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Can A Flexor Digitorum Brevis Muscle Flap Help Manage A Soft Tissue Defect After An Open Total Calcanectomy?
These authors discuss the use of the flexor digitorum brevis muscle flap for limb salvage in a patient with diabetes and osteomyelitis of the calcaneus.
Intrinsic muscle flaps have been an option for local soft tissue reconstruction since the 1970s. There has been an increased utilization of the muscle flap since that time for a variety of applications including coverage of foot defects. Of particular interest, surgeons have used the flexor digitorum brevis muscle flap commonly for salvage of the foot following an open total calcanectomy.
Osteomyelitis of the foot has become more prevalent due to the increased incidence of diabetes mellitus and peripheral vascular disease in patients.1 The incidence of osteomyelitis in the calcaneus is 7 to 8 percent of all cases of osteomyelitis.2 Chronic osteomyelitis usually occurs with open fractures, bacteremia or contiguous soft tissue infection. Gram-positive cocci account for a majority of calcaneal osteomyelitis.1,3
It is difficult to treat calcaneal osteomyelitis, particularly when the infection is associated with a significant ulceration. Tissue coverage can become an issue. The mainstay treatment of osteomyelitis is either long-term intravenous antibiotics or surgical debridement. Intravenous antibiotics may be successful in patients with acute osteomyelitis. However, when the infectious process becomes chronic or bone necrotic, antibiotics might not be sufficient.3
Surgical debridement is then the option. It is also the preferred option when it comes to patients who have renal disease. Certain antibiotics are known to be nephrotoxic and one should avoid these, especially in the face of end-stage renal disease. Surgical debridement consists of either a partial calcanectomy or total calcanectomy with or without flap coverage, or a more definitive procedure such as a below-knee amputation. Often, the amount of bone resection depends on the osseous integrity during surgery. Multiple surgical debridements may be required to eradicate the infection.
When a partial calcanectomy fails, one can perform a total calcanectomy to completely eradicate the infection of the calcaneus. A total calcanectomy is also warranted in cases in which a heel ulcer is greater than 50 percent of the heel pad.4 Authors have described a midline incision but with debridement-type amputations, it can be difficult to obtain closure.3
What You Should Know About The Flexor Digitorum Brevis Muscle Flap
The flexor digitorum brevis muscle flap is an option for plantar heel ulcerations and has been successful in the diabetic population.5 Surgeons have performed this procedure with other adjunctive procedures such as those for reconstruction of the Charcot foot.6 In this case report, we used the flexor digitorum brevis muscle following an open total calcanectomy for coverage of the talar articular surface.
The flexor digitorum brevis muscle is located in the first layer of plantar intrinsic musculature between the abductor hallucis and the abductor digiti minimi. It originates from the medial process of the calcaneus and plantar aponeurosis and inserts into the middle phalanx of the second through fifth toes.7 The muscle has a Type 2 vascular pattern with its vasculature based on the dominant arterial supply near the origin of the muscle. The mid-muscle belly gets supply from the medial plantar artery. The majority of the muscle blood supply is based on the lateral plantar artery.
The advantages of using a flexor digitorum brevis muscle flap include the close proximity to the defect, limited donor defect, the non-weightbearing surface of the heel, and limited functional disability since the flexor digitorum longus maintains flexion of the toes. The flexor digitorum brevis muscle is also easy to separate without affecting the vascularity of the foot if one does this cautiously. If the posterior tibial or dorsalis pedis vessels are damaged, transposition is contraindicated. Another advantage is that once the surgeon transfers the muscle flap, this muscle can provide a hospitable surface for a skin graft.5 Also, by providing a vascularized muscle, better antibiotic delivery can occur at the infected area.5
Some limitations of flexor digitorum brevis muscle flap use include extensive skin defects that involve the instep area as well as areas that are beyond the instep area. Since the flexor digitorum brevis muscle flap is limited in bulk and reach, it may not fill the entire defect. However, as long as one covers the bone, tendon or joint, it is adequate coverage to permit granulation and then delayed skin grafting can promote definitive coverage.5
The technique for performing a flexor digitorum brevis muscle flap is as follows. First make an incision on the plantar midline of the foot from the calcaneus to the metatarsal pad. Then dissect the plantar fascia from the muscle, sometimes leaving it in with the flap to augment its bulk. The division of the origin of the abductor hallucis muscle unroofs the tarsal tunnel and can simplify dissection. Identify, divide and transect the four flexor digitorum brevis tendons.
Perform retrograde dissection of the muscle off the quadratus plantae without severing the medial or lateral plantar arteries. Rotate the muscle to cover the defect. If more mobility is needed, one can divide the origin of the muscle, allowing for better coverage. If the posterior heel, lower Achilles tendon or medial/lateral malleoli need coverage, divide and elevate the lateral plantar artery in the mid-plantar aspect of the foot with the flap to achieve greater reach.8 It is very important to handle the muscle flap with caution as many complications can result from poor planning and damage from excessive tension. The dissection needs to be meticulous to avoid hematoma since this can lead to flap necrosis.5
A Closer Look At The Patient Presentation
A 56-year-old male presents with multiple comorbidities including type 2 diabetes, end-stage renal disease and hemodialysis, chronic osteomyelitis, peripheral arterial disease, coronary artery disease with a history of coronary artery bypass graft, a pacemaker, chronic atrial fibrillation and anemia. The patient had a non-healing ulcer to the right heel despite multiple osseous debridements, intravenous antibiotics and revascularization.
Revascularization included percutaneous angioplasty of popliteal and tibial vessels and then below the knee to a popliteal to dorsalis pedis bypass graft with the contralateral great saphenous vein. The calcaneus had a persistent infection with Enterobacter cloacae, vancomycin-resistant Enterococci and Pseudomonas.
Once the clinical signs of infection resolved, we performed an open total calcanectomy and subsequently used a flexor digitorum brevis muscle flap. We utilized negative pressure therapy for eight weeks and then covered the defect with a split thickness skin graft.
In Summary
The weightbearing area of the foot is notoriously difficult to heal, especially if there is bone, tendon or joint exposure. In this particular case, using the flexor digitorum brevis muscle flap assisted in limb salvage by filling a defect resulting from an open total calcanectomy and permitting rapid and durable granulation that allowed definitive closure skin grafting.
Dr. Vincenti is a Chief Resident at Cedars Sinai Medical Center in Los Angeles, Calif.
Dr. Belczyk is the Associate Medical Director at the Amputation Prevention Center at Sherman Oaks Hospital in Sherman Oaks, Calif.
References
1. Hatzenbuehler J, Pulling T. Diagnosis and management of osteomyelitis. Am Fam Physician. 2011; 84(9):1027-1033
2. Feigln RD, McAlister WH, San Joaqin VH, Middelkamp JN. Osteomyelitis of the calcaneus: report of eight cases. Am J Dis Child. 1970; 119(1):61-5.
3. Chen K, Balloch R. Management of calcaneal osteomyelitis. Clin Podiatr Med Surg. 2010; 27(3):417-429
4. Bragdon G, Baumhauer J. Total calcanectomy for the treatment of calcaneal osteomyelitis. Tech Foot Ankle Surg. 2008; 7(1):52-5.
5. Attinger CE, Ducic I, Cooper P, Zelen CM. The role of intrinsic muscle flaps of the foot for bone coverage in foot and ankle defects in diabetic and nondiabetic patients. Plast Reconstr Surg. 2002; 110(4):1047-1054.
6. Belczyk R, Ramanujam CL, Capobianco CM, Zgonis T. Combined midfoot arthrodesis, muscle flap coverage, and circular external fixation for the chronic ulcerated Charcot deformity. Foot Ankle Spec. 2010; 3(1):40-4.
7. Mathes ST, Nahai F. Clinical Atlas of Muscle and Musculocutaneous Flaps. Mosby, St. Louis, 1979, p. 279.
8. Hartrampf CR, Scheflan M, Bostwick J. The flexor digitorum brevis muscle island pedicle flap: a new dimension in heel reconstruction. Plast Reconstr Surg. 1980; 66(2):264-270
