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Hand Injuries Not to Miss

Author(s): Paul Auerbach
Posted: June 10, 2012

Hand injuries are common in outdoor enthusiasts. Some of these injuries are easy to diagnose, and others are more difficult, usually because the signs and symptoms are subtle or because the examiner is inexperienced. Emergency physicians, such as me, need to be hyper-vigilant in order to avoid making a mistake in diagnosis. In the field, when there are environmental stresses, poor lighting, noise, and perhaps even danger, it is even more difficult to make the diagnosis. 

A recent article in the European Journal of Emergency Medicine points out “Four hand injuries not to miss: avoiding pitfalls in the emergency department (18:186-191, 2011). Dr. Philip Yoong and his colleagues discuss ulnar collateral ligament of the thumb injury, Bennett’s fracture at the base of the thumb metacarpal bone, the volar plate avulsion fracture that occurs to the middle phalangeal bone of a finger, and avulsion of the flexor digitorum profundus tendon. Let’s consider practical field aspects of each of these in turn. Remember that these are all injuries that will eventually be referred to a hand specialist, so the point is to suspect these injuries so that they do not remain undiagnosed and under-treated.

The thumb has three bones: the metacarpal (closest to the wrist) and two phalanges. The metacarpophalangeal (MCP) joint is between the metacarpal bone and the closest phalanx. It is stabilized from side-to-side motion by two ligaments­­—the radial collateral ligament (lateral, or outside: on the side of the radius bone) and ulnar collateral ligament (medial, or inside: on the side of the ulna bone). Injury to the ulnar collateral ligament occurs then there is a force applied that pulls the thumb away from the hand—like hyperextending a hitchhiking motion. This might happen by falling forcefully while holding a ski pole. The term “Gamekeeper’s thumb” describes a chronic ulnar collateral ligament injury caused by the force created by Scottish gamekeepers who broke the necks of rabbits between the thumb and index finger. How does one make the diagnosis? Although this may be difficult because the examination is limited by pain, when accompanied by the appropriate history, one notes that stressing the thumb away from the hand at the MCP joint causes much more motion on the injured than uninjured side. Depending on whether or not the tear is partial or complete, the victim may be treated with immobilization alone or require surgical repair. In the field, this injury should be immobilized and the victim brought to a hand surgeon as soon as is practical.

A Bennett’s fracture is a break in the base of the thumb metacarpal bone. On X-ray, one sees an angled break in the bone that extends into the joint between the metacarpal bone and the trapezium bone, which is a bone in the wrist. If there has been much displacement of the thumb metacarpal bone at the fracture site, then the joint may become unstable, leading later to osteoarthritis with pain and stiffness. Thus, this fracture is best treated with surgery to achieve proper alignment and fixation for healing. How does one make the diagnosis? Any person with a history of injury to the hand who has pain and swelling of the base of the thumb might have this fracture, so the thumb should be properly immobilized and the the victim brought to an emergency facility for X-rays as soon as is practical.

There are three bones that comprise a finger: proximal (close in), middle, and distal (furthest out) phalanges. A volar plate avulsion describes a situation where the joint between the proximal and middle phalanges, known as the proximal interphalangeal (PIP) joint is injured by a hyperextension motion. In this process, a fibrous structure (volar plate) that connects the palm side of the proximal and middle phalanges across the PIP joint is ripped loose to a lesser or greater degree. Depending on the degree of injury, which is determined by examination and x-ray, surgery might be necessary to achieve proper alignment and allow healing. How does one make the diagnosis? With the history of a hyperextension injury, the victim often shows pain on the underside of the PIP joint, swelling, reduced range of motion, and perhaps bruising. If a dislocation at the PIP occurred and was put back into place, this is indicative of the type of injury that would be accompanied by a volar plate disruption. In the field, the joint should be properly splinted and the victim brought to a hand surgeon or emergency department as soon as is practical.

Finally, there is injury to the flexor digitorum profundus tendon. This is the tendon that creates flexion (downward bending) of the finger at the furthest joint (distal interphalangeal [DIP] joint). The injury is created by a force that pulls the tendon (and sometimes some bone with it) off its insertion (attachment) to the distal phalanx. After this occurs, the finger can no longer be flexed. How does one make the diagnosis? The finger may be swollen at the DIP joint and beyond to the fingertip, painful at this location, and perhaps bruised. To diagnose that the tendon doesn’t work, hold the PIP joint straight and ask the victim to try to flex the DIP joint. In the field, the finger and DIP joint should be splinted in a position of function. Prompt referral to a hand surgeon is essential, because if this injury is not repaired with surgery within 7 to 10 days, primary repair may not be possible. This would mean that any further improvement would only happen with more complicated surgery, which is less likely to achieve 100 percent return of function.

Reprinted with permission by the Author from Healthline.com

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