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Objective:
Avascular Necrosis (AVN) is a condition resulting from bone tissue death due to lack of blood supply. AVN most commonly occurs in the hip. There are 10,000 - 20,000 new cases of femoral AVN reported in the United States each year. The treatment of AVN using core decompression and adjuvant orthobiologic therapies have been shown to slow down disease progression; however, current surgical techniques may not accurately direct therapeutic devices to the necrotic locus. Furthermore, current means of performing this treatment may lead to multiple attempts at correcting guidance needle trajectory and thereby (1) increasing the risk of postoperative fracture and (2) compromising the healing process. We propose an image-guided minimally invasive method for delivering treatment to the optimal location in the femur.

Materials and Methods:
Patients underwent general anesthesia in preparation for this procedure. Autologous bone marrow was obtained from the anterior iliac crest and concentrated using a bone marrow processing system. Percutaneous pins were drilled into the lateral shaft of the femur to support an optical array for 3D navigation. An intraoperative CT scanner and a computer-assisted surgical navigation workstation were used to orient a universal drill guide. The drill guide was adjusted until the optimal drill trajectory for reaching the necrotic core is achieved. A guide wire was drilled according to the optimal drill trajectory through a percutaneous incision. Next, the outer cannula of a 230 mm long 8-gauge Jamshidi needle was advanced over the guide wire until it was positioned in the lesion. The cannula was used to deliver a core-decompression device with a flip-cutter to the diseased tissue. After performing decompression using the flip-cutter, adjuvant therapy consisting of 5 mL of demineralized bone matrix derived from human allograft, 1 mL of contrast dye (350 mgI/mL iohexol), and 2 mL of the bone marrow aspirate concentrate was administered to the osteonecrotic locus, via the cannula.

Results:
Nine patents were treated with core decompression and BMAC using the CT-based navigation approach. In eight of nine patients, the necrotic region was reached without reorienting the instrument. In one patient, a single reorientation attempt was required. The procedure took approximately 40 minutes to complete.

Conclusion:
This technique may be used to optimize the drilling trajectory and potentially improve the efficacy of decompression and adjuvant cellular therapy for patients with early-onset AVN. Moreover, it can allow better comparison between therapeutic strategies by standardizing treatment protocols.