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Joint laxity may be an advantage in sports such as gymnastics but a disadvantage in physical contact sports. Greater laxity has been shown to increase the risk of knee injury in professional footballers but not in high school players. A study in New Zealand has related ligamentous laxity to injury in amateur, first division club, rugby players.
Fifty one players were examined using a modified Beighton-Horan nine point scale (0 or 1 point for each of: passive opposition of thumb to flexor aspect of forearm (two sides), passive hyperextension of little finger at metacarpal phalangeal joint beyond 90° (two sides), elbow hyperextension to 15° or greater (2 sides), knee hyperextension (two sides), and palms flat on floor with knees extended). A stiff limb joint due to previous injury was recorded as lax if the uninjured joint was lax. Three categories of overall laxity were used: tight (score 0–3), hypermobile (4–6), and excessively hypermobile (7–9). Thirty nine players were classified as tight, eight as hypermobile, and four as excessively hypermobile. Strength testing in hamstrings and quadriceps was performed in nine players in the tight group and nine others.
The mean laxity score was 2.0. Over the rugby season there were 31 shoulder, hip, knee, ankle, wrist, or hand joint injuries in 23 players. Injury rates were similar in the three defined laxity groups but when the two hypermobile groups were combined (scores 4–9) they had a significantly higher injury rate than the tight group (116.7 injuries/1000 playing hours v 43.6/1000 playing hours). There was a non-significant trend towards greater strength in quadriceps and hamstrings in the tight group. Among the hypermobile group greater strength was not associated with fewer injuries.
Ligamentous laxity may increase the risk of injury in first division club, rugby players. (The effect of playing position was not assessed in this study.) The injury rate among these hypermobile amateur players was similar to that previously reported in professional rugby union players (120/1000 playing hours). The authors of this paper suggest that young athletes who are hypermobile might be advised to take up sports in which hypermobility could be an advantage.