Alloplastic temporomandibular joint replacement: present status and future perspectives of the elements of embodiment

Medical device embodiment involves the following elements: materials, design, and manufacturing. Failure of any one of these elements can result in failure of the device, despite the others being satisfactory. The abundance of clinical and basic science literature published since 1986, demonstrates the safety and efficacy of alloplastic temporomandibular joint replacement (TMJR). Currently, there are 19 countries producing 41 TMJR devices. More than 75% are custom designed, and 27% are additively manufactured. In light of the increasing number of TMJR devices being designed and manufactured around the world, this paper will discuss TMJR embodiment so that clinicians understand their present status as well as the prospects for the future of new and/or improved TMJR devices, to ensure that these devices continue to be safe and effective long-term surgical options for the management of end-stage TMJ pathologies.     

Biomechanical simulation of temporomandibular joint replacement (TMJR) devices: a scoping review of the finite element method

The aim of this study was to perform a literature review on the use of finite element modeling (FEM) for the evaluation of the biomechanical behavior of temporomandibular joint replacement (TMJR) devices. An electronic search of online medical and scientific literature database was conducted using selected search terms. The search identified 307 studies, of which 19 were considered relevant to this study. Of the 19 selected studies, 10 (52.6%) investigated the influence of geometry and fixation methods, while two (10.5%) evaluated the behavior of artificial condyle–fossa structures. The TMJR devices assessed in these studies included TMJ Inc. (aka Christensen; 63.2%), Zimmer Biomet (15.7%), Stryker (10.5%), and a theoretical intramedullary condylar component (5.3%); 26.3% of the studies evaluated custom TMJR devices. Such studies provided important data on the distribution of strain and stress through TMJR structural components and surrounding bone by using different software systems and methods. The mean stress values were lower on a custom TMJR condyle–ramus component and the supporting bone than on the stock device. FEM proved to be an accurate and valuable biomechanical simulation tool for studying the current TMJR devices and should be considered a useful tool for the improvement and development of future joint replacement devices.     

Is the risk of chronic pain after total temporomandibular joint replacement independent of its indications? A prospective cohort study

Chronic pain is a possible long-term complication after alloplastic temporomandibular joint reconstruction (TMJR). This study was developed to evaluate various subjective and objective measurements to determine the presence and degree of TMJ pain in patients treated with TMJR regardless of the indication for the operation. A prospective, single-centre study was performed. Data on 36 patients (56 TMJR) were collected preoperatively and at follow up two to three years postoperatively. The primary outcome variable was subjective TMJ pain (none/mild, moderate/severe) at follow up. The predictor variables were objective pressure pain thresholds (PPTs) at the ipsilateral joint(s) and muscle(s), functional parameters (incisal range of motion, maximum voluntary clenching), subjective oral health-related quality of life (OHRQoL), and demographic and surgical variables. The number of patients with moderate/severe pain decreased from 17 preoperatively to 10 at follow up. Self-reported TMJ pain was significantly reduced in the entire group (p = 0.001). Patients with moderate/severe pain at follow up were more restricted in their OHRQoL but did not differ in PPT and functional parameters from the no/mild pain group. Moderate/severe TMJ pain at follow up was associated with unilateral TMJR and more preoperative pain. This study provides preliminary evidence that despite good pain reduction in most patients, persistent pain after TMJR is common and, in rare cases, may even worsen regardless of the original diagnosis. At follow up there was a close relation between OHRQoL and TMJ pain. TMJ pain after TMJR cannot be confirmed by objective measurement methods (PPTs and functional parameters).     

Reasons for failure of total temporomandibular joint replacement: a systematic review and meta-analysis

The aim of this study was to evaluate the revision rate after total alloplastic temporomandibular joint replacement (TMJR) and determine whether there is a higher risk of revision surgery with stock or custom-fitted prostheses (the two most current TMJR prosthesis types). A systematic review was performed, with a search of PubMed, Google Scholar, and the Cochrane Library in November 2020. Overall, 27 articles were included in this study, describing Biomet and TMJ Concepts prostheses and including postoperative data on complications requiring a return to the operating room. A total of 2247 prostheses were analysed: 1350 stock Biomet prostheses and 897 custom-fitted TMJ Concepts and custom-fitted Biomet prostheses. The global revision rate was 1.19 per 100 prosthesis-years. The most common reason for revision was heterotopic bone formation. Stock prostheses appeared to have a lower risk of revision compared to custom prostheses: rate ratio 0.52 (95% confidence interval 0.33–0.81, P-value 0.003). Regarding causes of revision, the only significant difference between the types of devices was a higher rate of heterotopic bone formation for custom-made prostheses (P = 0.001). The results of this study revealed a low revision rate post TMJR revision, with stock devices even less prone to such risk. Nevertheless, these results can be explained by the fact that custom-made prostheses are more likely to be used for cases in which the anatomy is significantly abnormal or there is a history of multiple joint surgeries, which carry a greater risk of complications and heterotopic bone formation.     

Maximum voluntary bite force in patients with alloplastic total TMJ replacement – A prospective study

Alloplastic temporomandibular total joint replacement (TJR) for end-stage disease, congenital disorders and following ablative oncological surgery has been shown to reduce pain and improve function. The purpose was to assess the maximum voluntary bite force and maximum interincisal opening (MIO) in patients undergoing alloplastic total temporomandibular joint replacement (TJR).Seventeen patients with different diagnoses resulting in condylar hypomobility (8 patients; 15 joints) and condylar instability (9 patients; 12 joints) had undergone alloplastic TMJ reconstruction. Maximum voluntary bite force and MIO were measured at pre-operatively (T0), 2 (T1), 6 (T2) and 12 (T3) months. For ordinal data comparison at different time-points, the Wilcoxon signed-ranks test was used.There was a significant improvement in maximum voluntary bite force for both, patients with condylar hypomobility (P = 0.003) and condylar instability (P = 0.007). Analysis of MIO revealed a significant improvement at T3 (P = 0.002).Alloplastic TJR would appear to increase maximum voluntary bite force and MIO. Biomechanical integrity of the stomatognathic system and the ability of the patient to triturate food could be improved by alloplastic temporomandibular joint (TMJ) replacement.     

Idiopathic condylar resorption. Report of a case

Idiopathic condylar resorption, progressive resorption of the mandibular condyles, is discussed. A case treated with alloplastic total temporomandibular joint replacement devices is presented. The case report includes six-year follow-up. The patient's mandibular retrusion, anterior open bite, malocclusion and totally resorbed mandibular condyles were successfully treated in a single-stage operation with alloplastic total temporomandibular joint replacement devices     

Analysis of mandibular motion following unilateral and bilateral alloplastic TMJ reconstruction

The purpose of this study was to analyse the masticatory patterns and range of motion (maximal incisal opening (MIO), protrusion and lateral excursion) in patients who have had unilateral and bilateral temporomandibular joint (TMJ) replacement with an alloplastic prosthesis, and compare them to each other and to normal controls. Mandibular motion was examined in 18 patients, who had undergone alloplastic TMJ reconstruction, 13 with a bilateral prosthesis and 5 with a unilateral prosthesis, and in 13 normal controls. A statistically significant difference (P < 0.01) for MIO and maximum lateral excursion was observed between the bilateral group and the control group. Maximum protrusion was only statistically significantly different (P < 0.05) between the bilateral group and the control group. For the unilateral group, a statistically significant difference (P < 0.01) was seen only with maximum contralateral excursion when compared with controls. No statistically significant difference existed in MIO and protrusion between the unilateral and bilateral groups. Even though maximum ipsilateral lateral excursion was greater for the unilateral group than either left or right maximum lateral excursion by the bilateral group, this difference was not statistically significant. This study provided an in vivo analysis of mandibular motion following alloplastic TMJ reconstruction.     

Total temporomandibular joint replacement: A clinical case with a proposal for post-surgical rehabilitation

OBJECTIVE: The literature on total alloplastic temporomandibular joint (TMJ) reconstructions is encouraging, and studies on total alloplastic TMJ replacements' outcomes showed acceptable improvements in terms of both pain levels and jaw function. Nevertheless, a better standardization of both surgical and post-surgical phases should further improve the efficacy of treatment. MATERIALS AND METHODS: The case report describes the surgical and post-surgical phases of treatment in a patient who underwent a total unilateral joint replacement for TMJ ankylosis, along with a proposal for a post-surgical rehabilitation protocol providing strong passive and active physiotherapy and hyaluronic acid injections to the contralateral joint. RESULTS: The post-operative (PO) course was uneventful. The patient showed a marked improvement up to about 60% in mouth opening and had no pain on either side at the 1-year follow-up. CONCLUSION: In a patient with unilateral TMJ ankylosis, total TMJ replacement was successful. A carefully tailored post-surgical rehabilitation protocol helped the patient to gain a clinically significant improvement in jaw function. Longer follow-up periods are needed to assess the long-term maintenance of results. Clinical trials are strongly recommended to assess the relative efficacy of different PO protocols.     

The autogenous dermal graft in temporomandibular joint disc surgery

Repair or replacement of the disc in 58 patients (64 joints) with temporomandibular joint internal derangement was done using an autogenous dermal graft. Long-term follow-up of 3 to 8 years revealed successful elimination of symptoms and restoration of mandibular function in 51 patients (87.9%). The autogenous dermal graft, rather than alloplastic materials, may be the procedure of choice when repair or replacement of the temporomandibular joint disc is indicated.     

Temporomandibular joint ankylosis: a review of 44 cases

Introduction

Mandibular hypomobility may arise due to a wide variety of intraarticular as well as extraarticular disorders in the temporomandibular joint region. Temporomandibular joint ankylosis causes a variable restriction in jaw mobility. This study presents a broad overview of the management of temporomandibular joint ankylosis at the Department of Oral and Maxillofacial Surgery, GGSM Subharti Dental College, Meerut, Uttar Pradesh, India.

Materials and methods

Between May 2002 and September 2005, a total of 44 patients underwent surgical release of temporomandibular joint ankylosis. This study is a retrospective analysis of the patient population characteristics and the surgical procedures employed.

Results and discussion

The patients have completed a follow-up of 24 to 64 months (median, 38.5 months). Of the 44 patients, 12 had bilateral involvement. Trauma in childhood was, expectedly, the most frequent etiologic factor. Gap arthroplasty was the most frequently employed technique, followed by the use of autologous tissue interposition. The temporalis muscle-fascia and the temporalis fascia alone, as well as the auricular cartilage, were employed most frequently. Complete alloplastic condylar replacement was performed in one patient, who, unfortunately, returned with pain, clicking, and deviation of the jaw, necessitating removal within 1 month. Total joint replacement was abandoned after this case. We outline our protocol for the management of this disabling condition.     

Total alloplastic temporomandibular joint replacement: the Czech-Slovak initial experience

In 2004, total alloplastic temporomandibular joint (TMJ) replacement began in the Czech Republic and Slovakia. This paper presents initial subjective and objective data compiled between 2005 and 2009 from those cases. Data were collected from 27 patients (38 joints) reconstructed with the Biomet-Lorenz stock and custom TMJ prostheses during a mean follow-up period of 24 months. The variables of pain and mouth opening were evaluated pre- and postoperatively. Patients classified pain on a scale of 0-5 (none - unbearable). The extent of opening was investigated by a physician (the distance between the points of the incisors on the upper and lower jaw was measured). The most common indication for replacement was ankylosis. There was an improvement in pain score in 15 patients. 4 patients reported worsening of pain and 8 patients did not complain of pre- or postoperative pain. Mandibular opening increased from a mean of 17.7 mm preoperatively to a mean of 29.1mm postoperatively. There were complications related to the surgery, but no significant complications related to the devices. Total alloplastic TMJ replacement appears to be a safe and effective method of reconstruction in the patients in this initial study.     

标准型人工颞下颌关节置换术应用效果初步报告

目的:介绍标准型人工全关节置换术应用于颞下颌关节重建的方法,初步评价其疗效及应用价值。方法:6例(10侧)颞下颌关节病患者,年龄49～66岁,平均59岁。3例(5侧)有既往颞下颌关节手术治疗史,3例(5侧)为内紊乱伴骨关节炎。术前均有明显开口受限及关节区疼痛,开口度1.0～2.9cm,平均1.9cm。采用标准型人工关节置换术,术后定期观察开口度及关节疼痛等变化,结合影像学检查等评价治疗效果。结果:成功完成6例(10侧)人工关节置换术。术后随访7～49个月,平均17.5个月。植入关节未出现因感染、排异、松动或断裂等导致的失败。有既往手术的病例中,1例(2侧)发生假体内侧异位成骨,1例(2侧)耳颞区疼痛无法缓解,其余4例(6侧)开口受限及关节区疼痛均有较明显改善。影像学检查均未见假体松动等异常情况。结论:标准型人工全关节置换术对缓解关节疼痛有明显效果,可有效改善开口度及提高咀嚼能力,但对咀嚼肌疼痛的缓解效果不理想。     

Quality of life,chronic pain,insomnia, and jaw malfunction in patients after alloplastic temporomandibular joint replacement: a questionnaire-based pilot study

Studies of patients undergoing alloplastic total temporomandibular joint replacement seldom report on quality of life (QoL) and sleep. The aim of this pilot study was to assess these factors in such a patient cohort using validated psychometric questionnaires. Data were collected via online surveys comprising the following six questionnaires: Short Form-12 Health Survey (SF-12), Patient Health Questionnaire-15, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30, Insomnia Severity Index, Graded Chronic Pain Scale, and Jaw Disability List. Pain intensity, limitation in nutrition, and treatment satisfaction were assessed using numerical rating scales. Mouth opening was measured at follow-up. The SF-12 Physical Composite Score was markedly lower than that of the age-matched general population, whereas the Mental Composite Score did not differ significantly. Participants indicated a low somatization level and low level of disability due to pain, but reduced QoL. Clinically relevant insomnia was reported by 36% of participants. In conclusion, the results of this pilot study indicate that QoL and sleep in patients with a total temporomandibular joint replacement differ from those in the general population, indicating the need for a comprehensive outcome assessment utilizing validated psychometric tools in accordance with the current biopsychosocial model of chronic disorders.     

Novel approach to the study of jaw kinematics in an alloplastic TMJ reconstruction

Total alloplastic temporomandibular joint (TMJ) reconstruction is a reliable treatment modality in patients with severely diseased TMJ with good clinical behaviour. TMJ mandibular function after alloplastic reconstruction has scarcely been analysed as a biomechanical parameter and investigation has generally been limited to interincisal measurements without deeper insight into joint kinematics. Dynamic stereometry to assess condylar movements relative to the fossa was performed at the 5 year follow-up of a patient who underwent condylar resection of the right TMJ followed by total alloplastic joint reconstruction to treat pigmented villonodular synovitis. The patient could achieve wide mouth opening, but overall mandibular kinematics showed a strong deviation towards the prosthetic side due to the lack of mandibular translation caused by the absence of the lateral pterygoid attachment. Possible overloading of the joint contralateral to the TMJ prosthesis might be prevented by optimizing replacement joint design.     

The healthcare burden and associated adverse events from total alloplastic temporomandibular joint replacement: a national United States perspective

The purpose of this study was to provide a United States perspective on alloplastic total joint replacement. We sought to estimate the inpatient burden and report the most common adverse events using two administrative datasets. The National Inpatient Sample was queried from October 2015 to December 2016 for total joint replacement admissions using International Classification of Diseases 10^th revision codes, and the Manufacturer and User Facility Device Experience registry was queried from January 2009 to September 2019 using manufacturer brands. The combined final sample included 114 inpatient admissions and 392 adverse events. Mean age was 43.1 years, and most patients were white (82.7%) and female (86.0%). The mean hospital charge was $108,709.43 and the mean length of stay was 2.6 days. The most common adverse events were infection (26.3%), heterotopic bone (20.9%), and poor intraoperative fit (14.0%). Fifty-four percent of cases had bilateral total joint replacements, 24.6% had simultaneous subcutaneous abdominal fat grafting, and 11.4% had simultaneous maxillary repositioning. Fat grafting and maxillary repositioning were not associated with any significant difference in the length of stay or cost. Compared to unilateral cases, bilateral total joint replacements carried significantly greater charges (P < 0.01), but no increased length of stay (P = 0.70), suggesting that bilateral and unilateral cases may experience a similar postoperative course.     

Temporomandibular joint replacement: a New Zealand perspective

Alloplastic total temporomandibular joint replacement (TMJ TJR) has been performed in New Zealand utilizing the TMJ Concepts patient-fitted system since 2000. The data analysed in this study were collected retrospectively from questionnaires sent to all maxillofacial surgeons in New Zealand who had implanted TMJ Concepts devices between 2000 and 2011. A total of 63 devices were implanted in 42 patients (13 males, 29 females) during this 12-year period. The primary indication for TMJ TJR was end-stage joint disease resulting from ankylosis and arthritis. The mean age of the patients was 47 years (range 7–80 years). The most common complication reported was transient facial nerve impairment in 4.8% of the patients. Objective results, measured as the maximal incisional opening, improved by a mean of 17.3 mm (P < 0.01); 90% of patients reported improved quality of life. New Zealand oral and maxillofacial surgeons have concluded that TMJ TJR using the TMJ Concepts prosthesis is a reliable treatment option for the management of end-stage TMJ disease.     

Total temporomandibular joint replacement. Who? What? When? Where?

The temporomandibular joint, like other joints such as the hip and knee, can be affected by a number of conditions that may lead to joint failure, necessitating total joint replacement. The TMJ Implants, Inc., or Christensen alloplastic reconstruction prostheses, play an important role in the treatment of these conditions. Patients with severely degenerated and/or nonfunctioning joints who undergo reconstruction with the Christensen total joint replacement prosthesis experience an increase in quality of life similar to that experienced by orthopedic patients with total joint replacement of the knee or hip.     

Synovial entrapment in alloplastic temporomandibular joint replacement

Complications of alloplastic temporomandibular joint (TMJ) prostheses can lead to stress and anxiety for the patient and the surgical team, and prosthesis substitution is sometimes required. The aim of this case report is to describe the surgical finding of synovial entrapment with interposed fibrosis in a postoperative alloplastic TMJ revision, managed effectively with adequate surgical debridement. The authors believe that synovial entrapment needs to be considered as a possible postoperative complication of total joint replacement when no clear symptoms of infection, metal hypersensitivity, osteolysis, or heterotopic bone formation are present. The implications of synovial entrapment in TMJ alloplastic replacement remains relatively unpredictable and poorly understood.     

髁突置换治疗创伤性颞下颌关节强直五例

目的 总结用人工髁突置换治疗创伤性颞下颌关节强直(temporomandibular joint ankylosis,TMJA)的临床效果.方法 2006年8月至2008年4月北京大学口腔医学院·口腔医院口腔颌面外科共5例创伤性TMJA患者接受人工髁突置换手术,患者均为男性.术前行CT检查后,用快速成形技术制作三维头模,在头模上模拟切除关节骨球、关节成形、选择适宜的人工髁突,术中依术前设计安放并固定人工髁突.术后1周和复查时评价手术效果.结果 5例共植入6侧人工髁突(1例为双侧).3例复查时间为术后8～30个月,另外2例失访.复查时张口度平均为30 mm,2例咬合关系良好,1例前牙区有约1 mm的开骀.结论 人工髁突置换可以作为创伤性TMJA手术治疗的方法之一,其临床效果还需进一步验证.     

Management of recurrent ankylosis in arthrogryposis: new solutions to a rare problem

Arthrogryposis is a rare condition that comprises contracture of the joints, muscular weakness, and fibrosis. Restricted mouth opening caused by coronoid hyperplasia has been reported but to our knowledge, ankylosis of the temporomandibular joint (TMJ) has not. Standard management of ankylosis includes creation of a gap arthroplasty and possible reconstruction with autogenous or alloplastic materials. We describe management of a patient with arthrogryposis who developed ankylosis for a second time after satisfactory gap arthroplasty and total replacement of the TMJ with a custom-made prosthesis. The original prosthesis was removed, the ankylosis resected, and the prosthesis replaced. This has given an excellent outcome at 12 months.