Technical Note: Recurvatum Sling
Robert A. Bangham, C.P.O.
Introduction
Various efforts to control genu recurvatum of the knee have been tried over the
years with different measures of success.
Some of the various attempts with which the
author is personally familiar are:
- Calf bands with a rigid prominence extending into the popiteal area
- Elastic adjustable criss-crossed straps
behind the knee
- A modified anterior knee pad mounted
posterior of the knee
- Calf/thigh bands mounted close to the
axis of the knee
The procedure described was taught to the
author in 1965 by Mr. Loren Jouett, C.P.O.,
Chicago, Illinois. Over the last ten years, the
technique has been refined with the central
fabrication department of Hittenbergers in
Northern California.
Since many of the patients seen by the
author are post-polio, the traditional leather
covered metal cuffs are used. In other types
of patients where plastic materials are used,
it is necessary to be more innovative.
Fabrication Technique
The basic design is a sling or hammock of
horse hide suspended in the posterior portion of the orthosis. It is soft and flexible in
the flexed position, but becomes taut like a
"drum head" when the knee goes into extension. For most style traditional KAFOs with
leather covered metal bands, the following
illustrated procedure should be easily adaptable.
When the metal components of the orthosis have been assembled and the leather
work is in a partially assembled state, determine the sling length and cut a paper template of the sling (Figure 1)
.
This is then transferred to a piece of horse
hide, taking care that the stretch of the leather does not run longitudinally the length of
the orthosis but from medial to lateral (Figure 2)
. The sling is lined and padded and the
proximal and distal edges are sewn to the calf
band and distal thigh band padding.
The distal thigh band padding is first assembled on the band with the distal seam
open. The proximal edge of the sling is
placed between the layers of the padding
(Figure 3)
and the seam is sewn shut (Figure
4)
.
Similarly, the calf band padding is assembled on the calf band with the proximal seam
open. The KAFO is held with the knee in a
partially flexed position and the distal edge
of the sling is assembled inside the proximal
seam of the padding. The position and length
of the sling are adjusted to take into account
the degree of tightness desired in full extension (Figure 5)
. The sling is temporarily secured to the padding in the desired position
with rubber cement and the assembly is sewn
(Figure 6)
.
The sling is trimmed to leave the joints
free, folded back over the uprights proximal
and distal of the joints and sewn to itself in
light equal tension (Figure 7)
.
In the future, the tension can be readjusted (to take into account stretching in the
leather) by cutting the stitches and repositioning the leather tabs.
The technique is adapted to plastic
KAFOs by reinforcing the proximal and distal edges of the sling with pieces of dacron
webbing glued between the layers of the
horse hide. The sling can then be riveted to
the proximal and distal shells and the leading
edges secured to themselves about the uprights in a manner analogous to that used on
a conventional metal KAFO.
While the design has been met with some
initial resistance on the part of patients, the
majority have become converts and quite
happy with its use.
Robert A. Bangham, C.P.O., is with Hittenbergers and resides at 67 West Lake Drive, Antioch, California 94509.
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