# Applied Mechatronic: A Sensor-Based Modification of an External Fixator According to [PERSON]
## 5 Conclusions and Further Work  
Classical diagnostic approaches for determining full recovery after a long bone fracture do not provide precise information about whether the bone has healed completely. The assessment on fixator removal is mostly based on orthopedist's experience and X-ray images. Occasionally, after diagnostic tests indicated the healing process was supposed to be completed and the fixator should be removed, patients return to hospital because of discomfort, pain, and/or infection. A modified external fixator, according to [PERSON], provides the orthopedist with accurate data based on sensor measurements of change in the compressive force. Experiments with the modified external fixator were carried out using three distinct axial loads delivered by the UETM, which simulated patient's ability to lean to the leg until pain occurred, and a sensor that measured the resulting force. Springs of varying rigidity were used to imitate bone callus stiffness. Low rigidity springs depicted a high elasticity callus, whereas high rigidity springs replicated a callus with reduced elasticity and increased stiffness. The results showed that the force detected by the sensor was nearly identical to the force delivered by the UETM for k = 0 N/mm and decreased as spring rigidity increased. As the next research step, the modified external fixator according to [PERSON] is planned to be used in the clinical practice of medical co-authors in real-world situations. Furthermore, the modified external fixator is planned to be upgraded with communication equipment for remote data transmission of axial load measurements. Remote transmission eliminates the need for the orthopedist and the patient to be present at the same place during periodic check-ups. The benefits to the patient include enhanced comfort, reduced stress and a variety of others. The results on bending and axial compressive force over time provide information on the dynamics of callus hardening. These data can be used to build machine learning models, which could predict the patient's recovery time. In this way, it would be possible, for example, to estimate the costs of treatment, absenteeism from the workplace due to injury, and so forth. Artificial intelligence algorithms can also be used for data processing and decision-making. Given data can be integrated with digital health platforms to facilitate remote monitoring and data sharing. Data analysis could be later used for different medical applications. It is important to note that processing and transmitting personal data necessitate data protection, which implies the use of cryptographic algorithms. In some severe cases, where the bone must be stretched, a relative gradual axial separation of bone parts over time intervals with a distance proportional to the bone union may be performed. This can be accomplished by using screws built into the modified fixator to transform rotational movement into a rectilinear one. The screw can be tuned by orthopedist or automatically using a small, sensitive stepper motor actuator (SMA) at a specified angle to separate bone parts dependent on the angle of rotation and the step of the coil. SMA consists of a synchronous stepper motor that moves in discrete steps, a mechanical transmission mechanism that converts the motor's rotary motion into the linear motion, and a control system that manages the stepper motor operations. The communications protocols used to control stepper motors are IEEE 802.x, TCP/IP, and UDP. SMA control can be implemented using a variety of microcontroller chips with Wi-Fiinterfaces, such as Microchip PIC16F (Microchip Technology, Chandler, Arizona, USA) and Espressif System ESP 8266 (Espressif Systems, Shanghai, China). Last but not least, there is some possibility for using the modified external fixator on cattle's long bones to improve clinical management of selected fractures. However, it should be kept in mind that this structure should be customized to the specific use on livestock. Conceptualization, V.A., R.P., M.M. ([PERSON]), M.M.