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Jon K. Sekiya, MD
John E. Kubn, MD ABSTRACT Instability to the proximal
tibiofibular, or TF joint, are rarely recorded but may occur more often
than previously thought. The
injury most commonly occurs with violent twisting of the flexed knee, as
often seen in wrestling, gymnastics, skiing, basketball, and other more
aggressive sports. The
condition may be confused with bicipital tendonitis, hypermobile or torn
meniscus, postero-lateral rotational instability, or ITB syndrome. The joint is a synovial joint, and
in 12% of the population, it actually communicates with the knee joint.
The joint capsule is thicker anteriorly than posteriorly, and the
anterior portion has 3 broad ligamentous bands that pass obliquely as they
travel to their insertion in the lateral tibial condyle.
The posterior portion has two ligaments, which travel from the
fibular head to the lateral tibial condyle.
The posterior ligaments are also reinforced by the popliteus
tendon, and the postero-lateral knee structures also stabilize the joint.
The LCL supports the proximal TF joint, and as it becomes lax after
30 degrees of knee flexion, the joint is more susceptible to injury. There are two anatomic variations
of the joint in humans. The
horizontal variant has less than 20 degrees of joint inclination, and the
fibular head is seated behind a fairly prominent lateral tibial ridge,
which enhances stability. A
second variant, the oblique variant, is defined by any angle of
inclination greater than 20 degrees.
This joint has a decreased surface area within the joint, which
predisposes it to instability. There are 4 types of instability of
the proximal TF joint: atraumatic
subluxation, anterolateral dislocation, posteromedial dislocation, and the
rare superior dislocation. Anterolateral
is the most common and involves injury to both the anterior and posterior
ligaments. This usually
results from a fall on a hyperflexed knee and also usually injures the
LCL. The fall on the
hyperflexed knee may also involve a plantarflexed and inverted foot, and
with the laxity to the LCL and hamstring tendons in this position, the
fibular head can dislocate and migrate anteriorly.
Posteromedial dislocations are not as common, but usually involve
injury to the peroneal nerve. This
can occur from a direct blow, such as when the knee hits a dashboard
during a wreck. This type of
injury can also occur when there is a strong contraction of the biceps
femoris while the knee is twisting, pulling the fibular head backwards.
The superior dislocation is rare, and usually occurs from trauma
that directs forces upwards, as in a fall.
This injury also occurs with concomitant interosseous membrane
damage. Clinical presentation may include
pain, swelling, reluctance to weight bear, limited knee extension,
crepitus, and visual deformity. The
patient may have a history of generalized ligamentous laxity, especially
younger patients. The popping
and cracking that occur can mislead the clinician into thinking there is a
meniscal problem, a postero-lateral knee problem, or an ITB snapping
situation. The physical exam
should take place with the knee flexed to 90 degrees to relax the LCL.
Grasping the fibular head in the fingers and applying an anterior
and posterior force may reproduce the patient’s complaints of pain or
instability feelings. The
Radulescu sign is performed by having the patient lie prone with the knee
flexed to 90 degrees. One
hand stabilizes the thigh, while the other internally rotates the lower
leg to see if the fibular head can be dislocated anteriorly.
Radiographs and axial CT can be used to confirm the diagnosis Treatment of atraumatic instability
can include cylinder casting for 2-3 weeks, a supportive strap, and
gastroc strengthening. Acute
dislocation treatment is still argued, with some favoring immobilization
for 3 weeks with the knee slightly flexed, while others reduce the
dislocation and simply limit weightbearing.
One study found that even with the immobilization, there was a 57%
continued problem rate requiring future surgery. Surgical treatment can include
resection of the fibular head and neck while maintaining the styloid, or
fusion of the joint. Neurolysis
is performed when there is scar tissue at the location of the peroneal
nerve. Resection has been
shown to lead to future foot/ankle and knee problems, and should not be an
option for athletes. COMMENTS This is a region of the lower
extremity that is often clinically neglected.
I usually perform a brief evaluation when treating knee and ankle
sprain patients just because of my own personal history. I suffered a significant ankle sprain during high school
wrestling (actually I found out years later I had broken it, which
explained the continued discomfort! I
still finished the season!). When
the sprain occurred, I immediately thought I broke my lower leg, as that
is where the pain occurred, and we all heard a loud snap that emanated
from my knee. It wasn’t
until I began practicing with a good group of ortho PT’s that fibular
head subluxation was discussed, and I realized what had occurred.
It must have self-reduced and there are no residual symptoms, but I
have had other athletes that acknowledge pain in that area after a severe
inversion sprain. I also had
a patient recently who suffered a tri-malleolar fracture, required an
ORIF, and now has peroneal palsy. This
type of dislocation most likely occurred, and the patient was educated
appropriately so that the surgeon did not get blamed for the problem
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