Keywords
vascularized tendon graft - vascularized palmaris tendon graft
Introduction
Presentation of delayed tendon injuries of hand is a common occurrence, necessitating
repair by tendon graft, usually autograft. While results of primary tendon surgery
are good,[1] functional results of delayed tendon graft depend lot on donor tendon, tendon bed,
and its vascularity.[2] Tendon graft healing has been studied extensively, be it animal models[3] or clinical experience.[4]
[5] Normally, tendon blood supply comes from “osteotendinous junction, musculotendinous
junction, and synovial sheath through meso-synovium.”[6] Tendons are hypovascular structures, yet mount “vascular donor response by increased
vascularity to trauma, attrition, or degeneration.”[7]
[8] Tendon grafts initially survive by imbibition of synovial fluid,[9] when covered by synovium, but if not having synovial layers, then by vascular flimsy
tissue invasion from surrounding tissues and also increased vascularity from two ends
of tendon graft anastomosis.[10] Depending upon the thickness of the tendon, while being vascularized, areas of necrosis
may occur which heal by fibrosis and adhesion to surrounding structures.[11] Finally, flimsy vascular connections between tendon bed and revascularized tendon
graft become fibrosed and hence are adhesions of repaired tendon, resulting in restricted
tendon mobility and ultimately less than satisfactory results of tendon surgery. Scarred
tendon bed, whether due to trauma, infection, or degeneration, results in thick adhesions
because of thicker vascular invasion from tendon bed.
To prevent excessive vascular invasion from surrounding tissue, the endovascularity
of the tendon is increased either by vascular tissue wrap in continuity to tendon
graft or by microvascular anastomosis to adjacent donor vessels. Such vascularized
tendon grafts have less vascular invasion from surrounding tissues, compared with
nonvascular tendon grafts, and better results.[12] Palmaris longus tendon is the most common tendon being used for tendon graft in
hand injuries.[13] It has multiple vascular pedicles arising from the ulnar artery. Palmaris longus
tendon graft is vascularized by anastomosis of its vascular pedicle to donor blood
vessels of the palm of hand as free vascularized tendon graft.
Technique
To familiarize with vascular pedicles of palmaris longus muscle, methylene blue was
injected in the brachial artery of a single fresh cadaveric arm and dissection of
the palmaris longus muscle and tendon with synovium was done. Three to four small
vessels were supplying muscle from the ulnar artery ([Fig. 1A]). One pedicle near the muscle origin and one near the musculotendinous junction
were considered of adequate size for vascular anastomosis ([Fig. 1B]).
Fig. 1 (A) Palmaris longus muscle tendon and two vascular pedicles in cadaveric dissection.
(B) Three vascular pedicles during surgery, magnified for better visualization.
Both flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons
in their fibrous sheath are exposed from the tip of the finger to the palm by Brunner's
incision (zigzag incision) and fibrous sheath, pulleys, synovial lining, condition,
and adhesion of residual tendons are noted. The tendon bed is prepared and the decision
to use a tip-to-palm tendon graft is confirmed. The synovial lining of the fibrous
sheath is checked again. All residual tendons, both FDP and FDS, are removed, preserving
more than 1.5 cm of the distal insertion of FDP and FDS tendon insertion, and excising
the rest of the chiasma as well. A feeding tube (size 6) is gently passed through
the fibrous sheath as a guide tube and to check the adequacy of the pulleys and determine
the length of the tendon graft needed from the tip of the finger to the palm. The
harvested tendon is then laid on the palm and the layout of the pedicle is determined.
The recipient artery and vein are identified ([Fig. 1B]), avoiding digital vessels, which may have been potentially compromised due to previous
injury or infections. Instead, muscular vessels to interossei muscles or skin perforators
are chosen for anastomosis.
Proximal tendon-to-tendon anastomosis is done using the Pulvertaft weave method, protecting
both donor and recipient vessels ([Fig. 2]). Before that, a dry run of the tendon in the fibrous sheath is performed. Once
the final position of the donor vessels is determined, the distal part of the tendon
is withdrawn into the palm. Vascular anastomosis is done with extra laxity of vessels
to ensure a relaxed lie ([Fig. 3]). After confirming patency for 15 minutes, the tendon is coaxed into the fibrous
space and brought out to the tip. Distal tendon anastomosis to the stump of the FDP
is completed. Tendon movement is rechecked to ensure the vascular anastomosis is not
impeded. Skin closure is performed and Plaster of Paris (POP) splintage done. A point
on the palm is chosen to check the patency of the anastomosis with a Doppler signal,
unimpeded by signals from other vessels, and for postoperative patency follow-up.
The skin is closed, and the final tension is rechecked. A POP slab is applied with
a window for Doppler checkup. Postoperative care includes passive flexion of fingers
for 1 week, followed by passive flexion and active extension for 3 weeks, then shifting
to active flexion and active extension for a further 6 weeks. Splintage is continued
for 3 months postexercise, with no weight bearing for 6 months.
Fig. 2 (A) Palmaris longus muscle tendon along with tenosynovium, dissected out with vascular
pedicles in continuity, being perfused by its own pedicle ensuring perfusion before
being disconnected for transfer to hand. (B) Tendon along with sleeve of muscle transferred to hand.
Fig. 3 (A) End-to-end arterial anastomosis for artery and for vein for case no 1 and (B) same for case no 2. Also, note some blood oozing after successful arterial and venous
anastomosis.
Case No 1
A 23-year-old male sustained sharp cut in the 5th finger of the right hand which was
operated elsewhere ([Fig. 4A]), presented to us after few months. On presentation, zone II injury with some stiffness
in the distal interphalangeal (DIP) joint was noticed. Initially, the 5th finger was
explored by zigzag incision and tip-to-palm graft planned. Pulleys in fibrous sheath
were examined and retained. Dense adhesions of the ruptured tendon were present in
the fibrous sheath. Decision to use vascularized tendon palmaris longus muscle was
made and tendons were harvested along with its paratenon. Vascular supply to the palmaris
longus muscle was explored and dissected out. Matching size of recipient perforator
and its length was dissected in the palm of the hand sparing the digital vessels.
The size of the artery usually is less than 1 mm. In the palm, anastomosis is done
end-to-end both for arteries and veins. For postoperative monitoring of anastomotic
patency, point on the hand for Doppler study was marked. After 3 weeks, we did color
Doppler which confirmed the patent vessel. Tendon repair had good strength and glide
after 6 months of surgery. [Videos 1] and [2] show that the stiffness of the DIP joint persisted.
Fig. 4 (A) Case no 1 having failed primary surgery for tendon injury and (B) case no 2 with site of injury and had treated suppurative tenosynovitis.
Video 1 Good flexion of vascularized tendon grafted finger. Distal interphalangeal (DIP)
joint persisting. Preop stiffness of DIP joint persisting.
Video 2 Good power in finger against resistance applied.
Case No 2
A 35-year-old male with FDP/FDS injury at the 4th finger ([Fig. 4B]), which had got infected. We operated after 3 months of subsidence of infection.
On exploration, the fibrous sheath and synovial sheath had collapsed and scarred,
without smoothness and softness. Residual tendons were scarred, gray, and adherent
to the fibrous sheath. Residual tendons were excised. Pulleys were found to be adequate
after gentle dilatation by metal dilators, and had absence of synovial lining. Harvested
palmaris longus muscle tendon had vessels of finer size, and end-to-end anastomosis
for arteries and veins was done successfully. Acoustic Doppler in immediate postoperative
period and color Doppler after 3 months suggested patency of anastomosis. Functional
recovery was good ([Fig. 5]) with no stiffness of interphalangeal joints after 6 months postop ([Video 3]).
Fig. 5 (A) Final result after follow-up of 6-month period with full flexion and (B) extension in finger with vascularized tendon graft.
Video 3 Good flexion and extension in vascularized tendon graft finger after follow-up of
6 months.
Discussion
Despite good results of primary tendon repair in tendon injuries, need for tendon
grafts for delayed presentation of hand injuries are common. Combined results of tendon
injury as analyzed by Buck–Gramcko score was 32% very good, 26.4% good, 15.1% satisfactory,
and 26.5% poor.[14] To improve upon these results, research in animal experiments demonstrated significant
improvement in decreasing adhesions and ultimate functional improvement by vascularizing
the tendon graft by either having deep fascia in continuity to tendon[15] or using vascularized tendon based on perfusion artery as flap. Vermeylen and Monballiu
in 1991 presented vascularized extensor indicis proprius (EIP) tendon graft based
on the second metacarpal artery for flexor tendon graft[16] or tendon being vascularized on available vascular artery as proposed by Morrison
and Cleland.[17] Tendon graft adhesion is the main cause of poor results. Vascularization of graft
tendon is to increase its endovascularity and to make it less dependent on flimsy
vascular invasion which ultimately leads to dense tendon adhesion. This procedure
also supplements/replaces initial phase of nutrition by synovial imbibition, simultaneously
transferring gliding surface of tenosynovium. Vascular channels in synovial sheath
run in a longitudinal axis from which multiple anastomosing vessels are branched,
producing synovial fluid for nourishing tendons and producing frictionless bed at
the same time. Vessels of tendon and synovial sheath of graft get anastomosed to osteotendinous
and proximal tendon stump to complete the vascular arcade.
Multiple authors have presented advantages of vascularized tendon graft in improving
functional results both in scarred tendon beds or when using extrasynovial tendon
as donor graft. Moriyama[15] in 1992 presented a comparative study in 40 rabbit's legs, where gliding tendon
beds were destroyed by liquid nitrogen, and randomly vascularized and nonvascularized
tendon grafts transferred. Histologically vascularized tendons fared better with less
adhesions to surrounding tissues. Singer et al[18] used primates where seven vascularized extensor hallucis longus tendon grafts were
compared with eight nonvascularized tendon grafts placed in fibro-osseous canals.
After 5 months, those with vascularized tendon grafts had patent vascular pedicles
and fared better in terms of simulated total active motion of toes and rupture rate.
In clinical series, Cavadas et al[19] in 2006 reported a single case of tendon reconstruction of ring finger using FDS
of the same finger as free vascularized tendon from branch arising from the ulnar
artery and anastomoses to the palmar arch. Ulnar artery was reanastomosed. Functional
result reported was good. Cavadas et al[20] again in 2015 presented a review of 38 patients with 40 flexor tendon reconstructions
where 37 pedicled flaps were used and 3 free flaps were used. While for single-stage
flexor tendon repair, vascularized tendon graft did better but to find a place in
reconstructive armamentarium, more is needed to be done, and Cavadas in 2023 reported
five cases of flexor pollicis longus (FPL) tendon repair on the branch of ulnar artery
showing refinement in microsurgery where the ulnar artery did not need to be injured
or resected or reconstructed.[20] Durand et al[12] and Vermeylen and Monballiu proposed graphics for vascularized EIP tendon graft
based on the branch of metacarpal artery while using vascularized extensor tendon
for FPL reconstruction with good result ([Table 1]). Noteworthy is that in both animal studies and clinical studies have very few numbers
of cases suggesting this to be an evolving scenario but if we consider usage of vascular
tendons in cruciate ligament and Achilles ligaments, consensus is evolving that vascular
tendons give better results than nonvascular tendons.
Table 1
Clinical applications of vascularized tendon and outcome
|
Zheng et al[14]
|
2003
|
Vascularized plantaris tendon composite flap with skin and/or fascia in electric burns,
7 cases
|
Good outcome
|
|
Cavadas[20]
|
2015
|
Reconstruction of FPL tendon with vascularized tendon with ulnar artery preservation
|
Moderate outcome
|
|
Durand et al[12]
|
2021
|
Reconstruction of FPL and extensor tendon using pedicled extensor indicis propius
tendon, 2 cases
|
Good outcome
|
|
Leversedge[6]
|
2000
|
Reconstruction of FPL tendon with vascularized pedicled FDS tendon branch of ulnar
artery, 5 cases
|
Good outcome
|
Abbreviations: FDS, flexor digitorum superficialis; FPL, flexor pollicis longus.
We have successfully presented the feasibility of using vascularized palmaris longus
tendon without injuring the ulnar artery as vascularized tendon graft in two patients.
Both vascularized tendon grafts had patent anastomosis as confirmed by acoustic Doppler
and later by color Doppler, confirming that palmaris longus continued to have vascularity
from anastomosed vessels. Functionally, both patients had good outcome.
Conclusion
Vascularized tendon grafts are still in the preliminary stage and improved results
are being reported both in animal experiments and clinical situations. As the microsurgical
expertise improves, so shall difficult tendon, soft tissue bone injury repair employs
vascularized tendons as standalone or as part of skin and fascia replacement in hand
injuries.
