Joshua D. Auerbach and Kingsley R. Chin

Description

To harvest autologous fibula or rib bone graft for spinal reconstructive procedures while minimizing donor-site morbidity.

Key Principles

Although autologous fibula and rib strut grafts are not routinely used for spinal reconstructive surgeries, they remain excellent options for those procedures that require long strut grafts. Autologous graft harvesting from the fibula or rib carries minimal added infection risk, achieves favorable rates of fusion, provides a source of vascularized cortical bone, and can be safely performed with minimal donor-site morbidity. Autologous fibular strut grafts have superior compressive strength compared with iliac crest and rib grafts.

Expectations

Safe harvest of autologous fibula or rib grafting for use in spinal reconstructive procedures.

Indications

Multilevel cervical corpectomies, posterior cervical reconstruction, posterior occipitocervical fusion, anterior thoracic spinal fusion and reconstruction for tuberculosis spondylitis, infection, neoplasm, and progressive kyphosis.

Contraindications

• Fibula: ankle pain, instability, lower extremity weakness, sensory or motor deficit, or lower extremity vascular compromise
  
• Rib: previous fracture and deformity

Special Considerations

In situations at high risk for delayed union or nonunion, such as multilevel fusions, thoracic/thoracolumbar kyphosis, or in tumor patients receiving perioperative radiation, vascularized fibular or rib grafts may be indicated to provide a solid initial biomechanical construct and facilitate a quicker time to fusion. If a vascularized fibular graft is considered, it is recommended to obtain preoperative arteriography to evaluate for anomalous vascularity or previous vascular injury of the fibular pedicle graft.

The fibula is a straight cortical bone that can provide a graft up to 26 cm in length. The vascular pedicle, which may be from 1 to 5 cm in length, is composed of the peroneal artery (1.5 to 2.5 mm in diameter) and its accompanying two vena comitantes (2 to 3 mm in diameter).

The rib is a curved, flexible bone that can provide a graft up to 30 cm in length. The shape of the graft can be modified by the choice of the rib and section of rib excised (from the flatter posterior portion to the curved anterior portion) to optimize contact between the graft and recipient bed. Its vascular pedicle, which may be from 3 to 5 cm in length, consists of the posterior intercostal artery (1.5 to 2 mm in diameter) and single intercostal vein (1.2 to 2.5 mm in diameter).

Special Instructions, Position, and Anesthesia

Fibula

The fibular graft site can be approached using either a posterior or lateral approach. The lateral approach is preferred, as it is simpler and quicker and can be done simultaneously with the majority of the indicated primary procedures. With the patient supine, a sandbag or roll is placed underneath the ipsilateral buttock for optimal visualization of the lateral leg. A tourniquet is applied to the thigh to maintain a bloodless field. General anesthetic is typically used, with or without supplementation with local long-acting anesthetic.

Rib

The patient can be placed in either the prone position if a posterior spinal procedure is anticipated, or in the lateral decubitus position with the graft side up, which allows for visualization of the rib along its entire course. In the lateral decubitus position, the ipsilateral arm is elevated anteriorly and cephalad away from the ribs and the table flexed at the midthoracic region to increase the intercostal space. The table is tilted anteriorly to allow the ipsilateral lung to fall anteriorly. A double-lumen tube is used to allow single lung ventilation. General anesthesia is typically used, with or without supplementation with local long-acting anesthetic.

• For posterior occipitocervical fusions in children, the rib is uniquely shaped to permit maximal graft-recipient bed contact. In children the rib is also an abundant source of graft material and rapidly regenerates, compared with iliac crest bone graft.
  
• Identify the intercostal neurovascular bundle running on the caudad surface of the rib before performing rib stripping to avoid intercostal neurovascular injury.

Difficulties Encountered

Obese patients may increase the difficulty of localizing the anatomy, especially the middle ribs. Have a low threshold to use fluoroscopy or plain radiographs to identify the correct rib. Excessive bleeding may occur after releasing the tourniquet, requiring reinflation and a vascular consult.

Key Procedural Steps

Fibular Harvest