# Survey on Video-Based Biomechanics and Biometry Tools for Fracture and Injury Assessment in Sports
## 1 Introduction
### Risk of Fractures and Injuries in Sports  
When microcrack formation exceeds bone remodeling, these accumulate and grow towards threshold lengths, which cause the formation of macro fractures consisting of measures approximating 1 mm, to provoke the final rupture through the bone cortex. In high-intensity sports, fatigue injuries compose 20% of the total injuries [8], while in the military, they can be as high as 31% [9]. These fractures locate mainly in the tibia and fibula in long-distance runners [10]. Tibia is the most frequently fractured bone during sports activities, after sustaining five to six times the body weight [11]. The sports where this type of fracture occurs more commonly are classical ballet, aerobics, tennis, basketball, football, volleyball. After tibial shaft (40.3%), the cases of fractures in athletes due to stress include rib (15.8%), metatarsal bone (9.7%), ulnar olecranon (8.2%), pubic bone (5.6%), fibular shaft (4.6%), tibial medial malleolus (4.1%), and other types of bones (11.8%) [12]. In general, ref. [13] reported metatarsal fatigue fractures to consist of 38% of all the bone stress injuries and even 58% in the military. Furthermore, studies have reported measurement and prevention of the development of stress fractures due to sports activities. Some of these include the analysis of using shock-absorbing insoles, basketball shoes, training modifications, and calcium supplements [14]. In soccer, the metatarsal bone has to be studied, and its risk for developing fatigue injuries. In this regard, refs. [15; 16] affirmed these types of fractures included almost 78% of all stress fractures that occurred in a European League from 2000 to 2009, involving refracturing in 27% of the cases, and even not full recovery in 14% of them. Hence, this type of injury can lead to high risks of a career-ending decision [17]. Moreover, several studies exist regarding the involvement of stresses in the fifth metatarsal region towards developing fatigue fractures. Among these, one of the first studies in football involving repetitive loading is presented in [18]. In this work, athletes developed fractures in the fifth metatarsal while performing kicking and cutting movements. Other studies include: plantar pressure influences the risk of injuries [19]; specific action against static motions for detecting discrepancies in lateral foot loadings [20]; plantar forces at the lateral forefoot between healthy and fractured players [21]; more tendency to fracture for the case of a non-preferred foot [22]; explanations regarding static plantar pressure measurements to be not efficient in assessing fatigue injury risks [23]; specific regions within the foot showing higher pressures in the non-preferred feet of football players [24]; longer fifth metatarsal and higher medial longitudinal arch in the case of fractured against healthy players [25], among other studies. In [26], authors reported analysis regarding the use of deterministic models to study biomechanics to improve movement performance and injury risk reduction. This type of models help to determine the relationship between a movement outcome measurement and the biomechanical parameters involved in such measure. Typically, block diagrams and equations are used to understand the relationship of variables, and provide its numerical representation respectively [26]. Another work makes use of video processing software, with a front and lateral view analysis in stroke to highlight errors towards proper instruction and minimize injury risk [27]. A study focused on the shoulder biomechanics in swimming [28] concluded supraspinatus tendinopathy was the most common cause of shoulder pain, suggesting that a proper evaluation involves the entire kinetic chain. Another relevant study regarding the inclusion of strategies for the prevention and treatment focusing on swimmers' shoulders is presented in [29]. Other research studies involving swimming biomechanics analysis are included in Table 1.