The wrist is made up of two rows of small bones. One row of bones articulate (move) against the two bones of the forearm. The second row lines up with the base of the fingers and thumb. A fracture of any of the carpal (wrist) bones in these two rows can create problems -- especially if the bone doesn't heal. That's called a fracture nonunion.
In this Canadian study, a surgeon from the University of Toronto Hand Program reviewed the charts of 96 patients with nonunion fractures of the scaphoid bone. The scaphoid is the most common carpal bone to break. It is located on the thumbside of the wrist next to the radius (larger of the two forearm bones).
The goal of this study was to find out why this particular bone fails to heal. Is there something about these particular patients that creates a nonhealing response? Does their age or sex (male versus female) make a difference?
Did the medical care they received fail to treat the problem correctly? Having a better idea of how and why scaphoid fractures result in a nonunion may help surgeons manage these cases more effectively in the future.
Other studies have reported a nonunion rate as high as 40 per cent. This high rate occurs when the patients were not diagnosed or treated right away. To give you an idea how that 40 per cent rate compares, there's a three per cent rate of nonunion when the problem is diagnosed and treated within 30 days of the injury. This finding supports the idea that timing of evaluation and treatment might be an important factor.
Other studies have also looked at the ability of X-rays and other imaging studies to accurately diagnose scaphoid fractures. In fact, the high rate of false negatives (X-rays don't show the fracture when it's really there) contributes to the problem. The injury isn't treated at all and the result can be a nonunion.
But there are also cases where the wrist is put in a splint or cast to immobilize it and the fracture still doesn't heal. So, the question is: why don't scaphoid fractures heal? As this Canadian hand surgeon found out, there are two groups of important factors.
The first is biologic factors. The location and severity of the fracture make a difference. Fractures closer to the radial bone are more likely to result in a nonunion. The blood supply to this area is also very fragile so a fracture that disrupts blood flow can also be a significant reason why the bone doesn't heal.
The second major reason why scaphoid fractures don't heal is referred to as clinical factors. Patients may not have painful symptoms so they don't go to a physician for diagnosis and treatment. Or if they are diagnosed, they may not follow the recommendation to immobilize the wrist for four to six weeks. And, of course, as we already mentioned -- delaying treatment by four weeks or more is a definite risk factor.
What about other patient characteristics like age or sex (male or female)? As it turned out in this group of patients, the majority (89 per cent) of the fractures were in young men (ages 25 to 29). Some didn't even know they had injured their wrists.
One-third of the group did not seek medical attention. They either didn't think it was much of a problem or the painful symptoms got better without treatment. Pressure to return to sports participation in this age group may have led some to minimize their symptoms.
The authors concluded it's no wonder diagnosis and treatment for scaphoid wrist fractures go undetected and/or untreated. With such a wide variation in symptoms, a high rate of false negative X-rays, and fractures that occur without a known injury, it's easy to see how this could happen.
What can be done to change this clinical picture? Education of primary care physicians, emergency staff, Physical Therapists, athletic trainers, and other sports personnel may help. Health care professionals working with sports athletes need to know that scaphoid wrist fractures can be painless and that they have a tendency toward nonunion.
Better evaluation and closer monitoring of wrist injuries and painful wrists (without known trauma) may result in better outcomes with fewer cases of scaphoid nonunion. The results of this study highlight patient characteristics, biologic factors, and clinical factors that might be red flags to help guide patients to an earlier diagnosis and more effective treatment.
Reference: King Wong, MB BCh, and Herbert P. von Schroeder, MD. Delays and Poor Management of Scaphoid Fractures: Factors Contributing to Nonunion. In The Journal of Hand Surgery. September 2011. Vol. 36A. No. 9. Pp. 1471-1474.