- Email: [email protected]
Microvascular Free Bone Flap Harvest With Piezosurgery
J Oral Maxillofac Surg 69:1485-1492, 2011
Microvascular Free Bone Flap Harvest With Piezosurgery Pier Francesco Nocini, MD, DDS,* Matteo Turra, MD,† Stefano Valsecchi, MD,‡ Stella Blandamura, MD,§ and Alberto Bedogni, MD¶ The piezoelectric bone-cutting device was introduced in orthopedic surgery in the late 1980s as an alternative technique of bone cutting.1 Piezoelectric surgery has been developed to cut bone through ultrasonic microvibrations. The main characteristics of piezoelectric bone-cutting devices are the selective cut of mineralized structures without soft tissue damage, even in the case of accidental contact; a more precise cutting action than with mechanical instruments (ie, saw and bur) thanks to the micrometric vibrations; bloodless field due to the physical phenomenon of cavitation; and low intraoperative overheating of the device.2 The main limitation is represented by the operative time required for the osteotomy, longer than with traditional bone-cutting methods.3 The first use of Piezosurgery in oral and maxillofacial surgery was reported in 2000.4 Since then, it has been increasingly used in a variety of oral surgical procedures.5-7 Because the Piezosurgery device has proved to be a very effective and safe method of bone cutting, at present, its use is spreading in different surgical areas like maxillofacial surgery, otologic surgery, neurosurgery, orthopedics, and hand surgery.8 As regards the maxillofacial skeleton, Piezosurgery has proved to be a valuable tool in orthognathic surgery, orbital sur*Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. †Professor, Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. ‡Unit of Maxillofacial Surgery, S. Anna Hospital, Como, Italy. §Assistant Professor, Institute of Pathology, University of Padova, Padua, Italy. ¶Assistant Professor, Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. Address correspondence and reprint requests to Dr Bedogni: Section of Oral and Maxillofacial Surgery, Department of Biological and Morphological Sciences, University of Verona, Hospital G. B. Rossi, P. le LA Scuro, 10, 37134 Verona, Italy; e-mail: alberto. [email protected] © 2011 American Association of Oral and Maxillofacial Surgeons
0278-2391/11/6905-0050$36.00/0 doi:10.1016/j.joms.2009.10.016
gery, and rhinoplasty.9-11 We present and discuss the use of the piezoelectric bone-cutting device in microvascular free bone flap harvest and contouring for the reconstruction of jawbone defects.
Materials and Methods PATIENTS’ AND DEFECTS’ CHARACTERISTICS
Eleven consecutive patients underwent microsurgical reconstruction of the jaws between November 2008 and January 2009. Patient data are listed in Table 1. There were 9 females and 2 males, with a mean age of 59 years (range, 32 to 70 years). The mean size of the jawbone defects after surgical resection was 13.4 cm (range, 8 to 20 cm). Intraoral mucosal defects were present in 8 cases, with a mean size of 20.6 cm2 (Table 2). A cervical skin defect was present in 1 patient. Seven patients were reconstructed with an osseous fibula flap, 3 with an osteo-septo-cutaneous fibula flap, and 1 with a deep circumflex iliac artery flap (DCIA flap). PIEZOELECTRIC BONE CUTTING DEVICE
The Piezosurgery Medical II device (Mectron Medical Technology, Carasco, Genova, Italy) was used in all cases (Fig 1A). This device is certified for operating room use. It uses ultrasonic modulated frequencies that produce optimized micrometric vibrations between 60 and 200/s at 24 to 29 kHz; an output power of 22 W and an additional superposed frequency of 30 to 50 Hz for different bone qualities are accessible. The oscillation amplitude of the tool depends on the horizontal oscillation of 60 to 200 m and vertical oscillation of 20 to 60 m. Physiological sodium chloride solution at room temperature was used for cooling irrigation during the bone cuts. The Piezosurgery Medical II device was set to “bone” level 1, with “vibration” at 7 and “irrigation” at 4 to 5. Titanium inserts OT7-type and OT8 R/L-type were used (Fig 1B). A new insert was used for each operation.
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Table 1. PATIENT CHARACTERISTICS
Pt
Age
Gender
Disease
Affected Jaw
1 2 3 4 5 6 7 8 9 10 11
63 70 68 53 67 65 62 59 32 68 46
M F F F F F F M F F F
SCC IORN Chronic osteomyelitis BRONJ BRONJ Atrophy SCC BRONJ Ameloblastoma SCC IORN
Mandible Mandible Mandible Maxilla Mandible Mandible Mandible Mandible Mandible Mandible Mandible
Abbreviations: SCC, squamous cell carcinoma; BRONJ, bisphosphonate-related osteonecrosis of the jaw; IORN, infected osteoradionecrosis. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
SURGICAL TECHNIQUE
Fibula Flap The fibula flap was always harvested using a lateral approach to the anterior compartment of the leg. Proximal and distal osteotomies were done with a piezoelectric device 4 cm below and 4 cm above the fibular heads, respectively (Fig 2). Segmentation of the fibula was performed directly at the donor leg in all cases, to reduce the warm ischemia time. The number, shape, and orientation of each osteotomy were marked on the lateral aspect of the fibular shaft. Linear osteotomies and wedge ostectomies, according to the preoperative planning, were performed with the piezoelectric device and OT7-type inserts. The continuity of the periosteum was preserved and the vascular bundle was not dissected off nor protected during the osteotomy (Figs 3, 4).
DCIA Flap DCIA was harvested using the “retrograde dissection” approach described by Brown and included an internal oblique muscle component.12 Horizontal and vertical cuts of the iliac crest were made with the OT8- and the OT7-type titanium inserts, respectively. Neither dissection of the iliac muscle from the inner table of the iliac bone nor protection of the deep circumflex iliac pedicle was necessary during the horizontal osteotomy. Bone flap segmentation was performed with the OT7-type titanium insert on a side table, with the aid of a surgical resin template. Osteosynthesis of the bone segments was as follows: a single 2.0-mm locking reconstruction plate (large size) for mandibular basal bone defects reconstructed with the fibula flap; 2.0-mm (small and medium size) locking plates for alveolar bone reconstruction; and 2.4-mm locking reconstruction plate for mandible defects reconstructed with the DCIA flap. A minimum of 2 monocortical locking screws were inserted in each vascularized bone segment. Three bicortical locking screws were used to fix the construct to the remaining mandibular stumps, while 2 monocortical locking screws per plate were used for bone buttressing of the maxilla. HISTOLOGIC EXAMINATION
One specimen from each fibular bone shaft was harvested with the piezoelectric device and histologically evaluated. Every specimen was sliced to obtain bone sections of the cut surface consisting of the entire cross-sectional area of the fibula. The periosteal layer was always included. Specimens were fixed in 4% formaldehyde, decalcified, and embedded into paraffin blocks. Tissue blocks were cut into 5-m serial sections, stained with hematoxylin and eosin,
Table 2. DEFECT CHARACTERISTICS
Pt
Bone Defect (cm)
Skin Defect (cm2)
Oral Mucosa Defect (cm2)
Flap Type
Bone Segments
Osteotomic Lines
Bone Shaping Time (min)
1 2 3 4 5 6 7 8 9 10 11
8 10 18 12 15 9 12 20 9 12.5 13
0 30 0 0 0 0 0 0 0 0 0
20 0 15 0 9 0 36 20 12 48 5
DCIA Composite fibula Fibula Fibula Fibula Fibula Composite fibula Fibula Fibula Composite fibula Fibula
3 3 3 3 5 3 2 4 4 3 3
5 6 6 6 10 6 4 8 8 6 6
40 60 50 55 110 60 35 70 100 50 65
Abbreviations: DCIA, deep circumflex iliac artery; Pt, patient. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
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FIGURE 1. Mectron Piezosurgery Medical II system: A, Touch-screen platform with 2 piezoelectric hand pieces and individual peristaltic pumps. B, OT7 and OT8 cutting inserts. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
and photographed (Leica DMD 108; Leica Microsystems CMS GmbH, Wetzlar, Germany). STUDY VARIABLES
Outcome variables were the duration of bone shaping using the piezoelectric device, the free flap
survival rate, and the time necessary to bone consolidation. Outcome parameters were as follows: 1) the time required for completion of each osteotomy---for this purpose we considered a single-wedge ostectomy equivalent to 2 osteotomies in cut surfaces; 2) skin and mucosal healing of the recon-
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FIGURE 2. Fibula flap harvest with the Piezosurgery Medical II system: proximal osteotomy 4 cm below the fibular head; protection of the deep structures and pedicle is unnecessary. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
structed site; 3) radiographic signs of callus formation. OUTCOME DATA
Patients were followed up monthly for the first 3 months. At each visit, patients were examined to monitor soft tissue healing and photographs of the oral cavity were taken. Panorex were obtained at each follow-up, while a computed tomographic scan of the reconstructed jaw was performed at the 3-month follow-up.
Results BONE SHAPING
The mean number of osteotomies per patient was 6.5 (range, 4 to 10), while the mean number of bone segments per patient was 3.3 (range, 2 to 5). Because a single case of DCIA flap reconstruction of the jaws contributed to this series, the time required for its shaping was considered individually against the 10 cases of fibular bone shaping. The mean time for the proximal and distal osteotomy of the fibula was 4 and 5 minutes, respectively. The mean time for fibular bone segmentation in this
series was 65 minutes, while the mean time for a single fibula osteotomy was 10 minutes. Three OT7S-type titanium inserts broke during fibula bone shaping, twice in 1 single operation (patient 9). The inserts were immediately replaced without further waste of time. The handpiece had to be replaced in 1 case due to malfunctioning. The piezoelectric device had to be temporarily stopped in 2 cases due to overheating. CLINICAL FINDINGS
There were no postoperative major complications. Neither partial nor complete flap loss occurred. Patient 4 developed a salivary fistula because of the intraoperative injury of the parotid duct that required surgical repair under local anesthesia; hematoma and cervical wound dehiscence occurred in patient 3 that healed with local dressings. At 3 months, patient 8 presented with a fracture of the 2-mm locking plate. Luckily, the break occurred after bone union of the fibular bone segments was already established and there was no need for reoperative surgery. Partial necrosis of the full-thickness skin graft and subsequent delayed healing of the donor leg occurred in patient 7 after composite fibula flap harvest.
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FIGURE 3. Fibula flap shaping with the Piezosurgery Medical II system: wedge ostectomy with limited periosteal dissection of the lateral aspect of the fibular shaft and without any protection of the vascular bundle (white arrow). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
HISTOLOGIC FINDINGS
All fibular bone specimens showed normal bone structure with well-preserved bone marrow. No signs of necrosis due to thermal damage were observed (Fig 5). In addition, lamellar bone with viable osteocytes was evident in the cortical bone of the analyzed specimens, whereas living adipocytes were mixed with blood cells and vessels within the bone marrow (Fig 6). BONE HEALING
Panorex taken 2 months after surgery showed bone callus formation along the osteotomy lines in all cases, except for the DCIA flap where bone union became visible at 3 months of follow-up. Besides, 3-month postoperative computed tomographic scans confirmed complete bone union of the reconstructed jaws in all cases (Fig 7).
Discussion To the best of our knowledge, this is the first report on the use of a piezoelectric bone-cutting device in microvascular surgery.
Shaping of vascularized bone flaps is routinely performed with the help of oscillating saws or rotating instruments. The use of mechanical instruments speeds up the osteotomy process but it poses the risk of damaging the vascular bundle that runs along the bone surface. Most of the vascularized bone flaps used for jawbone reconstruction have a dominant periosteal blood supply. Preservation of the periosteum is therefore mandatory to ensure adequate blood supply to the bone segments.13 This is especially true for fibula flap reconstruction of jawbone defects, where multiple osteotomies are required to achieve the regular profile of the mandible or maxilla. When using mechanical instruments for fibular bone segmentation, the periosteum has to be stripped off all around the osteotomic site and the pedicle needs to be dissected and adequately protected with retractors. This maneuver is time-consuming and may jeopardize the circulation through the osteotomized bone, especially when 2-cm-small or even shorter bone segments are needed.14 Thanks to the selective cut of the piezoelectric device for mineralized structures, we were able to safely osteotomize the fibula without the need for any periosteal
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FIGURE 4. Four-segment double-barrel fibula flap shaped with Piezosurgery Medical II system: three 2 cm-long segments are visible with an intact periosteal covering (white arrows). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
and pedicle dissection. Because protection of soft tissues is unnecessary with piezoelectric device, handling and shaping of the bone flap with the pedicle still connected to the donor site is clearly eased. Considering the fibula flap only, the time needed for completion of a single osteotomy with the piezoelectric device is up to 10 times longer than with the oscillating saw. However, the time normally needed to dissect and protect both the periosteum and the pedicle at each osteotomic site when using traditional cutting methods is almost entirely saved. This makes the overall time necessary to complete fibula bone flap shaping with Piezosurgery Medical II device roughly equal to the traditional methods. The disparity in the shaping time among patients from this series partly depends on the number of osteotomies planned for each reconstruction, but also on the different bone flap quality. Iliac bone is largely made of bone marrow with thin cortical plates, while fibula is a strong bicortical bone. For these reasons, osteotomy of the iliac bone with Piezosurgery is faster than the fibula despite the wider cross-sectional area.
Bone density also may vary among individuals due to age, gender, and metabolic bone diseases like osteoporosis. Most patients from this series were 50-year-old females or even older with a reduced bone mass. This may have had a positive effect on the overall shaping time in those cases. Two titanium inserts broke during the fibula harvest in a young female patient, which might be linked to the thickness of the cortical bone plates rather than to the surgeon’s ability with the Piezosurgery Medical II device. The Piezosurgery Medical II device inserts used in this series have not been specifically designed for free bone flap harvest. In fact, they belonged to those commonly used for oral surgical procedures, which focus on the thinness of the insert to be effective. In the future, specifically designed inserts should be manufactured to be more resistant and have a wider cutting surface. The fact that bone healing of the vascularized bone segments was unaffected in this series is consistent with previous reports, which showed complete bone union after osteotomies of the jaws with the Piezo-
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FIGURE 5. Histologic features of the fibular bone surface after piezoelectric segmentation (H-E stain): the entire cross-sectional area of the fibular bone specimen shows living bone tissue without necrotic areas. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
FIGURE 6. Histologic features of the fibular bone surface after piezoelectric segmentation (H-E stain): same specimen (higher magnification) showing the preserved bone marrow architecture with living adipocytes (black arrowheads), blood cells, and vessels. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
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FIGURE 7. Three-months follow-up axial computed tomographic scan of a reconstructed maxilla: complete bone union of the fibula bone segments at their intersection (white arrows). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
surgery Medical II device.15 In addition, the time necessary for complete ossification of the bone segments does not differ from that normally required with traditional cutting methods.16 In conclusion, this preliminary experience showed that segmentation of vascularized bone flaps with Piezosurgery is a valuable alternative to conventional cutting methods for the following reasons: 1) it improves the intraoperative safety of the procedure, ensuring an adequate periosteal blood flow to the bone segments; 2) it does not increase the overall operative time; 3) it does not interfere with bone flap survival and bone healing.
References 1. Horton JE, Tarpley TM Jr, Jacoway J: Clinical applications of ultrasonic instruments in the surgical remove of the bone. Oral Surg Oral Med Oral Pathol 39:536, 1981 2. Vercellotti T: Technological characteristics and clinical indications of piezoelectric bone surgery. Minerva Stomatol 53:207, 2004 3. Schlee M: Ultraschallgestùzte Chirurgie-grundlagen und Mòglichkeiten. Zahnàrztl Implants 21:48, 2005 4. Vercellotti T: Piezoelectric surgery in implantology: A case report---a new piezoelectric ridge expansion technique. Int J Periodontics Restorative Dent 20:358, 2000 5. Vercellotti T, Podestà A: Orthodontic microsurgery: A new surgically guided technique for dental movement. Int J Periodontics Restorative Dent 27:325, 2007
6. Vercellotti T, De Paoli S, Nevins M: The piezoelectric bony window osteotomy and sinus membrane elevation: Introduction of a new technique for simplification of the sinus augmentation procedure. Int J Periodontics Restorative Dent 21:561, 2001 7. Sakkas N, Otten JE, Gutwald R, et al: Transposition of the mental nerve by piezosurgery followed by postoperative neurosensory control: A case report. Br J Oral Maxillofac Surg 46:270, 2008 8. Labanca M, Azzola F, Raffaele V, et al: Piezoelectric surgery: Twenty years of use. Br J Oral Maxillofac Surg 46:265, 2008 9. Landes AC, Stubinger S, Reiger J, et al: Critical evaluation of piezoelectric osteotomy in orthognathic surgery: Operative technique, blood loss, time requirement, nerve and vessel integrity. J Oral Maxillofac Surg 66:657, 2008 10. Gleizal A, Béra JC, Lavandier B, et al: Craniofacial approach for orbital tumors and ultrasonic bone cutting. J Fr Ophtalmol 30:882, 2007 11. Robiony M, Toro C, Costa F, et al: Piezosurgery: A new method for osteotomies in rhinoplasty. J Craniofac Surg 18:1098, 2007 12. Brown JS: Deep circumflex iliac artery free flap with internal oblique muscle as a new method of immediate reconstruction of maxillectomy defect. Head Neck 18:412, 1996 13. Collin T, Sugden P, Ahmed O, et al: Technical considerations of fibular osteocutaneous flap dissection. J Plast Reconstr Aesthet Surg 61:1503, 2008 14. Gur E, Chiodo A, Pang CY, et al: The vascularized pig fibula bone flap model: Effects of multiple segmental osteotomies on growth and viability. Plast Reconstr Surg 103:1436, 1999 15. Robiony M, Polini F, Costa F, et al: Ultrasonic bone cutting for surgically assisted rapid maxillary expansion (SARME) under local anaesthesia. Int J Oral Maxillofac Surg 36:267, 2007 16. Hidalgo DA: Fibula free flap: A new method of mandible reconstruction. Plast Reconstr Surg 84:71, 1989
Microvascular Free Bone Flap Harvest With Piezosurgery Pier Francesco Nocini, MD, DDS,* Matteo Turra, MD,† Stefano Valsecchi, MD,‡ Stella Blandamura, MD,§ and Alberto Bedogni, MD¶ The piezoelectric bone-cutting device was introduced in orthopedic surgery in the late 1980s as an alternative technique of bone cutting.1 Piezoelectric surgery has been developed to cut bone through ultrasonic microvibrations. The main characteristics of piezoelectric bone-cutting devices are the selective cut of mineralized structures without soft tissue damage, even in the case of accidental contact; a more precise cutting action than with mechanical instruments (ie, saw and bur) thanks to the micrometric vibrations; bloodless field due to the physical phenomenon of cavitation; and low intraoperative overheating of the device.2 The main limitation is represented by the operative time required for the osteotomy, longer than with traditional bone-cutting methods.3 The first use of Piezosurgery in oral and maxillofacial surgery was reported in 2000.4 Since then, it has been increasingly used in a variety of oral surgical procedures.5-7 Because the Piezosurgery device has proved to be a very effective and safe method of bone cutting, at present, its use is spreading in different surgical areas like maxillofacial surgery, otologic surgery, neurosurgery, orthopedics, and hand surgery.8 As regards the maxillofacial skeleton, Piezosurgery has proved to be a valuable tool in orthognathic surgery, orbital sur*Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. †Professor, Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. ‡Unit of Maxillofacial Surgery, S. Anna Hospital, Como, Italy. §Assistant Professor, Institute of Pathology, University of Padova, Padua, Italy. ¶Assistant Professor, Section of Oral and Maxillofacial Surgery, University of Verona, Verona, Italy. Address correspondence and reprint requests to Dr Bedogni: Section of Oral and Maxillofacial Surgery, Department of Biological and Morphological Sciences, University of Verona, Hospital G. B. Rossi, P. le LA Scuro, 10, 37134 Verona, Italy; e-mail: alberto. [email protected] © 2011 American Association of Oral and Maxillofacial Surgeons
0278-2391/11/6905-0050$36.00/0 doi:10.1016/j.joms.2009.10.016
gery, and rhinoplasty.9-11 We present and discuss the use of the piezoelectric bone-cutting device in microvascular free bone flap harvest and contouring for the reconstruction of jawbone defects.
Materials and Methods PATIENTS’ AND DEFECTS’ CHARACTERISTICS
Eleven consecutive patients underwent microsurgical reconstruction of the jaws between November 2008 and January 2009. Patient data are listed in Table 1. There were 9 females and 2 males, with a mean age of 59 years (range, 32 to 70 years). The mean size of the jawbone defects after surgical resection was 13.4 cm (range, 8 to 20 cm). Intraoral mucosal defects were present in 8 cases, with a mean size of 20.6 cm2 (Table 2). A cervical skin defect was present in 1 patient. Seven patients were reconstructed with an osseous fibula flap, 3 with an osteo-septo-cutaneous fibula flap, and 1 with a deep circumflex iliac artery flap (DCIA flap). PIEZOELECTRIC BONE CUTTING DEVICE
The Piezosurgery Medical II device (Mectron Medical Technology, Carasco, Genova, Italy) was used in all cases (Fig 1A). This device is certified for operating room use. It uses ultrasonic modulated frequencies that produce optimized micrometric vibrations between 60 and 200/s at 24 to 29 kHz; an output power of 22 W and an additional superposed frequency of 30 to 50 Hz for different bone qualities are accessible. The oscillation amplitude of the tool depends on the horizontal oscillation of 60 to 200 m and vertical oscillation of 20 to 60 m. Physiological sodium chloride solution at room temperature was used for cooling irrigation during the bone cuts. The Piezosurgery Medical II device was set to “bone” level 1, with “vibration” at 7 and “irrigation” at 4 to 5. Titanium inserts OT7-type and OT8 R/L-type were used (Fig 1B). A new insert was used for each operation.
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Table 1. PATIENT CHARACTERISTICS
Pt
Age
Gender
Disease
Affected Jaw
1 2 3 4 5 6 7 8 9 10 11
63 70 68 53 67 65 62 59 32 68 46
M F F F F F F M F F F
SCC IORN Chronic osteomyelitis BRONJ BRONJ Atrophy SCC BRONJ Ameloblastoma SCC IORN
Mandible Mandible Mandible Maxilla Mandible Mandible Mandible Mandible Mandible Mandible Mandible
Abbreviations: SCC, squamous cell carcinoma; BRONJ, bisphosphonate-related osteonecrosis of the jaw; IORN, infected osteoradionecrosis. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
SURGICAL TECHNIQUE
Fibula Flap The fibula flap was always harvested using a lateral approach to the anterior compartment of the leg. Proximal and distal osteotomies were done with a piezoelectric device 4 cm below and 4 cm above the fibular heads, respectively (Fig 2). Segmentation of the fibula was performed directly at the donor leg in all cases, to reduce the warm ischemia time. The number, shape, and orientation of each osteotomy were marked on the lateral aspect of the fibular shaft. Linear osteotomies and wedge ostectomies, according to the preoperative planning, were performed with the piezoelectric device and OT7-type inserts. The continuity of the periosteum was preserved and the vascular bundle was not dissected off nor protected during the osteotomy (Figs 3, 4).
DCIA Flap DCIA was harvested using the “retrograde dissection” approach described by Brown and included an internal oblique muscle component.12 Horizontal and vertical cuts of the iliac crest were made with the OT8- and the OT7-type titanium inserts, respectively. Neither dissection of the iliac muscle from the inner table of the iliac bone nor protection of the deep circumflex iliac pedicle was necessary during the horizontal osteotomy. Bone flap segmentation was performed with the OT7-type titanium insert on a side table, with the aid of a surgical resin template. Osteosynthesis of the bone segments was as follows: a single 2.0-mm locking reconstruction plate (large size) for mandibular basal bone defects reconstructed with the fibula flap; 2.0-mm (small and medium size) locking plates for alveolar bone reconstruction; and 2.4-mm locking reconstruction plate for mandible defects reconstructed with the DCIA flap. A minimum of 2 monocortical locking screws were inserted in each vascularized bone segment. Three bicortical locking screws were used to fix the construct to the remaining mandibular stumps, while 2 monocortical locking screws per plate were used for bone buttressing of the maxilla. HISTOLOGIC EXAMINATION
One specimen from each fibular bone shaft was harvested with the piezoelectric device and histologically evaluated. Every specimen was sliced to obtain bone sections of the cut surface consisting of the entire cross-sectional area of the fibula. The periosteal layer was always included. Specimens were fixed in 4% formaldehyde, decalcified, and embedded into paraffin blocks. Tissue blocks were cut into 5-m serial sections, stained with hematoxylin and eosin,
Table 2. DEFECT CHARACTERISTICS
Pt
Bone Defect (cm)
Skin Defect (cm2)
Oral Mucosa Defect (cm2)
Flap Type
Bone Segments
Osteotomic Lines
Bone Shaping Time (min)
1 2 3 4 5 6 7 8 9 10 11
8 10 18 12 15 9 12 20 9 12.5 13
0 30 0 0 0 0 0 0 0 0 0
20 0 15 0 9 0 36 20 12 48 5
DCIA Composite fibula Fibula Fibula Fibula Fibula Composite fibula Fibula Fibula Composite fibula Fibula
3 3 3 3 5 3 2 4 4 3 3
5 6 6 6 10 6 4 8 8 6 6
40 60 50 55 110 60 35 70 100 50 65
Abbreviations: DCIA, deep circumflex iliac artery; Pt, patient. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
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FIGURE 1. Mectron Piezosurgery Medical II system: A, Touch-screen platform with 2 piezoelectric hand pieces and individual peristaltic pumps. B, OT7 and OT8 cutting inserts. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
and photographed (Leica DMD 108; Leica Microsystems CMS GmbH, Wetzlar, Germany). STUDY VARIABLES
Outcome variables were the duration of bone shaping using the piezoelectric device, the free flap
survival rate, and the time necessary to bone consolidation. Outcome parameters were as follows: 1) the time required for completion of each osteotomy---for this purpose we considered a single-wedge ostectomy equivalent to 2 osteotomies in cut surfaces; 2) skin and mucosal healing of the recon-
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FIGURE 2. Fibula flap harvest with the Piezosurgery Medical II system: proximal osteotomy 4 cm below the fibular head; protection of the deep structures and pedicle is unnecessary. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
structed site; 3) radiographic signs of callus formation. OUTCOME DATA
Patients were followed up monthly for the first 3 months. At each visit, patients were examined to monitor soft tissue healing and photographs of the oral cavity were taken. Panorex were obtained at each follow-up, while a computed tomographic scan of the reconstructed jaw was performed at the 3-month follow-up.
Results BONE SHAPING
The mean number of osteotomies per patient was 6.5 (range, 4 to 10), while the mean number of bone segments per patient was 3.3 (range, 2 to 5). Because a single case of DCIA flap reconstruction of the jaws contributed to this series, the time required for its shaping was considered individually against the 10 cases of fibular bone shaping. The mean time for the proximal and distal osteotomy of the fibula was 4 and 5 minutes, respectively. The mean time for fibular bone segmentation in this
series was 65 minutes, while the mean time for a single fibula osteotomy was 10 minutes. Three OT7S-type titanium inserts broke during fibula bone shaping, twice in 1 single operation (patient 9). The inserts were immediately replaced without further waste of time. The handpiece had to be replaced in 1 case due to malfunctioning. The piezoelectric device had to be temporarily stopped in 2 cases due to overheating. CLINICAL FINDINGS
There were no postoperative major complications. Neither partial nor complete flap loss occurred. Patient 4 developed a salivary fistula because of the intraoperative injury of the parotid duct that required surgical repair under local anesthesia; hematoma and cervical wound dehiscence occurred in patient 3 that healed with local dressings. At 3 months, patient 8 presented with a fracture of the 2-mm locking plate. Luckily, the break occurred after bone union of the fibular bone segments was already established and there was no need for reoperative surgery. Partial necrosis of the full-thickness skin graft and subsequent delayed healing of the donor leg occurred in patient 7 after composite fibula flap harvest.
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FIGURE 3. Fibula flap shaping with the Piezosurgery Medical II system: wedge ostectomy with limited periosteal dissection of the lateral aspect of the fibular shaft and without any protection of the vascular bundle (white arrow). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
HISTOLOGIC FINDINGS
All fibular bone specimens showed normal bone structure with well-preserved bone marrow. No signs of necrosis due to thermal damage were observed (Fig 5). In addition, lamellar bone with viable osteocytes was evident in the cortical bone of the analyzed specimens, whereas living adipocytes were mixed with blood cells and vessels within the bone marrow (Fig 6). BONE HEALING
Panorex taken 2 months after surgery showed bone callus formation along the osteotomy lines in all cases, except for the DCIA flap where bone union became visible at 3 months of follow-up. Besides, 3-month postoperative computed tomographic scans confirmed complete bone union of the reconstructed jaws in all cases (Fig 7).
Discussion To the best of our knowledge, this is the first report on the use of a piezoelectric bone-cutting device in microvascular surgery.
Shaping of vascularized bone flaps is routinely performed with the help of oscillating saws or rotating instruments. The use of mechanical instruments speeds up the osteotomy process but it poses the risk of damaging the vascular bundle that runs along the bone surface. Most of the vascularized bone flaps used for jawbone reconstruction have a dominant periosteal blood supply. Preservation of the periosteum is therefore mandatory to ensure adequate blood supply to the bone segments.13 This is especially true for fibula flap reconstruction of jawbone defects, where multiple osteotomies are required to achieve the regular profile of the mandible or maxilla. When using mechanical instruments for fibular bone segmentation, the periosteum has to be stripped off all around the osteotomic site and the pedicle needs to be dissected and adequately protected with retractors. This maneuver is time-consuming and may jeopardize the circulation through the osteotomized bone, especially when 2-cm-small or even shorter bone segments are needed.14 Thanks to the selective cut of the piezoelectric device for mineralized structures, we were able to safely osteotomize the fibula without the need for any periosteal
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PIEZOSURGICAL FREE BONE FLAP SEGMENTATION
FIGURE 4. Four-segment double-barrel fibula flap shaped with Piezosurgery Medical II system: three 2 cm-long segments are visible with an intact periosteal covering (white arrows). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
and pedicle dissection. Because protection of soft tissues is unnecessary with piezoelectric device, handling and shaping of the bone flap with the pedicle still connected to the donor site is clearly eased. Considering the fibula flap only, the time needed for completion of a single osteotomy with the piezoelectric device is up to 10 times longer than with the oscillating saw. However, the time normally needed to dissect and protect both the periosteum and the pedicle at each osteotomic site when using traditional cutting methods is almost entirely saved. This makes the overall time necessary to complete fibula bone flap shaping with Piezosurgery Medical II device roughly equal to the traditional methods. The disparity in the shaping time among patients from this series partly depends on the number of osteotomies planned for each reconstruction, but also on the different bone flap quality. Iliac bone is largely made of bone marrow with thin cortical plates, while fibula is a strong bicortical bone. For these reasons, osteotomy of the iliac bone with Piezosurgery is faster than the fibula despite the wider cross-sectional area.
Bone density also may vary among individuals due to age, gender, and metabolic bone diseases like osteoporosis. Most patients from this series were 50-year-old females or even older with a reduced bone mass. This may have had a positive effect on the overall shaping time in those cases. Two titanium inserts broke during the fibula harvest in a young female patient, which might be linked to the thickness of the cortical bone plates rather than to the surgeon’s ability with the Piezosurgery Medical II device. The Piezosurgery Medical II device inserts used in this series have not been specifically designed for free bone flap harvest. In fact, they belonged to those commonly used for oral surgical procedures, which focus on the thinness of the insert to be effective. In the future, specifically designed inserts should be manufactured to be more resistant and have a wider cutting surface. The fact that bone healing of the vascularized bone segments was unaffected in this series is consistent with previous reports, which showed complete bone union after osteotomies of the jaws with the Piezo-
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FIGURE 5. Histologic features of the fibular bone surface after piezoelectric segmentation (H-E stain): the entire cross-sectional area of the fibular bone specimen shows living bone tissue without necrotic areas. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
FIGURE 6. Histologic features of the fibular bone surface after piezoelectric segmentation (H-E stain): same specimen (higher magnification) showing the preserved bone marrow architecture with living adipocytes (black arrowheads), blood cells, and vessels. Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
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PIEZOSURGICAL FREE BONE FLAP SEGMENTATION
FIGURE 7. Three-months follow-up axial computed tomographic scan of a reconstructed maxilla: complete bone union of the fibula bone segments at their intersection (white arrows). Nocini et al. Piezosurgical Free Bone Flap Segmentation. J Oral Maxillofac Surg 2011.
surgery Medical II device.15 In addition, the time necessary for complete ossification of the bone segments does not differ from that normally required with traditional cutting methods.16 In conclusion, this preliminary experience showed that segmentation of vascularized bone flaps with Piezosurgery is a valuable alternative to conventional cutting methods for the following reasons: 1) it improves the intraoperative safety of the procedure, ensuring an adequate periosteal blood flow to the bone segments; 2) it does not increase the overall operative time; 3) it does not interfere with bone flap survival and bone healing.
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