Midfoot Arthritis Pathway Updated: 10/4/2016
CPT Codes: 28725 Arthrodesis; subtalar

Subtalar Arthrodesis

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Preoperative Patient Care
Operative Techniques
E

Preoperative Plan

1

Radiographic templating

  • CT scan
  • determine length and placement of the implant

2

Execute surgical walkthrough

  • describe the steps of the procedure verbally to the attending prior to the start of the case
  • describe potential complications and steps to avoid them
F

Room Preparation

1

Surgical instrumentation

  • guidepins
  • 6.5 mm and 4.0 mm large fragment cannulated lag screws

2

Room setup and equipment

  • standard OR table
  • bring fluoroscopy from the contralateral side

3

Patient positioning

  • supine position
  • align sole of the foot with the end of the bed
  • place a soft bump under the ipsilateral sacrum to internally rotate the foot
  • place tourniquet around the upper thigh
G

Approach

1

Mark and make incision

  • start incision 1 cm below the tip of the lateral malleolus.
  • continue incision distally until the base of the fourth metatarsal is reached

2

Incise the subcutaneous tissue in line with the skin incision

  • use cautery to cauterize any crossing vessels for hemostasis

3

Identify the peroneal tendons

  • leave them undisturbed in there sheath
H

Deep Dissection

1

Identify anatomical structures

  • identify the sural nerve
  • identify the origin of the extensor digitorum brevis and the sinus tarsi fat pad

2

Elevate the EDB and Sinus Tarsi fat pad together as one flap

  • leave a small cuff of tissue proximally for reattachment of the flap

3

Identify and release the talocalcaneal ligament

  • this allows better exposure of the joint surfaces and the middle and anterior facet
I

Preparation of Arthrodesis Site

1

Visualize the lateral aspect of the subtalar joint

  • use a rongeur to remove any remaining soft tissues

2

Remove articular cartilage

  • use a straight curette or chisel to remove cartilage from the lateral half of the inferior talus and superior aspect of the calcaneal facets
  • insert a lamina spreader and remove the remaining medial articular cartilage

3

Create a vascular channel

  • use curettes and osteotomes to create bleeding subchondral bone
  • use a 2.0 mm drill to create small perforations in bone
  • these channels aid in the fusion

4

Compress bone together to assess contact of surfaces

5

Reattach the extensor digitorum brevis to its origin

  • if bone graft is inserted reattach tendon after insertion of graft
J

Harvesting and Placement of the Tibial Bone Graft (optional)

1

Create bone window

  • make a 1 cm incision distal to the distal aspect of the tibial tubercle and 1 cm lateral to the anterior tibial crest.
  • incision should be 4 cm long
  • divide the fascia over the anterior compartment musculature in line with the skin incision
  • elevate the muscle and the periosteum over the anterolateral face of the tibia using a periosteal elevator to expose the anterolateral cortex
  • create a 1 by 1 cm square or elliptical window in the center of the anterolateral face

2

Remove cancellous graft

  • insert a curette into the window and remove the cancellous graft
  • seal the window with the previously removed bone plug

3

Perform layered closure

  • perform a layered closure of the fascia, subcutaneous tissue and the skin

4

Place retrieved graft into the subtalar joint

  • make sure to place graft within 30 minutes of harvest
K

Alignment and Final Fixation

1

Place guidepins under fluoroscopy

  • create 1 cm incision at the apex of the heel for insertion of the guidepin

2

Place ankle in 7 degrees of valgus

  • assess alignment with radiographs
  • use kwire for provisional fixation

3

Place guidepin

  • use the Harris heel and lateral views to drive guidepin through the tuberosity, across the subtalar joint and into the talar neck.
  • make a second 1 cm incision just medial to the anterior tibialis tendon
  • use the Harris heel and lateral views to drive guidepin through the dorsomedial aspect of the talar neck across the subtalar joint into the posterior calcaneal tuberosity

4

Place cannulated screws with short threads

  • insert a 6.5 or 8 mm large fragment cannulated lag screws after minimal countersinking
  • repeat the procedure for the second guidepin except use a small fragment cannulated screw
  • this screw is usually 3.5 to 4.0 mm
  • depth of this screw is best judged by axial view of the calcaneus

5

Confirm hardware position

  • obtain final fluoroscopic images to ensure proper screw position
L

Wound Closure

1

Irrigation, and hemostasis

  • ensure hemostasis using cautery

2

Superficial closure

  • use 3-0 nylon horizontal mattress sutures for skin

3

Deep closure

  • use 2-0 vicryl for the subcutaneous layer

4

Dressing and immediate immobilization

  • place in well padded non-weightbearing short leg plaster cast
  • split cast in recovery room to allow for post op swelling
Postoperative Patient Care
 

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