Joint and Muscle Dysfunction of the Temporomandibular Joint (Cells Tissues Organs ( Formerly ACTA Anatomica )) (v. 174, No. 1-2)

100 Pages·2003·2.77 MB·English

by  Arthur W. English

Joint and Muscle Dysfunction
of the Temporomandibular Joint
Guest Editor
Arthur W. English,Atlanta, Ga.
42 figures, 4 in color, 2 tables, 2003
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Vol. 174, No. 1–2, 2003
Contents
5 Preface
English, A.W. (Atlanta, Ga.)
6 ‘Friction and Adhesive Forces’ – Possible Underlying Causes for
Temporomandibular Joint Internal Derangement
Nitzan, D.W. (Jerusalem)
17 Subchondral Bone Resorption in Temporomandibular Joint Disorders
Gruber, H.E. (Charlotte, N.C.); Gregg, J. (Blacksburg,Va.)
26 Nitric Oxide in Experimental Joint Inflammation. Benefit or Detriment?
Wahl, S.M.; McCartney-Francis, N.; Chan, J.; Dionne, R.; Ta, L. (Bethesda, Md.);
Orenstein, J.M. (Washington, D.C.)
34 Pathophysiological Mechanisms in Osteoarthritis Lead to Novel
Therapeutic Strategies
Malemud, C.J.; Islam, N.; Haqqi, T.M. (Cleveland, Ohio)
49 Analgesic Effect of Elastoviscous Hyaluronan Solutions and the
Treatment of Arthritic Pain
Balazs, E.A. (Ridgefield, N.J.)
63 Induction of Early Growth Response Gene Egr2 by Basic Calcium
Phosphate Crystals through a Calcium-Dependent Protein Kinase C-
Independent p44/42 Mitogen-Activated Protein Kinase Pathway
Zeng, X.R.; Sun, Y.; Wenger, L. (Miami, Fla.); Cheung, H.S. (Miami, Fla./
Coral Gables, Fla.)
73 Specialized Cranial Muscles: How Different Are They from Limb and
Abdominal Muscles?
Sciote, J.J.; Horton, M.J. (Pittsburgh, Pa.); Rowlerson, A.M. (London); Link, J.
(Pittsburgh, Pa.)
87 Sex Differences in Rabbit Masseter Muscle Function
English, A.W. (Atlanta, Ga.); Widmer, C.G. (Gainesville, Fla.)
97 Author Index Vol. 174, No. 1–2, 2003
98 Subject Index Vol. 174, No. 1–2, 2003
99 Conference Calendar
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Cells Tissues Organs 2003;174:5
DOI: 10.1159/000070569
Preface
Temporomandibular (jaw) joint diseases and disorders of investigators studying TMJ problems. One result of the
are estimated to affect 10 million Americans every year first meeting in May 2000 was the publication of a series
with the majority of those seeking treatment being women of papers in Cells Tissues Organs (Vol. 169, No. 3, ISBN
in their childbearing years. These conditions commonly 3–8055–7229–8). That first meeting, called Moving TMJ
referred to as ‘TMJ’ represent a family of complex and Research into the 21st Century, provided a broad over-
poorly understood health problems manifested by pain in view of TMJ disorders and elicited a number of fresh
and around the jaw and associated muscles and limita- ideas and new perspectives. It was clear, however, that no
tions in the ability to make to normal movements of single scientific meeting on TMJ disorders could encom-
speech, facial expression, eating, chewing, and swallow- pass the many basic and clinical disciplines needed to
ing. Conditions that routinely affect other joints in the advance the field. The organizers agreed that future meet-
body, such as arthritis and trauma, also affect the TMJ. ings should focus on selected aspects of TMJ disorders,
Researchers generally agree that the most common tem- while retaining a commitment to an integrated, broad-
poromandibular diseases and disorders fall into three based, interdisciplinary approach. Accordingly, the sec-
main categories: arthritis, internal derangement of the ond meeting of the association, held in May 2002, was
joint, and/or myofascial pain. Currently there are no focused on the role that osteoarthritis and muscle me-
established treatments for TMJ conditions, so that the chanics play in TMJ diseases and disorders. This special
therapies patients receive generally reflect the personal topics issue of Cells Tissues Organs is a selection of papers
views and practices of the provider, which, all too often, presented at the second meeting. It is titled: Joint and
can lead to a worsening of their condition. Muscle Dysfunction of the Temporomandibular Joint.
The TMJ Association (TMJA) is a national nonprofit We are delighted to be able to publish these fine papers
organization dedicated to advancing understanding and and hope that their circulation will continue to stimulate
treatment of temporomandibular diseases and disorders. TMJ clinical and basic research as was the case with the
In its work to promote research and improve diagnosis, publication of the earlier set of papers.
treatment, and prevention, the association has held two Arthur W. English, Atlanta, Ga.
scientific meetings, aimed in part at broadening the base
ABC © 2003 S. Karger AG, Basel
1422–6405/03/1742–0005$19.50/0
Fax [phone]
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Cells Tissues Organs 2003;174:6–16
DOI: 10.1159/000070570
‘Friction and Adhesive Forces’ – Possible
Underlying Causes for Temporomandibular
Joint Internal Derangement
D.W.Nitzan
Department of Oral and Maxillofacial Surgery, The Hebrew University Hadassah School of Dental Medicine,
Jerusalem, Israel
Key Words Introduction
FrictionW Adhesive forcesW Temporomandibular jointW
Internal derangementW Open lockW Anchored disc Temporomandibular disorder refers to various dental
phenomenonW Osteoarthritis and medical conditions affecting the temporomandibular
joint (TMJ), masticatory muscles and contiguous tissue
components. The wide use of temporomandibular disor-
Abstract der by clinicians and researchers avoiding a precise diag-
Since normal temporomandibular joint (TMJ) move- nosis has led to a great deal of meaningless research and
ments depend primarily on the disc freely sliding down indiscriminate treatment.
the slope of the eminence, understanding how aberra- The common phenomenon of multiple TMJ surgery
tions in the lubrication system contribute to TMJ dys- clearly suggests a lack of basic understanding of TMJ
function is clearly critically important. It provides a possi- internal derangement. With the aim of reducing iatrogen-
ble explanation for the genesis of disc displacement and ic TMJ insults, an increasing number of studies are
helps make us familiar with the clinical appearance and directed toward the intra-articular, biomechanical and
ways of treating limited mouth opening caused by the biochemical events underlying TMJ internal derange-
anchored disc phenomenon (ADP) versus disc displace- ment.
ment without reduction, TMJ open lock versus disloca-
tion and osteoarthritis. This understanding clarifies the
efficiency of procedures such as joint hydraulic pump,
Abbreviations used in this paper
arthrocentesis and arthroscopic lavage and lysis particu-
larly in ADP, open lock and osteoarthritis.
ADP anchored disc phenomenon
Copyright © 2003 S. Karger AG, Basel HA hyaluronic acid
PL phospholipid
PLA phospholipase A
2 2
SAPLs surface-active phospholipids
SF synovial fluid
TMJ temporomandibular joint
ABC © 2003 S. Karger AG, Basel D.W. Nitzan
1422–6405/03/1742–0006$19.50/0 Department of Oral and Maxillofacial Surgery
Fax [phone] Faculty of Dental Medicine, PO 12272
E-Mail [email protected] Accessible online at: Jerusalem 91120 (Israel)
www.karger.com www.karger.com/cto Tel. [phone], Fax [phone], E-Mail [email protected]
Displacement of the articular disc in the TMJ from its surface energy, which is much less conducive to friction
normal position was described and identified as a poten- than exposed articular surfaces (without SAPL) [25].
tial clinical problem over 100 years ago [1]. In the 1950s, Good cohesion, an essential factor in load bearing, is pro-
Ireland [1] pointed to this as the first stage in the sequence vided by hydrogen bonding among phospholipid (PL)
of events leading to osteoarthritis. Disc displacement is molecules [25–27]. Under high load, SAPL may attain
the postulated cause of joint pain, limited mandibular very low friction coefficients.
movement, joint sounds and osteoarthrotic changes in the Electron microscopy of sheep knee joint articular sur-
TMJ [3–13]. Although the damage caused by disc dis- faces, using a special fixation technique (essentially sub-
placement has been given much attention, very little stituting tannic acid for glutaraldehyde), revealed multila-
effort has been made to explain the factor(s) behind this mellar structures, 200–300nm in diameter, typical of
phenomenon [3–7]. While surgical procedures to restore SAPL [25, 27].
normal TMJ anatomy and function [14, 15] which ignore Schwarz and Hills [27] showed that lamellar bodies,
the causes of disc displacement have led to ostensibly suc- which are present in type B synoviocytes, are the probable
cessful outcomes, there have been many cases of multiple source of surfactant. Lubricin and proteolipid, which
surgical interventions, sometimes involving severe com- have been isolated from the synovial fluid (SF), seem to
plications [16]. facilitate SAPL deposition, providing efficient boundary
Such iatrogenic insults have stimulated rethinking of lubrication at articular surfaces [28]. Various biomechan-
the role played by disc displacement in TMJ complaints ical studies suggest that PLs play a role in joint lubrication
[17, 18]. Disc displacement was diagnosed in normal indi- [29–32]. Biochemical analysis of articular surfaces and
viduals. It is often not associated with joint pain, and SF, revealing the presence of PLs, primarily phosphatidyl-
diagnosing the origin of pain is important for developing a choline, support the EM findings. Traces of phosphatidyl-
proper treatment plan [19, 20]. In addition, lavage of the ethanolamine and sphingomyelin have also been found
upper joint compartment using arthroscopy [21] or ar- [25, 33–36]. To further confirm their proposed lubrica-
throcentesis [22], neither of which change the disc posi- tion role, the friction in the joint was determined follow-
tion [23, 24], were found to markedly improve function ing SAPL removal from the SF. Thus, lipid solvent
and alleviate pain in disorders such as severe closed lock. applied to the joint articular surface increased the friction
As a result, the focus has shifted from studies on the ‘posi- by 150% [25]. Potent lipid solvents were shown to adsorb
tion of the disc’ to the search for the intra-articular biome- SAPL, thereby reducing hydrophobicity [26]. Addition to
chanical and biochemical events underlying pain and disc SF of phospholipase A (PLA , an enzyme secreted into
2 2
displacement. the SF by the synoviocytes, chondrocytes and osteo-
This review considers the TMJ from a different angle. blasts), which acts specifically on PLs, significantly in-
Since normal TMJ movements depend primarily on free creased friction [37]. As opposed to neutral lipids, Rabi-
sliding of the disc down the slope of the eminence, under- nowits et al. [35] and Punzi et al. [36] reported a dramatic
standing how aberrations in the lubrication system con- decrease in PL levels, concomitant with increased PLA
2
tribute to TMJ internal derangement is clearly critically activity, in the traumatized joint. These findings provide
important. further strong support for SAPLs as active elements in the
joint lubrication system, contributing to protection of
articular surfaces.
Synovial Joint Lubrication Of special interest is the role assigned to HA in the cur-
rent view of the joint lubrication system. A high-molecu-
There is abundant literature on lubrication of large lar-weight mucopolysaccharide, HA, forms a ‘full fluid
synovial joints. Various biomechanical, biochemical and film’, which keeps the articular surfaces apart and pre-
animal studies suggest that two major constituents are vents generation of friction. An in vitro study revealed
responsible for free joint movement: surface-active phos- adherence of HA to PL membranes (liposomes), thereby
pholipids (SAPLs) and hyaluronic acid (HA). protecting it from lysis by PLA [38]. Thus, HA might
2
SAPLs, the major boundary lubricants protecting ar- play an important indirect role in joint lubrication by
ticular surfaces, are highly effective [25–27]. They consist adhering to SAPLs, which are thereby protected against
of a polar component bound to the articular surface, uncontrolled lysis by PLA in the SF [38]. A similar
2
thereby orienting their nonpolar moieties outward. The defense mechanism has been described at the cellular lev-
latter form a hydrophobic surface with a relatively low el [39].
‘Friction and Adhesive Forces’ Cells Tissues Organs 2003;174:6–16 7
TMJ Lubrication or destroy important molecules. Among other effects of
ROS on the joints are the inhibition of HA biosynthesis
An efficient lubrication system in the TMJ is mandato- and degradation, giving rise to a marked decrease in SF
ry for the disc to slide down the slope of the eminence. viscosity [63]. As previously mentioned, reduced viscosity
Lipids, in general, and PLs, in particular, have not does not affect the SF lubrication efficiency [64, 65].
been considered in most studies dealing with TMJ articu- However, as demonstrated in an in vitro study, the
lar surface and SF composition [40–43]. Marchetti et al. degraded form of HA has an indirect effect on joint lubri-
[44] identified an electron-dense layer which was not dis- cation: by not inhibiting PLA activity, it fails to protect
2
cernible in disordered joints. They postulated that this continuity of the SAPL layer [38]. Thus, PLA secreted
2
covering layer maintains proper joint function and pre- into the SF is free to lyse SAPL [38, 39], disrupting the
vents conditions conducive to adherence [44]. Osmio- continuity of the boundary surfactant layer on the articu-
philic layers with embedded vesicular structures have lar surfaces.
been demonstrated in the TMJ, which are similar to the Notwithstanding the accumulating body of knowledge
‘surface coat’ described by others [45–47]. The conven- on the mechanism of joint lubrication and its reciprocal
tional fixation technique for TEM showed the presence of relation to joint loading, whether and how the absence of
PL multilamellar structures with diameters of up to SAPL affects the sliding ability of articular surfaces de-
290nm, similar to those reported by Hills et al. [25]. The serves further discussion.
osmiophilic droplet cluster in centrifuged SF, as described
previously, is degraded following exposure to PLA ,
2
which specifically acts on PL. Joint Performance in the Absence of
Biochemical studies on the SF of normally functioning Lubrication
TMJs revealed the presence of neutral lipids, such as tri-
glycerides, cholesterol and cholesterol esters. Among the The main factors determining the friction between
polar lipids, phosphatidylcholine was dominant with uncovered articular surfaces are relative contact area, sur-
much lower levels of phosphatidylethanolamine and face energy, shear and surface rupture potential, surface
sphingomyelin [48, 49]. Further in-depth studies on the elasticity and applied load [57, 58, 66–70]. The articular
lubrication system might eventually lead to the develop- surfaces are smooth planes [71], implying large contact
ment of appropriate tools for the prevention and treat- areas which, together with the surface elasticity (such as at
ment of TMJ disorders as well as improved intra-articular the disc) and the high surface energy [57, 58, 66–68], lead
injection materials. to increased friction in the absence of lubrication. It
seems reasonable to assume that increased friction even-
tually leads to shear and rupture of articular surfaces,
Joint Overloading and Impaired Lubrication especially the softer planes [48, 49, 57, 72, 73]. There may
also be ‘adhesion forces’ between the flexible disc and the
Joint function remains normal as long as its adaptive fossa. If the fluid film is extremely thin (subboundary lu-
capacity is not compromised [11, 49–56]. Parafunction brication) between the naked surfaces, the resulting high
such as clenching is a good example of repetitive jaw adhesion forces may cause anchoring of the disc to the
motion associated with possible high TMJ impact loading fossa. Such anchorage can be promptly released by lavage
that leads to the conversion of shearing stresses into com- of the adhered surfaces.
pressive stresses [52, 54]. Overloading is the major cause
of collapse of the lubrication system, which has various
effects on synovial joints [51, 57–59], e.g. blood supply Control of TMJ Overloading
interruption [60–63]. When overloaded, the joint intra-
articular pressure increases and, if it exceeds the capillary Very little is known about the actual forces involved in
perfusion pressure, causes temporary hypoxia, which is TMJ function in situ, but weights of up to 17.7kg have
compensated for by reoxygenation on cessation of over- been recorded in Macaca monkeys [55, 56]. Chen and Xu
loading. This hypoxic-reperfusion cycle has been reported [56] found contact stress in human TMJ reached a maxi-
to evoke nonenzymatic release of ROS (i.e., superoxide mum of 1,650 lb/inch2, which is similar to that in the hip
and hydroxyl anions) [60–63]. The highly reactive ROS and knee joints. In weanling pigs, intra-articular pressure
may enter into rapid chemical reactions in various tissues in the superior TMJ compartment was as high as 20mm
8 Cells Tissues Organs 2003;174:6–16 Nitzan
Hg during masticatory movement [74]. In awake humans, joint disease, masticatory muscle spasm and increased
intra-articular pressure ranging from 8 to 200mm Hg friction between moving parts. To the current general
(mean 63.9 B 52.25mm Hg) has been documented dur- consensus, TMJ disc displacement results from its inabili-
ing clenching [52]. Pressure of over 40mm Hg, which ty to slide smoothly due to increased friction or degenera-
may occur in clenching, exceeds the capillary perfusion tive changes in the joint surfaces [50, 51, 80–92]. The
pressure. This may elicit temporary hypoxia, followed by sequence of events, starting with increased friction in the
reoxygenation on cessation of the activity [60–63]. Rest, upper joint compartment and culminating in disc dis-
which is beneficial for other symptomatic synovial joints, placement, has been described [93] and is best visualized
is not indicated for the TMJ, since parafunction is essen- schematically (fig.1a–e). Activation of various parafunc-
tially an uncontrollable behavior occurring during the tions, such as clenching (fig.1a), compromises the lubri-
night. For example, an interocclusal appliance along the cation system in the upper TMJ compartment. The result-
lines of a lever III system, which reduces the force on the ing increased friction prevents the disc from sliding
TMJ, is a most efficient and immediate way to control the together with the condyle. On jaw opening, the condyle is
forces generated in the TMJ [52]. Indeed, such appliances pulled away from the disc by the inferior head of the later-
can reduce the pressure generated in the joint during al pterygoid muscle (fig.1b). As a result, the ligaments
clenching by 81.2% [52]. This is not unlike the effect of joining the disc to the condyle are gradually stretched
different bandaging techniques as an adjunct to orthope- (fig.1c), and the ‘mobilized’ disc gravitates slightly down-
dic management. ward and forward. Subsequently, on clenching, the unsta-
ble disc is propelled forward by pressure from the con-
dyle. At this point, the force on the slightly displaced disc
TMJ Arthrocentesis is shared between two vectors, one of which is directed
forward [Mow, pers. commun.]. Apparently, on mouth
Arthrocentesis, a treatment modality for various TMJ closure, the superior belly of the lateral pterygoid muscle
disorders [75–77], consisting of saline injection and la- pulls the disc anteriorly (fig.1d). Subsequently, during
vage of the upper compartment in arthrocentesis, forces mouth opening, the condyle, which is now posterior to the
apart the disc from the fossa and then washes away loose disc, gradually pushes it down the slope of the emi-
degraded particles and inflammatory components, in- nence, displacing it further forward (fig.1e). Since the lat-
cluding ROS and PLA . An arthrocentesis outflow of eral articular disc bears the bulk of the shearing and com-
2
100 ml is recommended, since with smaller volumes, pressive loads, persistent loading tends to drive it in a
denatured hemoglobin and various proteinases have been medial direction, which is the ‘path of least resistance’
recovered in various fractions [78, 79]. TMJ unloading [Mohl, pers. commun.].
combined with residual adhered PL and HA may become The arthrographic visualization of TMJs with disc dis-
a milestone in rehabilitating the joint lubrication system. placement exhibits an intriguing feature. The anterior
Further studies along these lines may lead to more effec- wall of the inferior compartment, which should be
tive intra-articular medication and improve outcomes. stretched by the displacement of the disc, is markedly dis-
tended and situated in front of the condyle under the disc
(fig.2). This can be explained in terms of the proposed
Clinical Applications underlying pathogenesis of disc displacement. Thus, the
increased friction between the disc and the fossa leads to
Better understanding of the TMJ lubrication system malformation of the lower compartment (see above).
and its possible collapse provides new insights into joint Namely, on mouth opening, the condyle is pulled for-
disorders, such as disc displacement, severe closed lock, ward, away from the disc, which moves more slowly,
open lock and degenerative joint disease. while stretching the anterior ‘wall’ of the inferior compart-
ment (fig.1b). In the course of time, the anterior wall of
TMJ Disc Displacement the inferior compartment gradually becomes distended,
The most common TMJ signs and symptoms, such as as seen in the arthrographic image in figure2. This typical
joint clicking, closed lock and crepitation, are associated feature of disc displacement with and without reduction
with disc displacement. The etiologies for this condition indirectly illustrates the role of friction in loosening and
as mentioned in the literature are various types of acute displacing the link between the disc and condyle [91].
trauma, functional overloading, joint laxity, degenerative
‘Friction and Adhesive Forces’ Cells Tissues Organs 2003;174:6–16 9
Fig. 1. The process of disc displacement in the TMJ. a During joint inclining forward and downward along the slope of the eminence.
overloading (e.g., clenching; arrowhead), the disc is pressed against d On clenching, the loosened disc is propelled forward by the press-
the fossa. The intermittently increasing intra-articular pressure may ing condyle (arrowhead). At the same time, the disc is pulled forward
generate reactive oxidative species. b Collapse of the lubrication sys- by the superior belly of the lateral pterygoid muscle. e On mouth
tem in the presence of ROS produces friction between the disc and opening, the condyle, which at this time is located posterior to the
the fossa (arrowhead). On mouth opening the condyle is pulled away disc, is pulled by the inferior head of the lateral pterygoid muscle
from the slow-moving disc (arrow), and the condyle-disc connection (arrow), pushing the disc into an anterior-medial-inferior direction
slackens gradually. c The disc is loosely connected to the condyle, (white arrow).
10 Cells Tissues Organs 2003;174:6–16 Nitzan