Injury analysis: Making sense of Patrick Mahomes’ patellar dislocation
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Our in-house injury expert, Aaron Borgmann, weighs in on the injury Mahomes suffered on Thursday night.
By aborgmann Oct 18, 2019, 7:54am CDT
Photo by Justin Edmonds/Getty Images
Most fans know that Kansas City Chiefs quarterback Patrick Mahomes dislocated his patella (kneecap) last night in the game against the Denver Broncos. Let’s be clear on this: it was his kneecap that dislocated—not his knee, a big distinction.
This injury is seen frequently in contact sports with first-time traumatic dislocations accounting for approximately 3% of all knee injuries, according to a recent study.
While we couldn’t see the actual moment the injury happened at the bottom of the pile, what we did see was an excellent shot of a physician getting Mahomes to relax and extend his leg and his patella reducing or “relocating” back to its anatomical position. This is the preferred and correct method of acute management of the injury.
Diagram of the patellar when dislocated
As we can see in the picture provided, the patella moves out of its normal location laterally, to the outside, and rests there until reduced on its own or by a healthcare provider.
While this may seem fairly innocent, there are actually several ramifications that must be considered here.
First and foremost: was any obvious fracture noted of the patella itself or the lateral femoral condyle, and if so, to what extent is the damage? We have been told through reports that Mahomes did not suffer a fracture last night based on X-rays taken at the stadium, so that is the first thing to check off the list.
In some cases, if fractured, the possibility exists of loose bodies that are associated with the injury from the patella or the femur.
Second: we must consider the area that the patella sits in anatomically, called the trochlear groove. Was it damaged as the patella was forced out of its normal resting place?
Third and perhaps most importantly: was there any damage to something called the medial patellofemoral ligament (MPFL) and medial retinaculum? These are some of the main supporting structures holding the patella in place as it does its job.
One of the main reasons that we as clinicians worry so much about the medial structures in this injury is the fact that if they are compromised, the chance for re-dislocation increases dramatically.
This injury typically comes with swelling in most who suffer it acutely and for the first time — others who chronically dislocate, less so. There is a correlation here, which notes that a larger volume of swelling is more indicative to the amount of damage suffered to the medial structures.
The reason an MRI is so important here is to look at the surfaces of the patellofemoral joint and to determine the location/level of any soft tissue damage to the all the medial stabilizing structures that we mentioned above.
The other scary part here is that some fractures in these injuries are missed by plain X-rays alone, then identified with MRI or surgery, up to 30-40%. A CT scan can be helpful here if a diagnosis of fracture is questionable.
After diagnosis and assessment of damage comes the biggest question.
Does the level of damage warrant more immediate intervention or is non-op treatment acceptable in the short-term?
Again, everything comes down to how the medial supporting structures look and is there any articular cartilage damage that would be made worse by playing on it. These patients are always assumed to have that cartilage damage until ruled out due to the violent nature of the injury.
If non-operative and no associated damage, I have seen athletes play quickly here, although for first-time dislocations, we typically err on the side of caution just to make sure. Chronic dislocators will note “popping it back in” and returning to next play or series. That’s not the case here.
Rehab here consists of much swelling control and early protected motion. Getting the larger quad musculature back in a timely fashion is key to a quick recovery. I have seen many cases where rehab was attempted here initially and given the questionable stability at the knee, it didn’t work.
Positional and sport demands have to be taken into consideration as well as—this is Mahomes’ right leg and will be in a plant/post position during his throwing motion and dropback.
The bottom line
If there is a need to have reconstructive surgery to address either articular cartilage defects or the medial supportive structures, that would likely end Mahomes’ season due to the recovery timeline.
Even if Mahomes can play with this injury now and recover quickly in a matter of weeks, the possibility exists for surgical intervention after the season is over to address the issue long-term, as the factors for a chronic dislocator aren’t great for a professional football player.
In short, the chances are greater than not that Mahomes will need to have this issue surgically addressed at some point in the future to ensure more long-term success.
