Exploring New Frontiers of Microsurgery

This article presents the authors’ understanding and experience concerning anatomic studies and clinical methods in microsurgical hand reconstruction. The 4 parts of this article include anatomic study of the hand for developing new flaps; application of miniflaps from the hand, including clinical experience with 8 unique flaps in the hand; anatomic and clinical considerations concerning several flaps from other parts of the human body; And our experience with vascularized free toe joint transfer.

Key points

  • This article describe anatomic studies of the hand to develop new microvascular flaps, including the cutaneous branch network system of the lateral side of the finger, the anatomic relationship between the cutaneous branches of the proper digital artery and proper digital nerve, and the anatomy of perforator arteries in the thenar region.

  • The article presents our experience in clinical applications of 8 miniflaps for hand reconstruction.

  • The article describes findings and discusses the anatomy and clinical use of several flaps, including the dorsalis pedis flap, the medialis pedis vascular network flap, and the lateral pedis vascular network flap.

  • The article describes our experience of vascularized free toe joint transfer, and presents our method to improve the range of active motion following toe joint transplant.

Introduction

Over the past decades, the authors have sought to explore new frontiers in microsurgery to improve functional and aesthetic outcomes following microsurgical reconstruction of the hand. Our approach has been multidirectional toward this goal. This article outlines our efforts and describes how novel microsurgical ideas and procedures can be developed based on a more profound understanding of anatomy and functionality of the donor site tissue used in tissue transfer.

This article discusses 4 topics: (1) anatomic study of the hand for developing new flaps; (2) application of miniflaps from the hand, including clinical experience with 8 unique flaps in the hand; (3) anatomic and clinical discussion concerning several flaps from other parts of the human body; (4) our methods and outcomes in vascularized free toe joint transfer.

Introduction

Over the past decades, the authors have sought to explore new frontiers in microsurgery to improve functional and aesthetic outcomes following microsurgical reconstruction of the hand. Our approach has been multidirectional toward this goal. This article outlines our efforts and describes how novel microsurgical ideas and procedures can be developed based on a more profound understanding of anatomy and functionality of the donor site tissue used in tissue transfer.

This article discusses 4 topics: (1) anatomic study of the hand for developing new flaps; (2) application of miniflaps from the hand, including clinical experience with 8 unique flaps in the hand; (3) anatomic and clinical discussion concerning several flaps from other parts of the human body; (4) our methods and outcomes in vascularized free toe joint transfer.

Anatomy of the hand for developing new flaps

Choosing the hand region as a flap donor site for the repair of soft tissue hand defects can offer better function and appearance following reconstruction. However, these surgeries may damage major vessels of the hand during flap harvest. To address this concern, the investigators have explored the use of miniflaps from the hand and wrist regions to repair tissue defects in the hand since the year 2000. In exploring these miniflaps, our goals were to (1) limit the size of donor sites to allow direct closure; (2) carefully elevate flaps, preserving major vessels and nerves; and (3) better match the flap and recipient site’s skin color and texture.

Lateral Cutaneous Arterial Network of the Fingers

Several dorsal cutaneous branches arise from the proper digital artery at the proximal and middle phalanges. These dorsal cutaneous branches are 0.1 to 0.3 mm in diameter and form a vascular chain through which ample blood flows. The dorsal cutaneous branches travel from lateral to dorsal along the finger, arborizing into smaller secondary branches and then into ascending and descending branches. These branches connect to neighboring vessels to form a chain of cutaneous branches covering the lateral aspect of the finger ( Fig. 1 ). This network of cutaneous vessels allows the design of pedicle flaps without the need to sacrifice the digital artery in fingers when surgeons confirm abundant blood supply through the network.

Fig. 1
Numbers and location of dorsal cutaneous branches from the digital artery. ( A ) 1, dorsal cutaneous branches; 2, proper digital artery and nerve; 3, dorsal digital vein; 4, dorsal cutaneous branches. ( B ) In the same specimen shown in A , the dorsal cutaneous branches is highlighted with red ink showing continuity of the network along the entire length of the finger. Though in most fingers this network is large, the network is small in some fingers.
( Courtesy of Zeng Tao Wang, MD.)

Anatomic Relationship Between Cutaneous Branches of Digital Artery and Digital Nerve

The proper digital artery accompanies the proper digital nerve in the finger and lays deep to the proper digital nerve. The number of cutaneous branches running volar to the proper digital nerve is usually greater than those dorsal to the nerve ( Fig. 2 ). Very rarely, more cutaneous branches of the digital artery travel dorsal to the digital nerve rather than volar to it.

Fig. 2
The anatomic relationships between cutaneous branches of proper digital artery and proper digital nerve. ( A ) Numbers of cutaneous branches passing volar to the proper digital nerve exceed those along the deep aspect. ( B ) Cutaneous branches volar and dorsal to the digital nerve are equal in numbers; ( C ) rarely cutaneous branches dorsal to the digital nerve are more numerous than those volar to the digital nerve.
( Courtesy of Zeng Tao Wang, MD.)

When harvesting a miniflap, 1 side of the cutaneous branches is sacrificed in order to preserve the proper digital nerve. By carefully identifying all cutaneous branches from the proper digital artery, surgeons should ligate the side with fewer cutaneous branches during dissection to preserve a more robust blood supply to the flap ( Fig. 3 ).

Fig. 3
( A ) The side with fewer cutaneous branches from the digital artery is volar to the digital nerve. ( B ) The branches volar to the digital nerve were divided.
( Courtesy of Zeng Tao Wang, MD.)

Anatomy of Perforator Arteries in the Thenar Region

The perforator arteries in the thenar region originate from several distinct vascular sources. These perforator arteries can travel through 3 different muscular septa, creating longitudinal cutaneous branch network systems of the thenar soft tissue. One such septum exists between the radial side of the extensor pollicis brevis and the first metacarpal bone, where several cutaneous branches from the first dorsal metacarpal artery often exist ( Fig. 4 ). Another septum between the abductor pollicis brevis and flexor pollicis brevis contains 1 to 3 cutaneous branches that arise off the superficial branch of the radial artery and the princeps pollicis artery and their arterial connection ( Fig. 5 ). At the ulnar side of the superficial head of the flexor pollicis brevis, a rather large cutaneous branch originats off the superficial palmar arch, connecting to vessels of the radial proper digital artery of the index finger or from the princeps pollicis artery (see Fig. 5 ).

Fig. 4
The first dorsal radial metacarpal artery bifurcates from the radial artery in the anatomic snuff box running in this septum and giving off several cutaneous perforators.
( Courtesy of Zeng Tao Wang, MD.)

Fig. 5
Arterial supplies in the thenar area. a, radial artery; b, superficial palmar branch of the radial artery; c, superficial palmar arch; d, communicating branch between the superficial palmar arch and princeps pollicis artery; 1, cutaneous branches of the superficial palmar branch of the radial artery; 2, cutaneous branches from communicating branch between superficial palmar arch and princeps pollicis artery; 3, cutaneous branch perforating between abductor pollicis brevis and flexor pollicis brevis; 4, cutaneous branch of the superficial palmar arch.
( Courtesy of Zeng Tao Wang, MD.)

Miniflaps from the hand

Soft tissue deficits often result in traumatic finger injuries. The authors believe that the best reconstructive option for these soft tissue defects in the finger, especially the fingertip or pulp, is a regional or free flap from the hand or wrist. Various miniflaps harvested from the hand have been reported for smaller soft tissue defects of the hands. The pedicled homodigital flap remains a common option for fingertip defect. Omokawa and colleagues described the anatomy and clinical use of a hyothenar flap transfer for fingertip reconstruction. Kim and colleagues reported fingertip reconstruction using a hypothenar perforator flap. Kamei and colleagues published 2 cases of free thenar flaps pedicled on the superficial palmar branch of the radial artery for reconstruction of soft tissue defect in the hand. Omokawa and colleagues went on to describe the vascular and neural anatomy of the thenar region in further detail. Iwuagwu and colleagues introduced the use of free thenar flap based on the deep (main) branch of the superficial palmar branch of the radial artery. Zhu and colleagues used digital artery perforator flaps in fingertip reconstruction. This article presents our experience in using 8 types of miniflaps from the hand and wrist to repair defects in the fingers and thumb.

Digital Artery Cutaneous Branch Network Flap

A digital island flap pedicled on the proper digital artery is easy to harvest, but this procedure sacrifices a proper digital vascular bundle. In 2006, the authors designed a flap on the lateral side of the proximal phalanx based on the vascular network of dorsal cutaneous branches off the proper digital vessels ( Fig. 6 ). The axis of the flap lies along the midlateral line of the finger. To protect the vascular network on the lateral side of the finger, the authors include fascia with a width of 5 to 10 mm around the pedicle. Before flap harvest, the authors routinely test clamping major branches from the digital artery to the flap to ascertain that blood supply from neighboring branch network to the flap is sufficient. If the authors find the blood supply from the network is insufficient, the authors either abandon this type of the flap, or instead harvest the flap as a free flap based on a main branch that is clamped, or the authors harvest this flap based on the digital artery. The authors had to change the surgical plan in 20% of our patients. Preoperatively the authors could rule out 10% of fingers, which have no good network based on ultrasound or angiography. In other words, in 30% of the fingers, the arterial network flap cannot be harvested. The flap was transferred distally to cover soft tissue defects in the finger. The sensory nerve branch innervating the flap was coapted to the distal stump of the proper digital nerve.

Fig. 6
( A ) The flap is pedicled with a series of digital artery cutaneous branches: 1, proper digital artery; 2, cutaneous branches from proper digital artery; 3, digital artery cutaneous branches. ( B ) The flap is elevated and transferred distally.

Preoperative ultrasound or angiography can help rule out the fingers which have no reliable branch networks. However, plan changes based on intraoperative test clamping of the vessels to the flap are important. This flap could be harvested in about 70% of the fingers in our patients, in which blood supply through the network was reliable.

The authors applied this flap technique in 55 cases of finger pulp or nail bed loss associated with exposure of distal phalanx bone or the insertion site of the flexor digitorum profundus (FDP) tendon. This flap was introduced by the lead author (Wang ZT), and a coauthor (Zheng YM) performed most of the procedures presented here. Postoperative follow-up for these patients ranged from 6 to 12 months. Partial necrosis of the flap occurred in 2 cases (3.6%), and the wounds in these 2 cases healed with local debridement and regeneration with granulation tissue. All of the other patients recovered well from the procedure, with an acceptable appearance and texture of the flaps. Static 2-point discrimination on the flaps ranged from 8 to 12 mm at the time of follow-up. The donor site and clinical outcomes have proved to be identical to the digital artery island flap; however, both proper digital arteries of the finger are spared by using the digital artery cutaneous branch network instead of the proper digital artery for vascular supply.

This flap is illustrated in a 22-year-old man with a soft tissue and nail bed defect of the left index finger. A digital artery cutaneous branch network flap off the radial index finger was planned ( Fig. 7 A ). The flap, based on the vascular network of dorsal cutaneous branches off the proper digital artery, was raised and transferred to the cover nail bed defect ( Fig. 7 B, C). A follow-up at 6 months after surgery showed that the flap survived completely with a hypertrophic linear scar at the donor site ( Fig. 7 D, E).

Fig. 7
( A ) Flap design. ( B ) The flap raised without injury of proper digital artery and nerve (1, proper digital artery; 2, proper digital nerve; 3, digital artery cutaneous branch network; 4, tendon of extensor mechanism). ( C ) The flap was transferred distally to cover the recipient site, and donor site was closed directly. ( D ) Dorsal appearance of the fingers 6 months following surgery. ( E ) Volar appearance of the fingers 6 months after surgery.

Free Digital Artery Perforator Flap

The main disadvantage of a digital artery pedicle flap is the required sacrifice of 1 digital artery. This disadvantage can be overcome by using a flap based on the cutaneous branch network of the digital artery. The key to success in the cutaneous branch network flap is the meticulous identification of cutaneous branch connections. Both digital artery pedicle flaps and digital artery cutaneous branch network pedicle flaps leave a visible surgical scar between flap recipient site and donor site. A limitation of the 2 flaps is that they cannot be used to reconstruct soft tissue defects within the proximal phalangeal region.

Based on our anatomic studies, the diameter of the 2 major dorsal cutaneous branches of the proper digital artery is 0.1 mm to 0.3 mm at their origins where they bifurcate off the proper digital artery (see Fig. 1 ). A free flap based on cutaneous branch arteries and dorsal finger vein drainage can be designed with vascular anastomoses performed using 12-0 sutures ( Fig. 8 ). Since 2009, the authors have performed 30 cases using free digital artery cutaneous branch flap transfer. Most of the procedures were performed by coauthors (Zhu L and Hao LW) based on an idea from, and the first few procedures performed by, the lead author. The flap sizes ranged from 1.8 × 0.9 cm to 3 × 2 cm. All flaps survived well, without vascular complications. Prolonged mild flap edema was observed in 9 cases until up to 6 months following surgery. All edema eventually subsided in the flaps, restoring a better flap to recipient site match, which continued to improve as time progressed.

Fig. 8
The design of free digital artery perforator flap: 1, cutaneous branches originated from proper digital artery (pedicle); 2, proper digital artery and nerve; 3, dorsal digital vein; 4, branch of proper digital nerve.

This technique was shown in a 35-year-old man presenting with a fingertip defect in the right index finger. A digital artery perforator flap off the radial side of the middle finger was outlined ( Fig. 9 A ). Dissection of the flap began along the dorsal finger and progressed palmarly, exposing the digital artery as well as its perforators ( Fig. 9 B). The flap was raised and transferred to cover the soft tissue defect of the fingertip ( Fig. 9 C, D). The flap survived with a mild bulky appearance at 3 years follow-up.

Fig. 9
( A ) Flap was designed from the area of the proximal phalanx. ( B ) A cutaneous branch supplying the flap was identified. ( C ) The cutaneous branch was anastomosed to the proper digital artery. ( D ) Immediately after surgery.

Free Superficial Palmar Branch of the Radial Artery Flap

The superficial palmar branch of the radial artery gives off several cutaneous branches that supply the radial palmar skin before entering the abductor pollicis brevis muscle. These cutaneous branches have connections with other cutaneous branches in the thenar region, allowing larger flaps to be designed based on the superficial palmar branch of the radial artery (see Fig. 5 ). A free flap can be raised based on the superficial palmar branch of the radial artery ( Fig. 10 ), which can be anastomosed to the proper digital artery, or can be used to repair a digital artery defect as a flow-through flap. Depending on the specific needs, the flap can be designed with varying sizes, locations, and shapes. An example of this clinically advantageous flexibility in flap design is seen in soft tissue reconstruction of the finger. For defects on the dorsal finger, a flap can be raised proximal to the transverse wrist crease out of the glabrous palmar skin, providing a better skin match to the dorsal finger skin. In contrast, for defects of the volar glabrous skin, a flap can be raised distal to the transverse wrist crease. In addition, lateral finger defects can be reconstructed using a flap design centered on transverse wrist crease to include both skin types along with the natural transition.

Fig. 10
Design of several flaps in the thenar area (1, cutaneous branches from superficial palmar branch of the radial artery; 2, cutaneous branches emerge between the abductor pollicis brevis and flexor pollicis brevis; 3, cutaneous branches from the superficial palmar arch; 4, superficial palmar branch of the radial artery).

The surgical team led by a coauthor (Zhang YB) applied this flap technique in 33 cases from June 2003 to June 2015. Venous insufficiency of the transferred flap occurred in 1 case, which was salvaged with immediate exploration and revision of the vein anastomosis. Partial necrosis occurred in another case, which healed with local debridement and ingrowth of granulation tissue to the necrotic area. Thirty cases were followed and showed acceptable cosmetic outcomes.

This flap was illustrated in a 37-year-old man who had soft tissue loss over the lateral distal phalanx of the left thumb associated with exposure of distal phalanx. The authors designed a flap based on the superficial palmar branch perforators of the radial artery. The flap was harvested by first incising the proximal margin of the flap, taking care to identify and preserve the superficial venous drainage system. Next, the flap was elevated to identify the superficial palmar branch of the radial artery while preserving the cutaneous perforators. Afterwards, the free flap was harvested and transferred to the recipient site. The superficial palmar branch of the radial artery was anastomosed to a proper digital artery and the superficial vein was anastomosed to a dorsal thumb vein under an operating microscope. The flap provides good skin coverage to the defect site, which can be seen at 6 months after surgery ( Fig. 11 ).

Fig. 11
( A ) A soft tissue defect in the left thumb associated with bone exposure, and a superficial palmar branch of radial artery flap outlined at the proximal radial palm region. ( B ) The flap was raised. ( C ) The free flap was transferred to cover the soft tissue defect. The flap donor site was closed directly. ( D ) Good appearance of the flap coverage site and donor site 6 months after surgery.

Free Midthenar Flap

In the midthenar area, cutaneous vascular branches emerge between the abductor pollicis brevis and flexor pollicis brevis (see Fig. 5 ). The diameter of these cutaneous branches is larger than 0.2 mm, and superficial veins in this region are abundant. The authors have designed flaps that are supplied by a cutaneous artery and drained by superficial veins (see Fig. 10 ). The authors applied this approach in 9 cases from November 2007 to January 2015 with no flap losses.

One such case was a 27-year-old man who presented with a soft tissue defect over the ulnar aspect of the distal interphalangeal joint of the left small finger, with the FDP tendon and the distal phalanx exposed ( Fig. 12 A ). Cutaneous arterial branch locations in the muscle septum between the abductor pollicis brevis and flexor pollicis brevis were identified by Doppler examination preoperatively. The authors designed a thenar flap centered on these identified cutaneous arteries ( Fig. 12 B). Flaps were harvested by first incising along the ulnar margin of the flap, identifying 1 to 2 superficial veins and dissecting an appropriate length of these veins to serve as the flap drainage vessels. Through an incision in the proximal margin, the sensory nerve branches to the flap were also identified and divided with enough length. Second, dissection was continued deeper until the fascia of the superficial head of the flexor pollicis brevis was reached, then the flap was undermined radially in the prefascial plane over the flexor pollicis brevis muscle until reaching the septum between the abductor pollicis brevis and the flexor pollicis brevis muscles. Third, cutaneous branch perforators in the septum were carefully identified, then dissected free deeper for a longer pedicle and larger vessel diameter ( Fig. 12 C). Fourth, the cutaneous artery branch was ligated and the flap freed. Fifth, the flap was transferred to the recipient site and microvascular anastomoses performed between the cutaneous arterial branch of the flap to the digital artery and between the superficial veins of the flap to the superficial veins of the finger ( Fig. 12 D). The sensory nerve was coapted with the proximal stump of the ulnar proper digital nerve. The 2-year follow-up image shows complete survival of the transferred flap with a good cosmetic appearance. Static 2-point discrimination of the flap was 11 mm.

Nov 21, 2017 | Posted by in Dental Materials | Comments Off on Exploring New Frontiers of Microsurgery
Premium Wordpress Themes by UFO Themes