## 1 Introduction  
Proximal humerus fractures are becoming more frequent in older adults [1], caused by the motor deficiencies and the poor bone quality that the natural aging process brings with it [2]. These fractures are difficult to treat due to the complex union of the shoulder and the variations that the fracture can present [3]. Due to the abovementioned factors, the choice of treatment is based on the characteristics of the patient and the fracture [4]. However, the surgical treatment that today presents the best results is osteosynthesis using a locking plate [5] despite the risks involved and the increase in its failure rate.  
In search of treatment optimization, the scientific community directed its studies to the assessment of the factors considered significant to the stability of the fracture [6, 7]. Thus, the relevance of the locking plate configuration and its effect on the bone-healing process of the fracture was discovered [8, 9]. One of the most interesting parameters is the configuration of the screws used for locking plate fixation [4].  
The general problem is the rise in the rate of premature failures that occur in locking plate osteosynthesis treatment for proximal humerus fractures that ends up directly affecting the quality of life of geriatric patients who receive the treatment [1].  
The specific problem is the absence of an optimal configuration regarding the angle of insertion of the screws used in the osteosynthesis treatment using a locking plate that results in low stability of the fracture during treatment. Finding the optimal configuration considering mechanical and anatomical limitations of the human body supposes an increase in the stability of the fracture and its fixation that will result in the prevention of premature failures of the treatment and in the improvement of the quality of life of patients [10].  
The scientific community has assessed the most significant parameters in relation to the configuration of the locking plate and its effect on the stability of the fixation system [11]. Being a complex and changing system due to singularities of both the patient (age, comorbidities, bone quality, sex, etc.) and fracture type (location of the fracture, presence of impaction, comminution, displacement, etc.), the knowledge necessary to strengthen the stability of the system has not been totally covered considering the existing research [3].  
Among the most relevant studies carried out by researchers with the purpose of perfecting the treatment are: the assessment of the effect of material type with which the blocking plate was manufactured, the differences generated by the different types of screws, the importance of the use of calcar screws, the effect on system stability caused by the type of screw hole in the locking plate, improvement of the fatigue performance of high cycle materials by cryogenic treatment and the prediction of premature system failure by determining the optimal number of screws for treatment [5; 7; 12; 13; 14; 15].  
This research offers a new biomechanical approach to solve the problem. Determining the optimal screw insertion angle configuration used in the locking plate to treat two-part proximal humerus fractures [16], significant stability in fracture fixation will be achieved by obtaining the appropriate percentage of interfragmentary deformation of the fractured segments that benefits the natural process of bone consolidation of the fracture [17; 18].