Keywords hand - fingers - cadaver - hand injury - reconstructive surgery
Introduction
Several authors have described variations in the caliber of the proper palmar and
dorsal arteries of each digit of the hand. Since multiple flaps described in reconstructive
hand surgery are based on the proper palmar digital arteries, such as the reverse-flow
ipsilateral flap and the heterodigital or Littler flap, an asymmetry in the caliber
of the palmar digital arteries would condition the choice of donor area and therefore
the result of the surgery. The aim of the present study is to perform a qualitative
comparison of the caliber of the proper palmar and dorsal digital arteries of the
ulnar and radial sides of each finger.
The first study on the arterial vascularization of the fingers was carried out by
Edwards in 1960,[1 ] based on arteriograms and a specimen prepared with nitrocellulose etching. Edwards
showed that not all palmar digital arteries have the same diameter, and that these
variations in size follow a fixed pattern in the thumb, index, and little fingers.
The predominant artery is located on the ulnar side of the thumb and index finger,
and on the radial side of the little finger. This predominant artery is larger in
caliber than the artery on the opposite side of the same finger. In contrast, the
arteries of the middle and ring fingers tend to have a more similar diameter and,
if not, they do not follow any specific pattern. Edwards believed that this arrangement
offered greater protection to the larger artery. The same author described transverse
palmar connections between the palmar digital arteries of each finger, known as transverse
digital arches, with consistent origins relative to the pulleys of the flexor tendons.
Later, Leslie et al.[2 ] compared the diameter of the digital arteries on the ulnar and radial sides of each
finger at the level of the diaphysis of the proximal phalanx. The authors[2 ] concluded that, in general, the predominant artery is located on the ulnar side
in the index and middle fingers, and on the radial side in the ring and little fingers.
In 1990, Strauch and De Moura[3 ] carried out an anatomical study of the arterial system of the fingers by dissecting
141 fingers from non-cryopreserved cadavers. These authors[3 ] concluded that, in the thumb, index and middle finger, the proper palmar digital
artery on the ulnar side tends to have a larger caliber. In the ring finger and little
finger, the predominant artery would be on the radial side. Consequently, they recommended
prioritizing the reconstruction of the artery on the ulnar side in case of trauma
to the first three fingers, the opposite being true for the ring and little fingers.
Recently, a study by Coderech Carretero et al.[4 ] on the caliber and flow dominance of the arteries of the hand and fingers using
Doppler ultrasound has shown results similar to those previously discussed. Thus,
in the first three fingers of the hand, the proper palmar digital artery on the ulnar
side had a larger caliber. In contrast, the predominant artery in the ring and little
fingers was located on the radial side.[4 ]
Other authors have focused their studies on the vascularization of the thumb, such
as Earley,[5 ] who in 1986 showed that in 90% of the cases the proper palmar digital artery on
the ulnar side of the thumb (mean diameter: 1.8 mm) has a larger caliber than that
of the artery on the radial side (mean diameter: 1.1mm), thus being between 25% and
30% larger.
The transverse digital palmar arches, originally described by Edwards[1 ] in 1960, provide transverse communication to the proper palmar digital arteries
of both sides of each finger. These branches, with consistent origins relative to
the pulleys of the flexor tendons, are the proximal transverse digital, middle transverse
digital, and distal transverse digital arteries ([fig. 1 ]). In the thumb, we find the proximal digital transverse arch at the neck of the
phalanx, and the distal transverse arch, at the level of the fingertip.[1 ]
[3 ]
Fig. 1 Transverse digital palmar arches of Edwards[1 ] and dorsal branches of the proper palmar digital arteries. Palmar view (A ) and lateral view (B )
As for the arterial vascularization of the dorsal aspect of the fingers, it depends
on the proper palmar digital arteries and the proper dorsal digital arteries.
The proper palmar digital arteries give off three dorsal branches on each side of
each phalanx. These branches, which have a regular distribution, are: the condylar
artery, the metaphyseal artery, and the dorsal cutaneous artery ([fig.1 ]).[3 ]
The proper dorsal digital arteries also contribute to the arterial supply of the dorsal
aspect of the fingers. Edwards[1 ] considered the proper dorsal digital arteries to be insignificant branches of the
dorsal metacarpal arteries, with the exception of those of the thumb. And even in
cases in which the proper dorsal digital arteries were more developed, they tended
to disappear at the level of the proximal phalanx.
The results of the study carried out by Earley,[5 ] focused on the vasculature of the thumb, indicate that its proper dorsal digital
arteries are extremely variable and small, even absent when the dorsal branches of
the first palmar metacarpal artery are large. Parks et al.[6 ] agree with the fact that the dorsal arteries of the thumb have a small caliber,
and conclude that they can have variable origins: the deep radial artery, the arteries
of the first commissure, and/or the main artery of the thumb.
Materials and methods
Six cryopreserved arms, amputated proximally to the elbow joint, were arterially injected
with latex. The injection principles proposed by Rees and Taylor[7 ] were followed.
Thus, the brachial artery was cannulated with a catheter and transverse incisions
were made on the distal phalanges of all the fingers. Latex was then injected through
the brachial artery by pulsatile manual pressure with a 60-mL syringe. The exit of
the latex through the transverse incisions of the fingers enabled the verification
that the injection was correctly performed.
Amputations were performed at the level of the metacarpophalangeal or wrist joints.
In one of the specimens, several axial sections were made in each of the fingers of
the hand.
Subsequently, the pieces were prepared using the tissue-clearing technique by Spalteholz,[8 ] as well as a modified version of the above-mentioned technique with glycerin, with
the aim of showing the vascularization of the fingers without the artifacts pertaining
to dissection.
In the case of the conventional Spalteholz[8 ] tissue-clearing technique, some of the pieces injected with black latex were progressively
dehydrated by immersing them in 60% ethanol for a week and then changing them every
week to concentrations 10% higher until reaching a concentration of 100%. Subsequently,
the pieces were immersed twice for a week in a concentration of 100% ethanol and finally
in toluene for 2 successive periods of 1 week. Finally, the pieces were placed in
a mixture of three parts of methyl salicylate and two parts of benzyl benzoate. The
specimens were photographed while immersed in the liquid, fully transparent.
In the case of the Spalteholz[8 ] technique modified with glycerin, the pieces injected with black or red latex were
immersed in a mixture of 50% water and 50% glycerin for 1 day. Subsequently, at successive
24-hour intervals, the liquids were replaced by glycerin concentrations of 75%, 85%,
and, finally, by pure glycerin. The transparent pieces were photographed submerged
in pure glycerin.
Results
The results of the present study, which are summarized in [Table 1 ], show that, in most cases, the diameter of both palmar digital arteries of each
finger is different. This gauge difference follows a definite pattern in the index,
middle finger, and little finger.
Table 1
Case 1
Case 2
Case 3
Case 4
Case 5
Case 6
Proper palmar digital arteries (predominance)
Thumb
Radial
Ulnar
Ulnar
Radial
No differences
(Thumb amputation)
Index finger
Ulnar
Ulnar
Ulnar
Ulnar
Ulnar
Ulnar
Middle finger
Ulnar
Ulnar
Ulnar
Ulnar
No differences
Ulnar
Ring finger
Ulnar
Radial
Radial
No differences
No differences
Radial
Little finger
Radial
Radial
Ulnar
Radial
Radial
Radial
Proper dorsal digital arteries (predominance)
Ulnar of the thumb (or ulnar side of the thumb)
Both arteries of the thumb and the radial artery of the index
Ulnar of the thumb (or ulnar side of the thumb)
Ulnar of the thumb (or ulnar side of the thumb)
Both arteries of the thumb
Ulnar of the thumb (or ulnar side of the thumb)
Hand laterality/technique used
Right hand/glycerin
Right hand/glycerin
Right hand/glycerin (4th-5th fingers) and conventional Spalteholz (1st-3rd fingers)
Left hand/Spalteholz
Right hand/Spalteholz
Right hand/glycerin
In all the specimens, the predominant artery of the index finger is located on the
ulnar side ([fig. 2 ]). Similarly, in five of the six cases, the palmar digital artery of the middle finger
is larger on the ulnar side; in the remaining case, there is no difference between
both arteries. Regarding the little finger, the artery on the radial side has a larger
diameter in five of the six specimens; only in one case the predominant digital artery
is located on the ulnar side ([fig. 3 ]).
Fig. 2 Ulnar (A ) and radial (B ) borders of the index finger of the left hand; preparation with conventional Spalteholz[8 ] technique. The proper palmar digital artery with the largest caliber is consistently
located on the ulnar side of the index finger.
Fig. 3 Palmar (A ), radial (B ), and ulnar (C ) views of the little finger of the left hand; preparation with the conventional Spalteholz[8 ] technique. This is the only case in the present study in which the proper palmar
digital artery on the radial side (*) has a smaller diameter than that of the artery
on the ulnar side (**). Note that in the radial view, the artery on the radial side
has a very fine diameter that decreases until it almost disappears at the level of
the proximal phalanx. Through clearing, the artery on the ulnar side, with a much
larger caliber, can be seen.
In the thumb, one third of the specimens present a predominant palmar digital artery
on the ulnar side, one third, on the radial side, and, in the remaining third, no
significant differences between the two arteries are observed ([fig. 4 ]). When the palmar digital arteries of the ring finger show a different caliber,
they do not follow a certain pattern.
Fig. 4 Palmar (A ), ulnar (B ), and radial (C ) views of the thumb of the left hand; preparation with the conventional Spalteholz[8 ] technique. No significant differences in caliber were observed between both proper
palmar digital arteries (*). Note the proper dorsal digital artery on the ulnar side
(**).
As for the dorsal digital arteries, the only ones visible are the two of the thumb
and the one located on the radial side of the index finger. In the thumb, the dorsal
digital artery on the ulnar side has a larger diameter than that of the artery on
the radial side in all specimens. Comparatively, the diameter of the dorsal digital
artery on the ulnar side of the thumb is greater than that of the dorsal digital artery
on the radial side of the index finger.
We have also consistently observed the presence of the transverse digital palmar arches
and the dorsal branches of the palmar digital arteries ([fig. 5 ]).
Fig. 5 Radial view of the ring finger of the right hand; preparation with the Spalteholz[8 ] tchnique with glycerin. The presence of the dorsal branches of the proper palmar
digital arteries stands out (*).
Discussion
Anatomical study
Multiple studies[1 ]
[2 ]
[3 ]
[5 ] have documented differences in the caliber of the proper palmar digital arteries
of each finger. However, there are discrepancies about the specific pattern that each
finger follows.
All the authors who have included triphalangeal finger vascularization in their studies[1 ]
[2 ]
[3 ] observed that the pattern followed by the index and little fingers coincide: the
larger-caliber proper palmar digital artery is located on the ulnar side in the index
finger and on the radial side in the little finger. The results of the present study
are in accordance with these data since, in all the specimens examined, the proper
palmar digital artery on the ulnar side in the index finger is greater than that of
the radial side, and the proper palmar digital artery on the radial side in the little
finger predominates over the artery on the ulnar side. We have observed a single exception
to this described pattern, the case of a specimen that presented a predominant proper
palmar digital artery on the ulnar side of the little finger. This result reinforces
the importance of performing a modified Allen test prior to surgery, since the existence
of a dominant arterial pattern does not exclude the possibility of an anatomical variant.
In the case of the thumb, the results of studies[1 ]
[3 ]
[5 ] in the literature show a predominance of the proper palmar digital artery on the
ulnar side over the artery on the radial side. In the present study, however, we have
not observed this predominance. Our results in the thumb have been heterogeneous in
terms of the larger-caliber proper palmar digital artery: on the ulnar side in two
cases, radial in two cases, and without differences in another case. It is possible
that a study with a larger number of specimens points towards a predominance of the
ulnar side.
Regarding the middle and ring fingers, there is more discrepancy in the literature.
Edwards[1 ] concludes that there are differences between the proper palmar digital arteries
on both sides of the middle and ring fingers. Similarly, Leslie et al.[2 ] consider that the difference in caliber of these arteries is not statistically significant,
although they describe a predominance of the ulnar side in the middle finger, and
of the radial side in the ring finger. On the other hand, Strauch and De Moura[3 ] and Coderech Carretero et al.[4 ] locate the vascular axis of the hand in the third commissure, with an ulnar predominance
in the thumb, index finger, and middle finger, and a radial predominance in the ring
and little fingers. The results of the present study are in accordance with those
obtained by these authors[3 ]
[4 ] in the middle finger, with a larger-caliber proper palmar digital artery on the
ulnar side in all the specimens examined. On the other hand, the results in the ring
finger are disparate, although a certain predominance of the radial side could be
intuited: in three specimens, the artery on the radial side is larger; in one case,
the predominance is located on the ulnar side; and, in the remaining two cases, no
differences were observed between the two arteries. As in the case of the thumb, it
is possible that by increasing the number of specimens studied, the results coincide
with the pattern established by Strauch and De Moura[3 ] and Coderech Carretero et al.[4 ] to each finger.
Regarding the arterial vascularization of the dorsal aspect of the fingers, the results
of the present study are similar to those obtained in previous studies.[1 ]
[5 ]
[6 ] The proper dorsal digital arteries themselves are branches that either have very
small diameters or are absent, as Edwards concluded.[1 ] The exception to this rule would be the proper dorsal digital arteries of the thumb
and on the radial side of the index finger. In the present study, these are the only
visible proper dorsal digital arteries, especially those of the thumb. However, they
present variability in caliber and origin, as pointed out by previous studies.[1 ]
[5 ]
[6 ]
We have also almost consistently observed the presence of arterial connections between
both proper palmar digital arteries of each finger in the form of transverse digital
arches, described by Edwards[1 ] and later studied by Strauch and De Moura,[3 ] as well as the regular distribution of the dorsal branches of the proper palmar
digital arteries presented by these same authors.
Study limitations
It is not possible to carry out a quantitative comparative study of the diameter of
the digital arteries due to the limitations inherent to the anatomical technique used
to study it. Latex injection can distort, although minimally and homogeneously, the
diameter of the injected vessels. In addition, there is also a variation each time
the injection is performed, since there are several factors that are difficult to
control objectively, such as the pressure applied by the person when injecting. In
the Spalteholz[8 ] tissue-clearing technique, a certain degree of optical distortion can also occur
when the pieces are immersed in the mixture. Finally, as these are donors whose clinical
history is unknown, it is not possible to rule out the presence of factors that could
alter the vascular structure of the patient in life, such as peripheral arterial disease.
Conclusions
The proper palmar digital arteries on both sides present differences in their diameter
in the index, middle, and little fingers. Almost consistently, the ulnar-sided proper
palmar digital artery is larger than the artery on the radial side in the index and
middle fingers, and the artery on the radial side is larger than the artery on the
ulnar side in the little finger. However, anatomical variations make it necessary
to systematically perform a modified Allen test and Doppler ultrasound examination
of the patient before reconstructive surgery of the hand, since the difference in
caliber of both palmar digital arteries of each finger can condition the success of
the intervention.
The proper dorsal digital arteries with the largest diameter are those of the thumb
and the radial side of the index finger. The rest of the arterial vascularization
of the dorsal aspect of the fingers depends on the dorsal branches of the proper palmar
digital arteries, which are distributed regularly in each phalanx.
