Microvascular free tissue transfer: results in 57 consecutive cases

Locoregional Flap Reconstruction Following Oromaxillofacial Oncologic Surgery in Dogs and Cats: A Review and Decisional Algorithm

Primary treatment of most oromaxillofacial tumors in dogs and cats is resective surgery. Management of malignant tumors may be very challenging as wide/radical free-margin surgical removal must be achieved while preserving vital functions. Removal of orofacial tumors may result in large defects exposing the oral cavity or creating a communication with the nasal, pharyngeal, or orbital cavities. Such defects require orofacial reconstruction in order to restore respiratory and manducatory functions. The veterinary surgeon must be familiar with reconstructive techniques in order to prevent the inability of closing the defect, which could lead to an insufficient resection. Small oral defects exposing the nasal cavity are best closed with local random mucosal flaps. Closure of large oral defects may be better achieved with a facial or major palatine-based axial-pattern flap. Small to moderate facial defects can be closed with local advancement or transposition skin flaps. Reconstruction of large facial defects often requires the use of locoregional axial pattern flaps such as the caudal auricular, the superficial temporal, or the facial (angularis oris) myocutaneous axial pattern flaps. Recent publications have shown that the facial (angularis oris) flap is a very versatile and reliable flap in orofacial reconstructive surgery. A surgical decision algorithm based on the size, nature, and location of the defect is proposed.

Repair of a canine forelimb skin deficit by microvascular transfer of a caudal superficial epigastric flap

Extensive skin loss from the forelimb of a Border collie was repaired by a microvascular caudal superficial epigastric flap, with secondary meshing of the flap to increase coverage. The caudal superficial epigastric artery and vein were anastomosed to the brachial artery and vein. End-to-end anastomosis to the brachial artery and vein did not compromise peripheral blood flow, and no flap necrosis was observed after subsequent limited meshing of the flap.

Surgical treatment of an elbow hygroma utilizing microvascular free muscle transfer in a newfoundland

Microvascular free muscle transfer utilizing the rectus abdominis muscle, in combination with a mesh skin graft and transarticular external fixator, were used following the surgical excision of an elbow hygroma in a Newfoundland dog. Postoperatively, the dog did well with minimal complications and has yet to have a recurrence 10 months following surgery. This report describes the utility and successful use of the rectus abdominis free tissue transfer in the surgical correction of a difficult elbow hygroma in the dog.

Reconstruction of a Nonhealing Lick Granuloma in a Dog Using a Phalangeal Fillet Technique

A 6.5-year-old, castrated male Dalmatian was presented with a 3-month history of a chronic, nonhealing wound related to a previously excised lick granuloma. Reconstruction of the wound on the lateral metatarsal region was achieved using a phalangeal fillet technique, without digital pad transposition. The skin flap healed successfully with very good cosmetic and functional results.

Rectus Abdominis Free Muscle Flap for Reconstruction in Nine Dogs

OBJECTIVE

To evaluate the clinical use and outcome of a rectus abdominis microvascular free flap for wound closure in dogs.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n=9) with complex extremity or oral wounds.

METHODS

Medical records (2002-2006) of dogs that had a rectus abdominis free tissue transfer to close an extremity or oral wound were reviewed.

RESULTS

Nine dogs were identified: 5 had distal extremity wounds, 3 had oral palatal defects, and 1 had a large hygroma excised. A rectus abdominis free tissue transfer with a caudal epigastric vascular pedicle was successfully used for management of these wounds. No major complications occurred with the donor site and a good cosmetic and functional outcome occurred in all dogs.

CONCLUSION

The rectus abdominis is a versatile muscle that can be used for reconstructing cutaneous and oral defects with repeatable success.

CLINICAL RELEVANCE

Free tissue transfer of the rectus abdominis muscle is a clinically useful technique for closure of a variety of difficult soft tissue wounds.

Distal limb and paw injuries

Distal limb reconstruction is complicated by the paucity of local tissues and the frequent association of orthopedic injury with cutaneous loss. Second-intention healing or skin stretching techniques are used for wounds involving less than a 30% circumference of the limb. Skin grafts are recommended for reconstruction of larger superficial wounds after establishing a bed of granulation tissue or for immediate reconstruction of clean wounds overlying healthy muscle. Wounds complicated by orthopedic injury benefit from early reconstruction using vascularized tis-sue. Weight-bearing surface reconstruction and management of partial amputation injuries are functionally difficult because of the environmental stress placed on the paw pads. Paw pad grafts, paw pad transposition techniques, centralization of digits, and microvascular free tissue trans-fer of paw pads can be considered for weight-bearing surface reconstruction. Definitive guidelines describing when each of these techniques should be used have not been established.

Surgical Approaches to Recipient Vessels of the Fore- and HindLimbs for Microvascular Free Tissue Transfer in Dogs

OBJECTIVE

To develop and evaluate surgical approaches to the arteries and veins of the fore- and hindlimbs for use as potential recipient vessels for free tissue transfer.

STUDY DESIGN

Experimental anatomic study.

SAMPLE POPULATION

Canine cadavers (11): 2 preserved and 9 fresh cadavers.

METHODS

Fore- and hindlimbs from 1 preserved cadaver injected with a pigmented silicone/barium mixture, through the common carotid artery and external jugular vein, were cut in 1 cm cross-sections. Tissue sections were used to identify the location of vessels >1 mm that could be used as recipient vessels for free tissue transfer. The other preserved cadaver was used to develop surgical approaches to these vessels. Three surgeons evaluated the written descriptions and illustrations for these approaches using fresh cadavers. Modifications to the surgical approaches were made based on recommendations from these surgeons.

RESULTS

Six approaches were developed to isolate forelimb recipient vessels: palmar access, distal medial antebrachial, mid-antebrachial, proximal antebrachial, distal humeral, and mid-humeral vascular access. Twelve approaches were developed to isolate recipient vessels of the hindlimb: plantar access, dorsal tarsal, cranial distal tibial, craniomedial distal tibial, lateral distal tibial, medial distal tibial, medial femorotibial, lateral distal femoral, medial femoral, proximal medial femoral, groin, and proximal lateral femoral vascular access.

CONCLUSIONS

Six forelimb and 12 hindlimb sites were identified for surgical access to recipient vessels (>1 mm diameter) suitable for use in free tissue transfer for wound reconstruction.

CLINICAL RELEVANCE

For reconstruction of complex wounds of the extremities of dogs, surgeons should consider use of readily accessible recipient vessels that would allow for free tissue transfer to the fore- and hindlimbs.

Use of a Semitendinosus Myocutaneous Flap for Soft-Tissue Reconstruction of a Grade IIIB Open Tibial Fracture in a Dog

OBJECTIVE

To describe the clinical use of a semitendinosus myocutaneous flap for soft-tissue reconstruction of a grade IIIB open tibial fracture.

STUDY DESIGN

Case report.

ANIMALS

A 5-year-old castrated male Labrador retriever with a grade IIIB open tibial fracture.

METHODS

A myocutaneous flap was created by elevating the origin of the semitendinosus muscle and the associated overlying skin. The flap was rotated distally based on the distal vascular pedicle into a soft-tissue defect overlying the central and distal third of the tibia.

RESULTS

The flap allowed one-stage reconstruction of a severe soft-tissue defect overlying denuded bone in a grade IIIB open tibial fracture. The muscular portion of the flap survived; however, there was necrosis of 3 cm of skin extending distally beyond the muscular portion of the flap.

CONCLUSION

Distal rotation of the semitendinosus muscle and overlying skin can be used in the treatment of severe soft-tissue defects of the canine crus.

CLINICAL RELEVANCE

Complex soft-tissue injuries to the canine crus can be treated with a myocutaneous flap as a reasonable alternative to other reconstructive techniques.

Evaluation of primary critical ischemia time for the deep circumflex iliac cutaneous flap in cats

OBJECTIVE

To evaluate the primary critical ischemia time for the deep circumflex iliac (DCI) cutaneous flap in cats.

STUDY DESIGN

In vivo model.

ANIMALS

Thirteen young adult female cats.

METHODS

An island skin flap was created on the right side of each cat based on the angiosome of the ventral branches of the DCI vessels. The cats were randomly assigned to a flap ischemia time ranging from 1 to 3 hours in 10-minute intervals. Microvascular clamps were used to occlude the artery and vein for the designated time. Flaps were sutured into position after the ischemic period. On day 3, fluorescein dye was administered and the flaps were evaluated under ultraviolet light to assess percent area of perfusion. On days 7 and 14, the percent area of survival was determined for each flap based on cutaneous morphometry.

RESULTS

All flaps had 100 percent area of survival throughout the study. On day 3, all flaps fluoresced uniformly compared with the surrounding skin. On days 7 and 14, all flaps were uniformly viable as confirmed by skin color, consistency, bleeding, and hair re-growth.

CONCLUSION

The DCI cutaneous flap in cats can withstand up to 3 hours of ischemia with predictable survival.

CLINICAL RELEVANCE

In a clinical setting, high success rates can be expected with microvascular transfer of the DCI cutaneous flap in cats when the ischemia time is <3 hours and precise surgical technique is used.

Surgical approaches to recipient vessels of the head and neck for microvascular free tissue transfer in dogs

OBJECTIVE

To develop and evaluate surgical approaches to the arteries and veins of the head and neck for use as potential recipient vessels for free tissue transfer.

STUDY DESIGN

Experimental anatomic study.

SAMPLE POPULATION

Eleven canine cadavers; 2 preserved cadavers and 9 fresh cadavers.

METHODS

The head and neck of one preserved cadaver injected with pigmented silicone/barium, through the common carotid artery and external jugular vein, was cut in 1 cm sagittal sections and cross-sections. These tissue sections were used to identify the location of recipient vessels >1 mm that could be used as recipient vessels for free tissue transfer. The other preserved cadaver was used to develop surgical approaches to these vessels. Three board certified surgeons evaluated the written descriptions and illustrations of the approaches using fresh cadavers. Modifications to the surgical approaches were made based on recommendations from these surgeons.

RESULTS

Seven approaches were developed to isolate recipient vessels of the head and neck region. The infraorbital, temporal, and sublingual approaches were easily performed and provided excellent access to the vessels in the region. The approach to the caudal auricular vessels was found to be more difficult but modification of the approach resolved this problem. Access to the facial artery was difficult; it was consistently <1 mm in diameter and thus its use could not be recommended. The approach to the vessels in the cervical region was easily performed. Because of the large size of the external jugular vein and the common carotid artery, end-to-side anastomosis of the donor to recipient vessels is necessary. The large superficial cervical vessels were easily accessed by a lateral shoulder approach.

CONCLUSIONS

Surgical approaches to potential recipient vessels of the head and neck were consistently achieved and provided relatively easy access to the vessels. Clinical Relevance- The surgical approaches described in this report can be used to isolate arteries and veins of the head and neck that are >1 mm in diameter. These vessels are suitable for use as recipient vessels for free tissue transfer for reconstruction of complex wounds of the head and neck.

Deep circumflex iliac cutaneous free flap in cats

OBJECTIVE

To develop and assess the survival of a microvascular cutaneous free flap based on the ventral branch of the deep circumflex iliac (DCI) artery and vein in cats.

STUDY DESIGN

Experimental study.

ANIMALS

Phase 1: 6 feline cadavers; Phase 2: 2 adult cats; Phase 3: 10 adult cats.

METHODS

Phase 1: Selective angiographic study of the deep circumflex iliac artery was completed in 6 feline cadavers. After injection of the DCI artery with barium, high-detail radiographs were made of skin flaps harvested from the lateral flank and thigh region. The extent of the cutaneous angiosome was mapped with regard to the underlying anatomical landmarks. Phase 2: An island flap based on anatomic boundaries of the DCI angiosome derived from phase 1 of the study was elevated in 2 cats. Flaps were observed for 3 weeks for survival. Phase 3: Free skin flaps based on the DCI vessels were harvested in 10 cats and transferred to the dorsal interscapular region. Flaps were evaluated for 2 weeks for survival. Tissue samples were collected for histopathology, and angiograms of the flaps were completed.

RESULTS

Phase 1: Angiograms revealed a large primary cutaneous angiosome of the DCI artery located over the lateral femoral region, which extended from the iliac crest to the level of the patella. Phase 2: All island flaps survived for 3 weeks. Phase 3: Six free flaps survived for 2 weeks, and 4 flaps failed completely. Failure of 1 flap occurred because of avulsion of the venous and arterial anastomosis postoperatively. Another cat had intraoperative hemorrhage, which resulted in anemia and hypovolemia and likely caused the flap to fail. The other 2 flaps that failed had poor perfusion intraoperatively and had the longest ischemia times.

CONCLUSIONS

The cutaneous DCI free flap in cats may be clinically useful in reconstruction of large cutaneous wounds. The length of ischemia time for successful cutaneous free flap transfer in the cat may be shorter than in other species.

CLINICAL RELEVANCE

Large wounds created by trauma or oncologic ablative surgery in cats could be reconstructed with cutaneous microvascular free flap. Additional studies assessing the critical ischemia time of cutaneous flaps in cats and evaluating the use of this flap clinically are needed.

The effect of a porcine-derived small intestinal submucosa product on wounds with exposed bone in dogs

OBJECTIVE

To determine the effect of a porcine-derived small intestinal submucosa product (PSIS) on healing time, epithelialization, angiogenesis, contraction, and inflammation of wounds with exposed bone on the distal aspect of the limbs of dogs.

STUDY DESIGN

Prospective, controlled, experimental study.

ANIMAL POPULATION

10 young adult, purpose-bred, male Beagles.

METHODS

Small wounds with exposed bone were created on the lateral aspect of metatarsal V and the medial aspect of metatarsal II on both hindlimbs. Three sheets of PSIS were sutured into the wounds of the treated limb, and the other limb served as a control. On day 10, punch biopsies of the medial metatarsal wounds were collected and were evaluated microscopically after routine hematoxylin and eosin and phosphotungstic acid hematoxylin (PTAH) staining. The lateral metatarsal wounds were evaluated by planimetry and laser Doppler perfusion imaging on days 7, 14, and 21. Time until complete wound healing was also recorded. The level of significance was set at P < or =.05 for all statistical analyses.

RESULTS

Laser Doppler perfusion measurements were significantly higher in control wounds on day 7, but no differences were noted on days 14 and 21. No significant differences in planimetric values, histopathologic appearance, or time until complete wound healing were noted among treated and control groups.

CONCLUSIONS

No objective differences in healing were noted between control wounds and wounds treated with PSIS.

CLINICAL RELEVANCE

There appears to be no contraindication to the use of PSIS on clean wounds with exposed bone on the distal limbs of dogs. However, our objective data provides no evidence that this product affects epithelialization, contraction, or time to complete healing in wounds with exposed bone.

Microvascular free tissue transfer of the rectus abdominis muscle in dogs

OBJECTIVE

To assess donor-site morbidity and survival of the rectus abdominis muscle with an overlying skin graft after free tissue transfer to a medial femorotibial defect in dogs.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Phase 1: 6 canine cadavers; phase 2: 7 adult mixed-breed dogs.

METHODS

Phase 1: The rectus abdominis muscle was removed from canine cadavers, muscular and vascular dimensions were recorded, and angiography was performed. Phase 2: Muscular transfer was performed through anastomosis of the caudal epigastric artery and vein to the saphenous artery and medial saphenous vein. Transferred tissues were evaluated on postoperative days 3, 6, 10, and 13. Animals were examined daily until euthanasia between postoperative days 31 and 42. Postmortem angiograms were performed and tissues collected for histopathologic evaluation.

RESULTS

Phase 1: Appropriate vascular dimensions for microvascular anastomosis were confirmed and surgical technique perfected. Phase 2: Muscular excision produced minimal donor-site morbidity. All muscles survived after microvascular transfer and angiography confirmed vascular patency. All of the skin grafts survived, with one graft undergoing partial necrosis.

CONCLUSIONS

The rectus abdominis muscle can be successfully transferred to a medial femorotibial defect and can serve as a bed for acute skin grafting. No significant donor-site morbidity is associated with its removal.

CLINICAL RELEVANCE

Microvascular free tissue transfer of the canine rectus abdominis muscle has not been previously described. This technique provides a new alternative for repair of appropriate wounds. Additional studies are needed to define its utility in clinical patients.

Effects of epidural anesthesia on microcirculatory blood flow in free medial saphenous fasciocutaneous flaps in dogs

OBJECTIVE

To assess the effects of epidural anesthesia using lidocaine on microcirculatory blood flow, volume, and velocity in free fasciocutaneous flaps in dogs. Study Design-In vivo experimental investigation. Animal Population-Ten adult dogs weighing 20 to 25 kg.

METHODS

A medial saphenous fasciocutaneous free flap was removed and an orthotopic transfer was performed by anastomosing the primary flap vessels back to the medial saphenous vessels. Blood flow (mL(LD)/min/100 g), volume (%volume or tissue hematocrit) and velocity (mm/s) in the flap were recorded throughout the procedure. After epidural anesthesia, blood flow, volume, and velocity values were again recorded.

RESULTS

Microcirculatory blood flow, volume, and velocity, as measured by a laser-Doppler flowmeter, failed to reveal any significant changes over time. Immediately after epidural anesthesia, mean arterial pressure was significantly reduced and remained depressed throughout the experimental procedure.

CONCLUSIONS

Epidural anesthesia combined with general anesthesia does not improve microcirculatory flow in free flaps in the pelvic limbs of dogs. No significant change in blood flow to the medial saphenous fasciocutaneous free flap occurred after division and anastomosis of the vascular pedicle.

CLINICAL RELEVANCE

We recommend that epidural anesthesia with 2% lidocaine be used with caution in dogs undergoing microvascular free-flap transfer.