Flaps in reconstructive surgery

Oncology operations involve the removal of cancer from the head and neck region, commonly these patients require reconstruction to regain function and improve aesthetics. Therefore, one of the staples of OMFS is head and neck reconstructive surgery. Reconstruction involves harvesting a section of tissue to reconstruct a surgical defect and includes it's own blood supply. There are a number of different flaps, their selection based on the defect type. Before we discuss the different types of free flaps, let’s clarify some terminology:
1) Pedicled flap : the tissue to be transferred to the defect site is still partly attached to the donor site
2) Free flap : the tissue and it’s blood supply is completely detached from the donor site and transferred to the recipient site. This is referred to as anastomosis or "plumbing".
3) Graft : only the superficial layers of the skin are transferred, there is no involvement of the underlying blood supply [1].

Essentially, the aim of these operations is to resect the cancerous lesion with a margin of healthy tissue which will leave a defect. This defect will then be “filled in” using a flap. Additionally removal of lymph nodes in the neck aims to remove local metastasis or prevent further spread.

Neck Dissections

Most patients will have a neck dissection either for prophylactic use or due to regional spread. The metastatic potential for intra-oral cancers is relatively high. It is through the communicating lymph nodes of the head and neck that the cancer cells can spread. Therefore a neck dissection is the removal of the communicating lymphatic tissue. The presence of cancer cells in lymphatic tissue, extra-capsular spread and many other factors contribute significantly to prognosis.
“Metastasis to the regional lymph nodes reduces the 5-year survival rate by 50% compared with that of patients with early-stage disease. The American Cancer Society reports that 40% of patients with squamous carcinoma of the oral cavity and pharynx present with regional metastases.”
Before we discuss the procedure, it is important to understand the anatomy of the neck with regards to the levels of the neck, the location of vital structures and the general anatomy of the lymph node chain [2].

There are three main types of neck dissections:
1) Radical neck dissection: This involves the removal of lymph nodes from levels I-V together with the SCM, internal jugular vein and the spinal accessory nerve
2) Modified radial neck dissection: Removal of lymph nodes from levels I-V while aiming to preserve at least one of the other non-lymphatic structures (SCM, internal jugular vein and spinal accessory nerve)
3) Selective neck dissection: removal of selected lymph node levels. This is a more conservative procedure and is advantageous as it tries to preserve the spinal accessory nerve and the internal jugular vein.
Once the lymphatic tissue has been removed, it is then pinned and sent to the lab for pathologic staging. This can help to identify micr0-metastasis within further nodes which are sometimes undetectable on scans and examination and can also help to further inform the prognosis and required course of treatment [3].

Figure 1. Levels of the neck [4]

Radial forearm free flap (RFFF)

As the name suggests the origin of this flap is from the forearm. You will commonly see RFFF being used for reconstruction following total/hemi-glossectomy, floor of mouth defects and more posterior defects such as those following a laryngectomy/pharyngectomy (commonly seen in ENT). Note a RFFF does not harvest any bone however a modification to this flap (composite radial forearm free flap) aims to include part of the radial bone.
A split thickness skin graft is used to close the defect [5].

Fibula free flap (FFF)

Unlike the standard RFFF, this type of flap involves harvesting bone, soft tissue and a blood supply. For this reason, it is commonly used to reconstruct the mandible following a hemi-mandibulectomy or generally any type of resection which involves removing part of the mandible.
The fibula can be contoured to mimic the shape of the mandible. An advantage of a FFF is the bone can be used to hold dental implants at a later stage thus contributing to dental rehabilitation.

Antero-lateral thigh (ALT) flap

While this is not a bony flap, some consider it as the RFFF’s big brother. It is a fasciocutaneous flap primarily used to close large soft tissue defects. Therefore in some centres it is considered to be the flap of choice in total glossectomies. Also, one of its advantages is low donor site morbidity. In most circumstances, direct primary closure of the donor site can be achieved however if required, a split skin graft can also be used to aid closure [6].

Scapular free flap

This type of flap is commonly used to repair large volume defects involving bone. When harvested, it includes bone, muscles and skin. They are commonly used in patients who require maxillectomy’s and mandibulectomy’s. It offers a large pedicle and can be closed primarily most of the time provided the donor defect is less than 10cm. Note harvesting a scapular free flap is generally the most time consuming due to the inability of two teams to operate concurrently as the patient needs to be turned mid procedure[7].

Pectoralis major flap

Historically more popular, they still maintain an important role in head and neck reconstructive surgery. They are commonly used in salvage cases where the initial free flap has failed, or experienced a complication (e.g. dehiscence or osteoradionecrosis) or in patients who are predictably high risk candidates for a free flap. Note this type of flap is a pedicled flap [8].

Diagramatic representations of free flaps prior to detachment

Figure 2. Radial forearm free flap [9]
Figure 3. Fibula free flap [10]

References

[1] Gabrysz-Forget F, Tabet P, Rahal A, Bissada E, Christopoulos A, Ayad T. Free versus pedicled flaps for reconstruction of head and neck cancer defects: a systematic review. Journal of Otolaryngology - Head & Neck Surgery. 2019;48(1).
[2] Burusapat C, Jarungroongruangchai W, Charoenpitakchai M. Prognostic factors of cervical node status in head and neck squamous cell carcinoma. World J Surg Oncol. 2015 Feb 15;13:51]
[3] Gogna S, Kashyap S, Gupta N. Cancer, Neck Resection and Dissection [Internet]. Ncbi.nlm.nih.gov. 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536998/
[4] Cooper D, Doherty G, Haugen B, Kloos R, Lee S, Mandel S et al. Revised American Thyroid Association Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2009;19(11):1167-1214.
[5] Giordano L, Bondi S, Ferrario F, Fabiano B, Bussi M. Radial forearm free flap surgery: a modified skin-closure technique improving donor-site aesthetic appearance. Acta Otorhinolaryngol Ital. 2012;32(3):158‐163.
[6] George RK, Krishnamurthy A. Microsurgical free flaps: Controversies in maxillofacial reconstruction. Ann Maxillofac Surg. 2013;3(1):72‐79. doi:10.4103/2231-0746.110059
[7] Choi N, Cho JK, Jang JY, Cho JK, Cho YS, Baek CH. Scapular Tip Free Flap for Head and Neck Reconstruction. Clin Exp Otorhinolaryngol. 2015;8(4):422‐429. doi:10.3342/ceo.2015.8.4.422
[8] Liu, M., Liu, W., Yang, X. et al. Pectoralis Major Myocutaneous Flap for Head and Neck Defects in the Era of Free Flaps: Harvesting Technique and Indications. Sci Rep 7, 46256 (2017). https://doi.org/10.1038/srep46256
[9] Radial Forearm Flap [Internet]. Plastic Surgery Key. 2020. Available from: https://plasticsurgerykey.com/radial-forearm-flap/
[10] Themes U. Fibula Flap [Internet]. Plastic Surgery Key. 2020. Available from: https://plasticsurgerykey.com/fibula-flap-2/

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