Extra-Osseous TaloTarsal Stabilization Devices


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This report describes the difference between a type I subtalar arthroereisis device and a type II non-arthroereisis device used to stabilization a talotarsal joint dislocation.

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Extra-Osseous TaloTarsal Stabilization Devices

  1. 1. Extra-Osseous Stabilization Devices: A New Classification System Journal of Foot and Ankle Surgery, Volume 51, Issue 5 , Pages 613-619, September 2012 Michael E. Graham, DPM, FACFAS, Nikhil T. Jawrani, MSPurpose Results/Classification System ParametersThe purpose of this study was to classify the various  Type I Devices:extra-osseous talotarsal stabilization (EOTTS) devices o Cylindrical (IA) or Conical (IB) in shape.into categories by design features and biomechanical o Inserted in a lateral-to-medial/obliquefunction. These differences may have an impact on the orientation.success rates of each type. This classification system o Leading anterior edge inserted up to thewill help surgeons appreciate these differences and the longitudinal talar bisection.associated benefits, which in turn will aid them when o Laterally anchored by soft tissues in the sinusmaking patient care decisions. portion of the tarsal sinus. o Function by an impingement mechanism (blockBackground excessive motion).Many treatment options have been used to correct the  Type II Devices:partial dislocation of the talus on the tarsal mechanism o Lateral conical and medial cylindrical geometry.(RTTD), a dynamic deformity that has been shown to be o Inserted anterior-distal-lateral to posterior-the primary etiology for many pathologies of the foot proximal medial.and ankle. EOTTS has been a controversial surgical o Leading anterior edge inserted medially beyondoption. It offers improved stabilization over external the longitudinal talar bisection.measures and is less invasive than traditional hindfoot o Medially anchored by soft tissues within thereconstructive surgery. Over the years, many subtalar canalis portion of the tarsal sinus.devices have been introduced, which differ in design, o Function by allowing normal helicoidal motionmaterials, orientation and biomechanical function. of the talus on the tarsal mechanism.Previous classification systems have been published,however, due to the introduction of a new implant design Clinical Significance & Conclusionsand function, it was thought it would be beneficial to  The partial/recurrent dislocation of the talus on thepresent an updated classification system. tarsal mechanism is a triplane deformity. Displacement on any one of the four articular facetsMethods of the TTM leads to displacement at the other facets. Four critical design/function aspects were determined  The ideal method to stabilize the TTM is exactly at on which to base classification: the axis of triplanar talotarsal motion. In the TTM, o Device geometry/shape. this is referred to as the “cruciate pivot point” and is o Anatomic orientation within the sinus tarsi. generally located at the entrance of the canalis tarsi o Anchoring location within the tarsal sinus. along the longitudinal talar bisection line. o Mechanism of talar stabilization and  It has been acknowledged that a device that better biomechanical function. matches the anatomical shape of the tarsal sinus and Two major categories were established – Type I and follows its natural orientation would allow for better Type II devices. Type I devices were further sub- biomechanical functioning. classified into Type IA and Type IB.  Only Type II devices meet the ideal parameters, which has an impact on their improved success rates.  This improved design and function may also contribute to the success of Type II devices in decreasing the effects of or even eliminating secondary pathologies. Additional Scientific Papers on HyProCure® are available. Visit the Library section on: www.GraMedica.com