It’s Just a Bruise, Right???

The American League Central-winning Kansas City Royals are steamrolling into the playoffs that get started this week.  Kansas City has been abuzz this week over All-Star centerfielder Lorenzo Cain and the “bone bruise” he’s battling in his knee.  Lorenzo’s tough and it sounds like he’s going to grind it out and make it through the playoffs (hopefully!).  Right now, the Royals are saying it’s a four-week injury.  Seems crazy since it’s “just a bruise” right?  Or is it?

What’s a bone bruise?

Think of the ends of bones, like our “thigh bone” or femur, as a snow-capped mountain.  The “snow” is our cartilage, the rocky mountain as the bone itself.   Hopefully that analogy makes sense – a softer material covers a much harder material.  Cartilage acts as a shock absorber for our joint.  Healthy cartilage is similar to a wet sponge – it’s imbibed with water and it can be “squeezed” to tolerate loading or compression.  When an athlete gets a bone bruise, there is damage to the cartilage, like tiny little cracks in an eggshell.  The more severe the bone bruise is, the further it extends down the cartilage and sometimes into the bone itself.

How do bone bruises happen?

Bone bruises basically happen when two bones impact each other.  Think two rams butting heads with each other.  They happen when athletes land or cut awkwardly or when they sustain an injury on one side of the joint that causes an injury on the opposite side of the joint.  For example, when the knee “buckles” inward, the inside of the knee “opens” while the outside or lateral side of the knee is compressed.  The compressed side, the two rams, is what causes the bone bruise.   In baseball, they can also happen too from getting hit by a pitch – but that’s more on the “outside” of the bone, not the weight-bearing surface which is more painful.

Why do they hurt so much?

Basically, a bone bruise just makes it painful to play.  It can hurt to run, jump, cut, and land.  Bruises are tender on our bodies, imagine two bones hitting each other!

Will it really take four weeks?

It sure can.  Usually, the medical staff estimates how long an athlete will be out based on how far the bruise extends into the subchondral (below the cartilage) bone.  That can only be determined on MRI, and again, it’s only an estimate.  Some studies have shown they take 12 weeks to heal.  Whereas, some bone bruises, like after an anterior cruciate ligament (ACL) tear, can take up to a year to heal.

Can you speed up healing with rehab?

Bone bruises ideally need rest and reduced impact.  Not good for Lorenzo Cain on the verge of a playoff run.  Cyclical, non-weight bearing motion like riding a stationary bike or deep water running is the “best medicine” for bone bruises.  The medical staff will likely limit extra running and minimize his impact loading.  Things like pulsed ultrasound and laser therapy may also help a little, but truly, these injuries need time.
Good luck Royals and stay healthy Lorenzo!  Kansas City is pulling for you!