Technical Note: An Alignment
Alternative for Spring Lite and Flex
Feet
Jeffrey S. Lutz, C.P.O.
The advantages that carbon fiber shank/
foot systems have over conventional prosthetic feet have been discussed at great
length since their introduction. Today it is
generally accepted that the Spring Lite and
Flex Feet can benefit almost all amputees,
regardless of their activity level.
Prosthetists working with these feet have
watched these systems evolve into dependable, cosmetic and extremely functional alternatives to more conventional prosthetic
fittings. There are presently several ways to
align the systems, including a customized
Flex Foot fixture and Otto Bock endoskeletal components that can be adapted to either
system. These alignment fixtures do work;
however, both are somewhat limited in the
alignment possibilities that the prosthetist
can achieve without rebonding the socket
and zeroing out the particular alignment instrument. We were forced to do this several
times at our facility.
The protocol for an alignment fixture to be
used with these systems is as follows:
- Medial-Lateral adjustment (not incremental)
- Anterior-Posterior adjustment (not incremental)
- Rotation (wide range)
- Flexion-Extension (wide range)
- Adduction-Abduction (wide range)
- Ability to be removed in transfer for
weight savings
The alignment device that our facility is
using is the Staros-Gardner unit, manufactured by USMC (part #P12-400-OOO). This
device provides all the above criteria and has
withstood the test of time as a reliable alignment tool.
The bottom portion of the Staros-Gardner
unit is pre-drilled and tapped for the same
Otto Bock bolt pattern that both the FlexFoot and Spring-Lite systems use. The
Staros-Gardner is bolted directly to the top
of the attachment plate supplied with the
foot.
The below-knee socket is then bench
aligned on the foot, using a 1" wood block on
top of the Staros-Gardner unit that has been
recessed to accept the socket approximately
5/8". It is important that the wood block be
secured with #8 wood screws in all of the
holes provided.
The entire alignment system (including recessed wood block) will occupy approximately 1-3/8", therefore, when ordering the
foot, 1-3/8" should be subtracted from the
overall length of the shank.
The dynamic alignment is done according
to the foot manufacturer's guidelines and accepted prosthetic practice. Using this technique, the alignment potential is virtually
unlimited, and the prosthetist has the ability
to "go a little farther than needed" in each
plane to ensure that the best possible alignment has been achieved.
The prosthesis is then transferred, replacing the Staros-Gardner unit with a cut-down
Otto Bock wood block (part #5R1), and the
socket is foamed in place.
The finished prosthesis is at the patient's
optimal alignment and its weight is minimal.
Jeffrey S. Lutz, C.P.O., is with I.E. Hanger,
Inc., 417 Evangeline Twy., NE, Lafayette, LA
70501.
|
