Dr. Gelber was part of a symposium on knee ligament injuries in professional soccer players at a prestigious conference held in Porto, Portugal, under the patronage of FIFA, UEFA, ISAKOS and ESSKA. The Meeting was organized by Dr. Joao Espregueira. At that symposium, Dr. Gelber discussed the serious multiligament knee injuries that occur in elite football players. At the symposium, other prestigious world specialists in complex knee injuries of the likes of Drs. Fu, Seil, Leyes, Neyret, Cohen, Karlsson and Karahan also have participated. This conference demonstrates his position as a  world-leader on knee injuries.