1. Ki Hyuk Sung, MD Relationship between isometric muscle strength, gait parameters, and gross motor function Seoul National University Bundang Hospital

2. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Introduction Muscle weakness is a common impairment in patients with cerebral palsy Lower limb muscle strength is reduced by 6%- 59% compared with peers with typical development

3. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Introduction Muscle strength had a significant association with gross motor function Muscle strengthening exercise could result in functional improvements Recent studies showed no improvement of functional activity after muscle strengthening training

4. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Introduction No single study which investigates the relationship between muscle strength and gross motor function, gait kinematics, and gait kinetics in patients with CP

5. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Purpose of the study To the correlation between isometric muscle strength and gross motor function, gait kinematics and kinetics in ambulatory patients with spastic CP

6. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Materials and Methods Prospective design Inclusion –consecutive ambulatory patients with spastic CP –patients who planned for single event multilevel surgery including DHL –preoperative 3D gait analysis and gross motor function measure (GMFM) scoring

7. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Measuring isometric muscle strength Handheld dynamometer

8. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Measuring isometric muscle strength Hip flexor muscle

9. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Measuring isometric muscle strength Hip extensor muscle

10. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Measuring isometric muscle strength Knee flexor muscle

11. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Measuring isometric muscle strength Knee extensor muscle

12. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Gross motor function measure (GMFM) –88 items within five dimension –Dimension D(standing) and E(walking, running, jumping) scoring 3D gait analysis –Kinematic, kinetic and temporal parameters

13. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Reliability of strength measurement Intra-session reliability, 3 trial ICC (intraclass correlation coefficient) & 95% confidence interval

14. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Statistical analysis Correlation between peak isometric strength and GMFM, gait kinematics and gait kinetics –Pearson’s correlation coefficient Difference in peak isometric muscle strength according to GMFCS level –One-way analysis of variance (ANOVA)

15. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Results

16. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Demographics, GMFM, and peak isometric strength of patients Muscle groupPeak isometric strength Age (year)11.5±7.7 (range 5.3 -30.5)Hip flexor (N)8.71±6.53 Gender (M / F)13 / 12Hip flexor (N/kg)0.26±0.12 Type (hemi/di/quadri)7/ 17/ 1Hip extensor (N)15.46±12.30 GMFCS level (I/ II/ III)7/ 13/ 5Hip extensor (N/kg)0.51±0.36 Height (cm)130.6±20.9Knee flexor (N)6.60±5.47 Weight (kg)33.9±18.6Knee flexor (N/kg)0.21±0.14 GMFM-D (%)85.1±33.9Knee extensor (N)10.26±5.30 GMFM-E (%)73.9±20.7Knee extensor (N/kg)0.34±0.20

17. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Intra-session reliability of measurements of peak isometric muscle strength Muscle groupsICC95% CI Hip flexor0.9750.951 to 0.988 Hip extensor0.9730.948 to 0.987 Knee flexor0.9840.970 to 0.992 Knee extensor0.9730.949 to 0.987 ICC, intraclass correlation coefficient; CI, confidence interval

18. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Correlations between peak isometric muscle strength and GMFM Muscle groups GMFM-DGMFM-E rprp Hip flexor0.0140.9500.2250.290 Hip extensor-0.2660.2090.0420.847 Knee flexor-0.0570.7850.1830.381 Knee extensor-0.2550.219-0.1150.584 GMFM, gross motor function measure

19. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Peak isometric muscle strength according to GMFCS levels Muscle groupsGMFCS IGMFCS IIGMFCS IIIp Hip flexor (N/kg)0.27±0.090.29±0.150.19±0.060.338 Hip extensor (N/kg)0.53±0.270.59±0.410.21±0.110.172 Knee flexor (N/kg)0.24±0.140.22±0.160.12±0.100.352 Knee extensor (N/kg)0.36±0.210.36±0.220.24±0.060.478 Data are presented as mean ± SD. GMFCS, gross motor function classification system

20. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Correlations between peak isometric muscle strength and gait kinematics Parameters Hip flexorHip extensorKnee flexorKnee extensor rprprprp Stride length-0.0770.719-0.0800.7110.1200.568-0.0290.891 Cadence-0.1100.6100.0000.999-0.0800.704-0.0220.919 Walking speed-0.1140.596-0.0920.669-0.0160.939-0.1600.444 Maximum pelvic tilt -0.1780.405-0.5520.005-0.1030.626-0.3770.063 Mean pelvic tilt-0.2020.344-0.5810.003-0.1380.511-0.4200.037 Maximum pelvic obliquity -0.2180.306-0.4630.023-0.2170.297-0.4330.031 Mean pelvic obliquity 0.0300.890-0.2090.328-0.0230.912-0.2760.181 Minimum hip flexion -0.0990.646-0.3140.135-0.0040.986-0.0590.778 Maximum hip flexion in stance -0.2060.334-0.3750.071-0.0290.889-0.1060.615 Maximum hip flexion in swing -0.3520.092-0.5430.006-0.2410.247-0.2630.203 Knee flexion at initial contact 0.0260.9040.3210.1270.1260.5490.4960.012 Minimum knee flexion in stance 0.1010.6390.3950.0560.1190.5720.4490.025 Peak knee flexion in swing -0.3690.076-0.2230.295-0.3060.137-0.1320.528 Knee flexion at terminal swing 0.0320.8800.3000.1540.1160.5790.4680.018

21. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Correlations between peak isometric muscle strength and gait kinetics Kinetic parameters Hip flexorHip extensorKnee flexorKnee extensor rprprprp Hip Flexion/Extension Moment Peak Extensor in early stance 0.1620.451-0.1250.5590.1600.440-0.1880.367 Peak Flexor in stance -0.1010.6390.0150.946-0.0410.8460.1170.578 Peak Extensor in swing 0.0080.970-0.2120.321-0.0730.728-0.3340.102 Hip Flexion/Extension Power Peak generation in early stance 0.0980.648-0.1440.5010.1350.521-0.1060.614 Peak absorption in mid-stance 0.2830.1800.2370.2650.1680.4220.2150.301 Peak generation in terminal stance -0.2360.267-0.2830.180-0.1860.374-0.2740.185 Knee Flexion/Extension Moment Peak extensor in early stance 0.1620.4500.3780.0680.2980.1480.4300.032 Peak Flexor in mid-stance 0.1790.4030.3110.1390.1440.4930.3270.111 Peak extensor in terminal stance 0.1080.6160.2970.1590.1920.3570.4160.038 Peak flexor in swing 0.1500.4850.1650.4420.1170.5770.2690.193 Knee Flexion/Extension Power Peak absorption in early stance 0.3400.1040.0670.7550.1850.3770.0150.943 Peak generation during stance 0.1540.4720.3020.1520.2860.1660.3120.130 Peak absorption in terminal stance -0.2010.346-0.1980.353-0.1400.505-0.1950.350 Peak absorption in terminal swing 0.4400.0310.4470.0290.4740.0170.4350.030

22. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Conclusions There is no correlation between muscle strength and gross motor function. However, higher muscle strength, especially extensor muscle group of hip and knee joint, stabilizes the pelvic motion and makes walking more energy-efficient in flexed knee gait.

23. SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL ◦ SEOUL NATIONAL UNIVERSITY BUNDANG HOSPITAL Thank you !