Oral Presentation ANZBMS-MEPSA-ANZORS 2022

Three-dimensional kinematics of the jaw following unilateral and bilateral prosthetic TMJ surgery (#78)

Sarah Woodford 1 , Dale Robinson 1 , Peter VS Lee 1 , Jaafar Abduo 2 , George Dimitroulis 3 , David Ackland 1
  1. Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
  2. Melbourne Dental School, The University of Melbourne, Melbourne, Victoria, Australia
  3. Department of Surgery, St Vincent's Hospital, Melbourne, Victoria, Australia

OBJECTIVE

Total temporomandibular joint (TMJ) replacements reduce pain and improve quality of life in patients suffering from end-stage TMJ disorders, such as osteoarthritis and trauma. Jaw kinematics measurements following TMJ arthroplasty provide a basis for evaluating implant performance and jaw function. The aim of this study is to provide the first measurements of three-dimensional kinematics of the jaw in patients following unilateral and bilateral prosthetic TMJ surgeries.

METHODS

Jaw motion tracking experiments were performed on 7 healthy control participants, 3 unilateral and 1 bilateral TMJ replacement patients. Custom-made mouthpieces were manufactured for each participant’s mandibular and maxillary teeth, with each supporting three retroreflective markers anterior to the participant’s lip line. Participants performed 15 trials each of maximum jaw opening, lateral and protrusive movements. Marker trajectories were simultaneously measured using an optoelectronic tracking system. Laser scans taken of each dental plate, together with CT scans of each patient, were used to register the plate position to each participant’s jaw geometry, allowing 3D condylar motion to be quantified from the marker trajectories.

RESULTS

The maximum mouth opening capacity of joint replacement patients was comparable to healthy controls with average incisal inferior translations of 37.5mm, 38.4mm and 33.6mm for the controls, unilateral and bilateral joint replacement patients respectively. During mouth opening the maximum anterior translation of prosthetic condyles was 2.4mm, compared to 10.6mm for controls (Fig-1). Prosthetic condyles had limited anterior motion compared to natural condyles, in unilateral patients this resulted in asymmetric opening and protrusive movements and the capacity to laterally move their jaw towards their pathological side only. For the bilateral patient, protrusive and lateral jaw movement capacity was minimal.

CONCLUSIONS

Total TMJ replacement surgery facilitates normal mouth opening capacity and lateral and inferior condylar movements but limits anterior condylar motion. This study provides future direction for TMJ implant design.

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