<p> SUPPLIMENTERY TABLES A. Univariate Linear Regression Analysis for Hip Pain 1 year 2 years Variable P B P B (95% P CI) Age 0.161 0 0.470 0.10 (- 0.051 0.00, 0.20) Female 0.009 0 0.593 1.04 (- 0.287 0.88, 2.96) BMI 0.992 - 0.407 0.00 (- 0.959 0.16, 0.17) ASA Score 0.705 - 0.567 -0.88 (- 0.294 2.52, 0.77) Pre Hip Pain Score - 0 0.128 0.26 0.024 (0.03, 0.48) Pre Hip Function Score <0.001 0 0.180 -0.02 (- 0.768 0.12, 0.09) Pre SF12 PCS <0.001 0 0.003 0.22 0.016 (0.04, 0.40) Pre SF12 MCS 0.003 0 0.009 0.12 0.011 (0.03, 0.20) Surgical Approach - 0 0.636 1.79 (- 0.066 0.12, 3.71) Cementation - - 0.988 1.23 (- 0.168 0.52, 2.97) Femoral Head Size - - 0.312 -0.34 (- 0.720 2.17, 1.50) K-L 0.327 1 0.103 1.48 (- 0.116 0.37, 3.34) Modified K-L 0.730 0 0.057 0.89 (- 0.064 0.05, 1.84) Joint Space Narrowing 0.241 0 0.165 1.35 (- 0.062 0.07, 2.78) Pattern (none=0/hypertrophic=1/atrophic=2) 0.806 0 0.192 -0.41 (- 0.562 1.79, 0.98) Supero-lateral=1/Medial-concentric=2 0.734 1 0.041 1.48 (- 0.126 0.42, 3.39) Protrusio 0.067 - 0.870 0.93 (- 0.614 2.69, 4.55) Chondrocalcinosis 0.887 - 0.116 0.03 (- 0.989 3.97, 4.03) Bone Destruction 0.534 1 0.045 1.04 (- 0.123 0.28, 2.37) Osteophytosis 0.144 0 0.523 -0.37 (- 0.570 1.63, 0.90) (B) Beta coefficient – Represents the magnitude of change in pain score</p><p>B. Univariate Linear Regression Analyses for Hip Function Pre-op 1 year 2 years Variable B (95% CI) P B (95% CI) P B (95% P CI) Age -0.20 (-0.30, -0.11) <0.001 -0.21 (-0.33, -0.10) <0.001 -0.28 (- <0.001 0.41, -0.15) Female -3.74 (-5.55, -1.93) <0.001 -1.75 (-3.99, 0.49) 0.126 -3.32 (- 0.009 5.81, -0.84) BMI -0.22 (-0.38, -0.06) 0.008 -0.53 (-0.72, -0.34) <0.001 -0.47 (- <0.001 0.68, -0.25) ASA Score -3.69 (-5.24, -2.14) <0.001 -5.00 (-6.83, -3.09) <0.001 -5.01 (- <0.001 7.09, -2.92) Pre Hip Pain 0.53 (0.32, 0.74) <0.001 0.20 (-0.06, 0.46) 0.137 0.07 (- 0.629 Score 0.22, 0.36) Pre Hip Function - - 0.48 (0.37, 0.59) <0.001 0.50 <0.001 Score (0.37, 0.62) Pre SF12 PCS 0.54 (0.38, 0.71) <0.001 0.46 (0.26, 0.67) <0.001 0.50 <0.001 (0.27, 0.73) Pre SF12 MCS 0.16 (0.07, 0.24) <0.001 0.23 (0.13, 0.34) <0.001 0.25 <0.001 (0.13, 0.36) Surgical - - 3.58 (1.36, 5.80) 0.002 4.75 <0.001 Approach (2.29, 7.21) Cementation - - -0.88 (-2.91, 1.15) 0.393 -1.43 (- 0.219 3.71, 0.86) Femoral Head - - -0.67 (-0.28, 1.47) 0.540 -0.12 (- 0.922 Size 2.52, 2.28) K-L -4.76 (-6.45, -3.07) <0.001 -1.09 (-3.24, 1.06) 0.319 -1.33 (- 0.278 3.76, 1.08) Modified K-L -2.94 (-3.81, -2.08) <0.001 -0.28 (-1.39, 0.84) 0.625 -0.35 (- 0.585 1.59, 0.90) Joint Space -2.68 (-4.00, -1.36) <0.001 0.27 (-1.39, 1.92) 0.753 0.32 (- 0.732 Narrowing 1.54, 2.19) Pattern -3.08 (-4.38, -1.78) <0.001 -1.63 (-3.26, 0.01) 0.051 -2.22 (- 0.015 (none=0/hypertr 4.02, ophic=1/atrophic -0.43) =2) Supero- 1.51 (-0.36, 3.37) 0.113 -1.56 (-3.81, 0.69) 0.174 -1.97 (- 0.121 lateral=1/Medial- 4.47, concentric=2 0.52) Protrusio 0.98 (-2.60, 4.56) 0.591 -0.66 (-4.98, 3.65) 0.762 -1.34 (- 0.577 6.07, 3.39) Chondrocalcinosi -2.12 (-5.69, 1.46) 0.245 -4.92 (-9.20, -0.64) 0.024 -2.51 (- 0.345 s 7.73, 2.71) Bone Destruction -4.09 (-5.31, -2.87) <0.001 -0.43 (-2.00, 1.14) 0.593 -0.61 (- 0.492 2.34, 1.13) Osteophytosis 1.16 (-0.05, 2.37) 0.060 0.58 (-0.90, 2.05) 0.443 0.57 (- 0.497 1.08, 2.22) (B) Beta coefficient – Represents the magnitude of change in function score C: Patient characteristics (n=382) Mean + SD, Variable or Median (Range) n (%) Age (years) 68.9 + 9.3 70.0 (35.0, 91.0) **BMI (kg/m2) 29.9 + 5.5 29.1 (17.1, 50.4) ≠Pre-op SF-12 PCS 25.4 + 5.2 24.4 (14.4, 46.6) ∞Pre-op SF-12 MCS 49.3 + 10.5 51.2 (16.8, 72.0) €Pre-op Pain Score 11.6 + 4.1 10.0 (0.0, 40.0) €1 year Pain Score 38.7 + 9.0 44.0 (10.0, 44.0) €2 year Pain Score 38.8 + 9.0 44.0 (10.0, 44.0) £Pre-op Function Score 17.4 + 9.0 17.0 (0.0, 40.0) £1 year Function Score 33.7 + 10.8 36.0 (0.0, 47.0) £2 year Function Score 33.4 + 11.8 37.0 (2.0, 47.0) Ω Pre Total HHS 35.7 + 10.9 34.0 (10.0, 83.0) Ω 1 year Total HHS 80.6 + 16.6 86.0 (23.0, 100.0) Ω 2 year Total HHS 80.4 + 17.5 86.0 (20.0, 100.0) Change in Pain at 1 year 27.1 + 9.6 30.0 (-10.0, 40.0) Change in Pain at 2 years 27.1 + 9.5 30.0 (-10.0, 44.0) Change in Function at 1 year 16.2 + 10.9 17.0 (-15.0, 43.0) Change in Function at 2 years 15.9 + 11.8 16.5 (-18.0, 43.0) Change in Total HHS at 1 year 44.87 + 17.21 Change in Total HHS at 2 years 44.61 + 18.40 Gender Male 150 (39.3%) Female 232 (60.7%) Side Right 215 (56.3%) Left 167 (43.7%) American Society of 1 11 (2.9%) Anaesthesiologists (ASA) Score 2 208 (54.5%) 3 159 (41.6%) 4 4 (1.0%) Surgical Approach Hardinge 235 (61.5%) Posterior 136 (35.6%) Cementation Uncemented 70 (18.3%) Hybrid 269 (70.4%) Fully cemented 43 (11.3%) Femoral Head Size 28mm 306 (80.1%) 32mm 60 (15.7%) 36mm 16 (4.2%) Kellgren-Lawrence (K-L) grade 2 4 (1.0%) 3 151 (39.5%) 4 227 (59.4%) Modified Kellgren-Lawrence 2 4 (1.0%) grade 3a 26 (6.8%) 3b 125 (32.7%) 4a 95 (24.9%) 4b 132 (34.6%) Pattern Hypertrophic 43 (11.3%) Atrophic 44 (11.5%) Neither 294 (77.0%) Distribution Supero-lateral 232 (60.7%) Medial/concentric 146 (38.2%) Protrusio Yes 26 (6.8%) No 356 (93.2%) Chondrocalcinosis Yes 26 (6.8%) No 356 (93.2%) Bone Destruction None 242 (63.4%) Some 96 (25.1%) Severe 44 (11.5%) Osteophytosis None 19 (5.0%) Mild 153 (40.1%) Moderate 169 (44.2%) Severe 41 (10.7%) ** BMI - Body Mass Index (weight [Kg] / height [m]2) ≠ SF-12 PCS – Short Form 12 physical component score ∞ SF-12 MCS – Short Form 12 mental component score € HHS pain score ranges from 0 to 44, with higher scores indicating less £ HHS function score ranges from 0 to 47, with higher scores indicating better function Ω HHS total score ranges from 0 to 100, with a higher score indicating greater overall improvement. D. Intra-rater kappa values for the mK-L grade and individual radiographic features Radiographic Feature Kappa Value Modified K-L Grade 0.83 Joint Space Narrowing 0.75 Pattern (none=0/hypertrophic=1/atrophic=2) 0.77 Supero-lateral=1/Medial-concentric=2 0.65 Protrusio 0.88 Chondrocalcinosis 0.79 Bone Destruction 0.90 Osteophytosis 0.87</p><p>E. Mean Pain Scores according to mK-L Grade Mean + SD Variable Number Pre-op 1 year 2 years Change at 1 year Change at 2 years K&L <3a 30 11.33 + 3.46 36.48 + 10.91 35.71 + 11.62 25.10 + 12.53 24.29 + 12.54 K&L 3b 125 11.44 + 4.35 38.24 + 9.02 38.58 + 9.23 26.78 + 9.49 27.05 + 9.72 K&L 4a 95 12.21 + 4.42 38.68 + 9.67 38.92 + 8.92 26.45 + 10.27 26.62 + 9.82 K&L 4b 132 11.52 + 3.81 39.75 + 7.79 39.69 + 8.20 28.22 + 8.27 28.19 + 8.13</p><p>F. Mean Function Scores according to mK-L Grade Mean + SD Variable Number Pre-op 1 year 2 years Change at 1 year Change at 2 years K&L <3a 30 20.13 + 7.75 32.17 + 10.45 31.64 + 12.38 11.62 + 9.29 11.21 + 12.49 K&L 3b 125 20.58 + 9.11 34.81 + 10.12 34.72 + 10.67 14.12 + 11.14 14.03 + 11.38 K&L 4a 95 17.71 + 8.72 33.07 + 11.24 32.76 + 12.24 15.27 + 11.30 14.86 + 12.87 K&L 4b 132 13.42 + 7.69 33.32 + 11.12 32.91 + 12.36 19.94 + 9.77 19.53 + 10.39</p>