gms | German Medical Science

Objectives/Interrogation: Congenital thumb hypoplasia is a malformation involving abnormal development and differentiation in the longitudinal radial axis. Various surgical reconstructions are available for each deficiency, but empirical evidence that allows for evaluation of the results of the different techniques is scarce. This retrospective study analyses the outcomes of patients who underwent surgical reconstruction for congenital thumb hypoplasia in our institution.

Methods: All patients who underwent surgical reconstruction for congenital thumb hypoplasia, performed by the senior author, and for whom a minimum of 3 years of follow-up data were available, were identified by a retrospective records review and were recalled for clinical assessment. Case notes, clinical assessments, and radiological data obtained from the medical records were reviewed. At follow-up, objective and subjective measurements were conducted.

Results and Conclusions: From 32 reconstructions for thumb hypoplasia in 29 patients, 19 patients (22 affected thumbs) could be included for analysis. The mean (SD) follow-up duration was 9.0 (3.9) years (range 3.6 years - 16.2 years). Our results for range of motion and subjective parameters are in line with data from comparable studies. The percentage of unstable metacarpophalangeal (MP) joints in this study was relatively high (45.5% in extension and 72,7% in 30° flexion) compared to the literature. Imbrication of local tissue alone at the ulnar side of the MP joint for ulnar collateral ligament reconstruction seems to stretch and fail with time. Furthermore, a secondary arthrodesis due to painful instability at the MP joint was required in four patients. The abductor digits minimi (ADM) was the preferred method to restore opposition in our study in most cases. Compared to studies that used predominantly a Flexor digitorum profundus (FDS) opposition transfer, our patients had higher results in grip strength (77% of normal), despite the higher number of MP joint instability. However, the inconsistency of application of pre-operative classification is a problem with most outcomes studies on this topic and renders comparison difficult. The establishment of a valid, age-related assessment method for thumb hypoplasia, which considers preoperative measurements, includes intraoperative findings, and is applicable in the preoperative age category (1-3 years) would be a valuable contribution for the future.