Use of a screw and plate system for a transtrochanteric anterior rotational osteotomy for osteonecrosis of the femoral head.

BACKGROUND

We originally used two or three large cancellous screws for a transtrochanteric rotational osteotomy for osteonecrosis. Since January 2002, a screw and plate system (K-MAX Adjustable Angle Hip Screw) has been used to obtain more rigid fixation at the site of osteotomies. We investigated the clinical and radiological results of a transtrochanteric anterior rotational osteotomy.

METHODS

Between January 2000 and December 2001, a transtrochanteric anterior rotational osteotomy with large cancellous screws was performed in 25 hips of 22 patients, and between January 2002 and March 2005, the K-MAX Adjustable Angle Hip Screw was used in 44 hips of 40 patients for treatment of osteonecrosis of the femoral head. Japanese Orthopaedic Association (JOA) score, postoperative management, and radiographic appearances were investigated.

RESULTS

The mean preoperative JOA score was 60.8 +/- 12.1 points in the large cancellous screw group and 61.5 +/- 14.4 points in the K-MAX Adjustable Angle Hip Screw group. This improved to 86.1 +/- 13.3 points in the large cancellous screw group and 88.7 +/- 6.6 points in the K-MAX Adjustable Angle Hip Screw group at the final follow-up. Intentional varus angulations were obtained in 15 of 25 hips in the large cancellous screw group and in 36 of 44 hips in the K-MAX Adjustable Angle Hip Screw group. Altogether, 23 of 25 (92.0%) cases with large cancellous screws started partial weight-bearing 7 weeks after the operation, and 43 of 44 (97.7%) cases with the K-MAX Adjustable Angle Hip Screw started 5 weeks after the operation.

CONCLUSIONS

The K-MAX Adjustable Angle Hip Screw produced clinical results similar to those with the large cancellous screws. In addition, partial weight-bearing could be started 2 weeks earlier after a transtrochanteric anterior rotational osteotomy with the K-MAX Adjustable Angle Hip Screw.