What is Mike Trout's latest injury concern -- and what does it mean for his return?

Costovertebral dysfunction? Here's what you need to know about Mike Trout's injury. (1:28)

After Angels star Mike Trout was diagnosed with an unfamiliar back condition, Stephania Bell is here to explain what costovertebral dysfunction is. (1:28)

Los Angeles Angels superstar Mike Trout has vowed to return this season after it was revealed that he has a spinal condition that could affect him for the rest of his sure-fire Hall of Fame career.

"I'm appreciative of all the prayer requests," Trout said, "but my career is not over."

So what is the condition, exactly, and what does it mean for his 2022 season and beyond? ESPN's Stephania Bell answers the biggest questions surrounding the three-time American League MVP.

What is Mike Trout's injury?

Angels athletic trainer Mike Forstad told reporters Wednesday that Trout has a "costovertebral dysfunction at T5."

The first hint of the problem came when Trout exited a game early on July 12, reportedly due to back spasms. He was subsequently placed on the IL with what was termed rib cage inflammation.

The reality is that all three of these descriptors are interrelated.

Let's begin with the actual diagnosis of costovertebral dysfunction at T5. The "T" stands for thoracic which refers to the middle section of the spine. There are three primary regions within the spine with distinct articulating vertebrae: the neck (cervical spine) consisting of the top seven vertebrae, the low back (lumbar spine) consisting of the lower five vertebrae and the mid back (thoracic spine) consisting of the twelve vertebrae in the middle. Each vertebra is labeled by its position within its respective section in descending order from the head. For instance, in the thoracic spine, the vertebrae are labeled T1-T12 with T1 being the first vertebra just below the cervical spine and T12 being the last vertebra just before the lumbar spine.

T5, the level referenced in Trout's injury, is the fifth thoracic vertebra. For context, it is positioned at about the level of the upper part of the shoulder blades.

Compounding the anatomy in the thoracic spine, each vertebra interfaces or articulates with a rib. Those articulations form joints. The joints are very tiny yet they are similar in structure and function to any other joint in the body with cartilage covering the interfacing surfaces, capsule and ligaments around them to provide support and muscles in the area to control movement. The specific joint where a rib articulates with the body (main box-like portion) of the vertebra is called a costovertebral joint, "costo" for the rib and "vertebral" for the vertebra, and in the thoracic spine there is a joint at every level and on each side (for the left and right ribs).

In addition to movement properties, the costovertebral joint can be a source of pain if there is an injury. Like with other joints, trauma or overuse can result in localized pain and inflammation which can then trigger muscle spasms as a protective mechanism. Spasms are often the body's way of splinting a joint so as not to allow excess motion that could result in further injury; pain is a means of preventing that movement.

Trout has indicated he's not sure how or when the injury happened, which is not uncommon, particularly in the case of a repetitive motion or overuse situation. It may have been developing for some time but finally reached a point of provoking enough pain and spasm to limit his ability to perform baseball activity. Somehow he developed an injury at this T5 costovertebral joint that now, as a result of pain, (rib cage) inflammation and (back) spasms, is not permitting normal motion. All together, the situation represents a costovertebral dysfunction at T5 with associated rib cage inflammation and back spasms.

What does an injury like this mean for a baseball player? What parts of his game would it affect?

It has the potential to affect every aspect of his game, particularly when it is in the acute stage, as pain and inflammation will limit movement in every direction. Baseball is a largely rotational sport, however, and the rotation involved in swinging a bat, throwing a ball from the outfield (no matter which side is affected, since rotation creates movement on both sides of the spine) could be particularly problematic. Diving to make a play in the outfield or to slide into a base could also be impacted given the movement associated with either of those skills. Straight line running might be less of an issue, but it's worth noting that breathing creates rib motion, so in the acute phase running could also be affected.

What does it mean for this season?

Trout is undergoing the treatment one would expect for any joint-related injury. He has already received a cortisone injection to help target local inflammation, and he is resting from baseball. As the inflammation settles down, he will likely gradually increase his mobility and conditioning and do very specific exercises targeted at strengthening the smaller muscles of the spine and rib cage that help control movement at the joint.

Assuming he can perform those activities pain-free, he could gradually progress to baseball-specific activity, including light throwing and swinging of a bat with the ultimate goal of returning to competition. It's not possible to say how quickly and effectively he'll progress, and Forstad told reporters they were not at a point yet of making a decision regarding the rest of the season. For his part, Trout says he expects to play again this year and that certainly sounds within reason, presuming he can get his current symptoms under control.

What about for his career?

Trout was very clear the other day when he said, "My career isn't over." And he's right. This should not be a career-threatening injury, at least as it's been described thus far. But it may be -- just as with any other joint injury affecting an athlete -- that he is on a maintenance program going forward that incorporates exercises designed to reinforce the strength of the muscles in that area.

Could there be a future flare-up? Sure. And should that happen, the regimen would likely be very similar. It might even settle more quickly given the knowledge gained from this first episode. But there's also a chance he could go years without a flare-up. There are really no guarantees.

Is it related to the other injuries he's had in recent seasons?

It certainly doesn't seem to be, unless he's dealt with something outside of what has sent him to the IL in the past. He had a thumb ligament injury five years ago from a headfirst slide that resulted in surgery. He had a calf strain that cost him the bulk of last season. And he's had a few other odds and ends mixed in as well but, as far as we know, nothing rib or spine related.

Is this comparable to any other baseball player or athlete's injury?

Let's put it this way: Not as far as we know. Many athletes have dealt with rib injuries and many have dealt with spine injuries. Rarely do we hear an injury described with the level of specificity as Trout's. That doesn't mean another player hasn't had a costovertebral injury. In fact, it's highly likely that several players have dealt with something similar but we just may not be aware of it. It's also a credit to Trout's medical staff, including spine specialist Dr. Robert Watkins, with whom he consulted for this injury. Having people who will look for and are knowledgeable about the small details that inform the specific diagnosis can be key to a successful outcome.

*There are also five fused vertebrae below the lumbar spine that make up the sacrum, and the tailbone attaches to the bottom of the sacrum. Since they do not represent individual articulating joints, they are not included in the description above.