Keywords
extensor apparatus - reconstruction - autograft - palmaris longus
Introduction
Injuries to the extensor apparatus of the fingers are very common due to its superficiality,
which makes it vulnerable to a traumatic event.[1] This apparatus, made up of tendons of the extrinsic musculature (tendon of the extensor
digitorum communis EDC), intrinsic (tendons of the interosseus and lumbrical muscles)
and the extensor aponeurosis (retinacular ligaments and covering of the extensor tendon),[2] is interconnected to perform the extension. The compromise of one or several of
these components, added to the chronic nature of the lesion, which is often accompanied
by retractions, contractures and adhesions,[3] results in a difficult approach with a high possibility of failure.
Chronic injuries, in turn, are accompanied by tendon defects that require reconstruction
techniques that lead to the use of tendon grafts. The reconstruction must be precise
since shortening by as little as 1 mm can result in loss of digital movement.[4]
We herein report a case of chronic injury of the extensor apparatus treated by reconstruction
with a palmaris longus (PL) autograft in a single surgical time.
Clinical case
A 29-year-old male who suffered a traffic accident, with a clinical history of open
fracture of the femur, open dislocation of the left forearm, amputation of the second
finger of the left hand, and multiple injuries to the back of the hand, was admitted
to the emergency department and then treated for fracture stabilization. Eight months
later, he came for an outpatient consultation due to the impossibility of performing
full extension of the third finger. Upon physical examination, he presented a 5-cm
long scar on the back of the third finger from the metacarpophalangeal (MCP) region
to the proximal interphalangeal region, complete limitation of the extension of the
interphalangeal joints, and complete extension of the MCP joint, leaving the finger
in the form of a claw in extension ([Fig. 1A]), with preserved finger flexion.
Fig. 1 (A) Claw deformity of the third finger in extension, skin lesions are also evident.
(B) Adherence of the EDC tendon to the proximal phalanx, allowing extension of the MCP
joint.
When carrying out the preoperative planning, the presence of the PL tendon was clinically
evaluated; once confirmed, the surgical procedure was carried out, after anesthetic
blockade and ischemia cuff, making a dorsal incision including the scar extending
sinuously and progressively from zones V to I of Verdan, finding rupture and adherence
of the ECD tendon at the level of the diaphysis of the proximal phalanx with the presence
of abundant fibrosis, alteration of the anatomy of the extensor zones III to V of
Verdan ([Fig. 1B]). The adhesion was released until the integrity of the EDC tendon began to be evident.
Then, the PL tendon graft was extracted through small incisions in the volar region
of the forearm, and the tendon graft segment to be used was calculated in extension
from the proximal end in Verdan zones V to I ([Fig. 2]). Then, with nylon 3–0 and the modified Kessler-type suture technique, tenorrhaphy
of the proximal region was performed, reinforcing the epitendon with nylon 5–0. Afterwards,
the graft was crossed under a remnant of the retinacular ligaments until reaching
the distal phalanx ([Fig. 3]). At the level of base of the distal phalanx, an oblique perforation was made with
a 1.5-mm drill bit, and the hole was crossed with an 18-G epidural needle. Then, 2
strands of 3–0 nylon previously attached to the holes of a button were passed through
the epidural needle, the needle was removed, and the strands were attached to the
end of the tendon. The distal end of the tendon was flattened by fixing the edges
with 5–0 nylon to the conjoined lateral bands. Subsequently, the distal interphalangeal
(DIP) joint was blocked with a 1.2-mm Kirschner wire. In the proximal region, at the
level of the metacarpal head, with the remaining tendon graft, a ligament was created
that mimicked the function of the sagittal band, and it was fixed to the capsule with
4–0 nylon. ([Fig. 4]). We proceeded to lavage with saline solution, skin synthesis, and placement of
antebrachiopalmar splint in neutral position. The stitches were removed at 10 days,
the plaster splint was removed at 21 days, and the Kirschner wire and the button were
removed topically at 6 weeks, and passive mobilization of the fingers and then physical
therapy at 8 weeks were indicated. Control was performed at 12 weeks, with the patient
presenting a degree of total active mobility of 230, which corresponds to an excellent
functional result according to the formula of the American Society for Surgery of
the Hand (ASSH)[5] ([Fig. 5A and B]), which persisted until the end of the 9-month follow-up.
Fig. 2 The tendon graft after traversing below the remnant of the retinacular ligaments
until reaching the distal phalanx.
Fig. 3 Passage of the nylon through the epidural needle, previously linked to a button.
Fig. 4 (Black arrow) Distal end of the tendon after performing the tenodesis; it was shaped
like a fan and the edges were fixed to the conjoined lateral bands. (Black asterisk)
Recreation of the sagittal band made with the remaining tendon graft, to avoid dislocation
of the tendon in flexion.
Fig. 5 (A,B) At 12 weeks, an excellent functional result was already observed, which was maintained
up to 9 months of follow-up.
Discussion
In injuries to the extensor apparatus of the fingers, timely management is recommended
because these injuries hinder the person's daily routine. In addition, in a chronic
injury, an excellent functional result is hardly achieved due to the complexity, the
length of the tendon defect, and the retractions, adhesions, and joint stiffness that
are generally accompanied.[3]
[4] Little attention has been paid in the literature to the management of chronic injuries
of the extensor apparatus as opposed to chronic injuries of the flexor zone.[4] The reports found refer to the use of local tendon graft in defects measuring between
0.5 cm and 1 cm, depending on the area of injury, and the interposition of a tendon
graft in larger injuries, preferably a PL tendon graft.[3]
[6] In lesions of zones III to V, Lebailly and Chantelot[7] recommend the performance of a Foucher plasty using a hemitendon of the EDC, which
is rotated in the form of a hinge and is fixed at the level of the middle phalanx.
Adams[8] reported the reconstruction of the extensor apparatus in stages, first using silicone
implants until the formation of a fibrous tunnel. Then, in a second time, the space
was replaced with a tendon graft, and better results were obtained inserting the graft
at the level of the middle phalanx, because, in the distal phalanx, they had had cases
with delayed extension of the proximal interphalangeal (PIP) joint and decreased flexion
of the DIP joint, due to the fact that the contraction force of the EDC was directed
first to the DIP joint.[8]
In the case herein presented, in view of the large tendon defect and with the aim
of restoring the extensor mechanism, we proposed reconstruction with a long tendon
graft with a more tubular shape in order to obtain a greater moment of force. There
are different anatomical points for obtaining tendon grafts; however, the PL graft
on the same side of the lesion was preferred due to its proximity and ease. It is
important in the previous clinical examination to verify the existence of this tendon,
because it is absent in between 2.8% and 24% of the population.[9] In the case herein reported, the second surgical stage proposed by Adams[8] was imitated to avoid the delay of the PIP joint; after fixing the tendon in the
distal phalanx, it was flattened in the shape of a fan, resting on the area of the
triangular ligament in the middle phalanx, to form an adhesion, enabling PIP extension
and, by moment of force, extension of the MCP joint.[10] The edges were fixed to the conjoined lateral bands, to transmit tension to the
terminal tendon and achieve extension of the DIP and also to limit, in flexion, the
lateral displacement of the lateral extensor tendons. The DIP joint was stabilized
with a Kirschner wire to avoid possible deformities, such as hammer toe, and to reduce
the tension force at that level.
At the level of the metacarpal head, imitating the function of the sagittal bands,
which are bands that maintain the axis of the tendon when flexing,[2]
[10] this ligament was recreated by fixing it to the joint capsule, thus avoiding dislocation
of the tendon graft ([Fig. 4]).
With the above, we believe that the case could serve as an alternative example to
reproduce in more patients with chronic injuries of the extensor apparatus with a
large tendon defect and in whom the anatomy is often altered.
