Anatomic Classifications and Functional Outcomes in Preaxial Polydactyly of the Hand

BACKGROUND: Preaxial polydactyly is a common congenital hand anomaly with substantial anatomic variability. Although several classification systems exist, the relationship between anatomic subclassification and postoperative outcomes remains incompletely defined. This study evaluated clinical and radiographic outcomes after surgical reconstruction, compared associations of the Wassel-Flatt (WF) and JK classifications with outcomes, and assessed the Japanese Society for Surgery of the Hand (JSSH) and Rotterdam scoring systems. METHODS: We retrospectively reviewed 58 patients (59 thumbs) treated surgically between 2012 and 2024. Thumbs were classified using the WF and JK systems. Final outcomes included range of motion, alignment, stability, JSSH and Rotterdam scores, and reoperation. Associations with classification subtype, surgical procedures, and temporary transarticular K-wire fixation were analyzed at the thumb level. RESULTS: WF type IV and JK type IV were the most common categories. Total range of motion exceeded 70 degrees in 39 thumbs, and joint stability was preserved in 52. Fifty-three thumbs had good or excellent outcomes acoording to JSSH criteria; the mean Rotterdam score was 27.1±2.5. Eleven thumbs were classified differently by the 2 systems. Of 29 WF type IV thumbs, 26 remained JK type IV and 3 were reclassified as JK type VIIB; the latter had lower JSSH total and functional scores. Overall, the JK classification was associated with postoperative alignment and JSSH total score, although the small type VIIB subgroup limits interpretation. Temporary K-wire fixation was associated with lower interphalangeal joint and total range of motion and lower functional scores; however, confounding by deformity severity and reconstruction complexity cannot be excluded. No reoperations were required during the available follow-up period. CONCLUSIONS: Surgical reconstruction yielded favorable outcomes in most patients. The JK classification provided additional anatomic granularity, particularly by identifying a small type VIIB subgroup within heterogeneous WF categories, but its prognostic value requires validation in larger cohorts. Temporary K-wire fixation was associated with reduced postoperative motion without establishing causation. The JSSH and Rotterdam instruments provided complementary outcome assessment. LEVELS OF EVIDENCE: Level III-retrospective comparative study.