2D/4D Finger Length Ratio in the Screening of Developmental Dysplasia of the Hip.

Objective: To investigate whether there is a relationship between the 2nd finger and 4th finger length measurement ratios and developmental dysplasia of the Hip (DDH).
Study Design: Cross-sectional observational study. Place and Duration of the Study: Department of Orthopaedics and Traumatology, Meram Faculty of Medicine Hospital, Konya, Turkiye, from January 2020 to May 2023.
Methodology: Infants were screened for DDH with Graff method for the ultrasounds of both hips. Lengths of the 2nd and 4th fingers of both hands were measured and recorded. Patients with additional risk factors for developmental dysplasia of the hip (breech birth, family history, oligohydramnios, swaddling) were excluded.
Results: Two hundred and fifty-six babies were screened including 55.1% (n = 141) girls and 44.9% (n = 115) boys. Their mean age was 2.51 ± 0.80 months. The average lengths were 31.73 ± 3.05 mm, for the left 2nd finger and 34.26 ± 3.48 mm for the left 4th finger. In the hip USG measurements, the mean alpha angles were 62.91 ± 3.12° for the right hip and, 63.20 ± 3.55° for the left hip. Eighteen (7%) of babies who underwent hip ultrasound (USG) had unilateral or bilateral DDH. Among these cases, 2.7% (n = 7) had right, 2.3% (n = 6) had left, and 2% (n = 5) had bilateral DDH. There was no statistically significant correlation between the ratios of right 2/4 finger lengths and the right alpha angle (rs = 0.051; p = 0.421). There was a statistically positive and statistically significant correlation between the ratios of left 2/4 finger lengths and the left alpha angle (rs = 0.154; p = 0.013).
Conclusion: Only the left-hand finger ratio among the parameters in the model had a statistically significant effect on DDH. Therefore, the left hand 2D/4D finger length may be of value in screening for DDH.
Key Words: Developmental dysplasia of the hip, Second to fourth finger digit ratio, Ring finger, Digit ratios.