Revisiting the Supraforaminal Horizontal Oblique Osteotomy of the Mandible

Evaluation of bone contact area and intercondylar distance changes in orthognathic surgery - a comparison between BSSO and HSSO technique depending on mandibular displacement extent

OBJECTIVES

The present study aims to assess the impact of bilateral and high oblique sagittal split osteotomy (BSSO/HSSO), as well as displacement distances and directions on the expected and achievable bone contact area (BCA) and changes in the intercondylar distance (ICD). The primary question addressed is whether mandibular splitting through BSSO results in a greater BCA and/or ICD when compared to splitting through HSSO.

MATERIALS AND METHODS

Totally 80 mandibular displacements were performed on 20 fresh cadavers, for each subject, four splints were produces to facilitate mandibular advancement as well as setbacks of 4 and 8 mm. Pre- and postoperative CBCT scans were performed to plan the surgical procedures and to analyze the expected and achieved BCA and ICD.

RESULTS

Regarding the maximum mandibular displacement, the expected BCA for HSSO/BSSO were 352.58 ± 96.55mm2 and 1164.00 ± 295.50mm2, respectively, after advancement and 349.11 ± 98.42mm2 and 1344.70 ± 287.23mm2, respectively, after setback. The achieved BCA for HSSO/BSSO were 229.37 ± 75.90mm2 and 391.38 ± 189.01mm2, respectively, after advancement and 278.03 ± 97.65mm2 and 413.52 ± 169.52 mm2, respectively after setback. The expected ICD for HSSO/BSSO were 4.51 ± 0.73 mm and 3.25 ± 1.17 mm after advancement and - 5.76 ± 1.07 mm and - 4.28 ± 1.58 mm after setback. The achieved ICD for HSSO/BSSO were 2.07 ± 2.9 mm and 1.7 ± 0.60 mm after advancement and - 2.57 ± 2.78 mm and - 1.28 ± 0.84 mm after setback. Significant differences between the BCA after HSSO and BSSO were at each displacement (p < 0.001), except for the achieved BCA after 8-mm setback and advancement (p ≥ 0.266). No significant differences were observed regarding ICD, except for the expected ICD after 8-mm setback and advancement (p ≤ 0.037).

CONCLUSIONS

Compared to the virtual planning, the predictability regarding BCA and ICD was limited. ICD showed smaller clinical changes, BCA decreased significantly in the BSSO group.

CLINICAL RELEVANCE

BCA and ICD might have been less important in choosing the suitable split technique. in orthognathic surgery.

Comparison of two surgical techniques (HOO vs. BSSO) for mandibular osteotomies in orthognathic surgery-a 10-year retrospective study

PURPOSE

To retrospectively compare the high-angled sagittal split osteotomy (HOO) and the bilateral sagittal split osteotomy (BSSO) for the correction of skeletal dysgnathias regarding intra- and postoperative complications.

METHODS

The electronic medical records of all patients treated with an orthognathic surgery at the Department for Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Frankfurt, Germany, between the years 2009 and 2019 were retrospectively reviewed.

RESULTS

Two hundred ninety-one patients were included. The overall complication rates were 19.78% (BSSO) compared to 12.5% (HOO) (p = 0.14). Significant differences were found regarding the operation time (HOO < BSSO, p = 0.02), material failure (HOO > BSSO, p = 0.04), and early recurrence requiring revision surgery (HOO < BSSO, p = 0.002). The use of a ramus plate significantly reduced the risk of plate failure (2.8% < 13.6%, p = 0.05). More bad splits (p = 0.08) and early sensory disorders (p = 0.07) occurred in the BSSO group.

CONCLUSION

The HOO presents a possible alternative to the BSSO since newly developed osteosynthesis material significantly reduces the risk of material failure. The BSSO is accompanied by higher risks of developing complications like a bad split and sensory disorders but, however, remains the standard for large anterior-posterior transpositions of the mandible.

Patient-specific 3D-printed cutting guides for high oblique sagittal osteotomy-an innovative surgical technique for nerve preservation in orthognathic surgery

Bilateral sagittal split osteotomy (BSSO) of the mandible according to Obwegeser/Dal Pont is considered to be gold standard in orthognathic surgery. Frequently reported complications of BSSO are injuries of the mandibular nerve resulting in paresthesia/anesthesia as well as inadequate mandibular bone fracturing ('bad split'). High oblique sagittal osteotomy (HOSO) was introduced to overcome these complications. We present an innovative HOSO modification using patient-specific 3D-printed cutting guides positioned on the outside of the ascending mandibular ramus and fixed in the incisura semilunaris, precisely marking the optimal height and angle of the osteotomy. Advantages are a decreased operation time due to the simplicity of this less invasive procedure, a potentially reduced frequency of mandibular nerve damage and bad splits as well as a lower bleeding risk.

Biomechanical assessment of different fixation methods in mandibular high sagittal oblique osteotomy using a three-dimensional finite element analysis model

With modern-day technical advances, high sagittal oblique osteotomy (HSOO) of the mandible was recently described as an alternative to bilateral sagittal split osteotomy for the correction of mandibular skeletal deformities. However, neither in vitro nor numerical biomechanical assessments have evaluated the performance of fixation methods in HSOO. The aim of this study was to compare the biomechanical characteristics and stress distribution in bone and osteosynthesis fixations when using different designs and placing configurations, in order to determine a favourable plating method. We established two finite element models of HSOO with advancement (T1) and set-back (T2) movements of the mandible. Six different configurations of fixation of the ramus, progressively loaded by a constant force, were assessed for each model. The von Mises stress distribution in fixations and in bone, and bony segment displacement, were analysed. The lowest mechanical stresses and minimal gradient of displacement between the proximal and distal bony segments were detected in the combined one-third anterior- and posterior-positioned double mini-plate T1 and T2 models. This suggests that the appropriate method to correct mandibular deformities in HSOO surgery is with use of double mini-plates positioned in the anterior one-third and posterior one-third between the bony segments of the ramus.

Revision of 116 orthognathic surgery patients operated on with the high-oblique sagittal osteotomy (HOSO): a retrospective case series (PROCESS-compliant article)

BACKGROUND

The high-oblique sagittal osteotomy (HOSO) is an alternative to a bilateral sagittal split osteotomy (BSSO). Due to its novelty, there are no long-term studies which have focused on describing the incidence and type of complications encountered in the post-operative follow-up. The aim of this retrospective study is to analyze patients operated on with this surgical technique and the post-operative complications encountered.

PATIENT AND METHODS

The electronic medical records of all patients treated with orthognathic surgery at the Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Frankfurt, Goethe University, Frankfurt, Germany, between the years 2009 and 2016 were retrospectively reviewed.

RESULTS

A total of 116 patients fulfilled the inclusion criteria. The cases operated on with the standard osteosynthesis (X, Y, and straight) showed a complication rate of 36.37% (n = 4/11). The cases operated on with the HOSO-dedicated plates (HOSO-DP) showed, in total, a complication rate of 6.67% (n = 7/105). The most common post-operative complication resulting from both fixation methods was a reduction in mouth opening and TMJ pain for 4.3%. During the first years of performing the surgery (2009-211), a variety of standard plates had material failure causing non-union or pseudarthrosis. No cases of material failure were observed in the cases operated on with the HOSO-DP. The statistical results showed a highly significant dependence of a reduction in OP-time over the years, when the HOSO was performed without additional procedures (R² > 0.83, P < 0.0015).

CONCLUSION

The rate of complications in the HOSO were shown to be comparable to the rate of complications from the BSSO reported in the literature. Moreover, the use of the ramus dedicated plate appears to provide enough stability to the bone segments, making the surgery safer.

CLINICAL RELEVANCE

The HOSO needs to be considered by surgeons as an alternative to BSSO. Once the use of the HOSO-DP was established, the rate of complications and the operation time reduced considerably.

Stress distribution is susceptible to the angle of the osteotomy in the high oblique sagittal osteotomy (HOSO): biomechanical evaluation using finite element analyses

AIM

This computational study aimed to evaluate the influence of the angle of the osteotomy when performing a high oblique sagittal osteotomy over the distribution of stress to the osteosynthesis plates and mandibular segments. Material and methods: For this purpose, a finite element analysis of different combinations was carried out based on the osteotomy angle and mandibular mobilization using Autodesk Inventor® resulting in a total of 72 simulations. To check the correlation between the osteotomy angles with respect to the tension in the mandibular structure in different mobilizations, a student t-test was used. Results: The results of the advancement mobilizations (2.5 mm to 5.5 mm) reported increasing values for tension in the probe of the fourth screw and in the probe of the plate surface as the osteotomy angle increased (p-value <10-8). The results of the setback mobilizations (-2.5 mm to -5.5 mm) show comparable values (p-value <10-8). The resulting contact surface between bone segments varies depending on the osteotomy angle, increasing 44.67% from 45° to 70° and decreasing 22.05% when the angle is reduced to 30°. Conclusion: The angle of the osteotomy is a very relevant parameter in the design of the studied mandibular osteotomy, since the distribution of the reported stresses is substantially susceptible to its variation.

CAD/CAM Engineered Patient-Specific Impants as a Reposition Device in Le Fort I and Modified Subcondylar Osteotomies: Case Report of Facial Deformity Correction in Acromegaly

Acromegaly is a medical condition where elevated growth hormone or insulin-like growth factor I levels cause several changes in the craniofacial soft and hard features. We report the correction of facial deformity and posterior open bite with Le Fort I and modified subcondylar osteotomies in a patient affected by acromegaly. Computer-aided design and manufacturing generated saw and drill guides were used to perform osteotomies and segment removal. The placement of the patient-specific implants (PSIs) was guided by predesigned drill holes ensuring the required and planned movement of the jaws and position of the PSIs. After segment removal, the PSIs fitted the predesigned drill holes with high precision and were secured without problems. The planned amount of mandibular and maxillary movement was achieved. The occlusion and osteotomies remained stable for the follow-up of 22 months. The use of PSIs combined with guided surgery can be beneficial for selected cases with asymmetry or posterior open bite enabling new approaches and yielding good functional and aesthetic outcome. The modification of conventional ramus osteotomy combined with utilization of ramus segment removal and the use of PSI for reposition is an interesting and promising technique for rare conditions with ramus height asymmetry.

Changes in the temporomandibular joint position depending on the sagittal osteotomy technique and extent of mandibular movement

The bilateral sagittal split osteotomy (BSSO) and high oblique sagittal split osteotomy (HSSO) are common techniques for mandibular movement in orthognathic surgery. The aim of this study was to evaluate the influence of both techniques, as well as movement distances and directions, on the position of the temporomandibular joint (TMJ). A total of 80 mandibular movements were performed on 20 fresh human cadaver heads, four on each head. Pre- and postoperative cone beam computed tomography was used to plan the surgical procedure and analyse the TMJ. Reference measurements included the anterior, superior, and posterior joint spaces, intercondylar distances and angles in the axial and coronal planes, and the sagittal, coronal, and axial angulations of the proximal segment. Only minor differences were found between the BSSO and HSSO techniques, particularly in terms of the intercondylar angle in the axial plane (P <  0.03) and the condylar angle of the proximal segment in the sagittal plane (P <  0.011). Observed changes in the TMJ were mostly opposite when moving the mandible forwards and backwards and increased with increasing movement distance. BSSO and HSSO result in similar changes in TMJ position. The extent of the movement distance influences the position of the condyle more than the osteotomy technique.

Application of Navigation Surgery in Temporomandibular Joint Ankylosis Case and Review of Literature

The aim of this article is to develop a navigation-guided oral and maxillofacial surgery including surgical planning, simulation and navigation in temporomandibular joint ankylosis case practiced in tertiary care hospital. After getting the computed tomographic angiography of head and neck, the special software of Brain lab^® is used to mark the arteries and veins of the patient, which was in close approximation to the mandibular condyle. Brain lab^® navigation system was used during the surgery to ascertain the middle meningeal artery location, and osteotomy cut was given. Navigation technology use in the neurosurgery is not new. But its use in the subcontinent in the field of maxillofacial surgery is quite rare. First time, it has been used scientifically in temporomandibular joint ankylosis case. Navigation technology use in the maxillofacial surgery requires a holistic imaginative/creative approach to make the surgeries more predictive and safe.

[Short osteotomy use in orthognathic surgery: benefit, disadvantage and perspective]

INTRODUCTION

 The short osteotomy was first reported by Blair in 1907 and was later described and characterized by Kater and Paulus in 2013. The technique involves an oblique supra-lingular osteotomy from internal to external, from top to bottom and from back to front. It is designed to divide the ramus into two segments, the joint and the mandibular body, and to ensure minimal valve equivalents. Both osseous valves were maintained in contact by obtaining surface contact proportional to the angle of the osteotomy.

MATERIALS AND METHODS

 We present a series of 82 patients to demonstrate the benefits of this technique in terms of stability and conservation of sensitivity.

RESULTS

 82 patients were included, of which 74 (90%) described normal sensitivity and 8 (10%) reported modified sensitivity two years post-surgery.

DISCUSSION

 On account of the nature and height of the short osteotomy cut, it is possible to avoid direct manipulation of the lower alveolar nerve. The postoperative sensitivity level is identical to the pre-operative level in more than 90% of cases. In good indications, this technique could be used preferentially to optimize postoperative nerve recovery. We also discuss the current limitations of this orthognathic surgery procedure, as well as the perspectives linked to the development of 3D printing and preoperative planning.

Modified Mandibular Sagittal Split Osteotomy

INTRODUCTION

Mandibular osteotomies aim to displace the dental arch to the necessary position, ideally without limitation, while preserving inferior alveolar nerve (IAN) function. Supraforaminal osteotomies offer nerve safety but limit the extent of advancement, whereas Epker and Obwegeser-Dal Pont osteotomies enable unchallenged mandibular advancement but are associated with an inferior border notch. Here, we describe a new technique to avoid such disadvantages.

TECHNICAL NOTE

The beginning of the procedure was similar to Epker's technique, with sectioning of the lingual cortex up to the level of the lingula. Sectioning of the buccal cortex was stopped 3 to 4 mm above the inferior border and then performed horizontally up to the gonial angle in total thickness. The inferior border periosteum and muscles attachments were conserved and hence, appropriately vascularized.

DISCUSSION

This technique offers 4 advantages: absence of the inferior border notch, lower risk of damage to the IAN than with Epker's technique, sufficiently large bony surface to obtain bone healing as in Epker's technique, and no limitation to setback movement in contrast to Obwegeser-Dal Pont's or the supraforaminal osteotomy techniques.

Moving the mandible in orthognathic surgery - A multicenter analysis

Orthognathic surgery has always been a classical focus of maxillofacial surgery. Since more than 100 years, various surgical techniques for mandibular repositioning have been developed and clinically tested. Since the establishment of plate and screw osteosynthesis, orthognathic surgery became more stable and safe. Nowadays, different surgical methods for mobilising the mandible are existing. This international multicenter analysis (n = 51 hospitals) is providing first evidence based data for the current use of different surgical methods. The dominating techniques were Obwegeser/dal Pont (61%) followed by Hunsuck/Epker (37%) and Perthes/Schlössmann (29%). The main osteosynthesis materials were plates (82%), bicortical screws (23.5%), or a combination of both (5.9%). 47% of all centers reported to use several surgical methods at the same time, depending on the anatomical problem and the surgeon's preference. This shows that different surgical methods seem to work as comparable, safe, and reliable procedures in everydays clinical practise. On this basis, further prospective studies could evaluate possible advantages for our patients.

Angled Osteotomy Design Aimed to Influence the Lingual Fracture Line in Bilateral Sagittal Split Osteotomy: A Human Cadaveric Study

PURPOSE

The traditional osteotomy design in the bilateral sagittal split osteotomy includes a horizontal lingual bone cut, a connecting sagittal bone cut, and a vertical buccal bone cut perpendicular to the inferior mandibular cortex. The buccal bone cut extends as an inferior border cut into the lingual cortex. This study investigated a modified osteotomy design including an angled oblique buccal bone cut that extended as a posteriorly aimed inferior border cut near the masseteric tuberosity.

MATERIALS AND METHODS

The authors implemented a randomized controlled study. The study sample was comprised of 28 cadaveric dentulous mandibles. The primary outcome variable was the pattern of lingual fracture induced using the conventional (n = 14) and modified (n = 14) osteotomy designs. The secondary outcome variables included the incidence of bad splits and the status of the inferior alveolar nerve (IAN). Descriptive and bivariate statistics were computed.

RESULTS

The angled osteotomy design resulted in a significantly larger number of the lingual fractures originating from the inferior border cut (odds ratio [OR] = 1.54; 95% confidence interval [CI], 1.27-1.86; P < .01), with a significantly more posterior relation of the fracture line to the mandibular canal (OR = 2.11; 95% CI, 1.22-3.63; P < .01) and foramen (OR = 1.99; 95% CI, 1.28-3.08; P < .01). No bad splits occurred with the angled design, whereas 3 bad splits occurred with the conventional design, although this difference was not statistically significant (OR = 1.11; 95% CI, 0.99-1.25; P = .07). IAN status was comparable between designs, although the nerve more frequently required manipulation from the proximal mandibular segment when the conventional design was used (OR = 1.21; 95% CI, 0.99-1.47; P = .06).

CONCLUSION

The results suggest that the angled osteotomy design promotes a more posterior lingual fracture originating from the inferior border cut and a trend was apparent that this also might decrease the incidence of bad splits and IAN entrapment. These results must be carefully extrapolated to the clinical setting, with future studies clarifying these findings.

Low to high oblique ramus piezoosteotomy: a pilot study

Two major drawbacks of classical bilateral sagittal split osteotomy (BSSO) are occasional inferior alveolar nerve damage and bad splits. In order to avoid these two well-known disadvantages and benefit from ultrasonic bone cutting, a low-to-high oblique piezoosteotomy (LHO) was developed from Schlössmann's 1922 high oblique osteotomy, clinically evaluated with a standard and a novel osteosynthesis system. Eighty-five patients were retrospectively evaluated, 23 with an LHO osteotomy with standard osteosynthesis, 33 LHO with a dedicated plate osteosynthesis and compared to 29 patients with BSSO and standard osteosyntheses. The mean mandibular advancement in the LHO standard osteosynthesis/LHO dedicated plate osteosynthesis/BSSO collectives was 4.7 ± 2.5/7.8 ± 7.1/4.1 ± 2.8 mm, the mean one year relapse 2.6 ± 0.8 (p = 0.58)/1.4 ± 1.4 (p = 0.28)/2.1 ± 1.4 mm; the mean mandibular setback was 6.9 ± 3.6/7.7 ± 4.1/8.1 ± 4.9 mm and the one year relapse 2.9 ± 2.9 (p = 0.16)/1.4 ± 1.0 (p = 0.38)/1.5 ± 1.9 mm; clockwise rotation of the mandible was 5.2 ± 3.2/6.3 ± 5.1/10.2 ± 6.9°, the one year relapse 2.7 ± 1.2 (p = 0.18)/2.1 ± 1.7 (p = 0.09)/11.4 ± 9.3°; counterclockwise rotation averaged 6.4 ± 3.2/6.5 ± 7.9/6.5 ± 6.1° with a mean one year relapse of 3.3 ± 0.6 (p = 0.37)/3.7 ± 1.9 (p = 0.21)/4.5 ± 6.2°. LHO had 3%, BSSO 5% three months postoperative inferior alveolar nerve deficit (p = 0.17). The operation time was significantly shorter when LHO and dedicated plates were used compared to BSSO. Two broken conventional plates occurred in LHO, which stimulated the development of the dedicated plates used, one in BSSO; four bad splits in BSSO and two in LHO. Reosteosyntheses were performed using the newly developed dedicated "orthognathics" plate. LHO was successfully performed, easier and faster than BSSO. Gonial angle modifications were possible due to the oblique cut. Postoperative stability appears sufficient for moderate repositioning with a lower incidence of bad split and inferior alveolar nerve irritation, moreover blood loss was reduced. Since 2 standard miniplate fractures occurred in LHO, the "orthognathics" osteosynthesis was developed, applied and no further osteosynthesis fractures were seen.

Surgical navigation in reconstruction

Navigational systems are paramount in solving today's traffic dilemmas, and have important applications in the human body. Current imaging must be diagnostic and is often dictated by the radiologist, but it is up to the surgeon to consider surgical procedures and to decide in which case surgical navigation (SN) has advantages. Knowledge of the surgical capabilities of SN is indispensable. The aims of this article are to support real-time image-guided SN, present routine and advanced cases with precise preoperative planning, and show the scientific capabilities of SN.