Abstract
A previous randomized controlled trial (RCT) by Schiffman et al. (2007) compared four treatments strategies for temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock). In this parallel group RCT, 106 patients with magnetic resonance imaging (MRI)-confirmed TMJ closed lock were randomized between medical management, non-surgical rehabilitation, arthroscopic surgery, and arthroplasty. Surgical groups also received rehabilitation post-surgically. The current paper reassesses the effectiveness of these four treatment strategies using outcome measures recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS). Clinical assessments at baseline and at follow-up (3, 6, 12, 18, 24, and 60 months) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. TMJ MRIs were performed at baseline and 24 months, and TMJ tomograms at baseline, 24 and 60 months. Most IAOMS recommended outcome measures improved significantly over time ( P ≤ 0.0003). There was no difference between treatment strategies relative to any treatment outcome at any follow-up ( P ≥ 0.16). Patient self-assessment of treatment success correlated with their ability to eat, with pain-free opening ≥35 mm, and with reduced pain intensity. Given no difference between treatment strategies, non-surgical treatment should be employed for TMJ closed lock before considering surgery.
Dentists routinely provide patients with initial medical management for their temporomandibular disorders (TMD). When patients are refractory to medical management, triaging them for further care is challenging due to the lack of evidence-based guidelines. This is particularly true for patients with temporomandibular joint (TMJ) disc displacement without reduction and with limited opening ( i.e. , closed lock), a chronic, persistent disorder that can cause significant jaw pain, limited jaw movement, and functional impairment, affecting among other capacities, the ability to eat. This condition has been postulated to lead to TMJ degenerative joint disease (DJD).
Although case series involving surgical treatment of closed lock suggest that surgery could have better outcomes than non-surgical rehabilitation therapy, clinical trials to confirm such claims are limited. Reviews of the literature, including one meta-analysis, have not demonstrated any differences between physical therapy, arthrocentesis, arthroscopic surgery, and disc repair/repositioning surgery relative to outcomes such as maximum mouth opening, jaw pain, and jaw function. A more recent randomized clinical trial (RCT) comparing arthroscopy to open-joint surgery showed that both treatments were effective for symptomatic closed lock patients. Our 5-year RCT for patients with closed lock demonstrated that medical management and non-surgical rehabilitation improved pain and dysfunction as effectively as either arthroscopic surgery with rehabilitation, or arthroplasty (open joint surgery) with rehabilitation. Finally, the conclusion of the 2011 Cochrane Collaboration review on arthroscopy is that arthroscopy is less effective than open surgery for pain reduction at 12 months postoperatively. Arthroscopy is associated with greater improvement than arthrocentesis for maximum mouth opening at 12 months, and both arthroscopy and non-surgical treatments reduce pain at 6 months. This review states also that the study by Schiffman et al. is one of the best RCTs assessing the treatment for TMJ closed lock.
The current paper complements the 2007 report by Schiffman et al. in which treatment success was defined by two primary outcome study measures: the Symptom Severity Index (SSI) to assess TMJ pain, and the Craniomandibular Index (CMI) to assess jaw dysfunction. For this study, we used the International Association of Oral and Maxillofacial Surgeons (IAOMS) recommended criteria for success to assess the relative effectiveness of medical management, rehabilitation, arthroscopic surgery, and arthroplasty. This will allow for comparisons of the study outcomes with those of other studies using IAOMS recommended outcomes. In addition, this report compares these treatment strategies for a closed lock disorder relative to patient satisfaction, treatment costs, and selected radiographic outcomes, including TMJ disc status observed at 24 months and TMJ hard tissue status observed at 60 months post-treatment.
Patients and methods
Study design and study population
This parallel group RCT was conducted from June 1992 to June 2004. The sources of the study subjects, informed consent procedures, institutional review board (IRB) approval for conducting the study, the potential limitations of such a scientific inquiry, and the CONSORT checklist and flow-chart have been reported previously. We also received approval for this ongoing data analysis. The authors have read the Declaration of Helsinki and followed the guidelines for this investigation. Inclusion and exclusion criteria are summarized in Fig. 1 . The diagnosis of TMJ disc displacement without reduction ( i.e. , closed lock) was confirmed using TMJ magnetic resonance imaging (MRI). Other inclusion criteria included daily joint pain (arthralgia) affected by jaw function, replication of joint pain with palpation, and limited mouth opening. A concurrent diagnosis of masticatory myofascial pain was also allowed for these study patients.
Randomization and treatments
This RCT assessed four treatment strategies with each strategy labelled in terms of its initial treatment modality: (1) medical management, (2) rehabilitation, (3) arthroscopy with rehabilitation, and (4) arthroplasty with rehabilitation. These treatment strategies were designed to represent treatment choices occurring in clinical practice. The initial treatment randomization was concealed from patients and care provider(s) until the enrollment procedure was completed. The randomized allocation employed two strata: ‘non-chronic’ disorder (duration of limited mouth opening <6 months) and ‘chronic’ disorder (duration of limited mouth opening ≥6 months). This ensured that each group would be balanced with regard to chronicity of limited mouth opening.
The treatment strategy randomization also employed unequal blocks to increase the number of patients assigned to ‘medical management’ because we anticipated a priori that such requests would be greatest in this group. By design, we intended to honour requests by patients for a change in treatment just as occurs in actual clinical practice.
The four treatment strategies are described as follows and are described in more detail in the appendix of our prior manuscript. ‘Medical management’ included education about the patient’s condition, with optimistic counselling, a self-help programme, and a 6-day regimen of oral methylprednisolone followed by prescription non-steroidal anti-inflammatory drugs (NSAIDS) for up to 6 weeks. Although patient preference for specific NSAIDs was honoured, ibuprofen 800 mg three times daily was used most often. Initially, concurrent short-term use of a muscle relaxant was used as needed, and the medication was typically cyclobenzaprine, 10 mg at bedtime. After this course of medication management, over-the-counter analgesics were used as needed. All medications, including over-the-counter analgesics, were monitored at monthly appointments by one orofacial pain dentist (ELS), with the goal of minimizing unnecessary use of medications. Medical management was also provided to patients in the other three treatment groups.
The rehabilitation team included an orofacial pain dentist, a physical therapist, and a health psychologist. They implemented medical management as described above, plus an intraoral orthotic, physical therapy, and cognitive-behavioural therapy. Patients were randomly assigned to one of the two treating orofacial pain dentists (ELS, JRF) who inserted and monitored the use of an orthotic at monthly appointments for 6 months, and then as needed. Patients who continued to use an orthotic after the first 6 months were seen at least one time per year to monitor its effects. The orthotic typically had a flat plane design ( i.e. , stabilization splint). A registered physical therapist performed outcome-based physical therapy designed to decrease pain, increase function for eating and talking, and increase pain-free active range of motion. Mobilization of the jaw and modalities were used as indicated, combined with a home exercise programme. When active physical therapy was completed, the recorded improvements in pain and function were monitored monthly for 6 months, and then as needed. A licensed clinical psychologist implemented and monitored a cognitive-behavioural programme usually consisting of self-help and oral habit reversal techniques. Patients were typically seen three times by the clinical psychologist.
Arthroscopy consisted of a standardized procedure described by Moses and Poker that was performed by one of two participating oral surgeons (JQS or RBT) who were randomly assigned. Following general anaesthesia, the superior joint space was injected with bupivacaine and infused with heparinized lactated Ringer’s solution. After the needle was removed, a cannula was inserted at the same entry site, and a sharp trocar was used to puncture the joint capsule. A blunt trocar was then employed to enter the superior joint space and to lyse intracapsular adhesions. Debris and blood were cleared with Ringer’s solution using a secondary needle, as needed, as an outflow port for the irrigation. Betamethasone was then injected into the capsule, and the mandible was manually moved to maximize the patient’s range of motion.
Arthroplasty was an open joint surgery that was performed under general anaesthesia by Dr. Clyde Wilkes in accordance with his published protocol. Briefly, the goal was to do a disc repositioning procedure (discoplasty) when feasible. However, if the surgeon determined that a discoplasty was not indicated, a disc removal procedure ( i.e. , discectomy) was performed with joint debridement and hard tissue recontouring as needed. Intra-articular steroids were not used with any of the arthroplasties.
Patients were seen at least once per month over the first 6 months by the treating surgeons, and then as needed. All surgical patients saw the same physical therapists and the psychologist who treated the rehabilitation group. In addition, if an orthotic was judged to be indicated, then this was inserted postoperatively and monitored by one orofacial pain dentist (ELS), as described above.
Follow-up data collections
Clinical examinations and questionnaires were completed at baseline and at the 3-, 6-, 12-, 18-, 24-, and 60-month follow-ups. One examiner (PAL), who was blinded to treatment assignments, performed all clinical examinations. When patients presented for their clinical evaluation, a research coordinator administered questionnaires and reminded them not to discuss treatment with the examiner. Tape was placed over both pre-auricular areas to conceal the presence or absence of a surgical scar, and patients were paid $200 at each follow-up visit.
Radiographic data collections were based on imaging studies performed at Hennepin County Medical Centre, Minneapolis. Study patients received TMJ MRI at baseline and at their 24-month follow-up. TMJ tomogram studies were performed at baseline, 24 months and 60 months. A board-certified radiologist (QNA) did all imaging interpretations.
Fig. 2 lists the IAOMS recommended criteria for evaluating TMJ surgical treatment outcomes. Since the IAOMS did not provide operational definitions for these outcome measures, the measurement methods used in this data collection are explained below under ‘Data collection specifications’. This report also takes into consideration both jaw joint pain and jaw muscle pain. Two other important outcome measures defined under ‘Data collection specifications’ are patient satisfaction with their treatment, and treatment cost.
Data collection specifications
Pain outcomes
The IAOMS recommended pain intensity and frequency measures are subscales of the reliable and valid SSI. These data were available for analysis since the SSI was one of the primary outcome measures used in the initial report of this RCT. Given that IAOMS recommendations were for postoperative assessment of TMJ surgery, it is assumed that their recommended pain intensity and frequency measures were intended for assessment of pain in the TMJ. TMJ pain intensity was measured based on the question, “How intense is your usual level of jaw joint pain in the past month?” The response was assessed as a categorical measure on a 5-point scale: (1) no pain, (2) mild pain, (3) moderate pain, (4) severe pain, and (5) most pain imaginable. TMJ pain frequency was measured by six frequency categories including: (1) never, (2) once monthly, (3) once weekly, (4) once daily, (5) once hourly, and (6) constantly. Since muscle pain is also a frequent problem associated with TMJ closed lock, parallel questions were queried regarding jaw muscle pain intensity and frequency.
Jaw range of motion and TMJ sounds
The IAOMS recommended measures for jaw range of motion and TMJ sounds are components of the second primary outcome measure used in the initial report of this RCT, i.e. , the CMI. This is a reliable and valid instrument designed to globally assess TMD signs including TMJ pain, dysfunction, and joint sounds. Since the CMI operationalizes measurement of jaw range of motion (ROM) on a continuous scale (mm), our data were readily reanalyzed according to IAOMS recommendations. Maximum unassisted opening without pain was dichotomized as: no limitation (≥35 mm) and limitation (<35 mm). Lateral excursive movements and protrusive movements were categorized as: no limitation (≥6 mm) and limitation (<6 mm). TMJ sounds were assessed based on three repetitions of each jaw movement including opening, closing, right and left lateral excursion, and protrusion of the jaw. Joint noise response categories were measured separately for joint clicks and crepitus. Disc clicks were recorded in four categories: no click, or clicking occurring during 1, 2, or all 3 repetitions for each jaw movement. Crepitus sounds were recorded as none, fine crepitus, or coarse crepitus.
Mandibular function impairment
Mandibular function impairment was assessed using the question, “In general, when chewing foods, what types of foods cause pain in your jaw and/or jaw joint?” The response options included: (1) no pain when eating any foods, (2) pain only when eating chewy (resistant) foods, (3) pain when eating most foods, (4) pain even when eating soft foods, and (5) pain when eating anything. Per IAOMS recommendations requiring minimal inconvenience associated with eating, the ability to chew was dichotomized as 1 or 2 = acceptable, versus 3–5 = not acceptable.
Radiographic imaging assessments
Tomograms were scored according to four specified assessments evaluating changes in either shape or bone density that affected either the glenoid fossa or the condyle. Each item was scored as: 0 = normal; 1 = mild change; 2 = moderate change; 3 = severe change. Scores of 1 and 2 were considered as various stages of remodelling ( i.e. , sclerosis and/or flattening) and a score of 3 was considered frank DJD ( i.e. , osteophytes, subcortical cysts, generalized sclerosis, and surface erosion). The overall tomogram score for a given joint was based on the greatest score observed: 0 indicating that no score among the four assessments was greater than 0; 1 representing a worst score no greater than 2; and 2 representing a worst score of 3, i.e. , DJD. MRIs, performed at baseline and at 24 months, were scored regarding disc position with 1 = normal, 2 = a reducing disc, and 3 = a non-reducing disc. The radiologist’s intra-rater reliability for the interpretation of the TMJ tomograms and MRIs was assessed at baseline, mid-study, and at the study end, resulting in kappa values ranging from 0.88 to 0.93. The radiologist had no contact with patients and was blind to their treatment group assignment.
Satisfaction with the treatment
The Group Health Association of America (GHAA) Consumer Satisfaction Survey was employed to assess the patients’ satisfaction with their treatment outcome. Self-reported treatment outcomes included: (1) poor, (2) fair, (3) good, (4) very good, and (5) excellent. A finding of treatment success required a self-report of 4 or 5; scores of 1–3 were considered as less-than-optimum in this study. This survey was administered only at the 60-month follow-up visit and can be obtained from GHAA (Department of Research and Analysis, Group Health Association of America, Inc., 1129 Twentieth St. NW, Suite 600, Washington, DC 20036, USA).
Cost of treatment
The cost of treatment was determined after the 60-month follow-up by record reviews for all patients, including costs of orthotics, physical therapy modalities, and cognitive-behaviour treatments. The cost of the TMJ MRIs and tomograms were not included in the cost estimates since they were the same for all treatment strategies. Additional costs pertinent to surgical groups were the cost of unilateral or bilateral TMJ surgeries. Applicable surgery costs were also accounted to the medical management and comprehensive rehabilitation treatment strategies for any patient from one of these groups who opted for surgery at some time after the 3-month follow-up visit.
Statistical analyses
The analysis of data for this study was specified a priori as ‘intention-to-treat’, meaning that, for the primary analysis, all patient data would be analyzed according to each patient’s randomized initial treatment strategy assignment. Consequently, patients who requested a change in treatment modality (after their 3-month follow-up) were not reassigned to a different treatment for the analysis. Likewise, intention-to-treat studies, often referred to as effectiveness studies, commonly include in the final analysis the results of dropouts, i.e. , study participants who refuse their treatment and drop out of the study after learning of their randomized treatment allocation. The primary data analysis for this study includes the dropouts, while a secondary data analysis was also performed that was limited to those patients who received a study treatment. P -values were not adjusted for multiple comparisons.
Each IAOMS recommended outcome was measured at the beginning of the study and tested for differences between groups at baseline using Fisher’s exact test, as shown in Table 1 . Treatment success based on the IAOMS criteria shown in Fig. 2 was assessed for each patient’s data at each follow-up, with ‘success = yes’ if all conditions were satisfied and ‘success = no’ otherwise. Table 2 shows rates of success for each treatment strategy at each follow-up time, and Fisher’s exact test was used to test differences between these rates (see P -value for between-group differences).
