The clinical presentation is consistent with lateral epicondylitis, which is caused from pathologic changes at the origin of the extensor carpi radialis brevis (ECRB).
Physical exam findings consistent with lateral epicondylitis include tenderness over the lateral epicondyle at the origin of the ECRB, and pain that is reproduced with gripping, resisted long finger extension, resisted wrist extension while the elbow is fully extended, and maximum passive wrist flexion. This should be distinguished with the pain with resisted supination with the arm and wrist in extension characteristically seen with radial tunnel syndrome.
Nirschl et al looked at their surgical cohort of patients with lateral epidondylitis that were treated with surgery. They found the lesion that was consistently identified at surgery was immature fibroblastic and vascular infiltration of the origin of the extensor carpi radialis brevis (ECRB). There was an over-all improvement rate of per cent, and per cent of the patients returned to full activity including rigorous sports following surgical treatment.
Morris et al used indwelling EMG to look at muscle activity about the elbow during tennis strokes in nine professional and collegiate level players. They concluded the predominant activity of the wrist extensors in all strokes may be one explanation for predisposition to injury.