As some of you may know, I am actually an emergency medicine physician. Although I cannot attest to Chipper's injury by examining him, an evaluation of his comments and the replay demonstrate concerns for a tear of his medial meniscus and a lateral collateral ligament strain (LCL).
Chipper stated that he has pain in his lower knee, specifically the lower left side.
Chipper in an AP story:
"I've got a very distinct pain on the lower left side of my knee," he said. "I don't know what that means. Hopefully it's just a sprain. (We) just got to wait for the MRI."
The lower left portion of the left knee is directly over the medial meniscus. Tenderness that is reproducible only over this area is often associated with a tear of the meniscus. (Keep in mind, the below image is the right knee - reverse it for the left knee)
The meniscus functions to distribute your body weight across the knee joint. Without the meniscus present, the weight of your body would be unevenly applied to the bones in your legs (the femur and tibia). The meniscus also has a large area in the center of that has no direct blood supply (avascular). This presents a problem when there is an injury to the meniscus as the avascular areas tend not to heal.
It is not uncommon for the meniscus tear to occur along with injuries to the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL)-these three problems occurring together are known as the "unhappy triad," which is seen in sports such as football when the player is hit on the outside of the knee. However, this is not how Chipper hurt his knee...
Chipper landed on his left leg with his leg bent slightly and landing on the outside of his foot. This forced the entire weight of his body (plus the force of gravity from his jump) to land on the medial (inside) portion of his knee. This drove the end of his femur onto the medial meniscus - and also stretched the outside part of the knee (lateral collateral ligament - LCL)
So, what does this mean.....
The MRI tomorrow will likely identify any meniscal or ligament tear (although some meinscal tears are only visible on a endoscope. An example is below (the arrow is pointing at the torn medial meniscus of the left knee)
Treatment of a meniscus tear depends on several factors including the type of tear, the activity level of the patient, and the response to simple treatment measures. If a non-operative approach is chosen, he is looking at 4-6 weeks MINIMUM of rest/elevation and brace with physical therapy to follow. Injectible steroids ("cortisone shot") has been used but is only temporary at improving the pain - and likely can lead to worse damage to the meniscus.
If the non-surigcal option is chosen, keep in mind that some studies state that as many as 1/3 (33%) will require surgery due to lack of improvement via a conservative ("rest") approach.
When surgical treatment of a meniscus tear is required, the usual treatment is to trim the torn portion of meniscus, a procedure called a meniscectomy. Meniscus repair and meniscal transplantation are also surgical treatment options.
I hope I'm wrong, but don't expect Chipper back this year if the above is correct....