Keys to an open lock: Subject specific biomechanical modelling of luxations of the human temporomandibular joint

In this thesis, the aims are to: • increase the understanding of the interplay of morphological aspects, such as joint shape and muscle orientation, in open locks of the human temporomandibular joint. • increase the understanding of the biomechanics behind open locks of the temporomandibular joint. The kinetics will be studied to provide insight in the net effect of the acting muscle forces and joint reaction forces and their resulting moments. • improve the level of detail of the biomechanical model, to allow for tailor-made models at a patient level. The first chapters will deal with the application of a biomechanical model to normal function and to open locks. Chapter 2 will deal with the normal opening and closing movement of the mouth and will focus on the differences in temporomandibular joint loading between opening and closing. A sensitivity analysis of critical model parameters will be included. In Chapter 3, the roles of joint morphology and muscle morphology are investigated in relation to open locks, as well as their potential interplay. Chapter 4 will investigate relaxation and laterotrusion activation strategies that might enable the lower jaw to get out of an open lock. In chapter 5, the predictions about morphological parameters for open locks from chapter 3 will be tested in patients with symptomatic hypermobility, and compared with healthy controls. The joint shape and muscle morphology from cone beam computed tomography (CBCT) scans will be used as input parameters to fine-tune the musculoskeletal model. Herewith, individualized musculoskeletal models can be obtained, and risk assessment for open locks can be performed at an individual level. In chapter 6, a general discussion will be held on the model as well as on the results from the patient study. Furthermore, a case report will be interpreted in the framework of the International Classification of Functioning, Disability, and Health (World Health Organization, 2001). Future directions for research will be discussed as well