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Microsurgery

Introduction and background

Authors: Mette Hørberg, registrar in oral and maxillofacial surgery, Frederik Gulmark Hansen, med.stud., Magnus Balslev Avnstorp MD and Jytte Buhl, consultant in oral and maxillofacial surgery

Background

Craniomaxillofacial reconstruction poses inherent and unique challenges due to the three-dimensional configuration of the proposed construct and the critical importance to restore speech, swallowing, mastication and symmetrical facial contour. 

The first attempts in mandibular reconstruction used either allografts or reconstruction plates with a variety of pedicled tissue flaps, free fasciocutaneous flaps and free musculocutaneous flaps(1,2). The breakthrough in mandibular reconstruction came with the advancement of microvascular surgery to include composite free flaps, where free bone with or without a skin paddle offered reconstruction possibilities that permitted replacement of bone(3).

The fibula is a long, thin and lateral bone of the lower leg, running parallel to the tibia. It plays a significant role in stabilizing the ankle and supporting the muscles of the lower leg. The free-flap fibula graft was first described by Taylor and Miller in 1975(4) where the technique was developed to salvage two legs which would otherwise have been amputated and was the first successful distant transfer of a composite fibula graft by microvascular anastomoses to be reported by man. In 1989 Hidalgo(5) investigated fibula as a donor site for mandibular reconstruction, due to limitations using other donor sites, such as the scapula, radius and iliac crest(5). 

Figure 1 | V-Excision Free fibula flap used including muscle-cuff used for mandubular reconstruction

The advantages of the fibula included consistent anatomy, ample length, low donor site morbidity and the fact that it allowed a two-team approach due to the distance between the donor and receiver site(5).

The free fibula graft can be used for mandibular reconstruction, where osteotomies are required to provide a three-dimensional reconstruction and the skin paddle to replace the external skin, lip or intraoral lining such as the buccal mucosa or the floor of the mouth(6). 

The fibula is the longest bone that can be transferred by microsurgical techniques, with a length varying with the height of the patient. This transfer depends upon the endosteal and periosteal blood supply from the peroneal artery. 

Blood supply to long bones in general comes from three sources: nutrient artery system, metaphyseal-epiphyseal system and periosteal system. All bones possess larger or smaller foramina for the entrance of the nourishing blood-vessels, these are known as nutrient foramina, and are particularly large in the shafts of larger long bones, where they lead into a nutrient canal.  

The endosteal circulation is supplied through the nutrient artery system which is a high-pressure system that branches from the major systemic arteries and enter the cortex, usually accompanied by one or two veins, venae comitans through the nutrient foramen and enter the medullary canal. The nutrient artery system runs obliquely through the cortex and then branch into ascending and descending branches that again branch into arterioles and supply the inner 2/3 of mature bone via the haversion system. The main nutrient artery of the fibula is the peroneal artery, and it usually enters the middle third of the fibula. 

The peroneal artery gives off multiple branches to all of the surrounding muscles of the leg and to the lateral leg skin, in addition to the nutrient and periosteal vessels.

There are 2-6 cutaneous perforating branches of the peroneal artery, travelling along the posterior crural septum and through the soleus and flexor hallucis longus muscles, supplying a longitudinally oriented area of skin to be included with the harvested bone as an osteofaciocutaneous free fibula flap(6). The pedicle of the peroneal artery is usually about 6-8 cm(6) but varies with the length of the harvested bone and the orientation of the perforator. The pedicle vessels can then be anastomosed to a corresponding artery and vein in the neck.

Bony reconstruction of the craniomaxillofacial skeleton has become more accurate since the advent of virtual surgical planning. Virtual surgical planning (VSP) and computer aided design (CAD) / computer aided modelling (CAM)  offers significant benefits for use in complex oncologic osseous head and neck reconstruction by providing enhanced cooperation between surgical teams, the extirpative and reconstructive teams by synergistically planning the resection and reconstruction pre-operative, and the ability to customize models to patient’s individual characteristics, which offers potential for considerable intraoperative time saving.

Acknowledgements

Illustrations: Christian Kaare Paaskesen, med.stud.

References

  1. Brown JB et al. Silicone and Teflon prostheses, including full jaw substitution: laboratory and clinical studies of Etheron. Ann Surg. 1963;153:932-943.
  2. Chow JM et al. Primary mandibular reconstruction using the AO reconstruction plate. Laryngoscope. 1986;96:768-773.
  3. Neligan PC. Microsurgical Reconstruction of the Head and Neck. Quality Medical Publishing, Inc. 2010
  4. Taylor GI et al. The free vascularized bone graft. A clinical extension of microvascular techniques. Plast Reconstr Surg. 1975;55(5):533-44
  5. Hidalgo DA. Fibula free flap: a new method of mandible reconstruction. Plast Reconstr Surg. 1989;84:71–79.
  6. Booth PW et al. Maxillofacial Trauma and Esthetic Facial Reconstruction. Churchill Livingstone. Elsevier 2003.

Procedures

Procedures