Anthony McDonald and His Hyper Extended Knee

Inside Linebacker Anthony McDonald (Jr.) was recently upgraded from “Doubtful” to “Questionable.”

Carlo Calabrese (So.) has been penciled in on the depth chart as the starter.

Hyper extensions of the elbow and knee do not even sound pleasant. To get a better understanding of Anthony’s injury, SAS has dialed up our resident Physical Therapist Alex Brenner to give us the low down and prognosis.

Alex has over 14 years of physical therapy experience in the military, private clinics and the U.S. Public Health Service. He is rated as a DPT, Doctor of Physical Therapy.

Background


The knee joint is classified as a hinge joint much like the hinge of a door in that the primary motions are to flex and extend. There is little side to side and rotational motion that occurs in the knee joint. The knee normal range of motion is typically agreed upon to be 140 degrees of flexion and 10 degrees of hyper extension. Any motion past these values will put stress on the joint, cartilage and the ligaments that support them. The ligaments that are typically injured during a hyper extension injury are the collateral ligaments (those on the left and right side of the knee joint) and the anterior cruciate ligament (ACL). Naturally, the higher the force of the hyper extension the greater the chance of damage to these knee structures.

How does a hyper extension knee injury occur?

The knee does have about 10 degrees of normal hyper extension which is important for propulsion during running and jumping. The hyper extension injury in football typically occurs with contact when the athlete is either hit by a low block below or at the level of the knee joint forcing the knee joint past the normal 10 degrees of hyper extension. Another common mechanism of a hyper extension knee injury is when the athlete’s leg gets tangled in a pile up and forced into hyper extension.

Prevention

Proper bracing at the knee using a rigid knee brace with vertical stabilizers and extension stops can provide some protection but there is not a ton of research to support this.

Treatment

Unfortunately with ligament injuries (collaterals or the ACL) they do not heal quickly. Ligaments are poorly vascularized so they don’t get a ton of blood supply to help them heal. The results are they simply take much more time to heal. Treatment consists of rest, joint protection and general lower extremity strengthening to prevent muscle atrophy. Once he is cleared to start practicing again he will need some time to test the knee with sprinting and putting some stress on the hyper extension aspect of the knee joint motion. Unfortunately, we kick off with Purdue on Saturday and so I don’t think we will see a lot of action from Anthony as he recovers from this injury.

Conclusion

From what I can gather on the very limited information on Anthony’s knee, he sustained a mild to moderate hyper extension knee injury and has what I would guess a low grade sprain of the collateral ligaments and the ACL. I am confident that the ACL was not torn since we did not hear any bad news which typically accompanies that type of season ending injury. A low grade ligament sprain could take 3-4 weeks before he felt comfortable returning to competition. I suspect we will see limited action of him in Purdue and look for a full return for the Michigan game.

Thanks Alex. 

Good Luck Anthony, wish you the best on a speedy and full recovery.

Go IRISH ! Beat the Boilermakers.