Wrist Injuries


 

Considerations in treating both common and complex injuries

By L.T. Donovan, DO

From Minnesota Physician
From Volume XXVII, No. 7, October 2013

Wrist injuries are common conditions seen by hand and orthopedic surgeons. They can vary from a simple non-displaced torus fracture of the distal radius in a skeletally immature patient to a complex dislocation of the wrist.

The mechanism of injury can be helpful in diagnosing patients who have sustained a wrist injury. It is important to examine above and below the so-called “zone of injury.” In a complex system such as the forearm and wrist, it is common to see an associated bone or joint injury. In addition, a thorough neurovascular examination should be performed, especially in a
high-energy trauma situation, so as not to miss an associated nerve or vascular injury.

Obtaining radiographs
After performing a standard physical examination, it is critical for the physician to obtain adequate radiographs to evaluate the injury pattern. When a patient is first examined, a “shotgun” approach is often used to evaluate the extent of the injury. When a patient complains of wrist and forearm pain following an injury, it might be tempting to obtain a forearm radiograph so that the entire forearm can be evaluated rather than obtaining separate joint specific radiographs. By taking this approach, however, one loses the ability to visualize the specific area in question. One problematic area we see on a regular basis is difficulty in obtaining a true lateral radiograph of the wrist. In those situations, a cross-table lateral radiograph usually is sufficient.

After obtaining the appropriate radiographs, we take a systematic approach to interpreting them. My recommendation is to look away from the area of the suspected injury first. If one looks directly at the area of injury and focuses on the “obvious” fracture, then one often tends to overlook other subtleties, such as a ligament injury resulting in a diastasis on the X-ray.

In a distal radius fracture, we look for certain characteristics, not only to identify a fracture, but also to analyze how well the fracture is aligned and what the tendency is for that fracture to stay reduced. I often refer to this as the “gestalt” of the fracture. Sometimes, just looking at the fracture pattern can provide a sense of whether or not the
fracture will be stable.

On the PA (posteroanterior) view, we look at the height of the articular surface of the radius in relation to the ulna. In most cases, the radius and the ulna are at the same level. In cases of significant displacement, the radius will be shortened. On the lateral projection,
the articular surface of the distal radius should be in a neutral alignment. With an increasing amount of angulation (usually apex volar), one can see a corresponding decrease in wrist flexion. The degree of dorsal displacement is also significant not only in regard to the fracture pattern, but also because of the possibility of developing post-traumatic carpal tunnel syndrome.

Determining treatment
When deciding what type of treatment to recommend, a physician must consider several factors, including the patient’s age, health, physical demands, and overall expectations. Older patients are usually more wary of surgical intervention, as are those from certain cultural groups. Younger, more physically demanding patients are usually not very tolerant of a wrist deformity and are anxious about trying to get back as much normal function as possible.

Fortunately, a relatively new technology for the operative treatment of wrist fractures is available. Around 2000, a new internal fixation plate was released for general use in treating wrist fractures. The low-profile plate is of a special anatomic design that hugs the volar surface of the distal radius. We often refer to this as a volar locking plate. It enables the operating surgeon either to insert the screws in a standard fashion where the tip of the screw
engages the opposite (dorsal) cortex, or to use a special locking mechanism in which the head of the screw has separate threads that allow it to be “locked” into the plate, preventing the screw from backing out. These locking screws are placed below the subchondral surface of the dorsal radius and, in essence, function as a scaffold to hold the radius out to length. This allows the patient to start moving the wrist in about one week.

With the ever-expanding goal of improving patient care and incorporating the need for a less invasive technique that can combine locking technology with standard fixation techniques, a new design has recently been approved by the FDA for fixation of wrist fractures. The Conventus DRS system allows for a similar degree of stability of fixation for a wrist fracture while requiring less soft tissue exposure to implant the device and simultaneously allowing early range of motion of the wrist.

When comparing the results of nonoperative and operative treatments, as long as the same parameters are followed concerning the adequacy of the reduction, the overall results one year
from the time of the fracture are about the same.

In cases of a distal radius fracture, the radiographs need to be evaluated carefully so as not to miss any associated injuries, such as a scaphoid fracture or a tear of the scapholunate ligament. In scrutinizing the radiograph, we look for a widening of the scapholunate interval
beyond 3 mm. In addition, on the lateral projection, the lunate should be well visualized to determine whether there is any rotation (a volar or dorsal tilt of the lunate).

There is no uniform consensus on how an acute scapholunate injury should be treated. This ligament is extremely small but very strong. Most often, it is repaired either directly (open technique) or by a closed reduction and placement of several pins across the scapholunate joint (temporarily) and immobilized for an extended period of time.

The long-term problem with a scapholunate ligament injury is the development of post-traumatic arthritis of the wrist. This leads to a scapholunate advanced collapse (SLAC) wrist. The treatment of SLAC wrist varies, and these operations are considered to be salvagetype procedures that involve some degree of a fusion, resulting in a significant loss of motion of the wrist.

Healing scaphoid fractures
A fracture of the scaphoid remains a frustrating condition for a hand surgeon. The scaphoid is one of the most difficult bones in the body to heal due to its poor vascular supply. This is because it is essentially covered by articular cartilage. In the past, almost all scaphoid fractures were treated with cast immobilization. We are moving more and more toward operative stabilization today, due to the fact that the operative procedure has become more reproducible, requires less time of immobilization, and results in better healing rates overall.

The problematic area of scaphoid injuries involves nonunion, where the scaphoid has not healed due to a limited blood supply. The treatment can vary from a bone graft only (Russe graft),
without any internal fixation but with prolonged cast immobilization, to a super-sophisticated free-graft transfer from the knee, which requires a vascular anastomosis to a local vessel. The primary problem with an untreated scaphoid nonunion is that there is an extremely high rate of developing posttraumatic arthritis, a scaphoid nonunion advanced collapse (SNAC) wrist.

A dislocation of the wrist usually includes a dislocation of the lunate. Typically, the lunate is “extruded” volarly, with a significant degree of trauma. The treatment involves an open reduction of the perilunate dislocation and repair of the ligaments, often requiring a volar and dorsal approach. The carpal bones are usually held in a reduced position with multiple pins, and the overall result is a significant loss of wrist motion with a limited outcome.

Injuries can affect function, earning power
Injuries that involve the wrist require an understanding of the anatomy and the complexities of the joint itself. One must recognize not only the more common injuries but also the less common, but potentially devastating, associated injuries. These can result in a significant
loss of function and impairment of the wrist, affecting not only the patient’s lifestyle, but also his or her economic ability.

L.T. Donovan, DO, of Summit Orthopedics,
practices at several locations, including the
Apple Valley Medical Center