Comparison Of The Methods About Measuring The Alignment Of The Lower Extremity

Objectives to compare the differences of measuring the alignment of the lower extremity among eye-measurement,conimeter-measurement and Body X-ray Measuring System,and to study the accuracy,reliability and the practicability in practical using.Methods We chose 19 patients with osteoarthritis between January and September in 2007 as our researching objects,in which there were 4 male patients and 15 female patients including 14 left knees,13 right knees and 27 knees in total.We took the Computer-assisted Body X-ray Measuring System as gold standard.We invited a senior doctor and a middle-grade doctor to respectively measure the alignment of lower extremities with eye-measurement and conimeter-measurement.We took the absolute difference and error rate as researching reference index,which was worked out by comparing the eye-measurement,conimeter-measurement with the Computer-assisted Body X-ray Measuring System.We did statistical treatment with paried t-test and ANOVA,and compared the difference between eye-measurement and conimeter-measurement,and compared that in different doctor grade,varus angle and both of them.Results The mean absolute differences of eye-measurement were 4.23°±4.3°,and that of conimeter-measurement were 3.59°±2.9°,there were no statistical differences between them (p＞0.05).The error rates of both of them were all great,there were no statistical differences between them(p＞0.05).The eye-measurement deviation of middle-grade doctor was greatest with mean absolute differences 5.73°±5.28°,that of senior doctor was smaller with mean absolute differences 2.73°±2.28°,and there were significant differences between them(p＜0.01).The differences of conimeter-measurement between the senior doctor and the middle-grade doctor were not significant(p＞0.05).There were no statistical differences between eye-measurement and conimeter-measurement for senior doctor(p＞0.05),the middle-grade doctor was the same (p＞0.05).The deviation was greater when the varus angle exceeded 10°compared with that when the varus angle was smaller than 10°for both eye-measurement and conimeter-measurement,the differences were significant(p＜0.01).Whether the varus angle was larger than 10°or smaller than 10°,there were no statistical differences between eye-measurement and conimeter-measurement.The deviation was greater when the varus angle exceeded 10°compared with that when the varus angle was smaller than 10°either eye-measurement or conimeter-measurement and either senior doctor or middle-grade doctor (p＜0.05).When the varus angle was smaller than 10°,the differences of eye-measurement between the senior doctor and the middle-grade doctor were significant(p＜0.05),but When the varus angle was larger than 10°,the differences were not significant.Whether the varus angle was larger than 10°or smaller than 10°,the differences of conimeter-measurement were not significant between the senior doctor and the middle-grade doctor(p＞0.05).Whether the varus angle was larger than 10°or smaller than 10°,the differences between eye-measurement and conimeter-measurement for senior doctor were not significant(p＞0.05).Whether the varus angle was larger than 10°or smaller than 10°,the differences between eye-measurement and conimeter-measurement for middle-grade doctor were not significant(p＞0.05).The mean absolute differences of eye-measurement and conimeter-measurement were all positively correlated with the varus angle(p＜0.01),that meant the larger the varus angle was,the greater the mean absolute differences were.Conclusion Both eye-measurement and conimeter-measurement are not accurate,there is mean deviation 3°～5°.We can choose either eye-measurement or conimeter-measurement on measuring.The senior doctor has smaller deviation of eye-measurement than the middle-grade doctor,and we' d better choose senior doctor when we use eye-measurement.When the varus angle was smaller than 10°,we can measure the alignment by using either eye-measurement or conimeter-measurement,and there are deviation about 2°～3°.Especially the eye-measurement deviation of the senior doctor is smaller than 2°when the varus angle is smaller than 10°,it is the smallest deviation.When the varus angle is larger than 10°,the deviation is greater,we'd better measure the alignment of the lower extremity with the Computer-assisted Body X-ray Measuring System.