PORT-AU-PRINCE, Haiti — The big diagnostic mystery of the newly arrived aid group’s first surgical case was the lamp.

A standing parabolic surgical light, it wouldn’t turn on. Neither new bulb, alternative cord nor different plug would make it work. So the surgical team operated with camping headlamps instead.

The patient’s problem was, in surgical terms, more straightforward: compartment syndrome of the right lower leg.

Emmanuel Etan, 21, had been trapped under a collapsed cement-block wall for two days, rescued and then treated with a procedure that opened the calf in order to relieve the pressure caused by swelling.

It was the right procedure but not sufficiently aggressive. By Wednesday, Etan’s leg was dangerously reswollen, the pressure inside the calf high enough to impair blood flow. Unrelieved, it would kill the tissue, which would become infected and require amputation — if it didn’t kill the young man first.

“I wouldn’t call it easy. But it was less complicated than some of the cases we have waiting,” said Waseem Saeed, a 46-year-old British plastic surgeon who did the new operation in the semi-dark in a 30-by-24-foot tent erected on the undamaged asphalt courts of a tennis club. There was no X-ray and no supplemental oxygen. The temperature was in the 90s. A window at one end and a door at the other provided ventilation.

It took Saeed two hours to explore the wound, clean and trim it, and complete two muscle-opening cuts (called fasciotomies). The young man’s deep hand wound, with two broken bones, was also cleansed and bandaged.

Then, Etan was wheeled off to the recovery room — the space behind the baseline on the court, next to the generator.

Saeed did three surgical cases on Thursday, his first full day operating, and his colleagues did two procedures outside the OR tent, including the realignment of a broken ankle. The clinic doctors saw 60 patients, double the day before.

It is operations such as these that are starting to be done in large numbers in Haiti, more than a week after the devastating earthquake. They are operations designed to revise hasty or incomplete earlier procedures, or ones done perfectly well that have simply taken a downhill course to infection and other complications.

The organization Partners in Health, whose two decades of work in Haiti Tracy Kidder chronicled in his 2004 book “Mountains Beyond Mountains,” has 12 operating rooms working in the university hospital here. The Navy floating hospital Comfort, with substantial surgical capacity, began taking patients on board Tuesday night. Many other relief agencies and national governments also have surgeons operating here.