Tibial Reconstruction

Vishwanath R. Chegireddy

Michael J. A. Klebuc

Anthony Echo

DEFINITION

Trauma and neoplasia, requiring segmental bone resection, are the most common causes for segmental defects of the tibia.
Radiation-induced bone necrosis and infection, namely osteomyelitis, is also an indication for resection and possible reconstruction.
Reconstruction requires technical expertise, careful operative planning, and a detailed understanding of the problem at hand.
Large commitment by both the patient and the physician is paramount due to long complex rehabilitation period.
Options for reconstruction include either allograft or autograft material, most commonly a vascularized fibular graft.
Allografts were initially used but were associated with considerably high rates of complications and failures.
The concept of reconstruction of the tibial shaft with a vascularized fibular graft was first suggested by Chacha and colleagues in 1981.¹ They used the ipsilateral fibula as a vascularized pedicle graft for nonunion of the tibia.
It has since been shown to be a viable and reliable technique for tibial reconstruction.
The main advantage of using a vascularized autograft for tibial reconstruction is the ability to use the normal biology of bone healing for incorporation rather than relying on creeping substitution innate to prosthetic material/nonvascularized graft use.
The vascularized fibular graft undergoes hypertrophy overtime in response to continuous pressure load, which translates to remarkable long-term durability.²^,³^,⁴
Factors that make the fibula an optimal source for a vascular graft are as follows:
- Anatomic accessibility
- Independent blood supply
- Relatively dispensable in lower extremity function
- Capability to hypertrophy overtime in response to pressure

ANATOMY

The tibia is the second largest bone in the human body, after the femur.
Relevant leg anatomy includes four compartments (anterior, posterior, superficial, and deep posterior) (FIG 1).
The tibia is the stronger of the two bones in the lower leg. It is found on the medial side and is connected to the fibula by the interosseous membrane. It forms a type of fibrous joint called syndesmosis with very little movement.

FIG 1 • Cross-sectional anatomy of four compartments at the midtibial level.
The blood supply to the tibia is derived from a main nutrient artery and periosteal branches derived from the anterior tibial artery.
The fibula is a long and thin cortical bone with a small medullary component. In adults, the width of the fibula is 1.5 to 2 cm with a length of 35 cm of which approximately 25 cm of the fibular diaphysis can be harvested for free grafting.
Vascular supply to the diaphysis of the fibula is via a dominant nutrient endosteal artery and minor musculoperiosteal branches from the peroneal artery and veins. These vessels run parallel to the fibula and course between the flexor hallucis longus (FHL) and tibialis posterior muscle group.
The dominant nutrient artery branches 6 to 14 cm from the peroneal artery bifurcation and enters the fibula posterior to the interosseous membrane. It then courses into the nutrient foramen located in the middle third of the diaphysis and further divides into an ascending and descending branch.
Musculoperiosteal vessels are derived from the peroneal artery and travel within the posterolateral septum, through the flexor hallucis longus and tibialis posterior muscle, giving segmental rise to four to eight branches that supply the muscles in the anterior compartment, soleus muscle, and lateral leg skin territory. The majority of the periosteal branches are located in the middle third of the fibula.
Soft tissue defect coverage is achieved with a skin paddle supplied by perforators traversing through the posterior crural septum with the majority concentrating at the proximal and distal ends of the fibula. These fasciocutaneous perforators supply a skin paddle up to 10 × 20 cm in size.⁵

PATIENT HISTORY AND PHYSICAL FINDINGS

Detailed preoperative evaluation is required for patients undergoing extensive long bone resection and intercalary bone defect reconstruction.
Determination should first be made as to whether reconstruction or salvage is a viable option.
General health status should be carefully evaluated. An extensive reconstructive effort should not be undertaken on a patient with an overall poor health status.
The patient should have the ability to be compliant with both treatment and rehabilitation.
Pertinent history includes the presence of significant comorbidities such as deep venous thrombosis, peripheral vascular disease, lymphedema, trauma, venous insufficiency, diabetes, or social history such as smoking.
Special attention should be to consider cardiovascular, surgical, or hematologic diseases that may affect peripheral blood flow.
- Physical exam should include a lower extremity and vascular examination. This includes an evaluation of knee and ankle joints for range of motion and laxity and a foot Allen test with a Doppler probe to assess dorsalis pedis and posterior tibial arteries.
Peronea arteria magna is a congenital variant of the arterial inflow to the foot that affects about 1% to 8% of the population, where both the anterior and posterior tibial arteries are hypoplastic or absent with the peroneal artery serving as the single arterial supply below the knee. The artery may need to be reconstructed with a vein graft, or the other leg should be inspected.
Patients with an abnormal vascular exam or a history of trauma to the affected extremity will need additional preoperative imaging such as computed tomography angiogram (CTA), duplex ultrasound, or magnetic resonance angiography (MRA) to identify atherosclerotic occlusive disease or congenital anomalies.

IMAGING

Preoperative imaging of both the recipient and donor sites should include an evaluation of:
Recipient site:
- The extent of bone resection, length and diameter of the intercalary defect, and potential soft tissue defect (FIG 2). This allows the surgeon to determine the extent of the tumor burden, traumatic bone loss, or chronic osteomyelitis and plan for reconstructive options.
Donor site:
- Evaluate vascular supply with Doppler ultrasound (anterior tibial, posterior tibial, and dorsalis pedis arteries), and exclude any fibular deformities.
- Angiogram to look for vessel patency and flow to the foot

SURGICAL MANAGEMENT

Preoperative Planning

Determination must be made as to whether limb salvage is a viable option.
Taking into account patient factors and the extent of disease and/or resection is imperative in determining the need for tibial reconstruction vs amputation.
Assessment of defect must include the need for bone, muscle, and skin; all of which free fibular graft can provide.
Four centimeters of bone must be left proximally, whereas 6 cm must be left at the distal portions of the fibula for knee and ankle stabilization, respectively. Therefore, the maximum length of the graft obtainable will be the length of the donor tibia less 10 cm.
Donor site should be the contralateral leg if used as a free flap. This allows for simultaneous preparation of recipient site during fibula harvest and avoids the use of potentially injured/involved donor site where the fibula may have been fractured in the setting of trauma.