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Validity and Reliability of measuring femoral anteversion and neck-shaft angle in patients with cerebral palsy Seoul National University Bundang Hospital Seoul National University Children’s Hospital * Introduction Increased femoral anteversion and coxa valga are common deformities associated with intoeing gait and unstable hips in CP, which need surgical correction Physical examination and neck shaft angle measured on hip radiographs are primary tools evaluating femoral anteversion and coxa valga Introduction Physical examinations measuring femoral anteversion include Trochanteric prominence angle test (TPAT) Hip internal rotation (IR) Hip external rotation (ER) CT measurement is accurate, but expensive and involves radiation exposure Purpose of Study To assess the validity and reliability of physical examinations measuring femoral anteversion and neck shaft angle measured on hip AP radiographs Concurrent validity Intra- and interobserver reliability Materials and methods Prospective study approved by IRB 36 consecutive patients with CP scheduled for SEMLS Mean age 11.0 years (SD 1.3) M : F = 26 : 10 6 hemiplegia, 25 diplegia, and 5 quadriplegia GMFCS I / II / III / IV / V 5 / 11 / 11 / 7 / 2 Exclusion Previous Op, trauma, infection, etc. TPAT Hip IR Hip ER NSA on X ray Femoral AV on CT Standard method for concurrent validity of P/E NSA on CT Standard method for concurrent validity of NSA on X-ray Validity Physical exam measuring femoral AV Correlation with femoral anteversion measured on 2D CT NSA measured on X ray Correlation with NSA measured on 3D MPR CT image Reliability Interobserver reliability of physical exam using three orthopaedic surgeons on a single day Intra- and interobserver reliability of NSA on X- ray Repeated measurements with an interval of 3 wks Statistics Validity Reliability Pearson’s correlation coefficients Intraclass correlation coefficients (ICCs) 2 way random effects, single measurement & absolute agreement Multiple regression test To predict the accurate femoral anteversion (CT) from physical exam Results Summary of Measurements Examiation Mean (deg) SD (deg) Range (deg) TPAT 40 17 -20 to 70 Hip IR 60 17 10 to 85 Hip ER 38 14 10 to 70 Femoral AT on CT 36 18 -26 to 73 NSA on X ray 142 10 119 to 169 NSA on CT 139 8 118 to 162 Concurrent Validity of Physical exam and NSA on X ray Examinations R value p-value TPAT 0.862 <0.001 Hip IR 0.787 <0.001 Hip ER -0.480 <0.001 NSA on X ray 0.892 <0.001 Interobserver Reliability of Physical exam Examination ICCs 95% CI TPAT 0.809 0.695 to 0.890 Hip IR 0.889 0.817 to 0.937 Hip ER 0.530 0.338 to 0.702 Intra- and interobserver reliability of NSA on X ray Reliability ICCs 95% CI 1st examiner 0.973 0.947 to 0.986 2nd examiner 0.946 0.878 to 0.974 3rd examiner 0.929 0.694 to 0.974 1st session 0.937 0.825 to 0.973 2nd session 0.869 0.541 to 0.951 0.912 0.806 to 0.958 Intraobserver Interobserver Overall Femoval AV on CT = 0.92 x TPAT - 3.2 (R2=0.829) Conclusions TPAT and NSA on X ray showed clinically relevant validity and reliability compared with CT measurement CT examination evaluating proximal femoral geometry could be replaced by physical examination and X ray in patients with CP, avoiding unnecessary radiation exposure This study has been published in JBJS-Am. Thank you !