AC, ACL: a tale of two ligaments

Monday, September 24, 2012

Like in real estate, injuries to the body are all about location, location, location. And that principle is best shown by Buffalo Bill’s C.J. Spiller and Darelle Revis of the New York Jets, who both sprained joints. Spiller will be back in a couple of weeks with his shoulder separation while Revis is done for the season after tearing an ACL in his knee. Both injuries are joint sprains but with totally treatment and outcome.

Some terms and anatomy:

  • Ligaments maintain the stability of a joint and a sprain defines a ligament that has been stretched or torn.
  • The anterior cruciate ligament (ACL) is one of four ligaments that hold the knee stable but it is a rock star for all the publicity. It prevents the tibia or shin bone from sliding forward in relation to the femur or thigh bone. Should the knee twist as it starts to straighten, the ACL can tear.
  • A shoulder separation actually describes an injury to the acromioclavicular (AC) joint, where the collarbone meets the shoulder blade. The joint increases rotation range of motion of the shoulder by acting as a gliding strut and pivoting the shoulder blade. Two ligaments hold it in position and if they are damaged or sprained, shoulder range of motion and power are affected. The joint is usually injured when a player falls directly on the point of the shoulder.
  • Generally, a first degree sprain means that ligament fibers are stretched but intact, second degree describes partial tearing of the ligament and third degree means that the ligament is completely torn.

When the ACL is torn, the quadriceps and hamstring muscles that move the knee shut down and immediately start to weaken, making the knee more unstable. Repairing or replacing the ACL is the only way to return an athlete to the playing field but it requires an operation and months of rehabilitation to allow the new ligament to heal, the knee to regain range of motion and the muscle to regain their strength. There is no quick return to play, no matter how strong the player or how dedicated to physical therapy. Nature can’t be rushed in making the ligament fibers heal solid.

Damage to the AC joint causes the muscles that surround the shoulder to shut down because of pain. That limits range of motion and that takes the player out of the game. But the difference is that once the pain is controlled, physical therapy can start immediately to return range of motion and increase strength. Surgery is usually not a first line treatment option and is considered only if arthritis and inflammation starts to affect the joint. Type I and II sprains can heal within a couple weeks, while a grade III sprain can take longer, with rehab lasting weeks to months.

ACL tears can be diagnosed by physical exam on the field with confirmation by MRI but the player knows almost immediately that something bad is happening in the knee. With the AC joint, there is more mystery, especially if the injury is initially hidden by a shoulder pad. Plain x-rays may be enough to make the diagnosis but when a pro athlete’s joint is involved, it’s almost automatic to get an MRI.

Two joints, two sprains, two different outcomes. C.J. Spiller is already talking about being back on the field in a couple of weeks. The reality of a lost year is still sinking in for Darelle Revis.

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