It is hypothesized that autologous blood injections may trigger the inflammatory cascade and initiate healing of degenerative tissue via mediators in the blood or localized trauma from the injection itself. One case series, including 29 patients who had failed other conservative modalities, reported a 79 percent improvement in pain scores over an average of months; some patients required multiple injections. 27 However, clinical trials that include a comparison group receiving placebo injections are lacking, and until these trials are completed, autologous blood injections cannot be recommended.
In tennis players, about % have reported current or previous problems with their elbow. Less than one quarter (24%) of these athletes under the age of 50 reported that the tennis elbow symptoms were "severe" and "disabling," while 42% were over the age of 50. More women (36%) than men (24%) considered their symptoms severe and disabling. Tennis elbow is more prevalent in individuals over 40, where there is about a four-fold increase among men and two-fold increase among women. Tennis elbow equally affects both sexes and, although men have a marginally higher overall prevalence rate as compared to women, this is not consistent within each age group, nor is it a statistically significant difference. 
The lateral epicondyle of the humerus is a small, tuberculated eminence, curved a little forward, and giving attachment to the radial collateral ligament of the elbow joint, and to a tendon common to the origin of the supinator and some of the extensor muscles. Specifically, these extensor muscles include the anconeus muscle , the supinator , extensor carpi radialis brevis , extensor digitorum , extensor digiti minimi , and extensor carpi ulnaris .  In birds , where the arm is somewhat rotated compared to other tetrapods , it is termed dorsal epicondyle of the humerus . In comparative anatomy, the term ectepicondyle is sometimes used.