Closed Injuries: Bone, Ligament, and Tendon

Mallet fingers are clearly far more complex to care for correctly than they appear. Patients often present to the clinic with a mallet finger, wondering why they suddenly cannot extend the tip of their finger after what appeared to be a trivial injury such as pulling up socks or tucking in a bed sheet ([1]; Fig. 2.1). Other patients describe a high-velocity sports or work impact on the finger, usually an axial load onto the fingertip or the dorsum of the fingertip [2]. Although mallet fingers may appear to be somewhat inconsequential, up to 25 % of patients miss 6 weeks of work, sports, and even activities of daily living [3]. An eccentric axial load to the tip of the finger causing the distal interphalangeal (DIP) joint to forcefully hyperflex or hyperextend can disrupt the continuity of the insertion of the conjoined lateral bands onto the dorsal aspect of the distal phalanx. This avulsion may take the form of tendon avulsion off the dorsal lip of the proximal end of the distal phalanx or an intra-articular fracture of the dorsal lip may occur with the bony fragment still attached to the terminal extensor (Fig. 2.2). The dorsal fragment’s size and degree of articular involvement may vary from a fleck of bone to 70–80 % of the joint surface. Any joint involvement greater than 50 % is generally associated with volar subluxation of the DIP joint (Fig. 2.3). With the flexor digitorum profundus (FDP) tendon unopposed, the tip of the finger will assume a flexed posture. Initially thought of as a “jammed finger” of minor importance, it is frequently ignored. The characteristically flexed posture of the distal phalanx is usually detected immediately but sometimes may only manifest after several weeks once the swelling has subsided. Patients that seek medical attention within 2–3 weeks of injury can usually be treated nonoperatively. Others may wait up to 3 or 4 months after the full extent of the disability become manifest such as DIP joint pain, erythema, skin breakdown, DIP flexion contracture, swan-neck deformity, and difficulty in navigating tight spaces such as a back pocket. While it is possible to commence nonoperative treatment, these may fail to correct the deformity and thought must be given to surgical correction [4]. Alternatively, there are patients who have undergone conservative treatment for 3–4 months only to find that the flexion deformity has persisted or recurred. In those patients, there have been weak or incomplete reattachment of the tendon end back to bone and the connection may be nothing more than a thin, transparent scar bridge with the tendon having retracted more than 3 mm ([5]; Fig. 2.4). This proximal retraction of the extensor hood causes increased tension on the central slip