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Coalition of
the Middle Facet
An excellent, comprehensive discussion of Tarsal Coalitions
is part of PRESENT Courseware. View
Dr. Michael Trepal’s lecture on Tarsal Coalition and hear his thoughts
on the subject. An enhanced summary of the lecture appeared in our weekly
Featured Lecture
Series on October 2, 2003. We hope each residency program will submit a
case to Residency Insight Grand Rounds this year.
Tarsal Coalitions are fairly rare abnormalities. Symptoms often do not appear
until later in life. There are many theories regarding the cause. The first is a
failure of differentiation and segmentation of primitive mesenchyme. The second
is incorporation of accessory ossicles into the normal tarsal bones on either
side of the joint. The Os Sustentaculum Proprium may play a role in middle facet
fusions.
Intra articular coalitions are most commonly treated with arthrodesis
procedures. In some instances, however, an attempt can be made to resect the
coalition, given that secondary degenerative changes are not advanced. Younger
patients with incomplete, non-osseous coalitions will be better candidates for
these procedures.
Case Presentation
An 18-year-old male presented with chief complaint of pain in
the posterior medial aspect of the left heel. The discomfort was particularly
noticeable after athletic activity and extended periods of ambulation. The
patient had been treated for insertional tendonitis in the past.
PMH – unremarkable
Meds - None
Allergies - penicillin
Social – does not smoke, does not drink alcohol
Neurovascular - wnl
Orthopedic – Examination revealed severe restriction of motion on
inversion and eversion of the left foot. No joint crepitation was evident within
the confines of the restricted motion. The arch of the medial column was
preserved bilaterally. Full and unrestricted motion was evident on the right.
Gait Analysis – Moderate antalgia was evident on the left. No excessive
pronation was evident on either foot.
Radiographic Evaluation – Revealed obscurity of the middle and posterior
facet of the left subtalar joint. Talar beaking and osteochondral fragmentation
of talonavicular joint was seen as well. On the right, the middle and posterior
facet are clearly visualized as well as the sinus tarsi
MRI - Ankle tendons intact, no ligamentous
abnormalities, preservation of posterior subtalar joint. Suspicion of fibrous or
cartilaginous coalition at the middle subtalar joint.
CT Scan - Talocalcaneal tarsal coalition involving the sustentaculum tali
and middle fact of the talus. The talonavicular and calcaneo cuboid joint spaces
are preserved.
Plan
The pathology was discussed with the family in detail. A
decision was made to remove the coalition with the understanding that the
benefits may be limited and the patient my ultimately go on to triple
arthrodesis. In essence we were attempting to “seize the opportunity” that may
not be available to the patient later in life.
Surgical Procedures
A medial approach was
utilized, extending inferior and posterior to the medial malleolus and extending
anteriorly. The posterior tibial and flexor digitorum tendons were retracted
plantarly. Care was taken to preserve the neurovascular structures. The
sustentaculum tali was identified using intra operative fluoroscopy. A remnant
of the middle facet was identified using the tip of a Freer Elevator.
An
aggressive removal of the coalition was performed, leaving the sustentaculum
tali intact. The joint surfaces of the posterior fact were visualized intra
operatively and found to be well preserved. Bone wax was applied to either side
of the joint surfaces.
Improved
range of motion was appreciated both manually and fluoroscopically. The patient
was immobilized for one month and then started on range of motion exercises.
Here is the post-op radiograph.
Notice the absence of the middle facet.
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Jay Lieberman, DPM
Editor - PRESENT
Director of
Podiatric Medical Education
Northwest Medical Center
Margate,
Florida
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