Technical Aspects of KAFO fabrication

Question 1

Where is knee center?

Answer 1

Halfway between medial tibial plateau and adductor tubercle.

Or lateral tibial plateau

Question 2

What is the ankle joint height?

Answer 2

Baseline to distal tip of medial malleolus.

Question 3

Where is proximal edge of the calf band located

Answer 3

20mm from the neck of the fibula.

Question 4

How much ankle joint clearance should you have?

Answer 4

5mm from each malleoli.

Question 5

How do you determine transverse plane rotation of the ankle ?

Answer 5

Align ankle joints to measurements of malleoli in the AP direction, Deflect medial malleolus anteriorly the difference in measurement + 3mm to accommodate for increased ankle diameter in the mechanical joint.

Only move lateral spring posteriorly if distance is more than 28mm.

Question 6

What happens with the ankle joint is above anatomical ankle axis?

Answer 6

• Will move distally with plantar flexion and dorsiflexion.
• Dorsiflexion: pressure anterior distally and posterior proximally.
• Plantarflexion: pressure posterior distally and anterior proximally.

Question 7

What happens with the ankle joint is below anatomical ankle axis

Answer 7

• Will migrate proximally with PF and DF.
• DF: pressure proximal anterior and distal posterior
• PF: pressure proximal posterior and distal anterior

Question 8

What happens when ankle joint is in front of the anatomical axis?

Answer 8

DF: move proximally. pressure anterior distal and posterior proximal.

PF: moves distally. pressure anterior distal and posterior proximal.

Question 9

What happens when ankle joint is behind anatomical axis?

Answer 9

DF: Moves distally.
Pressure anterior proximal and posterior distal.

PF: moves proximal.
Pressure anterior proximal and posterior distal.

Question 10

Where does the proximal border of the proximal thigh band stop

Answer 10

35m distal to perineum

Question 11

What happens when knee joint is too far anterior?

Answer 11

Brace migrates distally

Pressure on thigh: anterior distal, posterior proximal.

Pressure on calf band: anterior.

Question 12

What happens when knee joint is too far posterior?

Answer 12

Brace migrates proximally

Pressure on thigh band: Anterior proximal, Posterior distal

Pressure on calf band:
Posterior

Question 13

What happens when knee joint axis is too far superior?

Answer 13

Brace migrates distally

Pressure on thigh band:
anterior proximal
Posterior distal

Pressure on Calf band:
Anterior

Question 14

What happens when knee joint axis is too far inferior?

Answer 14

Brace migrates proximally

Pressure on thigh band:
Anterior distal and proximal posterior

Calf band: pressure in the calf.