Sung-Dae Choung

Musculoskeletal Predictors of Movement Quality for the Forward Step-down Test in Asymptomatic Women

STUDY DESIGN Cross-sectional. OBJECTIVE To investigate the interrater reliability of movement-quality ratings for the forward step-down (FSD) test and to compare hip muscle strength and lower extremity joint range of motion and muscle flexibility among asymptomatic women with different levels of movement quality. BACKGROUND The interrater reliability of the FSD test has not yet been investigated. Additionally, it is not known whether differences in musculoskeletal measures exist among individuals with different levels of movement quality during the FSD test. METHODS Two physical therapists assessed movement quality during the FSD test in 26 asymptomatic women (mean ± SD age, 22.7 ± 0.9 years). Hip muscle strength and lower extremity joint range of motion and muscle flexibility were also assessed. The interrater reliability of the FSD test was estimated by using the kappa coefficient and percent agreement. Differences in musculoskeletal measures based on movement quality were assessed by independent t tests. RESULTS The kappa coefficient and percent agreement for rating the quality of movement on the FSD test were 0.80 (95% confidence interval: 0.57, 1.00) and 85%, respectively. The subjects with moderate movement quality had significantly less strength of the hip abductors, less knee flexion range of motion measured in prone (quadriceps flexibility), and less hip adduction range of motion measured in sidelying (iliotibial band/tensor fascia latae flexibility) compared to those with good movement quality. CONCLUSION There was good agreement for the rating of movement quality during the FSD test, and there were physical attributes that distinguished those with moderate from those with good quality of movement.

The relationship between length of the iliotibial band and patellar position in Asians

BACKGROUND Tightness of the iliotibial band (ITB) has been documented as a major factor in lateral patellar translation because the ITB inserts into the lateral border of the patella through the iliopatellar band. The aim of this study was to compare the patella-condyle distance (PCD) between subjects with and without ITB tightness. We also investigated the relationship between ITB length and lateral patellar translation in hip adduction. METHODS In 40 healthy volunteers, we measured the ITB length with Obers test and the PCD at two hip positions (neutral and 20° adduction) using ultrasonography. Lateral patellar translation in hip adduction was calculated by subtracting the PCD at the adduction position from the hip neutral position. RESULTS Twenty-three of the 40 subjects had ITB tightness; these subjects had a significantly laterally positioned patella at 20° adduction of the hip (p=0.044). Patients with ITB tightness also had greater lateral patellar translation in hip adduction than patients without tightness (p=0.000). The ITB length was moderately correlated with the PCD at 20° adduction of the hip (r=0.427, p=0.042) and strongly negatively correlated with lateral patellar translation (r=-0.717, p<0.000). CONCLUSIONS These findings support the hypothesis that increasing ITB tension has a significant effect on the position of the patella and therefore affects translation of the patella. However, these findings do not indicate that ITB length is the only cause of lateral patellar translation; further studies are needed to assess the relative importance of different factors that could affect patellar position.

Comparison of muscle activity of wrist extensors and kinematics of wrist joint during wrist extension in automobile assembly line workers with and without lateral epicondylitis

BACKGROUND Overuse of the extensor carpi radialis (ECR) may play a role in the development of lateral epicondylitis (LE). However, no studies have investigated the muscle activity ratio between the ECR and extensor carpi ulnaris (ECU) associated with the kinematics during wrist extension in workers with LE. OBJECTIVE We compared the ratio (ECR/ECU) of muscle activity between the ECR and ECU and the kinematics of the wrist during wrist extension between workers with and without LE. METHODS Fifteen automobile assembly line workers with LE and 15 workers without LE participated in this study. The ratio of muscle activity was measured using surface electromyography, and wrist kinematics were measured by a three-dimensional motion analysis system while the workers extended their wrists actively to the maximum range to which they did not feel uncomfortable. RESULTS Significantly greater ratios of muscle activity, ranges of radial deviation, and combined motion of radial deviation and extension (CMDE) were shown in workers with LE compared to those without LE. Also, the range of wrist extension was significantly lower in workers with LE than in those without LE. CONCLUSIONS Quantifying the ratio of muscle activity with altered kinematics of wrist extension may help researchers to understand why overuse of ECR is occurring and explain LE development in automobile assembly line workers.