Piezoelectric tools are the novel ultrasonic methods for effective and safe osteoplasty or osteotomy in comparison with traditional soft and hard tissue approaches using rotating instruments due to lack of microvibrations, ease of control and use, and safer cutting, mainly in complex anatomic areas. Piezoelectric indicates favorable and valuable outcomes based on the immediate postoperative morbidities, even though long-term results have not been investigated. It could be indicated that the piezosurgery in rhinoplasty can be considered as a reliable and safe method and should be taken into account as a part of the surgeon’s repertoire for rhinoplasty.
Key points
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In piezosurgery, a frequency of 25 to 29 kHz cuts only mineralized tissue and frequencies greater than 50 kHz cut neurovascular tissue and other soft tissues.
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The philosophy of applying the ultrasonic surgical devices in rhinoplasty decreases postsurgical sequelae (ecchymosis, edema, pain).
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Complete degloving of the nasal bone is not necessary for piezoelectric rhinoplasty.
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Endonasal or external lateral osteotomy could be performed with piezosurgery.
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Cost and learning curves are the main disadvantages of piezosurgery.
Introduction
The title of ultrasound determines the mechanical vibrations in frequencies higher than the human upper audible limit, which is higher than 20 Khz. Piezosurgery is based on the piezoelectric effect, in which an electric polarization is generated against mechanical stress in certain crystals and ceramics.
Piezoelectric tools have been used in bone surgeries since the last 20 years. It is appropriate for all bony surgery; however, it is most beneficial for the restricted access and/or the bones adjacent to the delicate soft tissues (nerves, vessels, mucosa, skin, pleura, and dura). Initially, piezoelectric was used in oral and dental surgical processes such as third molar extraction, excision of cysts, the formation of an opening into the maxillary sinus, preparing implant sites, and lifting the periosteum. Consequently, piezoelectric was used in maxillofacial surgery with extension to mandibular sagittal split osteotomies, temporomandibular joint surgery, cranial bone harvesting, and maxillary LeFort I osteotomies. Piezoelectric is chiefly effective in craniofacial surgery, as it permits the surgeon to do extensive osteotomies without damage to the adjacent neurovascular structures and underlying dura. Accordingly, applications of the standard use of piezoelectric in many different fields of surgery such as otological surgery (chain replacement and stapedectomy and facial nerve decompression), orthopedic surgery (osteotomy and hardware removal), and rhinoplasty have been launched. Various piezoelectric working tips have been laid out for currently available indications. ,
Fundamental science
Ultrasonic transduction is the principle of ultrasonic bone cutting, which is afforded by piezoelectric ceramic contraction and expansion, and making microvibrations. Essentially, they are modified by the transmission of an electric current across given crystals and ceramics leading to the oscillations that are then amplified and conveyed to a vibrating insert. Through suction irrigation, bony tissue is emulsified and eliminated without mechanical or thermal damage to the adjacent tissue. Adjusting the ultrasonic frequency at a low level causes the metallic insert for oscillating the cutting hard tissues (cartilages, bones) while leaving remaining soft tissues untouched (nerves, vessels, mucous membranes). The insert’s tip shakes within a range of 60 to 200 μm, permitting a very accurate bone incision. A frequency of 25 to 29 kHz is used, as only mineralized tissue is cut by the micromovements formed at this frequency; neurovascular tissue and other soft tissues are cut at frequencies greater than 50 kHz.
Piezoelectric tools normally include the main power unit and a foot switch and handpiece that are linked to it. This includes a holder for the handpiece containing irrigation fluids creating a modifiable jet of 0 to 60 mL/min through a peristaltic pump. It eliminates debris from the cutting area and guarantees accurate cutting. It also keeps a blood-free operation area as a result of cavitation of the irrigation solution and provides better visibility mainly in complex anatomic areas. The cutting features of the piezosurgery tool need to be set in terms of the level of bone mineralization, the design of the used insert, the speed of movement over usage, and the pressure used on the handpiece. ,
Tissues’ biological reaction
A piezoelectric tool contains numerous advantages for preparing the periosteum, based on the reports of some studies. Subperiosteal preparation and bone cutting by the piezoelectric device is associated with a positive influence on bone metabolism, faster healing, and bone regeneration, in comparison to the results of the conventional periosteal elevator, diamond, or carbide drills. Oxygen molecules sent out over cutting have an ultrasonic vibration and antiseptic impact and stimulate cellular metabolism. By the precision in the osteotomy, it is allowed to preserve the normal bone architecture, a factor contributing to the acceleration of bone regeneration. This positive effect of piezoelectric on bone remodeling in patients with comorbidities or treated with chemotherapeutic agents, bisphosphonates, or other medications should be investigated.
Some investigators have also pointed out that bone extracted from osteotomies conducted with a piezo device included more osteocytes and more vital bone than bone attained with usual methods.
The perfusion in osseous vessels in the bloodless piezoelectric bone cutting field was investigated by Von See and colleagues. Local overheating, cavitation effects, the flow of the cooling fluid, or intravascular thrombosis caused by the use of piezoelectric tools were assumed as the possible justification for the bloodless osteotomy site. Damage to vascular cell walls and standing waves in the vessels following the use of ultrasound and platelets aggregation (thrombus organization) are other assumptions that could reduce or even cutoff microvascular perfusion completely and lead to local infarction with subsequent necrosis. As a result of these investigations, the cavitation effects that are the formation of sound-induced gas bubbles and cavities at the negative peak pressure of an ultrasonic wave would be the main reason for the relative absence of blood, and the other probable aforementioned mechanisms are unlikely to occur at ultrasonic osteotomy site. Furthermore, it was histologically shown that bony surfaces cut with piezoelectric are present by a lack of coagulation necrosis by preserving osteocytes. This property proves the potential of piezoelectric in performing osteotomy, maintaining the low risk of osteonecrosis as a result of the selective and micrometric cutting action.
Piezoelectric rhinoplasty
The philosophy of applying the ultrasonic surgical devices in rhinoplasty decreases the postsurgical sequence (ecchymosis, edema, pain), maximizes the precision, and increases overall patient comfort. Patient satisfaction is imperative in aesthetic processes, and the surgeon’s motivation to use new approaches is enhanced by patient satisfaction.
Osteotomy is one of the most procedure-sensitive phases in rhinoplasty surgery and sturdily influences the patient’s clinical outcome, based on not only surgical results but also the safety and lack of complications. As established in the literature, edema and ecchymosis are straightly relative to the degree of soft tissue injury and the mechanical trauma to the bony surface over the osteotomies and skeletonizing. Surgeons for diminishing these inconveniences sequel have examined various methods, instruments, and intra- and postoperative materials and methods. ,
In conventional rhinoplasty surgery, management of the lateral walls and the bony vault is mostly conducted by mechanical tools including saws, osteotomes, chisels, and rasps that are independent of their design and greatly vulnerable to distracting major blood vessels in the soft tissues surrounding the nasal bone. These tools were refined for minimizing damage to the adjacent soft tissues and maximizing accuracy, over the years. Nevertheless, a search for more accurate surgical tools was prompted by the sustained absence of accuracy and the related uncontrollable fracture lines. Afterward, for overcoming the restrictions of manual instruments, electric tools with reciprocating heads were established. Surgeons use a piezoelectric technique for the management of different steps of rhinoplasty such as the lateral and bony vault osteotomy, deepening of the radix/glabellar, anterior nasal spine resection, correction of bony asymmetries, septoplasty, and turbinoplasty. , , ,
The initial cadaver study reported on using a piezo scalpel in rhinoplasty was published by Robiony in 2007, who performed lateral osteotomies via a percutaneous method ( Fig. 1 ), and the advantages including a minimal periosteal detachment, minimal or lacking internal mucosal damage, and the rapid linear cut were considered. Followed by their previous study, further study was conducted by investigators for more investigation on this issue. Their studies indicated that piezosurgery is a simply managed tool, along with the significant decrease in postoperative edema, trauma, and ecchymosis confirming the strict association between minor surgical trauma and better hard and soft tissue performance over healing.
Another human cadaveric experiment was performed by Ghassemi and colleagues. They used the special tool tip as a periosteal elevator for creating a subperiosteal tunnel around the pyriform aperture along the planned osteotomy track. The piezo scalpel was put within this tunnel, and the osteotomy was carried out alongside the osteotomy path with digital control. They mentioned that the piezosurgical scalpel is highly effective, easy to handle, controllable, and nontraumatic substitute for known osteotomy methods and does not lead to any mucosa laceration. The osteotomy with piezotome is carried out accurately in the intended osteotomy track, not resulting in any comminuted properties. Although requiring probably a learning curve, it is a straightforward technique to learn.
Only a few reports exist on controlled investigations that compare the piezoelectric nasal bone cut with the traditional method. Tirelli and colleagues compared the conventional osteotome and piezosurgery in 22 candidates undergoing rhinoplasty through an external method for osteotomy. The surgeon conducted a 2-mm long incision 8 to 10 mm below and medially to the medial canthus, including the skin, the periosteum, and the underlying superficial muscular aponeurotic system tissues. A narrow, curved, and unguarded tip of the piezoelectric was put via the pilot incision up to the nasal bone. Before activating, the tip was manually pushed caudally and cranially into the incision to create minimal periosteal detachment, limited to the considered line of the lateral osteotomy without requiring a subperiosteal tunnel. Edema and ecchymosis existed in the primary postoperative periods, only in 2 patients (20%) from the piezosurgery group in comparison to 12 patients (83%) from the usual technique group. This is another evidence that has mentioned a lower rate of postoperative morbidities with the piezosurgery application.
This study showed the osteotomies conducted with the piezoelectric seemed to be further linear, accurate, and efficient compared with those carried out with the traditional osteotome, particularly in the subjects with a wide nasal dorsum and thicker nasal bones.
Koc and colleagues represented the outcomes of a trial comparing the clinical outcomes of the ultrasonic external osteotomies with usual internal osteotomies. The 2 groups were compared based on the duration of surgery, postoperative edema, perioperative bleeding, pain, ecchymosis, and patient satisfaction on the first and seventh postoperative days. The piezosurgery group indicated considerably more favorable outcomes based on edema, hemorrhage, and ecchymosis on the first day postoperatively. On the contrary, ecchymosis and edema were also better on the seventh postoperative day in the piezosurgery group. Hemorrhage was the same in both groups on the seventh postoperative day. In the piezosurgery group, not only less pain was experienced on the first postoperative day, but also these patients were more pleased with their outcomes on both the first and seventh postoperative days. Based on the results of the current work, it is implied that piezosurgery is probably a safe, promising, and effective technique for lateral osteotomy, a critical stage in rhinoplasty. The satisfaction and comfort of both surgeons and patients counteract the time interval essential for the learning curve.
Taskın and colleagues assessed postoperative ecchymosis and edema in their double-blinded prospective work in patients undergoing open rhinoplasty and endonasal lateral wall osteotomy with piezoelectric as opposed usual tools. The whole subperiosteal degloving of the whole nasal bone was performed up to the medial canthus, nasion, and nasal maxillary sulcus in all patients, not related to the kind of used osteotomy tool ( Fig. 2 ). On the second day, the edema scores were considerably incremented in comparison to the seventh day in both groups. Nevertheless, no considerable difference was found between groups. In postoperative day 2, the ecchymosis scores were slightly higher in comparison to that on day 7; in both groups, however, it was not significant statistically. In this work, it was indicated that the main reason for ecchymosis and edema observed after rhinoplasty is associated with the soft tissue injury. This is clarified by the whole subperiosteal degloving of the complete nasal bone leading to extreme soft tissue manipulation, essentially boosting the risk of edema irrespective of the conduction of the osteotomies with the traditional or ultrasonic method. However, despite the complete degloving of nasal bone by preventing soft tissue injury over osteotomy and diminishing the severity of ecchymosis, regardless of the used osteotomy tools, it should be expected to extend the recovery from edema. Other comparable investigations are required to assess the effectiveness of complete degloving of nasal bone in avoiding ecchymosis and edema. On the other hand, Fallahi and colleagues executed the double-blinded, randomized controlled trial for comparing the postoperative pain, ecchymosis, and edema in internal lateral osteotomies conducted using the piezosurgery tool with that using conventional technique. Surgeries started as a regular open rhinoplasty to perform a lateral osteotomy, submucosal tunnel with no complete nasal bone degloving made along the nasal surface of the maxilla’s ascending process in the same mode for both groups ( Fig. 3 ). Based on the results, doing internal lateral osteotomy via the piezosurgery tool is accompanied by the lower postoperative pain, ecchymosis, and edema in comparison to the usual osteotomy.
