Artery anatomy and tortuosity in the distal finger The arterial architecture in the finger distal to the proximal interphalangeal joint was studied in sixty-seven cadaver fingers with the aid of an operating microscope. The course, frequency, location, and diameter of the dorsal nail fold artery and its anastomosis was recorded. Similar measurements were performed for the palmar ana stomosis. The frequency of arterial tortuosity in the digital artery was compiled and a classification of its morphology devised. The characteristic of arterial tortuosity provides a degree of protection to these essential structures. Failure to recognize this facet of arterial anatomy may be one more factor contributing to our inability to successfully revascularlze the distal finger in certain patients. (J HAl"O SURG 1991; 16A:297·302.)
Dean O. Smith, DO, Chikayoshi aura, MD, Chihiro Kimura, MD, and Kiyotaka Toshimori, MD, Kiyotake, Miya zaki, Japan
Microsurgical repair of damaged structures is facilitated by a precise knowledge of the pertinent anatomy . This study was undertaken in hopes of defining the course of the major arteries in the distal finger. Materials and methods At the end of the gross anatomy course at the Miyazaki Medical College there are always several fingers left undissected. Sixty-seven digits were collected from the remains. There were 20 index, 19 long , 15 ring , and 13 small fingers studied; 36 fingers were from the right hand and 31 from the left. The sex of the specimens were not discernible after bodily dissection. All were of adult age and had died of natural causes . The digital arteries of each specimen were dissected with an operating microscope at x 10 power for the purpose of measuring the diameters of the palmar and dorsal arterial arches (Fig. I). Measurements were made with a Shinwa vernier calliper accurate to tenths
Fig. 1. The dorsal nail fold arch emerges from beneath the thickened lateral chord and courses over the junction of the proximal germinal nail matrix and extensor tendon insertion. The palmar arch is always much larger and distal to the volar arch.
From the Departments of Orthopedic Surgery and Anatomy, Miyazaki Medical College, Kiyotake, Miyazaki, Japan . Received for public ation Jan. 5, 1990; accepted in revised form March 22, 1990, No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint request s: Dean O. Smith , DO, Department of Orthopedic Surgery. Miyazaki Medical College. 5200 Kihara, Kiyotake, Miyazaki, Japan 889-16. 3/1121715
of a millimeter, A census was also taken of the tortuosity of these arteries . Morphologically two distinct types of tortuosity was apparent in these specimens. Results Palmar arch dissection. Dissection showed that 64 (95.5%) of 67 digits had an intact palmar arch. The overall average external diameter for this structure in THE JOURNAL OF HAND SURGERY
297
The Journal of
298
Smith et al,
HAND SURGERY
Fig. 2. A 270 degree tortuosity. Large arrow represents the area of the DIP joint line. The small arrow shows the origin of the distal dorsal artery. (Magnification x 8.)
Fig. 3. High-grade tortuosity. Arrol\' points to the origin of the dorsal arch. (Magnification x 8.)
digits 2 to 5 was 0.8 mm and ranged from an average of 0.7 mm in the long finger-to 0.9 mm in the ring finger (Table I). There are several ways to record the level at which this vascular anastomosis occurs and each can be helpful in accurately describing for the surgeon where this structure is to be found. The simplest is to measure the distance from the most distal point of the fingertip skin to the level of the most distal portion of
the arterial arch. These distances were: index, 13.8 mm; long, 13.9 mm; ring, 14.0 mm; and small, 12.7 mm. The overall average was a distance of 13.7 mm for the distance from the distal fingertip skin to the palmar arch. The classification of the fingertip from the distal interphalangeal (DIP) joint distally as formulated by Chaudakshetrin et aI. I provides helpful, easily recognized landmarks for orienting oneself. Zone 1 is the
Vol. 16A, No.2 March 1991
Artery anatomy and tortuosity ill distal finger
299
for these arteries was only significant for the long finger, t = , 1.837 (Table IV). Digital artery tortuosity. In the course of dissection, 66 (98.5%) of 67 digits were found to have a single dominant artery, the other having perfect symmetry between the ulnar and radial arteries. Tortuosity was graded in the following manner. Vessels that had a series of three curves of at least 90 degrees in succession were termed 270 degree turtuosity (Fig. 2). Vessels with tortuosity that was relatively linear, but tight and corkscrew form were counted as high grade tortuosity (Fig. 3).
Fig. 4. 'The distal palmararch lies at the base of the protuberantdistal phalangeal boss where it is maximally protected by the thickest amount of pulp. Note that the proper digital artery is tortuous. area from the joint line to the nail matrix; zone 2 is the germinal nail matrix distance; and zone 3 is the area distal to the nail matrix. No arches were recorded in zone 1. Zone 2 had 47 or 73.4%, and zone 3 had 17 for 26.6% (Table II). Dorsal nail fold arch. Just distal to the DIP joint there is invariably a dorsal branch artery of relatively large caliber that vascularizes the nail fold and extensor tendon insertion. This vessel consistently courses beneath a distinct condensation in the distal aspect of the lateral chord. The lateral chord is a fascia on each side of the finger that is usually a thin layer of connective tissue adherent to the overlying skin." As it passes distally past the nail matrix this broad flat structure coalesces into a chord. The dorsal nail fold artery emerges from beneath this structure in .close contact with the phalanx and loops dorsally directly over a crease created by the proximal aspect of the germinal nail matrix and the downward passing fibers of the extensor tendon . It continues on until it anastomoses with its companion vessel from the other side of the finger (Fig. I). Typically this arch is a tortuous little artery with multiple branches to the nail matrix and two larger proximal reflections near the midline overlying the area of tendon insertion . Sixty (89.6%) of 67 fingers had an intact dorsal nail fold artery anastomosis. The average diameter for this arch was 0.3 mm (Table III). At its origin from the digital artery the dorsal nail fold artery averaged 0.5 mm. The dominant digital artery tended to give origin to a larger dorsal artery although the difference in size
There were 68 of 132 vessels with 270 degree tortuosity for an overall frequency of 51.590. When this variable was compared with vessel dominance a highly significant correlation was found. The dominant vessel had this finding 68.2% of the time whereas 34.8% of nondominant conduits had 270 degree tortuosity, t = 3.82. This arterial architecture was noted to be in approximation with the DIP joint 62 times, the proximal interphalangeal (PIP) joint 12 times, and multifocal on 6 occas ions. High grade tortuosity was present in 22 (16.6 %) of 132 vessels. In dominant arteries, 19.7 % were affected in this way as were 13.6 % nondominant structures t = 0 .934, a difference with no statistical significance. High grade tortuosity was in the proximity of the DIP joint on 14 occasions, the PIP joint 8 times, and never multifocal. Discussion The data for the palmararterial arch is very similar to the survey performed on 45 digits by Chaudakshetrin et al.' who reported a 93% incidence of-arch formation in their injection study. They did not present an arch diameter as such, but one can be inferred from their data to be about 1.0 mm. In this new data there was an average diameter of 0.8 mm for the dominant vessel side of the arch and a 95.5% frequency of arch formation. That injection studies produce recognizable dilatation of vessels is well known. 3 When working with an amputated part , vessel diameters will most likely approximate the noninjected figures given in this report . What is important is where to look to find this structure. Edwards' suggested that the arch is "at about the epiphysial plate." This is not too useful since most replants are not done in children. Other investigators have measured from the fingertip proximally to find this artery or have related its position to dorsal structures such as the nail fold and plate. Usually there is some variability in these multiple specimen measurements as seen by the 12.7 mm small
The Journal of
300
HAND SURGERY
Smith et al.
Fig. 5. An extreme example of digital artery tortuosity. The vessel is coiled like a spring. The large arrow points to the DIP joint level and the small arrow to the origin of the dorsal arch. (Magnification X 8.)
Table I. Distal palmar arch diameters (mm) Digit
I
Index
I
Long
I
Number 19 18 Average Diameter 0.8 0.8 Overall average diameter, 0.82
Ring
Table III. Dorsal nail fold arch diameter (mm)
I--s,-na-/-/-
14
13
0.9
0.8
Digit
Index
Long
Number 17 17 Average Diameter 0.34 0.32 Overall arch diameter, 0.33
Ring
Small
14
12
0.34
0.30
Table II. Arch distance from finger tip (mm) Digit
I
Index
I
Long
Distance 13.8 13.9 Range 11-17 12-16 Overall average distance, 13.66
I
Ring
'--sm-a-/-/-
14.0 10-16
12.7 10-15
finger average and 14.0 mm ring finger number of Table II. The range for these digits was from 10 mm to
17 mm. The approximate arch position can be readily palpated taking into mind the anatomy of the fingertip. The pulp is a soft, tactile structure. It provides a pliant surface to aid in fine touch perception. It also acts like a cushion to protect the palmar arch. In grasp and percussion the force is transmitted not only to the pulp, but to the palmar boss of the distal phalanx as well. This bony prominence is similar to a bumper on a car and the pulp like a protective air bag for the digital artery (Fig. IV). The artery is always located at the
distal base of the slope in the most protected position. This is an easily palpated landmark even in an amputated member. The distal dorsal arch arising from the dorsal nail fold arteries is a highly consistent structure being present 89.6% of the time. It averages 0.3 mm in diameter. The dorsal nail fold arteries that give rise to this structure have an average diameter of 0.5 mm at their origin from the digital arteries. Although this artery has been previously studied, no diameters or frequency of appearance were given." This arch is always to be found overlying the groove on the dorsum of the finger where the base of the nail fold and plate matrix overlies the downward passing extensor tendon. This landmark can be appreciated when one pushes back and up on one's own fingernail. As the nail plate recesses, the skin of the nail wall wiggles ever so slightly in a straight line about 5 mm proximal to the eponychium. Immediately beneath lies the distal dorsal arch.
Vol. 16A, No.2 March 1991
Artery anatomy and tortuosity in distal finger
301
Table IV. Distal nail fold artery diameters (mm)
Digit
R*
I
Uf
Average Diameter 0.480 0.505 t = 0.720:1: Combined digit average diameter, 0.5\
R
I
0.563 1.83
Small
Rillg
Long
Index
U
R
0.495
0.546
I
U
R
0.560
0.485
I
U
0.477 0.\63
0.295
OR. Radial artery. tU. Ulnar artery. ft. Students t test of coefficiency for small sample sizes.
At the Shanghai Sixth People's Hospital more than 50 toe-to-hand transfers are performed each year, probably the most in the world. A free toe flap dissection will be abandoned if the feeding dorsal metatarsal artery drops below 0.3 mm in diameter. It is interesting to note that tile diameter of the dorsal arch averages 0.3 mm. Because of its limited territory it is unlikely that this arch could vascularize an entire replant. But it is a significant vascular conduit for the distal dorsal finger. Arterial tortuosity is something that has been apparent in the literature for at least 30 years if one closely studies pictures of angiograms from older often quoted reports." More recent arterial papers also clearly display this phenomenon':" but make no comment on it. Although our success in repairing arteries in amputations is relatively high it is not 100%, due to a combination of errors in technique and lack of pertinent information. Tortuosity is a very significant part of the arterial architecture being present in more than half of all arteries in the distal finger. It can be classified into two types. High grade tortuosity is a tight kinking of the vessel that gives the appearance of a corkscrew. This is a very rigid structure, the function of which is difficult to ascertain. It appears a bit more in the dominant artery, but this frequency is not statistically significant t = 0.934 (Table V). Tortuosity of 270 degrees is very common. It is present in both dominant and nondominant vessels, 68.2% versus 34.8%. This predilection for the larger artery is highly significant t = 3.82 or >99% confidence level (Table V). Although the numbers do not show it, having personally counted and graded the tortuosity it became evident that the degree with which this bending took place was usually more marked in the larger structure even when present bilaterally. Although a nondominant artery may have had at least three consecutive 90 degree deviations, the tightness to which this kinking occurred was usually greater on the larger side. It is readily apparent why this bending exists and
Table V. Arterial tortuosity High grade
Number of arteries surveyed AA with tortuosity In dominant arteries In nondominant arteries t value dominant versus nondominate AAs Location of tortuosity: Near DIP PIP Muitifocal
Q
tortuosity
270 tortuosity
132 22 13 9 0.934
132 68 45 23 3.82
14
9
o
62 12 6
why it has a tendency to occur in the dominant artery. The dominant vessel is more important in supplying nutrients to the finger and therefore if a protective mechanism was available it would make sense to find it where it is most vital. These bends act like an accordion opening and closing during flexion and extension of the joint. With the neurovascular bundle dissected open one can see this movement of the bends with flexion and extension of the joints. Linear tension on the artery is converted into gentle bending at the angles of the turns. Coiling or bending any structure gives it spring like elasticity: We are presently trying to measure the elasticity of the digital arteries in our laboratory. What can be protective in normal activities can result in increased tension at a repair site when an artery is shortened to freshen edges before anastomotic repair. Although a surgeon may only mobilize an artery a few millimeters to bring it into the working field, half of the time he will be straightening out a coil either more proximal or distal in the part of the neurovascular bundle that is not visible. For years arterial studies have been reported and each time the author will show an angiogram accompanied by a schematic. With few exceptions," the x-ray film shows tortuosity, yet the schematic has the arteries look-
302
Smith et al,
ing nice and straight. The digital artery in the distal finger is not usually straight: or even gently curved for that matter and all schematics should reflect this precise anatomy. Equations, such as the Hagen-Poiseuille formula, have made their way into the hand literature. 9 These work nicely for predicting laminar flow in hollow tubes. Why they would be accurate in the distal finger is unfathomable because they rely on factoring an assumed consistent radial diameter to the fourth power. An error in measuring the radius is therefore multiplied by 16 times! The digital artery is clearly not a hollow tube with a consistent diameter (Fig. 5). The location, course, caliber, and shape of the digital artery distal to the PIP joint is unique and must be appreciated in performing microvascular repair. REFERENCES .1. Chaudakshetrin P, Kumar VP, Satku K, Pho RWH. Digital artery diameters: an anatomic and clinical study. J HAND SURG 1987;6B:740-3.
The Journal of HAND SURGERY
2. McFarlane RM. Anatomy, Dupuytren's contracture. In: Green DP. Operative hand surgery. New York: Churchill Livingstone, 1988:556-7. 3. Bunce DFM. Atlas of arterial histology. St. Louis: Warren H. Green, 1974:1-269. 4. Edwards EA. Organization of the small arteries of the hand and digits. Am J Surg 1960;99:837-46. 5. Backhouse KM. The blood supply of the arm and hand. In: Tubiana R. The hand. Philadelphia: WB Saunders, 1984:304-8. 6. Warren RA, Kay NRM, Norris SH. The microvascular anatomy of the distal digital extensor tendon. J HAND SURG 1988;13B:161-3. 7. Yousif IN, Cunningham MW, Sanger JR, et al. The vascular supply to the proximal interphalangeal joint. J HAND SURG 1985;lOA:852-61. 8. Strauch B, Wilson DM. Arterial system of the fingers. J HAND SURG 1990;15A:148-54. 9. Leslie BM, Ruby LK, Madell SJ. Digital artery diameters: an anatomic and clinical study. J HAND SURG 1987; 12A:740-3.
Dean O. Smith, DO, Chikayoshi aura, MD, Chihiro Kimura, MD, and Kiyotaka Toshimori, MD, Kiyotake, Miya zaki, Japan
Microsurgical repair of damaged structures is facilitated by a precise knowledge of the pertinent anatomy . This study was undertaken in hopes of defining the course of the major arteries in the distal finger. Materials and methods At the end of the gross anatomy course at the Miyazaki Medical College there are always several fingers left undissected. Sixty-seven digits were collected from the remains. There were 20 index, 19 long , 15 ring , and 13 small fingers studied; 36 fingers were from the right hand and 31 from the left. The sex of the specimens were not discernible after bodily dissection. All were of adult age and had died of natural causes . The digital arteries of each specimen were dissected with an operating microscope at x 10 power for the purpose of measuring the diameters of the palmar and dorsal arterial arches (Fig. I). Measurements were made with a Shinwa vernier calliper accurate to tenths
Fig. 1. The dorsal nail fold arch emerges from beneath the thickened lateral chord and courses over the junction of the proximal germinal nail matrix and extensor tendon insertion. The palmar arch is always much larger and distal to the volar arch.
From the Departments of Orthopedic Surgery and Anatomy, Miyazaki Medical College, Kiyotake, Miyazaki, Japan . Received for public ation Jan. 5, 1990; accepted in revised form March 22, 1990, No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint request s: Dean O. Smith , DO, Department of Orthopedic Surgery. Miyazaki Medical College. 5200 Kihara, Kiyotake, Miyazaki, Japan 889-16. 3/1121715
of a millimeter, A census was also taken of the tortuosity of these arteries . Morphologically two distinct types of tortuosity was apparent in these specimens. Results Palmar arch dissection. Dissection showed that 64 (95.5%) of 67 digits had an intact palmar arch. The overall average external diameter for this structure in THE JOURNAL OF HAND SURGERY
297
The Journal of
298
Smith et al,
HAND SURGERY
Fig. 2. A 270 degree tortuosity. Large arrow represents the area of the DIP joint line. The small arrow shows the origin of the distal dorsal artery. (Magnification x 8.)
Fig. 3. High-grade tortuosity. Arrol\' points to the origin of the dorsal arch. (Magnification x 8.)
digits 2 to 5 was 0.8 mm and ranged from an average of 0.7 mm in the long finger-to 0.9 mm in the ring finger (Table I). There are several ways to record the level at which this vascular anastomosis occurs and each can be helpful in accurately describing for the surgeon where this structure is to be found. The simplest is to measure the distance from the most distal point of the fingertip skin to the level of the most distal portion of
the arterial arch. These distances were: index, 13.8 mm; long, 13.9 mm; ring, 14.0 mm; and small, 12.7 mm. The overall average was a distance of 13.7 mm for the distance from the distal fingertip skin to the palmar arch. The classification of the fingertip from the distal interphalangeal (DIP) joint distally as formulated by Chaudakshetrin et aI. I provides helpful, easily recognized landmarks for orienting oneself. Zone 1 is the
Vol. 16A, No.2 March 1991
Artery anatomy and tortuosity ill distal finger
299
for these arteries was only significant for the long finger, t = , 1.837 (Table IV). Digital artery tortuosity. In the course of dissection, 66 (98.5%) of 67 digits were found to have a single dominant artery, the other having perfect symmetry between the ulnar and radial arteries. Tortuosity was graded in the following manner. Vessels that had a series of three curves of at least 90 degrees in succession were termed 270 degree turtuosity (Fig. 2). Vessels with tortuosity that was relatively linear, but tight and corkscrew form were counted as high grade tortuosity (Fig. 3).
Fig. 4. 'The distal palmararch lies at the base of the protuberantdistal phalangeal boss where it is maximally protected by the thickest amount of pulp. Note that the proper digital artery is tortuous. area from the joint line to the nail matrix; zone 2 is the germinal nail matrix distance; and zone 3 is the area distal to the nail matrix. No arches were recorded in zone 1. Zone 2 had 47 or 73.4%, and zone 3 had 17 for 26.6% (Table II). Dorsal nail fold arch. Just distal to the DIP joint there is invariably a dorsal branch artery of relatively large caliber that vascularizes the nail fold and extensor tendon insertion. This vessel consistently courses beneath a distinct condensation in the distal aspect of the lateral chord. The lateral chord is a fascia on each side of the finger that is usually a thin layer of connective tissue adherent to the overlying skin." As it passes distally past the nail matrix this broad flat structure coalesces into a chord. The dorsal nail fold artery emerges from beneath this structure in .close contact with the phalanx and loops dorsally directly over a crease created by the proximal aspect of the germinal nail matrix and the downward passing fibers of the extensor tendon . It continues on until it anastomoses with its companion vessel from the other side of the finger (Fig. I). Typically this arch is a tortuous little artery with multiple branches to the nail matrix and two larger proximal reflections near the midline overlying the area of tendon insertion . Sixty (89.6%) of 67 fingers had an intact dorsal nail fold artery anastomosis. The average diameter for this arch was 0.3 mm (Table III). At its origin from the digital artery the dorsal nail fold artery averaged 0.5 mm. The dominant digital artery tended to give origin to a larger dorsal artery although the difference in size
There were 68 of 132 vessels with 270 degree tortuosity for an overall frequency of 51.590. When this variable was compared with vessel dominance a highly significant correlation was found. The dominant vessel had this finding 68.2% of the time whereas 34.8% of nondominant conduits had 270 degree tortuosity, t = 3.82. This arterial architecture was noted to be in approximation with the DIP joint 62 times, the proximal interphalangeal (PIP) joint 12 times, and multifocal on 6 occas ions. High grade tortuosity was present in 22 (16.6 %) of 132 vessels. In dominant arteries, 19.7 % were affected in this way as were 13.6 % nondominant structures t = 0 .934, a difference with no statistical significance. High grade tortuosity was in the proximity of the DIP joint on 14 occasions, the PIP joint 8 times, and never multifocal. Discussion The data for the palmararterial arch is very similar to the survey performed on 45 digits by Chaudakshetrin et al.' who reported a 93% incidence of-arch formation in their injection study. They did not present an arch diameter as such, but one can be inferred from their data to be about 1.0 mm. In this new data there was an average diameter of 0.8 mm for the dominant vessel side of the arch and a 95.5% frequency of arch formation. That injection studies produce recognizable dilatation of vessels is well known. 3 When working with an amputated part , vessel diameters will most likely approximate the noninjected figures given in this report . What is important is where to look to find this structure. Edwards' suggested that the arch is "at about the epiphysial plate." This is not too useful since most replants are not done in children. Other investigators have measured from the fingertip proximally to find this artery or have related its position to dorsal structures such as the nail fold and plate. Usually there is some variability in these multiple specimen measurements as seen by the 12.7 mm small
The Journal of
300
HAND SURGERY
Smith et al.
Fig. 5. An extreme example of digital artery tortuosity. The vessel is coiled like a spring. The large arrow points to the DIP joint level and the small arrow to the origin of the dorsal arch. (Magnification X 8.)
Table I. Distal palmar arch diameters (mm) Digit
I
Index
I
Long
I
Number 19 18 Average Diameter 0.8 0.8 Overall average diameter, 0.82
Ring
Table III. Dorsal nail fold arch diameter (mm)
I--s,-na-/-/-
14
13
0.9
0.8
Digit
Index
Long
Number 17 17 Average Diameter 0.34 0.32 Overall arch diameter, 0.33
Ring
Small
14
12
0.34
0.30
Table II. Arch distance from finger tip (mm) Digit
I
Index
I
Long
Distance 13.8 13.9 Range 11-17 12-16 Overall average distance, 13.66
I
Ring
'--sm-a-/-/-
14.0 10-16
12.7 10-15
finger average and 14.0 mm ring finger number of Table II. The range for these digits was from 10 mm to
17 mm. The approximate arch position can be readily palpated taking into mind the anatomy of the fingertip. The pulp is a soft, tactile structure. It provides a pliant surface to aid in fine touch perception. It also acts like a cushion to protect the palmar arch. In grasp and percussion the force is transmitted not only to the pulp, but to the palmar boss of the distal phalanx as well. This bony prominence is similar to a bumper on a car and the pulp like a protective air bag for the digital artery (Fig. IV). The artery is always located at the
distal base of the slope in the most protected position. This is an easily palpated landmark even in an amputated member. The distal dorsal arch arising from the dorsal nail fold arteries is a highly consistent structure being present 89.6% of the time. It averages 0.3 mm in diameter. The dorsal nail fold arteries that give rise to this structure have an average diameter of 0.5 mm at their origin from the digital arteries. Although this artery has been previously studied, no diameters or frequency of appearance were given." This arch is always to be found overlying the groove on the dorsum of the finger where the base of the nail fold and plate matrix overlies the downward passing extensor tendon. This landmark can be appreciated when one pushes back and up on one's own fingernail. As the nail plate recesses, the skin of the nail wall wiggles ever so slightly in a straight line about 5 mm proximal to the eponychium. Immediately beneath lies the distal dorsal arch.
Vol. 16A, No.2 March 1991
Artery anatomy and tortuosity in distal finger
301
Table IV. Distal nail fold artery diameters (mm)
Digit
R*
I
Uf
Average Diameter 0.480 0.505 t = 0.720:1: Combined digit average diameter, 0.5\
R
I
0.563 1.83
Small
Rillg
Long
Index
U
R
0.495
0.546
I
U
R
0.560
0.485
I
U
0.477 0.\63
0.295
OR. Radial artery. tU. Ulnar artery. ft. Students t test of coefficiency for small sample sizes.
At the Shanghai Sixth People's Hospital more than 50 toe-to-hand transfers are performed each year, probably the most in the world. A free toe flap dissection will be abandoned if the feeding dorsal metatarsal artery drops below 0.3 mm in diameter. It is interesting to note that tile diameter of the dorsal arch averages 0.3 mm. Because of its limited territory it is unlikely that this arch could vascularize an entire replant. But it is a significant vascular conduit for the distal dorsal finger. Arterial tortuosity is something that has been apparent in the literature for at least 30 years if one closely studies pictures of angiograms from older often quoted reports." More recent arterial papers also clearly display this phenomenon':" but make no comment on it. Although our success in repairing arteries in amputations is relatively high it is not 100%, due to a combination of errors in technique and lack of pertinent information. Tortuosity is a very significant part of the arterial architecture being present in more than half of all arteries in the distal finger. It can be classified into two types. High grade tortuosity is a tight kinking of the vessel that gives the appearance of a corkscrew. This is a very rigid structure, the function of which is difficult to ascertain. It appears a bit more in the dominant artery, but this frequency is not statistically significant t = 0.934 (Table V). Tortuosity of 270 degrees is very common. It is present in both dominant and nondominant vessels, 68.2% versus 34.8%. This predilection for the larger artery is highly significant t = 3.82 or >99% confidence level (Table V). Although the numbers do not show it, having personally counted and graded the tortuosity it became evident that the degree with which this bending took place was usually more marked in the larger structure even when present bilaterally. Although a nondominant artery may have had at least three consecutive 90 degree deviations, the tightness to which this kinking occurred was usually greater on the larger side. It is readily apparent why this bending exists and
Table V. Arterial tortuosity High grade
Number of arteries surveyed AA with tortuosity In dominant arteries In nondominant arteries t value dominant versus nondominate AAs Location of tortuosity: Near DIP PIP Muitifocal
Q
tortuosity
270 tortuosity
132 22 13 9 0.934
132 68 45 23 3.82
14
9
o
62 12 6
why it has a tendency to occur in the dominant artery. The dominant vessel is more important in supplying nutrients to the finger and therefore if a protective mechanism was available it would make sense to find it where it is most vital. These bends act like an accordion opening and closing during flexion and extension of the joint. With the neurovascular bundle dissected open one can see this movement of the bends with flexion and extension of the joints. Linear tension on the artery is converted into gentle bending at the angles of the turns. Coiling or bending any structure gives it spring like elasticity: We are presently trying to measure the elasticity of the digital arteries in our laboratory. What can be protective in normal activities can result in increased tension at a repair site when an artery is shortened to freshen edges before anastomotic repair. Although a surgeon may only mobilize an artery a few millimeters to bring it into the working field, half of the time he will be straightening out a coil either more proximal or distal in the part of the neurovascular bundle that is not visible. For years arterial studies have been reported and each time the author will show an angiogram accompanied by a schematic. With few exceptions," the x-ray film shows tortuosity, yet the schematic has the arteries look-
302
Smith et al,
ing nice and straight. The digital artery in the distal finger is not usually straight: or even gently curved for that matter and all schematics should reflect this precise anatomy. Equations, such as the Hagen-Poiseuille formula, have made their way into the hand literature. 9 These work nicely for predicting laminar flow in hollow tubes. Why they would be accurate in the distal finger is unfathomable because they rely on factoring an assumed consistent radial diameter to the fourth power. An error in measuring the radius is therefore multiplied by 16 times! The digital artery is clearly not a hollow tube with a consistent diameter (Fig. 5). The location, course, caliber, and shape of the digital artery distal to the PIP joint is unique and must be appreciated in performing microvascular repair. REFERENCES .1. Chaudakshetrin P, Kumar VP, Satku K, Pho RWH. Digital artery diameters: an anatomic and clinical study. J HAND SURG 1987;6B:740-3.
The Journal of HAND SURGERY
2. McFarlane RM. Anatomy, Dupuytren's contracture. In: Green DP. Operative hand surgery. New York: Churchill Livingstone, 1988:556-7. 3. Bunce DFM. Atlas of arterial histology. St. Louis: Warren H. Green, 1974:1-269. 4. Edwards EA. Organization of the small arteries of the hand and digits. Am J Surg 1960;99:837-46. 5. Backhouse KM. The blood supply of the arm and hand. In: Tubiana R. The hand. Philadelphia: WB Saunders, 1984:304-8. 6. Warren RA, Kay NRM, Norris SH. The microvascular anatomy of the distal digital extensor tendon. J HAND SURG 1988;13B:161-3. 7. Yousif IN, Cunningham MW, Sanger JR, et al. The vascular supply to the proximal interphalangeal joint. J HAND SURG 1985;lOA:852-61. 8. Strauch B, Wilson DM. Arterial system of the fingers. J HAND SURG 1990;15A:148-54. 9. Leslie BM, Ruby LK, Madell SJ. Digital artery diameters: an anatomic and clinical study. J HAND SURG 1987; 12A:740-3.
