CRANIO® The Journal of Craniomandibular & Sleep Practice ISSN: 0886-9634 (Print) 2151-0903 (Online) Journal homepage: http://www.tandfonline.com/loi/ycra20 Liquid platelet-rich fibrin injections as a treatment adjunct for painful temporomandibular joints: preliminary results Jonathan B. Albilia DMD, MSc, Carlos Herrera- Vizcaíno DDS, Hillary Weisleder BSc, Joseph Choukroun MD & Shahram Ghanaati MD, DMD, PhD To cite this article: Jonathan B. Albilia DMD, MSc, Carlos Herrera- Vizcaíno DDS, Hillary Weisleder BSc, Joseph Choukroun MD & Shahram Ghanaati MD, DMD, PhD (2018): Liquid platelet-rich fibrin injections as a treatment adjunct for painful temporomandibular joints: preliminary results, CRANIO®, DOI: 10.1080/08869634.2018.1516183 To link to this article: https://doi.org/10.1080/08869634.2018.1516183 Published online: 20 Sep 2018. Submit your article to this journal View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ycra20 ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE https://doi.org/10.1080/08869634.2018.1516183 TMJ Liquid platelet-rich fibrin injections as a treatment adjunct for painful temporomandibular joints: preliminary results Jonathan B. Albilia DMD, MSca, Carlos Herrera- Vizcaíno DDSb, Hillary Weisleder BScc, Joseph Choukroun MDd and Shahram Ghanaati MD, DMD, PhDe a Private Practitioner and Attending, Division of Oral and Maxillofacial Surgery, Department of Dentistry, Jewish General Hospital, Montreal, Canada; bDepartment for Oral, Cranio-Maxillofacial and Facial Plastic Surgery. FORM (Frankfurt Orofacial Regenerative Medicine) Lab, University Hospital Frankfurt Goethe University, Frankfurt am Main, Germany; cFormerly Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada; Currently, MD Candidate, New York Medical College, New York, NY, USA; dPrivate Practitioner, Pain Therapy Center, Nice, France; eDepartment for Oral, Cranio-Maxillofacial and Facial Plastic Surgery, FORM (Frankfurt Orofacial Regenerative Medicine) Lab, University Hospital Frankfurt Goethe University, Frankfurt am Main, Germany ABSTRACT KEYWORDS Objective: To evaluate the clinical benefits of liquid platelet-rich fibrin (PRF) in patients with temporomandibular joint (TMJ) pain and dysfunction. Methods: Forty-eight TMJs in 37 patients with painful internal derangement (ID) (Wilkes’ I–V) were included. Patients were injected with 1.5–2cc of PRF within the superior joint space at 2week intervals. Pain and subjective dysfunction were recorded using a visual analog scale. Statistical analyses were done using the ANOVA test. Results: Thirty-three of 48 TMJs (69%) showed significant reduction in pain at 8 weeks, and at 3, 6, and 12 months (Responders). Fifteen of 48 TMJs (31%) did not improve (Non-responders). The best Responders to liquid PRF injections were ID stages Wilkes’ IV (78.5%) and V (100%), compared to Wilkes’ I (0%), II (47%), and III (33%). A non-significant, but notable decrease in dysfunction was found. Conclusion: Preliminary findings support that liquid PRF exhibits long-term analgesic effects in most patients with painful TMJ ID. Arthritis; TMJ internal derangement; liquid platelet-rich fibrin; tissue engineering; pain; i-PRF; LSCC; low-speed centrifugation concept Introduction The temporomandibular joint (TMJ) is a key component in the functioning of the stomatognathic system, and as a system, derangement of components due to external or internal articular overloading, e.g., parafunctional habits, altered occlusion or degenerative pathologies, can cause a continuous cycle of reactions leading to structural joint deterioration [1]. TMJ internal derangement is one of the most common forms of TMJ disorders, affecting 10% of the population worldwide, with a higher prevalence in young females [2]. The term denotes a disruption in the relation between the articular eminence, the articular disc, and the condyle, which in turn interferes with joint nutrition, waste removal, lubrication and stabilization, blood supply, and local delivery of systemic medications [1,3,4]. Internal derangement of the TMJ includes conditions like anchored disc phenomenon and disc displacement with and without reduction [2]. These variations in the disc-condyle relation can cause an increase in the physiological internal articular pressure (IAP) of the TMJ and collapse of blood perfusion [5], which leads to erosion of the synovial membrane and increases hypoxic-reoxygenation cycles. Such cycles are associated with non-enzymatic release of highly reactive oxidative species (superoxide anions and hydroxyl anions) that trigger a rapid chemical reaction (Fenton’s reaction) [6], causing damage to key biomolecules in the synthesis of hyaluronic acid (HA) and synovial fluid (SF). The reduced viscosity of the SF increases joint friction, adherence, and rupture of articular surfaces, thus initiating a state of chronic inflammation, synovitis, capsulitis, and ultimately, fibrous adhesions [1,3,7,8] (Figure 1). The tendency of non-invasive treatments to painful or degenerative TMJ internal derangements seeks to cut the cycle of deterioration by the intraarticular administration of various drugs, like long-lasting antiinflammatories, such as tenoxicam or etodolac, which CONTACT Dr. Shahram Ghanaati shahram.ghanaati@me.com Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ycra. © 2018 Informa UK Limited, trading as Taylor & Francis Group 2 J. B. ALBILIA ET AL. Figure 1. Pathophysiological cycle of temporomandibular joint (TMJ) deterioration after excessive loading and the establishment of a degenerative pathology. are non-steroidal anti-inflammatory drugs (NSAIDs), or like corticosteroids, that function by means of reducing the biosynthesis of prostaglandins through direct inhibition of cyclo-oxygenase (COX), and consequently, reduce inflammation [9–11]. Although this category of drugs remains effective insofar as immediate analgesia is concerned, their effect on cartilage metabolism and viability raises concerns [12,13]. The term viscosupplementation, introduced in the 1970s, indicates the restoration of the properties of SF (viscosity, shock absorbing, elasticity, and nutrition [14]) by intraarticular injections of a high or low molecular weight elastoviscous solution of hyaluronan, also called HA [15]. Even though numerous studies report many benefits, HA preparations possess short half-lives, and when compared to other drugs, these have not shown significant advantages [10,15,16]. The two previous drugs described do not possess intrinsic reparative biological features; however, biological effects have been described. These effects are likely due to the restoration of the joint environment, but the literature lacks an explanation as to the long-term clinical benefits observed. Biosupplementation is the latest trend in the field; the term indicates a restoration of joint rheology, anti-inflammatory, and anti-nociceptive effects, the normalization of endogenous HA synthesis, and cartilage regeneration [17]. Platelet-rich plasma (PRP) is a first-generation platelet concentrate from centrifuged blood with a weak fibrin network in a liquid or gel form used after activation by thrombin and calcium. PRP has been described as a biosupplement for TMJ derangement with properties including anti-inflammatory, analgesic, and antibacterial. PRP is also thought to restore intraarticular HA properties, glycosaminoglycan synthesis by chondrocytes, balance joint angiogenesis, and it has also been postulated to provide a scaffold for stem cell migration. PRP was introduced in 1998, emphasizing the growth factor content following platelet degranulation [18]. Due to the content of growth factors in PRP, there has been an increase in the use of these concentrates in the last decade in the maxillofacial surgery and orthopedic disciplines. Nevertheless, PRP developers aimed at removing leukocytes from blood concentrates, even though it has been shown that they play an important role in growth factor release and in different phases of wound healing [19]. Furthermore, PRP can carry numerous complications (coagulopathies, antibodies to factors V and XI), and its tedious preparation renders its use impractical in many outpatient clinical settings. In ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE 2001, a second-generation blood concentrate was developed and termed platelet-rich fibrin (PRF), with numerous advantages and without the need for anticoagulants or clotting activators (Figure 2). The developed PRF is characterized by a strong three-dimensional fibrin matrix in a coagulated state, which serves as a medium for the slow and sustained release of growth factors, as well as a scaffold for angiogenesis [22]. In 2017, the low-speed centrifugation concept (LSCC) was introduced as a means of optimizing the content and distribution of cells and growth factors found within PRF matrices [23]. By lowering the relative centrifugation force (RCF) and maintaining a centrifugation time of 8 min, a liquid PRF matrix was generated, with an even higher concentration of immune cells, platelets, and growth factors, e.g., VGEF and TGF-β1, compared to previously described solid PRF matrices [23,24]. Based on these results, the influence of the RCF on the liquid PRF matrices was analyzed using a stepwise decrease of the RCF (966– 60 g-force) with a lower centrifugation time of 3 min. The results highlight a significantly higher number of inflammatory cells, platelets, and significantly higher growth factor/cytokine release in the low-RCF liquid PRF preparation (700 rpm; 60 g for 3 min) [25]. Furthermore, in the clinical setting, the physiologic coagulation of the liquid PRF formulation allows for an easier handling and optimization of bone substitutes, highlighting its biological activity [26–30]. As a 3 result of its biological potential, this study introduces this naturally-derived matrix for the first time as an alternative or adjunct for treating painful internal derangements of the TMJ. The aim of this preliminary study is to evaluate to what extent liquid PRF improves subjective pain and dysfunction in patients with painful TMJ internal derangement. Materials and methods Patients A level II prospective case study with a 12-month follow-up was designed through a multicenter collaboration. This study followed the Declaration of Helsinki on medical protocol and ethics. Patients were informed about the treatment protocol, and a written consent was signed by all participants. All voluntarily-enrolled patients were also offered the more conventional treatment for their disease state, e.g., arthroscopic lysis and lavage, disc plication, discectomy, etc. Some study patients had ongoing splint therapy; however, no patients began splint therapy or other adjunctive therapy during the injection protocol or post-treatment follow-up period. The study took place at the Natix Oral Surgery Clinic in Montreal, Canada between April 2015 and October 2016. Patients were selected according to the following inclusion and exclusion criteria: Figure 2. Characteristics and differences between platelet-rich plasma (PRP) and platelet-rich fibrin (PRF). PRP requires platelet activation by thrombin and calcium chloride during its preparation[20]; on the other hand, PRF is obtained through a one-step centrifugation protocol without the requirement of an additive. The development of PRP is aimed to exclude the presence of white blood cells (WBCs) and increase the content of platelets and fibrin. Conversely, the latest developed “Low-speed centrifugation concept” introduced new PRF matrices with a higher content of white blood cells, platelets, and release of growth factors. A higher content of white blood cells has been shown to play an important role in wound healing[19]. The released measurements of growth factors increased in the liquid PRF when it was centrifuged using a low relative centrifugation force [21]. 4 J. B. ALBILIA ET AL. ● Inclusion criteria: Any degree of TMJ internal derangement and localized TMJ pain. ● Exclusion criteria: Autoimmune diseases, major mechanical obstruction to mouth opening, acute capsulitis, benign or malignant TMJ lesions, neurologic disorders, blood discrasias, and myofascial pain and dysfunction. Thirty-seven patients fulfilled the inclusion criteria, and 48 TMJs in total were classified and treated independently. Clinical evaluation was used for the classification of the TMJ internal derangement according to Wilkes’ classification and confirmed by MRI in the majority of cases [31] (Table 1). Patients’ gender, previous treatments and pain/dysfunction were recorded (unilateral or bilateral). Pain and dysfunction were recorded using a 10-cm visual analog scale (VAS) ranging from a 0 value, representing no subjective sensation of pain/dysfunction to a 10 value, representing the worst imaginable pain/dysfunction. All assessments and recordings were carried out by one evaluator pretreatment and afterwards at each time point prior to any repeat injection. Only non-responders to the PRF injection(s) received further interventions, such as arthroscopic lysis and lavage or open surgery. Liquid platelet-rich fibrin preparation Blood was collected from the antecubital vein through an aseptic technique of blood collection, using commercially-available butterfly needle sets and vacutainer Table 1. Wilkes’ classification system for internal derangement of TMJ [31]. Stage Clinical findings Radiographic findings I Painless clicking, No locking Slight forward displacement, good anatomical contour of disc and passive incoordination demonstrable II Occasional painful clicking, Slight forward displacement, slight intermittent locking, thickening of posterior edge of headaches disc III Frequent pain, joint Anterior displacement with tenderness, locking, significant anatomical restricted motion deformity/prolapse of disc IV Chronic pain, headaches, Increase in severity, moderate restricted motion with degenerative remodeling hardcrepitus tissue changes V Variable pain, joint crepitus Anterior displacement, perforation with simultaneous filling of upper and lower compartments, filling defects. tubes (sterile uncoated plastic tubes) without additive (9-mL i-PRF tubes, Process for PRF, Nice, France) and immediately centrifuged. The low speed centrifugation protocol used to obtain liquid PRF was 60 (g) for 3 min [25]. (Table 2). For liquid PRF, only two layers are obtained after centrifugation: the red blood cells at the bottom and the liquid PRF at the top of the tube, with an approximate relation of 7:2, respectively. For each TMJ, 1.5–2 cc of liquid PRF was withdrawn into a 3 mL or 5mL syringe using a 21G needle by carefully penetrating the rubber top on the vacutainer tube (Figure 3). Injection technique All injections were performed by the same oral and maxillofacial surgeon (JBA). The skin surface of the preauricular region was disinfected with antiseptic solution, and a reference line was traced between the lateral canthus and tragus. An auriculotemporal nerve block was performed with 0.5–1.0 cc of 3% mepivacaine. The articular fossa (AF) as the point of injection was confirmed by manual palpation of its lateral edge (deepest concavity), about 10 mm anterior to the tragus and 2 mm below the canthal-tragal line [32]. A 30G needle was inserted in the TMJ capsule, 1.5-mL of liquid PRF was deposited into the superior joint space (SJS), and 0.5 mL was distributed in the retrodiscal tissue (RT) and pericapsular area (maximum of 2 mL/joint). The correct location of the needle was verified by confirming the ensuing ipsilateral open bite caused by the joint insufflation [33,34]. After the first injection, patients were interrogated and self-evaluated their pain/dysfunction progress every two weeks on a VAS. The protocol was continued only if there was a positive response (Responders) in comparison to the previously recorded values for pain on the VAS and was repeated until the pain-VAS value was zero (0) or reached a subjectivelydetermined satisfactory level. For patients who did not respond favorably to the treatment (Non-responders), the protocol was immediately discontinued (Figures 4 and 5). Statistical analysis Patients’ VAS results were averaged (mean ± SD). The mean values of the pain and dysfunction scores obtained at each time point were statistically compared to the preinjection value. All statistical analyses, tables, and figures Table 2. Low-speed centrifugation protocol for liquid platelet-rich fibrin (PRF). PRF protocol Liquid matrix Rotation (rpm) 700 Time of centrifugation (min) 3 (g)-force 60 Tubes Plastic Radius-Max (mm) 110 Centrifuge machine Duo centrifuge ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE 5 Figure 3. The yellow liquid-layer fraction represents the liquid platelet-rich fibrin (PRF) after centrifugation. 1.5–2 cc of liquid PRF was withdrawn into a 3-mL syringe without manipulating the red blood cell fraction. were graphed using Prism Version 6 (GraphPad Software Inc., La Jolla, CA, USA). Data are expressed as mean ± standard deviation. The significance of differences among means of data were analyzed using two-way analysis of variance (ANOVA) and a Tukey’s multiple comparison post-hoc test. Thereby, statistical differences were marked as significant if p-values were less than 0.05 (*p < 0.05), and highly significant if p-values were less than 0.01 (**p < 0.01) or 0.001 (***p < 0.001). Results The study sample consisted of 48 TMJs in 37 patients, with a female to male ratio of 5.2:1. Thirty-three TMJs (69%) showed improvement to liquid PRF injections (Responders). Fifteen TMJs (31%) did not respond to the treatment (Non-responders) (Figure 6, 7, and 8). Among the Non-responders, 11/15 TMJs required invasive surgery. When all 48 TMJ samples were analyzed, no statistically significant improvement in pain, dysfunction, or maximal mouth opening (MMO) could be determined, although notably favorable trends for all these variables were observed (Table 3). However, when Responders were analyzed, statistically significant reductions in pain scores were noted at 8 weeks, and at 3, 6, and 12 months; dysfunction and MMO also showed highly favorable trends (Table 4). The mean number of injections required to obtain a 0 or a satisfactory value of pain in the VAS according to the Wilkes’ classification were: stage II 3.16 ± 0.98; stage III 2.5 ± 0.70; stage IV 2.75 ± 1.13, and stage V 3.3 ± 1.56 (Figure 9). Twenty-six patients were treated unilaterally (70%) and 11 bilaterally (30%). There were no injection-related complications reported throughout the study. Eight TMJs (17%) had failed prior treatment of different types, and seven of those TMJs responded positively to liquid PRF injections (arthroscopy = 5 TMJs, corticosteroid injection = 2 TMJs). In relation to the pathological status of the TMJ derangement, 59% of TMJs treated were Wilkes intermediate-late or late stage (stages IV and V), and 6 J. B. ALBILIA ET AL. Figure 4. Injectable platelet-rich fibrin (i-PRF) injection protocol for TMJ derangement. Patients were interrogated before initiating the treatment protocol and before each injection. The visual analog scale (VAS) was used to register subjective sensation of pain and dysfunction (scale: no pain: 0; worst imaginable pain: 10). Treatment was continued only when the patients responded positively (responders) and was discontinued when higher VAS values were recorded (non-responders). Figure 5. Injection technique. An imaginary line (yellow) from the tragus to the lateral canthus and the manual palpation of the deepest concavity of the articular fossa (AF) guide the clinician to the site of injection. Liquid platelet-rich fibrin (PRF) is infiltrated into the superior joint space (SJS), the retrodiscal tissue (RT), and the pericapsular area. these responded the best to the tested treatment (78.5% and 100%, respectively) (Table 5). In four different patients, it was not possible to determine the stage of the internal derangement, due to ambiguous clinical symptoms and the absence of MRI. Discussion The non-surgical management of pain and dysfunction of TMJ derangements has been effective in improving the quality of life of many patients but inefficient in providing a treatment to stop or reverse the cycle of deterioration of the TMJ structures, and hence, explains the diversity of drugs available. Regenerative therapeutics are encompassed by the term biosupplementation, and this group of therapeutics aims to restore normal structure and function above and beyond symptomatic relief [35]. The objective of this preliminary investigation was to test a new autologous therapeutic protocol for painful TMJ internal derangement. A treatment protocol is proposed, consisting of intraarticular injections of liquid PRF every two weeks, provided the patient continues to report improvement (Figure 4). This shorter interval, compared ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE 7 Figure 6. Mean values recorded from all patients using the visual analog scale (VAS) for pain evaluation and maximal mouth opening (MMO) to evaluate dysfunction progression. Follow-up appointments are expressed in weeks (W) and months (M). Figure 7. Mean values recorded from all patients using the visual analog scale (VAS) for pain evaluation during follow-up in the Responder’s group. to two to four weeks, as reported by authors using PRP [17,36–38], aims at benefiting from the cumulative physiological effects from the precedent blood concentrate injection(s). Understanding the cycle of deterioration has led researchers to study not only the biomechanics of the TMJ but also the biochemistry involved in the pathophysiology of arthralgia and joint inflammation. The lack of waste removal and blood supply generates a higher concentration of pain mediators (substance P [SP], serotonin, bradykinin, leukotriene B4 [LTB4], and prostaglandin E2 [PGE2]) and pro-inflammatory cytokines (interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6 and IL-8) within the SF, which in chorus, results in vasodilation, extravasation, activation of immune cell–cell communication and differentiation, chemotaxis, and activation of nociceptive neurons [8,11,39]. The chronic presence of pain mediators and pro-inflammatory cytokines has been related to bone remodeling as well as to proteoglycan degradation, impairing cartilage elasticity [6,40]. There are two groups of patients in this study: “Responders” to the treatment and “Non-responders.” A rapid positive response in the “Responders” was observed as early as five days after the first and subsequent injections (69%). This suggests that PRF requires several days for its positive physiological effects to take place. This can be explained by liquid PRF’s spontaneous clotting (± 15 min) (Figure 10), which preserves its contents (cells and growth factors) in the articular space for a prolonged release [24]. This benefit generates a progressive return of functional activity and reduction in pain, due to restoration of the TMJ bio-environment. The slow release of growth 8 J. B. ALBILIA ET AL. Figure 8. Mean values recorded from all patients using the visual analog scale (VAS) for pain evaluation during follow-up in the non-responder’s group. Table 3. Pain, dysfunction and MMO in all samples expressed as Mean ± SD (statistical significance when p-value < 0.05). Pain score (VAS 1–10) 0W 2W 4W 8W 3M 6M 9M 12 M Mean ± SD 5.67 ± 2.47 3.62 ± 2.41 3.2 ± 2.57 2.90 ± 2.99 3.28 ± 3.17 2.40 ± 2.99 2.98 ± 3.13 1.73 ± 3.13 MMO (0–50 cm) Dysfunction (VAS 1–10) p-value* p > 0.05 (0.2967) p > 0.05(0.1302) p > 0.05 (0.1044) p > 0.05 (0.3912) p > 0.05 (0.0695) p > 0.05 (0.6326) p > 0.05 (0.1992) Mean 5.26 ± 2.70 4.22 ± 2.80 3.46 ± 3.08 3.06 ± 3.40 3.87 ± 3.49 2.57 ± 3.08 2.31 ± 3.28 1.63 ± 3.08 p-value* p > 0.05 (0.9532) p > 0.05 (0.5564) p > 0.05 (0.445) p > 0.05 (0.9229) p > 0.05 (0.2719) p > 0.05 (0.5218) p > 0.05 (0.3031) Mean 32.11 ± 7.47 33.68 ± 7.74 33.86 ± 7.76 33.5 ± 7. 81 33.07 ± 7.10 33.37 ± 6.80 35.2 ± 4.32 39.4 ± 6.35 p-value* p p p p p p p > > > > > > > 0.05 0.05 0.05 0.05 0.05 0.05 0.05 (0.8985) (0.8554) (0.9602) (0.9977) (0.9839) (0.8284) (0.0142) SD, standard deviation; MMO, maximal mouth opening; W, weeks; M, months; VAS, visual analog scale. Table 4. Pain, dysfunction and MMO among responders expressed as mean ± SD (statistical significance when p-value < 0.05). Time Pain score (VAS 0–10) 0W 2W 4W 8W 3M 6M 9M 12 M Mean 5.65 ± 2.58 3.09 ± 2.09 2.65 ± 2.14 1.71 ± 2.20 1.55 ± 1.49 0.51 ± 0.61 2.63 ± 3.36 0.76 ± 1.21 Dysfunction (VAS 0–10) p-value* p > 0.05(0.1814) p > 0.05(0.0749) p < 0.01(0.0084) p < 0.05(0.0253) p < 0.01(0.0019) p > 0.05(0.6171) p < 0.05(0.0454) Mean 5.33 ± 2.64 4.03 ± 2.79 2.93 ± 2.84 1.92 ± 2.59 2.37 ± 2.95 0.76 ± 1.19 1.96 ± 3.74 0.65 ± 0.93 p-value* p > 0.05(0.923) p > 0.05(0.3222) p > 0.05(0.0642) p > 0.05(0.3188) p < 0.05(0.0124) p > 0.05(0.4896) p > 0.05(0.0731) MMO (0–50 cm) Mean 33.18 ± 6.53 34.75 ± 7.13 35.12 ± 7.69 34 ± 7.53 33.73 ± 6.36 33.73 ± 6.36 35.2 ± 4.32 39 ± 8.71 p-value* p p p p p p p > > > > > > > 0.05(0.9129) 0.05(0.8137) 0.05(0.9988) 0.05(0.9999) 0.05(0.9999) 0.05(0.9726) 0.05(0.2713) SD, standard deviation; MMO, maximal mouth opening; W, week(s); M, months; VAS, visual analog scale. factors from solid PRF matrices was previously demonstrated in vitro [23]. In addition, it is noteworthy that Responders showed a sustained reduction in pain and dysfunction up to 12 months (Figure 7) and beyond (observed but not reported), further supporting the likelihood that liquid PRF possesses the ability to restore joint homeostasis. The results of this investigation are comparable to those applying PRP to the TMJ [17,32,41,42], but without an arthroscopic intervention. It is thus plausible to believe that in some patients, liquid PRF (produced by the LSCC) can induce a natural lavage of SF by its immediate delivery of immune cells for debridement [24] of joint debris and repair (neutrophilic granulocytes) following restitution of the synovium’s capillary network [43–45]. Non-responders (31%) showed an overall early improvement that was not sustainable beyond eight weeks, as seen in (Figure 8), and in some cases, invasive treatment was the alternative (11/48 TMJs required arthroscopic or open surgical interventions). Although some of these Non-responders may have improved ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE 9 Figure 9. Mean number of injections required to reach a zero or satisfactory pain level. The pathological condition of the participants was scaled using the Wilke’s classification [I–IV]. Table 5. Response to treatment based on Wilkes’ classification. Wilkes’ classification I II III IV V Undet. Responders (%) Non-responders (%) 0% 6 (47%) 2 (33%) 11 (78.5%) 10 (100%) 4 (100%) 1 (100%) 7 (53%) 4 (67%) 3 (21.5%) 0% 0% spontaneously at a later follow-up, this could not be attributed to the proposed therapeutic effects of liquid PRF. As such, Non-responders with similar signs and symptoms as at the pre-injection time point were offered conventional surgical treatment as soon as their Non-responder status was determined. It is important to note that no adverse effects or acute negative responses were recorded during or after liquid PRF injections throughout the study. Patients either improved or remained status quo as to their pain and dysfunction scores. No complications were observed related to blood immunology reactions or pain exacerbation. Among Responders, pain improvement during treatment appears to be correlated with the severity of the pathology. The higher the stage, the greater the number of liquid PRF injections were needed to reach the study goals in Wilkes’ stages III– V patients (Figure 9). If a patient missed a follow-up appointment, they returned with increased pain, but not with a VAS pain score as high as at the initial evaluation, in which case, treatment was continued. Although not statistically significant, it is noteworthy that MMO was inversely proportional to pain and dysfunction values (Figure 6). It is generally accepted that there are two categories of patients with TMJ internal derangement (ID): those Figure 10. Spontaneous (physiological) coagulation of liquid platelet-rich fibrin (PRF) (working time of 10–15 min). who adapt and those who do not adapt to the ID. The patients who show adaptive remodeling to the ID will progress to Wilkes’ IV or even V, without major symptoms in the initial stages. It is noteworthy that the best Responders to liquid PRF injections were TMJ derangements Wilkes’ IV (78.5%) and Wilkes’ V (100%), compared to 0–47% for cases Wilkes’ I–III. This suggests that patients who have the capacity to adapt to the different stages of ID may benefit the most from local administration of therapeutics, including liquid PRF. This finding is consistent with that of other minimally invasive interventions (such as arthroscopy, PRP, HA), being highly beneficial in patients with Wilkes’ IV–V ID [46–49], treatments that essentially modify the bio-environment of the joint and allow the body’s immune and repair mechanisms to take over. The benefits of intraarticular injections of liquid PRF appear to result from a combination of its cellular, biochemical, and angiogenic properties [50]. Hypotheses are as follows: first, that each PRF injection is causing a mechanical tear of adhesions through a hydraulic distension and expansion of the superior articular space, thereby eliminating the vacuum effect present in 10 J. B. ALBILIA ET AL. osteoarthritis (OA); and second, that the physiologically coagulated PRF improves SF viscosity and nutrition of the intracapsular structures [51,52] (Figure 10). The prolonged release of cytokines and growth factors (IL-1β, IL8, IL-4, VEGF, EGF, TGF-β1 and PDGF-AB [53]) plays an important role in providing a supportive environment for debridement by circulating macrophages and type A synoviocytes, followed by repair by chondrocytes and type B synoviocytes, as precursors to these cell types have been shown to be highly responsive to PRF [54,55]. Only now, following a shift from a catabolic state to an anabolic state, can remodeling of damaged synovial, cartilage, and bone surfaces (condylar lipping, osteophyte formation, subchondral cyst formation, irregular articular surfaces) occur [6,56]. Previous studies have associated IL-1β, TNF-α, IL-6 and IL-8 with pain and TMJ ID [57–59]. The high concentration of IL-4, an anti-inflammatory cytokine found in PRF, modulates inflammation by inhibiting MMP 1–3 and neutralizing all transduction pathways from IL-1β, TNF-α and prostaglandins [60] (Figure 11). Many clinical studies have reported the use of a single drug to treat TMJ internal disorders [1,9]. Although the combination of injectable therapeutics together with adjunctive therapy was described to provide improved benefits, the synergy requires further research [61,62]. In this study, patients were treated only with liquid PRF injections, irrespective of ongoing splint therapy. Additionally, study patients were not permitted to begin splint therapy, physical therapy, or other adjunctive therapies during the treatment and follow-up period. While external agents causing TMJ ID is outside the scope of this article, it is believed that the management of TMJ derangements should involve the management of external causes (extracapsular pathologies or systemic diseases) and internal causes (ID with or without OA) to achieve positive and long-lasting results. As such, a similar study taking into consideration adjunctive therapies, such as the wearing of an orthotic, concomitant, Botox injections to the elevator muscles, systemic antiinflammatories, or physical therapies, could be interesting insofar as determining the benefits of a combination therapy with liquid PRF injections. The strength of this preliminary investigation is limited, due to the absence of a control group using commonly accepted therapies or using normal saline. The regenerative capabilities of PRF require validation involving a higher number of patients, imaging follow-up, arthroscopic views, as well as preclinical animal models of OA with histopathologic analysis to further understand the Figure 11. The benefits of liquid platelet-rich fibrin (PRF) as a therapeutic agent for painful synovial joints. ® CRANIO : THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE mechanism of regeneration related to the use of PRF. Further studies are underway to reproduce and validate the long-term findings and to test various PRF matrices as a carrier for various therapeutics specifically to joints. [6] Conclusion This preliminary investigation demonstrates that intraarticular injections of liquid PRF appear to have significant analgesic effects lasting over 12 months in patients with localized painful internal derangement of the TMJ, which is only one of many synovial joint disorders. Although the results herein are preliminary (absence of a control group), patients suffering from Wilkes’ stage IV (intermediate-late) and stage V (late) respond the best to this specific second-generation blood concentrate. Patients with pain and dysfunction related to Wilkes’ stages I-III are better managed using conventional methods, such as arthroscopic or open surgical interventions, in order to treat the mechanical anomaly or diseased tissue in cases where nonsurgical methods have proven ineffective. [7] [8] [9] [10] [11] Funding This study was only partially funded, after completion of study, by the Research and Development Department of the Canada Revenu Agency. [12] Conflict of interest [13] No authors, except Joseph Choukroun, possess financial interest in Process for PRF®, Nice, France. This study was not funded or supported by Process for PRF® in any way. [14] References [1] Sharma A, Rana AS, Jain G, et al. 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