This article is part of our Injury Analysis series.
The Kansas City quarterback is expected to miss an extended period of time after suffering a knee injury in a win over the Broncos. Holmes suffered a dislocated patella (kneecap) while attempting a quarterback sneak. The Chiefs medical staff acted quickly and were able to return the patella to its normal alignment on the field.
Let's start by noting that this isn't a knee dislocation. In a true knee dislocation, the bones of the lower leg are forced out of their normal alignment with the femur. This applied stress is often accompanied by serious ligament damage and can resulted in blood vessel damage, making it a potentially limb-threatening injury. Several players including Zach Miller and Teddy Bridgewater have suffered this severe injury in recent seasons.
A patella dislocation is significant but not as traumatic as a knee dislocation. The patella is a mobile bone that runs in a groove known as the trochlear groove. As the knee moves, so too does the patella, moving up and down in this groove. However, if enough stress is applied to the patella it can become dislodged from the groove, similar to a train jumping its tracks. Often the malalignment will be temporary, and the patella will quickly return to its initial positioning. This is known as a subluxation. However, a dislocation occurs if the patella is forced out of alignment and stays out place until it is forced back into its normal position. Again, video from the field shows a Chiefs