Comparison of two methods for reducing length discrepancy in hip hemiarthroplasty / 中华老年医学杂志

ABSTRACT

Objective:To compare the accuracy of two methods in reducing leg length discrepancy(LLD)during hip hemiarthroplasty.Methods:We retrospectively analyzed 89 patients of hip hemiarthroplasty who suffered from femoral neck fracture.There were 47 patients in the new method group(NM), and 42 patients in the traditional method group(traditional method, TM)which comparing the position of the greater trochanter tip and the center of the femoral head.In the NM group, the distance from the center of femoral head to the lesser trochanter(L)and the diameter of femoral head(D)of the healthy side hip were measured on preoperative anteroposterior pelvic X-ray film, and the ratio(R)of D to L was calculated.During operation, the diameter of the femoral head(d)was measured with a caliper, and the distance should be obtained from the center of the femoral head prosthesis to the lesser trochanter according to the ratio R of the healthy side.The difference of postoperative LLD between the two groups and the incidences of |LLD| in each range were compared.Results:In the NM group, the maximum LLD was 11.10 mm and the minimum LLD was -4.0 mm, with an average of(4.4±3.2)mm, 80.9%(38/47)| LLD | < 6 mm, 93.6%(44/47)| LLD | < 10 mm, 6.4%(3/47)| LLD | ≥ 10 mm.In the TM group, the maximum LLD was 13.2 mm and the minimum LLD was -8.3 mm, with an average of (6.2±5.1)mm, 42.9%(18/42)|LLD|<6 mm, 69.0%(29/42)|LLD| <10 mm, 31.0%(13/42)|LLD|≥10mm.The differences of patients of the mean postoperative LLD and the incidences of |LLD| in each range between two the groups were statistically significant( t=-2.036、 χ2=14.629, P=0.046、0.001). Conclusions:The new method is simple, convenient, more accurate and can obtain a more satisfactory LLD compared with the traditional method which refers to the relative position of the great trochanter tip and the center of the femoral head.