Endoscopic vertical ramus osteotomy: a long-term prospective study

Abstract

The purpose of this prospective study was to evaluate the outcomes of endoscopic vertical ramus osteotomy (EVRO) with rigid fixation for the treatment of mandibular prognathism or asymmetry. Inclusion criteria were age >15 years, adequate clinical and radiographic documentation, and minimum postoperative follow-up of 3 years. Exclusion criteria were refusal to consent, rheumatoid arthritis, steroid use, and smoking. Demographic data, pre-operative (T0), immediate postoperative (T1), and latest follow-up (T2) clinical examinations and cephalometric analysis, procedure data, complications, and length of hospital stay (LOS) were documented. Ten fulfilled the inclusion criteria. Diagnoses included mandibular hyperplasia ( n = 5), stable condylar hyperplasia ( n = 4), and mandibular asymmetry secondary to condylar resorption ( n = 1). In total, 17 EVROs were performed. The mean operative time was 33 min per side. Mean mandibular setback was 4.7 mm. Mean LOS was 1.9 days. Latest follow-up ranged from 3 to 5 years. Skeletal stability was confirmed in nine patients. One patient exhibited recurrence of mandibular prognathism at 5 years due to late growth. No VII nerve deficits were encountered. Inferior alveolar nerve (IAN) paresthesia was noted in four patients, which resolved postoperatively. EVRO was fast and resulted in minimal blood loss, quick recovery, and skeletal stability.

The extraoral endoscopic vertical ramus osteotomy (EVRO) was first described in 2000 by Troulis et al. The first clinical results were described in a retrospective case series in 2004 and it was concluded that the procedure was feasible and the results acceptable. The purpose of the current prospective study was to document the early and long-term outcomes of the endoscopic approach for VRO with rigid fixation.

Patients and methods

A prospective non-randomized case-series study was designed and approved by the institutional review board and carried out in accordance with the Declaration of Helsinki. A sample of patients presenting to the Department of Oral and Maxillofacial Surgery from October 2004 through October 2007 for evaluation and treatment of mandibular prognathism were recruited.

Inclusion criteria were age >15 years, diagnosis of mandibular prognathism (hyperplasia) or any malocclusion requiring mandibular rotation or setback, and clinical and radiographic follow-up of at least 3 years. Exclusion criteria were refusal to sign the study consent form, rheumatoid arthritis, steroid use, smoking, and follow-up less than 3 years or inadequate documentation.

Preoperatively (T0), all patients underwent orthognathic diagnostic workup which included medical and dental history, clinical examination of the face and oral cavity, dental models, photographs, imaging studies with panoramic radiograph, lateral and antero-posterior cephalogram, cephalometric analysis, and computerized treatment planning (Dolphin Imaging & Management Solutions, Chatsworth, CA, USA).

The length of the operation by side, blood loss, complications encountered, and length of hospital stay (LOS) were documented. Blood loss was estimated by subtracting the amount of fluids used for irrigation from the whole amount of fluids in the suction bottles.

For the analysis of outcomes, patients were assessed immediately postoperatively (T1) and at the latest follow-up (≥3 years; T2) by clinical examination of facial symmetry and proportions, dental occlusion, overjet and overbite, maximal incisal opening (MIO), marginal mandibular nerve function, and inferior alveolar nerve (IAN) sensation. Inferior ALVEOLAR nerve examination included direction sensation, light touch, brush stroke, static two-point discrimination, Von Frey hairs, hot vs. cold, and dull vs. sharp. Photographs, lateral cephalograms, and panoramic radiographs were obtained immediately postoperative, at 6 months, 12 months, and annually thereafter.

Measurements performed for cephalometric analysis were overjet and overbite, SNB (sella–nasion–B point angle), lower face height (anterior nasal spine (ANS) to gnathion), and mandibular length (condylion to gnathion distance) preoperatively, immediately postoperatively, and at the latest follow-up.

Operative technique

The EVRO surgical technique carried out under general anaesthesia has been described previously. Briefly, through a 1.5-cm incision, 1 finger-breadth below the angle of the mandible, a subperiosteal dissection is completed to create an optical cavity and expose the mandibular ramus–condyle unit (RCU) ( Fig. 1 ). A specially designed, suction-assisted endoscopic elevator (Snowden-Pencer Inc., Tucker, GA, USA) and a 2.7-mm diameter, 30° Hopkins endoscope (Karl Storz Endoscopy-America, Inc., Culver City, CA, USA) were used for the procedures. The osteotomy was performed with a custom modified, long-shank reciprocating saw.

Fig. 1
(A) Schematic diagram demonstrating access to the ramus–condyle unit through a small submandibular incision below the angle of the mandible, and the insertion of the endoscope into the optical cavity. (B) Endoscopic view of the left ramus–condyle unit. The posterior border and the angle of the mandible are seen on the right side of the figure. A retractor has been inserted in the sigmoid notch (top of the figure). (C) Endoscopic view of the osteotomy, the setback, and rigid fixation. The proximal bony fragment is rigidly fixed to the distal fragment with three 2.0-mm diameter × 12–16mm length screws.
Source : Troulis M, Kaban L. Minimally invasive approach to the mandibular ramus–condyle unit. Tuttlingen, Germany: Endo-Press, 2007; with permission.

Results

Seventeen patients were enrolled in the study and underwent EVRO from October 2004 to October 2007. Seven patients were excluded because of inadequate follow-up (<3 years follow-up) and 10 patients remained in the study until completion. They included six females and four males of mean age 23.6 years (range 17–36 years) at the time of operation ( Table 1 ). Mean latest follow-up was 4.1 years, ranging from 3 to 5 years.

Table 1
Demographic, procedural data, diagnosis and complications.
Patient number Sex/age (years) Diagnosis Procedure Mandibular setback Duration of operation (per side) Blood loss (ml) Hospital stay (days) Complication
1 F/26 R condylar resorption and mandibular asymmetry
R crossbite/L open bite
L EVRO
R condylectomy and CCG
3 mm, rotation 40 min L 50 3 None
2 M/26 Mandibular prognathism EVRO bilaterally
Coronoidectomy bilaterally
10 mm 30 min R
30 min L
350 2 Bilateral inferior alveolar nerve paresthesia resolved by 6th postoperative month
3 M/17 Mandibular prognathism
Maxillary hypoplasia
EVRO bilaterally
LFI
Genioplasty
3 mm 31 min R
35 min L
170 1 Overgrowth
4 F/36 R condylar hyperplasia
Mandibular prognathism
Maxillary hypoplasia
R EVRO with high condylectomy
L SSO
LFI
Genioplasty
3 mm 42 min 250 2 None
5 M/18 Mandibular prognathism
Maxillary hypoplasia
EVRO bilaterally
LFI
6 mm 35 each side 200 2 R inferior alveolar nerve paresthesia resolved by 6th postoperative month
6 F/23 R rotational condylar hyperplasia
Mandibular prognathism
R EVRO with high condylectomy
L SSO
R inferior border ostectomy
4 mm, rotation 30 min 100 2 None
7 F/29 L condylar hyperplasia
Mandibular asymmetry
EVRO bilaterally
Genioplasty
4 mm,
genio advancement 4 mm
36 min R
32 min L
300 (50 from genioplasty) 3 None
8 F/20 Mandibular prognathism EVRO bilaterally 7 mm 42 min R
30 min L
300 1 R inferior alveolar nerve paresthesia resolved by 6th postoperative month
9 M/21 R condylar hyperplasia EVRO bilaterally
R high condylectomy
2 mm, rotation 37 min R
37 min L
200 1 L inferior alveolar nerve paresthesia resolved by 12th postoperative month
10 F/20 Mandibular prognathism EVRO bilaterally 5 mm 29 min R
33 min L
50 1 None
CCG, costochondral graft; EVRO, endoscopic vertical ramus osteotomy; F, female; L, left; LFI, Le Fort I osteotomy; M, male; R, right; SSO, sagittal split osteotomy.

Diagnoses included mandibular hyperplasia ( n = 5), stable condylar hyperplasia ( n = 4), and mandibular asymmetry secondary to unilateral condylar resorption ( n = 1). EVRO was performed for mandibular setback and/or mandibular rotation. Procedures performed included: bilateral EVRO alone ( n = 2); bilateral EVRO with high condylectomy on one side ( n = 1); bilateral EVRO with Le Fort I osteotomy ( n = 1); bilateral EVRO with Le Fort I osteotomy and genioplasty ( n = 1); bilateral EVRO with genioplasty ( n = 1); bilateral EVRO and coronoidectomies ( n = 1); unilateral EVRO with high condylectomy and sagittal split osteotomy (SSO) contralateral ( n = 2); unilateral EVRO and contralateral endoscopic condylectomy and costochondral graft (CCG) ( n = 1) ( Table 1 ).

In total, 17 osteotomies (EVRO) were performed. The mean operative time was 33 min per side, ranging from 29 to 42 min. This included 8 min for incision/exposure, 2 min for the osteotomy, and 23 min for fixation, hemostasis, and closure. The mean intraoperative blood loss was 197 ml, ranging from 50 to 350 ml. These measurements included blood loss from Le Fort I osteotomy (200 ml, n = 1), genioplasty (300 ml, n = 1), or both ( Table 1 ).

Maxillomandibular fixation (MMF) was used only intraoperatively and was released at the end of the procedure in all patients except the one who underwent contralateral condylectomy and reconstruction with CCG. Rigid fixation was achieved with three 2.0-mm diameter × 12–16-mm length screws through four cortexes of the proximal and distal mandibular segments. A trocar was necessary in two cases, otherwise screws were placed through the submandibular incision ( n = 15). For high condylectomy to be performed ( n = 3), the proximal segment was removed from the surgical site and the hyperplastic condylar region was excised with a reciprocating saw. The proximal segment was then replaced in a more superior position and rigidly fixed with 2.0-mm screws. The endoscope was maintained in the optical cavity throughout the procedure, and all surgical steps (osteotomy, bony segment positioning, and fixation) were performed under direct visualization in all patients. Preplanned occlusion was achieved in all patients. The mean setback of the mandible was 4.7 mm, ranging from 2 to 10 mm.

In the immediate postoperative period, there was minimal oedema, no infections, and no cases of marginal mandibular nerve weakness. IAN paresthesia was noted unilaterally in four patients and had resolved by the sixth postoperative month in three patients and at 1 year postoperatively in one patient. The LOS was 1 day for four patients, 2 days for four, and 3 days for two. The mean LOS was 1.9 days. Of the two patients who had 3 days LOS, one underwent condylectomy and CCG of the contralateral side to EVRO and her morbidity was associated with the donor site. The second patient was found with a low hematocrit postoperatively and had to be transfused with 2 units of red cells.

Mandibular motion and MIO were normal at 1 month postoperatively in all patients and remained normal, greater than 40 mm, at the latest follow-up. Lateral and postero-anterior cephalograms and panoramic radiographs performed immediately postoperatively and at follow-up visits confirmed the proper positioning of mandibular segments and condyles in the fossa.

Preoperative (T0), immediate postoperative (T1), and the latest follow-up (T2) cephalographic analyses are presented in Table 2 . Mean overjet was increased immediately postoperative from −2.7 to 1.98 mm and remained stable with no significant changes at the latest follow-up. Mean preoperative overbite was −0.39 mm ranging from −5 to 2 mm. There was an increase in overbite at T1 (mean 1.43 mm, range 0.1–2.9 mm) that remained stable at T2, with no statistically significant changes ( Fig. 2 ). Mean preoperative SNB was 87.08° (range 75.5–96.6°), mean postoperative SNB was 84.05° (range 78.7–90°), and at the latest follow-up was 84.34° ( Table 2 ). Long-term stability was confirmed in nine patients ( Figs. 2 and 3 ). One male patient, age 17 years at the time of the operation (case 3, Table 1 ), outgrew the correction at 5 years postoperatively. With the exception of this patient, the mean change of SNB between T1 (immediately postoperative) and T2 (latest follow up 3–5 years) was 0.25° (standard deviation 0.3°). The mean mandibular length (Co–Gn) decreased significantly immediately postoperatively (mean 125.34–120.2 mm) and remained stable with no significant changes at the latest follow-up ( Fig. 4 ). For the Co to Gn measurements, the two patients who also underwent genio advancement were excluded. Finally, the lower face height (LFH) decreased significantly from 75.51 to 72.83 mm immediately postoperatively and remained stable at the latest follow-up ( Fig. 5 ). The skin incision was not noticeable at 1 year postoperatively for all patients.

Jan 21, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Endoscopic vertical ramus osteotomy: a long-term prospective study
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