Safe zones at the medial and lateral calcaneus for percutaneous pin placement: an anatomical study

Abstract

Objective To determine safe zones at the medial and lateral calcaneus for percutaneous pin placement in Chinese patients.Methods Fourteen cadaveric specimens of normal Chinese adult foot and ankle joints were dissected in this study.At the medial calcaneus of each foot, the most medial and posteroinferior point, the most inferior medial malleolus and the navicular tuberosity were identified and labeled as points A, B and C respectively.The medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve, the posterior tibial artery, the lateral plantar artery and the medial plantar artery were carefully dissected and identified.A relative safe zone at the medial calcaneus was marked off according to where the neurovascular structures crossed lines AB and AC.At the lateral calcaneus, the most lateral and posteroinferior point and the inferior lateral malleolus were identified and labeled as points D and E respectively.The lateral calcaneal nerve, the sural nerve and the trunk of the small saphenous vein were carefully dissected and identified.A relative safe zone at the lateral calcaneus was marked off in the same way as that at the medial calcaneus.Results At the medial calcaneus, the medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve and the posterior tibial artery crossed line AB respectively at posteroinferiorly 22%, 50%,56%, 64% and 58% of the line.The medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve, the lateral plantar artery and the medial plantar artery crossed line AC respectively at posteroinferiorly 14%, 39%, 49%, 63%, 41% and 57% of the line.At the lateral calcaneus, the lateral calcaneal nerve, the sural nerve and the trunk of the small saphenous vein crossed line DE respectively at posteroinferiorly 19%, 65% and 61% of the line.Conclusions At the medial calcaneus, the circular region posterior to the 1/2 of line AB and to the 1/3 of line AC may be considered as a relative safe zone for percutaneous pin placement; at the lateral calcaneus, the region posterior to the perpendicular at the midpoint of line DE may be considered as a relative safe zone for percutaneous pin placement. Key words: Calcaneus; Medial plantar merve; Dissection