Goldman Sachs has been hired by Centerpulse, the Swiss orthopaedics company at the centre of a takeover battle, to provide additional advice alongside UBS Warburg and Lehman Brothers.

Goldman, which has worked with the company before, was hired on Wednesday as a strategic adviser. Centerpulse in March agreed to be bought for Sfr3.3bn (€2.16bn) by Smith & Nephew in the UK, but last week Zimmer, a US rival, upped the pressure when it said it would offer Sfr4.16bn for the Swiss company. According to a source close to the company, should Zimmer proceed with its offer without the agreement of the Centerpulse management it would be the first hostile deal in Switzerland since new takeover laws were introduced six years ago.