Background
The
temporomandibular joint (TMJ) is a bilateral synovial articulation between the
mandible and temporal bone. The name of the joint is derived from the two bones
which form the joint: the upper temporal bone which is part of the cranium
(skull), and the lower jaw bone or mandible [1]. The common features of the synovial joints
exhibited by this joint include a disk, bone, ?brous capsule, ?uid, synovial
membrane and ligaments. However, the feature that differentiate and make this
joint unique is its articular surface covered by ?brocartilage instead of
hyaline cartilage. Movement is not only guided by the shape of the bones,
muscles, and ligaments but also by the occlusion of the teeth, since both
joints are joined by a single mandible bone and cannot move independently of
each other [2]. Temporomandibular joint
disorders (TMD) are among the most misdiagnosed and mistreated maladies in
medical practice. TMDs is a collective term for conditions including pain
and/or dysfunction of the temporomandibular joint involving either muscular or
skeletal structures or both. The condition
characterized by clinical signs of pain or malfunction occurring in the
temporomandibular joint or muscles of mastication, articular sounds (clicking)
and abnormities in mandibular movements [3]. Temporomandibular joint disorders (TMDs) affect
the jaw joints and related structures and includes painful myofascial problems,
internal derangement of joint space, degenerative and rheumatologic problems.
TMD is characterized by pain, joint noise, a limited range of motion, impaired
jaw function, deviation or de?ection upon mouth opening, malocclusion, and
closed or open locking [4]. Internal derangements
that result in progressive displacement of the articular disc are present in a
proportion of TMD cases. Anterior disc displacement with reduction refers to an
unnatural forward movement of the disc during opening, which reduces on
closing. When there is a tear in the back part of the joint capsule, called a
retrodiscal ligament, the articular disc may be displaced forwards (anterior
disc displacement). The upper head of the lateral pterygoid muscle normally
acts to stabilize the disc; however, the disc displacement makes it ineffective
and the lower head tries to compensate, thus producing abnormal muscle activity
during mouth closure [4,5].Anterior disc displacement without reduction refers
to an unnatural forward positioning of the articular disc, which does not
reduce when the mouth is closed. The articular surfaces of the bones are
exposed to a greater degree of wear, which may progress to (OA) in later life
[6]. There are essentially
two types of therapy for temporomandibular joint (TMJ) disorders – conservative
(non-invasive) and surgical (invasive), during which the joint structures
themselves are entered. A number of conservative methods are used in the
treatment of temporomandibular joint internal derangement, including occlusal
splints of various designs, supportive physical therapy procedures,
rehabilitation involving muscular training, and specialist psychological
support. Surgical treatment can be divided into invasive (open) and minimally
invasive (which includes arthrocentesis and arthroscopy) [7]. In internal derangement
the protocols for initial treatment consists of choosing reversible and little
invasive therapies, such as occlusal splints, non-steroidal anti-inflammatory
drugs (NSAID), analgesics, physiotherapy and patient advice. However, in some
cases, conservative treatment becomes little responsive due to current
structural changes. Thus, more complex procedures such as intra-articular
injections with corticosteroids or hyaluronic acid, arthrocentesis appear as
therapeutic options to control and treat TMJ internal derangements [6].
Intra-articular administration of medications is an established method of
treatment, particularly in orthopedic and rheumatic disorders associated with
pain, effusion, inflammation of cartilage, and bone and joint capsules as well
as fibrous adhesions. Currently, agents used for intra-articular injection
within the temporomandibular joint regions include hyaluronic acid and steroids
[8]. Current research is investigating new methods of stimulating repair or
replacing damaged cartilage, such as matrix metalloproteinase inhibitors, gene
therapy, cytokine inhibitors, arti?cial cartilage substitutes, and growth
factors. The in?uence of the growth factors in cartilage repair is now being widely
investigated in vitro and in vivo. Platelet-rich plasma (PRP) is a natural
concentrate of autologous growth factors from the blood. The method is simple,
low cost, and minimally invasive. Currently, a wide range of experiments is
taking place in different ?elds of medicine in order to test the potential of
enhancing tissue regeneration [9]. PRP has been used clinically in humans for
its healing properties attributed to the increased concentrations of autologous
growth factors and secretory proteins that may enhance the healing process on a
cellular level. The hope is that PRP enhances the recruitment, proliferation,
and differentiation of cells involved in tissue regeneration. The rationale for
the use of PRP is that the supraphysiological release of platelet-derived
factors at the direct site of cartilage injury or disease can stimulate the
natural healing cascade and tissue regeneration. Platelet activation leads to a
release of a hundred of growth factors from its ?-granules to promote cartilage
matrix synthesis, increase cell growth, migration, and phenotype changes, and
facilitate protein transcription within chondrocytes [10]. Hyaluronic acid (HA)
is naturally found in body and joints. It enhances lubrication and facilitates
joint movement. TMJ patients were diagnosed with ID, suffer considerable
diminish of HA levels at their joints [8]. Although,
hyaluronic acid safety and efficacy compared to corticosteroids but it is also
costly effective and its half-life
within the joint is very short.
Studies
of the efficacy of intra-articular TMJ injections have shown mixed results,
with improvement in some patients and disease progression in others. Reports of
intra-articular corticosteroid injections to the TMJ showing that high doses of
corticosteroids were increasing the risk of aseptic bone necrosis. Also,
patients with severe damage may be less responsive to intra-articular
corticosteroids, and require multiple injections to treat persistent, severe
TMJ symptoms [8]. Current methods of intra-articular drug injection often
require frequent injections that have a high financial burden, impact patient
quality of life, and also increase the risk of complications. Immediately
following each intra-articular injection, patient joint activity (e.g.,
chewing, talking, etc.) is restricted so as to minimize the risk of either
joint overload or tissue reaction resulting in increased drug clearance, so,
the need for a material to be safe, low cost, effective in reliving symptoms
and able to induce tissue regeneration is evoked [5]. Visco-PRP is a mixture of
PRP and HA. Visco-PRP injection showed good chance for combing two different
materials with different moods of action as a treatment of ID [11].