고관절 전치환술에서 하지 길이의 변화(수술전 예상 측정치와 수술후 실제 측정치 사이의 차이에 대하여) = Leg Length Changes in Total Hip Arthroplasty-Differences between preoperative prediction and postoperative measurement-

다국어 초록 (Multilingual Abstract)

We reviewed 40 cases of cementless primary total hip arthroplasty (THA) to see the leg length changes after THA and analysed the factors that could affect the discrepancies of preoperative estimation and postoperative measurement. The cases with severe preoperative leg length discrepancy such as untreated CDH were not included in our series. Inserted femoral components were CLS(Protek) or Omnifit(Osteonics) stems. All the acetabular cups were HG g (Zimmer) cups. Preoperatively the acetabular template was mounted on the film and the center of the acetabular cup was marked with pencil. Femoral template was also mounted on the femoral side and the center of the femoral head was marked. The distaoce between the two centers was a basis for preoperative estimation. Postoperatively the leg length change was measured by the change of the distance from interteardrop line to the greater trochanter tip. Leg length change estimated by preoperative templating was 5mm lengthening in average. Postoperative leg length change was 10mm lengthening in average. The discrepancies of pre and postoperative measurement were attributed to following factors. Standardization of taking the X-ray views was an important factor. Magnification, center of X-ray beam and the accurate position of the hip should be considered in taking preoperative X-rays. Templating technique was another factor. Postoperative acetabular center shifted frequently compared with preoperative estimation. Templating does not always tell accurate postoperative leg length change. To minimize the discrepancy of pre and postoperative measurement above factors should be considered in preoperative estimation.