Bruce picked up the injury during a Northants T20 Championships defeat at Kislingbury Temperance last weekend and will now miss the rest of the tournament as well as a big area final in the ECB Club KO competition against Wanstead and Snaresbrook at Bretton Gate on June 19.
He is also a doubt for the Northants Premier Division top-of-the-table clash with Kislingbury on July 9.
"It’s a big blow as Lewis is obviously a key player for us,” Town skipper David Clarke admitted. “But we can’t do a lot about injuries and there is still plenty of talent available to us.
"It was such an innocuous incident as well. Lewis just fielded a ball off his own bowling. It wasn’t struck that hard at him, but he bowled one more over and then he couldn’t move his thumb so he went off to hospital to get it checked out and the news wasn’t good.”
Town continue in T20 Championship action this Saturday and they face two tough games in the new format as Oundle Town and Geddington are the visitors to Bretton Gate. Town tackle Oundle at 10.30am and the losers are straight back into action against Geddington (1.30pm) with the final match then scheduled for 4.30pm.
It’s been a competitive start to the evnt as only Kislingbury managed to record two wins and they had the advantage of playing on their own ground. Home knowledge certainly proved handy against Town, even before Bruce picked up his injury.
"It’s a lovely ground, but the dimensions are strange,” Clarke added. “We started our second game over an hour late because so much time had been wasted looking for the ball in the adjoining fields! Josh Smith was hitting the ball so far over the boundary he must have lost six balls on his own.
"It was noticable they played five seamers and no spinners which is handy to know for when we go back there later in the season. We used three spinners, but we could well still have won if we hadn’t missed an early chance to get their overseas pro out.”
The 10 Premier Division teams play six T20 matches apiece with the four leading sides going on to finals day on the last weekend of June.
Northants T20 Championships: Peterborough Town v Oundle, Peterborough Town v Geddington, Oundle v Geddington.
Lincs Premier Division: Bourne v Woodhall Spa, Lindum v Market Deeping, Spalding v Nettleham.
Cambs Division One: Ramsey v Foxton Granta, Wisbech v Old Leysians.
Cambs Division Two: Castor v St Ives & Warboys, Saffron Walden 2nds v Ufford Park.