1. Ki Hyuk Sung, MD Department of Orthopaedic Surgery Seoul National University Bundang Hospital Rate of correction after asymmetrical physeal suppression in valgus deformity: Analysis using a Linear mixed model application

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 Coronal angular deformity of the lower limb is a common finding in growing children Permanent (irreversible) hemiepiphysiodesis Temporary (reversible) hemiepiphysiodesis using staples, percutaneous screws, or a tension band plate (eight-plate)

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

6. Introduction Measuring the rate of correction is necessary to predict the time to end point The rate of angular correction has been calculated simply by averaging. Other factors (age, surgical method, direction of deformity, etiology, physis) must be considered while estimating the rate of correction

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 Introduction A linear mixed model (LMM) is useful in settings where multiple correlated measurements are made on the same statistical units LMM consists of fixed effects and random effects Estimation of the correction rate by using a mixed model application may confer more practical information to clinicians

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 Purpose To estimate the rate of angular correction after asymmetrical physeal suppression To analyze the factors that influence the rate of correction by using a linear mixed model application

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 Material and methods

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 Inclusion criteria Patients with valgus angular deformity of the lower limb who underwent asymmetrical physeal suppression A minimum follow-up of 3 months

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 Exclusion criteria Patients who visited our hospital less than two times Patients who had inadequate preoperative or postoperative radiographs available for review Patients who underwent any other bony procedures such as an osteotomy

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 Radiographic measurements

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 Building a linear mixed model Three groups Distal femoral, proximal tibial, and distal tibial The rate of angular correction was adjusted by multiple factors by using LMM Age, gender, and surgical method as the fixed effects Each subject as the random effect

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 Individual pattern of correction rate

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

16. Building a linear mixed model The estimates were fitted using the restricted maximum likelihood estimation (REML) method The final model Age and surgical method specific rate Sex and surgical method specific intercept

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 Statistical Methods Univariate analysis LMM was used to model the correction rates and assess covariate effects. Multivariate analysis For the final model to examine the significantly contributing factor to the rate of valgus deformity correction R (Version 2.13.1) using nlme package

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 Results

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 Patients’Demographics Physis treated Distal femur Proximal tibia Distal tibia Total No. of physes727033175 No. of measurements276305128709 Gender (Male/ Female)43/2938/3226/7107/68 Limb (Left/ Right)35/3736/3415/1886/89 Age at surgery(years, mean±SD)12.0±2.311.7±3.111.6±2.611.8±2.7 Surgical method Staple/Screw/Permanent24/44/420/47/30/28/544/119/12 Anatomical angle at initial(°, mean±SD)76.1±4.585.0±5.077.9±5.180.0±6.3 Anatomical angel at final(°, mean±SD)83.4±5.490.2±6.587.3±8.286.9±7.1 Mean amount of correction(°, mean±SD)7.3±6.05.2±4.89.4±7.46.8±6.0

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 Univariate analysis of the correction rate for distal femur FactorCoding Rate of correction (°/month) 95% Confidence interval p-value SexMale (referent)0.550.41 to 0.68<0.001* Female0.750.54 to 0.970.062 MethodStaple (referent)0.640.46 to 0.82<0.001* Screw0.640.42 to 0.870.968 Permanent0.25-0.24 to 0.740.124 AgeF<12/M<14 (referent)0.710.59 to 0.84<0.001* F≥12/M≥140.390.17 to 0.610.006*

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 Univariate analysis of the correction rate for proximal tibia FactorCoding Rate of correction (°/month) 95% Confidence interval p-value SexMale (referent)0.360.25 to 0.47<0.001* Female0.370.20 to 0.530.941 MethodStaple (referent)0.260.11 to 0.410.001* Screw0.420.24 to 0.600.085 Permanent0.28-0.12 to 0.690.909 AgeF<12/M<14 (referent)0.400.30 to 0.51<0.001* F≥12/M≥140.290.12 to 0.460.205

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 Univariate analysis of the correction rate for distal tibia FactorCoding Rate of correction (°/month) 95% Confidence interval p-value SexMale (referent)0.520.39 to 0.64<0.001* Female0.390.15 to 0.620.270 MethodScrew (referent)0.430.32 to 0.55<0.001* Permanent0.630.39 to 0.860.101 AgeF<12/M<14 (referent)0.480.36 to 0.60<0.001* F≥12/M≥140.480.18 to 0.760.947

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 Multivariate analysis of the correction rate for distal femur FactorCoding Rate of correction (°/month) 95% Confidence interval p-value BaselineStaple, F<12/M<140.790.60 to 0.97<0.001* AgeF≥12/M≥140.510.27 to 0.750.025* MethodScrew0.660.43 to 0.830.241 Permanent0.580.06 to 1.110.441 * The difference in the rate of correction between the younger children and the older children is significant.

24. 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 Multivariate analysis of the correction rate for proximal tibia FactorCoding Rate of correction (°/month) 95% Confidence interval p-value BaselineStaple, F<12/M<140.290.14 to 0.44<0.001* AgeF≥12/M≥140.14-0.04 to 0.320.098 MethodScrew0.480.29 to 0.670.046* Permanent0.38-0.03 to 0.790.660 * The difference in the rate of correction between the younger children and the older children is significant.

25. 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 Multivariate analysis of the correction rate for distal tibia FactorCoding Rate of correction (°/month) 95% Confidence interval p-value BaselineStaple, F<12/M<140.440.33 to 0.55<0.001* AgeF≥12/M≥140.350.07 to 0.640.552 MethodPermanent0.680.44 to 0.920.057 * The difference in the rate of correction according to the age and the method is not significant.

26. 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

27. Conclusion Asymmetrical physeal suppression with staples, percutaneous transphyseal screws, and permanent method all are effective methods for treating valgus deformity in growing children.

28. 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 Conclusion When we treat valgus deformity in growing children, we should take into consideration the fact that the rate of correction at the distal femur is lower in older children.

29. 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