Two-Axis Continuous Distractor for Mandibular Reconstruction

Abstract

The application of Distraction Osteogenesis (DO) techniques in the reconstruction of skeletal deficiencies is a relatively new topic in the fields of oral and maxillofacial surgeries. In many reconstruction applications, using DO is the preferred technique, as opposed to conventional reconstruction techniques, as there are more advantages and fewer side effects when it is used. The first generation of DO devices is made up of manual distractors that can apply an intermittent distraction force to the bone segment during the distraction process. Manual DO techniques have shown the functionality of the DO technique. Further research has recently been performed on the development of automatic devices for generating a controlled continuous force. However, the existing automatic techniques have limitations, and are yet to be used in reconstruction applications in humans. There is still a gap between the developed techniques and an ideal distractor to be used in mandibular reconstruction surgeries. In this research, a two-axis continuous distractor is proposed for use in mandibular reconstruction applications. The proposed distractor can generate two continuous distraction forces that can be applied to two independent distraction vectors. The proposed device can perform the standard distraction process using the predetermined distraction factors. The control system has a high positioning accuracy and resolution in controlling the position of the intra-oral end effectors while applying two continuous forces for moving the bone segment. The proposed two-axis continuous distractor meets the current requirements, and can be used as an ideal continuous DO device for different mandibular reconstruction applications.

Keywords: bone regeneration; distraction osteogenesis; maxillofacial reconstruction.

Figure 1

Oral and maxillofacial reconstruction techniques and the existing DO methods.

Figure 2

Illustration of the application of manual distractors in MRAs: (A) extra-oral distractor; (B) intra-oral distractor.

Figure 3

TB distractor with manual activation for reconstruction of mandibular retrognathia [45].

Figure 4

Reconstruction of mandibular retrognathia using BB and TB distractors: (A) Normal Mandible; (B) Reconstruction of mandible using BB distractor; (C) Reconstruction of Mandible using TB distractor.

Figure 5

The detailed design of the control system.

Figure 6

The schematic design of the mechanism for generating and transmitting two independent continuous forces with the end-effector-controlled positioning.

Figure 7

Intra-oral single-stage cylinder, and BB and TB end effectors for different MRAs: (A) intra-oral hydraulic cylinder; (B) BB end effectors; (C) TB end effectors.

Figure 8

The mathematical model of the designed control system.

Figure 9

The first prototype of the two-axis automatic continuous distractor.

Figure 10

Simulation results of the modeled control system and stepper motor: (A) phase voltage; (B) phase current; (C) rotor speed; (D) rotor position.

Figure 11

The experimental tests: (A) measuring the generated pushing force via linear mechanism; (B) measuring the transmitted force (i.e., DF); (C) linear positioning of the carriage of the linear mechanism; (D) linear positioning of the end effector.

Figure 12

Battery discharge test: (A) the test procedure; (B) the obtained results.

Figure 13

Illustration of the application of two-axis continuous distractor in MRAs using mandible models: (A) intra-oral BB end effectors; (B) intra-oral TB end effectors.