You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Survey on Fall Detection and Fall Prevention Using Wearable and External Sensors 
Chapter Title:  Fall Prevention Systems 
1. Abstract of Cited Paper (BIB001):  This paper describes a foot age estimation system using fuzzy logic. The method employs sole pressure distribution change data. The sole pressure data is acquired by a mat type load distribution sensor. The proposed method extracts step length, step center of sole pressure width, distance of single support period and time of double support period as gait features. The fuzzy degrees for young age, middle age and elderly groups are calculated from these gait features. The foot age of the walking person on the sensor is estimated by fuzzy MIN-MAX center of gravity method. In the experiment, the proposed method estimated subject ages with good correlation coefficient.

Literature Review:
According to  , $43.8 billion dollars are estimated to be used in fall-related medical care expenditures by 2020. It is of extreme importance to find ways to minimize these costs, and at the same time, improve the quality of life of the people who suffer the consequences of a fall  BIB001 . The easiest way to accomplish this is through prevention. Educating and discussing the potential consequences of a fall with the patients constitute the principal method doctors and caregivers have in order to prevent falls. Although important, this solution is not enough, more non-patient dependent strategies must be considered. Care givers have to identify all of the scenarios and circumstances surrounding a fall and provide a framework to prevent them. This framework must be constructed based on data acquired from various scenarios surrounding fall-related events. Most of fall-related events are usually collected through questionnaires, fall diaries, and/or phone calls. Although these data collection practices do provide relevant information, the information is not always reliable. This happens because people often forget or remember incorrectly the exact conditions of their fall  . People do not just fall; there is always an underlying cause or risk factor involved in every fall. The more risk factors there are, the more a person is susceptible to experiencing a fall. Falls are roughly associated with three risks factors: environmental, physical, and psychological factors. The first, environmental conditions, are obstacles on the floor, climbing or descending stairways, slippery floors, etc. The physical factors are those related to a patient's body condition such as muscle weakness, gait balance, posture, sight, etc. Psychological factors deal with things that temporarily affect people's minds such as fever, alcohol, lack of attention, etc. Most of the times only psychological and physical falling factors are tackled BIB002 . The following sections expand on the aforementioned risk factors. The most relevant studies on fall prevention systems are described next.