage in OA knees has little potential for repair even though the mechanical status is corrected.