Techniques of Yang’s arthroscopic discopexy for temporomandibular joint rotational anterior disc displacement

Morphological factors influencing the progression of temporomandibular joint anterior disc displacement with reduction to without reduction after contralateral joint arthroscopic discopexy: a retrospective study

The aim of this retrospective cohort study was to identify morphological risk factors associated with the progression of temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDwR) to without reduction (ADDwoR) in the contralateral joint following arthroscopic discopexy. Among 80 patients, 26 divided into a 'progression' group versus 54 without progression based on the disc position in the contralateral joint at postoperative follow-up. Patient characteristics and the disc length, disc folding angle, anterior distance of the disc relative to the condyle, and angle between the disc and condyle were analysed. Univariate analysis revealed that longer anterior distance and greater angle between the disc and condyle increased ADDwoR risk(both P < 0.001), while a longer disc length (P < 0.001) and a greater disc folding angle (P = 0.034) reduced progression likelihood. Multivariable logistic regression and receiver operating characteristic curves confirmed disc length and anterior distance to be significantly associated with progression to ADDwoR. In conclusion, following unilateral arthroscopic discopexy, patients with contralateral ADDwR are at risk of progression to ADDwoR, with disc length and anterior distance relative to the condyle being key morphological risk factors.

"Modified arthroscopic disc repositioning and suturing technique for the treatment of TMJ anterior disc displacement without reduction: A technical note"

Anterior disc displacement without reduction (ADDwoR) is one of the most common types temporomandibular disorders (TMD), which is often characterized by joint pain, abnormal joint sounds, and limited mouth opening. Disc repositioning has been described as an effective method to reduce joint pain and improve range of motion. Yang's arthroscopic disc repositioning and suturing surgery has been reported to be the most stable technique with 95%-98% of success rate. However, the main challenges of this procedure are as follows: (1) it is relatively complex and requires a pair of customized grippers (lasso-type and hook-type); (2) it needs a self-designed surgical suture, which is hardened at the end of the suture. The aim of the study was to introduce the modification to the technique and report on the efficacy of the treatment. A total of 25 patients (36 joints) with anterior disc displacement without reduction were included. The visual analogue scale (VAS) scores (0-10) decreased to 0.48 ± 0.92 at 3 months postoperatively (P < 0.0001). Patients with limited mouth opening preoperatively detected a significant improvement in maximum inter-incisal opening (MIO) of 37.59 ± 4.33 mm (P < 0.0001). MRI showed the discs were repositioned in all 25 patients, giving a success rate of 100%. This study reports a modification to Yang's technique which enables extracorporeal suture threading, without excessive limitations on the suture materials, and allowing for the completion of all suturing procedures using one single instrument. Limitations should be noted such as the small sample size and short follow-up period, and further investigation will be carried out in the future.

The role of the holmium laser in increasing the success rate of temporomandibular joint arthroscopic discopexy

The purpose of this study was to compare the effects of anterior releasing of the temporomandibular joint disc during arthroscopic discopexy surgery with a holmium laser versus manual instrumentation. A total of 80 patients (139 joints), divided into two groups. Anterior releasing surgery was performed using manual surgical instruments in 40 patients (70 joints) and with holmium laser assistance in the other 40 patients (69 joints). Statistical analyses, including χ2 tests and multivariate analysis, assessed factors impacting surgical success. The results showed that discopexy success was significantly higher with holmium laser use compared to manual instruments (odds ratio 4.41, P = 0.003). In addition, a preoperative diagnosis of anterior disc displacement with reduction (ADDwR) was found to be significantly more likely to result in surgical success compared to anterior disc displacement without reduction (ADDwoR) or idiopathic condylar resorption (odds ratio 5.91, P = 0.001). This study found that the use of holmium laser assistance, as compared to manual surgical instruments, significantly enhanced the success rate of arthroscopic discopexy in the temporomandibular joint. Furthermore, patients classified as ADDwR exhibited a notably higher surgical success rate compared to those classified as ADDwoR or idiopathic condylar resorption.

Early management of anterior disc displacement without reduction: Evaluating the effectiveness of modified arthroscopy discopexy with anterior disc repositioning splint

BACKGROUND

This study aims to assess the therapeutic efficacy of a modified arthroscopy discopexy suturing technique in combination with an anterior disc repositioning splint (ARS) for the treatment of early phase anterior disc displacement without reduction (ADDwoR) patients.

METHODS

During 2021-2022, early phase ADDwoR cases were included and underwent modified arthroscopy discopexy suturing surgery and ARS therapy after surgery. Pre- and post-surgical evaluation parameters include the visual analogue scale (VAS) for pain, maximum mouth opening (MMO), and disc-condyle relationship on MRI. Patients were followed up for a period of 6 months after surgery. Statistical significance was considered when p < 0.05.

RESULTS

A total of 31 unilateral early phase ADDwoR cases were included, with an average age of 26.97. The VAS scores of pain decreased from 4.87 to 1.61, while MMO increased from 23.13 mm to 39.35 mm(p < 0.05). MRI evaluations at 1 month and 6 months post-surgical revealed a disc reduction rate of 93.55% and 90.32%, respectively.

CONCLUSION

The modified arthroscopy discopexy suturing technique combined with ARS therapy after surgery proves to be an effective, minimally invasive and simplified approach for the treatment of early phase ADDwoR patients.

"The effect of disc repositioning on regenerative condylar bone remodelling in juvenile patients with temporomandibular joint osteoarthritis: a retrospective cohort study"

OBJECTIVES

A retrospective cohort study was conducted to compare the treatment outcomes between arthroscopic disc repositioning and suturing surgery, and conservative treatment (without disc repositioning) in juvenile patients with anterior disc displacement without reduction (ADDwoR) and temporomandibular joint osteoarthritis (TMJOA).

METHODS

Patients treated with arthroscopic surgery (surgery group) between March 2022 and March 2023, and those treated with conservative therapy (control group) between July 2014 and August 2022 were included. The patients were assessed clinically and with CBCT before and after the treatments (minimum interval of 6 months).

RESULTS

A total of 38 patients were included in the study, with 19 patients in each of the groups. The postoperative mouth opening and joint pain improved significantly in both groups (P < 0.05), and there was no significant difference between them (P > 0.05). Besides clinical symptom relief, both treatments could promote regenerative condylar remodeling. More importantly, the increase in condylar head height and volume in the surgery group was significantly larger than those in the control group (P < 0.001). The occurrence of regenerative condylar remodeling in the surgery group (96.6%) was significantly higher than that in the control group (68.4%, P < 0.001). However, the occurrence of condylar regeneration was exclusively observed in the surgery group.

CONCLUSIONS

The arthroscopic surgery has comparable effect to the conservative treatment on improving clinical symptoms, while it has better regenerative condylar remodeling results compared to the conservative treatment.

CLINICAL RELEVANVE

This study demonstrated that arthroscopic surgery was superior to conservative treatment in promoting regenerative condylar remodeling, which is of significance to guide the treatment decision of juvenile patients with ADDwoR and TMJOA.

Arthroscopic treatment of temporomandibular dysfunction: preliminary results from a prospective follow up of over five years

Patients with refractory temporomandibular dysfunction (TMD) despite conservative therapies often require surgical intervention. Although techniques such as arthrocentesis or arthroscopy have been established for years, there remains a dearth of evidence regarding the long-term efficacy of these interventions. This preliminary prospective study aims to elucidate the outcomes of arthroscopic treatment conducted over five years ago in patients with temporomandibular dysfunction. A study involving 31 patients with temporomandibular dysfunction who underwent level II arthroscopic surgery prior to 2019 is presented. The principal objective parameter for joint function was mouth opening, while the primary subjective parameters included pain, which was measured using the visual analogue scale (VAS), and quality of life, assessed using the OHIP-14sp questionnaire. Objective parameters were assessed preoperatively at one year and five years postoperatively, while quality of life was evaluated both preoperatively and five years after the procedure. Subsequently, the long-term status of patients was analysed, including surgical outcomes and the necessity for supplementary techniques such as second arthroscopy or open surgery. The quality-of-life scores significantly improved (p < 0.001) after five years of follow up when compared with preoperative assessments. Pain levels exhibited a statistically significant decrease over the follow-up period (p < 0.001). Significant differences were observed between preoperative and both 12-months' and five-years' follow up (both p < 0.001) but not between the 12-month and five-year marks (p = 0.899). Similar trends were noted for maximum mouth opening, with differences between pre-surgery and both 12-months' and five-years' follow up (p = 0.049 and p = 0.005, respectively) but not between the 12-month and five-year assessments (p = 0.482). Mouth opening at 12 months (p = 0.003) and five years (p = 0.032), as well as OHIP results at five years (p = 0.003), demonstrated statistically significant differences between groups according to the final status. In all cases, poorer clinical outcomes post-surgery (requiring a second arthroscopy or meniscectomy) correlated with decreased mouth opening and worse OHIP results. Arthroscopy emerges as an effective technique in the long-term treatment of temporomandibular joint dysfunction, as parameters such as pain and maximum mouth opening improve, and this improvement remains stable at the five-year follow up.

Evaluation of mandibular motions in patients with anterior disc displacement during mouth opening and closing using finite helical axis

Understanding temporomandibular joint (TMJ) kinematics is essential for the clinical diagnosis and treatment of TMJ disorders. Yet, a comprehensive description of mandibular motion information in patients with anterior disc displacement (ADD) is lacking. The finite helical axis (FHA) is a mathematical model describing the motion of a rigid body in space. This model quantifies mandibular motion patterns by differentiating between rotation around the FHA and translation along it. This study aimed to compare the mandibular motion patterns between patients with ADD and asymptomatic subjects during mouth opening and closing utilizing the FHA. Ten asymptomatic subjects (2 females and 8 males, aged 19-22) and ten patients with ADD (8 females and 2 males, aged 19-57) were tracked using an optical motion tracking system for mouth opening and closing. The FHA during mouth opening and closing was determined from motion trajectory. The distance from the condylar center to the FHA (dCP), the angles between the FHA and the head coordinate system (θx, θy, θz), and the global fluctuation of the FHA spatial orientation (θf) were further calculated. In addition, the helical axis of each frame relative to the initial frame was computed to determine the maximum rotation angle (Θmax) and maximum offset (Tmax) of mandibular motion during mouth opening and closing. It was found that Θmax, Tmax, dLCPmean, dLCPmin, θx, and θf for patients with ADD differed significantly from those of asymptomatic subjects. These findings imply that the FHA effectively describes the disparities between patients with ADD and asymptomatic subjects.

Unlocking the Temporomandibular Joint: CT, MRI, and Arthroscopic Correlation

The temporomandibular joint constitutes a synovial connection between the mandible and the skull base and plays a pivotal role in functions such as jaw movement, chewing, and verbal and emotional expression. Temporomandibular joint dysfunction is observed in about 30% of the population, with a higher prevalence in young to middle-aged women. Interestingly, a majority of individuals affected do not report pain, and only 5%-10% of symptomatic cases necessitate therapeutic intervention. The most common temporomandibular joint disorder manifests as pain in the masticatory muscles and is referred to as myofascial syndrome. However, articular disorders are also very common, usually due to disk displacement and degenerative or inflammatory arthropathies. Less frequently, the temporomandibular joint may be affected by a range of congenital and acquired conditions such as trauma and neoplasms. Imaging becomes necessary for the small percentage of patients who do not respond to conservative management or when there is uncertainty in the diagnosis. A comprehensive understanding of the normal imaging appearance of the temporomandibular joint as well as the wide range of potential pathologic conditions is essential for conducting an accurate radiologic assessment. Moreover, collaboration among multidisciplinary teams and the correlation of imaging findings with arthroscopic observations are crucial to advancing the diagnosis and treatment of temporomandibular joint dysfunction. ©RSNA, 2024 Supplemental material is available for this article.

A guide for temporomandibular joint surgery using a simple surgical classification - A narrative-style review

The aim of this narrative style review is to clarify the role of TMJ surgery in the management of specific TMJ disorders by introducing a simple and practical surgical classification. A decade ago, a new surgical classification was published which, like the Wilkes classification, included the five escalating degrees of joint pathology, but with more practical definitions and proposed surgical options for each of the disease categories. The classification begins with Category 1 - painful but otherwise structurally normal joints, which are largely managed nonsurgically. Categories 2 and 3 denote reducing and nonreducing disc displacement of the TMJ, respectively, with the former treated by TMJ arthrocentesis or level 1 arthroscopy and the latter best managed with disc repositioning or discopexy. Category 4 describes degenerative changes to the disc itself, where the disc cannot be salvaged and is thus removed with TMJ discectomy. Lastly, Category 5 refers to end-stage joint disease, where none of the joint components can be salvaged; both the disc and condylar head are sacrificed, and the TMJ is reconstructed with a prosthetic total joint replacement. In the decade since its publication, various studies have served to validate the usefulness of the TMJ surgical classification, and how it can be applied to better understand the role of TMJ surgery in everyday clinical practice.

Evaluation of clinical impact of two types of Temporomandibular joint disc reduction and fixation

OBJECTIVE

To evaluate the clinical effectiveness and stability of open suture versus micro-screw anchored disc reduction and fixation in treating disc displacement without reduction in the anterior temporomandibular joint.

METHODS

A total of 38 patients (51 sides) with anterior disc displacement without reduction (ADDwR) of the TMJ treated in our hospital from August 2021 to January 2023 were selected, including 19 cases in group A (23 sides) treated with open temporomandibular joint disc reduction and anchorage, and 19 cases in group B (28 sides) treated with temporomandibular joint disc reduction and suture. The Magnetic Resonance Imaging (MRI) data of the two groups before and after operation were compared to evaluate the effective rate of articular disc reduction, the change of articular disc length, The Maximal Interincisal Opening (MIO) and Numeric Rating Scale (NRS) were measured before and after operation.

RESULTS

In group A, the MRI effective rate 6 months after disc reduction was 95.65 % (22/23), the disc length gain was 1.74 mm, MIO was 40.32±5.067 mm, and NRS was 0.47±0.697. The MRI effective rate 6 months after disc reduction in group B was 100 % (28/28). The disc length gain was 1.78 mm, MIO was 41.58±3.746 mm, and NRS was 0.00. There was no significant difference between the two groups (P > 0.05).

CONCLUSIONS

TMJ disc reduction and suture and open TMJ disc anchorage can effectively reduce the TMJ disc. The TMJ disc stability is high at 6 months after operation, and the pain and mouth opening can be improved, which is worthy of further promotion in clinical practice.

Comparison of the TMJ arthroscopy discopexy techniques: A systematic review and meta-analysis

This article aims to analyze which of the main arthroscopic discopexy techniques has the best results and if there are differences between the techniques for both pain and maxillary intercuspid opening. A systematic review and meta-analysis was performed according to the PRISMA statement. An electronic search was performed with no publication date restriction in PubMed, Ovid and Embase. The PICO criteria: (P) Patients: With temporomandibular internal disorders with discopexy indication. (I) Intervention: Temporomandibular joint arthroscopic discopexy. (C) Comparison: Arthroscopic discopexy among different techniques classified as non-rigid, semi-rigid and rigid. (O) Outcomes: Impact in clinical conditions such as pain and maximum mouth opening. The inclusion criteria were Patients with temporomandibular internal disorders with discopexy indication performed with different techniques classified as non-rigid, semi-rigid and rigid. The outcomes evaluated were pain and maximum mouth opening. Case series, cohort studies, quasi-experimental studies, and randomized clinical trials with at least 3 months of follow-up were included. The exclusion criteria considered were patients with related concomitant surgeries, patients with associated neoplastic disease or connective tissue disease. A total of 1515 joints where 1400 discopexies were performed including 849 females and 204 males. The most common diagnostic was Wilkes stage III in 257 joints. For pain and oral opening, the semi-rigid technique shows the best results median (MD) 4.84 (CI 2.52-7.16; p = 0.001, I2:100%), MD -2.78 (CI -4.34, -1.21; p = 0.001, I2:99%), respectively. The rigid technique has the greatest probability for complications MD 0.14 CI 95% (0.00, -0.28). Although the semi-rigid technique showed better results, there is no statistically significant difference. However, due to the heterogeneity of the studies, the results should be interpreted with caution.

The hue of temporomandibular joint arthroscopy under local versus general anaesthesia

BACKGROUND

Temporomandibular joint arthroscopy (TMJA) is often performed under general anaesthesia (GA) worldwide on an inpatient basis, whereas local anaesthesia (LA) is not equally considered as the standard procedure.

OBJECTIVES

To compare the efficacy between LA and GA when performing TMJA.

METHODS

This study retrospectively reviewed a total of 182 patients in LA group and 91 patients in GA group who underwent TMJA for the management of disc displacement. Patients were divided into two groups based on type of anaesthesia used for surgery; LA group and GA group. Comparisons were made based on operative time, intubation and extubation time (for GA only), hospital stay duration, total cost and post-operative clinical and radiological outcomes.

RESULTS

The demographics and pre-operative clinical assessments were matched in both groups. No post-operative significant difference was found in outcomes when performing TMJA under LA compared to GA in terms of pain reduction (p = .016) and improvement in mouth opening (p = .866). The median operative time and hospital stay duration for LA group were significantly less compared to GA group (p < .001). GA group required an additional intubation and extubation time, whereas LA group patients were waived from it. TMJA for LA group was performed in the minor procedure setup, which reduced the costs for surgery (p < .001). Post-operative disc position was excellent and good with an overall success rate of 95%.

CONCLUSION

The use of LA performing TMJA reduces operating time, costs, hospital stay and recovery room time than GA group. Furthermore, TMJA performed under LA shared similar post-operative clinical and radiological outcomes with those performed under GA.

Feasibility of simultaneous TMJ arthroscopy in ADDwoR patients undergoing orthognathic surgery for jaw deformity

This study evaluated the feasibility of simultaneous temporomandibular joint (TMJ) arthroscopy and orthognathic surgery as a new treatment strategy for anterior disc displacement without reduction (ADDwoR) patients with severe jaw deformities. Twelve ADDwoR patients with facial deformities who underwent arthroscopy and orthognathic surgery between September 2015 and December 2019 were retrospectively evaluated. Pre- and postoperative maximum incisal opening (MIO) and joint pain were recorded. Computed tomography (CT) and three-dimensional cephalometric analysis were performed at 3 (T1) and ≥6 (T2) months postoperatively. Magnetic resonance imaging (MRI) of the TMJ was performed before, ≤7 days after and ≥6 months after surgery. The lateral profile radiological findings, the symmetry of the maxilla and mandible, and the MRI measurements were compared. Anterior disc displacement did not recur, and the maximum incisal opening (MIO) increased from 27.4 mm to 32.7 mm after surgery (p < 0.05). No significant differences were found in the lateral profile, symmetry indices or condylar height via MRI between T1 and T2. Joint morphology and the position of both the maxilla and mandible remained stable during postoperative follow-up, while joint symptoms were markedly relieved and facial appearance was noticeably improved. Combined arthroscopy and orthognathic surgery is effective and recommended for ADDwoR patients with jaw deformities.

Arthroscopic reduction and rigid fixation of the anteriorly displaced temporomandibular joint disc without reduction using titanium screw: a case series

OBJECTIVES

To evaluate the effectiveness of arthroscopic reduction and rigid fixation (ARRF) using a suture-free titanium screw as a treatment approach to temporomandibular joint's (TMJ) anterior disc displacement without reduction (ADDwoR) and assess its impact on clinical outcomes, including improvements in symptoms related to TMJ disorders.

MATERIALS AND METHODS

A series of twenty patients presented to the Department of Orthognathic and Temporomandibular Surgery at West China Hospital of Stomatology between September 2022 and January 2023, complaining of symptoms such as pain, clicking, and limited mouth opening. Standard magnetic resonance image (MRI) imaging T1 and T2 sequences in both sagittal and coronal views study with closed and maximal open mouth positions were taken preoperatively to assess the disc's position, integrity, and shape. Also, cone-beam computed tomography (CBCT) scans images to find any degenerative changes and evaluate the condylar bone's features and volume. Additionally, the clinical examination assesses limited oral opening, mechanical pain, and the presence of any noises such as clicking and crepitus. All cases were treated under general anesthesia using the arthroscopic release, reduction, and rigid fixation of the TMJ's ADDwoR to establish a normal disc-condyle relationship and to restore the functional position.

RESULTS

Patients' symptoms, such as pain and mouth opening, improved significantly following the arthroscopic treatment. Postoperative MRI and CBCT imaging follow-up conducted at 6 months demonstrated the stable position of the reduced TMJ disc and the fixation screw. Notably, none of the patients exhibited signs of relapse during this follow-up period.

CONCLUSION

Overall, the ARRF of TMJ's ADDwoR using a suture-free titanium screw proved to be safe and provides satisfactory results, in addition to the several advantages of using suture-free titanium screws, such as biocompatibility, strong fixation, and durability. However, it is a technically demanding procedure requiring extensive, long-term training.

CLINICAL RELEVANCE

ARRF using a cost-effective fixation titanium screw to treat ADDwoR emerges as a clinically effective minimally invasive approach.

Effect of arthroscopic discopexy on condylar growth in adolescents with temporomandibular joint disc displacement without reduction: A retrospective self-controlled case series study

This study was a retrospective self-controlled study that aimed to evaluate the effect of arthroscopic discopexy on condylar height and mandibular position in adolescents with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR). Patients between 10 and 20 years of age and diagnosed with bilateral TMJ ADDwoR by magnetic resonance image (MRI) were included in this study. All patients underwent a period of natural course before arthroscopic surgery and then a follow-up period postoperatively. Changes in condylar height and mandibular position were measured by MRI and X-ray radiographs. Data were analyzed by paired t-test, Pearson correlation analysis, and generalized estimating equations. This study comprised a total of 40 patients with a mean age of 14.80 years. Pearson correlation analysis showed correlations between condylar height and mandibular position changes. The condylar height change during the post-operative period was significantly higher than that during natural course period (3.57 mm, p < 0.001). The changes in mandibular position (including ANB angle, SNB angle, and Pog-Np) were significant different (all p < 0.05) between the two periods. This study found that arthroscopic discopexy can promote condylar growth and correct dentofacial deformity in adolescents with bilateral TMJ ADDwoR.

Effect of TMJ disc position on condylar bone remodeling after arthroscopic disc repositioning surgery

PURPOSE

The objective of this study was to analyze the effect of TMJ disc position on condylar bone remodeling after arthroscopic disc repositioning surgery.

METHODS

Nine patients with anterior disc displacement without reduction (ADDWoR, 15 sides) who underwent arthroscopic disc repositioning surgery were included. Three-dimensional (3D) reconstruction of the articular disc and the condyle in the closed-mouth position was performed using cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI) data. Then, the CBCT and MRI images were fused and displayed together by multimodal image registration techniques. Morphological changes in the articular disc and condyle, as well as changes in their spatial relationship, were studied by comparing preoperative and 3-month postoperative CBCT-MRI fused images.

RESULTS

The volume and superficial area of the articular disc, as well as the area of the articular disc surface in the subarticular cavity, were significantly increased compared to that before the surgical treatment（P < 0.01）. There was also a significant increase in the volume of the condyle (P < 0.001). All condyles showed bone remodeling after surgery that could be categorized as one of two types depending on the position of the articular disc, suggesting that the location of the articular disc was related to the new bone formation.

CONCLUSIONS

The morphology of the articular disc and condyle were significantly changed after arthroscopic disc repositioning surgery. The 3D changes in the position of the articular disc after surgery tended to have an effect on condylar bone remodeling and the location of new bone formation.

Influence of local factors on the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint anterior disc displacement without reduction: a retrospective longitudinal study

The aim of this retrospective longitudinal study was to investigate the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR), and to determine whether local or systemic factors influence this growth. A total of 145 patients aged 10-20 years who were diagnosed with ADDwoR by magnetic resonance imaging were included. Patients who underwent arthroscopic discopexy were assigned to the arthroscopy group (n = 108) and others to the control group (n = 37). Demographic information, clinical assessments, body indicators, and bone density information were collected. Condylar height, disc length, and disc position were measured. The mean condylar height change in the arthroscopy group was 2.12 mm more than that in the control group (P < 0.001). Condylar growth after surgery was negatively correlated with age (P = 0.017) and disc length (P = 0.015), and positively correlated with follow-up duration (P = 0.002) and disc position (P < 0.001). Moreover, arthroscopic discopexy patients had better outcomes regarding improvements in pain (P = 0.024), maximum inter-incisal opening (P < 0.001), and quality of life (P < 0.001) than control patients. In conclusion, arthroscopic discopexy can restore condylar growth and relieve symptoms in ADDwoR patients, and the condylar growth is closely related to the local factors.

Temporomandibular joint disc repositioning and occlusal splint for adolescents with skeletal class II malocclusion: a single-center, randomized, open-label trial

BACKGROUND

Temporomandibular joint (TMJ) disc repositioning through open suturing (OSu) is a new disc repositioning method. Its result for adolescents with condylar resorption and dentofacial deformities combined with and without postoperative occlusal splints (POS) has not been well studied.

OBJECTIVE

This study was to evaluate and compare the effects of OSu with and without POS in the treatment of TMJ anterior disc displacement without reduction (ADDwoR) in adolescent skeletal Class II malocclusion.

METHODS

A total of 60 adolescents with bilateral ADDwoR were enrolled in this study. They were randomly allocated into two groups: OSu with and without POS. Magnetic resonance imaging (MRI) and lateral cephalometric radiographs were used to measure changes in condylar height and the degree of skeletal Class II malocclusion from before operation and at 12 months postoperatively. Changes in these indicators were compared within and between the two groups.

RESULTS

After OSu, both groups exhibited significant improvements in condylar height and occlusion at the end of 12 months follow-up (P < 0.05). The group of OSu with POS had significantly more new bone formation (2.83 ± 0.75 mm vs. 1.42 ± 0.81 mm, P < 0.001) and improvement in dentofacial deformity than the group of OSu only (P < 0.05). The new bone height was significantly correlated with POS (P < 0.001), the changes of SNB (P = 0.018), overjet (P = 0.012), and Wits appraisal (P < 0.001).

CONCLUSION

These findings indicated that OSu can effectively stimulate condylar regeneration and improve skeletal Class II malocclusion in adolescents with bilateral ADDwoR. The results are better when combined with POS.

TRIAL REGISTRATION

This trial was prospectively registered on the chictr.org.cn registry with ID: ChiCTR1900021821 on 11/03/2019.

A Bibliometric Analysis of Research on Temporomandibular Joint Disc Displacement from 1992 to 2022

The temporomandibular joint (TMJ) disc displacement is the most common temporomandibular disorders (TMD) condition. It causes clicking, pain, limited mandibular movements, and even masticatory difficulties in many people. The aim of this study is showcasing hotspots and frontiers in the field and providing a reference for the future research by a bibliometric analysis. Studies published from 1992 to 2022 were retrieved from Web of Science Core Collection on 23 April 2023. A total of 1882 studies (1739 articles and 143 reviews) were included in the bibliometric analysis. From 1992 to 2022, the annual number of publications and citations greatly increased. The United States of America (USA) contributed the most publications about TMJ disc displacement. Shanghai Jiao Tong University was the most productive institution; meanwhile, Yang, C. from this institution was the most prolific author. The University of Washington was the most influential institution, and Brooks, S. was the most influential author. Diagnostic criteria and management of TMJ disc displacement, as well as TMJ disc displacement-associated conditions, might be a hotspot for current global research. We provided an objective and valuable reference for future research on TMJ disc displacement.

Comparison between disc repositioning by open surgery versus occlusal splint in the treatment of temporomandibular joint anterior disc displacement without reduction: A retrospective cohort trial of short-term results

To compare the short-term clinical results between disc repositioning by open surgery (DROS) and stabilization splint (SS) for the treatment of temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR). Patients diagnosed with ADDwoR by magnetic resonance imaging (MRI) and treated by either DROS or SS from June 2020 to January 2022 were reviewed. They were selected to match the baseline data before each treatment and then to compare the clinical results including maximum interincisal opening (MIO), protrusion and lateral excursion distances, visual analogue scale (VAS) scores of pain, diet, and quality of life (QoL) and their effective rates, total satisfaction rate after 3 and 6 months of the treatment, and between the 2 treatment methods. SPSS software was used to analyze the statistical differences. A total of 175 patients were included in the study. There were 95 patients in the DROS group and 80 patients in the SS group. MIO and VAS scores were significantly improved after each treatment at 3 and 6 months (p < 0.05). DROS improved more at 6 months than 3 months (p < 0.001), whereas SS had no significant changes (p > 0.05). DROS had significantly better MIO, VAS score and effect rates than SS (p < 0.001). The total satisfaction rate was 94.73% in DROS and 86.25% in SS. The protrusion and lateral excursions decreased after DROS at 3 months (p < 0.001) but improved at 6 months to better than before the surgery (p = 0.03, p = 0.10). There were no significant changes in protrusion and lateral excursions after SS (p > 0.05, p > 0.05). DROS had better short-term clinical results than SS in the treatment of ADDwoR.

Arthroscopic Disk Repositioning After Failed Open Disk Repositioning

PURPOSE

Open disk repositioning has been long achieving excellent functional and stability outcomes. However, still remains some relapses for whom a second open surgery is often challenging. This study aimed to evaluate the effectiveness of arthroscopic disk reposition as an alternative surgery for unsuccessful cases of anterior disk displacement (ADD) after an initial open disk repositioning.

MATERIALS AND METHODS

This retrospective study included all patients who underwent secondary arthroscopy for disk repositioning of the relapsed ADD after an initial open surgery between January 2012 to June 2017. The redo arthroscopic disk repositioning and suturing procedure was the primary predictor input variable in this study. Outcome evaluation was based on both clinical (visual analog scale and maximal interincisal opening) and magnetic resonance imaging data.

RESULTS

Twenty-seven joints fulfilling the inclusion criteria were included. A significant improvement was detected at 24-month postoperatively compared with the baseline visual analog scale. The maximal interincisal opening showed a statistical improvement from 25.07 mm preoperatively to 38.44 mm at 24-month postoperatively. Twenty-six joints maintained a stable disk position with only 1 joint relapsed to ADD without reduction.

CONCLUSION

Arthroscopic disk reposition and suturing technique is a reliable and effective repeat surgery after failed initial open disk repositioning for management of ADD.

Proteome Analysis of Temporomandibular Joint with Disc Displacement

Disc displacement without reduction is a common disorder of the temporomandibular joint, causing clinical symptoms and sometimes condylar degeneration. In some cases, bone regeneration is detected following disc-repositioning procedures. Until now, however, systems-wide knowledge of the protein levels for condylar outcome with disc position is still lacking. Here, we performed comprehensive expression profiling of synovial fluid from 109 patients with disc displacement without reduction using high-resolution data-independent acquisition mass spectrometry and characterized differences in 1,714 proteins. Based on magnetic resonance imaging, samples were divided into groups with versus without condylar absorption and subgroups with versus without new bone. For the proteomic analysis, 32 proteins in groups presented with statistical significance (>2-fold, P < 0.05). Pathways such as response to inorganic substances, blood coagulation, and estrogen signaling were significantly expressed in the group with bone absorption as compared with pathways such as regulation of body fluid levels, vesicle-mediated transport, and focal adhesion, which were enriched in the group without bone absorption. In subgroup analysis, 45 proteins of significant importance (>2-fold, P < 0.05) were associated with pathways including would healing, glycolysis and gluconeogenesis, and amino acid metabolism. Combined with clinical examination, molecules such as acetyl-CoA carboxylase beta (ACACB) and transforming growth factor beta 1 (TGFB1) were related to features such as visual analog scale and maximum interincisal opening (P < 0.05). In addition, 7 proteins were examined by Western blotting, including progesterone immunomodulatory binding factor 1 (PIBF1), histidine-rich glycoprotein (HRG), and protein kinase C and casein kinase substrate in neurons 2 (PACSIN2). In conclusion, this study provides the first proteome analysis of condylar absorption at disc displacement without reduction and postoperative new bone formation after disc reposition. Integrated with clinical data, this analysis provides an important insight into the proteomics of condylar modification at disc position.

Review of the studies on the relationship and treatment of anterior disc displacement and dentofacial deformity in adolescents

Anterior disk displacement (ADD) is a common type of temporomandibular joint (TMJ) internal derangement. In adolescents, the relationship between ADD and dentofacial deformities are brought into focus. Whether treatment is needed, or what kind of treatment are effective are still without a consensus. From the literature review, the consequences of ADD without treatment and the effect on disk repositioning were summarized. The results showed that after ADD, condylar height was prone to reduce that may lead to or aggravate dentofacial deformities in adolescents. Disk repositioning could promote the regeneration of condylar bone, thus improving the development of dentofacial deformities.

Arthroscopic discopexy versus natural course of temporomandibular joint anterior disc displacement: a longitudinal study of clinical and radiological outcomes

The aim of this study was to assess the various outcomes of arthroscopic discopexy compared to the natural course of anterior disc displacement (ADD) longitudinally in the same patients. A retrospective review was performed of 108 patients (152 joints) who experienced the natural course of ADD for a period of time and then underwent arthroscopic discopexy. The outcome was evaluated clinically and by magnetic resonance imaging. The natural course of ADD showed significant deterioration in pain, diet, and quality of life, and also a significant reduction in inter-incisal opening (all P < 0.001), while significant improvements in all clinical parameters were observed at the final postoperative follow-up (all P < 0.001, compared to the last preoperative visit). During the natural course, there was a significant shortening of condylar height, mandibular height, and disc length, and an increase in disc displacement distance (all P < 0.001). Postoperative follow-up revealed the restoration of condylar height and mandibular height, and all discs were significantly repositioned with an increased disc length (unfolded) (all P < 0.001). Bearing in mind the assumption of a low evidence base due to bias resulting from the retrospective non-double-blinded study design and the variable duration of the natural disease course prior to surgery, this study found that the natural course of ADD led to degenerative changes in the joint structures and clinical symptoms, whereas arthroscopic discopexy led to a restoration of the bony structures and the alleviation of clinical symptoms.

Disc repositioning by open suturing vs. mini-screw anchor: stability analysis when combined with orthognathic surgery for hypoplastic condyles

Background

Disc repositioning by Mitek anchors for anterior disc displacement (ADD) combined with orthognathic surgery gained more stable results than when disc repositioning was not performed. But for hypoplastic condyles, the implantation of Mitek anchors may cause condylar resorption. A new disc repositioning technique that sutures the disc to the posterior articular capsule through open incision avoids the implantation of the metal equipment, but the stability when combined with orthognathic surgery is unknown. The purpose of this study was to evaluate the stability of temporomandibular joint (TMJ) disc repositioning by open suturing in patients with hypoplastic condyles when combined with orthographic surgery.

Methods

Patients with ADD and jaw deformity from 2017 to 2021 were included. Disc repositioning by either open suturing or mini-screw anchor were performed simultaneously with orthognathic surgery. MRI and CT images before and after operation and at least 6 months follow-ups were taken to evaluate and compare the TMJ disc and jaw stability. ProPlan CMF 1.4 software was used to measure the position of the jaw, condyle and its surface bone changes.

Results

Seventeen patients with 20 hypoplastic condyles were included in the study. Among them, 12 joints had disc repositioning by open suturing and 8 by mini-screw anchor. After an average follow-up of 18.1 months, both the TMJ disc and jaw position were stable in the 2 groups except 2 discs moved anteriorly in each group. The overall condylar bone resorption was 8.3% in the open suturing group and 12.5% in the mini-screw anchor group.

Conclusions

Disc repositioning by open suturing can achieve both TMJ and jaw stability for hypoplastic condyles when combined with orthognathic surgery.

Modification to Yang's arthroscopic Discopexy Technique for Temporomandibular Joint disc Displacement. Technical Note

Disc displacement is a common disorder of the temporomandibular joint (TMJ) that often results in progressive joint dysfunction, including clicking, arthralgia, functional limitations, osteoarthritis, and even condylar resorption. Several arthroscopic techniques have been proposed to treat anterior disc displacement. Yang's arthroscopic disc repositioning and suturing technique, described in 2012, consist in a pair of sutures inserted through the junction of the disc and the retrodiscal tissue and tied underneath the cartilage of the external auditory canal. This technique is reported to be the most stable over time, but it has 2 main disadvantages, 1) it is one of the most challenging to perform, requiring a skill TMJ arthroscopic surgeon and 2) it needs a customized suture equipment. We designed a modification to Yang's technique using a common, cheap, available and disposable suture set.

The Efficiency of Different Arthroscopic Discopexy Techniques Based on Clinical and Radiographic Findings: A Systematic Review

ABSTRACT

The aim of this systematic review was to evaluate the effectiveness of different temporomandibular joint arthroscopic discopexy techniques.The systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and an electronic search was performed using MEDLINE (PubMed), The Cochrane Library, ScienceDirect databases using a combination of the terms "discopexy," "disc recapture," "disc fixation," and "temporomandibular joint" to identify clinical trials published from 2010.In total, 493 records were screened, of which only 9 fulfilled the inclusion criteria and were included in qualitative data synthesis.The results of clinical findings evaluation showed that arthroscopic discopexy statistically significantly improved levels of pain (VAS) and maximum interincisal opening whereas magnetic resonance imaging evaluation showed disc position improvement of up to 90% to 100%.In conclusion, this review provides the evidence of the potential benefits of arthroscopic disc fixation in the treatment of patients with internal derangements : reduced pain, increased maximum interincisal opening, and improved disc position evaluated by magnetic resonance imaging, whereas disc fixation using suturing techniques seems to be the most appropriate method.

Stability of the contralateral temporomandibular joint disk position after disk repositioning on one side

OBJECTIVE

To evaluate the stability of the contralateral temporomandibular joint disk position after disk repositioning on 1 side.

STUDY DESIGN

Patients with unilateral anterior disk displacement (ADD) treated by disk repositioning from 2015 to 2019 were included in the study. The contralateral disk status was classified as follows: normal, ADD with reduction (ADDwR), and medial/lateral displacement. At 1-year follow-up, changes in the contralateral disk position were evaluated by MRI.

RESULTS

Two hundred thirty-four patients were included in the study. There were 84 disks with normal position, 51 with ADDwR, and 99 with medial/lateral displacement (M/LD) in the contralateral joint. At 1-year follow-up, all the repositioned disks were stable without relapse. In the contralateral joints, 75% of the disks with normal position were unchanged compared with 43.1% of the ADDwR and 54.5% of the M/LD. ADDwR had the highest rate of changing to ADDwoR compared with the disks in normal position (4.8%) and M/LD (7.1%, χ² = 16.13, P < .001). There were 28.3% of M/LD disks and 3.9% of ADDwR that changed to normal position.

CONCLUSIONS

After unilateral disk repositioning, most of the contralateral disks with normal position were stable. M/LD disks tended to move to normal position, whereas ADDwR was largely changed to ADDwoR.

An arthroscopic technique for closure of perforations in temporomandibular joint retrodiscal tissues

The objective of this retrospective study was to introduce and evaluate an arthroscopic discopexy for closure of retrodiscal tissue perforations. A total of 112 patients (135 joints) receiving an arthroscopic discopexy for management of retrodiscal tissue perforations between January 2016 and September 2019 were included. Pre- and postoperative visual analogue scale (VAS) pain scores and maximum inter-incisal opening (MIO), as well as magnetic resonance imaging (MRI) data, were collected and analysed. Success was recorded when the disc position was >11 o'clock, VAS pain score <3, and MIO>25 mm. For patients with a condyle deformity, postoperative bone remodelling was also recorded. The VAS pain score decreased from 3.04 ± 2.66 preoperatively to 0.88 ± 1.13 at 12 months postoperatively (P < 0.001) and MIO increased from 33.90 ± 7.39 mm to 35.19 ± 6.14 mm (P = 0.029). MRI evaluation revealed that 133 discs were successfully repositioned back on top of the condyle. Among these, 11 joints were associated with either VAS pain score ≥3 or MIO ≤25 mm. Therefore, a success rate of 90.4% (122/135) was achieved at 12 months postoperative. Bone remodelling was detected in 72 joints. Arthroscopic discopexy is a minimally invasive and effective treatment for retrodiscal tissue perforations that achieves the purpose of simultaneously restoring the intra-articular structures and relieving clinical symptoms.

A randomized controlled preclinical trial on 3 interposal temporomandibular joint disc implants: TEMPOJIMS-Phase 2

The effort to develop an effective and safe temporomandibular joint (TMJ) disc substitute has been one of the mainstreams of tissue engineering. Biodegradable customized scaffolds could approach safety and effectiveness to regenerate a new autologous disc, rather than using non-biodegradable materials. However, it is still technically challenging to mimic the biomechanical properties of the native disc with biodegradable polymers. In this study, new 3D tailored TMJ disc implants were developed: (1) Poly(glycerol sebacate) (PGS) scaffold reinforced with electrospun Poly(εcaprolactone) (PCL) fibers on the outer surface (PGS+PCL); (2) PCL and polyethylene glycol diacrylate (PEGDA) (PCL+PEGDA); and (3) PCL. The TMJ implants were tested in a randomized preclinical trial, conducted in 24 black Merino sheep TMJ, perfoming bilateral interventions. Histologic, imaging, and kinematics analysis was performed. No statistical changes were observed between the PGS+PCL disc and the control group. The PCL+PEGDA and PCL groups were associated with statistical changes in histology (p = 0.004 for articular cartilage mid-layer; p = 0.019 for structure changes and p = 0.017 for cell shape changes), imaging (p = 0.027 for global appreciation) and dangerous material fragmentation was observed. No biomaterial particles were observed in the multi-organ analysis in the different groups. The sheep confirmed to be a relevant animal model for TMJ disc surgery and regenerative approaches. The PCL and PCL+PEGDA discs presented a higher risk to increase degenerative changes, due to material fragmentation. None of the tested discs regenerate a new autologous disc, however, PGS+PCL was safe, demonstrated rapid resorption, and was capable to prevent condyle degenerative changes.

Temporomandibular Disorders: Current Concepts and Controversies in Diagnosis and Management

Temporomandibular disorders (TMD) are a group of orofacial pain conditions which are the most common non-dental pain complaint in the maxillofacial region. Due to the complexity of the etiology, the diagnosis and management of TMD remain a challenge where consensus is still lacking in many aspects. While clinical examination is considered the most important process in the diagnosis of TMD, imaging may serve as a valuable adjunct in selected cases. Depending on the type of TMD, many treatment modalities have been proposed, ranging from conservative options to open surgical procedures. In this review, the authors discuss the present thinking in the etiology and classification of TMD, followed by the diagnostic approach and the current trend and controversies in management.

The magnetic resonance imaging evaluation of condylar new bone remodeling after Yang's TMJ arthroscopic surgery

To evaluate the post-operative condylar bone remodeling after the treatment of Yang's arthroscopic surgery. Consecutive cases from Jan 2017 to May 2018 that received Yang's arthroscopic surgery were included in this study, the TMJ MRI examinations were performed preoperatively and postoperatively (follow up for 1 year or more), and condylar bone remodeling was estimated. A total of 229 patients (29 male and 200 female) were included in the study, 161 patients had new bone formation, and the average age was 17.5 ± 2.1a. There was no new bone formation in 68 patients with an average age of 24.5 ± 0.7a. The percentage of new bone formation patients in 10-15 years of age was 94.33% and decreases as the age increases. In the position of new bone formation, the posterior slope of condyle was the most (129 joints), the second was the top of condyle (54 joints), the third was around condyle (33 joints), only 25 joints had new bone on the anterior slope of condyle. After TMJ arthroscopic surgery, the condyle has the ability to form new bone, and the younger the age, the stronger the ability of new bone formation. The formation of new bone was most in posterior slope and least in anterior slope of condyle.

Is Arthroscopic Disk Repositioning Equally Efficacious to Open Disk Repositioning? A Systematic Review

PURPOSE

Temporomandibular joint disc repositioning surgery is 1 of the treatment modalities used for treating anterior disc displacement of the temporomandibular joint. The procedure can be arthroscopic disc repositioning or open disc repositioning. This systematic review measured and compared the efficacy of arthroscopic and open disc repositioning procedures.

MATERIALS AND METHODS

The authors conducted a systematic review without meta-analysis by performing a literature search electronically and manually covering arthroscopic and open disc repositioning studies published up to July 2020 in Pubmed, Embase, and Cochrane databases. Surgical outcomes such as changes in maximal incisal opening (MIO) and pain scores, temporomandibular joint noises, diet consistency, malocclusion, and postoperative complications were extracted and analyzed.

RESULTS

A total of 28 studies were included in the review and split into those assessing open disc repositioning (n = 13) and those assessing arthroscopic disc repositioning (n = 15). The average age of the study patients in the included studies was 31.5 ± 6.8 years, and women represented 83.3% of the study population. Both arthroscopic and open disc repositioning showed to be efficacious in reducing pain and increasing MIO. Due to heterogeneity in study designs and data reporting between the studies, no quantitative analysis was performed, and the groups were not directly compared.

CONCLUSIONS

Both arthroscopic and open disc repositioning led to significant improvements in clinical outcomes based on pain scores and MIO. This study highlights the need for comparative studies of the 2 techniques with well-documented case selection including standardized diagnosis based on Wilkes stages and rigorous outcomes assessment including patient reported outcomes.

The effect of TMJ disk repositioning by suturing through open incision on adolescent mandibular asymmetry with and without a functional orthodontic appliance

OBJECTIVE

The objective of this study was to evaluate the effect of combined temporomandibular joint (TMJ) disk repositioning by suturing through open incision and orthodontic functional appliance (OFA) treatment for adolescents with mandibular asymmetry.

STUDY DESIGN

Adolescent patients (12-20 years old) with mandibular asymmetry combined with unilateral TMJ disk displacement without reduction were treated with disk repositioning by suturing through open incision with and without postoperative OFA. Magnetic resonance imaging and posteroanterior cephalometric radiographs (PA) were used to measure and compare the changes in condylar height, joint space, and menton deviation pre- and postoperatively.

RESULTS

Twenty-six patients were included in the study. Joint space was significantly increased postoperatively and new bone mostly formed at the superior or posterior superior part of the condyle after 6 to 18 months in all surgically treated joints. Fourteen patients with OFA had a significant increase in condylar height and menton deviation compared to 12 patients without OFA (2.29 ± 0.91 mm vs 1.22 ± 0.69 mm, P = .003; 4.56 ± 1.48 mm vs 2.01 ± 0.74 mm, P = .000).

CONCLUSIONS

Combined treatment with TMJ disk repositioning by suturing through open incision and OFA can promote condylar growth and correct mandibular deviation in adolescent patients. Postoperative OFA can maintain the increased joint space created by disk repositioning and promote new bone formation at the superior and posterior parts of the condyle.

Long-term clinical outcomes of arthroscopic discopexy with resorbable pins

INTRODUCTION

Discopexy using resorbable pins is an arthroscopic technique to treat internal derangement of the TMJ, restoring the normal relationship between disc, condyle, and temporal bone. The objective of our study was to assess the 5-year clinical outcome of a series of patients treated with this technique.

METHODS

A study was conducted on a series of patients who underwent arthroscopic discopexy using resorbable pins between January 2007 and February 2018. All the patients were refractory to conservative treatment and classified as Wilkes stage III. Clinical data were recorded at 1-year, 3-year, and 5-year visits. Pre- and postoperative evaluation parameters were: joint pain (VAS scale), mandibular movements (mm), and articular locking and clicking.

RESULTS

The study included 33 patients and the technique was performed in 38 joints. Mouth opening increased significantly with each visit after surgery compared with preoperative scores (mean value of 10.65 mm, p < 0.001), with the mean value increasing significantly at the 5-year visit in relation to the mean value obtained at the 3-year visit. Patients reported significant decreases in pain after surgery, obtaining VAS values of under 10 at the 5-year visit (mean improvement of 56.95 points, p < 0.001).

CONCLUSIONS

Discopexy using resorbable pins resulted in a good and stable clinical outcome at the long-term follow-up.

Endoscopically assisted fixation of the custom-made total temporomandibular joint prosthesis in TMJ Yang's system through a modified preauricular approach

This article describes the experience with the endoscopically assisted fixation of the customized total temporomandibular joint (TMJ) prosthesis in TMJ Yang's system only through a modified preauricular approach. Twenty patients (23 joints) treated with the custom-made total TMJ prosthesis were retrospectively recruited. An endoscopically assisted technique was used through a modified preauricular approach to fix the mandibular component for all these patients. These reconstructions were evaluated by surgical records, clinical examinations, and radiographic observations. All patients had successful fixation of the prosthesis. No patient had permanent weakness of the facial nerve and malocclusion or any other severe complications. The mean operative time was 111 min per joint (range, 85-133 min). The average surgical bleeding was 195 ml per side. The mean follow-up period was 16.2 months (range, 5-32 months). The mean scores were 8.3 for surgical satisfaction and 9.2 for scar healing evaluation. All patients experienced positive clinical outcomes, with a mean 75.2% reduction in pain and 53.7% increase in mouth opening with significant differences (P<0.05). The endoscopically assisted TMJ reconstruction with the customized prosthesis in TMJ Yang's system through the modified preauricular approach could produce good aesthetic and functional results.