Question

For a male patient of average build and a limb diameter of 14 cm walking while wearing a patellar tendon bearing prosthesis, would you expect there to be more displacement between the residual limb skin and socket or between the bone and socket?

Answer 1

The socket was made according to the size because it doesn't have the capacity as a foot to wear weight, so the size of the socket matters in rehabilitating the patient with socket,

The patellar tendon bearing socket was designed in 1950, it was also designed according to the pain bearing capacity of the limb and the tissues, pressure should not be more than patients tolerance, it is also designed to make a patient walk with the prosthesis without pain.

It was further noted that during placement of the socket the soft tissues are displaced and socket is being fitted, and socket comes directly in contact with the bony area and causes less pressure over the skin and the soft tissues, due to the bony area that is covered by the socket causes more pressure over bone and causes more pain on the bony part.

The failure of producing the right prosthesis is because of the improper training and the technique and also by putting plaster and the bandages in an inappropriate manner, therefore to reduce the pressure on the bone, Murdoch introduces the concept that uniform pressure should be applied on the residual limb by using fluid as a medium that was called Dundee socket.

Kristinsson uses the concept of air filled at the silicon socket, plaster wrap on the residual limb, but the most effective socket was the socket used on the principle of hydrostatic transfer of the load.

Hydrostatic principle of load transfer is only possible when volume in both the soft tissues and the residual limb is the same so that no displacement of tissues takes place and the closed system can be achieved.

More displacement between the residual limb and the prosthesis would not be expected as it may cause a fitting problem in future and complications may occur.

Point to be taken care of a prosthesis.

1. Fitting and alignment

Deviation of the gait is assessed by the physiotherapist due to the prosthesis.

2. Functioning of components of the prosthesis.

Teaching client regarding the technique of using prosthetic and to apply pressure minimally to avoid any further damage to the bone and the tissues involved in the prosthesis, correct gait training should be given to the client to use the prosthesis optimally.

3. Teach the client what to do when it is uncomfortable and also how to put the prosthesis.

As there is always a direct contact between the socket and the prosthesis if the proper fitting is not achieved then there is no use of the material that is used in making the prosthesis

The pin locking system should be used to keep the prosthesis at the right position, and also contact between the bone and the prosthesis should be made to achieve control over the gait cycle.

Proper mould should be made to fit the socket and proper measurement should be done while making the prosthesis,

More displacement means more in discomfort to the patient, less displacement can be cured later but more displacement between the bone and the socket will cause pain and the movement will be improper and also gait of the patient will be uncoordinated during the walk, improper distribution of the weight of the prosthesis can cause pain at the pressure sensitive areas of the stump,

Successful fitting of patellar tendon bearing prosthesis has good control over tissues which are soft and also helps in minimising pressure and distribution of the load at the weight-bearing site.