Intramedullary fixation with bioabsorbable and osteoconductive hydroxyapatite/poly-L-lactide threaded pin in digital replantation

Abstract

In digital replantation, Kirschner wire (K-wire) fixation has commonly been used for osteosynthesis. On the other hand, K-wires are often obtrusive because of protrusion from the replanted digit. We describe a case series treated using hydroxyapatite/poly-L-lactide (HPLLA) threaded pins, which are not only bioabsorbable, but also osteoconductive, for osteosynthesis in crushed amputation or comminuted fracture, including distal phalanx amputation. Using an HPLLA threaded pin, 10 digital replantations were performed between July 2016 and April 2018. The precisely cut pin is manually pushed into the fracture site as an intramedullary nail. The pin is first pushed into the distal site, and then into the proximal site, after drilling with a K-wire of the same diameter as the pin. All amputations were crush type, and levels of amputations were Tamai zone I in three cases, zone II in two and zone III in five. Eight of the 10 digits survived. The two digits that did not survive showed venous insufficiency. Bone union of the eight digits was successfully obtained after 9–19 weeks (median 12 weeks). No adverse events occurred such as distortion of the pin, infection or foreign body reaction. The HPLLA threaded pin may be an adequate device to fix fractures in digital replantation.