# Coronoidectomy > Coronoidectomy for BDS Oral Surgery — coronoid hyperplasia and false ankylosis, intraoral technique, bilateral release, interposition and physiotherapy. - Canonical URL: https://prepelephant.com/topics/bds/oral-surgery/coronoidectomy-bds - Exam / course: BDS · Subject: Oral Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Coronoidectomy", PrepElephant, https://prepelephant.com/topics/bds/oral-surgery/coronoidectomy-bds ## Direct answer Coronoidectomy excises the coronoid process of the mandible to release the temporalis muscle insertion and free mandibular opening in false ankylosis — restriction of mouth opening caused by obstacles outside the temporomandibular joint. The two leading indications are coronoid hyperplasia, a bilateral elongation of the coronoid processes in young men that slowly blocks opening, and fibrous extra-articular restriction from submucous fibrosis, burns or scarring; it is also performed alongside gap arthroplasty when true ankylosis coexists with a enlarged coronoid. Through an intraoral approach along the anterior ramus, the temporalis attachment is stripped, the coronoid is sectioned from the sigmoid notch to the anterior border and removed or down-fractured, and the raw area is covered with a temporalis flap or interposition material so the muscle does not reattach. The operation is wasted without aggressive, immediate, long-continued physiotherapy. ## What you must remember - **The diagnostic fork:** true ankylosis (intra-articular bony or fibrous fusion) versus false ankylosis (extra-articular obstruction); coronoid pathology, submucous fibrosis, scarring and muscle disease cause the false type — imaging plus the forced-opening (stretch) test under anaesthesia separate them. - **Coronoid hyperplasia profile:** painless, progressive limitation of opening in adolescent and young adult males, usually bilateral, with elongated coronoid processes on orthopantomogram or computed tomography and a normal condyle that translates normally on imaging. - **Stretch test logic:** under sedation, if forced passive opening succeeds, the restriction is muscular or fibrous; if the mandible will not be forced open, the joint itself is ankylosed — the test that decides whether coronoidectomy alone will work. - **Technique essentials:** intraoral incision along the external oblique ridge, subperiosteal stripping of temporalis from the anterior ramus, osteotomy from the sigmoid notch to the anterior border of the ramus, removal of the process (or pedicled down-fracture), with care for the buccal fat pad which often herniates into the wound. - **Bilateral reality:** in coronoid hyperplasia the restriction is usually bilateral even when asymmetrical; unilateral coronoidectomy commonly disappoints, and both sides may be staged or done together. - **Prevent reattachment:** cover the raw anterior ramus with temporalis muscle/fascia rotation or an interposition sheet, because the temporalis reattaching to the healing surface recreates the restriction. - **Physiotherapy is the operation's other half:** immediate, daily, sustained opening exercises (stacked tongue depressors, screw-type devices, rubber stops) for months; the expected prize is an interincisal gain to roughly 30-35 mm or more, lost rapidly if exercises stop. ## Working through a trismus case A 20-year-old man has watched his opening fall to 10 mm over five years — painless, no clicks, no history of chin trauma or ear infection. He chews paan with tobacco daily. Examination shows tight, blanched, fibrotic bands in both buccal mucosae; the orthopantomogram shows elongated coronoid processes with normal condyles; computed tomography confirms no ankylosis. Two diseases share this mouth: oral submucous fibrosis narrowing the soft corridor, and coronoid hyperplasia blocking the bony arc. Under general anaesthesia the stretch test confirms extra-articular restriction. Fibrotomy of the bands releases the soft tissue component; then each coronoid is stripped and sectioned through the intraoral approach, and if opening remains limited after one side, the contralateral coronoidectomy follows in the same sitting. Interincisal opening is measured before closure — the intraoperative number predicts the final result. The temporalis is sutured over the raw area, and physiotherapy begins within days with a scheduled device and daily measured increments, continued for at least six months. ## How the exam frames it Examiners test the fork first: "trismus in a young adult — how do you exclude ankylosis?" The winning answer runs through the history (childhood trauma, ear infection), imaging of the joint, and the forced-opening test under anaesthesia. The second favourite is the muscle question — which muscle inserts on the coronoid, and what is its full extent: temporalis, sweeping from the temporal fossa under the zygomatic arch to the coronoid tip and anterior ramus, which is why mere slicing of the tendon without excision or interposition fails as the muscle reattaches. Indian settings add the oral submucosis angle — submucous fibrosis is the commonest cause of progressive trismus in Indian practice, so a candidate who mentions fibrotomy, coronoid involvement in long-standing cases, and the paan-tobacco aetiology is answering the question the examiner is actually thinking of. The final mark-saver is stating that without postoperative physiotherapy the surgery is futile — reattachment and fibrosis reclaim the opening within months. ## Frequently asked questions ### What are the indications for coronoidectomy? Coronoid hyperplasia, false ankylosis from fibrosis or scarring, oral submucous fibrosis with coronoid enlargement, and as an adjunct to gap arthroplasty in true ankylosis. ### Which surgical approach is used? An intraoral incision along the external oblique ridge and anterior ramus, avoiding any external scar and allowing direct osteotomy from the sigmoid notch to the anterior border. ### What is the stretch test and why does it matter? Forced passive opening of the mandible under sedation; success indicates extra-articular (false) restriction where coronoidectomy helps, and failure indicates true joint ankylosis needing arthroplasty. ### Why is postoperative physiotherapy non-negotiable? The temporalis reattaches to the healing ramus and fibrosis contracts rapidly, so without immediate sustained exercises the gained opening is lost within months. ### Why is bilateral coronoidectomy often required? Coronoid hyperplasia is typically bilateral, and the elongated process on the unstated side continues to block the arc of opening after unilateral resection.