Subluxation is the medical term used to describe the action of one or more
anatomical parts slipping or moving out of its' normal position. Peroneal
tendon subluxation refers to a recurrent snap or popping sensation of the
peroneal tendons on the lateral (outside) aspect of the
ankle.
Peroneal tendon subluxation occurs during gait while the tendon is loaded.
Subluxation of the peroneal tendons occurs as the tendons jump from the peroneal
groove behind the fibula (outside ankle bone)
to the side of the fibula and back into the groove.
The peroneal
retinaculum is a small fibrous band that acts to restrain the peroneal tendons in a deep groove on the back
of the fibula. Peroneal tendon subluxation occurs when the peroneal retinaculum
is damaged or injured.
The peroneal retinaculum is often injured in a
lateral ankle sprain. Other causes of subluxation include anatomical variations of the fibular groove that may make the groove shallow and less able to
inhibit the peroneal tendons from subluxation during ankle motion.
Another interesting injury in the region of the fibular groove is a compression injury to the peroneus brevis tendon
resulting in a
longitudinal peroneal tendon tear. Several authors have described a mechanism by which the peroneus longus tendon actually cuts into the brevis tendon, effectively splitting the brevis tendon. There appears to be a statistical relationship between
peroneal tendon ruptures and recurrent peroneal tendon subluxation.
Treatment of recurrent subluxating peroneal tendons
A period of conservative care should be observed following an acute injury to
the peroneal tendons. A
walking cast,
ice and
a compression wrap
may help to enable healing of the peroneal retinaculum. A lateral sole wedge
can be used to limit load to the peroneal tendons by inhibiting supination of
the foot (rolling out).
Lateral
sole wedges can be placed
in the shoe, on
specialized
orthotics or applied to the outer sole of the shoe by a shoe repair shop or
O&P facility. In cases of chronic
peroneal tendon subluxation, surgical repair will be
required to prevent subluxation and long term damage to the peroneal tendons. Treatment of peroneal tendon subluxation involves deepening the peroneal groove of the fibula
and retinacular repair. A number of different methods have been described in the surgical literature to add depth to the
peroneal groove, thereby limiting peroneal tendon subluxation. Those methods include drilling, tamping and creating rotating osseous (bone) shelves. Repair of the peroneal retinaculum may be accomplished by direct suture repair or by a supplemental graft from the Achilles tendon.
When surgically treating peroneal tendon subluxation, it's important to
remember to treat any biomechanical factors that may contribute to lateral
instability and ankle sprains. It's important to recognize that these
biomechanical factors may be the contributing causes of what caused the peroneal
tendon subluxation in the first place. If these biomechanical
co-morbidities are not addressed, surgical repair of peroneal subluxation may be
doomed to failure. Two common biomechanical faults found in conjunction
with peroneal tendon subluxation include lateral ankle ligament instability and
uncompensated rearfoot varus.
Lateral ankle ligament instability and ligament tears contribute to
ankle instability and recurrent
ankle sprains. If ligament laxity is not addresses and lateral ankle
sprains continue, surgery to correct peroneal tendon subluxation is likely to
fail. It is not unusual to perform a Brostrom lateral ankle stabilization in
conjunction with a repair of peroneal tendon subluxation.
Uncompensated
rearfoot varus is a structural deformity of the heel. Rearfoot varus is an
often overlooked contributing factor in recurrent
lateral ankle sprains.
Uncompensated rearfoot varus is another biomechanical issue that is often
corrected in conjunction with correction of peroneal tendon subluxation.
Correction of uncompensated rearfoot varus is accomplished by a
Dwyer osteotomy of the heel.
