Is TMJ Internal Derangement a Specific Diagnosis or a Non-Specific Sign of Tissue Damage Associated with a Diverse Group of Pathologies?

Classification systems for TMJ disease, such as the Diagnostic Criteria for TMDs¹, refer to disc disorders as a specific diagnostic category.  Joint overload from masticatory parafunction causing inflammatory/degenerative tissue change is very common in patients with symptomatic internal derangement.  However, the TMJ is a synovial joint and subject to various pathologic entities with different etiologies.²   The presence of disc displacement in TMJ disorders with different etiologies would suggest that internal derangement is a sign of intra-articular tissue failure and not a specific diagnosis.   The aim of this study was to determine if internal derangement is present in a wide variety of TMJ pathologies, representing a sign of tissue damage resulting in biomechanical dysfunction, rather than a specific disease.

The study population included 100 consecutive patients with significant pain and mandibular dysfunction resistant to non-surgical treatment with signs of internal derangement based on clinical examination, MRIs and arthroscopic disc position.  Arthroscopy of 100 joints documented the presence of pathologic tissues including synovitis, osteoarthritis, adhesions, anterior disc position, synovial villi, chondromatosis, crystal deposition and pathologic tissue that did not fit the aforementioned categories.  Arthroscopic biopsies were performed on all pathologic tissues.  Following the completion of arthroscopy and recovery of histopathologic findings, each joint was classified into one of three major diagnostic categories: Inflammatory/degenerative- joints with common arthroscopic findings (disc displacement, synovitis, osteoarthritis, and adhesions), histopathology demonstrating inflammatory tissue, and joint overload as the major etiology.  Systemic- TMJ disorder with systemic disease as the major etiology, confirmed with arthroscopic and/or histopathologic findings.  Atypical/localized-joints with rare arthroscopic and histopathologic findings, disease localized to the TMJ and not due to systemic disease or joint overload.  Fisher’s exact probability test was applied to the data to determine if there were any significant differences in the presence of internal derangement in the major diagnostic categories.

The mean age of the study population was 40 with a 1:9 male:female ratio.   Typical inflammatory/degenerative TMJ disease was present in 78% of joints and this group had arthroscopic and histologic findings consistent with synovitis, adhesions and inflammation.  Systemic disease was present in 13% of TMJs, including:  psoriatic arthritis, Lyme disease, chondrocalcinosis, hyperparathyroidism, rheumatoid arthritis and systemic lupus erythematosus.  Atypical/localized TMJ disease was present in 9% of joints including histopathologic and arthroscopic findings such as synovial chondromatosis, crystal deposition and synovial villi.   Arthroscopic diagnosis and/or MRI findings demonstrated internal derangement in 87/100 (87%) of all joints; with internal derangement present in 70/78 (90%) of the inflammatory/degenerative group; 11/13 (85%) of the systemic group; and 6/9 (67%) of the atypical/localizedgroup (Figure 1).  Statistical analysis confirmed that there were no significant differences between the diagnostic groups and the presence of internal derangement.

These findings demonstrate that internal derangement is extremely common in TMJs that are symptomatic due to different etiologies.  Since the temporomandibular joint is a synovial joint, it is susceptible to the variety of disorders that affect all synovial joints.²   Patient symptoms include any combination of pain, limitation of mobility, and joint noises, however, these signs and symptoms are not specific to any disease category.  Internal derangement is not a specific disease entity, but represents a non-specific sign of damaged intra-articular tissues present in a variety of pathologies.  Although clinical examination and MRI findings may confirm an internal derangement, this should not be considered a specific diagnosis that dictates treatment.  Arthroscopic examination-biopsy is an excellent modality to help establish the correct diagnosis and etiology leading to appropriate treatment.  

1.  Peck CC, et al.  J Oral Rehabil.  41(1):2-23, 2014.

2.  Aliko A, et al.  Int J Oral Maxillofac Surg. 40(7):704-9, 2011.