Wrist fractures involving the radius bone of the forearm has a well-known complication associated with it. And that is rupture of the extensor pollicis longus (EPL) tendon of the thumb. This tendon helps move both the tip of the thumb and the wrist, so damage to it can impair function of the hand.
There are reports of how often this tendon rupture occurs after radial wrist fractures. The incidence ranges between 0.3 and two per cent. In this study, surgeons from one institution (Brigham and Women’s Hospital in Boston) report a five per cent incidence. This is much higher than previously thought and bears mention as well as closer study.
The authors devised a three-step process to identify patients for the study. First, they looked through their database (information collected on all patients at their hospital) and found all patients within a three-year period of time who had a radial fracture.
In particular, they were looking for nondisplaced radial fractures. Nondisplaced means the bones did not separate or shift after the break occurred. The reason for finding nondisplaced radial fractures is because extensor pollicis longus (EPL) rupture is most likely to happen with this type of fracture. We will explain the connection between nondisplaced wrist fractures and EPL ruptures in just a moment.
Once they identified patients for inclusion in the study, then they looked at everyone’s X-rays (step two). Four separate physicians independent of each other reviewed the films. They were looking at the angle and height of the radial bone as well as alignment of the wrist joint to make sure no one in the study had a displaced fracture.
In the third and final step, they reviewed the medical records of each person with a nondisplaced radial fracture. They were looking for those patients who had a documented EPL rupture. They found three of the total 61 patients who had an EPL rupture. This is a five per cent incidence rate. All EPL ruptures occurred approximately six weeks after the fracture. All were in women ranging in ages from 18 to 88.
Now, what is the significance of an EPL tendon rupture after a nondisplaced radial fracture? We did promise to explain this. When the force that breaks a bone is not enough to rip or tear the soft tissues around the bone, complications like the tendon rupture can occur later. This is because the tendon is held tightly against the bone. The fracture results in swelling, bleeding into the area, and the formation of a bone callus as healing takes place.
All of these events decrease the space around the tendon and put pressure on the tendon. The EPL tendon in particular doesn’t have a very good blood supply to its own tendon sheath (outer protective covering). Anything that disrupts this area can reduce blood flow and nutrition causing avascular necrosis. Avascular necrosis means death of the tissue due to loss of blood. The end result is rupture of the tendon.
Knowing the incidence of EPL rupture after nondisplaced radial (wrist) fractures may be higher than previously thought suggests the need for surgeons to watch closely for this complication. Usually a nondisplaced wrist fracture is immobilized in a splint or cast. The risk of a tendon rupture isn’t in the forefront of the surgeon’s mind. This report points out the need to be aware of this potential problem.