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On the inner and outer sides of the elbow, thick ligaments (collateral ligaments) hold the elbow joint together. The ligament on the inside of the elbow is the ulnar collateral ligament (UCL). It goes from the inside of the humerus to the inside of the ulna and is exposed to extreme stresses as it secures the elbow during overhand throwing (Tommy John issues).
Several muscles, nerves, and tendons cross at the elbow. The muscles of the forearm and wrist begin at the elbow and are important stabilizers of the elbow during throwing. The ulnar nerve crosses behind the elbow. It controls the muscles of the hand and provides sensation to the small and ring fingers.
Why say all this? As stated in the beginning, you have to know that there is a lot of important structures converging and passing through the elbow area that can be damaged very easily without proper mechanics and prevention.
Elbow Stress
The technical word for the stress is “valgus”. Definition: a position in which a part of a limb is bent or twisted outward, away from the midline to an abnormal degree.
Throwing causes enormous valgus in the elbow and couple that with the fact that overhand throwing is not a natural movement for the body you can see why the elbow is vulnerable to injury just by throwing overhand.
There are two main stressors on the elbow when throwing. One,
the issues at the cocking-to-acceleration transition (picture 1).
Not natural and pretty self-evident in picture.
Secondly, elbow extension (picture 2). Most don’t realize this
stressor. The elbow takes on a mega amount of force at the
moment the arm begins deceleration with elbow extended out
in front. Without giving a big medical definition – its bone-on-
bone contact at high velocities and can lead to fractures and
other damage within the joint.
As you can see, overhand throwing places extremely high and
unnatural stresses on the elbow. In baseball, these high stresses
are repeated many times and can lead to serious overuse injury
not to mention if you have poor mechanics.
Causes
Mainly overuse and mechanics.
Unlike an injury that results from a fall or collision with another player, an overuse injury occurs gradually over time. Overuse injuries develop when an athletic movement is repeated often during single periods of play and when these periods of play (games, practices, etc) are so frequent that the body does not have enough time to rest and heal. This is compounded if the player’s mechanics are incorrect. Most elbow problems occur at the inside of the elbow because considerable force is concentrated over the inner elbow during throwing. On occasion, genetics are the issue.
Picture 1
Picture 2