title: Development of an internally braced prosthesis for total talus replacement.
abstract: Total loss of talus due to trauma or avascular necrosis, for example, still remains to be a major challenge in foot and ankle surgery with severely limited treatment options. Implantation of a custom made total talar prosthesis has shown promising results so far. Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle. Therefore, our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability. A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R. prosthesis (Stryker). Additionally, four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments. Two modifications can be provided according to the clinical requirements: A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R. total ankle replacement system. A feasibility study was performed using a fresh frozen human cadaver. Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus, valgus or sagittal stress with 150 N. Correct implantation of the prosthesis was technically possibleviaan anterior approach to the ankle and using standard instruments. Malleolar osteotomies were not required. Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees. Maximum anterior displacement of the talus was 6 mm, maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees. Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Regauer
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Lange
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Soldan
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Peyerl
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Baumbach
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Böcker
authors.affiliation: Markus Regauer, Mirjam Lange, Sebastian Baumbach, Wolfgang Böcker, Hans Polzer, Klinik für Allgemeine, Unfall und Wiederherstellungschirurgie, Klinikum der Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Polzer
keywords: Ankle; Avascular necrosis; Hemiprosthesis; InternalBrace; Prosthesis; Talus replacement; Total loss of talus