gms | German Medical Science

Objectives/Interrogation: Congenital clasped thumb is a thumb flexion adduction deformity that may present as an isolated anomaly or as part of a spectrum of complex congenital anomalies. First web release may be indicated in selected cases. We present experience of our surgical technique using a systematic anatomical approach to first web release.

Methods: A casenote based retrospective review of global first web release procedures undertaken to treat clasped thumb in our unit between 2013-2018 was performed.

Results and Conclusions: 16 first web releases were undertaken in 11 patients. 8/11 patients had a diagnosis of arthrogryposis. Three patients had a defined syndrome (1) Klinefelter's syndrome (2) Pena-Shokeir Syndrome (3) Freeman-Sheldon Syndrome. Associated congenital anomalies included gastroschisis and ventricular septal defects.

Mean age at primary surgery was 58 months. An anatomical approach to first web release was undertaken addressing sequentially skin, palmar fascia, flexor retinaculum, thenar muscle, adductor pollicis, first dorsal interosseous, flexor pollicis longus, joints. A curvilinear incision was made extending from the free margin of the first web to the wrist. Augmentation of palmar skin shortage was by transposition flap from the index finger (10/16), full thickness skin graft (12/16), Z-plasty (7/16). In cases with significant finger flexion deformity we inset the index finger flap transversely in the palm. Release of anomalous fascial bands was required in all hands. Release of flexor retinaculum (15/16) reduced the deforming force of tight thenar muscle. Additional release of thenar muscle origin was required in 4/16 hands. Adductor pollicis origin was released in 4/16 hands, intramuscular tenotomy of insertion in 7/16. 1st dorsal interosseous origin was released (2/16), tendon step-lengthened (1/16). Flexor pollicus longus intramuscular tenotomy was required in 3 cases. K-wires were used to temporarily stabilize the metacarpophalangeal joints/maintain 1st web in 6/16 webs. Concommitant procedures were undertaken for (i) finger flexion deformities (7/16), (ii) to augment extensor function (3/16).

Treatment of the first web in congenital clasped thumb can be challenging. The principles of surgical management - sequential release and augmentation of web structures can be achieved in different ways depending on operative findings. Here we demonstrate our anatomical technique and approach to the first web.