[Description of an original conservative method for the surgical management of the Blauth IIIb thumb hypoplasia: "relative lengthening - thumb stabilization"]

Problematic: Thumb hypoplasia is a rare congenital hand disorder. Despite the recent clarifications concerning many surgical indications, dealing with Blauth IIIb type remains a polemic subject. We hereby suggest "The relative lengthening - thumb stabilization", an original and simple conservative surgery technique for the Blauth IIIb type, in order to satisfy parents and big kids requests of a "five fingered hand". The whole hypoplastic thumb is lowered in a way that lengthens it relatively. An intentional pseudarthrosis is performed between the first metacarpal base and the second metacarpal diaphysis, creating a "new trapeziometacarpal joint".

Patients and methods: The suggested technique was performed on four IIIb type hypoplasic thumbs of three kids since 1997.

Results: The average postoperative follow-up is 9.6years (3.5 to 12.5years). The average Kapandji score is 5.75 (5 to 6). The key pinch prehension strength is by 21.5% in relation to the normal hand and the global prehension strength (according to Jamar Test) is by 67%. The global pinch is possible and natural in all cases.

Discussion and conclusion: The surgical management of the type IIIb thumb hypoplasia is a real challenge. We regard this technique of relative lengthening with thumb stabilization as an interesting alternative to the other microsurgical conservative surgeries.