# Hand Joint Hypermobility among Dental Students--A Cross-Sectional Study
## 1 Introduction  
Joint hypermobility is defined as movement of the joint beyond the normal range of motion [1, 2]. Several causes contribute to its etiopathogenesis. One of the primary reasons is attributed to abnormalities in collagen, a protein responsible for the flexibility and strength of joints, ligaments, and tendons [1, 3]. Collagen dysfunction can arise from genetic mutations affecting the genes responsible for the structure, composition, or function of connective tissues [3, 4]. Syndromes such as Ehlers-Danlos syndrome (EDS) and Marfan syndrome are examples of collagen disorders in which joint hypermobility serves as a primary manifestation [3]. Hormonal changes, such as those occurring during pregnancy or the menstrual cycle, can also contribute to joint hypermobility status [5]. Additionally, joint hypermobility may result from previous joint injuries that caused damage to ligaments or the joint capsule, such as sprains or dislocations [5]. Muscle imbalance can furthercontribute to joint hypermobility if the supporting muscles are unable to provide sufficient stability [5]. The list of the negative consequences of having joint hypermobility is extensive. First of all, the most prominent effect is joint instability, which increases an individual's susceptibility to subluxations, as well as partial or complete dislocations with a subsequent impairment of their quality of life [6]. Other signs and symptoms are chronic musculoskeletal pain, fatigue, muscle weakness, and joint degeneration [4; 6]. Additionally, the severity of hypermobility can increase the likelihood of connective tissue injuries and damage, leading to conditions such as grains, strains, and tendonitis [6]. A recent classification has categorized joint hypermobility as generalized (i.e., multiple large joints involved, including axial joints, as well as upper and lower limbs), localized (i.e., between one and five joints involved), and peripheral (i.e., limited to the hands and/or feet) [6]. Epidemiological studies on the general population have revealed a prevalence ranging from 2 to 57% [7]. These numbers tend to increase when specific populations are considered, such as young children, individuals with EDS, specific ethnic groups (i.e., Asian, Middle Eastern, or African descent), females, and dancers, among others. Nevertheless, this condition is often underdiagnosed and undertreated, especially in certain patient populations [5]. For example, a study conducted on a university cohort reported that up to 75% of 335 students exhibited some form of joint hypermobility [4]. Studies conducted on medical, physical therapy, and music students revealed a prevalence of generalized joint hypermobility of approximately 13-27% [4; 8; 9], often accompanied by musculoskeletal complaints and psychological distress [4; 10]. While several studies have investigated the prevalence of generalized joint hypermobility, specific estimates for the prevalence of localized and peripheral joint hypermobility are limited [11]. When the affected individuals, such as dental care providers, require fine motor skills and manual dexterity to perform daily working activities, their functional performance may be impaired to varying degrees. Dental professionals rely on their stability, strength, and tactile senses to achieve acceptable clinical outcomes [8]. Unfortunately, individuals with peripheral joint hypermobility have been found to have lower proprioception [12; 13], which may result in inappropriate pressure, further hyperflexion of supporting muscles, and an increased risk of musculoskeletal symptoms and injuries [14; 15; 16; 17; 18; 19; 20]. Despite a significant negative impact on these individuals' daily working activities, limited data are available on peripheral joint hypermobility in dental professionals.