Anatomical attachments to the proximal phalangeal base--a case for stability.

Transverse midshaft fractures of the proximal phalanx are often unstable and require open reduction and internal fixation. In contrast, fractures of the base of the proximal phalanx are occasionally amenable to conservative treatment in the form of manipulation and a graded mobilisation programme. This stability may be the result of splinting of the fracture by the surrounding anatomical structures, but to our knowledge this has not been previously elucidated anatomically. In this study we define the extent of attachment of the various anatomical structures to the base of the proximal phalanx. The contribution of the joint capsule, collateral ligaments, accessory collateral ligaments, interosseous muscles, and volar (palmar) plate may confer stability to fractures in the proximal 6-9 mm range at the base of the proximal phalanx, once they are reduced and immobilised in the correct positions.