Custom-made Total Joint Replacement for the Management of Recurrent Bilateral Temporomandibular Joint Ankylosis - A Retrospective Study

Abstract

Introduction:

Recurrent bilateral temporomandibular joint (TMJ) ankylosis poses a significant challenge due to limited treatment options and extensive functional impairment. Alloplastic total joint replacement (TJR) represents a potential solution, particularly custom-made devices that allow for precise anatomical reconstruction. However, data on the efficacy of custom-made TJR in this specific population remains limited. This study aimed to evaluate the functional outcomes of custom-made alloplastic TJR in managing recurrent bilateral TMJ ankylosis. Specific outcomes assessed include maximal incisal opening (MIO), postsurgical malocclusion, heterotopic bone formation and dietary restriction patient satisfaction.

Materials and Methods:

This study was a retrospective study on six patients who underwent custom-made alloplastic TJR for recurrent bilateral TMJ ankylosis at a single institution. Preoperative and postoperative MIO and dietary restrictions were evaluated. Radiographic assessments, complications, patient satisfaction and quality of life after surgery were documented.

Results:

Custom-made TJR resulted in a significant increase in mean MIO from 5.5 mm (standard deviation [SD]: 5.54 mm) preoperatively to 35.17 mm (SD: 2.99 mm) at 1-year follow-up. All patients demonstrated improvement in dietary restrictions. The radiographic assessment showed stable prostheses. No major complications were observed, and all patients reported satisfaction with the surgical outcome.

Discussion:

This study suggests that custom-made alloplastic TJR is a viable treatment option for patients with recurrent bilateral TMJ ankylosis, leading to substantial improvements in mouth opening, pain reduction and overall function. Larger, prospective, multi-centre studies are needed to confirm these findings and further evaluate the long-term outcomes.

INTRODUCTION

Temporomandibular joint (TMJ) ankylosis is a debilitating condition characterised by the partial or complete immobilisation of the jaw due to the abnormal fibrous or bony fusion between the mandibular condyle and the glenoid fossa [Figures 1 and 2]. This condition adversely impacts mastication, speech, the maintenance of oral hygiene and the performance of daily living activities.[1] Aetiologies include trauma, infection, systemic arthritis or congenital factors.[2] Surgical intervention is necessary for the management of TMJ ankylosis, including procedures such as gap arthroplasty, interpositional gap arthroplasty and total joint reconstruction, which may involve the use of either autologous or alloplastic materials.[3] However, the surgical management of this condition is particularly challenging due to the altered anatomy and the close proximity of vital structures, including the middle cranial fossa, middle ear and branches of the facial nerve.[4]

Figure 1.

Preoperative photo showing the limited mouth opening

Figure 2.

Preoperative three-dimensional computed tomography scan showing bilateral temporomandibular joint ankylosis

Recurrent ankylosis, the redevelopment of ankylosis after prior surgical intervention, can occur at rates as high as 50% and presents a significant challenge.[5] The cumulative effects of previous surgeries, such as increased scarring, distorted anatomy and limited tissue availability, result in progressively more complex and less effective procedures. Bilateral recurrent cases are even more complex, often necessitating more extensive procedures, longer operative times and carrying a higher risk of complications.

Traditional surgical procedures such as gap arthroplasty, interpositional arthroplasty and even costochondral graft reconstruction are often insufficient for recurrent cases. In this context, total joint reconstruction with an alloplastic prosthetic device comes into view.[6] Two types of alloplastic prostheses are available: stock and custom-made.[7] The advantages of stock prostheses include lower cost and simpler preoperative preparation.[8] Custom-made prostheses, on the other hand, utilise computer-aided design/computer-aided manufacturing (CAD/CAM) technology for precise, single-stage implantation, tailored to the patient’s anatomy. However, these prostheses come at a higher cost.[9]

Many studies have explored the role of stock joint replacements in treating primary or unilateral TMJ ankylosis.[10] However, there is limited data available on the application and effectiveness of custom-made prostheses in treating TMJ ankylosis, particularly recurrent and bilateral cases. The present study is designed to retrospectively evaluate the functional outcomes, including maximal incisal opening (MIO), postsurgery malocclusion, complications (infection, joint pain and heterotrophic bone formation) and patient satisfaction, following custom-made alloplastic total joint replacement (TJR) for recurrent bilateral TMJ ankylosis.

MATERIALS AND METHODS

This is a retrospective study, reviewing the medical records of all patients who underwent custom-made alloplastic TJR for recurrent bilateral TMJ ankylosis at our department between February 2019 and August 2023. The study was approved by the Institutional Review Board (IRB number: 04-2025-300575) and conducted in accordance with the Declaration of Helsinki (2013). Written informed consent was obtained from all patients. The inclusion criteria were (1) patients diagnosed with recurrent bilateral TMJ ankylosis who had undergone at least one prior surgical procedure for TMJ ankylosis, (2) skeletally mature patients and (3) a minimum postoperative follow-up of 12 months. The exclusion criteria were (1) patients with severe systemic illness, infection at the operation site or unfit for surgery and (2) patients with a history of alloplastic prosthesis allergy.

All patients received custom-made alloplastic prostheses designed specifically to fit the bone details of each patient using CAD software based on the patient’s anatomical data. The prostheses were fabricated from titanium alloy for the condylar component and ultra-high-molecular-weight polyethylene for the fossa component [Figure 3]. Virtual surgical planning (VSP) was performed to simulate the resection of the ankylosed mass and placement of the prosthesis.

Figure 3.

Custom-made temporomandibular joint prosthesis components: (a) condylar component, (b) fossa component and (c) patient-specific cutting guide. The size and orientation vary between the right and left sides to ensure precise anatomical adaptation to the patient’s bone

A preauricular incision extended to the temporal region was used to expose the joint and enter into the fossa. A Risdon’s incision enabled insertion of the cutting guide, which was fixed to the mandibular ramus. This was resected to release the ankylotic bones and the cutting guide was removed. The fossa component was inserted first and secured with four to five 2.0 mm titanium screws. The ramal component was then inserted and rigidly fixed with five to six 2.7 mm bi-cortical screws. Mouth opening was checked and an opening of approximately 30–40 mm was estimated to be satisfactory. The surgical sites were then closed in layers [Figure 4].

Figure 4.

Intra-operative photos: (a) Scar from previous surgery, (b) Callus from previous surgery, (c) View of fixed alloplastic joint

The patient was administered two weeks of broad spectrum antibiotics. The patient also received regularly scheduled nonsteroidal anti-inflammatory drugs. Immediate postoperative 3D-CT and panoramic radiographs were obtained [Figure 5]. These were repeated at three and 12 months. The patient was advised an initial soft diet with a shift to regular diet as advised. Follow-up visits were at 2 weeks, 1 month, 4 months, 6 months and 1 year [Figure 6] to evaluate the maximum interincisal opening measured in millimetres [mm], malocclusion, complications (infection, joint pain and heterotrophic bone formation) and patient satisfaction.

Figure 5.

Postoperative three-dimensional computed tomography scan at 1 year showing the prosthesis in place

Figure 6.

Clinical follow-up photos. (a) Postoperative photo at 6 months showing maximal incisal opening (MIO) about 35 mm, (b) Postoperative photo at 1 year showing MIO about 36 mm

Data were analysed using SPSS software (Version 25.0; IBM Corp., Armonk, NY, USA). Continuous variables were presented as mean ± standard deviation (SD). Pre-and postoperative changes in MIO were compared using a paired Student’s t-test. P < 0.05 was considered statistically significant.

RESULTS

Six patients (four females, two males; mean age 34.6 years, range 22–57 years) met the inclusion criteria and underwent bilateral custom-made alloplastic TJR between February 2019 and August 2023, yielding a total of 12 prostheses. Demographic and clinical characteristics are summarised in Table 1. The mean preoperative MIO was 5.5 mm (SD ± 5.54). Postoperative mean MIOs were 33.3 mm (SD ± 6.12) on day 1, 32.7 mm (SD ± 2.7) at 2 weeks, 34.3 mm (SD ± 2.4) at 3 months, 34.7 mm (SD ± 2.94) at 6 months and 35.2 mm (SD ± 2.99) at 12 months [Table 2 and Figure 7]. The mean increase in MIO at 1 year was 29.7 mm (SD ± 6.16), which was statistically significant (P < 0.001, paired t-test) [Figure 8].

Table 1.

Demographic and clinical characteristics of the patients

Patient number	Sex	Age (years)	Previous surgical procedure	Preoperative maximum incisal opening(mm)
1	Female	22	Gap arthroplasty with costochondral graft	7
2	Male	36	Gap arthroplasty	14
3	Female	24	Gap arthroplasty	0
4	Female	39	Gap arthroplasty with costochondral graft	0
5	Female	30	Gap arthroplasty	3
6	Male	57	Gap arthroplasty with temporalis interpositional flap	9

Table 2.

Preoperative and postoperative maximal incisal opening

Patient number	Maximum incisal opening (mm)
	Preoperative	Postoperative
		Day 1	2 weeks	3 month	6 month	1 year
		1	7	31	30	30	31	34
2	14	22	32	36	34	35
3	0	38	32	36	32	30
4	0	38	36	36	38	38
5	3	35	30	33	35	36
6	9	36	36	35	38	38
Mean±SD	5.5±5.54	33.67±6.13	32.67±2.7	34.33±2.4	34.66±2.94	35.16±2.99

SD: Standard deviation

Figure 7.

Maximum interincisal opening on preoperative day and on postoperative day 1, 2 weeks, after 3 months, 6 months and 1 year

Figure 8.

Line graph for the mean maximal incisal opening values over time

Two patients developed transient weakness of the upper branches of the facial nerve; one case was bilateral. These were presented as reduced forehead wrinkling and incomplete eye closure. Both resolved completely within three months with conservative management and physiotherapy. One patient developed a postoperative open bite, successfully managed with traction elastics, achieving good occlusion at three months. There were no recorded cases of surgical site infection, persistent joint pain or neurosensory affection related to the inferior alveolar nerve.

Postoperative radiographic imaging (Orthopantomogram and cone beam CT scans) revealed that all prostheses were well-positioned. At 12 months, there was no evidence of prosthesis loosening or heterotopic ossification (HO) around the prosthetic components.

Postoperative 3D-CT and panoramic imaging confirmed the appropriate positioning of all prostheses. At 12 months, no evidence of prostheses loosening, screw failure, bone resorption or HO around the prosthesis’s components. All six patients were satisfied with the surgical outcomes and reported marked improvement in quality of life. By 12 months, all had transitioned to a normal diet, overcoming the severe restrictions experienced preoperatively.

DISCUSSION

Recurrent TMJ ankylosis presents unique challenges due to distorted anatomy that makes it difficult to identify key landmarks, dense scarring that makes layered dissection challenging and reduced ramal height that makes reconstruction more difficult. The residual ramus may be too short to accommodate standard prosthetic components, leading to intraoral exposure of the ramal component.[8]

Traditional treatment procedures such as gap or interpositional arthroplasty and costochondral grafting often fail in recurrent cases, with re-ankylosis rates reported up to 50%.[3] In contrast, TJR using alloplastic prostheses maintains the created gap and restores function while avoiding donor site morbidity and prolonged surgical time.[11,12]

Stock prostheses are available in three limited sizes (45 mm, 50 mm and 55 mm), and are not tailored to individual anatomical variations, which may not accommodate patients with smaller or deformed jaws or those with decreased ramal height secondary to previous surgery, leading to improper fit and potential complications like intraoral exposure.[3] Custom-made prostheses, fabricated with CAD/CAM and VSP, provide an individualised fit, improving stability and reducing risks of malposition or exposure.[13] Recent reports confirm the growing role of custom prostheses in complex ankylosis cases. For example, Rauniyar et al.,[1] highlighted the predictable outcomes of alloplastic replacement in recurrent ankylosis, while Franco et al., demonstrated superior biomechanical performance of custom devices under functional loading.[14]

The results of this study show an increase in mandibular opening from the preoperative average of 5.5 mm to an average of 33.67 mm on postoperative day 1. This initial improvement stabilised and slightly increased to a mean of 35.17 mm at 1 year. These results indicate the effectiveness of custom-made TJR in addressing the mechanical restrictions of the ankylosed TMJ and restoring clinically useful jaw mobility for patients who had already undergone surgical treatment. The occlusion remained stable in five patients, while one patient developed an open bite, which subsequently resolved with conservative management.

There was a clinically notable change in dietary restrictions from a restricted dietary intake (liquid diets) to either normal dietary intake or slight restriction. This further highlights the benefit of custom-made alloplastic TJR in restoring TMJ function, which is a major quality-of-life aspect for patients. The radiographic findings of well-positioned prostheses with no signs of loosening or bone resorption at 12 months are encouraging. The lack of significant HO is also positive and implies that the custom-made prosthesis has a reduced risk of recurrence due to HO; however, longer-term data would be necessary to further confirm this finding.

Transient facial nerve paresis occurred in two of our six patients (as one case was bilateral). This presented as a temporary weakness of the temporal and zygomatic branches. This is a well-documented risk in any surgery utilising a preauricular approach, with reported rates of transient weakness ranging from 1% to 32% in primary TMJ surgeries.[15] The risk is significantly elevated in recurrent ankylosis cases due to extensive scarring and distorted anatomical planes from previous interventions, which makes dissection more challenging and increases the likelihood of nerve traction or neuropraxia. In our cases, the paresis resolved completely within 3 months with conservative management, including physiotherapy and observation, which is consistent with nerve traction rather than permanent damage. The use of custom-made prostheses does not inherently reduce this specific risk, as it is related to the surgical approach itself rather than the implant.

One patient developed a postoperative open bite. This is a known potential finding following TJR, and its management is crucial for a successful functional outcome. Gerbino et al.,[9] reported stable occlusion in nine of their twelve cases, a rate comparable to our finding of five of six stable cases. An open bite can result from several factors, including improper seating of the fossa component, premature posterior occlusal contacts or muscular incoordination. This case was managed conservatively with traction elastics and achieved good occlusion 3 months postoperatively. This indicates that the fossa and ramal components are appropriately adapted and positioned; the issue appears to be secondary to muscle incoordination.

In our study, we did not encounter any major complications that are often reported with alloplastic joint replacement. There were no cases of surgical site infection. This is a significant finding, as infection of an alloplastic implant can be a catastrophic event, often necessitating implant removal. We attribute this success to our strict perioperative protocol, including meticulous aseptic technique and broad-spectrum antibiotics. We also recorded no neurosensory deficits of the inferior alveolar nerve, which we attribute to the precision afforded by the patient-specific cutting guides used during the ramal osteotomy and precise anatomical screws insertion away from the nerve canal, another advantage of the custom-made prosthesis. Finally, we recorded no signs of prosthesis loosening or mechanical failure. The excellent adaptation of the custom-made prostheses allows for ideal screw placement into the best available host bone. While our 1-year follow-up is encouraging, longer-term studies are essential to confirm the longevity and continued stability of these custom-made devices.

The self-reported data from patients showed that they are satisfied with the results of the surgery and the improved quality of life and function. This subjective data is just as important as the objective clinical data when evaluating the long-term outcome. Although total alloplastic TMJ reconstruction has a long history, there is limited literature on its use for recurrent bilateral TMJ ankylosis. Treating recurrent bilateral cases is more complex than single or primary cases. The limited research on alloplastic TJR for recurrent bilateral TMJ ankylosis makes it challenging to compare our results with other studies. This study adds a valuable contribution to an area that has been minimally studied. However, in comparison with studies using alloplastic TJR for primary ankylosis, Hu et al.,[16] in a study of 11 patients with TMJ ankylosis found a mean preoperative mouth opening of 5.5 mm and a mean postoperative mouth opening of 31.5 mm. Gerbino et al.,[9] also found that occlusion remained unchanged in nine out of 12 cases.

The limitations of this study include a relatively small sample size, retrospective nature, lack of a control group and a 1-year follow-up period. Longer-term follow-up is necessary to more accurately assess prosthesis durability, functional stability and the risk of late complications.

CONCLUSIONS

Recurrent TMJ ankylosis poses significant challenges due to anatomical distortion, fibrosis and limitations of available prosthetic devices. While stock prostheses are limited in size and customisation, custom-made alloplastic implants offer better anatomical accuracy and functional outcomes. TJR, particularly with custom prostheses, is increasingly recognised as the most effective solution for recurrent TMJ ankylosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.