He did not participate Tuesday when the Dolphins held an OTA (offseason training activity) that was open to the media.
The former sixth-round pick suffered a broken left foot (Lisfranc fracture) during Miami's opening game last season and was placed on injured reserve.
After Thomas was injured last season, backup G Ikechuku Ndukwe started the rest of the season in his place. Backup OL Andy Alleman, who was claimed off of waivers from the New Orleans Saints last season, started the final four games at left guard in place of injured starter Justin Smiley.
Thomas' agent, Ed Wasielewski, did not respond to phone messages seeking comment.