Effects of habitual knuckle cracking on metacarpal cartilage thickness and grip strength

Joint cracking involves a manipulation of the finger joints resulting in an audible crack. This study aimed to determine whether habitual knuckle cracking (KC) leads to an alteration in grip strength and metacarpal head (MH) cartilage thickness. Thirty-five habitual knuckle crackers (cracking their joints ≥5 times/day) (20 M, 15 F, aged 19–27 years) and 35 age-, gender-, and body mass index-matched non-crackers were enrolled in the study. MH cartilage thickness was measured with ultrasound and grip strength was measured with an analog Jamar hand dynamometer. Grip strength was similar between groups (P > 0.05). Habitual knuckle crackers had thicker MH cartilage in the dominant and non-dominant hands than those of the controls (P = 0.038 and P = 0.005, respectively). There was no correlation between MH cartilage thickness and grip strength in both groups (P > 0.05). While habitual KC does not affect handgrip strength, it appears to be associated with increased MH cartilage thickness.