Evaluating The Efficacy Of A Bilobed Flap For Reconstruction Of The Hallux

The bilobed flap is a transposition flap made up of two flaps that are separated by an angle and share a common pedicle. Physicians have traditionally used bilobed flaps for facial reconstruction, most commonly following carcinoma excision.^1,2 However, there has been little literature describing the use and effectiveness of bilobed flaps for soft tissue defects about the pedal digits, specifically the hallux.

We present the case of a 61-year-old man with a chronic history of recurrent and recalcitrant cutaneous cyst formation to the left dorsal hallux. The patient opted for surgical excision of the cyst following a period of conservative treatments. In this setting we decided to use a bilobed cutaneous flap with surgical excision of the cyst.

According to the most recent literature for pedal flaps, defects that are located on the dorsal foot require different strategies than those located on the plantar surface.^3,4 The dorsal surface of the foot contains superficial nerves and the extensor tendons covered by thin, mobile skin. In contrast, the plantar surface has thick, relatively immobile, glabrous skin, subcutaneous fat, and neurovascular structures. A variety of flap options provide stable soft tissue coverage.⁵ However, dorsal cutaneous reconstruction requires thinner skin in order to permit tendon excursion while plantar reconstruction provides thick skin and fat, particularly for the weightbearing heel and metatarsal regions. Physicians most often use split thickness skin grafting on the dorsal surface while local flaps or free tissue transfer are optimal for the plantar surface.

Blume and colleagues described the use of a bilobed flap for excision of recurrent digital mucoid cysts in 2005.⁶ This retrospective review described the utility of a bilobed flap in conjunction with resection of the head of the middle phalanx for mucoid cyst pathology. In the study, there were no recurrences, flap failures or significant complications with this technique. The bilobed flap allowed for greater exposure than traditional semi-elliptical incisions while providing a template for wide excision of the defect and primary closure.

Jager and coworkers published on the Zitelli design for bilobed flaps.⁷ The retrospective review examined the application of bilobed flaps on skin defects after digital mucoid cyst excision. The authors also described the unique indication in the geometric design, which allows for fast wound healing and excellent outcomes. The design is easy, safe and reproducible.

Due to the proximity to the junction of the dorsal and plantar skin, a bilobed flap was the flap of choice in this 61-year-old patient in order to permit immediate closure of the primary cutaneous defect. Following excision of the cyst, a midline based bilobed flap was drawn out due to its proximity to thicker, glabrous skin with the main substance of the flap transposing dorsally to take advantage of the thinner, more mobile tissues. The dissection and transposition of the flap were medial to the long extensor tendon to the hallux to avoid compromise of the extensor tendon and superficial to the deep fascia in order to preserve the extensor apparatus. The transposed flap was secured in place with a combination of 4-0 and 6-0 monofilament suture in simple and continuous techniques, respectively. The hallux was dressed with xeroform and a dry sterile dressing. The patient was permitted to remain weightbearing as tolerated in a surgical shoe for two weeks with a return to normal shoe gear at three weeks following the removal of the sutures.

Optimal flap reconstruction, regardless of location, will maintain or restore similar tissue composition, function and aesthetic appearance. Considerations for tissue composition includes the quality and thickness of the skin, and ideally, the underlying structures such as nerves, blood vessels, muscle, cartilage and bone. However, functional maintenance or restoration is perhaps the most important factor for addressing defects involving the foot and ankle.⁸

Proper surgical planning should employ attentiveness to the anatomy and vascularity of individual defects and flaps. Give special considerations to dorsal versus plantar pedal skin. The surgeon should recognize that both types present advantages and disadvantages for consideration to use flaps, tissue grafts or split thickness skin grafts.

Only with a thorough knowledge of anatomy and the applications available within the plastics reconstructive ladder can we properly implement treatments for pedal digital soft tissue reconstruction.

References

1. Sanchez-Conejo-Mir J, Buneo Montes J, Moreno Giminez JC, Camacho-Martinez F. The bilobed flap in sole surgery. J Dermatol Surg Oncol. 1985; 11(9):913-7.

2. Baker SR. Principles of Nasal Reconstruction. Springer, New York, 2011

3. Attinger CE, Ducic I, Zelen C. The use of local muscle flaps in foot and ankle reconstruction. Clin Podiatr Med Surg. 2000;17(4):681–711.

4. Yucel A, Senyuva C, Aydin Y, et al. Soft-tissue reconstruction of sole and heel defects with free tissue transfers. Ann Plast Surg. 2000;44(3):259–69.

5. Van Aalst JA, McCurry T, Wagner J. Reconstructive considerations in the surgical management of melanoma. Surg Clin N Am. 2003; 83(1):187-230

6. Blume PA, Moore JC, Novicki DC. Digital mucoid cyst excision by using the bilobed flap technique and arthroplastic resection. J Foot Ankle Surg. 2005; 44(1):44-8.

7. Jager T, Vogels J, Dautel G. The Zitelli design for bilobed flap applied on skin defects after digital mucous cyst excision. A review of 9 cases. Tech Hand Up Extrem Surg. 2012; 16(3):124-6.

8. Hirase, Yuichi. Practical Techniques In Flap Surgery. Springer, Tokyo, 2017.

9 Saba SC, Lee J, Pathy VV, Weber RV. Salvage of a thumb replant using a bilobed dorsal metacarpal artery island flap: case report and literature review. Hand. 2008; 3(4):366-371.