Publications by authors named "Mark W Ashton"

137 Publications

Increasing Perfusion Pressure Does Not Distend Perforators or Anastomoses but Reveals Arteriovenous Shuntings.

Plast Reconstr Surg Glob Open 2020 Jun 24;8(6):e2857. Epub 2020 Jun 24.

Taylor Lab, Department of Anatomy and Neurosciences, University of Melbourne, Victoria, Australia.

Background: It has been proposed that hyperperfusion of perforators and distension of anastomotic vessels may be a mechanism by which large perforator flaps are perfused. This study investigates whether increasing perfusion pressure of radiographic contrast in cadaveric studies altered the radiographic appearance of vessels, particularly by distending their anastomotic connections.

Methods: From 10 fresh cadavers, bilateral upper limbs above the elbow were removed. Three cadavers were excluded. Seven pairs of limbs were injected with lead oxide solutions via the brachial artery while distally monitoring intravascular pressure in the radial artery using a pressure transducer. One limb was injected slowly (0.5 mL/s) and the other rapidly (1.5 mL/s) to produce low and high perfusion pressures, respectively. Skin and subcutaneous tissue were then removed and radiographed.

Results: The filling of perforators and their larger caliber branches appeared unchanged between low- and high-pressure injections, with ( = 0.32) and ( = 0.94) ( = 0.10). However, high-pressure injections revealed arteriovenous shunting with filling of the tributaries of the major veins.

Conclusions: This study demonstrated that increased perfusion pressure of the cutaneous arteries (1) did not change the caliber of vessels; (2) did not convert choke to true anastomoses; and (3) revealed arteriovenous shunting between major vessels with retrograde filling of venous tributaries as pressure increased. This suggests that it is not possible to distend anastomotic connections between vascular territories by increasing perfusion alone.
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http://dx.doi.org/10.1097/GOX.0000000000002857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339302PMC
June 2020

The Functional Anatomy of the Ophthalmic Angiosome and Its Implications in Blindness as a Complication of Cosmetic Facial Filler Procedures.

Plast Reconstr Surg 2020 10;146(4):745

From the Taylor Lab, Department of Anatomy and Neuroscience, and the Department of Surgery, University of Melbourne; the Plastic and Reconstructive Surgery Unit, The Royal Melbourne Hospital; and the Professorial Plastic Surgery Unit, Epworth Freemasons Hospital.

Background: Blindness following facial filler procedures, although rare, is devastating, usually acute, permanent, and attributed to an ophthalmic artery embolus. However, blindness may be delayed for up to 2 weeks, sometimes following injection at remote sites, suggesting alternative pathways and pathogenesis.

Methods: Seeking solutions, fresh cadaver radiographic lead oxide injection, dissection, and histologic studies of the orbital and facial pathways of the ophthalmic angiosome, performed by the ophthalmic artery and vein, both isolated and together, and facial artery perfusions, were combined with total body archival arterial and venous investigations.

Results: These revealed (1) arteriovenous connections between the ophthalmic artery and vein in the orbit and between vessels in the inner canthus, allowing passage of large globules of lead oxide; (2) the glabella, inner canthi, and nasal dorsum are the most vulnerable injection sites because ophthalmic artery branches are anchored to the orbital rim as they exit, a plexus of large-caliber avalvular veins drain into the orbits, and arteriovenous connections are present; (3) choke anastomoses between posterior and anterior ciliary vessels supplying the choroid and eye muscles may react with spasm to confine territories impacted with ophthalmic artery embolus; (4) true anastomoses exist between ophthalmic and ipsilateral or contralateral facial arteries, without reduction in caliber, permitting unobstructed embolus from remote sites; and (5) ophthalmic and facial veins are avalvular, allowing reverse flow.

Conclusion: The authors' study has shown potential arterial and venous pathways for filler embolus to cause blindness or visual field defects, and is supported clinically by a review of the case literature of blindness following facial filler injection.
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http://dx.doi.org/10.1097/PRS.0000000000007155DOI Listing
October 2020

The quadriceps Femoris allograft as an extension of the Angiosome concept: A cadaveric-based anatomical feasibility study.

Microsurgery 2020 Feb 21;40(2):189-199. Epub 2019 Jun 21.

The Taylor Lab, Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia.

Background: Vascularised composite allo-transplantation (VCA) is emerging as a tailored approach for complex tissue reconstruction. This study focuses on the quadriceps VCA as a potential solution for tissue repair, following trauma, necrotising fasciitis/myositis, or tumor ablation.

Methods: Dissections were undertaken in 10 adult cadaveric lower limbs to characterize the blood supply to the quadriceps femoris for en bloc muscle allo-transplantation. A mock cadaveric transplantation was performed to (a) define the best neurovascular VCA design and (b) test the feasibility of the procedure. A review of 54 archival radiograph studies from the institution was also performed to further evaluate the muscle vasculature.

Results: In two lower limbs, the quadriceps VCA was harvested designed on the common and superficial femoral vessels and nerve, which revealed a lengthy and bloody dissection, especially of the veins, which could increase clinically with the inability to use a tourniquet for most of the dissection. However, review of our previous archival studies showed that all four quadriceps muscles are supplied within the lateral circumflex femoral angiosome. In a further eight lower limbs, the quadriceps femoris muscle group consistently received its blood supply from the lateral circumflex femoral angiosome, verified by selective lead oxide injections of this artery. The vastus medialis appeared to have a more tenous blood supply distally based on this angiosome. A successful mock cadaveric transplant was performed based on this data.

Conclusions: We suggest that the best neuromuscular quadriceps VCA should be (a) designed on the lateral circumflex femoral pedicle, (b) should be raised from distal to proximal, and (c) should include the descending genicular vessels as a potential supplemental supply to vastus medialis, should all four muscles be required.
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http://dx.doi.org/10.1002/micr.30479DOI Listing
February 2020

The Role of Anastomotic Vessels in Controlling Tissue Viability and Defining Tissue Necrosis with Special Reference to Complications following Injection of Hyaluronic Acid Fillers.

Plast Reconstr Surg 2018 06;141(6):818e-830e

Parkville, Victoria, Australia.

Background: Most target areas for facial volumization procedures relate to the anatomical location of the facial or ophthalmic artery. Occasionally, inadvertent injection of hyaluronic acid filler into the arterial circulation occurs and, unrecognized, is irreparably associated with disastrous vascular complications. Of note, the site of complications, irrespective of the injection site, is similar, and falls into only five areas of the face, all within the functional angiosome of the facial or ophthalmic artery.

Methods: Retrospective and prospective studies were performed to assess the site and behavior of anastomotic vessels connecting the angiosomes of the face and their possible involvement in the pathogenesis of tissue necrosis. In vivo studies of pig and rabbit, and archival human total body and prospective selective lead oxide injections of the head and neck, were analyzed. Results were compared with documented patterns of necrosis following inadvertent hyaluronic acid intraarterial or intravenous injection.

Results: Studies showed that the location of true and choke anastomoses connecting the facial artery with neighboring angiosomes predicted the tissue at risk of necrosis following inadvertent intraarterial hyaluronic acid injection.

Conclusion: Complications related to hyaluronic acid injections are intimately associated with (1) the anatomical distribution of true and choke anastomoses connecting the facial artery to neighboring ophthalmic and maxillary angiosomes where choke vessels define the boundary of necrosis of an involved artery but true anastomoses allow free passage to a remote site; or possibly (2) retrograde perfusion of hyaluronic acid into avalvular facial veins, especially in the periorbital region, and thereby the ophthalmic vein, cavernous sinus, and brain.
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http://dx.doi.org/10.1097/PRS.0000000000004287DOI Listing
June 2018

The Functional Angiosome: Clinical Implications of the Anatomical Concept.

Plast Reconstr Surg 2017 Oct;140(4):721-733

Parkville, Victoria, Australia.

Background: The angiosome is a three-dimensional block of tissue supplied by a source vessel with its boundary outlined either by an anastomotic perimeter of reduced-caliber choke vessels or by true anastomoses with no reduction of vessel caliber. This article focuses on the role of these anastomotic vessels in defining flap survival or the necrotic pattern seen in fulminating meningococcal septicemia.

Methods: Experiments in pigs, dogs, guinea pigs, and rabbits over the past 46 years were reviewed, focusing on the necrosis line of flaps, the effects of various toxins in vivo, and correlating these results in the clinical setting.

Results: Experimentally, choke anastomoses are functional and control flow between perforator angiosomes. They (1) permit capture of an adjacent angiosome when the flap is raised on a cutaneous perforator in 100 percent of cases, with the necrosis line occurring usually in the next interperforator connection; (2) confine flow to the territory of the involved artery when a toxin is introduced by spasm around its perimeter; and (3) lose this property of spasm when choke vessels are converted to true anastomoses following surgical delay, or where true anastomoses occur naturally, thereby allowing unimpeded blood flow and capture of additional angiosome territories. Clinical experience supports these observations.

Conclusions: The functional angiosome is the volume of tissue that clinically can be isolated on a source vessel. The area extends beyond its anatomical territory to capture an adjacent territory if connections are by choke anastomoses, or more if they are by true anastomoses.
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http://dx.doi.org/10.1097/PRS.0000000000003694DOI Listing
October 2017

Angiosome-Based Allografts: Vascularized Composite Allotransplantation for Tailored Subunit Reconstruction with Volkmann Ischemic Contracture as a Case in Point.

Plast Reconstr Surg 2017 Jun;139(6):1291e-1304e

Melbourne, Victoria, Australia.

Background: As we enter an age with new approaches to tissue reconstruction, the emphasis on the adage "like for like" has become even more relevant. This study illustrates the potential for several tailored vascularized composite allotransplantation reconstructive techniques and, in particular, for the management of Volkmann contracture.

Methods: Twenty fresh cadaver dissections and 30 archival lead oxide radiographic studies were examined to (1) identify potential upper limb vascularized composite allotransplantation donor sites (i.e., elbow, forearm, and flexor tendon complex) and (2) demonstrate a "mock transplant" of the vascularized volar forearm allograft for a severe Volkmann ischemia defect. They were designed without skin to reduce antigenicity.

Results: The elbow joint was supplied within the brachial angiosome and the flexor tendon complex of the flexor digitorum superficialis and flexor digitorum profundus by the superficial palmar arch of the ulnar angiosome. The forearm allograft of flexor muscles, median, ulnar, and anterior interosseous nerves, when harvested on the brachial vessels, was supplied within the radial, ulnar, and anterior interosseous angiosomes but could be based on the ulnar artery alone because of intramuscular connections with the other territories. A mock transplant was performed with a distal-to-proximal dissection of the allograft, facilitating the best and fastest technique.

Conclusions: This application of the angiosome concept highlights the anatomical feasibility of the volar forearm vascularized composite allotransplantation donor site focusing on a complex subunit problem in the upper limb-severe Volkmann ischemic contracture. It demonstrates the potential use and immunologic advantage of subdivided and modified nonskin variations of vascularized composite allotransplantation in reconstructive transplantation surgery.

Clinical Question/level Of Evidence: Therapeutic, V.
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http://dx.doi.org/10.1097/PRS.0000000000003360DOI Listing
June 2017

The Relationship of Superficial Cutaneous Nerves and Interperforator Connections in the Leg: A Cadaveric Anatomical Study.

Plast Reconstr Surg 2017 Apr;139(4):994e-1002e

Melbourne, Victoria, Australia.

Background: The lower limb is a source of many flaps both for closure of local defects and for free transfer. Fasciocutaneous flap techniques have been progressively refined, although the vascular basis for their success needs clarification.

Methods: Archival studies of 48 lower limbs were reviewed and combined with 20 studies of lower limbs from fresh cadavers, making a total of 68 investigations. Lower limbs were injected with a dilute lead oxide solution; the integument was removed and radiographed; and the cutaneous nerves were dissected, tagged with wire, radiographed again, and their paths traced on the original images.

Results: The major cutaneous nerves in the leg are paralleled by a longitudinal vascular axis often comprising long branches with large-caliber true anastomotic connections between perforators. The most highly developed vascular axes followed the medial sural cutaneous and saphenous nerves, together with their accompanying veins, immediately superficial to the deep fascia. The intervening areas were characterized by shorter branches usually connected by small-caliber choke anastomotic connections.

Conclusions: These findings provide the anatomical basis for the observed reliability of longitudinal flaps in the leg. The superficial cutaneous nerves of the leg, especially the saphenous and medial sural cutaneous nerves, are paralleled by a vascular axis on or beside the nerve comprising long perforator branches connected usually but not always by large-caliber true anastomotic connections. This emphasizes the importance of understanding the characteristics of interperforator anastomoses when designing and raising flaps.
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http://dx.doi.org/10.1097/PRS.0000000000003157DOI Listing
April 2017

The Lymphatic Anatomy of the Lower Eyelid and Conjunctiva and Correlation with Postoperative Chemosis and Edema.

Plast Reconstr Surg 2017 Mar;139(3):628e-637e

Melbourne, Toorak, and Fitzroy, Victoria, Australia.

Background: There are minimal data in the literature regarding the lymphatic drainage of the conjunctiva and lower eyelid and the relationship with postoperative chemosis and edema.

Methods: Injection, microdissection, and histologic and radiologic studies were conducted on 12 hemifacial fresh cadaver specimens. Indocyanine green lymphography was conducted in five volunteers.

Results: Histology identified lymphatic vessels superficial and deep to the orbicularis oculi. Cadaveric dissection, injection, and radiographic studies identified interconnecting superficial and deep facial lymphatic systems and a conjunctival lymphatic network draining through the tarsal plate to the deep lymphatic system. The superficial lymphatic collectors traveled in subcutaneous fat within the lateral orbital and nasolabial fat compartments. The lateral deep lymphatic collectors traveled beneath orbicularis oculi, then through the superficial orbicularis retaining ligament, and into the sub-orbicularis oculi fat in the roof of the prezygomatic space. These vessels descended to preperiosteal fat at the level of zygomaticocutaneous ligaments to travel adjacent to the facial nerve into preauricular nodes. Indocyanine green lymphography identified correlating draining pathways laterally to the parotid nodes and medially to submandibular nodes.

Conclusions: The authors have found that the lower eyelid and conjunctiva are drained by interconnecting superficial and deep lymphatic systems of the face. The superficial system is vulnerable to damage in incisions and dissection in the infraorbital area. The deep system is vulnerable to damage in dissection around the orbicularis retaining ligament and the zygomaticocutaneous ligaments. The authors suggest that concurrent damage to both the superficial and deep lymphatic systems, especially laterally, may be responsible for postoperative chemosis and edema.
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http://dx.doi.org/10.1097/PRS.0000000000003094DOI Listing
March 2017

Long-Term Patency of Lymphovenous Anastomoses: A Systematic Review.

Plast Reconstr Surg 2016 Aug;138(2):492-498

Parkville, Victoria, Australia.

Background: With advancements in technology and microsurgical techniques, lymphovenous anastomosis has become a popular reconstructive procedure in the treatment of chronic lymphedema. However, the long-term patency of these anastomoses is not clear in the literature.

Methods: A systematic review of the MEDLINE and EMBASE databases was performed to assess the reported long-term patency of lymphovenous anastomoses.

Results: A total of eight studies satisfied the inclusion criteria. Pooled data from four similar experiments in normal dogs showed an average long-term (≥5 months) patency of 52 percent. The only experiment in dogs with chronic lymphedema failed to show any long-term patency.

Conclusions: The creation of peripheral lymphovenous anastomoses with a moderate long-term patency rate has become technically possible. However, the long-term results in chronic lymphedema are limited.
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http://dx.doi.org/10.1097/PRS.0000000000002395DOI Listing
August 2016

The Evolution of Free Vascularized Bone Transfer: A 40-Year Experience.

Plast Reconstr Surg 2016 Apr;137(4):1292-1305

Melbourne, Victoria, Australia.

Background: The first successful free vascularized bone flap was performed on June 1, 1974 (and reported in 1975), using the fibula. This was followed by the iliac crest based on the superficial circumflex iliac artery in 1975 and then the deep circumflex iliac artery in 1978.

Methods: A total of 384 transfers using fibula (n = 198), iliac crest (n = 180), radius (n = 4), rib (n = 1), and metatarsal (n = 1) were used between June of 1974 and June of 2014 for reconstruction of the mandible (n = 267), maxilla (n = 20), clavicle (n = 1), humerus (n = 8), radius and ulna (n = 21), carpus (n = 3), pelvis (n = 2), femur (n = 11), tibia (n = 47), and foot bones (n = 4). Indications were tumor ablation (n = 286), trauma (n = 84), osteomyelitis (n = 2), and the congenital deformities hemifacial microsomia (n = 2) and pseudarthrosis of the tibia (n = 9) and ulna (n = 1).

Results: Successful transfer was achieved in 95 percent of patients. Union varied with the recipient bone, from 6 to 8 weeks in the jaw, 2 to 3 months in the upper limb, and 3 to 4 months in the femur and tibia. Union was fastest with iliac crest. The fibula provided easier dissection; it could be raised on either peroneal or anterior tibial vessels; the skin flap could be designed distally; it could be placed centrally in the medullary cavity of long bones; and hairline stress fracture in the lower limb frequently preceded rapid subperiosteal hypertrophy. The fibula lacks sufficient height for osseointegration, whereas iliac crest is ideal. Osteotomies of either bone are possible to straighten or increase curvature.

Conclusions: The fibula is best for long bone or angle-to-angle jaw reconstruction, especially in edentulous patients. Iliac crest is best for hemimandible, curved bones (pelvis, carpus, and metacarpus), and as an alternative for short, straight, 6- to 8-cm-long bone defects.
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http://dx.doi.org/10.1097/PRS.0000000000002040DOI Listing
April 2016

Vascularized Lymph Node Transfer: A Review of the Current Evidence.

Plast Reconstr Surg 2016 Mar;137(3):985-993

Parkville, Victoria, Australia From the Department of Anatomy and Neuroscience, University of Melbourne.

Over the past decade, lymph node transfer has rapidly gained popularity among plastic surgeons for the treatment of chronic lymphedema because of the initial promising results and its unique technical advantages compared with the other reconstructive options. However, its functional mechanism is still a matter of great debate, and some concerning reports have emerged regarding the safety of this procedure in patients with chronic lymphedema. The authors review the literature on the experimental and clinical evidence for lymph node transfer, discuss its proposed functional mechanisms, review the potential risk of iatrogenic lymphedema following this procedure, and discuss the suggested strategies to avoid this complication.
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http://dx.doi.org/10.1097/01.prs.0000475827.94283.56DOI Listing
March 2016

Reply: Scarpa Fascia Preservation in Abdominoplasty: Does It Preserve the Lymphatics?

Plast Reconstr Surg 2016 May;137(5):899e-900e

Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia.

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http://dx.doi.org/10.1097/PRS.0000000000002090DOI Listing
May 2016

The Microvascular Basis of the Superior Thyroid Artery Perforator Flap.

Plast Reconstr Surg 2015 Oct;136(4):849-854

Parkville, Victoria, Australia From the Taylor Laboratory, Department of Anatomy and Neurosciences, University of Melbourne; and the Department of Plastic and Reconstructive Surgery, Royal Melbourne Hospital.

Background: The superior thyroid artery perforator flap has been presented previously in this Journal as a locoregional flap that provides an excellent tissue match with minimal donor morbidity for lateral face and temple defects. In the current study, the authors aimed to describe the microvascular anatomy of this flap.

Methods: The authors used in vivo computer tomographic angiography, cadaveric dissection, and ex vivo angiography in order to improve surgical safety and application of this technique.

Results: The authors provide a detailed map of the microvasculature that is critical to success in this technique, in addition to useful surface anatomical landmarks for ready application in the clinical scenario. Further, the authors discuss the anatomical basis of this flap with reference to the angiosome concept and the critical presence of true anastomoses.

Conclusion: The superior thyroid artery perforator flap has been shown to be an excellent technique for reconstruction of lateral face and temporal soft tissue defects, providing a thin, pliable, hair-bearing tissue with minimal donor morbidity.
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http://dx.doi.org/10.1097/PRS.0000000000001628DOI Listing
October 2015

Scarpa Fascia Preservation in Abdominoplasty: Does It Preserve the Lymphatics?

Plast Reconstr Surg 2015 Aug;136(2):258-262

Parkville, Victoria, Australia From the Department of Anatomy and Neuroscience, University of Melbourne.

Background: The course of the cutaneous lymphatic collectors of the abdominal wall in relation to the Scarpa fascia is unclear in the literature. Preserving the Scarpa fascia in the lower abdomen to reduce the seroma rate following abdominoplasty has been suggested based on the assumption that the lower abdominal lymphatics run deep to this layer along their entire course.

Methods: Using the previously described technique, the superficial lymphatic drainage of eight hemiabdomen specimens from four fresh human cadavers was investigated.

Results: The upper and lower abdominal collectors originated at the umbilical and midline watershed areas in a subdermal plane by the union of precollectors draining the dermis. In the lower abdomen, the depth of the collectors gradually increased in the subcutaneous fat as they coursed toward the groin. They eventually pierced the Scarpa fascia before draining into the superficial inguinal nodes located deep to this layer. The transition from the supra- to the infra-Scarpa fascia plane occurred within 2 to 3 cm of the inguinal ligament in 95 percent of the collectors.

Conclusion: In the four cadavers studied, preserving the Scarpa fascia during abdominoplasty would not preserve the lower abdominal collectors.
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http://dx.doi.org/10.1097/PRS.0000000000001407DOI Listing
August 2015

Autologous fat grafting: current state of the art and critical review: reply.

Ann Plast Surg 2015 May;74(5):633-4

University of Melbourne Parkville, Victoria, Australia.

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http://dx.doi.org/10.1097/SAP.0000000000000489DOI Listing
May 2015

Reply: The vasculosome theory.

Plast Reconstr Surg 2015 Feb;135(2):451e-453e

Department of Anatomy, University of Melbourne, Parkville, Victoria, Australia.

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http://dx.doi.org/10.1097/PRS.0000000000000891DOI Listing
February 2015

Understanding the three-dimensional anatomy of the superficial lymphatics of the limbs.

Plast Reconstr Surg 2014 Nov;134(5):1065-1074

Parkville, Victoria, Australia From Anatomy and Neuroscience, University of Melbourne.

Background: There are minimal data in the current literature regarding the depth of the superficial lymphatic collectors of the limbs in relation to the various subcutaneous tissue layers.

Methods: Injection, microdissection, radiographic, and histologic studies of the superficial lymphatics and the subcutaneous tissues of 32 limbs from 15 human cadavers were performed.

Results: Five layers were consistently identified in the integument of all the upper and lower limb specimens: (1) skin, (2) subcutaneous fat, (3) superficial fascia, (4) loose areolar tissue, and (5) deep fascia. Layer 2 was further divided into superficial (2a) and deep (2c) compartments by a thin, transparent, horizontal septum (layer 2b). The main superficial veins and the superficial nerves coursed in layer 4. The lymphatic collectors were found at layer 2c and layer 4.

Conclusions: The use of consistent nomenclature to describe the subcutaneous tissue layers facilitates a greater understanding and discussion of the anatomy. In lymphovenous anastomosis for the treatment of lymphedema, indocyanine green lymphography is an unreliable method for identification of the superficial collectors of the thigh. The medial proximal leg, the dorsum of the wrist over the anatomical snuffbox, and the volar proximal forearm provide suitable areas for locating superficial collectors with nearby matching size veins. In vertical medial thigh lift, choosing a dissection plane superficial to the great saphenous vein is unlikely to preserve the collectors of the ventromedial bundle.
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http://dx.doi.org/10.1097/PRS.0000000000000640DOI Listing
November 2014

Reply: understanding the fascial supporting network of the breast: key ligamentous structures in breast augmentation and a proposed system of nomenclature.

Plast Reconstr Surg 2014 Aug;134(2):326e-328e

Taylor Laboratory, Department of Anatomy and Neuroscience, University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia.

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http://dx.doi.org/10.1097/PRS.0000000000000542DOI Listing
August 2014

Reply: True and "choke" anastomoses between perforator angiosomes: part I. Anatomical location.

Plast Reconstr Surg 2014 Jun;133(6):891e

University of Melbourne, Parkville, Victoria, Australia.

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http://dx.doi.org/10.1097/PRS.0000000000000229DOI Listing
June 2014

Hydrogen peroxide priming of the venous architecture: a new technique that reveals the underlying anatomical basis for venous complications of DIEP, TRAM, and other abdominal flaps.

Plast Reconstr Surg 2014 Jun;133(6):790e-804e

Parkville, Victoria, Australia From the Taylor Laboratory, Department of Anatomy and Neuroscience, University of Melbourne.

Background: Previous studies of venous anatomy lack the detail of their arterial counterparts because of (1) the technical challenge of retrograde perfusion against competent valves and (2) anterograde venous perfusion failing to adequately delineate the area of interest. We introduced a novel technique: retrograde hydrogen peroxide priming that dilates veins and renders valves incompetent, thereby facilitating complete cadaveric venous perfusion.

Methods: The superficial and deep venous systems of 41 hemiabdomens and 20 hemichests of unembalmed human cadavers were primed by retrograde injection with 6% hydrogen peroxide. Specimens were then injected with lead oxide contrast, radiographed, and dissected. In five hemiabdomens, the valves were mapped by dissection. Results were compared with archival venous studies of six total body injections, six abdominal lipectomy specimens, and two intraoperative venograms of delayed transverse rectus abdominis musculocutaneous flaps.

Results: Unprecedented venous filling of the anterior torso was demonstrated. Two types of superficial-to-deep venous connections were defined: large venae communicantes and small venae comitantes. Venae communicantes (>2 mm) formed major connections between large superficial and deep veins, mostly within 5 cm of the umbilicus in the abdomen, the axilla and fifth or sixth intercostal space parasternally. Seventy-four percent of venae communicantes coursed with arteries greater than 1.0 mm. Four major longitudinal valved subcutaneous pathways of the superficial inferior epigastric vein and superficial circumflex iliac vein were defined bilaterally with large avalvular transverse connections in the midline and small-caliber connections laterally that explain venous complications seen sometimes in transverse abdominal flaps.

Conclusion: Retrograde hydrogen peroxide priming of veins in cadavers renders valves incompetent and facilitates detailed venous studies that help refine flap design and explain venous complications.
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http://dx.doi.org/10.1097/PRS.0000000000000228DOI Listing
June 2014

Understanding the fascial supporting network of the breast: key ligamentous structures in breast augmentation and a proposed system of nomenclature.

Plast Reconstr Surg 2014 Feb;133(2):273-281

Potts Point, New South Wales, Australia From Taylor Laboratory, Department of Anatomy and Neuroscience, University of Melbourne, Royal Melbourne Hospital.

Background: The fascial system of the breast has, to date, only been described in general terms. This anatomical study has developed two distinct methods for better defining existing breast structures such as the inframammary fold, as well as defining previously unnamed ligamentous structures.

Methods: The authors harvested and examined 40 frozen, entire chest wall cadavers. Initially, 15 embalmed cadavers were studied with a combination of blunt and sharp dissection, which proved to be inaccurate. A further 20 fresh and five embalmed chest walls were harvested, frozen, and then sectioned with a bandsaw (3-cm slices) and knife (1.5- to 4-cm slices) depending on the area studied. Sagittal, horizontal, and oblique sections along the length of the ribs were created and then dissolved using either sodium hydroxide or alcohol dehydration followed by xylene immersion. Constant fascial connections between the breast parenchyma, superficial fascia, pectoralis muscle (deep) fascia, and bone were observed.

Results: Specimens clearly demonstrated internal structures responsible for the surface landmarks of the breast. The precise configuration of the infra mammary fold was clearly visible, and new ligamentous structures were identified and named.

Conclusions: Knowing the location and interrelationship of these structures is particularly important in breast augmentation. Reappraisal of the anatomy in this area has enabled precise identification of ligamentous structures in the breast. Correlation of the findings in this article to specific clinical conditions or modes of treatment can be proven only by a clinical series that scientifically addresses the necessity and efficacy of preserving, releasing, or repositioning any of these structures.
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http://dx.doi.org/10.1097/01.prs.0000436798.20047.dcDOI Listing
February 2014

True and 'choke' anastomoses between perforator angiosomes: part II. dynamic thermographic identification.

Plast Reconstr Surg 2013 Dec;132(6):1457-1464

Parkville, Victoria, Australia From the Department of Anatomy and Neuroscience, University of Melbourne.

Background: Cadaveric studies have revealed that cutaneous perforators are linked by either reduced-caliber "choke" arteries, or by vessels without change in caliber, the true anastomoses. These true anastomotic vessels are often found in parallel with the cutaneous nerves and accompanying veins, and are associated both experimentally and clinically with larger areas of flap survival. The Doppler probe and computed tomographic angiography are already used preoperatively to determine perforator locations but currently cannot reveal the type of anastomotic connections.

Methods: Thermal images were taken in a previously described fashion and compared with both computed tomographic angiographic studies where available and with cadaveric angiographic studies previously performed by the authors' laboratory.

Results: Perforators larger than 1 mm were accurately localized by thermography when compared with computed tomographic angiography. Perforator angiosome rewarming closely approximated a log-based line of best fit. Interperforator zones were variable in their rewarming and correlated with known anatomical patterns of true and choke anastomoses between perforator angiosomes.

Conclusions: Thermography now offers a new modality with which to bridge the gap not only by identifying the perforator "hot spots" but also by the robustness of their interconnections. The pattern of these interconnections seen on thermographic imaging has in turn been found to match those seen in the authors' cadaveric studies.
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http://dx.doi.org/10.1097/01.prs.0000434407.73390.82DOI Listing
December 2013

True and 'choke' anastomoses between perforator angiosomes: part i. anatomical location.

Plast Reconstr Surg 2013 Dec;132(6):1447-1456

Parkville, Victoria, Australia From the Department of Anatomy and Neuroscience, University of Melbourne.

Background: Reports of more than two cutaneous perforator angiosome territories being raised successfully in distally based sural flaps are appearing in the literature. Previous anatomical studies have noted that cutaneous arteries, connected by true anastomosis without change in caliber, frequently parallel cutaneous nerves.

Methods: Twenty-four (48 sides) total body lead oxide cadaver injection studies, including seven arterial and two venous neurovascular, were examined, and the results were compared with clinical thermography in Part II.

Results: Long branches of cutaneous perforators, connected in a series by true anastomoses, paralleled at variable distances the main trunks of cutaneous nerves in the head, neck, torso, and upper and lower extremities. Specifically, in the leg, an average of 3.2 true anastomoses (range, 1 to 5) connected perforators that paralleled the sural nerve on the back of the calf; and 2.5 (range, 1 to 4) connected perforators on the medial side of the leg. These vascular freeways were paralleled by the short and long saphenous veins, respectively.

Conclusions: True anastomoses frequently connect skin perforators that course in parallel with cutaneous nerves and veins. They provide an explanation for the long viable flaps noted in the leg, and it will be shown in Part II that they can be detected preoperatively with thermography.
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http://dx.doi.org/10.1097/PRS.0b013e3182a80638DOI Listing
December 2013

A classification system for partial and complete DIEP flap necrosis based on a review of 17,096 DIEP flaps in 693 articles including analysis of 152 total flap failures.

Plast Reconstr Surg 2013 Dec;132(6):1401-1408

Parkville, Victoria, Australia From the Taylor Laboratory, Department of Anatomy and Neuroscience, University of Melbourne, Royal Melbourne Hospital.

Background: In a comprehensive review of 17,096 deep inferior epigastric perforator (DIEP) flaps in 693 articles published between the first description of the DIEP flap in 1989 and August of 2011, the authors found that the methods used to categorize partial necrosis and fat necrosis were inconsistent. As a result, these surgical outcomes cannot be meaningfully compared among series and centers. In contrast, complete flap failure is an unambiguous and universally reported outcome that represents only a portion of the entire spectrum of flap necrosis.

Methods: The authors created a database of every article with data on DIEP flaps by searching PubMed and Embase for the terms "DIEP," "DIEAP," "epigastric AND perforator," "perforator," and "flap AND reconstruction" and manually reviewing the 14,480 citations the search generated. The authors then reviewed 693 articles with data on DIEP flaps for incidence and other clinical details of flap loss, partial necrosis, and fat necrosis.

Results: The authors found a broad range of definitions of partial and fat necrosis based on different parameters (e.g., percentage of flap lost, area of flap lost, necessity of reoperation) that were not directly comparable. Of 152 documented DIEP flap losses, 67 had reported causes: 40 percent (27 of 67) involved venous problems, 28 percent (19 of 67) arterial, and 21 percent (14 of 67) mechanical (pedicle kinking, hematoma).

Conclusions: At present, there is no consensus on the reporting of partial necrosis and flap necrosis. The authors propose a new flap necrosis classification system that prevents ambiguity and allows direct objective comparison of surgical outcomes among centers.
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http://dx.doi.org/10.1097/01.prs.0000434402.06564.bdDOI Listing
December 2013

The anatomical basis for improving the reliability of the supraclavicular flap.

J Plast Reconstr Aesthet Surg 2014 Feb 26;67(2):198-204. Epub 2013 Oct 26.

Taylor Laboratory, Department of Anatomy and Neurosciences, University of Melbourne, Parkville, Victoria, Australia; Department of Plastic and Reconstructive Surgery, Royal Melbourne Hospital, Parkville, Victoria, Australia.

Introduction: The supraclavicular flap has re-emerged as a feasible option for head and neck reconstruction where a thin, pliable donor tissue is required or where free flap techniques may impose too great a surgical risk in frail patients. Whilst our understanding of the vasculature of this flap has improved immensely, the microvasculature and in particular the venous drainage of the distal half of the supraclavicular flap remain relatively unclear. The present study aims to detail the arterial supply and venous drainage of the supraclavicular flap, particularly relating to the interperforator anastomoses.

Methods: The arterial and venous systems of the supraclavicular flap were injected with a radiopaque medium in eighteen fresh cadavers (twenty three and twelve flaps, respectively). Dissected supraclavicular flaps were subjected to plain X-ray imaging plus CT angiography to visualise the arterial and venous systems and relations to surrounding muscle and fascia. Further, the nature of any true or choke anastomoses was described.

Results: The arterial supply of the supraclavicular flap is a combination of axial pattern proximally and random pattern distally, demarcated by the origin of deltoid muscle. The venous system must undergo significant shunting into high pressure vessels once the preferred natural venous pathways are ligated whilst the flap is raised. A vast number of anastomoses, both arterial and venous exist over the body of deltoid and are critical to distal flap tissue survival.

Conclusion: The vascularity of the supraclavicular flap is complex and relies upon relatively small, superficial vessels. This technique is a prototypical example of the angiosome concept at work and thus relies heavily on our understanding of the location and nature of the anastomoses along its course. We conclude that the supraclavicular flap remains a reliable method for reconstructing head and neck defects so long as the constraints of a complicated suprafascial vascular system are respected.
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http://dx.doi.org/10.1016/j.bjps.2013.10.006DOI Listing
February 2014

New perspectives on the surgical anatomy and nomenclature of the temporal region: literature review and dissection study.

Plast Reconstr Surg 2013 Sep;132(3):461e-463e

G. I. Taylor Laboratory, Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia.

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http://dx.doi.org/10.1097/PRS.0b013e31829ad44eDOI Listing
September 2013

Autologous fat grafting: current state of the art and critical review.

Ann Plast Surg 2014 Sep;73(3):352-7

From the *Taylor Laboratory, Department of Anatomy and Neurosciences, University of Melbourne; †Department of Plastic and Reconstructive Surgery, Royal Melbourne Hospital and University of Melbourne, Parkville; and ‡Australian Catholic University, Victoria Pde, Fitzroy, Victoria, Australia.

Background: Despite the widespread use of autologous fat grafting in both reconstructive and cosmetic surgery, volume retention remains a significant problem. We aimed to critically appraise the current body of literature in fat grafting to provide a framework to guide application and comparison.

Method: Search of scientific databases and gray literature was conducted. Articles examining nonadipogenic applications of adipose tissue and those specific to breast reconstruction were excluded.

Results: One hundred three articles were included. These fell under the headings of donor site, effect of infiltration solution, harvest method, effect of centrifugation, reinjection method, supplementation, the role of adipose-derived stem cells, and scaffolding.

Conclusions: Despite the significant research effort in this field, there remains no consensus as to the optimum technique. This stems from the vast array of research methods and short follow-up durations. Further, extrapolation of in vitro results to clinical settings has led to many conflicting practices.
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http://dx.doi.org/10.1097/SAP.0b013e31827aeb51DOI Listing
September 2014

Anatomy of the superficial lymphatics of the abdominal wall and the upper thigh and its implications in lymphatic microsurgery.

J Plast Reconstr Aesthet Surg 2013 Oct 6;66(10):1390-5. Epub 2013 Jun 6.

Taylor Lab, Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia.

Background: The recent advent in the surgical treatment of lymphedema necessitates a more detailed understanding of the anatomy of the lymphatic system. Lymphovenous anastomosis (LVA) requires a precise knowledge of the anatomy of the superficial lymphatic collectors in relation to the superficial veins. In vascularized lymph node transfer (VLNT), donor site lymphatic function must be preserved.

Methods: Using the previously described technique, the superficial lymphatic drainage of 8 anterior hemi-abdomen/upper thigh specimens from 4 fresh human cadavers was investigated.

Results: The upper and lower abdominal collectors were found above Scarpa's fascia immediately below the subdermal venules. They were thin-walled and translucent and their diameter ranged between 0.2 and 0.8 mm. In the upper thigh two distinct groups of superficial collectors were found. The collectors of the ventromedial bundle constituted the majority of the superficial collectors, were deep in the subcutaneous fat, measured 0.6-1 mm in diameter, had thick walls, and consistently drained into two large nodes inferolateral to the saphenous bulb. The local collectors of the thigh were immediately deep to the subdermal venules, measured 0.3-0.5 mm, had thin walls, and drained into the superolateral group of the superficial inguinal nodes which also drained the lower abdomen, the lower back and the upper gluteal region.

Conclusions: When raising the groin lymphatic flap for VLNT, the medial extent of the dissection should be limited to the lateral border of femoral artery. When following up patients after VLNT with a groin donor site, circumference measurements must include the upper thigh.
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http://dx.doi.org/10.1016/j.bjps.2013.05.030DOI Listing
October 2013