## Background

^{®}software program), stored electronically, and retrieved with a computer. Computer-assisted analysis of skeletal radiographs is increasingly introduced in the field of hallux valgus [23‐29].

## Methods

### Angular measurements

^{®}S40).

^{®}(Autodesk Inc., San Rafael, California, USA). The HVA was categorized as normal (< 15°), mild (15–20°), moderate (21–39°), and severe (≥ 40°); the IMA as normal (< 9°), mild (9–11°), moderate (12–17°), and severe (≥ 18°); and the PPAA as normal (< 6°), mild (6–10°), moderate (11–20°), and severe (≥ 21°).

### Perpendicular bisectors of the longitudinal axes of the first metatarsal and proximal phalanx

^{®}program computed the location of the IP and the length of a line segment (named 'DL' = distance length) joining the IP and the longitudinal metatarsal and phalangeal axes. Two categories were established for the site of the IP: inside the foot and outside the foot. Width of the foot was measured radiographically as the distance between the maximal prominence of the fifth and first metatarsals.

### First metatarsophalangeal arc circumference

^{29}

### Clinical assessment of hallux valgus severity

^{®}S40). For this weightbearing view, the patient stands with their toes pointing straight ahead, knees fully extended, and weight distributed evenly on both feet. The medial border of the foot was aligned to avoid internal or external rotation of the leg. The camera was strictly positioned perpendicularly to the bearing surface of the foot, for which a tripod and a spirit level were used. The distance was not standardized; for each case the distance necessary so that the foot occupied the entire screen area was selected. Each foot was photographed separately. A representative image of a clinical photograph is shown in Figure 4. Three independent observers rated the severity of hallux valgus in forefoot photographs using a visual analogue scale (VAS) The VAS consisted of a 100 mm horizontal line, the left end representing 'normal appearance or absence of hallux valgus deformity' (0 mm) and the right 'maximum hallux valgus deformity' (100 mm). Each observer was unaware of the purpose of the study and blinded regarding other observers' assessments.

### Statistical analysis

## Results

Angle | Severity | No. cases | Percent |
---|---|---|---|

HVA | Normal, < 15° | 35 | 12 |

Mild, 15–20° | 42 | 13 | |

Moderate 21–39° | 153 | 51 | |

Severe, ≥ 40° | 71 | 24 | |

IMA | Normal, < 9° | 58 | 19 |

Mild, 9–11° | 76 | 25 | |

Moderate, 12–17° | 135 | 45 | |

Severe, ≥ 18° | 32 | 11 | |

PPAA | Normal, < 6° | 116 | 38 |

Mild, 6–10° | 115 | 38 | |

Moderate, 11–20° | 63 | 21 | |

Severe, ≥ 21° | 7 | 2 |

Data | Mean (SD), mm | Pearson's r coefficient | p value |
---|---|---|---|

VAS scores | |||

Observer 1 | 32.0 (19.0) | ||

Observer 2 | 37.5 (19.9) | ||

Observer 3 | 36.8 (20.9) | ||

s-VAS* | 35.4 (20.0) | ||

Agreement | |||

Observer 1 vs 2 | 0.873 | < 0.001 | |

Observer 1 vs 3 | 0.856 | < 0.001 | |

Observer 2 vs 3 | 0.876 | < 0.01 | |

s-VAS* | |||

Intersection point site | |||

Inside the foot | 52.8 (14.7) | < 0.001 ^{†}
| |

Outside the foot | 25.3 (14.3) |

Site of the intersection point | p value | ||
---|---|---|---|

Variables | Inside the foot | Outside the foot | Inside vs outside the foot |

HVA | 42.5 (7.5) | 23.1 (8.8) | < 0.001 |

IMA | 15.1 (3.3) | 10.7 (3.0) | < 0.001 |

PPAA | 7.4 (5.6) | 7.6 (4.5) | 0.802 |

Data | Pearson's correlation coefficient | p value |
---|---|---|

HVA | 0.857 | < 0.001 |

IMA | 0.823 | < 0.001 |

PPAA | 0.579 | < 0.001 |

Distance length | -0.694 | < 0.001 |

Univariate | Multivariate | |||||
---|---|---|---|---|---|---|

Correlation index | Beta coefficient | p value | R | Beta coefficient | p value | |

HVA | -0.805 | -1.412 | < 0.001 | 0.870 | -0.531 | < 0.001 |

IMA | -0.523 | -0.278 | < 0.001 | 0.425 | -0.074 | 0.064 |

PPAA | 0.015 | 0.010 | 0.795 | 0.151 | 0.044 | 0.484 |