Kyoung Min Lee, MD, Chin Youb Chung, MD

Tae Won Kim, MD, Ki Hyuk Sung, MD, Bekzod Ahmedov, MD, Dong Yeon Lee, MD, Sang Hyeong Lee, MD, Dae Gyu

Kwon, MD, and Moon Seok Park, MD.

Department of Orthopaedic Surgery

Seoul National University Bundang Hospital, Republic of Korea

Which Radiographic Indices Should We Measure in Hallux

Valgus?

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• My disclosure is in the Final AOFAS Program Book.

• I have no potential conflicts with this presentation.

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Introduction

• Hallux valgus is a common 3D foot deformity.

• X ray measurements are performed on one plane and the relationship between the measurements of different planes has not been established.

• This study investigated the various measures to establish (1) the reliability; (2) relationship; and the ability to predict hallux valgus angle.

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Patients and Methods

• 732 patients who underwent radiographic evaluation for hallux valgus

• Radiographic indices included hallux valgus angle, intermetatarsal angle, interphalangeal angle, distal metatarsal articular angle, proximal phalangeal articular angle, simplified metatarsus adductus angle, first metatarsal protrusion distance.

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Data analysis

• Intra- and interobserver reliability

– ICC (intraclass correlation coefficient)

• Relationship between radiographic indices

– Pearson’s correlation coefficient

• Predictability for hallux valgus angle

– Multiple regression anlaysis

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Results

Table 1. Patients’ demographics and summary of radiographic measurements Patients’ and radiographic information Mean No. 732 Age (years) 51 (SD 17) Male:female 107: 625 Right:left 367: 365

Radiographic measurements HVA (°) 23 (SD 11; range, 5-70) IMA (°) 12 (SD 4; range, 2-36) IPA (°) 11 (SD 7; range, -16 to 65) DMAA (°) 11 (SD 8; range, -10 to 62) PPAA (°) 4 (SD 5; range, -12 to 29) Metatarsus adductus (°) 25 (SD 6; range, 6-53) First MT protrusion (mm) 2 (SD 3; range, -17 to 18) SRA (°) 9 (SD 13; range, -22 to 60) HVA = hallux valgus angle; IMA = intermetatarsal angle; IPA = interphalangeal angle; DMAA = distal metatarsal articular angle; PPAA = proximal phalangeal articular angle; Metatarsus adductus = simplified metatarsus adductus angle; First MT protrusion = first metatarsal protrusion distance; SRA = sesamoid rotation angle.

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Results

Table 2. Interobserver reliabilities of radiographic measurements Reliability HVA IMA IPA DMAA PPAA Metatarsus

adductus First MT protrusion

SRA

ICC (95% CI)

0.985 (0.975-0.992)

0.896 (0.832-0.940)

0.860 (0.777-0.919)

0.380 (0.149-0.592)

0.719 (0.579-0.829)

0.620 (0.452-0.760)

0.901 (0.836-0.943)

0.925 (0.875-0.958)

HVA = hallux valgus angle; IMA = intermetatarsal angle; IPA = interphalangeal angle; DMAA = distal metatarsal articular angle; PPAA = proximal phalangeal articular angle; Metatarsus adductus = simplified metatarsus adductus angle; First MT protrusion = first metatarsal protrusion distance; SRA = sesamoid rotation angle.

Table 3. Intraobserver reliabilities of radiographic measurements Reliability HVA IMA IPA DMAA PPAA Metatarsus

adductus First MT protrusion

SRA

ICC (95% CI)

0.989 (0.979-0.994)

0.914 (0.841-0.954)

0.884 (0.790-0.937)

0.781 (0.622-0.878)

0.819 (0.681-0.901)

0.756 (0.583-0.864)

0.944 (0.897-0.970)

0.952 (0.909-0.975)

HVA = hallux valgus angle; IMA = intermetatarsal angle; IPA = interphalangeal angle; DMAA = distal metatarsal articular angle; PPAA = proximal phalangeal articular angle; Metatarsus adductus = simplified metatarsus adductus angle; First MT protrusion = first metatarsal protrusion distance; SRA = sesamoid rotation angle.

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Results

Table 4. Correlation matrix of radiographic measurements

Radiographic measurements HVA IMA IPA DMAA PPAA

Metatarsus adductus

First MT protrusion

IMA 0.621 (< 0.001) IPA -0.438 -0.382 (0.001) (< 0.001) DMAA 0.636 0.467 -0.323 (< 0.001) (< 0.001) (< 0.001)

PPAA -0.363 -0.297 0.284 -0.284 (0.001) (< 0.001) (< 0.001) (< 0.001)

Metatarsus adductus

0.112 0.048 0.072 0.055 0.001

(0.002) (0.197) (0.051) (0.134) (0.972) First MT protrusion

0.375 0.196 -0.113 0.246 -0.116 0.256

(< 0.001) (< 0.001) (0.002) (< 0.001) (0.002) (< 0.001)

SRA 0.598 0.470 -0.348 0.461 -0.353 -0.071 0.203 (< 0.001) (< 0.001) (< 0.001) (< 0.001) (< 0.001) (0.060) (< 0.001) HVA = hallux valgus angle; IMA = intermetatarsal angle; IPA = interphalangeal angle; DMAA = distal metatarsal articular angle; PPAA = proximal phalangeal articular angle; Metatarsus adductus = simplified metatarsus adductus angle; First MT protrusion = first metatarsal protrusion distance; SRA = sesamoid rotation angle.

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Results

Table 5. Multiple regression analysis to identify significantly contributing radiographic measurements to hallux valgus angle

Radiographic measurements Non-standardized Standardized

beta t p value B Standard error

Coefficient 5.798 1.508 3.845 < 0.001 IMA 0.794 0.085 0.265 9.325 < 0.001 IPA -0.218 0.046 -0.125 -4.747 < 0.001 DMAA 0.388 0.037 0.296 10.536 < 0.001 PPAA -0.095 0.062 -0.039 -1.523 0.128

Metatarsus adductus 0.108 0.041 0.064 2.622 0.009

First MT protrusion 0.588 0.094 0.157 6.287 < 0.001

SRA 0.212 0.024 0.251 8.694 < 0.001 IMA = intermetatarsal angle; IPA = interphalangeal angle; DMAA = distal metatarsal articular angle; PPAA = proximal phalangeal articular angle; Metatarsus adductus = simplified metatarsus adductus angle; First MT protrusion = first metatarsal protrusion distance; SRA = sesamoid rotation angle.

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Conclusion

• Hallux valgus angle, intermetatarsal angle, interphalangeal angle, sesamoid rotation angle, and first metatarsal protrusion distance are worth measuring in the hallux valgus deformity considering their reliability and predicting the three-dimensional hallux valgus deformity.

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Thank you !