A clinical study on the incidence of internal derangement of the temporomandibular joint following harvesting of temporalis fascia

ABSTRACT

Objective

The aim of the current clinical study was to reveal whether harvesting of a temporalis fascia graft would be associated with a higher incidence of temporomandibular joint (TMJ) internal derangement.

Methods

The study group involved 104 patients who had middle-ear operations, 67 of which involved harvesting of temporalis fascia and 37 that did not. The TMJs were clinically examined in each group.

Results

The total incidence of internal derangement of the TMJ was significantly higher in the group that had temporalis fascia harvesting (79.1%), compared to the group that did not have temporalis fascia harvesting (29.7%), (p= 0.001).

Conclusion

Harvesting of temporalis fascia probably alters mandibular kinematics and predisposes to internal derangement of the TMJs.

KEYWORDS:

• Temporomandibular joint
• disc displacement
• middle ear operations
• temporalis fascia

Introduction

The human masticatory system consists of the mandible, which is able to move in relation to the skull through contractions of the masticatory muscles. The mandible is capable of motion in six degrees of freedom, being guided by the two temporomandibular joints (TMJs), translating along, and rotating about, the three cartesian axes [1–4]. The TMJ articular surfaces are highly incongruent, being separated by an intra-articular disc, which is capable of reducing friction and distributing stresses in the highly loaded joint [5–7]. Both TMJs are loaded during mastication, with different neuromuscular recruitment patterns determining the forces, vectors, and torques acting on the mandible [8,9].

The temporalis muscle, one of the muscles involved in movement of the mandible, has extensive attachment sites [10,11]. Apart from its bony attachments, it gains origin from the temporalis fascia [12,13]. Additionally, muscle bundles from different parts of the temporalis muscle attach to the anterior aspect of the intra-articular disc, which are presumed to stabilize the disc on the mandibular condyle during condylar movements [14,15]. Various anatomical, histological, and electromyographic studies have demonstrated that the temporalis muscle is functionally heterogeneous, with different parts of the muscle performing different actions, depending on the task being performed [16–18].

Various classic middle-ear operations involve harvesting of a temporalis fascia graft. These include canal-wall-down mastoidectomy (where the graft is used to line the cavity and repair the tympanic membrane), as well as temporalis fascia myringoplasty [19,20]. More recently, endoscopic middle-ear surgery, without harvesting of temporalis fascia, is increasingly being performed for chronic otitis media [21,22]. Based on the wide attachment of the temporalis muscle to the temporalis fascia, removal of a large segment of temporalis fascia would putatively affect the temporalis muscle kinematics due to a pure mechanical effect or due to the associated inflammatory response [23,24]. Additionally, pain-related effects might affect the dynamics of the whole masticatory muscle system, even for a long period after the operation [25–27]. These alterations in masticatory muscle kinematics might predispose to alterations in the stress-strain patterns inside the TMJ(s), thereby predisposing to internal derangement of the joint [28–30]. Also, possible dysfunction of temporalis muscle bundle attachments to the TMJ disc, following the operation involving harvesting of temporalis fascia, could predispose to alterations in disc-condyle complex stability during mandibular movements [31–33]. Hence, the alterations in muscle vectors acting on the TMJ(s), following harvesting of the temporalis fascia, might predispose to internal derangement of the joint.

The aim of the current clinical study was to test the hypothesis that middle-ear operations involving harvesting of the temporalis fascia would be associated with a higher incidence of internal derangement of the TMJ(s), in comparison to middle-ear operations where the fascia was not harvested. As far as the author is aware and, after a PubMed literature search from 1970 until 2021, no previous study has addressed this issue.

Materials and methods

The current study was a clinical study performed on patients who had various surgical operations on the middle-ear cleft. The study period was 6 months, starting on 1/5/2021. Appropriate ethical approval for the study was obtained from the General Organization of Teaching Hospitals and Institutes in Cairo (Approval number: 78/2021). The study setting was the otolaryngology clinic at EL-Sahel Teaching Hospital in Cairo. Patients consecutively presenting to the clinic, who had previous middle-ear operations, were included in the study. Informed consent from the patients or their guardians was obtained to participate in the study. To be included in the study, the date of the operation had to be at least 6 months prior to examination. Exclusion criteria were patients who had craniofacial malformation, previous trauma to the head, or operations on the jaw. Patients who only had ventilation tube insertion were also excluded from the study.

A standard clinical symptom and examination findings protocol was completed by the author for each patient. The age and sex of the patient were noted. The date of the operation and nature of the procedure were identified from the hospital records. For the purpose of the current study, patients who had a previous middle-ear operation were classified into two groups: those who had, and those who did not have, harvesting of the temporalis fascia during the procedure. For each patient, a standard questionnaire was completed, including the presence or absence of headache, otalgia, jaw pain, neck pain, previous open-lock, or closed-lock, as well as the presence or absence of jaw sounds during movement of the mandible. Otoneurological symptoms, including hearing loss, tinnitus, and vertigo were also recorded. Other recorded symptoms included bruxism, sleep disorders, and any affective disorders.

Examination of the patient started with inspection of the surgical scar around or in the ear. Any depression in the mastoid process in the ear operated on signified a previous mastoidectomy. Otoscopic appearance of the tympanic membrane, ear canal, and any open mastoid cavity was noted. Next, manual palpation of the TMJs was performed while the patient repeatedly opened and closed the mouth. A palpable and audible click was interpreted as a reducing disc displacement [34]. The presence of tenderness over the joint was described as arthralgia. A crepitus on the joint was interpreted as degenerative joint disease [35]. Where the patient noted that he/she frequently heard sounds during mandibular movements, and no sounds were noted by the examiner, auscultation of the joint, using a stethoscope, was performed to detect any abnormal sound during mandibular movement [36]. Tenderness over the masseter or temporalis muscles was reported as myalgia. Next, any limitation of opening the mouth (interincisal distance less than 40 mm), with or without deviation of the jaw, in the setting of disc pathology, was noted as disc displacement without reduction (closed-lock) [37]. A previous history of inability to close the mouth after wide opening was interpreted as a previous TMJ dislocation (open-lock) [38]. Finally, a comparison was made between the prevalence of internal derangement of the TMJs in the group that had harvesting of temporalis fascia versus the group that did not have harvesting of temporalis fascia.

Statistical analysis

Results were expressed as mean ± standard deviation or number (percent). Comparison between categorical data [n(%)] was performed using the chi square test. Comparison between mean values of age in the two groups was performed using the unpaired t-test. Statistical analysis was performed using the SPSS computer program (version 19 Windows). P-value ≤0.05 was considered significant.

Results

During the study period, 104 patients who had various middle-ear operations were encountered by the author. These were sub-classified into 67 patients who had harvesting of the temporalis fascia and 37 patients who did not have harvesting of the temporalis fascia. The demographic data of the two studied groups are shown in Table 1. Whereas there was no significant difference in the gender between the two groups, the group that did not have temporalis fascia harvesting had a significantly lower mean age than the group that did have harvesting of the temporalis fascia.

Table 1. Demographic data of the two studied groups

	Temporalis fascia harvesting (n = 67)	No temporalis fascia harvesting (n = 37)	p-value
Age (yrs.)
Min.-max.	7.0–69.0	7.0–65.0
Mean ± SD	37.2 ± 14.1	28.9 ± 16.8	0.009*
Gender
Female	36 (53.7%)	22 (59.5%)	0.573
Male	31 (46.3%)	15 (40.5%)

Data are expressed as mean ± SD or number (%). SD: Standard deviation.

p > 0.05 = not significant; *p ≤ 0.05 = significant.

The nature of the middle-ear operation(s) in each group is shown in Tables 2 and 3. The cranial and general symptomatology features in the two groups are shown in Table 4, which reveals no significant difference in these symptoms between the two groups. However, the presence of at least two otoneurological symptoms (hearing loss, subjective tinnitus, and vertigo) was significantly higher in the group with temporalis fascia harvesting (50.7%) versus the group where the temporalis fascia was not harvested (24.3%), (p= 0.009).

Table 2. Nature of middle-ear operation(s) in patients having temporalis fascia harvesting

	Number (n = 67)	Percent
Unilateral temporalis fascia myringoplasty	36	53.7
Unilateral modified radical mastoidectomy for cholesteatoma	19	28.4
Unilateral recurrent temporalis fascia myringoplasty	4	6.0
Unilateral recurrent modified radical mastoidectomy for cholesteatoma	2	3.0
Unilateral cochlear implantation through suprameatal approach	2	3.0
Bilateral temporalis fascia myringoplasty	2	3.0
Bilateral modified radical mastoidectomy for cholesteatoma	2	3.0

Table 3. Nature of middle-ear operation(s) in patients not having temporalis fascia harvesting

	Number (n = 37)	Percent
Unilateral endoscopic cartilage myringoplasty	16	43.2
Unilateral cochlear implantation through posterior tympanotomy approach	14	37.8
Unilateral cortical mastoidectomy for mastoid abscess	2	5.4
Bilateral cochlear implantation through posterior tympanotomy approach	1	2.7
Unilateral stapedotomy for otosclerosis	1	2.7
Bilateral stapedotomy for otosclerosis	1	2.7
Unilateral posterior tympanotomy for repair of perilymph fistula	1	2.7
Unilateral glomus tumor excision	1	2.7

Table 4. Cranial and general symptomatology features in the studied groups

	Temporalis fascia harvesting (n = 67)	No temporalis fascia harvesting (n = 37)	p-value
Headache	39 (58.2%)	18 (48.6%)	0.348
Jaw pain	30 (44.8%)	10 (27.0%)	0.075
Facial pain	25 (37.3%)	10 (27.0%)	0.288
Neck pain	20 (29.9%)	6 (16.2%)	0.124
Bruxism	22 (32.8%)	10 (27.0%)	0.539
Impaired sleep pattern	20 (29.9%)	5 (13.5%)	0.062
Affective disorders	17 (25.4%)	6 (16.2%)	0.281

Data are expressed as number (%).

p > 0.05 = not significant.

The clinical examination findings in the TMJ(s) in the group that had temporalis fascia harvesting and the group that did not have harvesting of the temporalis fascia are shown in Tables 5 and 6, respectively. The total signs of clinically detectable internal derangement in the TMJ(s) was found in 79.1% of the former group, compared to only 29.7% of the latter group (p= 0.001). Additionally, 4 patients of the former group gave a previous history of open-lock, compared to none in the latter group.

Table 5. Clinical examination findings of the temporomandibular joint (TMJ) in patients having temporalis fascia harvesting

	Number (n = 67)	Percent
Bilateral disc displacement with reduction	38	56.7
Ipsilateral disc displacement with reduction	8	11.9
Ipsilateral degenerative joint disease	5	7.5
Disc displacement without reduction (closed-lock)	2	3.0
Total pathology	53	79.1%

Table 6. Clinical examination findings of the temporomandibular joint (TMJ) in patients not having temporalis fascia harvesting

	Number (n = 37)	Percent
Bilateral disc displacement with reduction	7	18.9
Ipsilateral disc displacement with reduction	3	8.1
Disc displacement without reduction (closed-lock)	1	2.7
Total pathology	11	29.7%

Discussion

The current study revealed evidence of internal derangement of the TMJ(s) in 79.1% of patients who had a previous middle-ear operation involving harvesting of temporalis fascia, compared to only 29.7% of patients who did not have harvesting of temporalis fascia during the surgery (p= 0.001). The incidence of internal derangement in the latter group was comparable with the incidence in general population studies [39]. In the cases examined, clicking in the TMJ(s) was most frequently bilateral. As the two TMJs cannot function independently during mandibular movements, internal derangement of one joint is usually associated with internal derangement of the other joint over a period of time [40,41]. This is due to abnormal non-physiological stresses on the other joint during mandibular movements [6].

During mandibular movements, especially on mastication, a delicate coordinated activity of various portions of the temporalis muscle, in conjunction with the activity of other masticatory muscles, is physiologically essential to prevent excessive TMJ loading [42,43]. The temporalis muscle is covered externally by the temporalis fascia, from which it gains a wide attachment [12,13]. The function of the temporalis fascia, as that of other fasciae and aponeuroses giving attachment to muscle fibers, is to store and rapidly release energy upon muscle contraction (myofascial force transmission). Myofascial force transmission is a complementary mode of force transmission, adding power to the direct muscle-to-tendon force transmission [44,45]. The integrity of the fascia covering the muscle has been found to enhance the efficiency of muscle contraction and improve force production [46]. Removal of the fascial covering of a muscle has a major effect on the functional characteristics of the contracting muscle [47]. Therefore, it is conceivable that harvesting of temporalis fascia would affect the contractile functions of the temporalis muscle. Studies on the temporalis muscle, as part of a lever system with the fulcrum at the TMJ, concluded that a dysfunctional temporalis muscle contraction was associated with a higher incidence of TMJ disorders [18,48]. Asymmetry and asynchrony of condylar movements, associated with abnormal temporalis muscle contractile function, would affect the loads acting on the TMJs, thereby putatively predisposing to disc displacement [9,49].

Under normal conditions, the articular disc and mandibular condyle move together as a functional complex during mandibular movements, due to the integrity of the joint ligaments [7]. Abnormal muscle forces acting on the TMJ(s) may lead to laxity of the joint ligaments, thereby predisposing to disc displacement [7]. Additionally, active muscular factors, (the disco-muscular apparatus) are involved in the stability of the disc-condyle complex during mandibular movements. The disco-muscular apparatus involves a balancing action between various muscle fibers attached to the anterior aspect of the disc, which act at different vectors. These include muscle fibers from the upper head of the lateral pterygoid and muscle fibers from the temporalis [14,15,31–33]. It has been postulated that an unbalanced activity of muscle fibers from the upper head of the lateral pterygoid contributes to the anteromedial displacement of the TMJ disc, which is the most common form of disc displacement [50,51]. This alteration in disc position could occur due to hypofunction of the temporalis muscle fibers attached to the disc, following harvesting of temporalis fascia. Indeed, arthroscopic division of the lateral pterygoid muscle fibers attached to the disc has recently been described as a novel treatment for advanced disc displacement [52].

Harvesting of temporalis fascia is associated with immediate postoperative pain, which may persist for 3 months or longer [25]. The cause of deep muscle pain may be related to myositis of the temporalis muscle or crushing of sensory nerve fibers, thereby activating muscle nociceptors [24,53]. The superficial temporalis muscle is heavily endowed with muscle spindles, and the temporalis fascia is rich in proprioceptors [54,55]. Alterations in proprioceptive signals from the temporalis muscle and temporalis fascia, following harvesting of temporalis fascia, may contribute to a loss of fine control of temporalis muscle movements associated with temporalis myofascial pain [17,55,56]. This may be manifested clinically as a reduced maximal bite force [57,58]. Recent studies have revealed that the temporalis muscle motor changes, in the presence of myofascial pain, are associated with central nervous system neuroplastic changes [59,60]. These changes may lead to a redistribution of activity within and between the muscles of mastication, including reduced agonist muscle activity and increased antagonist muscle activity [27]. These motor changes were found to persist even after resolution of the pain [61]. In relevance to harvesting of temporalis fascia, a recent MRI study revealed that a reduced temporalis fascia/aponeurosis to temporalis muscle volume was correlated to chronic TMD findings [62]. From the aforementioned studies, it can be postulated that temporalis muscle hypofunction, following harvesting of temporalis fascia, leads to uncoordinated movement of the mandible during mastication [63]. The abnormal biomechanical forces applied to the disc-condyle complex could alter the shape and function of the articular tissues, thereby predisposing to disc displacement and internal derangement [64].

Recent innovations in otologic surgery have caused a shift in the indications for harvesting of temporalis fascia [65]. Notably, temporalis fascia grafting of a perforated tympanic membrane is increasingly being replaced by endoscopic tragal cartilage myringoplasty, with excellent results and minimal morbidity [65,66]. Limited cholesteatomatous disease can now be excised using a transcanal endoscopic procedure, without resorting to open-cavity mastoidectomy and temporalis fascia grafting of the mastoid cavity and tympanic membrane [67]. On the other hand, the classic cortical mastoidectomy and posterior tympanotomy approach for cochlear implantation is increasingly being replaced by the suprameatal approach, which frequently requires temporalis fascia grafting of a traumatized tympanic membrane [68]. The latter approach avoids the serious risk of facial nerve injury during the posterior tympanotomy approach. The present paper represents a report of the relative incidence of internal derangement of the TMJ(s) in a constellation of otologic procedures involving the middle-ear cleft. The findings confirmed a higher incidence of internal derangement of the TMJ(s) in patients who had temporalis fascia harvesting compared to those who did not have harvesting of temporalis fascia.

Disc displacement of the TMJ is of special relevance to the otologist because it may be associated with otoneurological symptoms, including hearing loss/ blocked ear sensation, tinnitus, and vertigo (Costen’s syndrome) [69]. The etiology of these symptoms is attributed to tension exerted by the displaced disc on its ligamentous attachments to the malleus of the middle ear [70,71]. This tension would cause an increased stiffness of the middle-ear system and altered position of the stapes [72]. The altered position of the stapes at the oval window would cause altered firing rate patterns in the hair cells of the cochlea and the vestibule in the inner ear [73]. The altered input from the inner ear, in patients with TMJ internal derangement, is modulated by central nervous system neuroplastic changes [74,75]. Previous studies revealed that hearing loss, subjective tinnitus, and vertigo developed in 25%, 32%, and 56% of TMJ disorder patients, respectively [76,77]. In the current study, at least two otoneurological symptoms were present in 50.7% of patients who had the temporalis fascia harvested, compared to 24.3% of those who had ear operations without harvesting of temporalis fascia (p= 0.009). This finding reflects the increased morbidity in patients who had temporalis fascia harvesting, regarding otoneurological symptoms.

Limitations

One limitation of the current study was that it was an unblinded study, conducted by a single author, the aim of which was to investigate the effect of harvesting of temporalis fascia on TMJ function. A further limitation was that it was a purely clinical study. Future studies should involve jaw-tracking systems to determine the effect of harvesting of temporalis fascia on mandibular kinematics. Additionally, MRI studies can reveal the anatomy of the TMJ structures before and after the operation. The value of the current study was that it raised a previously uninvestigated issue regarding the effect of harvesting of temporalis fascia on mandibular kinematics and TMJ pathology. If the results of this study could be further validated in future studies, the choice of surgical approach for middle-ear disorders could be modified, e.g., by using totally endoscopic approaches for middle-ear surgery.

Conclusion

Harvesting of temporalis fascia probably alters mandibular kinematics and predisposes to internal derangement of the TMJ(s). A choice of a surgical operation on the middle ear not involving harvesting of temporalis fascia would cause less morbidity to the patient.

Disclosure statement

There is no conflict of interest.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.