Doctors in Swansea say they have transformed the way they carry out complex operations by using a new nerve block instead of general anaesthetic.
By targeting injections using ultrasound, patients who would have needed days in hospital can have surgery and be sent home within hours.
The pain relief technique is currently being used for hand and arm operations.
The local health board said the process saves money and creates less risk for patients.
The nerve block - a regional anaesthesia - has been developed in the day surgical unit at Singleton Hospital.
It is different to a local anaesthetic in that it works on the nerves affecting the whole arm, rather than a part of it.
It is also stronger, and the effects continue after the operation, giving additional pain relief for about 12 hours.
As a result, the patient remains fully conscious throughout surgery and goes home within half an hour, instead of being an inpatient for two to three days if they had been given a general anaesthetic.
From arriving at the unit to going home, the total time a patient is in hospital is around two-and-a-half hours.
Abertawe Bro Morgannwg University Health Board said: "As patients don't need a general anaesthetic, they don't get side effects like drowsiness or nausea, and they don't face any of the risks of a general anaesthetic.
"Regional anaesthesia can also be used for patients who are not well enough to risk a general anaesthetic."
It added that the new surgery showed savings of between £350 and £650 per session, even before taking into account the money saved by a patient not being in a hospital bed for several days.
BBC Wales' health correspondent Hywel Griffith said that although the technique is only being used for hand and arm surgery at the moment, it could potentially be adapted for other orthopaedic surgery in the future.
Dr Christian Egeler, a consultant anaesthetist at the unit, said the technique was good for patients.
"Patients are awake which reduces the side effects from general anaesthetic and, this being a day surgery setting, it means they're ready to go home very shortly after. They have a cup of tea and go," he added.