Instead of paying monthly insurance premiums, the company directly funds the claim payments as they come in. They outsource the work of adjudicating claims, negotiating with providers/facilities, cutting checks, setting approval criteria and first level appeals to another company, called a Third Party Administrator.
Now, who happens to have all the skills and expertise to do the job of a TPA? The big health insurers. These are giant companies with many lines of business. One of those lines is selling insurance to individuals and small businesses, another is selling administrative services to larger ones.
Note that even with a self-insured plan, there’s often insurance involved too: the company will buy a separate “stop-loss” policy that kicks in and starts paying after the employer has paid out a certain amount in total over a year. This protects them from the risk of covering a plan member with a particularly expensive condition.
Does this mean that the hospital self-insured and provided the surgery? As in why have Aetna involved at all then?