A cartilage defect of the knee was frequently combined with varus alignment of the knee and its treatment should be focused on cartilaginous defect as well as malalignment.

If malalignment was not adequately corrected, cartilaginous defect treatment alone was not able to be successful or recurrence could be developed.

The treatment methods of cartilage defect were microfracture, augmented microfracture, chondrocyte transplantation and stem cell treatment. Each treatment method has its advantage and disadvantages.

Correction of malalignment could be done by either open or closed wedge high tibial osteotomy. Appropriate method should be selected according to the situation.

During the last 15 years over 500 cases of high tibial osteotomy with repair of cartilage defect were performed. Clinical outcome study showed

The medial open wedge high tibial osteotomy provided good survival at mid- to long-term follow-up. The old age, high-grade cartilage injury on medial and lateral compartment, under-correction of postoperative HKA angle appeared to be significant factors associated with the failure after medial open wedge high tibial osteotomy.

Comparison analysis study between showed clinical outcomes was improved regardless of whether augmentation was administered or not. However, Augmented microfracture was is more effective for cartilage regeneration than microfracture alone in medial unicompartmental OA.