Transtibial Problem Solving

Question 1

Provide two functions of the PTB socket.

Answer 1

• Load the weight tolerant areas
• unload the pressure sensitive areas
• provide total contact
• maintain ML stability at mistance

Question 2

Name the differences between the PTB socket and the TSB socket.

Answer 2

• The TSB distributes pressure globally.
• The PTB is modified by removing plaster over the weight tolerant areas.
• The PTB is modified by adding plaster over the pressure sensitive areas.

Question 3

What gait deviation would you expect to see in a transtibial patient with weak quadriceps?

Answer 3

Abrupt and uncontrolled knee flexion at loading response.

Question 4

How would you reduce excessive knee flexion at loading response in the transtibial patient?

Answer 4

• move foot anterior
• reduce socket flexion
• lower shoe heel height
• soften foot heel durometer
• soften the plantar flexion bumper
• select smaller foot if shoe prevents prosthetic heel cushion compression

Question 5

Relatively insetting the foot on the transtibial prosthesis, increases pressures in what areas of the socket?

Answer 5

Proximal - Medial

Distal - Lateral

Question 6

What are possible causes of excessive anterior distal tibial pressure in the prosthetic socket?

Answer 6

• Insufficient socket ply worn
• excessive socket flexion
• insufficient relief in PTB socket

Question 7

Patient complains of tingling and numbness of the transtibial residual limb while ambulating in a PTB socket. What are the possible causes?

Answer 7

• Peroneal nerve impingement causes by incorrect fibular head relief
• patient dropping too deep into the socket
• Claudication
• Tight proximal suspension

Question 8

Provide rationale/indications for PTB leather cuff suspension.

Answer 8

• standard length residual limbs
• good ML and AP stability
• durable
• easily adjustable

Question 9

Patient reports that his transtibial prosthesis feels too long. What would you check to evaluate this problem?

Answer 9

• sock ply, if too many
• prosthetic limb height
• is suspension appropriate?
• assess trunk lean while ambulating in the coronal plane
• check for heel wedge in shoe
• verify that foot matches shoe
• evaluate the vertical shock pylon travel

Question 10

What would you consider in the prosthetic socket design to accommodate for longitudinal growth of the transtibial pediatric patient?

Answer 10

• onion skin lamination (multiple removable layers)
• pelite liner
• distal end pad
• fit with multiple ply socks

Question 11

What prosthetic design would you use for a transmetatarsal amputation to reduce forces on the anterior aspect of the limb?

Answer 11

• accommodative insert with toe filler redistributes plantar pressures
• steel shank provides push off
• rocker bottomed shoe problems transfers forces off the distal limb