Table 3 Risk factors for OA progression after RAO assessed by univariate and multivariate regression analyses

  Age at the time of surgery

1.051

1.011–1.093

0.013

  Body mass index

0.996

0.847–1.170

0.957

  Smoking history

0.555

0.213–1.451

0.230

  Presence of cysts

1.398

0.710–2.752

0.333

  Deformity of the femoral head

0.895

0.389–2.063

0.795

  Center edge angle (°)

0.998

0.962–1.035

0.911

  Sharp angle (°)

0.961

0.888–1.039

0.315

  Acetabular head index (%)

1.000

0.963–1.037

0.981

  Acetabular roof obliquity (°)

1.015

0.965–1.067

0.572

  Obturator foramen-head distance (mm)

1.074

0.970–1.188

0.169

  Joint space width (mm)

0.961

0.819–1.126

0.621

  Radiographic stage

1.028

0.664–1.592

0.902

  Center edge angle (°)

0.996

0.971–1.023

0.783

  Sharp angle (°)

1.014

0.972–1.058

0.520

  Acetabular head index (%)

1.001

0.969–1.035

0.935

  Acetabular roof obliquity (°)

0.999

0.974–1.026

0.959

  Obturator foramen-head distance (mm)

0.925

0.855–1.001

0.052

  Joint space width (mm)

0.953

0.763–1.189

0.669

  Radiographic stage

0.808

0.459–1.425

0.462

  Joint congruity

0.997

0.680–1.460

0.986

  Thickness of the transferred acetabulum

0.887

0.800–0.982

0.022

 Age at the time of surgery

1.047

1.005–1.091

0.028

 Thickness of the transferred acetabulum

0.923

0.829–1.027

0.142