Minnesota Vikings quarterback Sam Bradford has been dealing with a left knee injury for the past 4 weeks. Bradford had his anterior cruciate ligament torn and subsequently repaired by Dr. James Andrews both in 2013 and 2014, both on the left knee. Bradford has underwent multiple MRIs based on reports, both of which said that there was no structural damage, but there is a significant bone bruise that he is dealing with. Additionally there is a very good chance that Bradford is dealing with a great deal of arthritis in this left knee (likely both), as osteoarthritis is a commonly recognized complication of ACL tearing, secondary to the amount of ‘wear and tear’ Bradford has endured over his playing career.
What is a bone bruise? A bone bruise, sometimes referred to as a bone contusion, is a microfracture of the internal structures of the bone, but no actual break in the outer bone. They are usually associated with traumatic injuries, but cannot be seen with the naked eye or with x-ray, as they can only be visualized with the help of an MRI. These injuries often fall into two classifications either ‘sub-periosteal hematomas’ or ‘occult bone lesions.’ Regardless of the type, bone bruises are very painful, often taking several weeks, sometimes months, to resolve spontaneously without much intervention. Technically you can get a bone bruise in any major joint of the body, including the hip, ankle, elbow, foot and spine, but the knee is usually the most common. Since these can only be confirmed with MRI, many of these bone bruises often go unnoticed.
How do bone bruises occur? Bone bruises often occur when there is direct trauma to the bone, often a result of a forceful twisting injury. Bone bruises are typically located on the posterior portion of the lateral tibial plateau and the lateral femoral condyle (see Image 2). The location of this bone bruise is most consistent with a valgus, meaning outward force, mechanism of injury. This is basically the posterior lateral portion of your knee; so if you were to grab the back outside part of your knee, this is the location we are talking about, and the most common location of a bone bruise. Although the exact location of Bradford’s has not been revealed. Bone bruises are often associated with anterior cruciate ligament injuries, although in this situation Bradford did not tear his anterior cruciate ligament for a third time.
Think of accidentally running into something and getting a bruise on your arm or leg. This is an example of a soft tissue bruise that typically resolves in about 1-2 weeks. Unfortunately, bruises inside of the bone take a much longer time to recover; multiple studies have shown that about 88-100% of the time it takes between 5 and 16 months for bone bruises to fully heal. In addition to the microfractures to the internal structures of the actual bone, there can be a large amount of bleeding under the layer of tissue that essentially covers the bone, as you can see in the Image 3 below. On an MRI there are areas of increased signaling, meaning that the area is brighter and whiter, secondary to an increase of fluid (blood) in the damaged bone area.
It appears that Bradford sustained this initial injury in the Vikings’ September 11 Week 1 Monday Night Football win over the Saints. After taking nearly 4 weeks off, Bradford tried to give it a go again on October 9 versus the Chicago Bears, but looked visibly uncomfortable, even falling down in pain without taking much pressure. There were times where he looked as if he was not able to step into his throws, possibly secondary to the pain in his left knee. Recent report by NFL Network’s Ian Rapoport stated that Bradford underwent Regenokine treatments in New York to try to help stimulate healing in Bradford’s knee. It remains to be seen how effective these treatments will be, and when Bradford will be able to return to play pain-free.