Newton-based Senior Housing Properties Trust has entered an agreement to sell two Massachusetts rehabilitation hospitals to a joint venture comprised of affiliates of The Sanders Trust LLC of Alabama and Harrison Street Real Estate Capital LLC of Illinois for $90 million.

The two hospitals to be sold are New England Rehabilitation Hospital in Woburn and Braintree Rehabilitation Hospital. These hospitals were acquired by Senior Housing Properties Trust in 2002. Their real estate assets are currently leased to Five Star Quality Care Inc. under a combination lease that also includes 51 senior living properties.

In connection with the transactions, Five Star Quality Care Inc. has agreed to terminate its lease of the hospitals and transfer its operating rights and obligations, subject to regulatory approvals, to entities affiliated with Reliant Hospital Partners LLC, a private company in Texas, which will operate the hospitals when the sale is completed.

The sale of these hospitals is not subject to any financing condition, but the transaction is subject to various health regulatory approvals and other closing conditions. Senior Housing Properties Trust expects the sale to be completed by mid-year 2014.