Evaluation of Pain Regression in Patients with Temporomandibular Disc Displacement with Reduction Treated by Intra-Articular Platelet-Rich Plasma Injections versus Arthrocentesis

Introduction

Patients with anterior disc displacement with reduction (DDWR) most frequently suffer from pain which is one of the most common orofacial pains with a prevalence of about 6 % worldwide [1]. The continuum of symptoms also includes limited, asymmetric mandibular motion and TMJ sounds.

Current treatments of the DDWR are largely targeted at symptomatic relief of joint pain and improvement of mandibular range of motion. Treatment approaches vary depending on the symptoms and degree of dysfunction[2] . Treatment regimens can include medication, occlusal appliances, physical therapy modalities, mobilization, exercises, minimally invasive procedures (arthrocentesis and arthroscopic procedures) and open surgical interventions that are only used when all other possible therapeutic options have been exhausted[3,4] .

Opinions about the treatment of DDWR are as controversial as beliefs about its etiology and therefore, the management of this disorder should begin with conservative, reversible measures and escalate slowly to irreversible procedures if necessary. Minimally invasive procedures are recognized increasingly as first line intervention in patients who do not respond to conservative management [5, 6]. Of these procedures, arthrocentesis and intra-articular injectionof platelet rich plasma (PRP) have been applied with varying degrees of success.

Preliminary findings gave encouraging results for the use of PRP in temporomandibular joints (TMJ) with inflammatory/degenerative processes[7]. PRP is a natural concentrate of blood growth factors and is thought to deliver activated platelets which play an important role in coagulation, haemostasis, have analgesic properties by releasing protease activated receptor 4 peptides. When injected, the activated platelets secrete numerous proteins including growth factors, such as (platelet derived growth factor, transforming growth factor ß, vascular endothelial growth factor), endostatins, platelet factor 4 and angiopoietins; all of which are involved in the healing process[8]. Thus PRP may reduce inflammation, provide pain relief, improve function and stimulate possible cartilage regeneration at the site of injury [9, 10].

Subjects and Methods

Patients with clinical findings of pain in the involved joint, difficulty in mouth opening, restriction in movement, and clicking sound were evaluated clinically and with magnetic resonance images (MRI).

Clinical examination

Each patient was asked to point to the site of pain using one finger. Pointing to TMJ denotes articular disorder. The right and left TMJs were palpated bilaterally via preauricular approach during opening and closing of the mouth to determine the presence of joint sound and tenderness. The maximal mouth opening (MMO) was measured by the distance in mm between the incisal edges of the upper and lower incisors using a ruler.

MRI examination

Preoperative T1-weighted and T2-weighted MRIs for right and left joints in closed and maximum mouth opening positions were requested for each patient

PRP Injection Technique

          PRP preparation

An even number of the tubes were placed in the rotor of the Hettich Universal 32R Refrigeration Centrifuge and spun at 3200 rpm for15 minutes. This separates the blood into 3 distinct layers: with platelet-poor plasma (PPP) as the top yellow layer; a middle buffy coat layer containing platelets and leukocytes; and a red bottom layer containing red blood cells. Inside a biosafety cabinet, the buffy coat layer and the lower one third of PPP were aspirated from the test tubes using a micropipette and transferred into sterile microcentrifuge tube. Hereafter, the procedure was completely performed inside the biosafety cabinet. The microcentrifuge tube was shaken for 10 seconds to resuspend the platelets. 1 mL of PRP for each TMJ was supplied for intra articular injection.(fig1)

Figure (1): Steps A through E demonstrate the steps required for PRP preparation.

Technique

A line was drawn from middle of the tragus to the outer canthus of the eye. The entrance point is located along the canthotragal  line,10 mm from the middle of the tragus and 2mm below the line. Auriculotemporal nerve block anesthesia wa performed using one carpule of Mepicaine L[1]. An 18 gauge needle of 10 ml plastic syringe loaded with normal saline solution was inserted into the superior joint compartment (SJC). The saline solution was then injected. The joint entry was confirmed by the presence of rebound pressure on the piston of the syringe and the flow back of some drops of the solution on removal of the syringe’s barrel from the needle after injection.  The saline solution was injected in the SJC under manual pressure with the patient in a mouth-open position, in order to expand the joint cavity and then it was withdrawn. The injection-ejection process was repeated 10 times. Then 1ml of PRP is injected into the SJC and the needle was withdrawn. At the end of the procedure, the patient was asked to open and close the mouth several times for a minute to ensure equal distribution of PRP.(fig 2)

Figure (2): Steps A through F demonstrate the steps for the PRP injection Technique

Arthrocentesis Technique

Two points were marked on the skin over the articular fossa and eminence along a line drawn from the middle of the tragus to the outer canthus of the eye. The posterior inlet point was located along the canthotragal line 10 mm from the middle of the tragus and 2 mm below that line. The anterior outlet point was located 20 mm from the middle of the tragus and 8 mm below the canthotragal line.  Auriculotemporal nerve block anesthesia was performed using one carpule of Mepicaine L. Subcutaneous injection of Mepicaine L at the inlet and outlet points was performed to augment the auriculotemporal nerve block anesthesia.

About 1cm spacer was placed between teeth to increase the intra-articular space and to stabilize and fix the condylar position at the operated side during injection. A 18 gauge needle was inserted into the SJC through the posterior inlet point and 2ml of saline solution was injected to distend the joint space. The joint entry was confirmed by the presence of rebound pressure on the piston of the syringe.  At the outlet anterior point another 18 gauge needle was inserted into the distended compartment.Lavage of the SJC with 100 ml of normal saline solution was performed manually to establish free flow of the washing solution. The needles were then removed and the patient was asked to gently manipulate his or her jaw in vertical, protrusive and lateral excursion to remove any excess of intra-articular fluid.(fig 3)

Figure (3): Steps A through F demonstrate the steps for the Arthrocentesis technique

Results

Tables 1, 2 and 3 summarize demographic characteristics of both groups.  There is no significant difference in either age or duration of symptoms between both groups.

Table 1: Descriptive statistics and independent student “t” test comparing age (years) in both groups.

Table 2: Frequency distribution of sex in both groups

Table 3: Frequency distribution of affected side in both groups

Clinical results

   I.    TMJ pain

The assessment of the TMJ pain throughout the study intervals is shown in table 4. There is statistically significant reduction in pain intensity in both groups after 2 and 4 weeks. After 8 weeks pain score is “zero” in both groups.There is no statistically significant difference between both groups preoperatively and after 2 and 4 weeks.