The effects of gender and pubertal status on generalized joint laxity in young athletes

Abstract

Our purpose was to examine the effects of pubertal status on generalized joint laxity in a population of male and female athletes. We hypothesized that females would show higher generalized joint laxity after the onset of puberty while males would not. This cross-sectional cohort study included 275 female and 143 male middle school and high school basketball and soccer athletes. Joint laxity was assessed using the Beighton and Horan Joint Mobility Index. BHJMI scores were averaged and female and male athletes were compared by pubertal stage. Females demonstrated increased joint laxity scores between pre-pubertal and post-pubertal groups (P=0.042), while males did not. Pre-pubertal male and female athletes were not different in cumulative joint laxity scores (female pre-puberty mean=2.00; male pre-pubertal mean=1.66). However, following the onset of puberty females (pubertal mean=2.96; post-pubertal mean=3.03) demonstrated a greater joint laxity score compared to males (pubertal mean=1.24; post-pubertal mean=1.30). Gender differences in BHJMI score was found at puberty and post-puberty (P<0.001). In contrast to males, females may have greater generalized joint laxity following the onset of puberty. Structural and physiological changes that occur during puberty such as alterations in passive joint restraints, may affect the type, severity and incidence of injuries in the maturing adolescent population.

Figure 1

Figure 1A) Fifth finger hyperextension test. Each subject’s forearm, wrist, and fingers were stabilized on a flat table. The tester passively extended the subjects fifth finger as far as possible without pain. Hyperextension of 90 degrees or greater resulted in a score of 1. Hyperextension less than 90 degrees resulted in a score of 0. Figure 1B) Elbow hyperextension test. Each subject’s shoulder was abducted to approximately 80 degrees, with the forearm supinated. The axis of the goniometer was placed over the lateral epicondyle of the humerus, with the distal end aligned with the radial styloid process and the proximal arm aligned along the lateral midline of the subject’s humerus. If elbow hyperextension was 10 degrees or greater a score of 1 was given. Hyperextension of less than 10 degrees resulted in a score of 0. Figure 1C) Thumb opposition test. Each subject flexed the wrist and pulled the thumb towards the forearm using the opposite hand. If the thumb could be abducted to touch the forearm the score of 1 was given. Inability to touch the forearm resulted in a score of zero. Figure 1D) Knee hyperextension test. Each subject was placed in a supine position with a box placed under both ankles. The axis of the goniometer was aligned with the lateral epicondyle of the femur. The distal arm was positioned with the lateral malleolus and the proximal arm was aligned with the greater trochanter. Hyperextension of the knee 10 degrees or greater resulted in a score of 1, anything less than 10 degrees resulted in a score of 0. Figure 1E) Palms to floor test. Each subject was instructed to keep both knees extended and attempt to touch the floor with the palms flat to the floor. The ability to touch both palms flat on the floor resulted in a score of 1. If the subject was unable to place both palms flat on the floor a score of 0 was given.

Figure 2

Gender and pubertal comparison (measured by the Pubertal Maturational Observational Scale) of the mean (± 1 SEM) Beighton and Horan Joint Mobility Index scores. *Females demonstrated higher generalized joint laxity scores compared to males at the pubertal and post-pubertal stages (P < 0.001).†Pubertal females demonstrated higher generalized joint laxity scores when compared to pre-pubertal females (P < 0.05).