In another controversy involving all-metal hips, an influential group has found that there is insufficient evidence to show that an alternative technique known as hip resurfacing is as safe and effective as a traditional replacement. The group, the California Technology Assessment Forum, reversed a position it took just last year, citing recent findings by orthopedic registries overseas that some resurfacing devices are failing prematurely and health concerns about metallic debris released as the devices wear. The findings of the forum, which is financed by the Blue Shield of California Foundation, are not binding. Still, the group's report is likely to be disputed by advocates of resurfacing and patients who say they have benefited from the procedure. Hip resurfacing differs from a traditional joint replacement in that more of a patient's thigh bone is preserved than in a standard operation. Doing so, device makers and orthopedic experts say, allows patients to remain active and preserves bone for future procedures.