Bones are great in compression, but they suck in rotation.
And the recent Josh Naylor injury is going to help me to explain why.
Hey Interns, I’m Dr. Chris Raynor and I am not your everyday ortho.
Today I am going to look at the recent injury suffered by Cleveland’s Josh Naylor,
and I going to use this injury to explain why bones are
fantastic in resisting compression forces, but absolutely suck when it comes to rotation.
how many times do i have to say it!?
Not even notorious superstars can avoid this fact—
Remember what happened to Conor McGregor in ufc 264? But enough on that—
Today our patient is Josh Naylor
While attempting to catch a fly ball in the outfield,
Naylor collided with his teammate, Ernie Clement, and was thrown into the air.
An awkward landing resulted in a deformity of his right lower leg. Ouch! Looks like he’s in
a lot of pain. His lower extremity looked to be unstable as he moved around on the turf.
Eventually, he was stabilized by the medical staff, and transported to a
hospital in Minnesota for further examination. He later returned to
Cleveland to see foot and ankle specialist Dr Mark Berkowitz; the official diagnosis?
a closed ankle fracture dislocation with associated ligament injury. For which
he underwent reparative surgery on July 2, 2021.
That’s the information that we were given.
But what other information can we figure with our own critical eye?
After some review, I have come to the following conclusions:
1. the Timing of injury,
2. the Injury mechanism and corresponding Fracture type,
3. the fracture location, 4. the type of fixation expected.
When Naylor collides with Clement, Naylor is in the process of lifting his right leg
off the ground. Clement, on the other hand, is in the process of planting his right leg.
As their right legs collide, Clement’s momentum launches Naylor’s right leg in the air,
adding an element of rotation. Combined with Naylor’s forward momentum,
the elevation and rotation caused Naylor to spin around in the air.
When he contacted the ground, the toes of his right foot struck first with his centre
of gravity behind the point of contact. The cleats on his shoes caused his right leg to stop moving,
while he continued to fall to the ground. Naylor was still rotating at this point while his leg was
fixed, forcing his right lower leg into external rotation as he continued to fall backwards.
Eventually, the fibula could not resist the torque applied by the forced external rotation
and it fractured at the level of the ankle. So while the initial impact with Clement looks
more spectacular, it is in fact his impact with the ground that caused the injury.
I repeat: forced external rotation of the foot, on the leg, or rather the falling body
around the fixed foot, which caused the fracture to occur.
The fracture pattern that is typically associated with this injury mechanism
is a spiral oblique fracture of the fibula. This is a fracture that travels in a diagonal path
down the fibula from one side of the bone to the other in a curved line. It can occur right
at the level of the ankle, or a short distance above. In severe cases, it will occur with one
or two fractures of the distal end of the tibia on the inside and at the back.
In Naylor’s case, the fracture occurred as well as a dislocation of the ankle joint. This combination
of injuries is called either a biomalleolar or trimalleolar dislocation of the ankle,
depending on whether there are one or two fractures of the distal tibia
as well as a fracture of the fibula. It is not clear which one Naylor suffered.
Fortunately, it was a closed injury without any bone protruding out through the skin
which would have increased the severity level.
Generally speaking, there are three levels at which a fibula fracture can occur : below,
at, or above the joint line. It is uncommon to have the amount of instability demonstrated
in Naylor’s video with a fracture that occurs below the joint line.
This means that his fracture was either at or above the joint line.
With a bimalleolar or trimalleolar ankle fracture,
both the fibula and the tibia need to be fixed. With a bimalleolar fracture
there are two fractures that need to be fixed. A trimalleolar has three.
The standard fixation includes plate and screw fixation on the fibula which is usually fixed
first which allows us to restore the normal length and rotation of the limb.
This is done through a lateral incision directly over the fibula. Through a separate incision on
the medial or inside part of the ankle, the medial tibia fracture is fixed. Fixation usually only
requires screws, however if the medial fragment is particularly large or particularly unstable,
a plate may be used on this side as well.
In the case of a trimalleolar fracture if present, the need for fixation depends on
the size of the fragment and the amount that it is displaced or moved out of normal position.
If the trimalleolar or fragments at the back of the ankle are less than 25% of the joint
surface and are not displaced more than a few millimeters this part does not require operative
fixation. These cases are reduced into position manually and stabilized by post operative casting.
However if the fragments at the back of the ankle are bigger than 25%
of the joint surface and displaced more than a few millimeters, then fixation is required.
We use either screws alone or plate and screws together depending on the size.
Post operative rehab will include 6-8 weeks cast immobilization and non-weight bearing
if all goes according to plan. If healing is going well, some weight bearing in the cast
might be allowed around 4 weeks. Full weight bearing will begin once fracture
healing has been confirmed. Physiotherapy will start as soon as the cast is removed.
Normally, it will be approximately 4 to 5 months before we can expect
Naylor to return to training and/or practice,
but it will likely be around 6 months before we can expect him to return to normal play.
So now that we know how and when the fracture occurred, we want to figure
out why the fracture occurred in this manner. Why is it that bones are weak in rotation?
It all comes down to how bones are designed. Each Bone is made of up of
two types of bone, compact cortical bone and spongy cancellous bone.
Cortical bone is on the outside, while cancellous bone is on the inside. Cortical bone is arranged
somewhat like a bundle of pipes (Osteons) that have been tightly tied together by small channels
called canaliculi. These pipes called osteons are insulated by a layered covering, called a matrix.
Bone cells called osteocytes live in between the matrix layers.
Cancellous bone on the other hand, is less dense than the cortical bone. Think of it like
plates of bone (trabecule) and bars of bone randomly arranged with small irregular cavities
that contain bone marrow. Neighboring cavities are connected by channels. The plates of bone are
arranged to provide maximum strength in line with the stress traveling through the bone.
When bones fail under compression (axial loading),
cracks form in between the pipes and travel down the bone vertically. These vertical cracks
continue to form between the pipes without the bone failing for a long time. Eventually,
the pipes spread apart enough and the bone collapses…..suddenly. This is failure in
a single vertical fashion//mode/plane, the effects having accumulated over time.
When bones fail under tension (bending) ala Conor McGregor,
cracks form in the alternate horizontal plane along the channels joining the pipes.
This type of failure occurs much more progressively than with compression.
Pipes bend gradually over time with damage occurring more slowly before eventual collapse.
Rotation, however, is different than either compression or tension. With rotation,
when bones fail, cracks form in between the pipes and following
the channels joining the pipes. This means failure occurs in both the vertical
and horizontal planes , and occurs suddenly with a significant amount of damage occurring
immediately before failure. Because failure involves multiple planes,
it is more aggressive and results in the most damage of all failure types. So that’s why bones
are great in compression, but suck in rotation, and are only marginally better when bent.
Thanks for watching. I’ll see you all next week. As always,
that’s been a word from Dr Chris, not your everyday Ortho.