SAN DIEGO -- Pitcher Mark Prior was admitted to Scripps Clinic on Wednesday to have season-ending surgery to repair a torn anterior capsule in his right shoulder.

If it were only that simple.

As it turns out, the doctors who performed the surgery, team physicians Heinz Hoenecke and Jan Fronek, discovered something altogether rare.

The capsule in Prior's right shoulder had torn away from the humerus bone, an injury neither Hoenecke nor Fronek had ever heard of another baseball player having it before.

HAGL, as it's called, describes a humeral avulsion of the glenohumeral ligaments. The injury, according to Fronek, is most often associated with a "traumatic events, usually from a fall."

Prior was 13 months removed from arthroscopic surgery on the same shoulder, though Hoenecke said that surgery had done its job and the HAGL tear was unrelated.

Prior, who signed a one-year, $1 million deal in December, will be a free agent after the season. San Diego general manager Kevin Towers said he was amendable to talking to Prior's agent, John Boggs, possibly about a Minor League deal after the season.

Since HAGL tears are rare, there's no timetable for when Prior could resume throwing though Fronek said he could "optimistically" be throwing again by next spring.