Anatomical similarity between tendons and Type 3 intertendinous connections: suitability as local donor tissue

Objective: A detailed anatomical knowledge of the extensor tendons of the hand is essential for accomplishing successful tendon repair. The aim of this study was to investigate the similarities between the extensor tendon and the thickest intertendinous connections (IC) in the 4th intermetacarpal space, where Type 3 IC is most frequently seen. Methods: A total of 38 dissected hands were studied for anatomical structures that might serve as donor extensor tendons as well as for their relationship with the IC in the fourth intermetacarpal space of the dorsal hand. Results: The most frequent anatomical pattern in the extensor tendons of the fourth intermetacarpal space were the two tendons from the extensor digiti minimi muscle (68.5%) and the thickest type of IC (90%). Other common findings detected at microscopy included the presence of a capsule in the structures associated with the tendon and IC, rich vascularization and high collagen content. Conclusion: Type 3 IC resembles tendons in strength and because of its histological similarity, the IC may be suitable to use in tendon repair. The fourth intermetacarpal space appeared to have the greatest tendon length and thickest IC content and is therefore a suitable donor graft tissue for local tendon repair.