In-vivo kinematic assessment of alloplastic temporomandibular joint replacements by means of helical axis: A cohort study with historical control

Alloplastic total temporomandibular joint replacement (TJR) is a surgical procedure used to restore normal mandibular function when conservative therapies fail. The instantaneous helical axis (HA), mathematical model visualize globally rigid body kinematics. It can be applied motion for quantification of movement patterns and irregularities. Aim this study was analyze HA pathways in subjects with unilateral bilateral TJR compare them control group. An optoelectronic system employed track mouth opening/closing cycles (n = 3) 15 patients (7 operated unilaterally, 8 bilaterally, 11 F, aged 24–72) 12 controls (6 23–40). position space determined 30 equally-distributed steps the observed movement. Total rotation around (? tot ) translation along (T were determined. Angles between anatomical coordinate head (? x , ? y z ); global fluctuation spatial orientation e ), distance condylar center (CP) (d CP its projections on axes (x dCP calculated. Overall, ? larger than bilaterally (p 0.002, p 0.003) ?z unilaterally 0.004) 0.024). During opening, ¯ smaller 0.01). d alloplastic joints < 0.01 overall). In conclusion, differ significantly from terms location variability.