NFL Injuries

Dr. Morse breaks down the Kenneth Dixon surgery and impact

Photographer: Zach Bolinger/Icon Sportswire

Update: Unfortunately for Dixon, when the surgeons went into his knee to start repairing his meniscus, they must have determined that the severity of the tear was too much to just do a ‘clean out.’ This then translates to him requiring either a full removal of the entire meniscus, or at least removal of a large piece of the meniscus. The other possibility is that they had to sew a large piece of meniscus back to where it belonged. Either scenario, Dixon will miss approximately 4 to 6 months. Rest, rehabilitation, and anti-inflammatories. This will then likely put him out for the entire 2017 season, and his once bright career may be in jeopardy due to the fact that his knee may never be the same again. Unfortunate injury indeed.

The Baltimore Ravens announced today that running back Kenneth Dixon suffered a meniscal tear in his knee. Meniscal tears in the knee are arguably the most common knee injury, and orthopedists and sports medicine physicians see this injury on a daily basis. Think of the meniscus as a small pillow of cartilage in between the upper leg bone (femur) and the lower leg bone (tibia). This cartilage serves as a chondroprotective function or buffer to help provide some fluid to help the knee glide slowly and be able to plant the foot on all different surfaces and angles. Unfortunately, sometimes when the knee and foot are not in perfect alignment then a piece of that cartilage can get torn.

Meniscal injuries are classified by their pattern of tear, including a vertical longitudinal, oblique or flap tear, horizontal, radial (transverse) and complex. Of those, vertical and oblique tears are the most common, making up approximately 80% of them. With age the incidence of complex degenerative tears significantly increase in frequency. A complete or displaced vertical tear has a special term, called a bucket handle tear, due to the specific motion of the tear.

The best way I like to describe a meniscal tear is to think of the paper sheet that you sit on in a doctor’s office, now slightly tear the edge of that sheet so that it is still attached but flopped over. By still being attached, this tear can cause additional trauma because it is no longer even (parallel) with the rest of the meniscus. Now if this small piece of cartilage were to completely tear off, then you have this cartilage floating around in a fluid filled knee compartment creating small amounts of trauma, specifically because it’s not supposed to be there, causing more and more damage.

Unfortunately meniscal injuries are so common because all it takes is one wrong step in an awkward position to cause them. Stepping down from a one-foot step onto the ground, like trying to avoid a rock, hole, or someone else’s foot can cause the meniscus to tear. Thereby resulting in extreme pain, and usually associated with swelling.

Specifically for Kenneth we know that he suffered a meniscal injury based on reports, but we do not know the exact location of this tear, whether it is anterior or posterior, medial (meaning closer to the inner thigh), or lateral (closer to the outside of his leg). Depending on the location treatment and evaluation are usually different. Posterior meniscal tears are much more accurately diagnosed with an MRI, approaching approximately 100% accuracy. However, anterior meniscal tears diagnosed with MRI are less accurate, closer to about 70%, simply because of the angle and technique of imaging.

To further complicate this, the meniscus in general has a poor blood supply. So if the piece of cartilage that has torn off is large enough to get resewn back to its original location, you have to be careful about where in the knee this occurs. If the area has a very good blood supply, then resewing the cartilage back is usually a good idea and will work out well. However, if the care and reapplication of the cartilage is in a poorly vascularized area of the knee, then this sewing and replication will never hold, and will likely just cause more issues.

Ideally, we always want to have as much original cartilage in our knee as possible.  Unfortunately the human body does not regenerate knee cartilage, meaning whatever cartilage you were born with, that is the total amount you will have for the rest of your life. There is slow wear and tear of this cartilage throughout the years.

It is unclear exactly which type of procedure Dixon is going to undergo. There are basically two options: there is an arthroscopic clean out, where an orthopedic surgeon goes in and trim out the loose pieces of cartilage. This is the least invasive, and most likely to return quickly from, in approximately 4 to 6 weeks. The other surgical option for Dixon would be a meniscal repair, which involves repairing the torn part with suture. This surgery would take Dixon off the field for approximately 4 to 6 months. Hopefully, this is not the surgery the Dixon needs. There is really no way to know how much damage there is in the knee with 100% accuracy until the knee is being evaluated in the operating room. So the surgeon has to be decisive about how much to remove, and how they plan to fix the cartilage, in order to help the patient in the long run.  You can click the link below to see our 3D animations on meniscus tears:

Meniscus Tears 

Studies have shown that there are better outcomes if the cartilage is repaired versus resected, with lower incidence of degenerative change after five years. There is more rapidly degeneration (think arthritis) noted after a lateral meniscectomy as compared to a medial meniscectomy. Factors affecting the influence of future arthritis include amount of resection, type of resection, associated instability, overall weight-bearing alignment, body habitus, age, and activity level. It is important to know that functional results do not always correlate with radiographic findings. Just because the x-rays of the knee may not look very good, the patient’s knee may still feel and perform well without any pain. The good news is that meniscus repair is successful in approximately 80% of the cases. Healing rates increased to approximately 95% in the setting of a contaminate ACL reconstruction.

Dixon is already suspended for the first four games of the season. He may get lucky and that he may be able to return fresh off a suspension without missing any additional games if indeed it is just a minor meniscal tear that just needs a trim (clean out). However, if he needs to undergo a more extensive repair or partial removal of a large piece of cartilage, he could possibly miss the majority or even entire 2017 season.

This was written for the @TheFantasyDRS by Dr. Jesse Morse. I am a Board-Certified Family Medicine physician, and I am currently completing a Sports Medicine Fellowship at the University of South Florida in Tampa. If you have any questions or comments, you can contact me directly at @DrJesseMorse or visit my website at: www.DrJesseMorse.com. Keep an eye out for my next article!

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