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| ORIGINAL ARTICLE |
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Year : 2012? |? Volume : 1? |? Issue : 2? |? Page : 88-94 |
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Temporomandibular joint mobility in adult females with Ehlers-Danlos syndrome, hypermobility type (also known as joint hypermobility syndrome)
Andrea Ancillao1, Manuela Galli1, Claudia Celletti2, Marco Castori3, Giorgio Albertini4, Filippo Camerota2
1?Department of Bioengineering, Politecnico di Milano, Milano; Department of Paediatric Rehabilitation, IRCCS San Raffaele Pisana, Roma, Italy
2?Physical Medicine and Rehabilitation Division, Umberto I Hospital, Roma, Italy
3?Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Roma, Italy
4?Department of Paediatric Rehabilitation, IRCCS San Raffaele Pisana, Roma, Italy
| Date of Submission |
29-Nov-2012 |
| Date of Acceptance |
30-Nov-2012 |
| Date of Web Publication |
8-Jan-2013 |
Correspondence Address:
Andrea Ancillao
Department of Bioengineering, Politecnico di Milano, p.zza Leonardo Da Vinci 32, 20133, Milano
Italy
DOI: 10.4103/2278-9588.105697
Context: It is well-known that subjects affected by Ehlers-Danlos Syndrome (EDS), hypermobility type/Joint Hypermobility Syndrome are characterized by severe joint hypermobility with recurrent joint dislocations and chronic pain and biomechanical dysfunction of the temporo-mandibular joint (TMJ).
Aims: The study aims to measure TMJ mobility in EDS subjects to quantitatively characterize the TMJ dislocation during specific tasks as well as head adjustments, already documented by literature by observational techniques.
Materials and Methods: Female EDS subjects and age matched controls were asked to perform simple opening-closing movements of the mandible. Kinematics data was recorded and analyzed through an optoelectronic motion capture system. Some parameters of the motion were studied: range of motion of the condyles, range of motion of the chin, aperture angle, movement speed, and frequency.
Statistical Analysis Used: The statistical t-test was used to compare results from pathological group to the control group.
Results: Significant differences, between EDS group and controls, were found for the backward rotation of the head, lateral range of motion of the chin, frequency, and velocity. Results were in accordance with the clinical observations. The results not only confirmed that EDS subjects back-rotate the head while performing the opening-closing task but also quantified the entity of this behavior.
Conclusions: The method we proposed is noninvasive and is able to analyze mandible kinematics. It may be used by clinicians to assess the healthy status of TMJ, to quantify mobility, and hypermobility of the mandible and to help diagnosis of TMJ dysfunctions.
Keywords:?Ehlers-Danlos syndrome, hypermobility, mandible, motion analysis, temporomandibular joint
How to cite this article:
Ancillao A, Galli M, Celletti C, Castori M, Albertini G, Camerota F. Temporomandibular joint mobility in adult females with Ehlers-Danlos syndrome, hypermobility type (also known as joint hypermobility syndrome). J Cranio Max Dis 2012;1:88-94 |
How to cite this URL:
Ancillao A, Galli M, Celletti C, Castori M, Albertini G, Camerota F. Temporomandibular joint mobility in adult females with Ehlers-Danlos syndrome, hypermobility type (also known as joint hypermobility syndrome). J Cranio Max Dis [serial online] 2012 [cited?2013 Aug 27];1:88-94. Available from:?https://craniomaxillary.com/text.asp?2012/1/2/88/105697 |
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??Introduction |
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Joint hypermobility (JHM) implies a range of joint movement that exceeds what is considered to be normal for that joint taking into consideration the individual's age, gender, and ethnic background. [1] JHM is a common finding in population with a prevalence between 10% and 30%. [2] The prerequisite of JHM is a generalized ligamentous laxity that may be found in a substantial proportion of healthy individuals, the majority of whom probably does not suffer effects. [3]
The JHM becomes joint hypermobility syndrome (JHS) when it leads to musculoskeletal symptoms. [1] JHS is one of the heritable disorders of connective tissue that have in common the generalized joint laxity. [4]
JHS is probably, among the connective disorders, the most common, and is often overlooked. [2] Recently, it has been shown that JHS is closely related to the ?Ehlers-Danlos syndrome?More Details hypermobility type (EDS-HT). [5]
Severe JHM with recurrent joint dislocations and chronic moderate-to-severe pain are the most frequent and severe complaints, associated with muscle cramps, tendonitis, headache and fatigue, often reported among EDS-HT/JHS patients. [6],[7]
JHM is also considered a risk factor for temporomandibular joint (TMJ) disorders. [8] Since constitutional hypermobility can affect all joints, which would include the TMJ, a correlation exists between JHM and temporomandibular dysfunction (TMD) and is shown by different studies. [8],[9],[10]
It is also well-known that the stomatognathic system, a functional unit characterized by skeletal components, dental arches, soft tissue, the TMJ, and masticatory muscles plays an important role in head movements control. [11]
Measurement of mandible motion
Some protocols for the measurement of mandible and facial motion were proposed in the literature. Vimercati et al. [12] proposed a marker protocol to capture and quantitatively analyze facial expressions and kinematics through an optoelectronic system. This protocol proved to be useful to characterize the resting position, facial, and speaking movements, for example, lips motion while pronouncing words or smiling. However, this protocol was poor on analyzing mandible-specific kinematics, because it did not provide enough markers on the mandible.
A specific protocol to analyze mandible movements was proposed by Mapelli et al. [13] They put a 3-markers cluster on the mandible connected to the lower interincisal point through an extra-oral antenna directly connected to the teeth. This protocol was good to fully record and study mandible movements but was invasive for the subject as it requires the extra-oral antenna installation.
Therefore, the authors of this work decided to define a new less-invasive marker protocol, which would allow to study in detail the mobility of the mandible related to specific tasks performed by pathological subjects.
Aims of the study
The study aims to examine the effect of EDS-HT/JHS hypermobility on the motion and mobility of the mandible in female patients affected by this pathology. Head movements while moving the TMJ were also investigated.
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??Materials and Methods |
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Subjects
Two groups of subjects were enrolled for this study. Pathological group was composed of 20 female subjects affected by EDS-HT/JHS. Mean age was 35.5 years, with a SD of 14 years and range 16-61 years.
EDS-HT/JHS patients were selected from those attending a multidisciplinary service dedicated to hereditary connective tissue disorders (HCTDs) and sent to the "joint hypermobility" outpatient clinic in the Division of Physical Medicine and Rehabilitation of the Umberto I University Hospital (Rome, Italy) and the clinical genetics outpatient clinic at the Medical Genetics of the San Camillo-Forlanini Hospital (Rome, Italy). After excluding other connective disorders, diagnosis was based on published diagnostic criteria including the Brighton criteria for JHS [14] and the Villefranche criteria for EDS-HT. [15] Patients were included if they met at least one of these two criteria.
JHM was assessed by applying the Beighton score. [6] The Beighton score is a 9-point evaluation with attribution of one point in presence of any of the following features: (a) passive apposition of the thumb to the flexor aspect of the forearm (one point for each hand), (b) passive dorsiflexion of the V finger beyond 90? (one point for each hand), (c) hyperextension of the elbow beyond 10? (one point for each arm), (d) hyperextension of the knee beyond 10? (one point for each leg), and (e) forward flexion of the trunk with the knees extended and the palms resting flat on the floor.
The control group was composed of 15 healthy female subjects. Control subjects had an average age of 35 years, with a SD of 8.75 years and range 24-47 years. Each subject was examined by a physiatrist prior to the trial and they were included in the control group only if they did not present JHM or any problem related to the TMJ, any disease related to posture and postural control, and they presented a normal ligament stiffness and a general healthy status.
Equipment
All the measurements were performed in the Motion Analysis Laboratory of IRCCS San Raffaele Pisana, Roma, Italy.
A motion capture optoelectronic system (BTS Smart, BTS Italy s.p.a.), which allows the recording of 3D x, y, z coordinates of the markers and reproduce them in a 3D virtual space, was used. The optoelectronic system had six infrared cameras that worked at a sampling frequency of 200 Hz.
Before every data acquisition, a calibration was performed. The calibrated volume was about (60 ? 60 ? 60 cm) and was defined considering that the volume has to include the whole motion and it has to be as small as possible, in order to obtain a high accuracy.
Marker protocol
To record the motion of the mandible, and also the motion of the head in respect to the trunk, 12 spherical and hemispherical markers were placed over the skin of the subject.
Landmarks on the face were chosen according to the protocol proposed by Mapelli et al. [13] for the analysis of the mandible movements. Some markers were added or replaced allowing the recording of head movements.
The chosen marker protocol is defined as follows [Figure 1]:
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Figure 1: Marker setup for head and mandible motion analysis. The reference system identifies the movement directions: x: Medio-lateral, y: Anterior-posterior, z: Vertical
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Three markers (5 mm diameter) on the head, a three markers cluster (3 mm diameter) on the chin, two markers (3 mm) on the condyles, one marker (3 mm) on the glabella.
These were also placed: One marker (5 mm) for each shoulder (on the acromion) and one marker (5 mm) on the stern.
Markers were labeled according to [Figure 1].
The three markers cluster on the chin were allowed to build a local reference system (LRS) for the mandible minimizing the slipping effect of the skin over the underlying bone.
The markers on the condyles and on the glabella were allowed to measure the position of the respective landmarks.
The three markers groups on the head and on the trunk were allowed to compute a LRS for the respective anatomical district.
Every LRS was built in order to have the z-axis facing upwards and the y-axis pointing to the right of the subject. The LRSs were centered, respectively, in c head, m3, and stern.
Trial acquisition and processing
Each subject sat on a stool in the calibrated volume and was asked to keep a natural and relaxed posture while performing the motor tasks.
The following trials were acquired:
- Static trial: The subjects were asked to remain motionless, with the mouth closed, for nearly 5 seconds.
- Dynamic trial 1: The subjects were asked to open and close the mouth three times reaching the maximum aperture.
- Dynamic trial 2: The subjects were asked to open and close the mouth quickly for about 10 times, as they were chewing.
By processing the static trial, the position of the condyles was estimated in the LRS of the mandible.
In addition, the offset angle of the mandible, between glab and m3 with center in the midpoint between condyles, was computed. This angle corresponded to the closed mouth condition.
To estimate the position of the condyle, while the mandible is moving, the marker applied over the skin is not reliable, due to the skin slipping over the bone. Therefore, in the dynamic trials, the condyle positions needs to be estimated by reconstructing a virtual marker with respect to a LRS associated to the mandible. This can provide a good approximation of condyle three dimensional kinematics. [13]
The virtual markers for the condyle positions were reconstructed as follows (all steps and computations were made by using BTS Smart Analyzer Software, BTS Italy s.p.a.):
- By processing the static trial, a LRS for the mandible was built by using the 3-markers cluster on the chin.
- The absolute coordinates of the markers applied over the condyles during the static trial were referenced to the LRS.
- In the dynamic trials a LRS for the mandible was built in the same way as for the static trial (step 1).
- In each dynamic trial, virtual markers for the condyles were constructed by using the LRS and the relative coordinates of condyles found in step 2.
- Virtual markers found in step 4 were processed in order to study condyle movements.
After reconstructing the condyle position, the dynamic trial where then processed using BTS Smart-Analyzer software in order to extract the following parameters:
Dynamic trial 1:
- Range of motion (RoM) of the right condyle (over x, y, and z directions).
- RoM of the left condyle (over x, y, and z directions).
- RoM of the chin (over x, y, and z directions).
- Max mandibular opening angle.
- Max backward rotation of the head.
Dynamic trial 2:
- Time required to complete the task.
- Frequency (complete opening-closing cycles per second).
- Mean velocity of the chin.
- Standard deviation (SD) of velocity.
- Max velocity.
In order to compute RoM, 3D coordinates of the markers were measured and the difference between the maximum and minimum position, reached by the markers, was computed.
Backward rotation of the head was measured as the angle variation between the LRS built for the head and the LRS built for the shoulders. Rotation vas considered over the sagittal plane (around the medio-lateral axis).
Opening angle and backward rotation were measured for the three apertures and then averaged over the three apertures.
Ratio between right and left RoM (R/L) was also computed in order to quantify asymmetry in the movement.
The ratio was defined as:
where,  represents the absolute value.
The closer is the R/L ratio to 0, the more the movement is symmetrical. As the R/L value increases, the motion becomes asymmetrical.
For the open-close 10 times trials, the total time was measured from the beginning of the first movement to the end of the last movement. The effective number of opening and closings was measured and frequency was obtained by dividing this number to the total time elapsed.
Velocity was measured as first order derivative of the trajectory. Proper smoothing filter was applied before deriving the signal (built-in smoothing filter by SMART Analyzer, BTS Italy).
Data was collected for each subject and tabulated in order to compare overall results from pathological group and control group. Mean value, SD and coefficient of variation (CV) were computed for each parameter and for each group.
Data was also tested to check if samples did fit a normal distribution. Since this condition occurred, the t-test was run, for each parameter, to see if there were statistically significant differences between pathological group and control group. Differences were considered significant if P < 0.05.
Protocol validation
The results of vertical displacement of the chin, mandibular opening angle and condylar RoM, which we obtained from our control group, were compared with the results by Mapelli et al. [13] who studied the movements of the mandible during mouth opening and closing, making comparisons between healthy male and female subjects.
Study approval
This study was approved by the Institutional Scientific Board of IRCSS San Raffaele Pisana, Roma, Italy. The subjects were informed and signed consent to use their data for research purposes.
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??Results |
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The results for control group were in accordance with the results obtained by Mapelli et al. [13] for female normal subjects. Their results are summarized and compared with the results of this study in [Table 1].
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Table 1: Comparison of our results with the results obtained by Mapelli et al.[13] for female normal subjects. Since we had two values of RoMs, the reported value is the average between right and left RoM
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The mean values found for each parameter and each group are shown in [Table 2].
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Table 2: Comparison of mandible parameters between Ehlers-Danlos syndrome hypermobility type/joint hypermobility syndrome group and Control for open-close three times trials. Average is the average value between subjects. Coefficient of variation is the coefficient of variation
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As shown in [Table 2], there were no significant differences between EDS-HT/JHS subjects and control for condyle RoM. Also for chin displacements, in terms of vertical and anterior-posterior RoM and in terms of mandible opening angle, there were no statistically significant differences.
Significant differences were found for the backward head rotation (P = 0.0003) and lateral RoM (P = 0.0128). Average backward rotation of the head was 7.0? for EDS-HT/JHS and 2.9? for control with CV of nearly 0.5? for both [Table 2].
[Figure 2] and [Figure 3] show sample results of the backward head inclination correlated with the mandible opening angle, respectively, for a EDS subject and a control subject.
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Figure 2: Sample plot of the the mandibular opening angle (first row) and of backward head rotation (second row) of a EDS-HT/JHS subject opening and closing three times the mouth
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Figure 3: Sample plot of the the mandibular opening angle (first row) and of backward head rotation (second row) of a control subject opening and closing three times the mouth
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There were also significant differences in the R/L ratio for medio-lateral and anterior-posterior directions, showing an accentuated asymmetry in Ehlers-Danlos subjects.
Other significant differences were found in the total time required to complete the opening-closing task (P = 0.0018) and therefore in the frequency of the movement (P = 0.0003). In addition, mean velocity was significantly lower for EDS-HT/JHS (0.068 m/s) than control (0.107 m/s) with P = 0.0242. Detailed results are shown in [Table 3].
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Table 3: Comparison of mandible parameters between Ehlers-Danlos syndrome hypermobility type/Joint hypermobility syndrome group and control for open-close 10 times trials. Average is the average value between subjects. Coefficient of variation is the coefficient of variation
Click here to view
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??Discussion and Conclusion |
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This study showed that EDS-HT/JHS subjects have a different mobility of the mandible than the control group. They also have a poor control and poor stability of the mandible while opening and closing. This conclusion is enforced by the medio-lateral RoM of the chin that in EDS-HT/JHS group resulted higher than controls. Moreover, the ratio between right and left RoMs of the condyles, that was higher in EDS-HT/JHS group, suggested a significant asymmetry in the mandible movement for EDS-HT/JHS subjects.
It is known that patients with EDS-HT/JHS have an impairment of joint proprioceptive acuity, observed, for example, for the finger and the knee joints. [16],[17] The particular anatomic location of the mandible bone and its relationship with the cervical spine, may predispose this structure to a proprioception impairment. The muscles of mastication and articulation of the mandible, as well as head positioning, play an important role in postural balance and control. In fact, the mesencephalic nucleus of trigeminal nerve receives proprioceptive inputs from this muscle and processes this information through the trigeminal nerve. The reduced proprioception of the TMJs may be a determinant in the asymmetry of the movement, associated to ligament laxity and joint instability. Impaired joint proprioception may create a neuromuscular imbalance that may involve the cervical spine, that is, intimately related to the cranium and the masticatory system.
A coordinated action between mandibular elevation and depression was associated to movements of the head and neck. [18] This coordinating action appears to be due to anticipatory control mechanisms, which are common for the neuromuscular system of the jaw and the neck. [19] In fact, the anterior and posterior cervical muscles are responsible of the control of the head position. [20] Disharmonies of the neuromuscular system may therefore lead to instability of the head position. This instability was observed in our patients as a backward head rotation significantly higher than in control group.
The results confirmed the clinical observation about the EDS influencing ligament stiffness and TMJ in particular. The results also confirmed that EDS-HT/JHS subjects back-rotate the head while performing the opening-closing task.
The method we proposed is noninvasive and is able to analyze mandible kinematics. It may be used by clinicians to assess the healthy status of TMJ, to quantify mobility and hypermobility of the mandible and to help diagnosis of TMJ dysfunctions.
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? [Figure 1], [Figure 2], [Figure 3]
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? [Table 1], [Table 2], [Table 3]
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