Preoperative Evaluation
The size of the fingernail is compared with that on the unaffected side or,
in the case of bilateral involvement, that of the index finger. Both digits of
the bifid thumb are carefully examined for joint mobility and stability. A
true anteroposterior radiograph of the thumb is required to identify the type
of bifurcation and to assess the bone size and the angulation of the joint. We
use the Wassel classification, which is based on the branching level of the
bifid thumb6. The
modified Bilhaut-Cloquet procedure is indicated for Wassel type-II and III
polydactyly, in which the bifid thumbs are symmetric and their nail size is
less than two-thirds of that of the normal contralateral thumb, or smaller
than the index-finger nail in patients with bilateral thumb involvement.
The family should be informed that a combination of digits will never
produce an identical match to the normal thumb, and it is not possible to make
a thumb with the same nail length as that on the normal side when the initial
nail lengths of the duplicated thumb differ from that of the normal thumb.
Patient Positioning and Preparation
After the administration of general anesthesia, the patient is placed
supine on the operating table and a pneumatic tourniquet is placed around the
arm. The upper extremity is prepared with standard antiseptic solutions and
draped. Special care is taken to ensure that the antiseptic solution does not
soak the cotton padding underneath the tourniquet because it may seriously
burn the fragile skin of the child. The other hand should be readily available
for comparison when necessary during the operation.
Modified Bilhaut-Cloquet Procedure
The modified Bilhaut-Cloquet procedure differs from the originally
described method because it is an extra-articular procedure; the
interphalangeal joint is reconstructed with tissue from one thumb, and the
other thumb contributes only part of the distal phalanx for stability. Because
it is not necessary to approximate the articular surface of the distal
phalanx, the nail bed can be sutured more precisely according to the natural
curve of the nail to minimize nail plate deformity
(Fig. 1).
An illustrative case of a ten-month-old girl with type-II thumb polydactyly
is shown (Figs. 2 and
3).
Figure 4-A shows the incision
drawn with a marking pen to demonstrate the parts of the soft tissue to be
removed. A triangular skin flap on the distal part of the pulp is designed to
prevent scar contracture and to make a smooth contour of the reconstructed
pulp (Fig. 4-B).
Under tourniquet control, the nail plates are removed with use of a small
elevator and a mosquito clamp (Figs. 5-A
and 5-B). The removed nail plate is preserved in saline solution
so that it can be used later as a temporary splint for the reconstructed nail
bed. Along the incision line, soft tissues, including skin and nail bed, are
removed (Fig. 6). The bases of
the two distal phalanges are carefully separated with use of a number-15
scalpel (Fig. 7). The thumb
with the greater range of motion of the interphalangeal joint is chosen to
become the main articulating digit (the radial side in the illustrative case),
which contains the articular surface, the physis, and a major part of the
distal phalangeal bone with the overlying nail bed. The thumb with less motion
of the interphalangeal joint (the ulnar side in the illustrative case) is made
into a fillet flap containing a minor part of the distal phalangeal bone
supporting the incised nail bed and the collateral ligament attached to the
proximal phalanx (Figs. 8-A and
8-B). The remaining phalangeal bone of the fillet flap is trimmed
with a small rongeur to better approximate the nail bed to that of the main
digit. The ulnar tuft of the main digit is also trimmed with a rongeur to
better approximate the nail beds (Fig.
9). The fillet flap basically contains the digital neurovascular
structures; thus, sensation of the pulp and nail bed can be preserved because
the nail bed is supplied by the most distal branches of the volar radial and
ulnar digital nerves and the pulp is supplied by dorsal branches of the volar
radial and ulnar digital nerves as well as the most distal extent of the
dorsal radial digital nerve
branches7.
The two distal phalangeal bones do not need to match exactly or even have
intimate contact because in most cases they will eventually fuse to become a
single bone. One or two transverse Kirschner wires, or a spinal needle if the
thumb is very small, can be used to manipulate the tufts to make the combined
nail bed look more natural (Fig.
10). The contour of the nail bed can be adjusted—for
example, made more rounded—by using the wire or needle as a joystick
(Fig. 11). To make one smooth
semicircular nail bed in the axial plane, slight axial rotation is required
because attaching two semicircular nails in a transverse plane alone creates a
so-called seagull deformity (Fig.
12). The nail fold and the nail bed are repaired with 8-0 nylon
sutures. Overly tight suture of the nail bed results in a prominent
longitudinal ridge. To avoid this ridge, the sutures should be tied under only
slight tension so that a small longitudinal slit can be observed along the
suture line (Fig. 13). The
nylon sutures are not removed later. The sutures are noticeable on close
observation at first but usually not after the passage of time, as their black
color eventually becomes faint.
With our modified technique, no attempt is made to compress the distal
phalangeal bones, so contouring of the combined nail bed is much easier. This
concept of osteosynthesis does not cause any problem during the healing
process, as ultimately there is remodeling of the distal phalanx.
The pulp skin anteriorly and the other skin are closed with 6-0 chromic
sutures. Then joint stability is tested, and, if required, an additional
transarticular Kirschner wire can be driven from the tip of the thumb across
the interphalangeal joint to stabilize it. One of the removed nails is then
placed on the new nail bed, and a stabilizing suture is placed at each side of
the nail (Fig. 14).
Alternatively, an artificial nail of normal size can be inserted to facilitate
remodeling of the nail bed.
In a type-III deformity, the extra thumb is osteotomized at the bifurcation
level and excised except for the distal bone fragment supporting the nail bed
and fillet flap. When the angular deformity of the interphalangeal joint is
>20°, a corrective closing-wedge osteotomy is performed at the proximal
phalanx of the retained thumb, and the osteotomy site is held by advancing the
transarticular Kirschner wire (Fig.
15).
Depending on the age of the patient, a short or long-arm thumb spica cast
is applied, with the long-arm cast used for children under five years of age.
The cast and the Kirschner wires are removed four to six weeks after the
surgery.
The time until solid osseous union of the distal phalangeal osteosynthesis
is seen radiographically and can range from four months to as long as a year.
However, with removal of the transverse Kirschner wire at four to six weeks
postoperatively, osseous healing is usually adequate for stability without
pain, and remodeling of the distal phalanx occurs with time
(Figs. 16-A through 16-E).
This technique cannot make a thumb with the same nail length as the one on
the normal side when the initial nail lengths of the duplicated thumb differ
from that of the normal thumb. Although a step-off of the lunula is
unavoidable in that case, trimming of the nail plates can make this nail
length discrepancy less prominent.
CRITICAL CONCEPTSINDICATIONS:The indication for the modified Bilhaut-Cloquet procedure is a Wassel
type-II or III polydactyly, in which the bifid thumbs are symmetric and their
nail size is less than two-thirds of that of the normal, contralateral thumb,
or smaller than that of the index finger in patients with bilateral
involvement.CONTRAINDICATIONS:The modified Bilhaut-Cloquet procedure is contraindicated for patients with
asymmetric bifid thumbs; ablation of the smaller thumb or use of only its soft
parts can obtain better results in such patients. Type-I polydactyly does not
require this modified technique because the bifid distal phalanges can be
combined with use of the original technique without violating the distal
interphalangeal joint. Type-IV and other polydactylies involve the
metacarpophalangeal joint, and the results of the combination operation are
usually poor in such cases.PITFALLS:A triangular flap created at the distal part of the pulp can prevent scar
contracture.During approximation of the two distal phalangeal bones, slight axial
rotation is required because attaching two semicircular nails in a transverse
plane alone creates a so-called seagull deformity.The nail bed is repaired under slight tension, without overlap of the
underlying matrix, and this tension suture can prevent the formation of a
prominent nail ridge.AUTHOR UPDATE:There have been no changes in the surgical technique since the time of
publication of the original paper.
CRITICAL CONCEPTS
INDICATIONS:
The indication for the modified Bilhaut-Cloquet procedure is a Wassel
type-II or III polydactyly, in which the bifid thumbs are symmetric and their
nail size is less than two-thirds of that of the normal, contralateral thumb,
or smaller than that of the index finger in patients with bilateral
involvement.
CONTRAINDICATIONS:
The modified Bilhaut-Cloquet procedure is contraindicated for patients with
asymmetric bifid thumbs; ablation of the smaller thumb or use of only its soft
parts can obtain better results in such patients. Type-I polydactyly does not
require this modified technique because the bifid distal phalanges can be
combined with use of the original technique without violating the distal
interphalangeal joint. Type-IV and other polydactylies involve the
metacarpophalangeal joint, and the results of the combination operation are
usually poor in such cases.
PITFALLS:
A triangular flap created at the distal part of the pulp can prevent scar
contracture.During approximation of the two distal phalangeal bones, slight axial
rotation is required because attaching two semicircular nails in a transverse
plane alone creates a so-called seagull deformity.The nail bed is repaired under slight tension, without overlap of the
underlying matrix, and this tension suture can prevent the formation of a
prominent nail ridge.
A triangular flap created at the distal part of the pulp can prevent scar
contracture.
During approximation of the two distal phalangeal bones, slight axial
rotation is required because attaching two semicircular nails in a transverse
plane alone creates a so-called seagull deformity.
The nail bed is repaired under slight tension, without overlap of the
underlying matrix, and this tension suture can prevent the formation of a
prominent nail ridge.
AUTHOR UPDATE:
There have been no changes in the surgical technique since the time of
publication of the original paper.