The tribunal heard that Prof Richardson had used a piece of equipment used to blow air into the knee joint, which he had modified specifically for the operation.
"It's a blow to injure the same knee, " admitted Tigers boss Richard Cockerill.
But the Hawkeyes suffered a major blow when heavyweight Bobby Telford hurt his knee during an easy win over Wisconsin's Connor Medbery.
Portugal suffered a further blow when Moutinho hobbled off with a knee injury to be replaced by Raul Meireles, but they showed more promise just before halftime.
Arsenal have suffered another injury blow with midfielder Alex Song ruled out with a knee problem, joining captain Cesc Fabregas, France defender William Gallas and Russia forward Andrei Arshavin on the sidelines.
Armagh then suffered a blow when John Toal had to be stretchered off with a knee injury.
BBC: SPORT | Northern Ireland | Gaelic Games | Armagh fight back to earn replay
Hughes' plans for the new season suffered a blow on Tuesday when Darius Vassell was ruled out for 10 weeks with a knee injury.
Saints had the bulk of possession but the Wigan defence held firm and the home side were dealt a blow when captain Keiron Cunningham was forced off in the first half with a knee injury.
De Marigny opened the scoring with a third-minute penalty, before the Dragons suffered a blow as captain full-back Kevin Morgan left the field 10 minutes later with a knee injury.
The loss of Lawes, who was England's player of the series in the autumn, is a huge blow, although Johnson is optimistic the 21-year-old's recovery from knee ligament damage might be quicker than the three months originally expected.
The home side had received an attacking blow prior to kick-off when talismanic 22-goal striker Fernando Torres was ruled out with a knee injury.
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