Orthopaedic Hand Trauma CH35

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SECTION 3  | Tendon Injuries

patients will resist flexion of the entire finger as a result of pain, which can obscure the diagnosis. In the acute setting, an FDP avulsion can be misdiagnosed as a “sprained finger.” It is essential that the clinician isolates DIP and proximal interphalangeal (PIP) joint motion to pre- vent a delay in diagnosis. In some cases, the physician may be able to palpate the flexor tendon retracted proximally along the flexor sheath. ■ ■ Imaging —Anteroposterior, lateral, and oblique radiographs should be obtained to assess for avulsion fractures or articular injuries. A bony avulsion fragment of the volar lip of the distal phalanx articular surface may be present ( Figure 35.4 ). Approximately 50% of FDP avulsions are associated with an osseous fragment. If the injury is purely tendinous, the only radiographic finding will be slight extension of the DIP in resting position. MRI can be used if the diagnosis is unclear or the location of the retracted tendon is unknown. ■ ■ Differential diagnosis ● ● Anterior interosseous nerve paralysis ● ● Trigger finger ● ● Swan neck deformity ■ ■ Classification —The Leddy and Packer classification system is used most commonly ( Table 35.1 ). Type I, II, and III injuries are most common. ● ● In type I injuries, there is complete tendon rupture with retraction into the palm. The tendon is tethered in the palm by the lumbrical origin and both the vinculum longus profundus (VLP) and brevis profundus (VBP) are ruptured. As a result, there is significant vas- cular compromise, and expedited surgical intervention is required within 7 to 10 days of the injury.

Figure 35.4  Lateral radiograph showing Leddy and Packer type III FDP avulsion. FDP, flexor digitorum profundus.