Bony Ankylosis Research Articles

IL-17A induces osteoblast differentiation by activating JAK2/STAT3 in ankylosing spondylitis

BackgroundIL-17A has recently emerged as a potential target that regulates the extensive inflammation and abnormal bone formation observed in ankylosing spondylitis (AS). Blocking IL-17A is expected to inhibit bony ankylosis. Here, we investigated the effects of anti IL-17A agents in AS.MethodsTNFα, IL-17A, and IL-12/23 p40 levels in serum and synovial fluid from patients with ankylosing spondylitis (AS), rheumatoid arthritis (RA), osteoarthritis (OA), or healthy controls (HC) were measured by ELISA. Bone tissue samples were obtained at surgery from the facet joints of ten patients with AS and ten control (Ct) patients with noninflammatory spinal disease. The functional relevance of IL-17A, biological blockades, Janus kinase 2 (JAK2), and non-receptor tyrosine kinase was assessed in vitro with primary bone-derived cells (BdCs) and serum from patients with AS.ResultsBasal levels of IL-17A and IL-12/23 p40 in body fluids were elevated in patients with AS. JAK2 was also highly expressed in bone tissue and primary BdCs from patients with AS. Furthermore, addition of exogenous IL-17A to primary Ct-BdCs promoted the osteogenic stimulus-induced increase in ALP activity and mineralization. Intriguingly, blocking IL-17A with serum from patients with AS attenuated ALP activity and mineralization in both Ct and AS-BdCs by inhibiting JAK2 phosphorylation and downregulating osteoblast-involved genes. Moreover, JAK2 inhibitors effectively reduced JAK2-driven ALP activity and JAK2-mediated events.ConclusionsOur findings indicate that IL-17A regulates osteoblast activity and differentiation via JAK2/STAT3 signaling. They shed light on AS pathogenesis and suggest new rational therapies for clinical AS ankylosis.

Temporomandibular Joint Ankylosis Release: 17Years of Experience with 521 Joints.

Various surgical techniques to release temporomandibular joint (TMJ) ankylosis have been described in the literature. The purpose of this paper is to report our Institution's experience regarding the post-surgical outcome of different surgical techniques for the release of ankylosis of the TMJ. The records from our hospital of 386 patients (521 joints) treated for TMJ ankylosis were reviewed. Data analysis included the etiology of TMJ ankylosis, gender distribution, age group, distribution of ankylosis based on location, type, interincisal opening and complications in the perioperative period. Out of 521 joints, 65.02% were unilateral and 73.89% had bony ankylosis. The mean maximal incisal opening preoperative was 5.4mm (SD 3.63mm) and at 1-year follow-up was 36.9mm (SD 3.3mm). There was no permanent facial nerve paralysis. However, transient facial nerve paresis was 14.78%. There was an overall recurrence rate of 8.82%. We conclude that after TMJ ankylosis release with interpositional arthroplasty, reconstruction of the RCU with L ramus osteotomy is the most favorable. This procedure not only causes least complications, but also maintains height of ramus, facilitating surgeries for secondary asymmetry correction.

A CLINICAL EFFECT OF AABHADI CHOORNA ON KATISHOOLA W.S.R. TO ASTHIMAJJAGAT VATA - A CASE STUDY

Katishoola is one of the vatavyadhi and it is the commonest disorder found in clinical practice. According to Ayurveda, Katishoola is the diseases with pain in lumber region. Katishoola can be equated with low back pain .The allopathic system of medicine use non-steroidal anti-inflammatory drugs, analgesics, which is not safe and effective for katishoola.
 A 60 year old male patient had suffering from progressive pain in lower back and difficulty in bending forward over 25 ˚ and tingling sensation in both leg since last 12 months. X-ray of lumbo-sacral region indicated that patient was suffering from reduced L4-L5 intervertebral disc space and bony ankylosis of L4-L5 and degenerative changes in spine. He was taken modern treatment but doesn’t get satisfactory relief even.
 For Ayurvedic treatment he came at opd of kaychikitsa department of Seth Sakharam Nemchand Jain Ayurvedic Hospital, Solapur. He was treated for 21 days with 3 times treatment follow up. The response of the treatment was recorded and therapeutic effects were evaluated through symptomatic relief. Clinical symptoms were significantly reduced and degree of anterior flexion increased from 25˚ to 90 ˚.
 This regimen is effective in successfully treating katishoola by helping to reduce the symptoms and improving the degree of anterior flexion.

A case of localized cervical bony ankylosis due to ulcerative colitis.

A case of localized cervical bony ankylosis due to ulcerative colitis.

A study on clinical outcome of total elbow arthroplasty

Introduction: Prosthetic total elbow arthroplasty (TEA) is a recognised treatment for the painful arthritic elbow. is a challenging procedure for orthopedic surgeons. For elderly patients with deformity and ankylosis of the elbow due to posttraumatic arthritis or rheumatoid arthritis or comminuted fracture distal humerus, arthroplasty is one of the option. The clinical outcome and long-term survivorship differs from implant to implant, and the results obtained with a given linked or unlinked implant cannot be extrapolated to other members of the same implant family.Materials and Methods: 13 cases of total elbow arthroplasty were included in this study, between June 2010 and October 2013. The indications for total elbow arthroplasty in this study were rheumatoid arthritis, comminuted fracture distal humerus with intraarticular extension, and posttraumatic bony ankylosis of elbow joint. Patients with compound fracture around the elbow joint, severely comminuted fracture proximal ulna, flaccid paralysis of the upper limb, non-restorable function of biceps or triceps and patients with high demanding jobs have been excluded from the study. Results: The average operative time was 86.2 minutes (range 64 to 108 minutes). The follow up was from 4 months to 110 months (mean 71 months). The evaluation of the patients was based on clinical as well as on radiological parameters. Pre-operatively four patients had stable elbows as they had ankylosis in non-functional position between 80 to 90° due to rheumatoid arthritis or traumatic arthritis and also stable by virtue of bony fusion. Remaining nine patients had unstable elbows because of fracture distal humerus. Clinico‑radiologically all the elbows were stable. Conclusion: To conclude, a semi constrained total elbow arthroplasty is a predictable and effective method for decreasing pain and restoring function in elderly patients with chronic elbow dislocation or fracture dislocation. The rapid functional improvement provided by this procedure allows patients to return to activities of daily living early.

Conventional versus Modified Preauricular Incision Approaches to the Management of Temporomandibular Joint Ankylosis in Sana’a City, Yemen: A Comparative Clinical Study

Objective: To compare between the conventional and modified preauricular incision approaches to the management of temporomandibular joint (TMJ) ankylosis among Yemeni patients in Sana’a city, Yemen.
 Methods: This comparative clinical study recruited ten patients (7 males and 3 females; age range: 6–35 years) with true fully or partially bony or fibrous TMJ ankylosis. These patients were admitted to and followed up in the Department of Oral and Maxillofacial Surgery, College of Dentistry, University of Science and Technology Hospital in Sana’a in the period from May 2013 to February 2016. Five patients with condylar capsule ankylosis were subjected to the conventional preauricular approach, while the other five cases with ankylosis that extends beyond the condylar capsule and reaches the zygomatic arch were subjected to the modified preauricular approach. Both approaches were evaluated and compared for the time required, intra- and post-operative complications and aesthetic results.
 Results: The mean times required to carry out the operations were 4.45 and 3.20 hours for conventional and modified preauricular approaches, respectively.Facial nerve injury was present in two patients undergoing the conventional preauricular approach, but this reversed to normal after four to five months. Patient of both groups experienced no facial paralysis or post-operative auriculotemporal syndrome. Intra-operative bleeding was mild to moderate among the patients of both approaches, and none of the patients required blood transfusion intra- or post-operatively. Major blood vessels were injured in three cases undergoing the conventional preauricular approach. All patients subjected to both approaches showed satisfactory aesthetic end results.
 Conclusions: Conventional and modified preauricular approaches provide excellent accessibility and visibility to the surgical field during the management of TMJ ankylosis among Yemeni patients, with the latter being slightly superior. In addition, the modified preauricular approach is associated with fewer complications, absence of facial nerve injury and reduced surgical time compared to the conventional approach.

Conventional versus Modified Preauricular Incision Approaches to the Management of Temporomandibular Joint Ankylosis in Sana’a City, Yemen: A Comparative Clinical Study

Objective: To compare between the conventional and modified preauricular incision approaches to the management of temporomandibular joint (TMJ) ankylosis among Yemeni patients in Sana’a city, Yemen.
 Methods: This comparative clinical study recruited ten patients (7 males and 3 females; age range: 6–35 years) with true fully or partially bony or fibrous TMJ ankylosis. These patients were admitted to and followed up in the Department of Oral and Maxillofacial Surgery, College of Dentistry, University of Science and Technology Hospital in Sana’a in the period from May 2013 to February 2016. Five patients with condylar capsule ankylosis were subjected to the conventional preauricular approach, while the other five cases with ankylosis that extends beyond the condylar capsule and reaches the zygomatic arch were subjected to the modified preauricular approach. Both approaches were evaluated and compared for the time required, intra- and post-operative complications and aesthetic results.
 Results: The mean times required to carry out the operations were 4.45 and 3.20 hours for conventional and modified preauricular approaches, respectively.Facial nerve injury was present in two patients undergoing the conventional preauricular approach, but this reversed to normal after four to five months. Patient of both groups experienced no facial paralysis or post-operative auriculotemporal syndrome. Intra-operative bleeding was mild to moderate among the patients of both approaches, and none of the patients required blood transfusion intra- or post-operatively. Major blood vessels were injured in three cases undergoing the conventional preauricular approach. All patients subjected to both approaches showed satisfactory aesthetic end results.
 Conclusions: Conventional and modified preauricular approaches provide excellent accessibility and visibility to the surgical field during the management of TMJ ankylosis among Yemeni patients, with the latter being slightly superior. In addition, the modified preauricular approach is associated with fewer complications, absence of facial nerve injury and reduced surgical time compared to the conventional approach.

Grafts of autogenous coronoid process to reconstruct the mandibular condyle in children with unilateral ankylosis of the temporomandibular joint: long-term effects on mandibular growth

Injury to the mandibular condyle in children usually leads to malocclusion and disharmony of facial growth. Our aim was to study the facial growth after reconstruction of the mandibular condyle using autogenous coronoid process grafts in children with unilateral ankylosis of the temporomandibular joint (TMJ). We followed up 10 growing patients with unilateral bony ankylosis of the TMJ who had been admitted to the West China Hospital of Stomatology, Sichuan University (Chengdu, China) between 1 January 2008 and 31 December 2012. There were three boys and seven girls, age range 5–12 years at the time of operation. In each case, patients were treated by gap arthroplasty, reconstruction of the condyle with an ipsilateral coronoid process, and interposition of the pedicled temporalis fascial flap during one operation. The mean (range) postoperative follow up was 4.73 (3–6) years. Postoperative panoramic radiographs were taken, and the growth of the mandibular height and length on the affected side was measured and compared with the healthy side. All patients had an uneventful, normal recovery. The mean (range) maximal mouth opening at the end of follow up was 35.6 (32–41) mm. Both the height of the ramus and the length of the mandible continued to grow after successful treatment of the ankylosis (using autogenous coronoid process grafts for reconstruction of the condyle) but the deficit in growth was not completely made up. The final height of the ramus on the affected side (at the end of follow up) had increased by 25% (p=0.012) and the final length of the mandible on the affected side by 26% (p=0.010) compared with immediately after operation. For comparison of the rate of growth, the increased height of the ramus of the affected side was 47% lower (p=0.003), while the increased length of the mandible on the affected side was 27% shorter (p=0.008) compared with the healthy side. The mandible on the affected side continued to grow after successful treatment of the ankylosis, but the growth deficit was not made up completely. The rate of growth of the affected mandible seemed to be less than on the undisturbed side even after treatment of the ankylosis.

Primary Asthenic Gout by Augustin-Jacob Landre-Beauvais in 1800: Is this the first description of Rheumatoid Arthritis?

Although Alfred Baring Garrod was the physician who introduced the term Rheumatoid Arthritis, it was the French medical student Augustin-Jacob Landre-Beauvais who firstly described the newly appeared type of arthritis. In his opinion, “Goutte Asthénique Primitive”, as he named it, affected mostly the poor, with bigger prevalence among women, presenting characteristic capsular swelling, limitation of motion of the joints in the hands and fingers, and development of bony ankylosis with disorganisation of many joints. Landre-Beauvais was known for his empathy towards his patients, an acquired feeling due to his internship under Pinel. His greatest treatise “Séméiotique, ou Traité des signes des maladies” was greatly influenced in its structure by the concept of Corpus Hippocraticum.

The Safety and Accuracy of Surgical Navigation Technology in the Treatment of Lesions Involving the Skull Base.

As compared with the normal anatomy, structures of the skull base and its surroundings have been dramatically altered of the lesion near the skull base. How to remove the lesion at the skull base was mainly depending on surgeon's personal experience during past years. In this study, the authors explored the safety and accuracy of the surgical navigation system in resecting lesions near the skull base. The surgical cases consisted of 15 patients who underwent surgery involving the skull base with the using of surgical navigation technology. Five patients had adenoid cystic carcinoma at minor salivary glands of the palate extending to the skull base and 10 patients were suffered from bony ankylosis of temporomandibular joint. After the system converted patient's computed tomography scans into three-dimensional reconstructive images, preoperative planning and simulation of the operation process could be made by surgeons. During the operation, the virtual images were matched with the patient through individual registration. The system provided surgeon with feedback about the operation on the screen instantly with moving the navigated pointer. The application of surgical navigation system was safe and reliable for resecting the ankylotic bone and identifying the extent of tumors resection near the skull base. No complications including cerebrospinal fluid leak, cranial nerve injuries, severe bleeding happened to those patients. Given the safety and accuracy of the surgical navigation system, surgery near the skull base appeared to be an ideal field for using with its complex anatomy.

Total elbow arthroplasty for primary osteoarthritis

Primary osteoarthritis of the elbow is a less common indication for total elbow arthroplasty (TEA). Higher complication rates in younger, active patients may offset short-term improvements in pain and function. The purpose of this study was to determine pain relief, functional outcomes, complications, and survival of TEA in this population. Between 1984 and 2011, 20 consecutive TEAs were performed for primary elbow osteoarthritis. Two patients died before the 2-year follow-up. Mean age at surgery was 68 years (range, 51-85 years). Outcome measures included pain, motion, Mayo Elbow Performance Score, satisfaction, complications, and reoperations. Mean follow-up was 8.9 years (range, 2-20 years). Three elbows sustained mechanical failures. Complications included intraoperative fracture (n = 2), wound irrigation and débridement (n = 1), bony ankylosis (n = 1), humeral loosening (n = 1), humeral component fracture (n = 1), and mechanical failure of a radial head component (n = 1). Fifteen elbows without mechanical failure were examined clinically. Pain improved from 3.6 to 1.5 (P < .001). Range of motion remained clinically unchanged (P > .05), with preoperative flexion contractures not improving. Mayo Elbow Performance Scores were available for 13 elbows without mechanical failure, averaging 81.5 points (range, 60-100 points); these were graded as excellent (n = 5), good (n = 2), and fair (n = 6). Subjectively, all patients without mechanical failure were satisfied. TEA represents a reliable surgical option for pain relief in patients with primary osteoarthritis. However, restoration of extension is not always obtained, indicating that more aggressive soft tissue releases or bony resection should be considered. Complications occurred in a large number of elbows, but mechanical failure was low considering the nature of this population and the length of follow-up.

Accelerated osteogenic differentiation of human bone-derived cells in ankylosing spondylitis.

Ankylosing spondylitis (AS) is characterized by excessive bone formation with syndesmophytes, leading to bony ankylosis. The contribution of osteoblasts to the pathogenesis of ankylosis is poorly understood. The aim of this study was to determine molecular differences between disease controls (Ct) and AS bone-derived cells (BdCs) during osteogenic differentiation with or without inflammation using AS patient serum. We confirmed osteoblastic differentiation of Ct and AS BdCs under osteogenic medium by observing morphological changes and measuring osteoblastic differentiation markers. Osteoblast differentiation was detected by alkaline phosphatase (ALP) staining and activity, and alizarin red and hydroxyapatite staining. Osteoblast-specific markers were analyzed by quantitative reverse-transcriptase-polymerase chain reaction, immunoblotting, and immunostaining. To examine the effects of inflammation, we added AS and healthy control serum to Ct and AS BdCs, and then analyzed osteoblast-specific markers. AS BdCs showed elevated basal intercellular and extracellular ALP activity compared to Ct. When osteoblast differentiation was induced, AS BdCs exhibited higher expression of osteoblast-specific marker genes and faster mineralization than Ct, indicating that these cells differentiated more rapidly into osteoblasts. ALP activity and mineralization accelerated when serum from AS patients was added to Ct and AS BdCs. Our results revealed that AS BdCs showed significantly increased osteoblastic activity and differentiation capacity by regulating osteoblast-specific transcription factors and proteins compared to Ct BdCs. Active inflammation of AS serum accelerated osteoblastic activity. Our study could provide useful basic data for understanding the molecular mechanism of ankylosis in AS.

Changes in craniocervical angulation in patients with temporomandibular joint bony ankylosis

Changes in craniocervical angulation in patients with temporomandibular joint bony ankylosis

New approaches in ankylosing spondylitis.

Free to read on journal website (may need to create free account first) There have been marked improvements in treatment options but none have yet been shown to induce remission The past decade has seen major advances in the diagnosis and management of ankylosing spondylitis (AS) and in research into its pathogenesis. It remains the case that no current treatments have been shown to lead to disease remissions or to halt the progression of the bony ankylosis that causes the major morbidity associated with this condition. Nonetheless, improved diagnostic methods and management have led to major benefits for patients, with marked improvements in quality of life with reduced treatment-associated side effects.

Assessment of the Effect of Temporomandibular Joint Bony Ankylosis on Eustachian Tube Functions

Objective: This study was designed to evaluate the effect of temporomandibular joint (TMJ) bony ankylosis on Eustachian tube (ET) functions. Subjects and Methods: Twelve patients suffering from TMJ bony ankylosis were selected from those attending the out-patient Clinic of Oral and Maxillofacial Surgery Department, Faculty of Oral and Dental Medicine, Cairo University. Twelve subjects (control group) underwent Eustachian tube function test were selected also. Tympanometry was utilized to assess Eustachian tube function. Three pressure reading (P1, P2, and P3) of the middle ear and external ear canal volume were recorded by the use of tympanometry. Comparisons were performed between patient and control group to evaluate the change of pressure. Results: Throughout the results, four ears showed type (C) tympanogram representing Eustachian tube dysfunction, two ears showed type (B) tympanogram which represent otitis media with effusion. While other ears showed type (A) tympanogram. On comparing the pressure values between the patients and the control, significant decrease was recorded in (P2) value in the patients group and no significant difference existed in the external canal volume. Conclusions: The Eustachian tube function is affected in patients of temporomandibular joint bony ankylosis, it cannot adapt to changes in pressure effectively. Patients of TMJ ankylosis are more liable to develop otitis media. Inflation-deflation test is a reliable method for evaluating Eustachian tube function in patients of (TMJ) ankylosis. The external ear canal volume was not affected in this group of patients.

Zygomatico-Coronoid Ankylosis: A Case Report

Extra-articular ankylosis resulting from bony union between the coronoid process and the zygoma is very rare. It may result from facial fractures caused by gunshots, treated or untreated facial fractures or may arise as an extension of intracapsular ankylosis. We report a case of ankylosis between the coronoid process and the zygomatic arch in a 33-year-old Black male. The bony ankylosis was the result of a 2 year old untreated zygomatic arch fracture. Ankylosis developed secondary to heterotopic bone formation following trauma. The patient was treated by intra-oral coronoidectomy, followed by physiotherapy for three months. He returned for review one year later with a mouth-opening of 40 mm and a stable occlusion.

Correlation between hemoglobin concentration and hematocrit values in patients with temporomandibular joint ankylosis and nonankylosed patients

Background: Temporomandibular joint (TMJ) ankylosis causes distortion of the anatomy of the upper airway resulting in some form of airway obstruction. Aim: The aim of this study was to determine the relationship between TMJ ankylosis and hemoglobin and hematocrit levels. Settings and Design: This was a prospective comparative study of all consecutive patients with TMJ ankylosis who presented to the Oral and Maxillofacial Unit of the Teaching Hospital from January 2010 to December 2012. Materials and Methods: Information obtained included age, gender, types of ankylosis, etiology, duration of ankylosis as well as the hemoglobin and hematocrit values which were compared with age- and sex-matched nonankylosed patients. P ≤ 0.05 was considered statistically significant. Results: Twenty patients aged 10–35 years (mean 20.8 ± 5.53) comprising 55.0% males and 45.0% females participated in the study. Bony ankylosis was the most common presentation (75.0%) while trauma (55.0%) was the most common etiologic factor. The mean duration of ankylosis was 9.05 ± 5.43. The mean hemoglobin concentration was 13.49 ± 1.67 and the mean hematocrit was 39.35 ± 5.63. There was a positive correlation between the duration of ankylosis and the hemoglobin concentration (r = 0.471, df = 17, P= 0.042) as well as the hematocrit values (r = 0.457, df = 17, P= 0.049). Both hematological parameters were found to be significantly higher than the values in the nonankylosed patients with a mean difference of 1.57 g/dl (P = 0.001) and 6.28% (P = 0.0001) for hemoglobin concentration and hematocrit values, respectively. Conclusion: Patients with TMJ ankylosis have higher values of hemoglobin concentration and hematocrit values than the nonankylosed individuals and these findings can be explored for the clinical benefit of patients.

Bony ankylosis of the facet joint of the cervical spine in rheumatoid arthritis: Its characteristics and relationship to the clinical findings

Objectives: The purpose of this study was to clarify the characteristics of bony ankylosis of the facet joint of the cervical spine in rheumatoid arthritis (RA) patients who required cervical spine surgery, and its relationship to the clinical findings.Methods: Eighty consecutive RA patients with cervical spine disorder who received initial surgery were reviewed. The occurrence of bony ankylosis of the facet joint of the cervical spine was investigated using computed tomography (CT) before surgery. We also evaluated the severity of neurological symptoms and the plain wrist radiographs taken before surgery; furthermore, we evaluated each patient’s medical history for total knee arthroplasty (TKA) or hip arthroplasty (THA).Results: The preoperative CT imaging demonstrated bony ankylosis of the facet joint of the cervical spine in 45 facet levels of 19 cases (BA + group). In all patients, responsible instability or stenosis was demonstrated just caudal or on the cranial side of those bony ankylosis. Before surgery, the BA + group included significantly more patients showing severe cervical myelopathy (p < 0.05), and significantly more cases showing progressed ankylosis in the wrist joint bilaterally (p < 0.01). There were also significantly more patients who received two or more TKA or THA before the cervical spine surgery in the BA + group (p < 0.01).Conclusions: Bony ankylosis of the facet joint of the cervical spine may be a risk factor of instability or stenosis at the adjacent disc level and severe cervical myelopathy. Furthermore, its ankylosis was demonstrated in RA patients with severe destroyed joints.

Unilateral Acquired Posterior Maxillary Mandibular Syngnathia

Introduction: Congenital bony fusion of the maxilla and mandible, especially as an isolated occurrence, is a rare condition while acquired fusion being even rarer.&#x0D; Case report: A rare case of a 32 year old female patient with acquired unilateral bony fusion between the zygomatic arch of maxilla and ramus of mandible is reported.&#x0D; Discussion: Forty one cases of syngnathia has been reported in the international literature from 1936 to 2009, of which 39 cases are congenital and two were acquired, case 1 probably as a result of a fibrotic tubed pedicle and in case 2 from myositis ossificans. According to several case series, bony ankylosis of the mandible and maxilla has also been found to occur in 30%-43% of cases of NOMA.

Application of a computer-assisted surgical navigation system in temporomandibular joint ankylosis surgery: a retrospective study

This retrospective study evaluated the effect of surgical computer-assisted navigation in temporomandibular joint (TMJ) ankylosis gap arthroplasty. Eighteen patients (25 sides) with bony ankylosis who underwent surgical treatment under computer-assisted navigation (navigation group) from May 2011 to April 2013 were assessed, along with 19 such patients (25 sides) treated without computer-assisted navigation (non-navigation group) from March 2009 to April 2011. The navigation group patients underwent surgery with the preservation of ≥3mm bone thickness in the skull base and anterior wall of the external auditory canal. Postoperatively, computed tomography (CT) was used to measure the residual bone thickness in the skull base and anterior wall of the external auditory canal. Maximum mouth opening (MMO) changes were evaluated at >1 year of follow-up. Postoperative CT measurements showed that the lowest skull base thickness in the navigation group was significantly lower than that in the non-navigation group (3.86±1.95mm vs. 6.01±3.07mm, P=0.009). The lowest thicknesses of the anterior wall of the external auditory canal were similar in the two groups. Postoperative follow-up showed similar average MMO in the two groups. Therefore, with the navigation system, TMJ ankylosis gap arthroplasty can achieve more extensive removal of the ankylosed bone, at least towards the skull base, under the premise of ensuring a safety distance of 3mm.