title: A modified and enhanced test setup for biomechanical investigations of the hindfoot, for example in tibiotalocalcaneal arthrodesis.
abstract: Tibiotalocalcaneal arthrodesis (TTCA) using intramedullary nails is a salvage procedure for many diseases in the ankle and subtalar joint. Despite "newly described intramedullary nails" with specific anatomical shapes there still remain major complications regarding this procedure. The following study presents a modified biomechanical test setup for investigations of the hindfoot.
  
  
  
  Nine fresh-frozen specimens from below the human knee were anaysed using the Hindfoot Arthrodesis Nail (Synthes) instrument. Quasi-static biomechanical testing was performed for internal/external rotation, varus/valgus and dorsal/plantar flexion using a modified established setup (physiological load entrance point, sledge at lever arm to apply pure moments). Additionally, a 3D optical measurement system was added to allow determination of interbony movements.
  
  
  
  The mean torsional range of motion (ROM) calculated from the actuator data of a material testing machine was 10.12° (SD 0.6) compared to 10° (SD 2.83) as measured with the Optotrak® system (between tibia and calcaneus). The Optotrak showed 40 % more rotation in the talocrural joint. Mean varus/valgus ROM from the material testing flexion machine was seen to be 5.65° (SD 1.84) in comparison to 2.82° (SD 0.46) measured with the Optotrak. The subtalar joint showed a 70 % higher movement when compared to the talocrural joint. Mean ROM in the flexion test was 5.3° (SD 1.45) for the material testing machine and 2.1° (SD 0.39) for the Optotrak. The movement in the talocrural joint was 3 times higher compared to the subtalar joint.
  
  
  
  The modified test setup presented here for the hindfoot allows a physiological biomechanical loading. Moreover, a detailed characterisation of the bone-implant constructs is possible.
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Evers
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Dominic
authors.initials: D
authors.lastname: Gehweiler
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Lakemeier
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Raschke
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Wähnert
authors.affiliation: Department of Trauma-, Hand- and Reconstructive Surgery, University Hospital Muenster, Albert-Schweitzer-Campus 1, Building W1, 48149, Muenster, Germany. sabine.ochman@ukmuenster.de.
authors.forename: Sabine
authors.initials: S
authors.lastname: Ochman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000503:physiopathology* / Q000601:surgery; D001174:Arthrodesis / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D001696:Biomechanical Phenomena; D001858:Bone Nails; D002111:Calcaneus / Q000601:surgery; D005260:Female; D005528:Foot / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D016059:Range of Motion, Articular; D012399:Rotation; D013380:Subtalar Joint / Q000503:physiopathology* / Q000601:surgery; D013628:Talus / Q000601:surgery; D013977:Tibia / Q000601:surgery
keywords: Biomechanics; Hindfoot; Intramedullary nailing; Tibiotalocalcaneal arthrodesis