Hi, thanks for writing to HCM. There are many causes for producing pain after a Primary Total Hip Replacement. * The pain could be originating from the prosthetic joint itself due to Loosening, Prosthetic failure, Impingement, Occult fracture of prosthetic components, Particulate debris induced synovitis etc * The pain may be arising from extra articular causes like Lumbar disc radiculopathy, trochanteric bursitis, periarticular tendinitis, Stress fracture of the pelvis etc. - Groin pain or deep buttock pain is associated with acetabular or capsular sources of pain. Groin pain can also be caused by iliopsoas tendinitis or proximal femoral problems. - Femoral component problems usually present with anterior thigh pain. - Posterior buttock and thigh pain, especially when associated with extension distal to the knee, is usually related to lumbar spine disease. - Pain over the greater trochanter implicates trochanteric bursitis, trochanteric nonunion, or painful trochanteric hardware. - If there has been a pain-free period after the THA, the late onset of pain suggests loosening or sepsis. - If pain increases in severity with increased walking or standing and is relieved by rest, it is usually associated with loosening, but loosening is rarely associated with rest pain alone. - Night pain, rest pain, or constant pain can be associated with sepsis/infection. So, a detailed clinical examination and appropriate investigations are needed to establish a possible cause for your pain. Hope this information is helpful. Good day