Trochanteric bursitis refers to inflammation of fluid-filled sacs located around the greater trochanter bone on the outside of the hip. It commonly causes deep aching pain on the outside of the hip and thigh that increases with activity and is worse when lying on the affected side. Risk factors include trauma, hip arthritis, back problems, obesity, and other conditions that alter gait or hip movement. Treatment focuses on rest, NSAIDs, physiotherapy, steroid injections, or occasionally surgery.