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THE SURGICAL AND PROSTHETIC MANAGEMENT OF PROXIMAL FEMORAL FOCAL DEFICIENCY

(Note from PFFDvsg Webmaster: Due to limited disk space
and scanning problems, the Figures referred to in this document are not available
online. My apologies for the inconvenience - hope to get them online
soon.)

This is Section 4 of 5 from PFFD: A Congenital Anomaly,
National Academy of Sciences, 1969
.

JOHN E. HALL, M.D., F.R.C.S.(C)

DIETRICH BOCHMANN, C.P.O.(C)

The Surgical and Prosthetic Management of

PROXIMAL FEMORAL FOCAL DEFICIENCY

Proximal femoral focal deficiency is a complex deformity which can affect
one or both lower extremities in varying degrees. Other congenital anomalies
are frequently associated with the condition. There is no single approach
to treatment that can be applied to every patient. Each must be assessed
individually, as the problem may be functional in one child. and merely a
matter of cosmesis in another. When treating patients with this condition,
one must be prepared to use all modalities, including surgery and special
prosthetic fitting, if optimal appearance and function are to be provided
for these patients.

When both lower extremities are involved the condition generally tends to
be more severe, and one of the major difficulties encountered is the extreme
loss of height. This problem of short stature is accentuated by the fact
that there is usually a severe hip-flexion deformity with the short femur
lying almost parallel to the ground when the child is standing. These children
have a waddling-type gait, but it is usually very effective, although their
bodies are close to the ground. The prime difficulty is one of cosmesis and
the physician is often forced into a position where he must choose between
appearance and function. By the use of braces which keep the thigh segment
and the shank in line, it is possible to add considerable height to the child,
but this treatment results in considerably decreased agility (Figures 1-A
and 1-B). Even more height can be added by the use of extension prostheses
which keep the knees fairly straight and add height by a segment below the
feet, either with or without a knee joint. Through the use of these prosthetic
extensions the child can be brought up to normal height, but activities are
greatly curtailed, and the final choice of management procedures in this
type of patient will often lie with the child himself and with the parents.

When only one leg is affected. the main problem is one of discrepancy in
length of the legs, although hip instability can be an added problem, depending
on the configuration of the upper end of the femur (1). In this group of
children. provision of a prosthesis is usually indicated. Whether or not
any type of surgical intervention is warranted will depend on the amount
of leg-length discrepancy and the actual configuration of the hip and ankle
joints.

BILATERAL PROXIMAL FEMORAL FOCAL DEFICIENCY

Five children with severe degrees of this deformity are being managed through
the Amputee Clinic of the Ontario Crippled Children's Centre. An attempt
has been made to obtain a balance between appearance and function, recognizing
that increasing the height of these children to that of their peers may be
of little benefit if they are not mobile enough to play or even walk with
them. Before the age of four they are probably best left alone, but as school
age approaches both the family and the child may wish to try some type of
appliance which will make the child less obviously different from his or
her playmates.

Figures 2-A through 2-G and 3-A through 3-H illustrate types of devices that
have been used. These devices range from simple braces which hold the knees
straight to articulated extension prostheses having knee joints and proper
feet.

When bilateral proximal femoral focal deficiency is combined with a distal
anomaly, such as a fibular hemimelia and a deformed foot, consideration may
then be given to surgical conversion (perhaps by a Syme's-type operation)
to make fitting easier and more efficient. This type of approach should only
be used, however, for a child whose deformities do not allow him useful
ambulation without his prostheses. As stressed above, no prosthesis can replace
the agility these children possess with their short extremities, providing
their feet are plantigrade. Even if extension prostheses are provided, children
will usually remove them within the confines of their own home, and nothing
should be done surgically to deprive them of this possibility.

Figures 4-A through 4-E depict a young girl with bilateral PFFD with which
were associated hypoplastic tibiae and severe clubfeet (partially corrected).
Nonprosthetic ambulation was impossible and the malformed feet made prosthetic
Fitting difficult. Following bilateral Syme's amputations, prosthetic fitting
was simpler and more cosmetic, while function without the prostheses was
unaffected.

Figures 5-A and 5-B illustrate the treatment of a boy with a unilateral PFFD
and an amelia on the opposite side. Independent ambulation was attained with
a Canadian hip disarticulation prosthesis, extension brace, and special crutches.

In all five of the patients illustrated, the hip deformity was a severe one,
and no surgical reconstruction of the hip joint was undertaken. When devices
were provided, the hip instability was managed by an ischial shelf on the
prostheses.

As the children in this group approach the end of their growth years,
consideration should be given to the performance of a knee arthrodesis to
overcome the hip-flexion deformity, and to overcome some of the height deficit
which is caused by the squatting stature associated with the PFFD.

UNILATERAL PROXIMAL FEMORAL FOCAL DEFICIENCY

A knowledge of the anticipated final leg-length discrepancy is probably the
best guide to the type of management that will be most appropriate for these
children. In this regard the work of Amstutz and Wflson (2) on predictive
measures is most valuable. In reviewing a large number of cases, they have
observed that there is a constant percentage of retardation of growth on
the involved side, so that a knowledge of the actual amount of discrepancy
compared to the length of-the normal limb will permit calculation of an
approximate amount of discrepancy one is likely to encounter at the completion
of growth.

By the time a child is approximately three years of age, one should be in
a position to tell how much of a problem this difference in leg length is
likely to be, and plan a rational form of treatment based on this knowledge.

If the predicted difference is 3 in. or less, then the discrepancy can be
best managed by the standard methods of leg equalization, including lifts
or raises on shoes, epiphyseal arrest or leg shortening on the long side,
and attempts at growth stimulation or mechanical lengthening on the involved
side. Since the deformity is relatively mild in this group of patients, the
foot is usually a good one and the hip is not too badly involved. Hence,
a reasonable result can be anticipated without the need for prosthetic
management.

If the final discrepancy is expected to be in excess of 5 in.. then this
child will surely present a prosthetic problem. For children in this group,
one will have to decide at some time whether or not some type of surgical
conversion will be worthwhile. When the discrepancy is likely to be between
3 and 5 in., then, as in many other areas of orthopedic surgery, one is dealing
with a borderline situation, and decisions must be based on surgical and
prosthetic judgment and discussion of the problem with the parents and with
the child, if he is old enough to participate.

Prosthetic management may entail as small an item as a simple shoe raise,
which is usually all that is necessary for the mild case from the latter
part of the first year through the second year of life. Other types of raises
varying from the O'Connor boot to the simple extension prosthesis may be
used according to the age and condition of the child.

Figures 6-A and 6-B show a young boy with a typical unilateral PFFD without
associated defects. At the age of 18 months he was fitted with an O'Connor
boot, and raises were added to the sole as he grew older. Eventually, he
was provided with a simple plastic laminate extension prosthesis (Figure
6-C). Figure 7 depicts another child fitted with an O'Connor boot.

A more pronounced leg-length discrepancy in a young girl is shown in Figures
8-A and 8-B. She was wearing an extension brace (Figures 8-C and 8-D) when
first seen at the clinic.

Another young boy with considerable leg-length discrepancy was fitted with
an extension prosthesis without knee joints at a very early age (Figures
9-A, 9-B, and 9-C). Still another, whose anomalous right foot was at the
level of the normal left knee, was provided with knee joints very early in
his prosthetics career (Figures 10-A and 10-B).

In older children whose parents reject surgical intervention, a reasonably
satisfactory extension prosthesis can be provided (Figures 11-A and 11-B).
However, when parental and patient agreement can be secured, removal of the
foot and fitting with a knee-disarticulation-type prosthesis is perhaps an
even more satisfactory procedure for such patients (Figures 12-A and 12-B).

ROTATION OSTEOTOMY

There are many types of surgical management programs which may be used for
the group of patients with 5 in. or more of leg-length discrepancy, including
removal of the foot and then fitting the patient as a knee-disarticulation
amputee. It is in this group that one may also consider a surgical rotation
of the limb through 180 deg, so that the ankle joint can be used to operate
the knee joint of a prosthesis.

This principle of rotating the foot was first used by Borggreve in 1930 (4)
in a patient with a short femur secondary to an infection. Rotation was performed
through the shaft of the femur.

In 1950, Van Nes described three cases in which he had rotated congenitally
short lower extremities, so that the ankle joint could be used to give active
control of the knee joint (5). The ages of these patients were one, nine,
and fifteen years, respectively. In the youngest patient, part of the rotation
was performed through a pseudarthrosis at the upper end of the femur, and
the rotation was completed through a knee arthrodesis. In the nine-year-old,
part of the rotation was performed through a knee arthrodesis and the remainder
was subsequently obtained through a tibial rotation osteotomy. In the third
child, all of the rotation was performed through a knee arthrodesis with
sufficient resection of the lower end of the femur and the lower end of the
tibia to effect the rotation safely. In each of these patients the final
level of the ankle joint approximated the level of the opposite knee joint,
and the patients learned to control the knee of the prosthesis very effectively.

There is little to add to the original description of this procedure, except
that the main problem is a prosthetic, not a surgical, one. The surgical
procedures are not complicated, but the prosthetics fitting is difficult,
and it requires the services of a skilled prosthetist, particularly in the
design of the foot socket and knee joint.

When considering, whether or not to advise this type of procedure, one must
realize that it has both advantages and disadvantages. The extension prosthesis,
while giving quite an effective gait, is an awkward device, which will not
bend at the knee either during walking or sitting. The principal advantage
of the rotation type of osteotomy is that with it the child can obtain some
control of the prosthetic knee unit and can bend his or her knee on sitting,
kneeling, and bicycle riding.

One disadvantage of the rotation osteotomy is that the rotated foot presents
a rather strange appearance when the prosthesis is off, and since one usually
shortens the limb while it is being rotated, the patient's function without
the prosthesis is typically diminished. The child is then usually put into
a position where it is necessary for him to wear his prosthesis full time
after the rotation has been accomplished. The appearance of the stump can
be improved by removal of all of the toes, but this gain must be balanced
by the loss of power in the stump, and also a loss of position sense and
the feeling the child has that he can grip his prosthetic socket with his
toes. The argument in favor of removing the toes is that fitting becomes
slightly easier, since the stump has a rounded contour.

A further problem which may arise if the child has not completed his growth
by the time of his rotation is that the twisted musculature will tend to
gradually derotate the leg,. Of the nine patients who have had this procedure
performed before the age of 12 years, four have already required repeat rotation
osteotomies within three years of the original procedure, and the remainder
will probably require rerotation also (Figures 13 and 14).

The necessity of repeated osteotomy could be avoided by waiting until the
end of growth, but it may well be that the advantage of learning to use the
ankle as a knee joint at an early age outweighs the relatively minor surgery
involved, even if it has to be repeated once or twice before the end of the
growth years.

The rotation can be accomplished at almost any level in the leg, and the
final position, both with regard to rotation and level of the knee joint,
is usually obtained by arthrodesis of the knee. This procedure is also valuable
in overcoming the hip flexion deformity found in the more severe types of
hip involvement.

Nineteen patients with unilateral proximal femoral focal deficiencies are
being followed at the Amputee Clinic at the Ontario Crippled Children's Centre,
and the nine patients who were selected for rotation osteotomy were those
deemed to have the best chance of benefitting from this procedure, and whose
parents agreed to have it performed.

Figures 15-A through 15-D show the anatomical and prosthetic status of a
young boy before and after rotation osteotomy.

Figures 16-A through 16-G illustrate another case of rotation osteotomy in
which the toes were removed to improve the appearance of the stump. The excellent
gait achieved by this child is shown in a series of frames from her film
clip (Figure 16-H).

PROSTHETIC FITTING

As previously mentioned, one of the decisive factors determining whether
or not a rotation osteotomy will be successful is the level of prosthetic
management. A description of procedures follows:

CASTING

When the cast of a Van Nes rotation-osteotomy stump is being taken, two areas
of weight-bearing are defined-the ischium and the heel. Once the full-length
stump sock (cotton stockinette stitched in a half-moon shape at one end)
is applied, the top of the sock is held firmly by an assistant. The
plaster-of-Paris wrapping begins around the ischium and dium and extends
distally about three inches and proximally two inches to the ischial tuberosity.
At this point no further casting should be done until this section has been
molded into a quadrilateral shape. The technique of shaping by hand can give
satisfactory results, or a casting device* can be used. While the assistant
holds this quadrilateral socket cast against the ischium to ensure constant
seating, the knee flexion which is present in many cases is now corrected.

With the knee held in its fullest extension, casting is continued distally
from the shaped proximal section to just above the ankle and then is taken
back to connect again with the quadrilateral-shaped section above. The assistant
now moves to hold the foot in maximum plantar flexion for completion of the
wrapping. A shelf, similar to the PTB shelf, is shaped on the plantar side
of the calcaneus by simply applying pressure with the index finger on the
long plantar ligament. Finally, plumb lines should be marked for reference
on the lateral and anterior surfaces with the patient standing. When filling
the cast to make the male mold, the holding pipe should be set parallel to
these lines. This is necessary so that the holding pipe can be used as a
reference line to transfer the plumb lines to the laminated socket later.
The distance from the distal end of the cast to the floor should also be
determined and the space available for filler blocks and/or the alignment
jig* and the SACH foot noted. This is done by placing blocks under the cast,
while the patient is still standing.

The male model is modified as required. Areas are built up where pressure
relief is desired. Reliefs for the toes and ankle and other bony prominences
are particularly important.

FABRICATION OF SOCKET

Lamination procedures require the use of one layer of Dacron felt and three
layers of nylon stockinette. Polyester resin* in a mixture of 70 percent
flexible (P43) and 30 percent rigid (P13) is used. Suction, by means of a
vacuum pump, is strongly recommended because of undercut areas where the
laminate has to be drawn into the shape of the cast.

ALIGNMENT

Plumb lines on the cast should be transferred to the laminate using the holding
pipe as a reference. The socket should be set into a filler block in accordance
with these plumb lines. If space permits, a BK adjustable pylon is used;
if the length is too short to accommodate an adjustable unit, filler blocks
are used.

The axis of the mechanical knee joints is located 3/8 in. distai to the malleolus
on the lateral aspect of the stump. The knee joints are aligned and their
position marked on the socket.

The thigh socket can now be separated from the foot socket and trimmed. Trim-line
details are shown in Figure 17.

The hinges are installed temporarily in the locations previously marked.
Further trimming may be necessary on the distal end of the thigh socket to
allow free passage of the foot into the foot socket. Anteriorly the thigh
socket is trimmed on its distal end to provide clearance for the heel tendon.
If insufficient space is available to allow passage of the foot, a hinged
panel is installed posteriorly on the distal end of the thigh socket.

To stabilize the anatomical knee within the thigh socket and to supply some
degree of suspension, a 1 1/2-in.-wide Velcro strap may be used. This strap
is drawn through an aperture on the medial side of the thigh socket and passed
around the stump just above the patella so as to pull the stump posteriorly.
The strap continues through the lateral aperture, where it is fastened on
the outside of the socket.

A modified Silesian belt of 1 1/2-in. cotton webbing provides most of the
suspension. A piece of San-splint* 2 in. wide and 4 in. long is molded over
the opposite iliac crest, fitting around the anterior superior iliac spine
for control of rotation.

Two areas of weight-bearing are provided in this prosthesis. One is at the
ischial shelf, which is the primary source. the other is the long plantar
ligament shelf (heel pad).

To ensure a stable knee without active extension of the anatomical foot on
contact, the centers of knee hinges must be kept posterior to a plumb line
between the trochanter and the ankle of the SACH foot.

Initially, the first prosthesis is fitted shorter than the sound leg and
then lengthened according to the patient's progress during gait training.

Following completion of fitting and alignment procedures, final fabrication
of the prosthesis is carried out with emphasis on cosmesis (Figures 18-A
and 18-B). If a BK adjustable leg was used to obtain dynamic alignment (Figure
18-C), a transfer jig* is required in order to maintain alignment of the
foot and upper section of the prosthesis. If alignment was done using filler
blocks, these sections should be hollowed out to reduce the weight. In either
case, the calf section is built up with Micro-Spheres* or Hosmer Prosthetic
Foam. The lower halves of the knee hinges are fastened permanently to the
shank and a final lamination is applied to this part of the prosthesis. On
the thigh socket the upper halves of the knee hinges and the Silesian belt
are removed. The holes left by the screws plus the side apertures are filled
with wax. Final lamination of this section is carried out. Normally, no buildup
of the top socket is required.

After lamination, the prosthesis is reassembled. The upper halves of the
mechanical knee joints and the Silesian belt are riveted on after all the
wax has been removed.

Figures 19-A through 19-E show stump and prosthesis before and after Van
Nes osteotomy.

OTHER CONSIDERATIONS

Even when a good prosthesis has been supplied, the patient may still have
a poor gait because of hip instability, and consideration should be given
to reconstruction of the upper end of the femur in defects of Aitken's Types
A and B. During the early years of life it may appear that no femoral head
and neck are present; however, some hint can be obtained by determining whether
or not the acetabulum seems to be developing normally. If there is a good
acetabulum, then one can assume that a cartilaginous upper end of the femur
is also present and will eventually ossify. When it does, a varus deformity
of varying degrees of severity is seen.

Figures 20-A and 20-B and 21-A through 21-D demonstrate the type of deformity
and the result obtained by osteotomy in two of our patients in the unilateral
group. Two other patients also required an innominate osteotomy to render
the hips stable because of an associated acetabular dyspiasia.

In the patient with a very short distal femoral shaft only and no upper femoral
end, consideration could be given to fusion of this short shaft to the ischium
or acetabulum with 180 deg of rotation of the lower fragment in order to
use the knee joint as a hip and the ankle joint as a knee. This procedure
has been performed in only one patient in the series of Toronto PFFD cases
and that one has been done too recently for evaluation of the results.

SUMMARY

There are very many ways to approach the problem of the surgical and prosthetic
management of a child with proximal femoral focal deficiency. The experience
at the Amputee Clinic of the Ontario Crippled Children's Centre in Toronto
has been outlined.


*VAPC Casting Stand, available from U.S. Manufacturing Co., Glendale, Calif

*Berkeley Adjustable Below-Knee Jig, available through A. J. Hosmer Corp.,
Campbell, Calif.

*Polyester Resins, available through Rohm & Haas Company of Canada Ltd.,
West Hill, Ont.

*San-splint available through Smith & Nephew, Lachine, Que.

*Hosmer Vertical Fabricating Jig, available through A. J. Hosmer Corp., Campbell,
Calif.

*Micro-Spheres available through U.S.  Manufacturing Co., Glendale,
Calif.

BIBLIOGRAPHY

1. Aitken, G. T. Instructional Course Lecture, American Academy of Orthopaedic
Surgeons, 1967.

2. Amstutz, H. C., and P. D. Wilson. Dysgenesis of proximal femur (coxa vara)
and the surgical management. J. Bone Joint Surg. 44A: 1-24, 1962.

3. Bevan-Thomas, W. H., and E. A. Millar. A review of proximal focal femoral
deficiencies. J. Bone Joint Surg. 49A(7):13761388, 1967.

4. Borggreve, J. Kniegelenksersatz dutch das in der Beinlangsachse um 180
deg gedrehte Fussgelenk. Arch. Orthopad. Chir. 28:175-178, 1930.

5. Van Nes, C. P. Rotation-plasty for congenital defects of the femur (making
use of the ankle of the shortened limb to control the knee joint of a prosthesis.
J. Bone Joint Surg. 32B: 12-16, 1950.

This is Section 4 of 5 from PFFD: A Congenital Anomaly,
National Academy of Sciences, 1969
.