The outcome effect of shoe lift for individuals with low back pain and pronated foot due to anatomical leg length discrepancy
Date Issued
2011
Date
2011
Author(s)
Lee, Yi-Chen
Abstract
Many musculoskeletal symptoms are highly correlated with leg length discrepancy (LLD), which may be related to asymmetric loading on weight-bearing joints and malalignments of the lower extremities. Leg length adjustment has been reported effective on relieving clinical symptoms; however, its mechanism is still unclear. The purpose of this research was to explore the feasibility of measurement of leg length using a laser distance meter, to determine the effect of leg length adjustment on pain relief at low back, pronation control of the long leg, kinematic changes in the feet for people with anatomical LLD. Four study objectives were developed: 1) to examine the validity and reliability of measurement of leg length using a laser distance meter, 2) to examine the effect of leg length adjustment on pain status and daily functions, 3) to examine the effect of leg length adjustment on controlling excessive pronation of the long leg, and 4) to examine the effect of leg length adjustment on the kinetic variables of ground reaction force.
The present research was designed as a convenient sampling, prospective, quasi-experimental, and pretest/posttest design. There were 2 parts in this research: 1) validity and reliability tests of measurement of standing leg length using a laser distance meter and 2) the effect of leg length adjustment on pain relieving, foot pronation
controlling, and related kinetic changes in people with anatomical LLD. For the validity test, standing leg length was obtained through both pelvic radiography and the laser
distance meter in 10 healthy male adults. The results were analyzed using Pearson’s correlation coefficient. For the reliability test, 15 healthy adults received measurements
of standing leg length twice using a laser distance meter by the same rater on the same day. Intraclass correlation coefficient (ICC(3,3)) and standard error of measurement
(SEM) was calculated to present intrarater reliability. Another 30 adults with anatomical LLD were recruited for the second part of the research. The visual analog scale and modified Oswestry Disability Index before and 1-month after intervention were compared using the paired t test, respectively. All participants received the navicular
drop test, Foot Posture Index (FPI), quiet stance for 60s, and level walking for 6 m at pre-, immediate after, and 1-month after leg length adjustment. ANOVA with repeated
measures or Friedman test was calculated to compare the differences among 3 time points. Crosstable analysis with Fisher’s exact test was calculated for FPI. The
significant level was set at α = 0.05 while the power was at 0.8.
The main results of the present research were: 1) using the laser distance meter to measure LLD is valid (r>0.96) and reliable (ICC(3,3) >0.99 and SEM <0.2 cm), 2) the pain status and daily function significantly improved after 1-month intervention, 3) there was a significant decrease in the subtalar pronation of the long leg after 1-month
intervention but the effect size was between small and median level only, and 4) more symmetric force distribution was noted at quiet stance after intervention in the
participants with more weight on the long leg but not for those with more weight on the short leg.
These results concluded that leg length adjustment relieved back pain and improve daily function successfully but failed to alter the foot type. Although the kinetic
variables did not completely explain the effect of intervention, the initial weight bearing pattern at stance affected the results of symmetric wearing bearing pattern after intervention. The laser distance meter was an alternative tool to measure leg length, which presented an excellent validity and reliability, which is a useful clinical tool. All of the above findings give an insight that leg length adjustment can control clinical symptoms which result from anatomical LLD, but the actual mechanism is still further studied.
Subjects
leg length
pronated foot
low back pain
shoe lift
laser distance meter
Type
thesis
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