(A) Atherosclerotic occlusion of the occipital arteries
(B) Atherosclerotic occlusion of the vertebral arteries
(C) Prior ipsilateral carotid endarterectomy
(D) Prior ipsilateral radical neck dissection
(E) Prior ligation of the ipsilateral circumflex scapular vessels

The correct response is Option D.

The transverse cervical artery, which provides the primary vascular supply to the trapezius flap, is typically divided during an ipsilateral radical neck dissection. Therefore, the trapezius flap cannot be used for coverage of a defect in a patient who has undergone an ipsilateral radical neck dissection because its primarily vascular supply is presumed hes. The anterior branch then courses toward the shoulder, while the posterior branch courses beneath the central portion of the trapezius along its main axis, continuing to supply blood to this flat, triangularly shaped type II muscle.

The occipital artery is a secondary source of vascularity for the trapezius muscle flap. However, in looking at the specific location and depth of this patient's defect, it appears that the portion of the muscle supplied by the occipital artery has been resected. The medial edge of the trapezius flap also receives some blood from posterior thoracic intercostal perforators along the medial edge of the flap.

Because carotid endarterectomy is performed at or close to the bifurcation of the common carotid artery, it does not disrupt the thyrocervical trunk. The circumflex scapular vessels and vertebral arteries are not involved in supplying vascularity to the trapezius flap.

References
1. Hagan KF, Mathes SJ. Trapezius muscle and musculocutaneous flaps. In: Strauch B, Vasconez LO, Hall-Findlay EJ, eds. Grabb's Encyclopedia of Flaps. Boston, Mass: Little, Brown & Co; 1990:496-511.
2. McCraw JB, Arnold PG, eds. McCraw and Arnold's Atlas of Muscle and Musculocutaneous Flaps. Norfolk, Va: Hampton Press Publishing Co; 1988:89-91.

In a patient who has undergone resection of a squamous cell carcinoma of the floor of the mouth, which of the following free flaps will provide vascularized bone and a sensate skin paddle?

(A) Iliac crest flap
(B) Lateral arm flap
(C) Parascapular flap
(D) Serratus anterior flap

The correct response is Option B.

Because the lateral arm flap provides both vascularized bone and a sensate skin paddle, it is best used for reconstruction of this patient's defect involving the floor of the mouth. Vascularity and skin sensibility are provided by the radial collateral artery and posterior brachial cutaneous nerve (C5-6), respectively. As much as 7 cm * 12 cm of skin can be elevated with the flap; in addition, because of its periosteal attachments, as much as one-third of the posterior lateral humerus (or 10 cm to 15 cm in length and 1 cm to 1.5 cm in diameter) can be harvested.

The iliac crest osteocutaneous flap, which is based on the deep circumflex iliac artery, can provide a skin paddle as large as 12 cm * 6 cm and a bone segment as large as 8 cm ( 18 cm. Although this flap can be used for reconstruction of large mandibular segments and extensive soft-tissue defects, the skin component is bulky and insensate. Meticulous closure of the donor site defect is required to prevent hernia formation.

The parascapular flap is based on the circumflex scapular artery. Advantages of this flap include multiple skin paddles, a large segment of bone, and a high degree of independent motion between the skin and bone segments. The serratus anterior and/or latissimus dorsi muscles can be included with the flap to reconstruct complex defects. However, the skin paddles of this flap are also bulky and lack a cutaneous sensory nerve.

The serratus anterior flap is extremely versatile. Skin, muscle, and an iliac bone graft can be included with this flap; its pedicle is long and has a large diameter. It can be harvested as a functional muscle flap with inclusion of the branches of the long thoracic nerve; however, the upper four to five muscle slips must be preserved in order to prevent winging of the scapula. This primary disadvantage of this flap is that any bone incorporated with it will be less substantial and have poor vascularization when compared with other osteocutaneous flaps. The skin component of this flap is also insensate.

References
1. Coleman JJ III, Sultan MR. The bipedicled osteocutaneous scapula flap: a new subscapular system free flap. Plast Reconstr Surg. 1991;87:682-692.
2. Mathes SJ, Nahai F, eds. Reconstructive Surgery. New York, NY: Churchill Livingstone, Inc; 1997:477-500, 617-642, 729-746, 965-984, 1353-1370.
3. Seitz A, Papp S, Papp C, et al. The anatomy of the angular branch of the thoracodorsal artery. Cells Tissues Organs. 1999;164:227-236.
4. Strauch B, Yu HL, eds. Atlas of Microvascular Surgery: Anatomy and Operative Approaches. New York, NY: Thieme Medical Publishers, Inc; 1993:17-21, 154-158, 218-237, 424-425, 504-522.

A 21-year-old man sustains an avulsion injury involving the skin of the dorsal aspect of the right hand. On examination, there is a loss of paratenon; the extensor tendons are exposed. A reverse radial forearm flap is to be used for coverage of the defect.

The venous outflow of this flap depends primarily on which of the following vessels?

(A) Accessory cephalic vein
(B) Basilic vein
(C) Cephalic vein
(D) Radial venae comitantes
(E) Ulnar venae comitantes

The correct response is Option D.

All reverse flaps are based on a "retrograde flow" design, in which the blood flows into the artery and out of the vein, opposing normal physiology. In order for this to occur properly, either the valves of the peripheral veins must be incompetent or the flow of blood must circumvent the valves. The reverse radial forearm flap has small, intercommunicating veins that lie between the paired venae comitantes and act as shunts, bypassing the valves and allowing blood flow directly between the venae comitantes. Thus, retrograde flow is established, and a useful, viable vascularized flap is created.

As long as the paired venae comitantes and intercommunicating veins remain intact, the reverse radial forearm flap can be used to cover large defects involving the dorsal aspect of the hand. Any mechanical separation of the venae comitantes during flap harvest will result in damage to the intercommunicating veins and lead to flap failure. In addition, an Allen's test should be performed preoperatively to demonstrate an adequate retrograde flow of blood from the ulnar artery through the distal artery.

The cephalic vein originates at the radial aspect of the dorsal venous network and flows into the axillary vein. The basilic vein originates ulnarly within the dorsal venous network, joins with the median cubital vein, and ascends medial to the biceps tendon, perforating the deep fascia at the middle of the arm and then continuing as the axillary vein. The median vein of the forearm provides drainage for the superficial palmar venous plexus and ascends on the volar aspect of the forearm to drain into the basilic or median cubital vein. Because these veins and the accessory cephalic vein do not have interconnecting veins that allow for bypass of the valves, reverse flow is prohibited.

The ulnar venae comitantes act in conjunction with the ulnar artery and thus are not involved in the drainage of the reverse radial forearm flap.

References
1. Beimer E, Stack W. Total thumb reconstruction: a one stage reconstruction using an osteocutaneous forearm flap. Br J Plast Surg. 1983;36:52.
2. Martin D, Bakhach J, Casoli V, et al. Reconstruction of the hand with forearm island flaps. Clin Plast Surg. 1997;24:33-35.
3. Soutar DS, Tauner NS. The radial forearm flap in the management of soft tissue injuries of the hand. Br J Plast Surg. 1984;37:18.

A 57-year-old man undergoes composite resection of an advanced squamous cell carcinoma of the retromolar trigone. An osteocutaneous free flap that provides a 6-cm bone segment, intraoral lining, and external skin will be used for reconstruction of the defect.

Which of the following osteocutaneous free flaps will allow for maximum independence in repositioning the skin paddle in relation to the bone segment?

(A) Fibular
(B) Iliac crest
(C) Lateral arm
(D) Radial forearm
(E) Scapular

The correct response is Option E.

Reconstruction in this patient should be performed using the scapular flap, which will provide the greatest degree of leeway in positioning the skin paddle in relation to the bone segment. This is typically advantageous when using the flap to reconstruct complex defects of the head and neck. The scapular flap derives its primary blood supply from the circumflex scapular artery, which originates from the subscapular artery and passes through the triangular space. Branches of the circumflex scapular artery consistently supply the lateral border of the scapula at a point prior to the division of the artery into transverse and descending branches. A 3-cm vascular pedicle extends from the border of the scapula to the overlying skin and allows for an additional three degrees of spatial freedom when insetting the skin paddle. In addition, the angular branch of the thoracodorsal artery has been shown to consistently provide an independent source of perfusion to the inferior pole of the scapula. This allows for a greater arc of rotation between the bone and skin paddle because each portion derives its vascularity from separate sources.

The fibular flap is based on the peroneal artery as well as its multiple periosteal vessels and cutaneous perforators; it can provide as much as 25 cm of bone for mandibular reconstruction. Because of the limited amount of skin that can be harvested with this flap, it is not often used in reconstruction without additional skin grafting; in addition, there is very little freedom in repositioning the skin relative to the bone. Harvest of this flap is contraindicated in patients with several peripheral vascular disease.

The iliac crest osteocutaneous flap, which is based on the deep circumflex iliac artery, can provide a skin paddle as large as 12 cm * 6 cm and a bone segment as large as 8 cm * 18 cm. Although this flap can be used for reconstruction of large mandibular segments and extensive soft-tissue defects, the skin component is bulky and insensate. Meticulous closure of the donor site defect is required to prevent hernia formation.

Advantages of the lateral arm flap include a thin, pliable, sensate skin paddle and the potential harvest of as much as 12 cm of skin and one third of the diameter of the humerus. Because of these factors, the flap is often used for reconstruction of defects of the head and neck or upper extremities. A skin paddle as large as 6 cm can be harvested without skin grafting. However, the use of this flap is once again limited by its lack of freedom between the skin and underlying bone segment.

The radial forearm flap can provide thin, pliable skin and a maximum of 10 cm of bone, which can include a cross-sectional area comprising approximately 40% of the radius. Once again, there is minimal freedom when positioning

References
1. Coleman JJ III, Sultan MR. The bipedicled osteocutaneous scapula flap: a new subscapular system free flap. Plast Reconstr Surg. 1991;87:682-692.
2. Robb GL. Free scapular flap reconstruction of the head and neck. Clin Plast Surg. 1994;21:45-58.
3. Strauch B, Yu HL, eds. Atlas of Microvascular Surgery: Anatomy and Operative Approaches. New York, NY: Thieme Medical Publishers, Inc; 1993:49-58, 142-157, 233-237, 504-517.
4. Swartz WM, Banis JC, Newton ED, et al. The osteocutaneous scapular flap for mandibular and maxillary reconstruction. Plast Reconstr Surg. 1986;77:530.

A 25-year-old woman sustains a contact injury to the posterior aspect of the scalp. Following debridement, she has a 6 * 4-cm defect of the posterior scalp with exposed bone. Which of the following is the most appropriate next step in management?

(A) Excision and primary closure
(B) Full-thickness skin grafting
(C) Coverage with a rotation flap
(D) Hair transplantation
(E) Tissue expansion

The correct response is Option C.

In this 25-year-old woman who has a 6 * 4-cm defect of the posterior aspect of the scalp, the most appropriate management is coverage of the defect using a rotation flap. This flap provides local hair-bearing tissue and can be used to cover defects as large as 6 cm. In order to advance an adequate length of flap, multiple relaxing incisions must be performed within the galea. If the galea is not carefully divided, injury to the subcutaneous vessels or hair follicles may result, leading to the onset of alopecia or delayed wound healing.

Tissue expansion is most appropriate for patients who have large defects of the scalp (typically greater than 15%) because the scalp defect will be covered with similar tissue. Donor site scarring is not a factor in most cases, and the expanders can be left in place if further tissue expansion is required. In addition, the hair follicles will be oriented correctly; as much as 50% of the scalp can be covered with expanded tissue without altering hair growth. However, the process of tissue expansion involves multiple procedures and frequent office visits over a lengthy period of time. During the expansion process, the patient often expresses displeasure with his/her physical appearance.

Excision and primary closure combined with extensive undermining are only appropriate for patients who have defects measuring less than 5 cm. Patients with small areas of scalp alopecia may undergo multiple staged excisions of the alopecic scalp followed by advancement of hair-bearing tissue. Because this process involves fewer procedures and less follow-up, it can be used as an alternative to tissue expansion.

Although a full-thickness skin graft can be used for temporary wound coverage in a patient who will undergo further scalp reconstruction, it is not an appropriate long-term treatment because many donor sites do not provide adequate hair-bearing skin.

Hair transplantation is currently being used with increasing regularity for treatment of traumatic or age-related alopecia.

References
1. Achauer BM. Scalp. In: Burn Reconstruction. New York, NY: Thieme Medical Publishers, Inc; 1991:13-22.
2. Argenta LC, Marks MW, Pasyk KA. Advances in tissue expansion. Clin Plast Surg. 1985;12:159.
3. McCauley RL. Correction of burn alopecia. In: Herndon DN, ed. Total Burn Care. Philadelphia, Pa: WB Saunders Co; 1996:499-502.
4. Oishi SN, Luce EA. The difficult scalp and skull wound. Clin Plast Surg. 1995;22:51-59.

PHOTO

A 39-year-old woman is undergoing breast reconstruction using a superior gluteal artery perforator free flap. An illustration of the donor site is shown in the above photograph. Which of the following best illustrates the point at which the superior gluteal artery emerges from the terminal branch of the internal iliac artery?

(A) Point A
(B) Point B
(C) Point C
(D) Point D
(E) Point E

The correct response is Option A.

The superior gluteal artery, which is a terminal branch of the internal iliac artery, exits lateral and deep to the sacrum above the level of the piriformis muscle and then courses through the gluteus maximus muscle. At this point, the artery branches into many cutaneous perforator arteries, most of which lie within the superolateral gluteal region. In order to determine the exact point at which the superior gluteal artery emerges from the terminal branch of the internal iliac artery, which will determine the appropriate site for flap harvest, a line can be drawn between the posterosuperior iliac spine and the apex of the greater trochanter of the femur. The superior gluteal artery will emerge at the border of the sacrum at the junction of the middle and medial thirds of this line.
The positioning of the piriformis muscle can be determined by drawing a line between the greater trochanter and a point midway between the posterosuperior iliac spine and the coccyx.

References
1. Blondeel PN. The sensate free superior gluteal artery perforator (S-GAP) flap: a valuable alternative in autologous breast reconstruction. Br J Plast Surg. 1999;52:185.
2. Verpaele AM, Blondeel PN, Van Landuyt K, et al. The superior gluteal artery perforator flap: an additional tool in the treatment of sacral pressure sores. Br J Plast Surg. 1999;52:385.

Which of the following structures provides motor innervation to the gracilis free muscle flap?

(A) Anterior branch of the obturator nerve
(B) Femoral nerve
(C) Inferior branch of the superior gluteal nerve
(D) Medial femoral cutaneous nerve
(E) Median sural nerve

The correct response is Option A.

The anterior branch of the obturator nerve provides motor innervation to the gracilis free muscle flap. This nerve branch courses between the adductor longus and adductor brevis tendons to innervate the gracilis muscle.

The femoral nerve innervates the rectus femoris muscle at the level of the thigh, while the inferior branch of the superior gluteal nerve supplies motor innervation to the tensor fascia lata. The medial femoral cutaneous nerve, which is a branch of the femoral nerve, supplies sensory innervation to the medial thigh flap. The median sural nerve is found below the knee and courses parallel to the lesser saphenous vein.

References
1. Doi K, Sakai K, Kuwata N, et al. Double free-muscle transfer to restore prehension following complete brachial plexus avulsion. J Hand Surg. 1995;20A:408.
2. Strauch B, Han-Liang Y, eds. Atlas of Microvascular Surgery: Anatomy and Operative Approaches. New York, NY: Thieme Medical Publishers, Inc; 1993:166.

A vastus lateralis muscle flap elevated on its dominant pedicle provides reliable coverage for each of the following anatomic sites EXCEPT the

(A) acetabulum
(B) groin
(C) knee
(D) perineum
(E) trochanter

The correct response is Option C.

When the vastus lateralis flap is based on its dominant pedicle, the descending branch of the lateral femoral circumflex artery, it has an area of rotation that will provide vascularized coverage of the lower abdomen, groin, perineum, ischium, trochanter, and acetabular fossa. However, the flap must be reversed in order to rotate and provide coverage of knee defects. When used in this manner, the flap is then based on a branch of the lateral genicular artery, which is a minor distal pedicle. Because the risk for partial flap loss is greater, this flap is not often advocated for coverage of knee defects.

References
1. Bovet JL, Nassif TM, Guimberteau JC, et al. The vastus lateralis musculocutaneous flap in the repair of trochanteric pressure sores: technique and indications. Plast Reconstr Surg. 1982;69:830.
2. Dowden RV, McCraw JB. The vastus lateralis muscle flap: technique and applications. Ann Plast Surg. 1980;4:396.
3. Swartz WM, Ramasastry SS, McGill JR, et al. Distally based vastus lateralis muscle flap for coverage of wounds about the knee. Plast Reconstr Surg. 1987;80:255.

Each of the following is an effective technique for continuous postoperative free flap monitoring EXCEPT

(A) differential surface temperature monitoring
(B) external Doppler ultrasonography
(C) intravenous injection of fluorescein
(D) laser Doppler ultrasonography
(E) photoplethysmography

The correct response is Option C.

Although fluorescein 15 mg/kg is often administered intravenously to determine the viability of a flap's skin paddles, this cannot be used for continuous free flap monitoring because fluorescein often takes several hours to clear from the skin. Lower doses of fluorescein can be used for sequential monitoring, but not for continuous monitoring.

Each of the other options listed can be used for continuous flap monitoring. Although external Doppler ultrasonography is the most frequent choice for flap monitoring, difficulties can be experienced when the flap pedicle is located close to a large artery. External Doppler ultrasonography also cannot be used with buried flaps. Differential surface temperature monitoring compares the temperature of the transferred tissue with the normal surrounding tissue. A temperature difference of greater than 1.8%C (35.3%F) is believed to be significant. Laser Doppler ultrasonography and photoplethysmography both involve the measurement of reflected light from a source that penetrates the flap.

References
1. Jones NF. Intraoperative and postoperative monitoring of microsurgical free tissue transfers. Clin Plast Surg. 1992;19:783-797.
2. McCraw JB, Myers B, Shanklin KD. The value of fluorescein in predicting the viability of arterialized flaps. Plast Reconstr Surg. 1977;60:710-719.

PHOTO

A 25-year-old man sustains an extravasation injury of the dorsal aspect of the wrist. Following debridement, the extensor tendons are exposed; a photograph is shown above. Findings on Allen's test demonstrate radial dominance. Which of the following is the most appropriate next step in management?

(A) Dressing changes and healing by second intention
(B) Split-thickness skin grafting
(C) Coverage with a free lateral arm flap
(D) Coverage with a free rectus abdominis muscle flap and split-thickness skin graft
(E) Coverage with a reverse radial forearm flap

The correct response is Option C.

In this patient who has exposure of the tendons and loss of paratenon after sustaining a wrist injury, the most appropriate management is coverage of the defect using a free lateral arm flap. This is a pliable fasciocutaneous flap that will provide durable coverage of this patient's defect with optimal cosmetic results and minimal donor site morbidity. Its good gliding surface will permit tendon gliding without tethering. If tethering were to occur subsequently, a secondary tenolysis could be easily performed underneath this thin flap.

Dressing changes and healing by second intention are not appropriate in a patient with exposed tendons because tendon adhesions and/or dessication will result. In the same way, the defect should not be covered with a split-thickness skin graft, which will not take when placed directly on top of exposed tendon. Coverage with a free rectus abdominis flap will be bulky and can result in tethering. Secondary tenolysis will be difficult under this flap. The reverse radial forearm flap has been linked to the development of hand ischemia in patients who demonstrate radial dominance on Allen's testing.

References
1. Carlton JM, McGrath MH, Goldberg NH. Skin grafts and pedicle flaps. In: Peimer CA, ed. Surgery of the Hand and Upper Extremity. New York, NY: McGraw-Hill; 1996;2:1819-1844.
2. Jones NF, Lister GD. Free skin and composite flaps. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;2:1159-1200.