Total prosthetic replacement of the temporomandibular joint

# Recommendations
Current evidence on the efficacy and safety of total prosthetic replacement of the temporomandibular joint is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.
Patient selection should be carried out in specialist units by a team with regular practice and specific expertise in the conservative and surgical management of temporomandibular joint problems, and should include consideration of all relevant medical and surgical options. The British Association of Oral and Maxillofacial Surgeons (BAOMS) has produced guidelines on patient selection.
The procedure should be carried out only by clinicians with specific training and experience in total prosthetic replacement of the temporomandibular joint.
Clinicians should submit details on all patients treated by total prosthetic replacement of the temporomandibular joint to the British Association of TMJ Surgeons UK register. Further information about the longterm safety and efficacy of the various prostheses used would be useful.# Indications and current treatments
Causes of disorders of the temporomandibular joint include inflammatory and degenerative arthritis, trauma, infection and complications of surgery. Symptoms include pain and difficulty opening and closing the mouth, and an inability to eat a normal diet.
Conservative treatments for disorders of the temporomandibular joint include rest, nonsteroidal antiinflammatory drugs, bite splints and physiotherapy. Surgical options include arthroscopic surgery, remodelling of the joint surface, removal of the intraarticular disc and replacement of components of the joint such as the disc, the fossa (socket) or the mandibular condyle.# The procedure
Total prosthetic replacement of the temporomandibular joint is considered when alternative treatments have failed. It involves replacing both the skull base component (the fossa or socket) and the condyle with prostheses. The aims of the procedure are to reestablish function of the temporomandibular joint and to relieve pain.
With the patient under general anaesthesia, an incision is made anterior to the ear for insertion of the fossa component, with a second incision behind or below the mandible for insertion of the mandibular condyle component. The coronoid process of the mandible is sometimes removed to allow more mobility after surgery.
A number of different prostheses are available for this procedure.# Efficacy
This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
A case series of 300 patients reported significant improvements in mean pain score (measured by visual analogue scale ranging from 0 to 5 with higher scores indicating more severe pain) from 1.18 at baseline to 0.03 at 1month followup and 0 at 6month followup (p<0.001 and p<0.0001 respectively). A case series of 288 patients reported significant improvements in mean pain scores (measured by visual analogue scale ranging from 0 to 10 with higher scores indicating worse pain) from 8.0 at baseline to 2.6 at 3year followup (p<0.0001). A case series of 74 patients, using similar methods, reported a change from 7.2 at baseline to 0.8 at 1year followup (p<0.0001).
The case series of 300 patients reported that mean diet score (measured by visual analogue scale ranging from 0 to 5 with lower scores representing a more restricted diet) improved from 2.16 at baseline to 4.96 at 1year followup (n=300, p<0.0001). After 6 months, 80% (240/300) of patients reported a general diet with no limitations. At 5 and 7year followup, the scores were 4.95 (n=166) and 4.93 (n=77) respectively. The case series of 288 patients reported improvements in mean diet score (measured by visual analogue scale ranging from 0 to 10 with 0 representing a normal diet and 10 representing liquids only) from 8.2 at baseline to 2.5 at 3year followup (p<0.0001). The case series of 74 patients reported improvements in mean diet score (measured by visual analogue scale ranging from 0 to 10 with 0 representing liquids only and 10 representing a normal diet) from 3.8 at baseline to 9.3 at 1year followup (p<0.0001).
A nonrandomised comparative study of 36 patients treated by total joint replacement or interpositional arthroplasty reported that the mean maximum interincisal opening improved from 15.6 mm and 10.3 mm at baseline to 24.9 mm and 28 mm, respectively (p=0.02 between the groups for the change from baseline), after the procedure (median followup of 12 months). The change in maximum interincisal opening was not significantly different between the 2 groups after adjusting for institution, the number of previous operations, laterality, age and aetiology (p=0.056).The case series of 300 patients reported that the mean maximum interincisal opening improved from 11.3 mm at baseline to 38.9 mm at 1year followup (n=300, p<0.0001). The maximum interincisal opening increased significantly at all followup intervals during the 3year period after surgery, with no significant changes from the fourth year onwards. The 2 case series of 288 and 74 patients reported significant improvements in mean maximum interincisal opening from 20.4 mm and 22.4 mm respectively at baseline to 29.5 mm (at 3year followup) and 33.7 mm (at 1year followup) respectively (p<0.0001).
The case series of 300 patients reported that mean function and speech scores (measured by visual analogue scale ranging from 0 to 5 where 0 represents no function and 5 represents optimal condition) improved significantly from 2.84 at baseline to 4.8 at 1year followup (n=300, p<0.0001). At 5 and 7year followup, the scores were 4.97 (n=166) and 4.92 (n=77) respectively. After 1 year, 85% of patients had an optimal score with regard to their speech and jaw movement capacity.
The case series of 288 patients reported that 46% of patients were enthusiastic about the procedure, 32% were very satisfied, 20% were satisfied and 2% were dissatisfied; 99.5% of patients reported that they would have the surgery again. The case series of 74 patients reported that 96% (71/74) of patients were very pleased with the procedure, 3% (2/74) were ambivalent and 1% (1/74) were dissatisfied.
The specialist advisers listed key efficacy outcomes as improvement in pain, improved eating ability scores and improvement in mouth opening.# Safety
This section describes safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
Blood transfusion was needed in 3% (2/74) of patients in the case series of 74 patients: in 1 patient, the neck had to be opened to control bleeding by ligating the terminal branches of the external carotid artery.
Temporary weakness of the temporal branch of the facial nerve was reported in 31% (23/74) of patients in the case series of 74 patients (this resolved within 6 months in all but 1 patient, who needed a brow lift because of longterm weakness). Temporary marginal mandibular palsy was reported in 11% (8/74) of patients (resolved within 6 months), and total facial palsy was reported in 3% (2/74) of patients (resolved within 6 weeks). Sensory changes to the lip and tongue were reported in 4% (3/74) of patients (resolved within 6 weeks). Longterm sensory loss to the distribution of the auriculotemporal nerve was reported in 14% (10/74) of patients.
Infection was reported in 2% (44/2106) and 3% (numbers not reported) of patients treated using different prostheses in a review of 2620 patients. Three per cent (14/442) of implants had 1 or 2 components removed because of heterotopic bone formation or infection in the case series of 288 patients. Infection was reported in 3% (2/74) of patients in the case series of 74 patients: the device was removed in both patients (with successful subsequent revision using a new prosthesis).
Dislocation of the prosthesis was reported in 1% (14/2106) of patients in the review of 2620 patients (no further details were reported). Dislocation of the prosthesis within a few hours of the operation was reported in 1 patient in the case series of 74 patients. This was treated by light elastic intermaxillary fixation for 1 week; the dislocation did not recur and the patient had a successful outcome at 1 year.
Malocclusion, malposition or displacement of the prosthesis was reported in 1% (19/2106) of patients in the review of 2620 patients (management not described).
Reoperation, sensitivity to material, fractured component, fractured bone screw, dehiscence or perforation, heterotopic bone or scarred tissue formation, and loosening of a component were each reported in less than 1% of patients in the review of 2620 patients.
The specialist advisers listed anecdotal adverse effects as changes in hearing, damage to the middle cranial fossa structures, early prosthetic failure and Frey's syndrome (gustatory sweating).# Further information
For related NICE guidance see the NICE website.

# Information for patients
NICE has produced information on this procedure for patients and carers. It explains the nature of the procedure and the guidance issued by NICE, and has been written with patient consent in mind.
ISBN 9781473106956