Virtual Reality Techniques in Reconstructive Surgery

Dear Sir:

In reconstructive surgery, computer-assisted three-dimensional techniques are evolving rapidly. These techniques are increasingly used for the evaluation of anatomy and the creation of biomodels and implants. However, virtual reality techniques are still in an early phase of integration in daily practice. We present a case in which virtual reality techniques were used to plan and reconstruct a large maxillary defect with a free deep circumflex iliac artery composite graft.

A 62-year-old woman was sent to our department for the reconstruction of a large maxilla defect. She had been treated for a squamous cell carcinoma of the left maxillary sinus 8 months earlier. After radical hemimaxillectomy, the defect had been temporarily reconstructed with a prosthesis. The patient had significant wound-healing problems due to the adjuvant radiotherapy, which resulted in a persistent skin defect and exposure of the underlying prosthesis. In addition, she suffered from diplopia due to excision of the orbital floor. (Fig. [1])

Figure 1 Preoperative status. Note the asymmetrical position of the eyes, and the palatal defect intraorally.

Three-dimensional models of the maxillary defect and the crista iliaca donor site were made using CT-data (Mimics, Materialise, http://www.materialise.com). Using these models, a reconstruction of the defect was simulated in a virtual reality program (Free Form, SensAble, http://www.sensable.com). The desired outcome was established by mirroring the contralateral normal facial structure (Figs. [2], [3]). Subsequently, using a haptic device, virtual osteotomies were performed on the crista bone and the virtual graft was sculptured to match the defect[1] (Fig. [4]). A sterile version of the virtual bone graft and a surgical saw guide was made by stereolithography (Fig. [5]).

Figure 2 Osseous defect.

Figure 3 Desired osseous outcome.

Figure 4 Virtual reconstruction of DCIA-flap.

Figure 5 Sterile version of virtual bone graft and surgical guide.

After exposing the defect, the plastic crista model appeared to fit well. By using the surgical guide, the osteotomy lines were chosen. After detachment of the osteocutaneous free deep circumflex iliac artery composite graft, the graft was fixated to the surrounding bone with plate and screws. The vascular bundles of the graft were tunnelled to the mandible and microscopically anastomosed onto the submandibular facial artery and vein. The skin island of the graft covered the palatal defect and local mucosal flaps covered the remaining exposed bone.

The result was an improvement of the diplopia and a vital osseous covering of the maxillary defect, creating a bony base for an implant-retained denture. Also, the palatal defect was well covered by the skin island (Fig. [6]). Due to impaired wound healing as a result of radiotherapy, a second free flap was used to cover a facial defect.

Figure 6 Postoperative result.

In complex craniofacial operations, the use of biomodels in preoperative planning has many advantages.[2] [3] However, creating these models is expensive.[3] [4] By using virtual planning instead of biomodels, costs can be reduced. In addition, this virtual planning creates the possibility of performing unlimited virtual surgery and facilitates the exchange of information and evaluation with distant colleagues. This enhanced preparation can also result in a reduction of operative time. In this case, a biomodel was used in addition to the virtual preparation for validation purposes. However, with the increasing experience and confidence of the virtual reality preparation, the usage of biomodels may be totally abandoned in the future. With the ongoing development of hard- and software becoming more rapid, cheaper, and more accurate, virtual surgical planning is expected to play an increasingly important role in reconstructive surgery.

REFERENCES

• 1 Muenchenberg J, Woern H, Brief J et al.. Intuitive operation planning based on force feedback.  Stud Health Technol Inform. 2000;  70 220-226
• 2 D'Urso P, Atkinson R, Lanigan M et al.. Stereolithographic biomodelling in craniofacial surgery.  Br J Plast Surg. 1998;  51 522-530
• 3 Műuller A, Krishnan K, Uhl E. The application of rapid prototyping techniques in cranial reconstruction and preoperative planning in neurosurgery.  J Craniofacial Surg. 2003;  14 899-914
• 4 Rose E, Norris M, Rosen J. Application of high tech three dimensional imaging and computer generated models in complex facial reconstructions with vascularised bone grafts.  Plast Reconstr Surg. 1993;  91 252-264