Assessment of Discectomy and Eminectomy for Temporomandibular Joint Derangement: Manitoba

Experience

Bachelor of Science in Dentistry (B.Sc. Dent) Thesis

By:

Harmeet Manghera

B.Sc. Dent

2019

Supervisors:

Dr. Reda F. Elgazzar and Dr. Adnan Shah

Dental Diagnostic and Surgical Sciences

Oral and Maxillofacial Surgery

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS …….……...…………………………………………………..….… 3

ABSTRACT …………………………………………………………………………………..…..4

INTRODUCTION …………………………………….………………………………………….5

PATIENTS AND METHODS………………………………………………...………………….7

RESULTS………………………………………………………………………..……………......9

DISCUSSION…………………………………………………………………………...……….13

CONCLUSION…………………………………………………………………….…………….17

REFERENCES…………………………………………………………………………………. 18

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Acknowledgements I wish to express my sincere gratitude towards my mentors Dr. Elgazzar and Dr. Shah, in the department of DDSS/OMFS, for their encouragement and supervision during this project. I am also grateful to Dr. Bhullar, the Associate Dean of Research, for running the BSc (Dent) Program through the Faculty of Dentistry, University of Manitoba. This project was partially supported by the Canadian Association of Oral and Maxillofacial Surgeons. HSC and SOGH Health Records personnel provided the resources needed to complete this thesis. It would not have been possible without their help. I am thankful for my parents for providing moral support and encouragement along the journey.

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Abstract

Temporomandibular joint disorder (TMD) is caused by the loss of function of the intra-

articular tissues, leading to a failure in the biomechanics of the joint. Non-surgical modalities and

less invasive surgical procedures such as arthroscopy are usually employed to manage patients

with TMD in their earlier stages of the disease. Many patients respond well to such modalities

while others fail to show satisfactory improvement. Hence, they qualify to be treated with more

invasive open joint surgery such as arthroplasty. The aim of this study was to assess the surgical

outcomes of temporomandibular joint (TMJ) arthroplasty, discectomy and eminectomy for the

management of the refractory TMD cases. The retrospective chart review was conducted on TMD

patients who were diagnosed and treated with arthroplasty, eminectomy and discectomy at the

Health Sciences Centre (HSC) and the Seven Oaks General Hospital (SOGH) between the years

of 2011 and 2017. The University of Manitoba Research Ethics Board (REB) provided approval

for the project. A data capture sheet was created for data collection. Pre-operative, intra-operative

and post-operative information was recorded. Eight (22%) males and 28 (78%) females

incorporated the study group with ages ranging from 17 to 68 years with a mean of 40.4 years. The

follow up period ranged from 1 to 29 months with a mean of 8.6 months. All patients had adequate

recovery after receiving the arthroplasty supplemented with post-operative physiotherapy.

Majority of these patients showed a noticeable increase in the range of jaw motion and a reduction

in pain. No major complications were reported, a few minor complications were observed

including numbness of the ear, transient weakness of the surrounding muscles due to impingement

or stretching of the facial nerve and minor scar formation on the skin. The results show that TMJ

arthroplasty is an effective and definitive surgery for the treatment of refractory TMD.

Key Words: TMJ Internal Derangement, TMD, TMJ Arthroplasty, Discectomy, Eminectomy

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Introduction

Temporomandibular Joint Disorder (TMD) is used to define pain/dysfunction due to

abnormalities in the TMJ, masticatory muscles and all supporting structures. Although a

standardized treatment does not exist, alleviating pain and improving function of the

temporomandibular joint through a conservative approach is the main goal when treating TMD. It

is for this reason that open joint surgery is usually a last resort when attempting to save the TMJ.

It was found that nearly 5-33% of the general population show subjective symptoms of TMD

between the age of 20-40.1

A disc is situated between the condyle and articular eminence, which allows for smooth

motions when opening and closing. Complications arise when the disc becomes displaced

preventing lateral and protrusive movements and limiting the maximal opening of the jaw.2

Various treatment options exist ranging from simple medical treatments to complex surgeries.

When medical techniques such as patient education, physiotherapy, behavioural stress

management, occlusal adjustment or splint therapy fail, surgical intervention is indicated.

Arthroscopy and arthrocentesis are two examples of minimally invasive techniques that show high

success rates in various studies.

Several studies in the past indicated that arthroscopic lysis and lavage in closed lock

patients showed success rates in approximately 80-86% of all patients.3 Arthrocentesis and

arthroscopy is used in fewer than 10% of patients that present with TMD. Of this 10%, arthroscopy

is capable of removing symptoms in 70-86% of the cases, with only 10% of this group requiring

open joint surgery.4

Arthroplasty involves the surgical approach to the TMJ structures via an incision in the

skin, called the preauricular incision.5 Eminectomy or eminoplasty involves partial or total

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removal of the anterior articular eminence using surgical bur and bone files; discectomy involves

the elimination of all mechanical interferences within the joint caused by TMJ meniscus and is

indicated in more severe cases.6

To replace the disc, grafts and alloplastic materials such as silicone, dermis, cartilage and

myofascial grafts have been used in the past with unacceptable complications. It is argued that disc

replacement isn’t necessary following discectomy.7 Teflon-Proplast and most grafts proved to

show little success in the past few decades, leading to the investigation of abdominal fat grafts

versus temporalis myofascial flap, in hopes of finding a more effective material. Problems exist

with abdominal fat grafts as they degrade over time due to a lack of vascularization.

Discectomy shows better results compared to eminectomy regardless of whether it is

performed with the inclusion of an abdominal fat graft. The abdominal fat graft provides evidence

of cushioning the condyle within the articular but shows contradicting evidence when compared

to the temporalis myofascial flap graft.7 There is no perfect solution to treating temporomandibular

joint disorder as the pain and/or dysfunction due to abnormalities in the temporomandibular joint,

masticatory muscles and all supporting structures can be treated in a variety of effective ways.5,7

New methods continue to be studied and tested in alleviating pain and improving the function of

the TMJ.

Aim of the Study:

The purpose of this study was to determine the effectiveness of arthroplasty, eminectomy and

discectomy in the treatment of TMD patients in Manitoba.

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Patients and Methods

The retrospective chart review was conducted on TMD patients who were diagnosed both

clinically and through MRI with arthroplasty, eminectomy and discectomy at the Health Sciences

Centre (HSC) and the Seven Oaks General Hospital (SOGH) between the years of 2011 and 2017.

The University of Manitoba Research Ethics Board (REB) provided approval for the project. This

study was conducted in order to determine whether or not arthroplasty including discectomy and

eminectomy is an effective surgery to alleviate pain and various other symptoms associated with

TMD. The age, gender and occupation of each individual patient were recorded. The clinical

examination recorded symptoms of pain and the ranges of motion. While the MRI results were

recorded specific to each side of the TMJ as normal, anterior disc displacement with or without

reduction, or osteoarthritis.

Exclusion criteria were applied to subjects who had missing information concerning their

clinical examination, MRI results or the etiology of their TMD. Eight males and 28 females made

up the study group with ages ranging from 17 to 68 years with a mean of 40.4 years. After a follow

up period, a clinical examination was once again conducted, where symptoms of pain, as well as

the ranges of motion were reassessed. The follow up period ranged from 1 to 29 months with a

mean of 8.6 months. Internal derangement was recorded for the left and right sides of the TMJ

using the Wilkes Classification System2 (Table 1). A grade of I-V was given for each patient.

A data capture sheet (Figure 1) was formed with patient, pre-operative, intra-operative and

post-operative information. To ensure the patients remained anonymous, each patient was

designated a unique code number, with a master key to identify patients if needed. In order to assist

with the coding, the initials of each patient as well as their age and gender were recorded. Data

were analysed using MiniTab18.

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Table 1. Wilkes Staging of Internal Derangement of TMJ.7

Stage Clinical Imaging I. Painless clicking

No restricted motion Slightly forward disc, reducing Normal osseous contours

II. Occasional painful clicking Intermittent locking Headaches

Slightly forward disc, reducing Early disc deformity Normal osseous contours

III. Frequent pain, Joint tenderness, Headaches, Locking, Restricted motion Painful chewing

Anterior disc displacement, reducing early progressing to non-reducing late Moderate to marked disc thickening Normal osseous contours

IV. Chronic pain, headache Restricted motion

Anterior disc displacement, non-reducing Marked disc thickening, abnormal bone contours

V. Variable pain Joint crepitus Painful function

Anterior disc displacement, non-reducing with perforation and gross disc deformity Degenerative osseous changes

Figure 1. Data Capture Sheet

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Results A total of 36 patients were studied who received arthroplasty with eminectomy and/or

discectomy at SOGH or HSC between the years of 2011-2017. Eight (22%) males and 28 (78%)

females made up the study group. The median age for TMD progression due to microtrauma,

macrotrauma and unknown reasons was 26, 40 and 54, respectively. Most patients reporting with

TMD due to macrotrauma were due to the result of a motor vehicle accident.

Pre and post-operative findings during the clinical examination were compared. Bruxism

and clenching were only included for statistical purposes as surgical treatment would have no

effect on a behaviour. Pre-operatively, almost all patients presented with TMJ pain. The number

of patients presenting with symptoms pre-operatively including TMJ pain, muscle pain, clicking

and trigger point were 35 (97.2%), 25 (69.4%), 21 (58.3%), and 5 (13.9%), respectively.

Immediate post-operative results showed a remarkable improvement in most patients. The post-

operative findings during the last follow-up appointment for TMJ pain, muscle pain, clicking and

trigger point were 19 (52.8%), 12 (33.3%), 10 (27.8%) and 1 (2.8%), respectively (Figure 2).

Figure 2. Pre-Operative vs Post-Operative frequency of assorted symptoms.

05

10152025303540

TMJ Pain Muscle Pain Clicking TriggerPoint

Bruxism Clenching

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Various patients had received some form of treatment for TMD previously. These

treatment options included medical or surgical treatment, with one patient receiving only medical

treatment, 13 receiving only surgical treatment and 14 receiving both. A comparison was

completed regarding post-operative interincisal distance without pain (IIDWOP) with a previous

history of surgical treatment. Although the numbers were found to be statistically insignificant

(P>0.05), important information can be extracted from the data. When comparing IIDWOP with

previous surgical treatment, it was found that fewer arthroscopic surgeries correlated with an

increased IIDWOP measurement (Figure 3).

Figure 3. Comparison of median interincisal distance without pain with the number of previous arthroscopic surgeries determined by Kruskal-Wallis test.

Of the 36 cases, two were bilateral surgical cases resulting in a total of 38 joints treated. 6

(15.8%) were diagnosed as anterior disc displacement with reduction (ADDWR), 31 (81.6%) were

diagnosed as anterior disc displacement without reduction (ADDWOR), and 1 (2.6%) had a normal

disc position. Furthermore, of the 31 diagnosed with ADDWR, 18 (47.4%) were diagnosed with

Wilkes Stage IV, and 13 (34.2%) with Wilkes Stage V (Figure 4).

47.5

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Arthroscopy x 1 Arthroscopy x 2

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When comparing the etiology of the TMD with those diagnosed with ADDWOR, 61.2%

of cases were caused by macrotrauma, 22.6% were caused by microtrauma and 16.1% were caused

by unknown reasons.

Figure 4. T1 MRI comparing anterior disc displacement with and without reduction.

Patient were asked to score their perceived pain on a scale of 0-10 with 0 meaning no pain,

one to three meaning mild pain, four to seven meaning moderate pain and eight to ten meaning

severe pain. The pre-operative mean magnitude of pain was 6.5. In contrast to the post-operative

mean of 1.5, the pre-operative magnitude was significantly larger. Despite having non-parametric

values, the median was not used for this calculation, due to many of the patients reporting no pain

post-operatively. If the median had been used, it would have resulted in a post-operative median

magnitude of zero.

Different combinations of surgical procedures yielded varying results for inter-incisal

distance (IID), left lateral excursion (LLE), right lateral excursion (RLE) and protrusion.

Eminectomy alone was excluded from this analysis due to only one case being available for

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evaluation. The median IID for eminectomy and discectomy, discectomy alone, and discectomy,

eminectomy and condyloplasty were 34.5mm, 35mm and 37.5mm, respectively. Although the

results were found to be statistically insignificant (P>0.05), from a professional standpoint,

discectomy alone was found to provide the weakest results. An increased patient pool would allow

for more accurate results (Figure 5).

Figure 5. Comparison of surgical procedure combinations with the median post-operative ranges of motion determined by Mood Median test.

IID m

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The median pre-operative inter-incisal distance with pain (IIDWP), IIDWOP, RLE, LLE

and Protrusion were 25mm, 20mm, 3mm, 3mm and 2mm respectively. After comparing these

numbers with the post-operative results, a significant (P<0.05) improvement was noted in all five

of the categories (Table 2). The IIDWOP showed the highest numerical increase with a 15mm

improvement. However, the right and left excursions and protrusion showed nearly a 100%

increase in the range of motion as each post-operative recording was nearly twice that of the pre-

operative range.

Discussion

The purpose of this study was to determine the effectiveness of arthroplasty, eminectomy

and discectomy in the treatment of TMD through the assessment of inter-incisal distance, pain

scores and various other factors. When arthroscopy and arthrocentesis fail to alleviate pain or

increase the range of motion, an escalation must be made to a more invasive surgery. Arthroplasty

has shown to play an imperative role in decreasing TMJ pain in cases where there is anterior disc

displacement with chronic locking and arthritic changes.11-15

Several studies confirm that TMD is more prevalent in women than men, with

approximately 80% of those diagnosed with TMD being women.16 Although the reason is

Table 2. Pre-Operative vs Post-Operative Median Range of Motion determined by Mann-Whitney test.

Pre-Operative Median (mm) Post-Operative Median (mm) P Value

IIDWP 25 30 0.0221

IIDWOP 20 35 0.0063

LLE 3 6 0.0016

RLE 3 5 0.0060

Protrusion 2 3.5 0.0154

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unknown, it is hypothesized that women are more likely to report pain than men, resulting in the

perceived increased frequency. Variation in stress response and hormones may also play a role.16,17

In our study of 36 patients, 28 (78%) were female and 8 (22%) were male, which closely correlate

these studies.

When comparing different surgical combinations with post-operative ranges of motion, the

data were found to be statistically insignificant (P>0.05) due to the limited patient pool. Typically,

eminectomy is performed in earlier stages of TMD, while discectomy is performed in later stages.2

Although these findings were not statistically significant, from a professional point of view, it is

noted that discectomy and eminectomy show the best results when performed together, and the

weakest results when performed separately (Figure 6).

Figure 6. Showing preauricular, modified Bramley-Al Kayat flap for left TMJ arthroplasty (arrows): patient prep and draping (a); flap planning (b); dissection (c); upper joint space exposing the articular eminence (d); eminectomy (e); temporo-myofascial flap (f).

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Within this study, we observed a 15mm increase in IIDWOP and a 5mm increase in IIDWP

(P<0.05). Left and right lateral excursions and protrusion also had a statistically significant

increase in the range of motion. Patients who concluded the surgery with no reported pain had a

considerably larger increase in the inter-incisal distance than those with pain. This observation

may stem from the fact that patients with less severe symptoms tend to have a better recovery. A

study completed by Holmund et al. (2013) on chronic closed lock patients reported an 8mm

increase in inter-incisal opening and a 2mm increase in protrusive movements; a 2mm and 1mm

increase were also noted for the right and left lateral excursions, respectively.11 All measurements

were statistically significant and follow a similar trend to those found in our study.

In the Holmund et al. (2013) study, it was found that patients who underwent multiple

failed arthroscopies prior to the arthroplasty, had worse results in comparison to those who did

not.11 In our study, there was a similar trend when comparing patients who underwent arthroscopy

once, compared to those that received it twice, as those receiving it once had a larger inter-incisal

distance than the latter.

Holmund et al. (2013) also compared pre-operative and post-operative pain levels

measured on a scale of 0-10. The chronic closed lock patient group had a decreased pain score of

6.9 to 1.8 (P<0.05).11 These numbers are comparable to those from our study, which observed a

decrease in pain from 6.5 to 1.5. These numbers show that arthroplasty was associated with nearly

a 50% decrease in pain. When reviewing charts, often when TMJ pain was mentioned, there was

a lack of information regarding whether or not muscle pain was present in the area. There is

potential that patients experienced referred pain to their TMJ as a result of macrotrauma. Pain was

not always measured on a scale of 0-10, as descriptive words were sometimes used. This resulted

in certain omissions from our data. In order to gain more precise results in the future, a scale should

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be created within the hospital notes indicating both pre-op and post-op pain during each of the

follow up appointments.

Comparing follow-up periods, the study by Holmund et al. (2013) had a range of 6-17

months with an average of 9 months, while this study had a range of 1-29 months with an average

of 8.6 months. The mean age of the patients in this study was 40.4 years comparable to the 41

years in the 2013 study.11 Although follow-up times are comparable to those completed in other

studies, the limited period leads to unknown knowledge of the true extent of improvement. For

this reason, the patients lacked adequate follow-up time. In future studies, it would be necessary

to have increased follow-up appointments spanning roughly two years. The reason for a lack of

adequate follow up time may be due to patients accepting their condition. It is also likely that some

patients may have felt that due to a decrease or complete resolution in pain, a follow-up

appointment was not necessary. Other reasons include a lack of patient compliance or access to

HSC or SOGH for patients living in rural Manitoba.

In a study conducted by Miloro et al. (2017), the mean increase in maximal incisal distance

was approximately 10mm.14 These results closely match those completed within this study;

although lateral excursions and protrusion values were not mentioned. Comparing follow-up

periods, the 2017 study had a range of 2-48 months with an average of 11.8 months. The mean age

of the study was 35.1 years. Both this study and Miloro et al. (2017) had a majority of their patients

under the Wilkes Stage III-V category. Furthermore, the 2017 study found that similar conclusions

were drawn in a 2004 study by Nyberg et al.14,15

Most post-operative complications were minor, with only one case where major

complications were observed. It is important to note that these major complications were not the

result of arthroplasty, but due to a previously completed arthroscopy. Common complications

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included minor scarring and temporary muscle weakness due to impingement or stretching of the

facial nerve. Most patients experienced weakness due to the frontal branch of the facial nerve with

fewer experiencing weakness due to both the frontal and zygomatic branch. There were no reported

cases of weakening due to only the zygomatic branch.

Limitations arose as ranges of motion within charts were often drawn out with missing

values or simply stated that there was an improvement in the range of motion. Other times the

information was given with only one of the IID measurements. The Wilkes classification was not

always stated directly, and it is recommended to be filled in for all future follow up appointments.

It would be beneficial to have set guidelines for the information that is to be gathered at each

appointment, similar to the data capture sheet formed for this study.

The number of cases making up the patient pool further presented a limitation. Although

the number of cases was similar to those in previous studies, only 36 cases were found within the

years of 2011-2017. Due to arthroplasty being a last resort surgery in an attempt to save the TMJ,

the frequency of the surgery is restricted. When the TMJ has reached an irreparable stage, total

joint replacement (TJR) is indicated.

Diagnosis and experience are integral in deciding the surgical procedure performed by the

attending physician. Ideally, equal exposure in the number of eminectomy and discectomy cases

would have been desired in yielding more accurate results. Retrospective studies have the inability

to randomly assign patients to discectomy, eminectomy or both, leading to further limitations. A

larger sample size would be needed to tabulate more data in order to compensate for the lack of

diversity in surgical procedures.

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Conclusion

Although pain and/or dysfunction due to abnormalities in the temporomandibular joint,

masticatory muscles and all supporting structures can be treated in a variety of effective ways,

arthroplasty shows promising results for some TMD patients. While arthroscopy and

arthrocentesis are found to be considerably successful in alleviating pain and symptoms in most

TMD patients, few patients are occasionally left with pain or limited ranges of motion. Not only

does arthroplasty show minimal post-operative complications, a significant reduction in pain and

increase in range of motion is observed. From the data analyzed in this study, we conclude that

TMJ arthroplasty with eminectomy and discectomy is an effective and definitive surgery for the

treatment of refractory TMD.

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