Clinical Value Of Four-point Method To Measure Joint Angle Yi Wenchao*, Hu Jianping, Li Jianan, Et Al.

Objective:To study the clinical value of four-point method to measure joint angle.Subjects and methods:Twenty five subjects without knee dysfunction were studied. Every knee joint was tested on three different positions which were extension, below 90 degree flexion and above 90 degree flexion by the traditional three-point method(TP) and the new four-point method(FP). Two physical therapists measured every position twice on the same day. Use X-ray as the gold standard. FP used the greater trochanter, the lateral condyle of the femur, the head of the fibular, and the lateral mallealus as bony marks. The angle of the two lines each of which connected two bony marks on one bone was the result of FP. TP used the greater trochanter, the lateral condyle of the femur and the lateral malleolus as bony marks. The angle with the vertex of the lateral condyle of the femur was the result of TP. Analyze the data using Bland-Altman plots which can obtain the 95% limits of agreement (LOA).Results:1. Joint measurement center moved when the position changed. 2. Reliability tests showed that the 95% LOA of the inter-tester reliability was (-5.0, 2.7) with FP and (-6.5, 4.4) with TP. The 95%LOAs of the intra-tester reliability were (-3.6, 4.0) and (-4.1, 4.8) with FP, while (-5.0, 6.4) and (-6.1, 5.8) with TP.3. Validity tests showed that the 95%LOAs of the three positions aforementioned were (-3.5, 2.6), (-3.3, 3.6) and (-1.9, 5.7) accordingly with FP. And ( -6.8, 1.1), (-4.0, 7.1) and (0, 8.5) were the results with TP.Conclusion:The results of this study indicate that FP is better than TP either in reliability or in validity.