ICOPLAST Award of Excellence: Robert Dijkman

Netherlands / The Netherlands Society of Plastic Surgery

Thumb strength and manual ability in radial polydactyly types II and IV

Abstract

Purpose: The aims of this international multicenter study were to quantify strength impairment in radial polydactyly types II and IV, to assess which factors affect thumbs strength, and to evaluate the impact of thumb strength impairment on manual ability.

Methods: Postoperative thumb strength was measured in patients with unilateral radial polydactyly type II and IV. Strength of the unaffected contralateral side was used as the reference. Radial polydactyly type, hand dominance, thenar hypoplasia, number of surgeries, sex, age at follow-up, duration of follow-up, instability, and thumb size were evaluated as determinants of thumb strength. Self-reported manual ability was measured using the ABILHAND-kids questionnaire.

Results: In the 80 patients included in this study, thumb strength was impaired to 86% – 94% of the unaffected contralateral thumb. Strength impairment was influenced by hand dominance, thumb size, and number of surgeries. Thumbs were 10% – 29% stronger on an affected dominant hand, compared to thumbs on an affected non-dominant hand, with exception of metacarpophalangeal joint flexion strength. Increased thumb size was positively correlated with pinch strengths, whereas increased number of surgeries showed a negative correlation. Forty-three (54%) patients attained the maximum score in the ABILHAND-kids questionnaire. There was no correlation between relative thumb strength and manual ability.

Conclusions: The small but statistically significant strength impairment of radial polydactyly patients does not impair their perceived manual ability. Strength is better in radial polydactyly cases with an affected dominant hand and in cases with relatively larger thumbs, while need for revision surgeries is associated with greater strength impairment.