gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2013)

22.10. - 25.10.2013, Berlin

Evaluation of a static pes cavus model based on changes of the osseous architeture

Meeting Abstract

  • presenting/speaker Timo Schmid - Orthopädische Klinik, Inselspital Bern, Bern, Switzerland
  • Sebastian Zurbriggen - Orthopädische Klinik, Inselspital Bern, Bern, Switzerland
  • Boyko Gueorguiev - AO Research Institute, Davos, Switzerland
  • Ivan Zderic - AO Research Institute, Davos, Switzerland
  • Fabian Krause - Universität Bern, Inselspital, Klinik für Orthopädische Chirurgie, Bern, Switzerland

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2013). Berlin, 22.-25.10.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocIN22-1193

doi: 10.3205/13dkou017, urn:nbn:de:0183-13dkou0172

Published: October 23, 2013

© 2013 Schmid et al.
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Outline

Text

Objective: Typical clinical feature of pes cavovarus are an elevated longitudinal arch and a neutral of even varus hindfoot. This leads to anteromedial joint contact stresses. As opposed to pes planovalgus to date there is no generally accepted laboratory model simulating pes cavovarus in literature. In one description a model was created using different configurations of tendon pulls. However with this model the typical changes in the osseos architecture could not be achieved. Therefore we evaluated a model which is based altering the osseos architecture.

Methods: 8 cadaver specimen were used to create a cavovarus model. After opening the tarsometataral (TMT) joints 1-3 dorsally a 30° angle was put in the TMT 1 joint. The talonavicular joint capsule was opened laterally to allow forefoot adduction. Every foot was put on an Polymetacrylat embedding to prevent collapse of the arch during the testings.

CT Scans were performed before and after applying the model with a static load of 300N -(half-body weight).

Navicular height, lateral and dorsoposterior talometatarsal 1 angle, calcaneal pitch angle, inclination of the talus and metatarsal 1, talonavicular coverage angle and to evaluate the hindfoot varus anteroposterior tibiocalcanear angle were measured.

Additionally the medialisation of the centre of force in the ankle joint was determined by using intraarticular pressure sensors.

Results and conclusion: Regarding the high longitudinal arch significant changes could be seen regarding the navicular height (3.0cm to 3.9 cm, p=0.005), lateral talometatarsal 1 angle (-3.7° to 17.2°, p=0.005) and the inclination of the first metatarsal (19.6° to 33.0°, p = 0.005)

The forefoot adducted with an increase of the talonavicular coverage angle (-8.4° to + 16.4°, p=0.005) and the dorsoplantar first talometatarsal angle (0° to 21.8°, p=0.005).

The hindfoot showed an increase in the calcaneal ptich angle (21.2° to 23.7° p=0.03) and a decrease of talar inclination (23.3° to 15.8°, p=0.005).

The hindfoot showed an varisation (anteroposterior tibiocalcaneal angle -9.8° to +1.5°, p = 0.005)

The ankle pressure measurements showed a significant medialisation of the centre of force of 6.5mm (p=0.017) without a significant shift in anteroposterior direction (p=0.33)

A cavovarus model based on altering the osseos architecture was evaluated. Significant chanches in the configuration of the longitudinal arch, forefoot adduction and hindfoot varus could be reproduced. The changes led to the typical medial overloading of the ankle joint. This model can be used to evaluate different procedures done in cavovarus correction.