J OralMaxillofacSurg 50:422-423,1992
An Intraoral Technique for Transoral Rigid Fixation of the Sagittal Split Ramus Osteotomy ANTHONY FAROLE, DMD*
Rigid screw fixation and immediate or early mobilization of the mandible is often desired by surgeons and patients. The advantages and possible disadvantages of rigid fixation of the sag&al split ramus osteotomy (SSRO) have been described by previous authors.“5 The two most popular techniques for drilling and placement of screws are 1) percutaneous placement through an incision in the cheek; and 2) transoral oblique placement. These methods use either pretapped or self-tapping screw placement, and either a positional or a lag technique in bicortical fixation. The disadvantage of the transoral method is the difficulty in placing the screw hole at right angles to the bone, with the risk of torquing the segments. We have been using a technique that uses a contraangle hardpiece for intraoral placement of screws for rigid fixation of the SSRO. This technique has been used in more than 70 cases during the past 3 years without complications.
of the proximal and distal segments if that is the surgical plan. Proper alignment is easily visualized with the use of a medium-sized toe-out retractor placed at the inferior border. A Stryker Command Electric System (Stryker Instruments, Kalamazoo, MI) with a latchtype contra-angle and a 1S-mm-diameter, 15mm long, twist drill is used transorally to place the first hole (Fig 1). This hole is drilled where there is maximum bone contact between the segments. This tends to prevent proximal or distal segment rotation. Drill speed is at 100% of power, which is less than 1,000 rpm, and coolant irrigation is used. The hole is placed perpendicular to the lateral border of the mandible through both proximal and distal segments. The surgical assistant uses a periosteal elevator or Freer elevator to retract the mucosa posterior to the second molar medially. This elevator “feels” the twist drill as it penetrates the distal segment and aids in determining screw length. After the hole is drilled, the screw is transferred by the surgical assistant to the desired area with the long Luhr screw holder. Next, a small Phillips screwdriver is placed into the contra-angle handpiece and at low speed (20% to 30% of full power), a Luhr Phillips-head
Technique After the SSRO is completed, the distal fragment is placed in the desired postoperative position with an indexing splint made preoperatively. Maxillomandibular fixation is applied with 25gauge stainless steel wire. A short high/low wire is placed and directed slightly posteriorly to seat the proximal segment and condyle gently and mostly vertically into the glenoid fossa. This also prevents counterclockwise rotation of the proximal segment and aligns the inferior borders
* Assistant Director, Division of Oral and Maxillofacial Surgery, Residency Program, Thomas Jefferson University Hospital; Associate Professor, Thomas Jefferson Medical College, Philadelphia, PA. Address correspondence and reprint requests to Dr Farole: 130 S 9th St, Suite 1120, Philadelphia, PA 19107. 0 1992 American
Association
of Oral and Maxillofacial
Surgeons
FIGURE 1. Perpendicular drilling through proximal and distal segments with 1%mm-long, 1.5-mm-diameter twist drill.
0278-2391/92/5004-0022$3.00/O
422
423
ANTHONY FAROLE
Discussion
FIGURE 2. Phillips-head screwdriver attachment inserting 2.0-mm Luhr screw at slow speed.
self-tapping screw is power driven into both segments (Fig 2). If additional screw tightening is required, which is seldom the case, a special hand-operated Luhr Contra-angle Screwdriver can be used. Commonly, a 14mm screw is used at the superior border in an averagesized mandible. Once the first screw is placed, the second and third are placed in the same manner. The screws are staggered, often in an inverted “L” pattern two above and one below the nerve, whenever possible.6 A fourth screw is seldom needed. The third screw is placed at the inferior border below the level of the inferior alveolar nerve. Most of the time there is sufficient distal segment bone beneath the nerve for this screw to be placed. It is always shorter than the superior border screws because the bone is thinner. Screw length in this area averages 10 to 12 mm. Observation of the course of the inferior alveolar nerve prior to segment wiring is important so that screws can be safely placed above or below the nerve, taking advantage of the best bone available. The versatility of the contra-angle handpiece allows easy access to virtually any area of the mandibular ramus or body area for screw placement. After both sides of the mandible are rigidly fixed, the maxillomandibular fixation is released and the occlusion is checked. Usually no elastic or wire fixation is used immediately postoperatively. However, often two or three class I, II, or III light elastics, as dictated by the direction of the surgical movement of the mandible, are placed later that evening.
There are no contraindications to the contra-angle technique except when rigid internal screw fixation is contraindicated. Important advantages of the technique include 1) transoral placement of screws; 2) perpendicular placement of screws, which probably improves accuracy of segment stabilization and prevents possible movement of the segments in a sag&al direction, leading to occlusa17 discrepancies; 3) very rapid and accurate placement of the screws, which are inserted at equal torque by selecting the same power settings on the control unit; this may guard against possible proximal and/or distal segment torquing’; and 4) the ability to place the screws into virtually any geometric pattern. Foley and others have shown that at least in an in vitro system, segment distortion and displaceability were less when a staggered, inverted-L pattern was used as opposed to when a linear, superior border technique was used.6 It is recommended that experience with this technique on a cadaver, dry skull, or facial bone alloplastic model be gained prior to using it clinically. As with the use of any new modification or technique, a learning curve exists. Accuracy, speed, and appreciation of subtle detail comes with time. Once the surgeon is comfortable, the contra-angle technique has definite advantages over other currently used methods for attaining rigid stabilization of the SSRO. References 1. Ellis E. Carlson DS: Stability of the mandible following advancement: A comparison of three postsurgical fixation techniques. Am J Orthod 94:38, 1988 2. Jeter TS. Van Sickels JE, Dolwick MF: Rigid internal fixation of ramus osteotomies. J Oral Maxillofac Surg 42:270, 1984 3. Proffit WR. Phillips C, Dunn C, et al: Stability after surgicalorthodontic correction of Class III malocclusion I. Mandibular setback. Int J Adult Orthod Orthognath Surg 6:7, I99 1 4. Spiessl B: Rigid internal fixation after sagittal split osteotomy of the ascending ramus, in Spiessl B (ed): New Concepts in Maxillofacial Bone Surgery. New York, NY, Springer-Verlag, 1976 5. Sowpis F: Sag&al splitting and bicortical screw fixation of the ascending ramus. J Maxillofac Surg 6:198, 1978 6. Foley WL, Frost DE, Paulin WB, et al: Internal screw fixation: Comparison of placement pattern and rigidity. J Oral Maxillofac Surg 47:720, 1989 7. Wolford L: Personal communication, February 1991 8. Amett GW, Tamborello JA, Rathbone JA: Temporomandibular joint ramifications of orthognathic surgery, in Bell WH (ed): Modem Practice in Orthognathic and Reconstructive Surgery. Philadelphia, PA, Saunders, 1990
An Intraoral Technique for Transoral Rigid Fixation of the Sagittal Split Ramus Osteotomy ANTHONY FAROLE, DMD*
Rigid screw fixation and immediate or early mobilization of the mandible is often desired by surgeons and patients. The advantages and possible disadvantages of rigid fixation of the sag&al split ramus osteotomy (SSRO) have been described by previous authors.“5 The two most popular techniques for drilling and placement of screws are 1) percutaneous placement through an incision in the cheek; and 2) transoral oblique placement. These methods use either pretapped or self-tapping screw placement, and either a positional or a lag technique in bicortical fixation. The disadvantage of the transoral method is the difficulty in placing the screw hole at right angles to the bone, with the risk of torquing the segments. We have been using a technique that uses a contraangle hardpiece for intraoral placement of screws for rigid fixation of the SSRO. This technique has been used in more than 70 cases during the past 3 years without complications.
of the proximal and distal segments if that is the surgical plan. Proper alignment is easily visualized with the use of a medium-sized toe-out retractor placed at the inferior border. A Stryker Command Electric System (Stryker Instruments, Kalamazoo, MI) with a latchtype contra-angle and a 1S-mm-diameter, 15mm long, twist drill is used transorally to place the first hole (Fig 1). This hole is drilled where there is maximum bone contact between the segments. This tends to prevent proximal or distal segment rotation. Drill speed is at 100% of power, which is less than 1,000 rpm, and coolant irrigation is used. The hole is placed perpendicular to the lateral border of the mandible through both proximal and distal segments. The surgical assistant uses a periosteal elevator or Freer elevator to retract the mucosa posterior to the second molar medially. This elevator “feels” the twist drill as it penetrates the distal segment and aids in determining screw length. After the hole is drilled, the screw is transferred by the surgical assistant to the desired area with the long Luhr screw holder. Next, a small Phillips screwdriver is placed into the contra-angle handpiece and at low speed (20% to 30% of full power), a Luhr Phillips-head
Technique After the SSRO is completed, the distal fragment is placed in the desired postoperative position with an indexing splint made preoperatively. Maxillomandibular fixation is applied with 25gauge stainless steel wire. A short high/low wire is placed and directed slightly posteriorly to seat the proximal segment and condyle gently and mostly vertically into the glenoid fossa. This also prevents counterclockwise rotation of the proximal segment and aligns the inferior borders
* Assistant Director, Division of Oral and Maxillofacial Surgery, Residency Program, Thomas Jefferson University Hospital; Associate Professor, Thomas Jefferson Medical College, Philadelphia, PA. Address correspondence and reprint requests to Dr Farole: 130 S 9th St, Suite 1120, Philadelphia, PA 19107. 0 1992 American
Association
of Oral and Maxillofacial
Surgeons
FIGURE 1. Perpendicular drilling through proximal and distal segments with 1%mm-long, 1.5-mm-diameter twist drill.
0278-2391/92/5004-0022$3.00/O
422
423
ANTHONY FAROLE
Discussion
FIGURE 2. Phillips-head screwdriver attachment inserting 2.0-mm Luhr screw at slow speed.
self-tapping screw is power driven into both segments (Fig 2). If additional screw tightening is required, which is seldom the case, a special hand-operated Luhr Contra-angle Screwdriver can be used. Commonly, a 14mm screw is used at the superior border in an averagesized mandible. Once the first screw is placed, the second and third are placed in the same manner. The screws are staggered, often in an inverted “L” pattern two above and one below the nerve, whenever possible.6 A fourth screw is seldom needed. The third screw is placed at the inferior border below the level of the inferior alveolar nerve. Most of the time there is sufficient distal segment bone beneath the nerve for this screw to be placed. It is always shorter than the superior border screws because the bone is thinner. Screw length in this area averages 10 to 12 mm. Observation of the course of the inferior alveolar nerve prior to segment wiring is important so that screws can be safely placed above or below the nerve, taking advantage of the best bone available. The versatility of the contra-angle handpiece allows easy access to virtually any area of the mandibular ramus or body area for screw placement. After both sides of the mandible are rigidly fixed, the maxillomandibular fixation is released and the occlusion is checked. Usually no elastic or wire fixation is used immediately postoperatively. However, often two or three class I, II, or III light elastics, as dictated by the direction of the surgical movement of the mandible, are placed later that evening.
There are no contraindications to the contra-angle technique except when rigid internal screw fixation is contraindicated. Important advantages of the technique include 1) transoral placement of screws; 2) perpendicular placement of screws, which probably improves accuracy of segment stabilization and prevents possible movement of the segments in a sag&al direction, leading to occlusa17 discrepancies; 3) very rapid and accurate placement of the screws, which are inserted at equal torque by selecting the same power settings on the control unit; this may guard against possible proximal and/or distal segment torquing’; and 4) the ability to place the screws into virtually any geometric pattern. Foley and others have shown that at least in an in vitro system, segment distortion and displaceability were less when a staggered, inverted-L pattern was used as opposed to when a linear, superior border technique was used.6 It is recommended that experience with this technique on a cadaver, dry skull, or facial bone alloplastic model be gained prior to using it clinically. As with the use of any new modification or technique, a learning curve exists. Accuracy, speed, and appreciation of subtle detail comes with time. Once the surgeon is comfortable, the contra-angle technique has definite advantages over other currently used methods for attaining rigid stabilization of the SSRO. References 1. Ellis E. Carlson DS: Stability of the mandible following advancement: A comparison of three postsurgical fixation techniques. Am J Orthod 94:38, 1988 2. Jeter TS. Van Sickels JE, Dolwick MF: Rigid internal fixation of ramus osteotomies. J Oral Maxillofac Surg 42:270, 1984 3. Proffit WR. Phillips C, Dunn C, et al: Stability after surgicalorthodontic correction of Class III malocclusion I. Mandibular setback. Int J Adult Orthod Orthognath Surg 6:7, I99 1 4. Spiessl B: Rigid internal fixation after sagittal split osteotomy of the ascending ramus, in Spiessl B (ed): New Concepts in Maxillofacial Bone Surgery. New York, NY, Springer-Verlag, 1976 5. Sowpis F: Sag&al splitting and bicortical screw fixation of the ascending ramus. J Maxillofac Surg 6:198, 1978 6. Foley WL, Frost DE, Paulin WB, et al: Internal screw fixation: Comparison of placement pattern and rigidity. J Oral Maxillofac Surg 47:720, 1989 7. Wolford L: Personal communication, February 1991 8. Amett GW, Tamborello JA, Rathbone JA: Temporomandibular joint ramifications of orthognathic surgery, in Bell WH (ed): Modem Practice in Orthognathic and Reconstructive Surgery. Philadelphia, PA, Saunders, 1990
