What are the indications and considerations for using an instep foot flap in reconstructive surgery?

Indications and Considerations for Instep Foot Flap in Reconstructive Surgery

The instep foot flap is primarily indicated for reconstruction of weight-bearing plantar foot defects, particularly when local flaps are unavailable and the defect size does not require larger distant free flaps. 1

Primary Indications

• Reconstruction of moderate-sized defects of the weight-bearing heel and sole 1
• Plantar forefoot defect reconstruction when local flaps are unavailable 1
• Treatment of chronic plantar ulcerations, including those in patients with leprosy 2
• Heel defects requiring sensate coverage 3, 4

Anatomical Considerations

• The instep flap can be harvested as a fasciocutaneous island flap based on either the medial or lateral plantar neurovascular bundles, or both 3
• The flap provides similar tissue characteristics to the recipient site (like-with-like reconstruction) 1
• The flap can include sensory innervation through branches of the medial plantar nerve, making it suitable for sensate reconstruction 4
• No muscle is required in the flap, which provides greater stability for heel reconstruction and results in a lesser secondary defect 3

Clinical Applications

• Can be used as:
  • Pedicled island fasciocutaneous flap for local reconstruction 3
  • Free flap transferred from the contralateral foot when local options are unavailable 1, 3
• Particularly valuable for weight-bearing surface reconstruction due to similar tissue characteristics and potential for sensation 4
• Can reach the posteriormost part of the weight-bearing surface of the heel with ease 4

Surgical Planning Considerations

• Preoperative vascular imaging (CT angiography or MR angiography) is recommended to map the perforators and their branches, which can reduce operative time and increase flap reliability 5
• Understanding perforator anatomy helps in selecting the optimal perforator based on size, location, and intramuscular course 5
• The ideal perforator should be of large caliber and medially located within the flap 5

Advantages

• Provides similar tissue characteristics to the recipient site (like-with-like reconstruction) 1
• Can include sensory innervation for sensate reconstruction 4
• Absence of muscle provides greater stability for heel reconstruction 3
• Results in minimal secondary defect, particularly when no muscle is included 3
• Faster healing compared to conventional methods for chronic ulcers 2

Limitations and Considerations

• May not be available after severe foot injuries 1
• Sensation in the flaps may be diminished but generally adequate for long-term function 3
• Hyperkeratotic reaction remains an unpredictable problem 3
• Special footwear modifications may be required following reconstruction 2
• For large defects involving both sole and dorsum of the foot, compound flaps like the thoracodorsal perforator flap may be more appropriate 6

Alternative Options

• For large defects, free flaps from distant sites are generally preferred 1
• Compound (chimera) thoracodorsal artery perforator flaps can be considered for massive soft-tissue loss involving multiple functional units of the foot 6
• Both skin-grafted muscle flaps and fasciocutaneous flaps yield similar results, though reconstruction with like tissues appears favorable 1

The instep foot flap represents an excellent option for plantar foot reconstruction that balances functional outcomes with donor site morbidity, particularly when sensate coverage is desired for weight-bearing areas 1, 4.