Hey everyone, it’s Raj from 3CB Performance.
Demarcus Cousins picked up another serious injury - a complete anterior cruciate ligament,
ACL, rupture - in his left knee playing in a pick-up game while trying to get back to
100% fitness after an achilles rupture in late January 2018 while playing for the Pelicans
and a partial left quad tear in the first round of last seasons’ playoffs while playing
for the Warriors.
Obviously another major injury - his third within eighteen months - on the same leg is
clearly a major cause for concern, especially as he’ll now have another 7+ months of rehab,
lost fitness, and even more residual deficits.
However, my focus in this video is to take the injury analysis multiple levels deeper
by explaining how the series of injuries are all connected and why the way he tore his
left ACL - aka the mechanism of injury - is the reddest of red flags and may indicate
that Cousins is fundamentally physically compromised.
When a player gets hurt, of course the diagnosis is very important because it informs you of
severity, timetable and risks. However, what I also look at is how the injury happened,
known as the mechanism of injury.
I’ll ask questions like: Was it contact or non-contact? Does the injury make sense
based off the specific movement during which it happened? What other factors could be in play?
These questions and answers provide a wealth of information on potential root causes and
underlying deficits that may have caused the injury.
In Demarcus’ case, his first two injuries made sense but his ACL rupture hints at something
far more nefarious and compromising. Lets take a look at each.
Demarcus’ left achilles rupture occurred while he was doing a quick double jump on
a rebound. This movement puts a huge stress on the achilles tendon as it first has to
elongate while contracting - known as eccentric contraction
and then like a spring to push off the ground.
That’s a common mechanism of injury for the achilles tendon.
Further, in the lead up to the rupture, Demarcus’ game minutes had jumped up significantly which
is another risk factor because increasing week to week activity by over 10% has been
found to increase muscle and tendon injury risk by as much as 7x. This is known as the
acute to chronic workload ratio.
Additionally, that jump in minutes can lead to increased fatigue which is another known
risk factor for soft tissue injury.
Demarcus’ left partial quad tear - like his achilles tendon rupture - also made sense
based on the MOI. He was chasing after a loose ball and decelerating to gather it. This movement
created a triple stress on the quads - specifically the rectus femoris muscle - as it’s actively
involved in flexing the hip
AND eccentrically controlling knee flexion (bending) to slow
down the front leg and create a stable base of support, all on the dead run.
That’s a massive stress on the rectus femoris which was potentially already weakened from
residual muscle atrophy that’s been shown to occur for up to two years on the injured
leg after an achilles rupture.
Additionally, the quads were likely taking on more stress than usual for three reasons:
Firstly, a weakened achilles and calf complex - again from the achilles rupture - means
a larger force shockwave into and above the knee.
Secondly, the playoffs are a higher intensity setting which leads to increased physical
exertion and load through the body. To that point, the research shows a positive relationship
between match intensity and injury risk.
Thirdly, all the muscles in his left leg - including the quads which are major stabilizers and
movers - were compensating for the recovering achilles tendon and taking on more stress.
Demarcus’ ACL rupture doesn’t make much sense based on the MOI as he injured the knee
while loading up his left leg to finish a right handed layup. This movement typically
stresses the quads to control knee flexion (bending)
and stresses the hamstrings and calf complex to control the tibia (shin bone)
as it translates forwards.
And yet, Demarcus - who had also lost considerable weight to decrease the amount of load and
force he was putting through his body - ended up fully rupturing the ACL. This sequence
places very mild stress on the anterior cruciate ligament but nothing that comes close to even
moderately tensioning it, let alone completely rupturing it.
It’s a complete mismatch of movement and injury which immediately led me to believe
that Cousins’ left leg has been fundamentally compromised.
A key component of biomechanical function and physical viability is a concept known
as “active vs passive stabilization”.
Active stabilization refers to the body’s muscles and tendons actively contracting during
movement to stabilize joints and attenuate stress. They’re the body’s main shock absorbers.
On the other hand, passive stabilization refers to anatomy like the ligaments and joint capsules
which don’t actively contract but provide added static stability to help keep joints
within their normal range of motion.
These passive constraints are secondary stabilizers and generally don’t attenuate nearly as
much stress as the active stabilizers. To that point, we’re seeing more and more research
showing that after an ACL rupture, extensive rehab and muscle strengthening can be just
as effective as surgical intervention and rehab. Highly functioning muscles and tendons
can actually make up for the loss of stability from the ACL.
When Demarcus loaded his left leg to jump, his left quad, hamstrings, and calf/Achilles
complex - the primary active stabilizers during that movement which should’ve been taking
the majority of that load - didn’t, leaving the ACL to fend for itself and take on a level
of stress it wasn’t built for, resulting in the full rupture.
This lack of active stabilization is an extremely red flag and fundamentally compromises the
mechanics and function of the body. There are two primary underlying reasons I can think
of for why Demarcus’ active stabilizers were compromised:
The most obvious reason is muscular strength and endurance deficits. As I said earlier,
the research shows it can take over two years to achieve equal side to strength after an
Achilles rupture with calf atrophy lasting even longer.
Further, you add his partial quad tear which further exacerbates the side to side strength deficits.
The cherry on top is that Demarcus was in rehab for the better part of 18 months which
naturally results in a loss of overall fitness as well. This only compounds the strength
deficits as well.
The neuromuscular system is the connection between the nerves and the soft tissue -
muscles, tendons, ligaments, and so on.
The wiring - the nerves - signal the machinery - the soft tissue - to turn on when they’re needed.
If that connection is damaged or hindered,
it leads to altered muscle and tendon activation and altered proprioception, which is your
body’s unconscious awareness of joint positioning, transmitted to the brain by tiny cells called
proprioceptors housed in muscles and ligaments. In other words, the active stabilizers are
impaired because the nerves aren’t telling them what to do or when to do it, as quickly
as the nerves should be.
Research shows that injuries - particularly those with excessive swelling - can hamper
and inhibit the neuromuscular system, called neuromuscular inhibition. Further, recent
research is actually showing that the brain itself is affected after certain injuries
with changes to the brain’s postural and movement control centers. This isn’t only
after severe injuries, even minor ankle sprains are potentially resulting in those brain changes.
Everything in the mind and body is connected and now the research is beginning to reinforce
the practical changes.
Even if we do assume that Demarcus’ muscle and tendon strength and endurance was the
level it needed to be, it wouldn’t matter if the wiring wasn’t working. That’s the
danger of neuromuscular inhibition, it fundamentally compromises the entire system.
All in all, I had a positive outlook for Cousins when the team originally signed him - he was
extremely motivated, lost significant weight to decrease the load on his body, the partial
quad tear had healed, and the research shows it typically takes about two years for players
to return to pre-injury levels after an Achilles rupture.
I was looking forward to seeing him really ramp up closer to his old form as he hit that
two year mark near the 2020 All-Star break and into the playoffs. But that all changed
when I saw how the injury happened and the mismatch between mechanism and severity.
The red flags began waving.
Accordingly, I’m fairly confident that if he didn’t get injured now, it would’ve
happened at some point during the season. These fundamental deficits now indicate to
me that it’s an extreme long-shot for him to ever get close to his previous form or
perhaps even make it through a season healthy as he faces yet another lengthy 7-9 month
rehab process, even more residual deficits that will further build on and compound his
current ones, and another overall loss in fitness.
The key thing for him right now is simply to get his mind right.
Thanks for watching. My goal is to provide you with in-depth, evidence based, narrative
free analysis and you can always find me on IG and Twitter @3CBPerformance along with
my own YouTube channel where I deep dive into player injuries of all shapes and sizes.
3CB out.