Mike Watt THE SECONDMAN’S MIDDLE STAND (Columbia/RED Ink)

As part of his legendary punk trio the Minutemen, his well-respected alt-rock band fIREHOSE, and on his own, Mike Watt has transformed the mundane into compelling source material for his bass-anchored prog-grunge, which always manages to be complex enough for gearheads without tilting full-on into wonky Guitar Center territory. On 1997’s Contemplating the Engine Room (Columbia), for example, he made the longshoreman’s life in his native San Pedro, California, sound riveting.

So Watt almost had it easy for The Secondman’s Middle Stand, a "punk-rock opera" about his struggle with surgery to remove an internal abscess from his perineum. "It was like a bullet hole from the inside," Watt effuses colorfully on his Web site, "and more than a quart of pus dumped out." With that thematic intensity built into the nine songs here — three each in three different movements — Watt and his two band mates concentrate on riding their bass-organ-drums grooves as hard as possible without sacrificing their peculiar tenderness. In "Pluckin’, Pedalin’ and Paddlin’," from the section about Watt’s recovery, former That Dog member Petra Haden adds breezy harmonies; in "Pissbags and Tubing," Watt makes a reflection on catheters feel downright anthemic.

(Mike Watt appears this Wednesday, October 27, at T.T. the Bear’s Place, 10 Brookline Street in Central Square; call 617-492-BEAR.)