1564
CHAPTER 30
|
The Child with a Limb Deficiency
FIGURE 30-34.
An AP standing lower extremity radiograph of a
patient with PFFD after knee fusion. Neither the distal femoral or prox-
imal tibial epiphyses were removed at the time of fusion, resulting in
a residual limb that falls below the contralateral knee. Coupled with
the length required to fit a prosthetic knee joint (typically >7.5 cm),
this will result in a residual limb that is significantly too long for the
patient. Removal of the distal femoral epiphysis and physis at the
time of knee fusion is indicated except when the residual femur is
extremely short and the tibia is significantly short as well.
usually give enough limb length for successful prosthetic fit-
ting. Any additional length contributed by the femur is unnec-
essary and interferes with accommodating the knee joint in
the prosthesis. The author’s experience is that, in considering
patients with PFFD with or without fibular hemimelia, 90%
of children had at least 90% of the normal length of the tibial
segment. In the children where this was true, patients at the
time of knee fusion underwent excision of both distal femoral
and proximal tibial epiphyses and physes, and no residual limb
was too short to successfully fit with an above-knee prosthesis.
In some cases, with more pronounced tibial and femoral short-
ening, it may be advisable to remove neither or one epiphysis
and physis (171). Calculation of the anticipated length of both
limbs at maturity by means of the Green-Anderson growth
charts (Tables 30.2 and 30.3), as described earlier, will help
with the answer.
Fixation at the fusion site is often a rigid intramedullary
rod inserted from the proximal femur across the fusion site
into the distal segment, with an additional K-wire across the
fusion site to give the construct rotational stability. The patella
may or may not be excised during fusion. If it is excised, the
bone can be used as graft at the fusion site. There have been
a few cases reported of late-onset patellofemoral pain and
arthritis on radiographs in PFFD patients with knee fusions
and retained patellae (172). After surgery, limb stability is
enhanced with a spica cast. The patient is usually ready for
prosthetic fitting in 6 weeks and for ambulation as soon as the
prosthesis is ready.
Amputation of the Foot.
With the knee fused, ablation of the
foot is desirable in most situations. One reason is to ensure
the residual limb will be short enough to accommodate an
internal knee joint when the child is older. The other reason
is that it becomes increasingly difficult to fit the growing foot
in a cosmetically acceptable socket. Whether or not a Boyd or
Syme amputation is performed is largely surgeon dependent,
and the relative merits of each procedure have been previously
discussed.
Van Nes Rotationplasty.
In the Van Nes rotationplasty, the
limb is rotated 180 degrees, predominantly through the knee
arthrodesis, with some additional rotation through the tibia
if necessary. The goal is to have the ankle/hindfoot complex
of the short limb at the level of the knee on the long limb at
maturity. The foot now functions like the residual tibia in a
below-knee amputation, thereby allowing the patient to func-
tion more like a BK amputee than one with a knee disarticula-
tion (Figs. 30-35A–D). Sufficient ankle and hindfoot flexion
and extension, as well as ankle stability and alignment, are nec-
essary for this type of treatment.
The rotationplasty was first described in 1930 by
Borggreve (173), for acquired traumatic limb-length discrep-
ancy. Van Nes (174) later used the procedure for three cases
of congenital deficiency of the femur. Initial reports of rota-
tionplasty for treatment of PFFD by Kostuik et al. (175) and
Torode and Gillespie (176) have been followed by more recent
reports by Friscia et al. (177) and Alman et al. (178).
The main complication of the procedure is either failure
to achieve sufficient rotation at surgery or subsequent derota-
tion with growth. Kostuik et al. (175) recommended waiting
to perform the surgery until the child was older. However, this
prevents the child from deriving the gait benefits for several
years. Subsequent reports have not found this to be so great a
problem. Also, derotation can be treated with revision surgery.
Even though the functional results of the surgery are
superior to that of an above-knee prosthesis wearer, parents
and physicians are sometimes reluctant to perform it because
of the cosmetic appearance of the foot pointing backward. It
appears, however, that this problem is overrated by medical
staff, compared to the patients themselves. Alman et al. (178)
found no difference in the perceived physical appearance
of children treated with rotationplasty, compared to knee
