Perform this exercise with your prosthetic off.
Sit on the floor with your legs bent, feet flat on the floor and upper back against a bench.
Place a resistance band around your knees.
Push your knees apart to create tension on the band and hold this tension throughout the movement.
Press your feet against the floor and explosively lift your hips up until you have a straight line from knees to shoulders and your hips are level.
Lower your hips back towards the floor.