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Lis Franc's Dislocation
The Lis Franc,s joint is a combination of
joints in the middle of the foot. At the point where the long bones
behind the toes, called metatarsals, connect with a grouping of small
cube shaped bones, called cuniform bones, there are several joints the
move together in an interlocking fashion. This grouping of interlocking
joints is referred to as the Lis Franc's joint. The Lis Francﾒs joint
are bound together by a series of transverse ligaments on the top and
bottom of the joint, as well as an intermetatarsal ligament. This
grouping of joints is clinically called the tarsometatarsal joints.
Fracture-dislocations of the tarsometatarsal joint are named for Lis
Franc who was a field surgeon in the Napoleonic army.
Fracture-dislocations of the tarsometatarsal joint (Lis Franc's) is
extremely significant in that it is a commonly missed diagnoses with a
great potential for long term disability. Lis
Franc's fracture-dislocations can occur in many different ways. It can
be caused by both a direct crushing type injury or a force applied to
the metatarsal heads (ball of the foot) which both can result in
displacement of the Lis Franc's joint or fractures that in involve the
joint. Common causes are motor vehicle accidents, falls from heights,
severe foot and ankle sprains, crushing force to the top of the foot.
These injuries can occur during strenuous and competitive athletic
activities. The athlete who complains of sudden onset of pain, in the
middle of the foot during the course of an athletic event should be
carefully evaluated for a possible Lis Franc's injury. Diagnosis Diagnosis
is extremely important following the injury. Early diagnosis and
treatment can prevent long-term chronic pain and other sequalae.
Diagnosis is made by both clinical and X-ray modalities. On physical
examination there is marked tenderness across the tarsometatarsal joint
usually with pinpoint tenderness at the articulation of the second
metatarsal base and the medial and intermediate cuneiforms. Global
forefoot and midfoot swelling is commonly seen from several minutes to
several hours following injury. In severe dislocations it is very easy
to visualize a change in shape of the foot as compared to the other
foot. X-rays may reveal either a partial or total dislocation at the
tarsometatarsal joint. The difficult cases to diagnosis are those when
the joint dislocates and then relocates on itﾒs own. When this occurs
there may be little evidence of the injury on an x-ray. If there are no
X-ray changes and clinical diagnosis makes the doctor suspicious of
injury they may order stress X-ray, bone scan, CT scan
or MRI. In all acute injuries circulation must be monitored to assess
the possibility of compartment syndrome (increase in pressures within
the foot which can shut off circulation). This could result in loss of
oxygen to the tissues, which might result in loss of the foot. Treatment Closed
reduction should always be attempted in an acute fracture-dislocation.
Treatment involves general anesthesia to relax the patient and an
attempted reduction of the second metatarsal base into its anatomic
position is attempted. If the second metatarsal can be reduced then
metatarsals two through five may reduce without much manipulation. If
closed reduction is successful then reduction of the first metatarsal
cuneiform joint is performed and pins are inserted to allow for
stability during healing. If closed reduction fails it is usually due
to one of the foot tendons, which may be caught in the dislocated
joint. If closed reduction fails in an acute injury or the injury is
old then open reduction must be performed to reduce long-term problems.
If vascular compromise is evident this also constitutes a need for
immediate surgery. There are usually two to three incisions placed on
the top of the foot to allow for adequate visualization and
manipulation of the bones. Once the foot has been placed back into
anatomic position the tarsometatarsal joint is stabilized with either
pins or screws to allow for stability during the healing process. If
pins are used they are usually removed in six to eight weeks. Whether
pins or screws are used doesnﾒt really matter as the patient is
non-weight bearing for six weeks and is usually casted for at least
eight to twelve weeks. Following bony healing and return to ambulation
the patient will need a good functional foot orthotic
to provide support and relieve stress from the tarsometatarsal joints
and assist in pain free ambulation. Long-term prognosis for this injury
is guarded. When any injury involves a joint the likelihood of an
on-going arthritic process is likely. In sever cases fusion of the
joints may be necessary. In the athlete this injury can be devastating.
Rehabilitation to return to the same level of performance can takes
several months or longer.
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