Joint hypermobility is a clinical condition characterized by joints having a range of motion beyond their normal limits. Hormonal factors are thought to play a role in the development of joint hypermobility. One of the most significant indicators of prenatal androgen exposure is considered the ratio of the lengths of the second and fourth fingers (2D:4D). The 2D:4D digit ratio refers to the ratio of the lengths of the second finger (2D; index digit ) and the fourth finger (4D; ring digit). Evidence suggests that the 2D:4D ratio is developmentally stable and stabilizes from the second trimester of pregnancy onward. To our knowledge, intrauterine androgen exposure (2D:4D) has not been examined in populations with joint hypermobility. Therefore, the planned study aimed to examine the 2D:4D digit ratio in young adults with joint hypermobility and compare it with that of individuals without joint hypermobility.
Estrogen affects collagen metabolism and connective tissue structure, which can lead to increased ligament laxity at high levels. Increased estrogen and progesterone during pregnancy cause significant loosening of connective tissue, which can contribute to temporary joint hypermobility. Physiological conditions such as pregnancy and menopause can cause hormonal changes, increasing the risk of joint hypermobility through fluid retention and connective tissue changes. Testosterone, on the other hand, is a hormone that strengthens muscle mass and tendon structure, while at low levels it can cause connective tissue to remain looser. Therefore, the combination of high estrogen and relatively low testosterone, particularly in women of reproductive age, may contribute to the higher prevalence of hypermobility. Therefore, the aim of the planned study was to examine the 2D:4D digit ratio in young adults with joint hypermobility and compare this ratio with individuals without joint hypermobility.
Study Type
OBSERVATIONAL
Enrollment
180
The Beighton Scoring System is widely used to distinguish individuals with generalized joint hypermobility from those without. The Beighton Scoring System consists of: • Passive dorsiflexion of the fifth metacarpophalangeal joint • Passive hyperextension of the elbow • Passive hyperextension of the knee joint • Passive placement of the thumb on the flexor side of the forearm • Forward flexion of the trunk In adults up to 50 years of age, a score of ≥5 out of 9 indicates joint hypermobility, while in adults over 50, a score of ≥4 out of 9 is considered positive for joint hypermobility.
The lengths of the second (2D) and fourth (4D) digits will be measured separately on both hands. Measurements will be taken with the participants' hands placed on a flat surface with the palms facing upward. Digit length will be defined as the distance from the midpoint of the proximal crease at the base of the finger to the distal tip of the finger. A digital caliper with a precision of 0.01 mm will be used, and two separate measurements will be obtained for each finger, with the mean value recorded. Based on these measurements, the 2D:4D digit ratio will be calculated for each hand by dividing the length of the second digit by that of the fourth digit. To enhance reliability, assessments will be performed independently by two different researchers, and inter-rater agreement will be evaluated.
Nigde Omer Halisdemir University
Niğde, Turkey (Türkiye)
Beighton Scoring System
Individuals will be assessed for joint hypermobility (Beighton Scoring System) by a physical therapist. The Beighton Scoring System is widely used to distinguish individuals with generalized joint hypermobility from those without. The Beighton Scoring System consists of: * Passive dorsiflexion of the fifth metacarpophalangeal joint * Passive hyperextension of the elbow * Passive hyperextension of the knee joint * Passive placement of the thumb on the flexor side of the forearm * Forward flexion of the trunk In adults up to 50 years of age, a score of ≥5 out of 9 indicates joint hypermobility, while in adults over 50, a score of ≥4 out of 9 is considered positive for joint hypermobility.
Time frame: 1 month
2D:4D Digit Ratio
The lengths of the second (2D) and fourth (4D) digits will be measured separately on both hands. Measurements will be taken with the participants' hands placed on a flat surface with the palms facing upward. Digit length will be defined as the distance from the midpoint of the proximal crease at the base of the finger to the distal tip of the finger. A digital caliper with a precision of 0.01 mm will be used, and two separate measurements will be obtained for each finger, with the mean value recorded. Based on these measurements, the 2D:4D digit ratio will be calculated for each hand by dividing the length of the second digit by that of the fourth digit. To enhance reliability, assessments will be performed independently by two different researchers, and inter-rater agreement will be evaluated.
Time frame: 1 month
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