What's the difference between a sprain and a strain? I've been reading a lot about the Orioles' Jeffrey Hammonds' knee sprain and the possibility of ligament damage. But when my 15-year-old daughter had a strained knee from running track, the doctors seemed more concerned about her bones.
We suspect a lot of people are confused about the two words, and to make sure we could answer your question correctly, we verified our information in a sports medicine text.
The answer to your question has two parts: As you implied, a strain is not the same thing as a sprain, and there are important differences between adults on the one hand and children and adolescents on the other in terms of how these injuries can affect them.
A sprain is an injury to a ligament. Ligaments are fibrous bands that help stabilize various joints in the body, and they do so by connecting two bones. For example, there are four ligaments providing stability to the knee, and a severe injury to one of them could involve a complete tear of the ligament with resulting loss of stability. Jeffrey Hammonds sustained such an injury to his anterior cruciated ligament in the past and did require surgery to repair it.
A strain, on the other hand, involves an injury to a musculotendinous unit. Muscles attach to bones via tendons, so a strain could involve injury to the muscle itself, to the tendon, to the junction of the muscle and tendon or to the junction of the tendon and bone.
While children are growing, a process that continues until the end of complete physical maturation, their bones are not all one piece. Once puberty ceases, all the growth, tendons and ligaments may be relatively stronger than the bone to which they attach. Therefore, when an injury occurs that places a stretching force on a ligament or tendon, it may be the bone, rather than the tendon or ligament, that gives way.
In other words, the ligament or tendon partially or completely rips a piece of bone away from the rest of the bone. This is referred to as an avulsion fracture. It is possible that this can happen in adults, but it is much more likely in children and adolescents. Because these avulsion fractures occur near the centers of bone growth, an improperly treated or undetected fracture can result in damage to the growth center and improper growth of the affected bone.
We suspect that this was the concern with your daughter's injury and that is why clinicians who care for children and adolescents worry as much about the possibility of bone as ligament or tendon damages.
Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.
Pub Date: 10/08/96