Blood Supply of the Rat Biceps Femoris Musculocutaneous Flap

A variety of muscular or musculocutaneous flaps have been developed for clinical and basic science experiments in rats. The rat biceps femoris musculocutaneous flap was first described by Akyürek et al, has many advantages, and adds to the armamentarium of the plastic surgeons involved in flap research.[1] [2] Akyürek et al stated that the flap vascular pedicle nourishes the biceps femoris muscle via two terminal branches: one that goes directly to the muscle and another that goes to a fat pad. However, muscle necrosis is generally confined to the distal part of the flap.[1] We performed latex perfusions of 10 Wistar rats, and we identified a blood supply to the biceps femoris, which is different from previous descriptions. The study protocol was approved by the Shanghai Jiaotong University Medical Center Institutional Animal Care and Use Committee.

We found that four vessels generally supplied the biceps femoris muscle flap. The most superior vessel invariantly arose from the lateral superior genicular artery, which is the first branch of the caudal femoral artery. The other three originated from the trunk of the caudal femoral artery. The second vessel arose from approximately the same level as the common trunk of the external and internal sural arteries and entered the biceps femoris adjacent to the common peroneal nerve. The third vessel primarily arose from the middle point of the second artery and the terminal branches. There were usually two or three terminal branches of the caudal femoral artery that distributed blood to the biceps femoris. The general vascularity pattern that supplies the biceps femoris is shown in [Fig. 1]. The variations in the vascularities across the 20 limbs studied included an absence or a lower take off of the third artery (15%) and different take offs of the first and second arteries (20%, [Fig. 2]).

Fig. 1 (A) During flap harvest, note the typical four terminal branches supplying the femoris biceps; (B) After flap harvest, note the lower take off of the third branch, one of the variations illustrated in [Fig. 2]; (C) perforator artery supplying the skin part of the flap.

Fig. 2 Vascular pattern variations of the biceps femoris flap, red line, caudal femoral artery and the lateral superior genicular artery; green line, first artery to the flap; purple line, second artery to the flap; yellow line, third artery; light blue, fourth artery; dark blue, common peroneal nerve; and light red area, biceps femoris.

A good flap model should have sufficient pedicle length, proper pedicle vessel diameters, and should be easy to harvest. In addition to the biceps flap, other established muscular flaps included the gastrocnemius, latissimus, serratus anterior, gracilis, thigh adductor, abdominal wall, rectus abdominis, abdominal wall, pectoralis major, and quadriceps flaps.[3] Some of these flaps, including the gracilis (pedicle length: 7 mm), pectoralis major (9 mm), and the quadriceps (6 mm) have short pedicles. Some of these flaps, including the latissimus, serratus anterior, pectoralis major (the pedicles of which are thoracodorsal or lateral thoracic vessels), and the abdominal wall flap (the pedicles of which are the iliac vessels) are difficult to harvest because the vessels near the fossa axillaris (i.e., the thoracodorsal or lateral thoracic vessels) and above the inguinal ligament (i.e., the iliac vessels) are complicated.[4] Some of these flaps have small pedicle vessel diameters including the thigh adductor flap supplied by saphenous vessels (0.35–0.55 mm) and the rectus abdominis flap supplied by the superior epigastric vessels (0.4–0.5 mm). Established myocutaneous flaps include the gracilis, cutaneous trunci, and the rectus abdominus flaps.[3] In addition to the disadvantages of the gracilis and rectus abdominus flaps mentioned above, the cutaneous trunci flap also has a relatively short pedicle (1 cm) and receives its blood supply from the lateral thoracic vessels (near the fossa axillaris).[5] The gastrocnemius flap is the only flap with good pedicle length, proper vessel diameters, and good pedicle locations. The biceps flap presented here also fulfills the three aforementioned criteria; this flap has a pedicle length of ∼3 cm, its vessels are over 1 mm in diameter, and it is supplied by the superficial and straight femoral vessels. Furthermore, the biceps flap can be raised as either a muscular flap or a myocutaneous flap. However, it is difficult to dissect the terminal vessels that supply this flap during the harvest of the flap because they are small, fragile, and pass through the popliteal fat pad.

Greene reported that the rat biceps femoris receives its blood supply from the following six vessels: the medial femoral circumflex artery, the posterior scrotal artery, the inferior gluteal artery, the superior muscular branch of the popliteal artery (here termed the caudal femoral artery), the lateral superior genicular artery, and the lateral inferior genicular artery.[4] The former three arteries from the hypogastric trunk (the internal iliac artery) in the rat; they are technically too high to be included in this flap. The lateral inferior genicular artery supplies a small area of the biceps (the lateral superior corner). Thus, the preservation of the blood supplies from the caudal femoral artery and the lateral superior genicular artery is essential for flap survival in this model. Akyürek et al performed valuable work in this flap. However, Akyürek et al did not discuss the lateral superior genicular artery or the second and third arteries described here. The omission of some of the four vessels might be attributable to the partial necrosis that occurred in their biceps femoris musculocutaneous flap. All of these branches are small and wrapped in the popliteal fossa fat pad, which make them highly susceptible to damage during vascular dissection. Our findings here might help us to better preserve these vessels during flap harvest and promote the application of another easy-to-use flap for flap-related experiments.

Author Contribution

Qing Feng Li and Hainan Zhu contributed in research design. LingLing Shen and Hainan Zhu contributed in the writing of the article. Feng Xie and Hainan Zhu contributed in conducting the research.

• References

• 1 Akyürek M, Safak T, Manavbaşi I, Keçik A. A rat musculocutaneous flap model: the biceps femoris musculocutaneous flap. Ann Plast Surg 2000; 45 (3) 305-312
• 2 Ozkan O, Akyürek M, Safak T, Acar B, Ozgentaş HE, Keçik A. Neuromuscular and neuromusculocutaneous flaps in the rat. J Plast Reconstr Aesthet Surg 2006; 59 (3) 279-290
• 3 Zhang F, Sones WD, Lineaweaver WC. Microsurgical flap models in the rat. J Reconstr Microsurg 2001; 17 (3) 211-221 Review
• 4 Greene EC. Anatomy of the Rat. New Jersey, PA: Haddon Craftsmen Inc.; 1935
• 5 Werker PM, Kon M. Cutaneous trunci myocutaneous flap: a new and reliable model for muscle free flap research in the rat. Microsurgery 1992; 13 (4) 204-207