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Peroneal Tendon Dislocation
Dislocating peroneal tendons are an uncommon
injury to a group of two tendons whose muscles originate on the outside
of the calves. These two muscles are named the Peroneus Brevis and Peroneus Longus. These two muscles are responsible for eversion
of the foot. This movement of the foot is demonstrated by standing and
then rolling to the outside of the foot. These tendons are also called
"stirrup" tendons because as they pass into the foot they act as a
stirrup to help hold up the arch of the foot. As these tendons pass
behind the outside ankle bone, called the fibula, they are held in
place by a band of tissue called the peroneal retinaculum.
Injury to the retinaculum can cause it to stretch or even tear. When
this occurs the peroneal tendons can dislocate from their groove on the
back of the fibula. The tendons can be seen to roll over the outside of
the fibula. This will cause the tendons to function abnormally and can
cause damage to the tendons. Dislocating peroneal tendons most commonly
occur as a result of injury during participation in athletic
activities. The most common sport causing injury is snow skiing. It can
also occur while playing football, basketball, and soccer. This injury
can occur in non-athletes, as a result of a severe ankle sprain. The
injury typically results in a popping or sharp pain on the outside of
the ankle. The outside of the ankle is called the lateral malleolus. Commonly however, there may be little to no discomfort at the time of injury, which later becomes symptomatic. Diagnosis Physical
examination will reveal swelling behind the outside of the ankle if it
is an acute injury. If the injury is chronic there may be little to no
swelling. There is usually tenderness particularly when pressure is
applied behind the outside of the ankle. Having the patient forcefully
turn the foot outward against the physician's hand can demonstrate
dislocation of the peroneal tendons. This will cause the peroneal
tendons to dislocate over the outer edge of the lateral malleolus. X-rays
and occasionally an MRI exam may be necessary to confirm the diagnosis.
X-rays are commonly taken to ensure that there are not any other
injuries to the bones of the foot and ankle. An MRI will provide your
physician with information about abnormal positioning and/or possible
tears of the peroneal tendons. Treatment Non Surgical Treatment If
there is an acute injury the initial treatment is usually crutches with
no weight being applied to the foot. Usually a splint or compressive
wrap is applied to decrease swelling. Anti-inflammatory medications and
ice are often utilized to help decrease swelling. Once the swelling has
subsided your physician will be better able to tell the true extent of
injury. Mild injury can be treated with conservative, non-surgical
means. Mild injury results in stretching of the peroneal retinaculum
without dislocation of the peroneal tendons. The patient is placed in a
cast or removable cast boot and must use crutches for six weeks. During
this time no weight can be applied to the foot. After six weeks the
patient is re-examined. If the injury has not healed further treatment
may be necessary. Surgical Treatment Surgical correction
is necessary in cases of failed conservative therapy and moderate to
severe injuries. With moderate to severe injuries the peroneal
retinaculum is either torn or severely stretched to a point that the
peroneal tendons will easily dislocate. Surgery will involve tightening
the stretched or torn peroneal retinaculum. Both absorbable and
non-absorbable suture or stitches will be necessary to hold the tissue
in place until it heals. This may require drill holes or metallic
anchors to be placed in the fibula to aid in suturing the peroneal
retinaculum back onto itself. Twenty-five
percent of the population does not have a groove on the back of the
fibula for the peroneal tendons to move in. This groove is called the peroneal groove.
This can be a causative factor for peroneal tendon dislocation and can
only be identified at the time of surgery. If this is encountered
during surgery a peroneal groove will be created by performing bone
cuts in the back of the fibula. These may require bone screws or pins
to hold the bone in place while it heals. During the surgery the
peroneal tendons will be examined for possible tears or damage. If this
is found it will be repaired by suture. Post-operatively
the patient is placed on crutches and in a splint or cast for 4 to 6
weeks with no weight being applied to the foot. This is followed by 2
to 4 weeks of protected weight bearing in a cast or removable cast
boot. This is usually followed by 3 to 6 weeks of physical therapy to
regain strength and motion. Potential Complications Once
an injury occurs it is always possible for a person to re-injure or
re-dislocate their peroneal tendons. Surgical complications are rare
but can include: infection, reoccurrence, stiffness and weakness of the
peroneal tendons, and delay or failure of bone cuts in the fibula to
heal. The risk for complications is greatly reduced by taking your
prescriptions as instructed and strictly following post-operative
instructions.
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