LEG LENGTH DISCREPANCY;

The reliability of tape measure method

Abstract

Objective: Leg length discrepancy (LLD) has been deemed one of the causative factors for back, sacroiliac conditions and
hip pathologies in patients. Increased LLD can exacerbate musculoskeletal impairments in patients that would require the clinician to
reflect on the appropriate treatment strategies. The objective of the study was to measure the reliability of “Tape Measure Method” in Leg
length discrepancy. Methodology: This is a hospital based study. The procedures for obtaining leg length measures in the study were
similar to those described by Magee DJ (Orthopedic physical assessment. 5thed).The primary investigator briefly reviewed the
procedures for measuring the leg length with the subjects. Only the subject’s right side was measured for the study. The subject’s weight
and height were measured using a standard scale and recorded. The first rater palpated the prominent aspect of the ASIS. The rater then
guided the string to the prominent aspect of the MM. The rater repeated this procedure three times for each subject. After the first rater
obtained three strings that correspond to the leg length, the second rater repeated the three measurements using the same procedure.
After all cuts of strings were obtained each rater measured the lengths of his three strings with a standard tape measure and was recorded
on a separate data sheet. Each rater was blinded to the other measures. Results: Means and standard deviation for each subject’s age,
height, weight and BMI were measured. Mean standard deviation and 95% Confidence interval (95% CI) for leg length measurements for
both raters are provided in Table 2. According to the results derived from data there were no significant differences in leg length measures
between Rater 1 and Rater 2 (t-value = - 0.000; df = 58; p-value = .9981). The ICC (3, 3) for Rater 1 was .999, (95% CI = .998 to .999).
This value indicates almost perfect agreement between the measures for Rater 1. The ICC (3, 3) for Rater 2 was .979 (95% CI = .962 to
.990). These findings are indicative of almost perfect agreement between the measures. The ICC (2, 2) between Rater 1 and Rater 2 was
.987 (95% CI = .972 to .994). A Bland-Altman plot identifies any bias between the two raters. The bias line is almost on zero, indicating no
bias between the two raters. It can be concluded that any observed bias was not clinically important. Conclusions and Discussion: It was
concluded measuring leg length using the tape measure was simple and highly reliable. There were several limitations that may have
influence overall results of the study.