Mallet Finger in a Teen Athlete: A Case Study

Mark S. Granick, MD

Disclosures

February 08, 2010

Introduction

Mallet finger is one of the most common closed tendon injuries of the hand. It occurs when the distal phalanx is held in extension while a flexion force is applied across the joint. The trauma results in the avulsion of the extensor tendon from the point of attachment to the distal phalanx (Figure 1). A segment of the distal phalanx, which comprises the distal portion of distal interphalangeal (DIP) joint, may break off along with the tendon (Figure 2). If not treated, mallet finger leaves a deformity with the DIP in permanent flexion. These injuries require radiologic evaluation. Radiographs will demonstrate whether the injury involves a concomitant fracture of the dorsal base of the distal phalanx. The extent of injury dictates the most appropriate treatment (Figure 3). Simple tendon avulsions are treated with prolonged continuous extension splinting of the DIP for 6-8 weeks. Small associated bony avulsions are similarly treated. If the joint involvement is greater than 40% of the joint surface, or if there is a DIP fracture dislocation, then surgery is warranted.

Figure 1. Tendon avulsion that occurs with common mallet finger injury. From eOrthopod (www.eorthopod.com).

Figure 2. This tendon avulsion also has a bone fragment involving the distal interphalangeal (DIP) joint. From 3-Point Products (http://www.3pointproducts.com/HomePage/)

Figure 3. The spectrum of injury seen with mallet deformity. Left. Tendon avulsion. Right. Bony fracture-avulsion. From The Jungbauer Family Website. (http://jungbauer.org)

An Athlete With Mallet Finger

Patient Presentation and History

A 16-year-old boy injured his dominant long finger in football practice. He did not recall exactly how the injury occurred. He was seen in an emergency department and had a splint on his finger. The patient had no other significant medical history.

Physical Examination

The general examination was normal. The right and left hands were normal with the exception of the injured finger. When the splint was removed, the DIP joint was unstable with a volar dislocation. Radiographic analysis showed an avulsion fracture of approximately 60% of the distal joint surface. The patient’s epiphyses are closed (Figure 4).

Figure 4. Anteroposterior and lateral radiographic views. The right middle-finger distal interphalangeal joint has a fracture involving approximately 60% of the distal joint surface. The joint was unstable and the radiographs were obtained with a finger splint in place. Image courtesy of Mark S. Granick, MD

Diagnosis

This patient has an unstable fracture dislocation involving more than 40% of the DIP joint surface; therefore, this injury requires operative repair.

Management Plan

Most mallet finger injuries can be closed-reduced and fixed by percutaneous placement of K-wires. There are a variety of techniques to capture the avulsed fragment and fix it solidly to the distal phalanx. If closed reduction cannot be achieved, an open technique is recommended. Many techniques are also available to open-reduce and internally fixate the fracture. In this case, the fracture could be closed-reduced. A percutaneous #28 K-wire was used to capture the fragment and fix it to the distal phalanx. Proper reduction and fixation were confirmed with intraoperative fluoroscopy. A #35 K-wire was then placed longitudinally from the fingertip through the distal and middle phalanges to fix the DIP in place during the healing of the fracture. A radiograph obtained at postoperative week 4 (Figure 5) demonstrates the position of the K-wires and the reduction and healing of the fracture. The small K-wire was removed at that time, and the DIP-blocking K-wire was maintained for another 2 weeks. After that, additional splinting was applied for 2 more weeks.

Figure 5. Anteroposterior radiographic view of finger after 4 weeks. The longitudinal K-wire is blocking the distal interphalangeal joint from flexion to protect the repair. The smaller oblique K-wire is placed through the bone fragment, fixing it to the distal fragment. The fracture appears to be healed in good position. Image courtesy of Mark S. Granick, MD

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