Finding an opponentÃ¢ÂÂs weakness is all part and parcel of the game.So when it came to light that Ricky Kaka was playing through the pain barrier of a knee problem it was odds-on the Brazilian would soon become the target of Serie AÃ¢ÂÂs masters of the dark arts of the late challenge.In fact, it was all of two minutes before the World Player of the Year was left writhing on the ground during SundayÃ¢ÂÂs league game against Palermo. A minute later and he was again picking himself up off the San Siro turf.Two shaven-headed midfield assassins, in the shape of Roberto Guana and Giulio Migliaccio, had taken turns at aiming kicks at the fragile knee and in doing so could have boosted ArsenalÃ¢ÂÂs hopes of reaching the quarter-finals of the Champions League.Kaka limped off at half-time, not to return but to lament that referees were not giving him enough protection from the hatchet merchants. It certainly seems to be open season on the God-fearing south American and the clubÃ¢ÂÂs official site even published a photo of one of the fouls framed inside a telescopic gun-sight, along with the catchy little caption: Ã¢ÂÂHunting for KakaÃ¢ÂÂ. Milan hope to have their star performer back for the arrival of the Gunners next week but as the head of the MilanLab, Daniele Tognaccini explained: Ã¢ÂÂAny normal person taking these constant knocks would not be able to get out of bed never mind walk Ã¢ÂÂ¦Ã¢ÂÂ so the chances of recovery would seem to hang in the balance.Kaka isnÃ¢ÂÂt the only player to have been brought to his knees of late. Adrian Mutu is out with strained ligaments for at least a month and will definitely miss the first leg of the UEFA Cup tie with Everton.Zlatan Ibrahimovic tried to outdo the other two by claiming he had a hole in his knee tendon which suggests he should be hobbling off to the nearest emergency room rather than trying to strut around a football pitch.Just as the public in England got to know the workings and failings of the metatarsal bone ahead of the 2006 World Cup finals so Italians are now experts on ACLs (anterior cruciate ligaments for those who arenÃ¢ÂÂt). Gazzetta dello Sport has been sounding more like a medical journal in recent weeks and produced a number of handy diagrams on where these troublesome ligaments and tendons actually are inside the maze that is the knee joint.Ronaldo kicked the whole thing off so to speak but there has also been Inter defensive pair Ivan Cordoba and Walter Samuel along with midfielder Olivier Dacourt and Empoli and Italy Under-21 striker Nicola Pozzi all succumbing to the curse of the ACL or some equally season-ending equivalent.There has been a lot of head-scratching, and not some other appendage for a change, up and down the country to remember the last time there had been so many popped knees and ruptured ligaments. The general consensus is that referees need to clamp down on the aggressors so the flair players arenÃ¢ÂÂt kicked out the game completely. Another school of thought maintains thatÃ¢ÂÂs the way of the world in macho Serie A and the likes of Kaka should quit their whinging. Wherever you land on the issue, at least itÃ¢ÂÂs a good time to be an orthopaedic surgeon.