PTT dysfunction

Question 1

Describe what you see

Answer 1

• This is a clinical photograph showing a posterior view of feet in weight bearing position.
• There is
  Pes planus deformity and collapse of the medial longitudinal arch , hindfoot valgus, marked heel valgus and too many toes(more than 2 toes).
  Clinical findings are consistent with flatfoot or pes planus.
• In adults it is usually acquired and commonly due to tibialis posterior dysfunction.
• Other causes include inflammatory arthritis, Charcot arthropathy, osteoarthritis and trauma.
• It is commoner in females and the incidence increases with age.

Question 2

Tell me about posterior tibial muscle

Answer 2

• The muscle originates from the posterior fibula-tibia-interosseous membrane
• It is innervated by the posterior tibial nerve
• The tendon travels distally posterior to the medial malleolus before dividing in to three
  limbs
  1. The anterior limb inserts into the tuberosity of the navicular and the medial cuneiform
  2. The middle limb inserts into the 2nd-3rd cuneiform-cuboid-2nd through 5th MT
  3. The posterior limb inserts on the sustentaculm tali anteriorly.
• The PTT lies in an axis posterior to the ankle joint and medial to the subtalar joint.
• It acts as
  1. * Hindfoot inversion
  1. * Forefoot adduction and supination
  1. * It acts as a secondary plantar flexor at the ankle joint
• Activation of the PTT allows locking of the transverse tarsal joints creating a rigid lever arm for the toe-off phase of the gait.
• The major antagonist of the PTT is PB.
• There is watershed area between the navicular and the distal medial malleolus.
• Patients who suffer from PTTI develop a flatfoot deformity. The four classic findings of a patient suffering from PTTI are: collapsed medial arch, hindfoot valgus, forefoot abduction and varus?? (too many toes sign)

Question 3

How to test for the posterior tibilais power?

Answer 3

• The foot is positioned in planter flexion and full inversion
• If the patient is unable to maintain foot position when the examiner
  apply an eversion forces the patient is having weak PTT

Question 4

What is the classification system used for
this condition?

Answer 4

Jhonson classification with modification by myerson
* Stage I
There is no deformity, only tenosynovitis, the patient is able to do single heel raise test, and no arthritic changes on radiographs
* Stage II flexible hindfoot sub divides to
* IIA: flatfoot deformity, flexible hindfoot and normal forefoot, the patient is unable to
do single heel raise test, no arthritic changes on radiographs, there is collapse of the medial arch
* IIB:flatfoot deformity, flexible hindfoot and forefoot abduction with talonavicular angle (uncoverage of the talus) >40%, the patient is unable to do single heel raise test,
no arthritic changes on radiographs, there is collapse of the medial arch
* IIC:1st TMT instability.
* Stage III rigid hindfoot
Flatfoot deformity, rigid hindfoot and forefoot, unable to do single heel raise test and radiographs showed subtalar arthritis with no talar tilt
* Stage IV
Flatfoot deformity, rigid hindfoot and forefoot, unable to do single heel raise test and radiographs showed subtalar arthritis with talar tilt in mortise
view(hindfoot valgus)

Question 5

After your examination, how would you
investigate this patient?

Answer 5

Weight bearing foot A/P & lateral radiographs- ankle mortise
Ø A/P foot:
ü Talonavicular uncoverage
Ø Lateral view:
ü Decreased calcaneal pitch (normal angle is between 17-32°)
ü Increased (Meary’s angle) angles >4°and directed downword indicating pes planus.
Ø Ankle mortise
ü Talar tilt due to deltoid insufficiency seen in stage IV

Question 6

Talar tilt

Answer 6

• line drawn parallel to articular surface of
  distal tibia
• second line drawn parallel to talar surface
• The two lines should be parallel to each other
• Abnormal Occurs due to deltoid insufficiency

Question 7

Talonavicular uncoverage

Answer 7

• Two lines
• One connecting the edges of the articular
  surface of the talus and another connecting the
  edges of the articular surface of the navicula
• Normal angle is less than 7 degrees

Question 8

What are the treatment options?

Stage I

Answer 8

Stage I
Ø Non-operative
ü Initial period of immobilisation followed by shoe orthosis (UCBL with medial posting) + NSAIDs
ü Physiotherapy
Ø Operative :
ü Tenosynovectomy if conservative treatment fails

Question 9

What are the treatment options?

Stage II

Answer 9

Stage II
Ø Non-operative
ü Similar to stage I
Ø Operative :
ü IIA: medializing calcaneal osteotomy + FDL transfer to navicular bone from plantar to dorsal
(flexion of the lesser toes to be maintained by flexor hallucis longus via the knot of Henry.) +/- ETA
+/- spring ligament reconstruction. Then if the forefoot is supinated assess the 1st TMT , if stable
> plantar flexion opening wedge medial cuneiform osteotomy (Cotton).
ü IIB: add lateral column lengthening
ü IIC: if the 1st TMT is unstable or arthritic > fusion.

Question 10

What are the treatment options?

Stage III

Answer 10

Stage III
Ø Non-operative
ü AFO or arizona
Ø Operative :
ü Triple arthrodesis(subtalar, talonavicular, calcaneocuboid)

Question 11

What are the treatment options?

Stage IV

Answer 11

Stage IV
Ø Non-operative
ü Similar to III
Ø Operative :
ü If tibiotalar is not involved > hindfoot arthrodesis + deltoid reconstruction ??
ü If tibiotalar is arthritic > pantalar arthrodesis. Tibiotalarcalcaneal.