Simultaneous standard total joint prosthesis reconstruction with SSRO and Le Fort I osteotomy in the treatment of unilateral temporomandibular joint ankylosis with jaw deformity: a case cohort study.

OBJECTIVE: Unilateral temporomandibular joint ankylosis with jaw deformity (UTMJAJD) may require simultaneous total joint prosthesis (TJP) reconstruction, sagittal split ramus (SSRO), and Le Fort I osteotomies. The purpose of this study was to evaluate outcomes in patients treated with these procedures. METHODS: Patients diagnosed UTMJAJD between 2016 and 2018 were selected for the study. Mandible-first procedure was performed after ankylosis release with TJP on the ankylosed side and SSRO on the contralateral side. Le Fort I osteotomy with and without genioplasty was lastly performed. Maximal incisor opening (MIO), facial symmetry, and jaw and condyle stability were compared before, after operation, and during follow-ups. RESULTS: Seven patients were included in the study. Their average chin deviation was 9.5 ± 4.2 mm, and maxillary cant was 5.1 ± 3.0°. After operation, jaw deformity significantly improved, with chin deviation corrected 7.6 ± 4.1 mm (p = 0.015) and advanced 5.9 ± 2.5 mm (p = 0.006). After an average follow-up of 26.6 ± 17.1 months, MIO significantly increased from 11.4 ± 9.3 to 35.7 ± 2.6 mm (p = 0.000). The occlusion was stable with no significant positional or rotational changes of the jaw (p > 0.05). There was no obvious condylar resorption during follow-ups. CONCLUSION: Simultaneous TJP reconstruction, SSRO, and Le Fort I osteotomy are reliable and effective methods for the treatment of UTMJAJD.

Analysis of joint protein expression profile in anterior disc displacement of TMJ with or without OA.

OBJECTIVE: Anterior disc displacement (ADD) is a common clinical issue and may cause osteoarthritis (OA). However, the research of protein changes in synovial fluid as disease development marker and potential treatment clue is still insufficient. MATERIALS AND METHODS: We conducted the high-resolution mass spectrometry (MS) of synovial fluid collected from 60 patients with normal disk position to ADD and ADD with osteoarthritis (OA). The proteins with significant changes among the 3 groups were analyzed by biological information and further validated by in primary rat condyle chondrocytes and OA animal model. RESULTS: FGL2, THBS4, TNC, FN1, OMD etc. were significantly increased in ADD without OA (p < 0.05), which reflected the active extracellular matrix and collagen metabolism. FGFR1, FBLN2, GRB2 etc. were significantly increased in ADD with OA group (p < 0.05), which revealed an association with apoptosis and ferroptosis. Proteins such as P4HB, CBLN4, FHL1, VIM continuously increase in the whole disease progress (p < 0.05). Both the in vitro and in vivo results are consistent with protein changes detected in MS profile. CONCLUSION: This study firstly provides the expression changes of proteins from normal disc condyle relationship toward ADD with OA, which can be selected and studied further as disease progress marker and potential treatment targets.

Comparative study of normal condyle and temporomandibular joint prosthesis movement during mouth opening by dynamic magnetic resonance imaging and computed tomography.

Background: To analyze and compare the trajectory of condylar motion during mouth opening in normal volunteers and patients after total joint replacement (TJR) of the temporomandibular joint (TMJ). Methods: Condylar movement during mouth opening was recorded by dynamic magnetic resonance imaging (MRI) for volunteers with normal TMJs and dynamic computed tomography (CT) for patients after TMJ TJR. Trajectories of the points selected every 5 mm from the superior point of the condyle (P0) along its axis to the mandibular angle (P-25) were recorded. The arc length and curvature radius of average trajectories for each point were calculated and compared between the normal joints and TJRs, especially P-10 which is the corresponding point of the prosthesis apex without lateral pterygoid muscle (LPM) attachment at the normal joint with LPM attachment. The location of the point with the most similar trajectory was identified in the normal joints and compared with the condylar prosthesis. Results: A total of 9 volunteers with 18 normal TMJs, and 5 patients with 6 prostheses were included in this study. For normal TMJs, the average condylar trajectories during mouth opening were a concave upward curve. Meanwhile, the trajectories of contralateral normal joints in patients with unilateral TJR and all condylar prostheses were significantly decreased. The arc length and curvature radius of average trajectories gradually decreased from P0. In the normal joints, P-20 had the most similar trajectories with the average arc lengths and a curvature radius of 13.0/4.2 mm. In P-10, the average arc lengths and curvature radius of the normal cases, natural TMJ of the unilateral replacement patients, prosthetic TMJ of the unilateral replacement patients, and prosthetic TMJ of the bilateral replacement patient, were 15.6/6.6 mm, 13.1/4.9 mm, 4.7/4.4 mm, and 6.4/5.8 mm, respectively. Conclusions: P-20 in the normal joint exhibited the most similar trajectory among individuals. The trajectory difference between the prosthesis apex without LPM attachment and the corresponding point at the normal joint with LPM attachment provides a reference for fossa prosthesis functional surface design.

Intra-articular treatment of temporomandibular joint osteoarthritis by injecting actively-loaded meloxicam liposomes with dual-functions of anti-inflammation and lubrication.

Temporomandibular joint (TMJ) osteoarthritis is a common osteochondral degenerative disease which can severely affect patient's mouth opening and mastication. Meloxicam (MLX), one of the most widely used non-steroidal anti-inflammatory drugs, is the main clinical therapy for the treatment of TMJ osteoarthritis. However, the clinical effect is greatly compromised because of its poor water solubility and high lipophilicity. In the present study, we developed an actively-loaded liposomal formulation, namely MLX-Ca(AC)2Lipo, using meglumine to enhance aqueous solubility and divalent metal (Ca2+) solution to improve encapsulation efficiency. By the formation of the nano-bowl shaped MLX-Ca precipitates inside the liposomes, MLX-Ca(AC)2Lipo successfully achieved an optimal encapsulation efficiency as high as 98.4% compared with previous passive loading method (60.6%). Additionally, MLX-Ca(AC)2Lipo maintained stable, and the slow drug release not only prolonged the duration of drug efficacy but also improved bioavailability. It was shown in the in vitro and in vivo tests that MLX-Ca(AC)2Lipo downregulated the synthesis of the inflammatory factors (such as prostaglandin-E2) and as a consequence reduced chondrocytes apoptosis and extracellular matrix degeneration. Furthermore, the intra-articular injection of MLX-Ca(AC)2Lipo enhanced bioinspired lubrication of TMJ, protecting the cartilage from progressive wear. In summary, MLX-Ca(AC)2Lipo with dual-functions of anti-inflammation and lubrication is a promising nanomedicine for the treatment of TMJ osteoarthritis by intra-articular injection.

3D-Printed Porous Tantalum Scaffold Improves Muscle Attachment via Integrin-ß1-Activated AKT/MAPK Signaling Pathway.

3D-printed porous titanium (Ti) alloy scaffolds have been reported for facilitating muscle attachment in our previous study. However, the anti-avulsion ability needs to be improved. In this study, we used 3D-printed porous tantalum (Ta) scaffolds to improve muscle attachment. The differences in chemical and physical characteristics and muscle adhesion between the two scaffolds were tested and compared in the gene and protein level both in vitro and in vivo. The possible molecular mechanism was analyzed and further proved. The results showed that compared with the porous Ti alloy, porous Ta had better cell proliferation, differentiation, migration, and adhesion via the integrin-ß1 (Itgb1)-activated AKT/MAPK signaling pathway in L6 rat myoblasts. When artificially down-regulated the expression of Itgb1, cell adhesion and myogenesis differentiation were affected and the phosphorylation of the AKT/MAPK signaling pathway was suppressed. In rat intramuscular implantation, porous Ta had a significantly higher muscle ingrowth rate (85.63% ± 4.97 vs 65.98% ± 4.52, p < 0.01) and larger avulsion force (0.972 vs 0.823 N/mm2, p < 0.05) than the porous Ti alloy. These findings demonstrate that the 3D-printed porous Ta scaffold is beneficial for further clinical application of muscle attachment.

Preliminary Study of Standard Artificial Temporomandibular Joint Replacement With Preservation of Muscle Attachment.

PURPOSE: To evaluate the effect of preserving the muscle attachments when performing standard artificial temporomandibular joint replacement (TJR). PATIENTS AND METHODS: The clinical and radiological imaging data of patients who underwent standard artificial TJR with and without preservation of lateral pterygoid muscle (LPM) and masseter muscle attachments from January 2017 to December 2019 were collected. The maximum interincisal opening (MIO), lateral excursions and protrusion distances, visual analogue scale (VAS) scores of pain, diet, and quality of life (QoL) were recorded before the operation, and 1, 3, 6, and 12 months after the operation. The volumes of LPM and masseter muscles were measured and analyzed by computed tomography (CT) scans. RESULTS: Twenty-seven patients with 36 joints were included in the study. Among them, 11 joints had muscle attachment preserved, and 25 had no muscle attachment preserved. After surgery, the MIO, lateral excursions, and scores of diet, pain, and QoL in the preserved muscle attachment group were significantly better than those in the unpreserved group (P < .05). The measurement volumes of LPM and masseter muscles in the preserved group were significantly larger than that in the unpreserved group (P < .05). Changes of lateral excursion from the TJR side with and without LPM preservation were statistically correlated with the LPM volume (P < .05). CONCLUSION: Preserving muscle attachment for the standard artificial TJR is beneficial to the recovery of postoperative mandibular function.

A bilayered scaffold with segregated hydrophilicity-hydrophobicity enables reconstruction of goat hierarchical temporomandibular joint condyle cartilage.

Temporomandibular joint (TMJ) supports chewing, talking or other daily oral activities. So far, it still remains a great challenge to treat the defected TMJ condyle cartilage through tissue engineering technology. Herein, a bilayered scaffold is designed to fully reconstruct the different cartilage matrices of TMJ condyle under same induction condition. The bilayered scaffold with segregated hydrophobicity-hydrophilicity in top and bottom layer is prepared from a low and high content of polyethylene glycol (PEG) crosslinked poly (L-glutamic acid)-g-polycaprolactone (PLGA-g-PCL). The hydrophobic aggregates in top layer support the adhesion and spread of bone mesenchymal stem cells (BMSCs), thus inducing the differentation towards fibrocartilage; while aggregates (spheroids) are formed on the hydrophlic bottom layer, showing a preferable hyaline differentiation pathway under same chondrogenic induction in vitro. After 14 d in vitro induction, the scaffold/BMSCs construct is implanted in goat TMJ condyle defects. The post-operative outcome after 2 months demonstrates that the defects are fully covered by neo-cartilage. And the regenerated hierarchical TMJ condyle cartilage perfectly consist of ordered fibrocartilage and hyaline cartilage, which is same as natural condyle cartilage. These results corroborate that this bilayered scaffold with segregated hydrophilicity-hydrophobicity carrying induced BMSCs is a promising for treatment of TMJ condyle cartilage defects.

A Novel Design of Temporomandibular Joint Prosthesis for Lateral Pterygoid Muscle Attachment: A Preliminary Study.

Introduction: In temporomandibular joint (TMJ) replacement operation, due to the condylectomy, the lateral pterygoid muscle (LPM) lost attachment and had impact on the mandible kinematic function. This study aimed to design a novel TMJ replacement prosthesis for LPM attachment and to verify its feasibility by preliminary in vitro and in vivo experiments. Materials and Methods: An artificial TMJ prosthesis designed with a porous structure on the condylar neck region for LPM attachment was fabricated by a 3D printed titanium (Ti) alloy. A rat myoblast cell line (L6) was tested for adhesion and biocompatibility with porous titanium scaffolds in vitro by cell counting Kit-8 (CCK-8), scanning electron microscope (SEM), flow cytometry (FCM), real-time quantitative polymerase chain reaction (RT-qPCR), immunocytofluorescense, western blotting, etc. The porous titanium scaffolds were further embedded in the rat intervertebral muscle to analyze muscle growth and biomechanical strength in vivo. The novel artificial TMJ prosthesis was implanted to reconstruct the goat's condyle and LPM reattachment was analyzed by hard tissue section and avulsion force test. Results: L6 muscle cells showed good proliferation potential on the porous Ti scaffold under SEM scanning and FCM test. In RT-qPCR, immunocytofluorescense and western blotting tests, the L6 cell lines had good myogenic capacity when cultured on the scaffold with high expression of factors such as Myod1 and myoglobin, etc. In the in vivo experiment, muscles penetrated into the porous scaffold in both rats and goats. In rat's intervertebral muscle implantation, the avulsion force was 0.716 N/mm2 in 4 weeks after operation and was significantly increased to 0.801 N/mm2 at 8 weeks (p < 0.05). In goat condylar reconstruction with the porous scaffold prosthesis, muscles attached to the prosthesis with the avulsion force of 0.436 N/mm2 at 8 weeks, but was smaller than the biological muscle-bone attachment force. Conclusion: The novel designed TMJ prosthesis can help LPM attach to its porous titanium scaffold structure area for future function.

Preliminary clinical study of Chinese standard alloplastic temporomandibular joint prosthesis.

PURPOSE: To evaluate the preliminary clinical outcomes on the Chinese standard temporomandibular joint (TMJ) prostheses. PATIENTS AND METHODS: Patients who underwent Zimmer Biomet and Chinese standard prostheses by one surgeon between January 1st 2016 and June 30th 2017 were included in the study. Maximum incisal opening (MIO), pain, diet, and joint function were measured; CT scans were taken before and after the operation and during at least a 12-months follow-up for evaluation. RESULTS: Thirty-five patients including 12 with Chinese standard prostheses and 23 with Biomet stock prostheses participated in the study. After an average of 14.3 months follow-up, both types of prostheses could significantly improve MIO, diet, and joint function, and relieve pain (p < 0.05). There were no significant differences in diet, pain level and joint function either before or after the operation between the two types of prostheses, whereas after the operation, the MIO with Chinese standard prostheses was significantly larger than with the Biomet stock prostheses (p < 0.05). However, there was no significant difference before operation (p > 0.05). A computed tomography (CT) scan showed that no prostheses dislocated or broke, no screws loosened, and ectopic bone formation appeared around the alloplastic condyle. CONCLUSION: Chinese standard TMJ prostheses are effective and stable in clinical application. They can significantly improve mouth opening, diet, and joint function and relieve pain.

Comparison of bone adaptation after modification in biomet standard alloplastic temporomandibular joint prostheses.

PURPOSE: The aim of the study was to compare bone adaptation after design modification in Biomet stock prostheses. MATERIALS AND METHODS: Computed tomography (CT) data of the patients treated with a Biomet TMJ replacement from 2010 to 2016 were recruited. Fossa prosthesis with a bulge and 4 types of condyle-ramus angle prostheses were virtually designed and implanted by computer-assisted simulation. The amount of bone trimming including fossa, mandibular ramus and bone graft were measured by ProPlan CMF 1.4 software. The differences between the original and modified prostheses were compared by SPSS 17.0 software for statistical analysis. RESULTS: There were 54 patients' CT data included in the study. The amount of fossa bone trimming was 150.20 mm3 in the modified prosthesis and 281.82 mm3 in the original one. The amount of ramus bone trimming was 103.86 mm3 in the modified prosthesis and 229.45 mm3 in the original one. The amount of fossa bone grafting was 95.88 mm3 in the modified prosthesis and 263.03 mm3 in the original one. There were significant differences between them (p = 0.000). CONCLUSIONS: The modified Biomet prostheses design requires less bone trimming and grafting for implantation.

Clinical and Radiologic Follow-Up of Zimmer Biomet Stock Total Temporomandibular Joint Replacement After Surgical Modifications.

PURPOSE: The aim of this study was to evaluate the clinical and radiologic results of Zimmer Biomet stock prostheses (Jacksonville, FL) in temporomandibular joint replacement after surgical modifications during at least 1 year of follow-up. PATIENTS AND METHODS: We recruited patients treated by Zimmer Biomet stock prostheses after technical modifications, including digital templates, autogenous ipsilateral bone grafting from the mandible to the fossa, salvaging of the disc remnant and suturing it to the medial aspect of the prosthesis, and fat grafts from a retromandibular incision, between 2010 and 2016. Clinical examination findings including maximal incisal opening; visual analog scale scores for pain, diet, and mandibular movement; and quality of life were compared before the operation and at least 1 year postoperatively. The status of the fossa bone graft was evaluated by computed tomography examination. RESULTS: The study comprised 38 joints in 33 patients with diagnoses including osteoarthritis, ankylosis, and neoplasm. Compared with before the operation, maximal incisal opening and visual analog scale scores for diet, function, and pain level, as well as the quality-of-life survey score, were considerably improved during the last follow-up. Computed tomography scans showed all bone grafts were completely healed within the fossa 1 year after surgery. There was no ectopic bone formation, screw loosening, or component displacement or breakage. CONCLUSIONS: Our surgical modifications of Zimmer Biomet stock prostheses showed good results for at least 1 year of follow-up.

A Comparison of Clinical Follow-Up of Different Total Temporomandibular Joint Replacement Prostheses: A Systematic Review and Meta-Analysis.

PURPOSE: There are different total temporomandibular joint (TMJ) prostheses on the market but no comparison of their efficacy. The purpose of this meta-analysis was to evaluate the effectiveness of different TMJ replacement (TJR) systems. MATERIALS AND METHODS: A systematic review and meta-analysis was performed using the PubMed, Embase, Medline, and Cochrane Library search engines in May 2017 to identify qualified studies. Outcome measurements were changes in maximal incisal opening (MIO), pain, dietary limitations, and functional deficiencies from before to after TJR. Analyses of heterogeneity, sensitivity, and publication bias were performed. A fixed-effects model was used for the meta-analysis of pooled weighted mean differences in pre- versus postoperative MIO, pain, diet, and function. RESULTS: Twenty studies with 1,262 patients were included in the meta-analysis. Comparison of the TJR systems showed no real difference for pre- versus postoperative MIO, pain, diet, and function. MIO and functional efficiency decreased gradually over time, but effective pain relief and improvements in dietary limitations were stable with no relevant differences during follow-up. Comparison of the custom and stock devices showed similar results for pre- and postoperative MIO, pain, function, and diet. CONCLUSION: This analysis showed no relevant difference in treatment outcomes among the TJR systems.