A transtibial amputation is above the foot but below the knee. These amputees have a very good chance of regaining normal mobility using a prosthesis.
There are two different types of transtibial prostheses: Patellar Tendon Bearing (PTB) prostheses, and Patellar Supracondylar (PTS).
The most common socket used in PTB design where all weight of the amputee is carried through the stump. The PTB socket contains soft liner and provides cushioning, although a hard socket is considered to be cooler.
Patellar Supracondylar (PTS) was developed in 1964 and is a modification of the commonly used PTB prosthesis. It encloses the patella in front and the femoral condyles medially and laterally.
The advantages of PTS as compared to PTB are:
- The need for suspension strap is eliminated
- Pistoning is reduced because of the closely fitted high enclosure about the condyles and patella
- Increased stability at the knee
- Pressure over the weight-bearing areas of the stump is decreased
- Shorter stumps can be fitted because of the high walls and increased contact areas
- Better cosmetic appearance