What is a sprain?
Practically everyone at one time or another has suffered a “sprain,” but while it is a common problem, most people do not understand exactly what it is.
The casual use of the word “sprain' adds to the confusion. Additionally, because the word is often incorrectly used, the severity and long-term consequences of these injuries are often minimized. If you've been unlucky enough to be injured in a car accident, you may hear the opposing insurance company say things like “it's just a sprain” or “just a soft tissue injury” it's not a serious injury. You may have also heard someone say these injuries heal by themselves rather quickly with no consequences.
To make a sprain injury more understandable, let's take a look at what a sprain actually is from a medical standpoint.
If you were to search on the internet the term “sprain” you will likely see this definition:
To sprain is to wrench or twist the ligaments of (an ankle, wrist, or other joint) violently so as to cause pain and swelling but not dislocation.
A sprain is the result of a wrench or twist of the ligaments of a joint.
This definition is incomplete. It does show that a sprain has a traumatic cause, which is true and it also states that it is an injury to a ligament, also true. What it doesn't describe is the actual medical, anatomical injury and that is very important in understanding this type of "soft tissue" injury.
Compare the above definition with the definition from the American Academy of Orthopedic Surgeons.1
A sprain is a stretch and/or tear of a ligament, a strong band of connective tissue that connect the end of one bone with another. Ligaments stabilize and support the body's joints. For example, ligaments in the knee connect the thighbone with the shinbone, enabling people to walk and run.
… A sprained knee can be the result of a sudden twist, and a wrist sprain can occur when falling on an outstretched hand.
Sprains are classified by severity:
Grade 1 sprain (mild): Slight stretching and some damage to the fibers (fibrils) of the ligament.
Grade 2 sprain (moderate): Partial tearing of the ligament. There is abnormal looseness (laxity) in the joint when it is moved in certain ways.
Grade 3 sprain (severe): Complete tear of the ligament. This causes significant instability and makes the joint nonfunctional.
So as you can see the more precise definition is a traumatic jerking or twist of a joint that results in “overstretching” of a ligament that causes damage, tearing of the fibers of the ligament. The severity of the sprain depends on how many fibers are torn. The reason this is important is because, especially in a medical-legal scenario, automobile insurance adjusters often claim a “sprain” in the spine is just an “injured” or “damaged” ligament and not an actual “torn” ligament. They classify this as only a "soft tissue injury."
You now know the truth, that a sprain is in fact a “torn” ligament to some degree. A Grade 1 sprain basically heals with little treatment over a period of weeks and leads to no discernible instability. A Grade 2 takes much longer to heal, months in fact, and NEVER returns to the same strength or elasticity as before because enough fibers have been torn to permanently affect the function of the ligament. It is a serious injury. A Grade 3 sprain is a very serious injury that involves a complete tear of the ligament and the joint is rendered totally nonfunctional and requires surgical repair.
Why are sprains serious?
Remember the function of a ligament is to hold a joint together. If the ligament loses its strength and elasticity it cannot properly hold the joint together. It's similar to the elastic in your socks; once its stretched too far, your socks will never stay up. When this happens, the joint malfunctions and osteoarthritis sets in within 5 years. In the spine it is especially problematic because excessive motion of the vertebral bones in the spine can lead to damage to nerves. If the instability is severe enough, it is classified as a very high degree of permanent impairment.
How do I know what Grade of sprain I have?
If you twist an ankle, and you experience only mild pain on walking and there is only slight swelling and no bruising in the area in the next 24 hours, you have a Grade 1 sprain. Let's say in the same injury you have difficulty walking and notice more swelling that obscures part of your ankle bone and you notice bruising in the area within 24 hours, you likely have a Grade 2 sprain. A Grade 3 sprain will be very painful, enough to totally prevent walking and the ankle may seem very loose and or make popping or cracking noises. Swelling will be severe and much bruising will be seen.
Spraining ligaments in your spine requires a high amount of stress on the ligaments. Car accidents and high intensity sports injuries are the most common causes. Because the ligaments are deep, you will not see swelling or bruising. An MRI can sometimes show larger tears in a spinal ligament, but not always. Additionally, an MRI is a static test, meaning the patient is lying still and not moving so you have no idea if any function is altered. You cannot see joint laxity or instability on a static MRI.
The best method for determining ligament damage in the spine is not by “seeing” the actual damaged ligaments, but by seeing the evidence of abnormal function due to ligament tearing.2 Remember a Grade 2 or 3 ligament sprain will allow for excessive movement in the joints. This can be viewed on motion or stress x-rays. In the spine x-rays are taken from the side in the neutral position, then with head flexed forward and again with the head extended backward for the neck or bending forward and back at the waist for the lower back. The spinal bones are then analyzed as they move to see if excessive motion exists. The amount of excess movement is measured and compared to a normal value. Bones that move too far are due to ligaments being “torn” to some degree and unable to hold the bones together properly. A Grade 2 sprain will show up as unstable motion on a bending x-ray, a Grade I will not. A Grade 3 would show extreme instability, enough to require surgery immediately. Grade 1 sprains often have very mild symptoms, so these victims often do not seek medical attention. Grade 2 sprains occur in around half of rear impact car accident cases, while Grade 3's are not nearly as common.
To recap, a sprain is a traumatic injury to a ligament in which the ligament is overly stretched. The severity of the sprain depends on how much of the ligament fibers are torn. A Grade 1 sprain is an overstretching with very little tearing, a Grade 2 is a partial tearing of the ligament and causes instability of the joint. A Grade 3 is a complete tear that results in total loss of joint integrity and requires surgery. Grade 2 & 3 sprains are common and serious injuries after a car accident that can be documented on “stress x-rays.”
American Academy of Orthopedic Surgeons http://orthoinfo.aaos.org/topic.cfm?topic=a00111
Brownstein SP, Jefferey Cronk DC, Joseph Cioffi BA. Evaluation of Spinal Ligamentous Injuries using Computerized X-ray Interpretation. Orthop Rheumatol Open Access J. 2015;1(1): 555551. DOI: 10.19080/OROAJ.2015.01.555551