The anatomical variations of the extensor tendons to the dorsum of the hand.

To lead a quality life, tendon repair must be performed in a trauma causing damage to the extensor tendon of the hand. The aim of this study is to study the structures that can be used as donor tendons. Fifty-four dissected adult hands were examined to study the pattern of the extensor tendons on the dorsum of the hand. The most common distribution patterns of the extensor tendons of the fingers were as follows: a single extensor indicis proprius (EIP) tendon which inserted ulnar to the extensor digitorum (ED)-index; a single ED-index; a single ED-middle; a single ED-ring; an absent ED-little; a double extensor digiti minimi (EDM), and a single ED-ring to the little finger. The frequency of the number of tendons is as follows: a single (87.03%) EIP, a single ED-index (100%), a single (92.6%) ED-middle, a single (75.9%) ED-ring, and an absent (68.5%) or a single (24.1%) ED-little. A double (88.9%) EDM tendons were seen. The thickest type of juncturae tendinum (JT) is found primarily between the ring and little fingers (90%). Suitable excessive tendon and the thickest JT as donor tendon were found in the fourth intermetacarpal space. The present findings, especially the fourth intermetacarpal space, may explain why incisions on the dorsum of the hand should be large and performed with particular care. It is necessary to have a thorough understanding of the arrangements of the multiple extensor muscles and their junctural connections of the hand when tenoplasty or tendon transfer is required.