Local Bone Graft

David N. Garras

Abstract

The use of bone graft in foot and ankle surgery is critical to the success of many of our everyday procedures. With the rising number of readily available allografts and biological augments, autograft use has decreased. However, autograft bone remains the gold standard in many fusions and nonunion repairs. In this chapter, we demonstrate technique for local autograft from the calcaneus, distal tibia, and proximal tibia.

Keywords: bone graft calcaneus, distal tibia, proximal tibia, nonunion, malunion

31.1 Indications

• Bone grafting is the general technique of placing new bone into spaces around a broken bone or an area where a bone defect is present. It is often used to fuse joints and fill gaps that have sustained bone tissue loss, or to repair other areas of the bone that have failed to heal properly.

• When bone graft is necessary, it can be either an autograft or an allograft. Autograft is bone taken from the patient’s healthy bone, while an allograft is donated bone that has been processed and frozen, typically from a cadaver. The autograft bone is the preferred option because there is less of a chance of cellular rejection, a greater number of viable cells, and a greater chance for proper adhesion (hatch). Autograft is osteogenic, osteoinductive, and osteoconductive.

• The surgeon has options in terms of where the autograft is harvested locally. Typically, cancellous bone harvest is taken from the proximal tibia, distal tibia, or the calcaneus. Alternative site—such as the iliac crest, femoral canal, distal femur—may be beneficial for large volumes or cortical bone grafts but are not considered local autograft. Local autografts provide usable osteoblasts, bone morphogenic proteins, and a scaffold to aid in a fusion, a malunion, or a nonunion of a fracture. In this chapter, we will cover the proximal tibia, distal tibia, and calcaneus cancellous autograft procedures.

• The three key principles of harvesting autograft bone are as follows:

31.2 Goals of Surgical Procedure

The goals of an autograft procedure are to safely harvest viable bone from the patient in order to use in an operation aimed to repair a bony defect, aid in an arthrodesis, or a nonunion. This is done with the aim of improving the patient’s quality of life and the rate of a successful procedure. Local bone harvesting procedures are simple, generally safe, and fairly well tolerated.

31.3 Advantages of Surgical Procedure

Autograft remains the gold standard for the treatment of nonunions and malunions, as well as to aid in arthrodeses. Autograft is preferred over allograft because of the lower rate of infection, lower revision rates, and a faster time to healing.¹ Proximal tibial autograft provides a higher number of viable cells and the largest amount of bone. However, it is typically associated with some postoperative pain. Distal tibial autograft may be used in hindfoot procedures where the calcaneus is involved and when proximal to the autograph is not an option such as with revision total knee arthroplasties. Calcaneal autograft is a readily available source of bone graft that can be used in a variety of midfoot and forefoot fusions or nonunion repairs and is very well tolerated.

31.4 Key Principles

Choosing the appropriate location for harvesting the autograft.

Meticulous dissection and soft-tissue protection to avoid any neurovascular or soft-tissue compromise.

Care not to weaken or fracture the harvest site.

• When deciding on the appropriate site to harvest the autograft, the surgeon must consider the volume of bone needed and possible future surgical procedures associated with the current procedure. For example, when performing a triple arthrodesis, it would be advisable to obtain bone graft from the proximal tibia because this gives you more graft for all three joints. This also avoids any defects within the distal tibia, given the need for ankle fusion or replacement in the future may be necessary.

31.5 Preoperative Preparation and Patient Positioning

31.5.1 Proximal Tibia

The patient is positioned supine. Anesthesia may be with a femoral and sciatic nerve block, a spinal, or general anesthetic. The leg is prepped and draped to above the knee.

31.5.2 Distal Tibia

The patient is positioned supine. Anesthesia may be with a popliteal and saphenous nerve block or a general anesthetic. The leg is prepped to the musculotendinous junction of the gastrocnemius muscle.

31.5.3 Calcaneus

The patient is positioned supine with a small bump under the ipsilateral hip. Anesthesia may be with a regional nerve block, an ankle block, or a general anesthetic. The leg is prepped to the musculotendinous junction of the gastrocnemius muscle.

31.6 Operative Technique

Local bone graft can be obtained by either creating a small cortical window using an osteotome or small saw in the metaphyseal bone and using a curette or gauge to obtain the graft or by using readily available bone harvesting equipment. When using an osteotome or saw created cortical window, care should be taken to avoid creating a stress riser in the bone where a fracture could potentially occur. The author’s personal preference is using a cylindrical trephine harvester, which avoids the risk of fracture propagation. Different diameter trephines are available for bone harvesting procedures.²

31.6.1 Proximal Tibia

Approximately 1 cm distal and 1 cm lateral to the insertion of the patellar tendon on the tibia, a 2-cm incision is made in the skin (Fig. 31.1). Blunt dissection is carried down to the anterior compartment fascia. The fascia is opened and an elevator is used to elevate the anterior compartment musculature off the lateral surface of the tibia. The trephine is then inserted directly on the bone. The position of the trephine should be checked fluoroscopically to ensure that the anterior and posterior cortices are not accidentally reamed. The trephine is then drilled into the proximal tibia in a radial clockwise direction. Multiple passes may be performed using the same entry hole by directing the trephine in different directions to obtain a larger quantity of graft. The trephine is then detached from the power equipment and a plunger is used to obtain the graft. Gelfoam is used to decrease bleeding from the cortical defect. The fascia is closed with interrupted Vicryl suture and the skin is closed in standard layered fashion.

31.6.2 Distal Tibia

An incision is made over the medial aspect of the distal tibia 2 cm above the ankle joint (Fig. 31.2). Care should be taken to avoid the saphenous nerve and vein. Blunt dissection is carried down to the bone. The periosteum is elevated off the medial tibia. The trephine is then inserted directly on the bone. The position of the trephine should be checked fluoroscopically to ensure that it is well above the ankle joint. The trephine is then drilled into the distal tibia in a radial clockwise direction. Multiple passes may be performed using the same entry hole by directing the trephine in different directions to obtain a larger quantity of graft. The trephine is then detached from the power equipment and a plunger is used to obtain the graft. Gelfoam is used to decrease bleeding from the cortical defect. The skin is closed in standard layered fashion.