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1. Extension prosthesis

2. Objectives
• Problems associated with shortening for
prosthetic/orthotic management.
• Socket design criteria

3. • Congenital lower-limb deficiencies, which have not
been converted by amputation, usually present with
shortening as well as deformity and joint defects.
• It is normal practice to equalize the length by the use
of a extension prosthesis, prepared from a cast, which
is attached to a platform mounted above appropriate
prosthetic components.

5. • The provision of a prosthesis for a patient with a
congenitally shortened lower limb frequently presents
more problems than that for the more commonly
encountered amputee.
• The presence of a reasonably normal foot, although
capable of load bearing, may give special difficulties.
• Often the proximal joints are inherently unstable and
will require the support of a total contact socket, yet
the relatively large foot produces problems of access
to such a socket.

6. Socket design criteria
a) If the foot can take weight on the heel pad and also
on the heads of the metatarsals, then suitable areas in
the socket should be provided to preferentially stress
them.
• The unstable proximal joints will require the general
support of a total contact socket to maintain
alignment.

7. b) The foot will usually be held in an equinus position
within the socket.
• A system of forces must be provided to hold the heel
pad on its seat.
c) Provision must be made to allow the foot to gain
entrance to the socket yet retain the support of total
contact.

8. d) Since ankle movement will be lost within the socket
an attempt must be made to provide this function
prosthetically.
e) The appearance of the finished limb must be
acceptable cosmetically especially when fitted to the
young and socially active.
f) The limb must be durable without being excessively
heavy.

9. Review Questions
• Congenitally shortened lower limb presents more
problems than that for the more commonly
encountered amputee. (T/F)
• The proximal joints are inherently stable in congenital
shortening of lower limb. (T/F)
• The foot is held in an equinus position within the
socket. (T/F)
• The extension prosthesis must be durable without
being excessively heavy. (T/F)

10. Reference
• H. J. B. DA Y and J. WRIGHT, A system of extension
prostheses, prosthetics and orthotics international,
1977, 1, 8-12.
• T. J. C. HARTE , An alternative design of extension
prosthesis, prosthetics and orthotics international,
1987, 11, 90-92.
• R. R. HIRONS etal, The prosthetic treatment of lower
limb deficiency, prosthetics and orthotics
international, 1991, 15, 112-116.

11. Thank You