Medial pterygoid muscle and stylomandibular ligament: the effects on postoperative stability
Clinical Paper
Orthognathic Surgery
Medial pterygoid muscle and stylomandibular ligament: the effects on postoperative stability
Clinical Paper
Orthognathic Surgery
Abstract
The postoperative skeletal stability following surgical advancement of the mandible can be influenced by several factors. The effect of the medial pterygoid muscle and the stylomandibular ligament on the stability of results following surgical advancement has possibly been underestimated. In this retrospective study, the long-term postoperative skeletal stability following surgical advancement of the mandible in two groups of patients was studied and compared. In one group the medial pterygoid muscle and the stylomandibular ligament were stripped from the medial side of the angle of the mandible during the bilateral sagittal split osteotomy (BSSO) procedure while for the other group of patients these muscles and ligaments were left attached. The long term skeletal stability of the two groups was compared and the group that had the muscles and the ligaments stripped proved to be more stable than the other group.
Section snippets
Materials and methods
50 patients (34 females and 16 males) requiring surgical advancement of the mandible for the correction of mandibular anteroposterior deficiency were included in the study. The average age of the patients was 25.3 years (15–47 years) at the time of surgery.
Group 1 included 25 patients (16 females and 9 males) with an average age of 23 years (15–43 years) at the time of surgery. In this group the medial pterygoid muscles and stylomandibular ligaments were left attached to the medial surface of
Measurement 1: mandibular length
The average increase in mandibular length for Group 1 was 5.95
mm (9.4
mm to 0.1
mm) while for Group 2 the mandibular length increased by 4.86
mm (9
mm to 1
mm) (Table 2). The difference in the increase was found to be significant (t test; p
=
0.083) between the two groups. The average relapse for Group 1 was 1.16
mm (−5.2
mm to +3.5
mm) and 0.26
mm (−2.5
mm to +1.8
mm) for Group 2 which was statistically significant (t test; p
=
0.034), but the greater forward movement in Group 1 was not taken into
Discussion
The results of the study suggest that long term skeletal stability following surgical advancement of the mandible by means of a BSSO is improved by stripping the medial pterygoid muscle and the stylomandibular ligament from the medial aspect of the mandibular angle during surgery.
When the SSO is performed according to the technique described by Trauner, Obwegeser and Dal Pont,1, 2 the posterior fracture line will involve the posterior and lower border of the mandible (Fig. 4). This pattern of
Funding
Own funding.
Conflict of interest
Nothing to declare.
Ethical approval
Ethical approval was obtained from the Human Research Ethics Committee (Medical). Clearance certificate: M091018.
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Cited by (19)
Long-term stability of mandibular advancement with bilateral sagittal split osteotomy
2018, Journal of Cranio-Maxillofacial Surgery
It has been hypothesized that stretching of the suprahyoid musculature and soft tissues could be the main cause of skeletal relapse after mandibular advancement surgery (Ellis and Carlson, 1983). Consequently, stripping of pterygoideus medialis muscle and stylomandibular ligament has been suggested to lower the risk of relapse (Joss and Thuer, 2008; Beukes et al., 2013). To reduce adverse the stretch and pull of muscles and soft tissues, distraction osteogenesis has been used instead of BSSO for mandibular advancement.
Effects of mandibular advancement surgery on the temporomandibular joint and muscular and articular adaptive changes—a systematic review
2016, International Journal of Oral and Maxillofacial Surgery
Yamada et al. observed that after advancement surgery in patients with TMD, flattening of the articular eminence may occur as a result of erosion, favouring the appearance of disc displacement without reduction.30 Valladares-Neto et al.2 and Beukes et al.5 concluded that young women with mandibular retrognathism and a higher mandibular plane angle are more susceptible to joint pain and show less improvement after advancement surgery. Nevertheless, a number of authors found an improvement in degenerative articular changes following this surgery.2,9,13,22,25
Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.