SURF RIDING is largely confined to the beaches of California and Hawaii, but is now gaining in popularity on the east coast as well. The physical hazards of this very exhilarating sport are those expected from the use of a heavy fiber glass surfboard in a pounding surf. These hazards include a large assortment of cuts and bruises, and an occasional fatality produced by a rapidly moving board striking the head.
In addition, regular devotees of the sport acquire surfers' knots, soft-tissue swellings on the dorsum of the foot and just below the knee.1 Surfers' knots are produced at these points by kneeling for long periods of time on a floating surfboard while waiting for a wave. When the surfer kneels on the board, the feet are tucked under the buttocks with most of the body's weight brought to bear on the dorsum of the foot.2
Gelfand DW. Surfer's KnotsAssociated Bone Changes and Medical Problems. JAMA. 1966;197(2):149–150. doi:10.1001/jama.1966.03110020137049