Magnetic Resonance Imaging for Temporomandibular Joint Internal Derangement and Osteoarthritis – A Prospective Study

Abstract

Introduction:

Management of temporomandibular joint (TMJ) osteoarthritis (OA) is a challenging issue in modern gnathology and maxillofacial surgery. Identifying various signs of TMJ OA, their relationship with internal derangement and studying the features of combined (uni-, bilateral) pathology contribute to an accurate assessment of TMJ condition and appropriate management. Conventionally, besides clinical examination, this state was diagnosed by computed tomography. However, magnetic resonance imaging (MRI) allows the assessment of both bone and soft tissue. The aim of the study was to identify the correlation between degenerative changes in bone structures and various forms of internal TMJ disorders based on MRI data, as well as to assess the morphofunctional changes in the TMJ in cases of uni-, bilateral joint pathology.

Materials and Methods:

Two hundred and twenty-two patients (444 joints) underwent a clinical examination and MRI of the TMJ (Siemens Magnetom Verio MRI scanner Germany 3.0 T). Exclusion criteria included systemic diseases, joint trauma and prior treatments.

Results:

Osteodegeneration predominated in cases of anterior disc displacement without reduction (ADDWoR): osteophytes on the condylar head (74.8%), flattening (40.2%), erosions (31.8%) and subchondral sclerosis (88.8%). As the degree of disc displacement progressed, the decrease of volume of condyle, changed from 373.8 mm² with normal disc position (NDP) to 251.3 mm² with ADDWoR. In cases with NDP, unilateral OA was present in 2.3% of and bilateral OA in 4.1%. Bilateral displacement is characterised by bilateral OA in 26.1%, whereas unilateral OA in 12.2%. There is a positive correlation between the position of the disc in the sagittal projection and degenerative changes.

Discussion:

Strong correlation was identified between degenerative changes in the bone structures of the TMJ and various types of internal disorders.

INTRODUCTION

Diagnosis and treatment of temporomandibular joint (TMJ) osteoarthritis (OA) remain among the most pressing issues in modern gnathology and maxillofacial surgery. Recent studies have highlighted a close correlation between the types of disc displacement and the onset of degenerative bone changes.[1,2] TMJ OA is characterised by multifactorial aetiology.[3,4,5] This disrupts the balance between the joint’s adaptive capacity and the forces acting on the joint, leading to dysfunctional remodelling, which can result in changes in the shape, size and volume of the mandibular condyle.[6] Bone manifestations of TMJ OA include flattening, osteophyte formation, sclerosis, erosions, osteochondral bodies and subchondral bone cysts.[7,8,9]

The identification of signs of TMJ OA, as well as understanding the features of combined (uni-, bilateral) pathology, can facilitate a more precise assessment of the joint’s condition and the development of an appropriate treatment strategy.

Thus, the aim of this study was to identify the correlation between degenerative changes in bone structures and various forms of internal TMJ disorders based on magnetic resonance imaging (MRI) data, as well as to assess the morphofunctional changes in the TMJ in cases of uni-, bilateral joint pathology.

MATERIALS AND METHODS

A total of 222 patients were involved in the study, selected from individuals who presented with complaints related to the TMJ at the Central Clinical Hospital of Baku. All procedures performed in the study were conducted under the ethical standards given in the 1964 Declaration of Helsinki, revised in 2013, as well as the Ethical Committee of Azerbaijan Medical University, Faculty of Dentistry Protocol N 15. Of the 222 patients, 46 (20.7%) were male, and 176 (79.3%) were female. The average age of the patients was 33.6 ± 0.9 years. A total of 444 joints were examined.

The list of complaints included local joint pain (28 patients; 12.6%), restriction or lock during mouth opening (151 patients; 68%), crepitus and/or specific clicks during mouth opening (162 patients; 72.9%), deviation of the mandible during mouth opening (44 patients; 19.8%), tenderness upon palpation of the joint area (16 patients; 7.2%), bite changes (174 patients; 78.3%) and facial swelling on the affected side (4 patients; 1.8%). Inclusion criteria included complaints related to the TMJ, absence of contraindications for MRI (claustrophobia, metallic implants, pacemakers). Exclusion criteria included systemic diseases, trauma or surgical interventions in TMJ.

MRI was performed on a Siemens Magnetom Verio MRI scanner with a magnetic field strength of 3.0 T. A standard 16-element radiofrequency neurovascular coil for head scanning was used for the MRI of the TMJ.

The joints were divided into groups:

• Group 1 (Control Group; n = 182 joints): Consisted of joints with normal disc position (NDP) (182 joints)

• Group 2 (n = 148): Included joints with anterior disc displacement with reduction (ADDWR) during mouth opening

• Group 3 (n = 107): Included joints with anterior disc displacement without reduction (ADDWoR) during mouth opening

• Group 4 (n = 7): Included joints with posterior disc displacement with reduction (PDDWR) during mouth opening.

Statistical analysis methods included variation for quantitative indicators (t-student-Bonferroni test, non-parametric Mann–Whitney U-test and median Kruskal–Wallis H-test), Pearson Chi-square test for qualitative indicators analysis, analysis of variance (ANOVA test), F-Fisher test, correlation analysis between quantitative and qualitative indicators performed with the ρ-Spearman test. Calculations were performed in SPSS version 26 statistical package (IBM Corp., Armonk, NY, USA).

RESULTS

When considering the difference between the control group and patients with disc dislocation, the distribution of subjects by age criteria deserved attention [Table 1]. Within this study, 222 patients were examined: 46 (20.7%) were male, 176 (79.3%) were female. In the control group, women predominated (71; 74.0%), while the number of male patients was 25 (26.0%). A similar trend was observed in groups with different types of articular disc dislocation: in the group with ADDWR, there were 61 (83.6%) women and 12 (16.4%) men, in the group with ADDWoR, there were 44 (88.0%) women and 6 (12%) men. The inverse relationship was found only among patients with PDDWR: in this group, the pathology occurred in men (3; 100%), whereas posterior disc dislocation was not observed in female patients.

Table 1.

Distribution of patients by age groups

Age groups (years)	Normal disc position, n (%)	Disc dislocation, n (%)
<20	5 (5.2)	19 (15.1)
20–29	21 (21.9)	48 (38.1)
30–39	33 (34.4)	34 (27.0)
40–49	20 (20.8)	12 (9.5)
50–59	9 (9.4)	10 (7.9)
≥60	8 (8.3)	3 (2.4)

Out of 444 joints, one or more signs of OA were observed in 219 (49.3%) patients. In the group with NDP, out of 182 joints, 44 (24.2%) exhibited one or more signs of OA. In cases of displaced discs, at least one sign of OA was found in 175 (66.8%) joints. The evaluation of OA by patient groups revealed that the highest frequency of this change occurred in the group with ADDWoR (90; 84.1%). The second-most common occurrence was in the group with ADDWR (82; 55.4%). The lowest percentage was found in the group with NDP (44; 24.2%), with OA not being an expected finding in cases without disc displacement. In the group with PDDWR, OA was found in nearly half of the cases (3; 42.9%) [Figure 1]. However, it should be noted that this group had the smallest number of patients due to the rarity of this pathology.

Figure 1.

Woman, 62 y. o. Sagittal Proton Density Fat-Sat (PDFSat) WI. A) right temporomandibular joint (TMJ) Normal position of the intra-articular disk in the closed (a) and open (b) mouth positions, B) left TMJ. Anterior disk displacement in the closed mouth position (a) without reduction during mouth opening (b). Sharpening of the anterior contour of the condyle, pronounced subchondral degenerative cystic changes. The disk is deformed to a conglomerate state

Out of 444 joints, flattening of the mandibular condylar head was identified in 80 (18.0%) joints. In the group with pathological disc position, this sign predominated compared to the group with a NDP (25.2% and 7.7%, respectively), which is logical according to the above classification. However, since this indicator is a transitional sign of OA, its timely assessment is important. In our study, the analysis was performed according to different types of disc displacement, which showed the following distribution [Table 2]. According to the results, there was a significant difference between groups, which was reflected in the percentages. The highest percentage was found in ADDWoR (40,2%), while the lowest was found in joints with NDP (7.7%).

Table 2.

Percentage ratio of the condyle flattening presence

Flattening	NDP, n (%)	ADDWR, n (%)	ADDWoR, n (%)	PDDWR, n (%)	χ 2	P-value	PU
No	168	126 (85.1)	64 (59.8)	6 (85.7)	49,799	<0.001	<0.001
Yes	14 (7.7)	22 (14.9)	43 (40.2)	1 (14.3)

PU - Statistical significance of differences between patient groups according to Mann–Whitney U-test. NDP: Normal disc position, ADDWR: Anterior disc displacement with reduction, ADDWoR: Anterior disc displacement without reduction, PDDWR: Posterior disc displacement with reduction

Condyle marginal osteophytes were identified in 163 (36.7%) cases, of which 142 joints (54.2%) belonged to joints with a pathological position of the disc [Figure 2]. Moreover, the sign was detected predominantly in joints with ADDWoR (74.8%). There were significant differences between groups (P <0.001) [Table 3].

Figure 2.

Woman, 33 y. o. Sagittal Proton Density Fat-Sat (PDFSat) WI. A) Right temporomandibular joint (TMJ). Normal position of the intra-articular disk in the closed (a) and open (b) mouth positions. Hypomobility. B) Left TMJ. Anterior disk displacement in the closed mouth position (a) without reduction during mouth opening (b). Decrease in the size of the articular disk. Osteophytes, subchondral sclerosis, and erosions of the mandibular condyle. Hypomobility

Table 3.

Condyle marginal osteophyte indicators in study groups

Osteophyte	NDP, n (%)	ADDWR, n (%)	ADDWoR, n (%)	PDDWR, n (%)	χ 2	P	PU
No	161 (88.5)	52 (54.2)	26 (24.8)	6 (85.7)	119,138	<0.001	<0.001
Yes	21 (11.5)	44 (45.8)	79 (75.2)	1 (14.3)

PU - Statistical significance of differences between patient groups according to Mann–Whitney U-test. NDP: Normal disc position, ADDWR: Anterior disc displacement with reduction, ADDWoR: Anterior disc displacement without reduction, PDDWR: Posterior disc displacement with reduction

Erosion of the condyle was found in 48 (18.3%) out of 444 joints, and all of these joints had abnormal disc positioning. Similarly, regarding the presence of osteophytes on the mandibular condyle, this sign was more prevalent in joints with ADDWoR (34; 31.8%). In the group of joints with ADDWR, erosions were observed in 14 joints (9.5%). Among the joints with PDDWR, this sign was absent. This may be explained by the lesser trauma to the mandibular condyle in cases of posterior disc displacement compared to other types of disc displacement. Erosion, as a manifestation of TMJ pathology, is characterised by a statistically significant intergroup difference (χ² = 71.965; P < 0.001; PU < 0.001) [Table 4].

Table 4.

Present of erosions percentage ratio in the group of surveyed

Erosions	NDP, n (%)	ADDWR, n (%)	ADDWoR, n (%)	PDDWR, n (%)	χ 2	P	PU
No	182 (100.0)	134 (90.5)	73 (68.2)	7 (100.0)	71.965	<0.001	<0.001
Yes	0	14 (9.5)	34 (31.8)	0

PU - Statistical significance of differences between patient groups according to Mann–Whitney U-test. NDP: Normal disc position, ADDWR: Anterior disc displacement with reduction, ADDWoR: Anterior disc displacement without reduction, PDDWR: Posterior disc displacement with reduction

Subchondral sclerosis of the mandibular condyle was identified in 263 (59.2%) cases. Among the joints with this sign, 56 joints (30.8%) had normal disk position, whereas 207 joints (79.0%) had abnormal disk positioning. Subchondral sclerosis of the mandibular condyle was also predominantly observed in joints with ADDWoR during mouth opening (88.8%) [Table 5]. According to our data, such changes in the morphology of the condylar head were observed with almost equal frequency in cases of ADDWR and PDDWR. However, it is possible that the high percentage in Group 4 is due to the small number of joints in this group. Signs of osteodegeneration predominated in cases of ADDWoR: osteophytes (74.8%), flattening (40.2%), erosions (31.8%) and subchondral sclerosis (88.8%) of the condyle [Figure 3]. In cases with NDP, unilateral OA was present in 2.3% of patients and bilateral OA in 4.1% of patients. As the degree of disc displacement progressed, there was a decrease in the volume of the condyle, from 373.8 mm² with a NDP to 251.3 mm² with ADDWoR.

Table 5.

Present of condyle subchondral sclerosis percentage ratio in the group of surveyed

Sclerosis	NDP, n (%)	ADDWR, n (%)	ADDWoR, n (%)	PDDWR, n (%)	χ 2	P	PU
No	126 (69.2)	41 (27.7)	12 (11.2)	2 (28.6)	110,655	<0.001	<0.001
Yes	56 (30.8)	107 (72.3)	95 (88.8)	5 (71.4)

PU - Statistical significance of differences between patient groups according to Mann–Whitney U-test. NDP: Normal disc position, ADDWR: Anterior disc displacement with reduction, ADDWoR: Anterior disc displacement without reduction, PDDWR: Posterior disc displacement with reduction

Figure 3.

Woman, 18 y.o. Sagittal Proton Density Fat-Sat (PDFSat) WI. A) right temporomandibular joint (TMJ). Anterior disk displacement in the closed mouth position (a) with reduction during mouth opening (b). Hyper mobility. B) left TMJ. Anterior disk displacement in the closed mouth position (a) without reduction during mouth opening (b). Degeneratively altered, deformed disk. Severe flattening of the condyle, deformation, and sharpening of the anterior contour

Bilateral disc displacement was characterised by bilateral OA in 26.1% of cases, while unilateral OA was observed in 12.2%. Thus, the study of the morphological features of the TMJ, its individual structures and function, as well as the presence of pathological changes of an inflammatory and degenerative nature, showed that depending on the position of the TMJ disk, the above-mentioned indicators may vary. The correlative analysis revealed significant relationships between some indicators.

Thus, condylar flattening correlated both with osteophytes on the condylar surface (ρ =0.555; P < 0.001) and with erosions (ρ = 0.535; P < 0.001) and sclerosis (ρ = 0.294; P < 0.001). The high degree of significance of these correlations reflects different stages of OA in TMJ. One obvious manifestation of the above is the correlation between erosions and sclerosis (ρ = 0.289; P < 0.001), osteophytes and erosions (ρ = 0.412; P < 0.001) osteophytes and sclerosis (ρ = 0.489; P < 0.001).

The patient’s age correlated with such an indicator as the «condyle area», which changes during osteodegenerative processes. The correlation between these indicators was positive (ρ = 0.157; P = 0.001). A statistically significant negative correlation was found between age and disc position (ρ = −0.195; P <0.001), which characterises disc displacement. The study of OA signs revealed that in 48 (21.6%) patients with NDP on both sides, no signs of OA were present. At the same time, bilateral OA in the context of NDP was observed in 9 (4.1%) patients. The remaining patients in the group with NDP had unilateral OA (5 patients, 2.3%).

In cases where disc displacement was observed on one side and the disk position was normal on the other, the number of patients with bilateral OA was 19 (8.6%). In the same situation, the absence of OA on both sides was noted in 24 (10.9%) patients. Meanwhile, in patients with unilateral disc displacement, OA in one of the joints was observed in 15 (6.8%) cases. Bilateral disc displacement was characterised by the absence of OA in both joints in 17 (7.7%) patients, whereas OA was present in both joints in 58 (26.1%) cases. In the same group, unilateral OA was observed in 27 (12.2%) patients.

DISCUSSION

TMJ dysfunction is a pressing problem due to its relatively high frequency (up to 15% of adults suffer, ages 20 and 40), as well as due to the risk of developing degenerative processes.[10] Bone changes of the TMJ were described in 71% of patients examined by a radiologist in Brazil over a 1-year period.[11] In addition, a 2012 study of 117 asymptomatic participants also found that 100 (42.7%) TMJs had some visible remodelling in the condyle.[12] However, the presence of bone changes does not equate to degenerative changes, and changes should be analysed in the clinical context.[13] From this perspective, in our study, complaints (ranging from local joint pain to bite changes and facial swelling on the affected side) were present, which may indicate degeneration.

In another study, Ottersen et al.,[14] examined 159 individuals (86 women and 73 men) randomly selected from a cohort of 460 residents of Oslo, assessing prevalence, gender differences and characteristics of TMJ imaging features using cone beam computed tomography (CBCT). According to the results, features were found in 35% of the 159 participants: 47% of women and 22% of men, were unilateral in two-thirds of the TMJ and were characterised by flattening of the articular surface and condylar osteophytes. Almost all joints with erosive features of bone tissue also showed bone-productive features.

In our study, features of osteodegeneration were found in 219 (49.3%) of 444 joints (175 (66.8%) with disc displacement and 44 (24.2%) with NDP. 26.1% of 222 patients had uni- and 12.2% had bilateral signs. However, it should be noted that the above study examined 65-year-old patients, while in our study, the age range was from <20 to ≥60 years, and MRI was used, which, in our opinion, allowed for a more targeted and comprehensive examination.[14]

Miyagishima et al., (2025)[15] analysed three-dimensional cephalometric characteristics of skeletal mandibular retrusion using CT in 15 patients with and 15 without OA. The results showed that the mean condyle volume was significantly lower in OA (851.1 mm3) than in the absence of OA (1151.3 mm3) (P < 0.001), which is consistent with our results. Unlike this work, we used MRI and assessed the condyle area, but this does not change the concept supporting the assumption of the relationship between internal changes in the TMJ structures and osteodegeneration processes.[15] Gil et al., using MRI scans of 74 symptomatic patients with at least one sign or symptom of TMJ disorder reported erosion signs in 13 out of 148 TMJ.[16] In our study, we found erosions in 48 (18.3%) out of 444 joints by MRI, and additionally, performed comparative analysis among various types of disc dislocation. The results showed statistically significant intergroup difference (χ² = 71.965; P < 0.001; PU < 0.001)

Eriksen et al., performed a retrospective analysis of 79 patients with clinical TMJ disorder or diagnosed inflammatory arthritis and compared them with 26 healthy volunteers. The authors aimed to evaluate a clinically appropriate staging system for MRI evaluation of the TMJ and to identify the association between age and some clinical symptoms of TMJ. The results of the study showed that patients with clinical complaints of TMJ had statistically significantly more anterior disc displacement, disc deformation, head flattening, surface destruction, osteophytes and head oedema diagnosed by MRI compared with the control group. In the control group, disc deformation and the presence of osteophytes increased significantly with age. In our study, such a tendency was not traced in the age aspect; however, the fact that in the group of joints with a NDP, signs of OA were found (24.2%) coincides with the opinion of the authors that some findings are not due to pathological changes but may be age-related degenerative changes.[17]

We believe that there is a need to develop a clinically useful staging system using MRI for effective assessment of osteodegenerative changes in the TMJ. The works reviewed above are based mainly on CBCT, while MRI-based studies are very few and contradictory. In this regard, the relevance of our work and the prospects for its continuation to work out the details are of undoubted importance.

CONCLUSION

1. Signs of osteodegeneration predominated in cases ADDWoR during mouth opening: osteophytes on the condylar head of the mandible (74.8%), flattening of the condylar head (40.2%), erosions (31.8%) and subchondral sclerosis (88.8%). As the degree of disc displacement progressed, there was a decrease in the volume of the condyle, from 373.8 mm² with a NDP to 251.3 mm² with ADDWoR

2. In cases with NDP, unilateral OA was present in 2.3% of patients and bilateral OA in 4.1% of patients, along with various types of kinematic disorders in 19% of the subjects. Bilateral disc displacement was characterised by bilateral OA in 26.1% of cases, while unilateral OA was observed in 12.2%

3. There is a positive correlation between the position of the articular disc in the sagittal projection (disc dislocation) and degenerative changes (condyle flattening (ρ = 0.247; P < 0.001), osteophytes (ρ = 0.451; P < 0.001), erosions (ρ = 0.316; P < 0.001) and sclerosis (ρ = 0.481; P < 0.001).

Based on the conducted study, a strong correlation was identified between degenerative changes in the bone structures of the TMJ and various types of internal disorders.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.