Acetabular fractures affect the socket of the hip bone, and are generally sustained after violent trauma, such as road traffic accidents.
But a group of doctors in Ireland, writing in the journal BMJ Case Reports, describe these injuries in three young rugby players and say "we have not previously encountered these injuries in a juvenile sporting population"
The injuries were sustained while playing rugby union, two during seasonal match play and one during a training drill. Previously, the doctors reported two acetabular fractures in two other young rugby players, aged 16 and 24 years.
All four injuries occurred during the tackle phase of play, and occurred as a result of pressure exerted through a flexed hip with the knee on the ground. This position can be encountered during a two man tackle, as one tackler hits low and the other hits high.
Three of these fractures occurred along with with hip dislocations.
All three boys, as reported in this latest case, recovered following surgery and rehabilitation, without any major implications. However, these injuries can have a potentially devastating impact on growth, sporting participation and lifestyle of young players.
"In order to prevent the potentially devastating consequences of these injuries it may be necessary to implement rule changes or size restrictions in the juvenile game," say the doctors.
Players may be of the same age, but can be different in size and stage of development. This is associated with an increased injury risk, they explain, adding to the problems linked with excessive force in an immature skeleton.
"An evaluation of the rules at the breakdown and an emphasis on proper tackling could aid injury prevention," they explain.