EXHIBIT A JOINT FILING AGREEMENT
EXHIBIT A
The undersigned hereby agree that the statement on Schedule 13G with respect to the Common Stock of
Orthovita, Inc. dated as of February 17, 2009 is, and any amendments thereto (including amendments
on Schedule 13D) signed by each of the undersigned shall be, filed on behalf of each of us pursuant
to and in accordance with the previsions of Rule 13d-1(k) under the Securities Exchange Act of
1934, as amended.
| Date: February 17, 2009 | MAGNETAR FINANCIAL LLC |
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| By: Magnetar Capital Partners LP, its Sole Member |
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| By: | /s/ Xxxx X. Xxxxxxxx | |||
| Name: | Xxxx X. Xxxxxxxx | |||
| Title: | Manager of Supernova Management LLC, the General Partner of Magnetar Capital Partners LP | |||
| Date: February 17, 2009 | MAGNETAR CAPITAL PARTNERS LP |
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| By: | /s/ Xxxx X. Xxxxxxxx | |||
| Name: | Xxxx X. Xxxxxxxx | |||
| Title: | Manager of Supernova Management LLC, the General Partner of Magnetar Capital Partners LP | |||
| Date: February 17, 2009 | SUPERNOVA MANAGEMENT LLC |
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| By: | /s/ Xxxx X. Xxxxxxxx | |||
| Name: | Xxxx X. Xxxxxxxx | |||
| Title: | Manager | |||
| Date: February 17, 2009 | /s/ Xxxx X. Xxxxxxxx | |||
| Xxxx X. Xxxxxxxx | ||||
