What Does Enostosis Within The Capitellum Mean?

I was diagnosed with tennis elbow in August of this year. I had a cortisone injection in October with no relief. I had an MRI on January 22, 2015. The MRI results state: Enostosis within the capitellum, small elbow join effusion and intrasubstance tearing of the common extensor tendon at its humeral attachment. I have not seen my Dr to have this explained but can you please tell me what this means.