LARGE OSTEOCHONDRAL DEFECTS OF THE FEMORAL CONDYLE -THE MEGA OATS TECHNIQUE

Abstract

Large osteochondral defects are difficult to treat, but several treatment options are available. The posterior condyle transfer salvage technique described by Wagner in 1964 and Imhoff in 1990 has been developed further and is now used for coverage of large osteochondral defects in the load-bearing zone. The new technique is called MEGA-OATS.

From July 1999, 25 patients of mean age 33.3 years (17 to 60) were treated with MEGA-OATS. Thirteen patients additionally underwent high tibial osteotomy and two bone grafting, using bone harvested from the proximal tibia. The mean follow up was 17.8 months. The technique calls for excision of the posterior femoral condyle which is placed in a specially designed work station. A MEGA-OATS cylinder of diameter 20 mm to 35 mm is prepared and, using the press-fit technique, grafted into the prepared defect zone. The Lysholm score increased postoperatively from 66.33 (49 to 71) to 87.8 (72 to 97). Three months postoperatively control MRI showed incorporation of all cylinders. Between six and 12 weeks postoperatively patients attained a full range of motion and became fully weight-bearing. To date one superficial infection resolving on oral antibiotics and two cases of arthrofibrosis four months postoperatively that required arthroscopic release were seen. No postoperative meniscal lesions of the posterior horn have been observed.

MEGA-OATS achieves a congruent reconstruction of the articular surface in the load-bearing zone of the femoral condyle. We consider it a good alternative in the treatment of large osteochondral defects of the femoral condyle in young patients.