Short stem total hip arthroplasty: Potential explanations for persistent post-surgical thigh pain.

Short stem uncemented femoral implants were developed with the aim of preserving proximal bone stock for future revisions, improving biomechanical reconstruction, aiding insertion through smaller incisions and potentially decreasing or limiting the incidence of thigh pain. Despite all the advantages of short stem designs, it remains unclear whether they are able to limit post-surgical thigh pain. In patients with short stem hip arthroplasty and persistent thigh pain, it is of the utmost importance to understand the potential etiologies of this chronic pain for selecting the appropriate treatment strategy. Therefore, this manuscript explores the hypothetical etiologies of persistent thigh pain in short stem total hip arthroplasty, including both peripheral factors (structural or biomechanical causes) and central factors (involvement of the central nervous system). First, intrinsic causes (e.g. aseptic femoral loosening and prosthetic joint infection) and extrinsic sources (e.g. muscle pathology or spinal pathology) of persistent thigh pain related to hip arthroplasty are explained. In addition, other specific peripheral causes for thigh pain related to the short stem prosthetic reconstruction (e.g. stem malalignment and micro-motion) are unraveled. Second, the etiology of persistent thigh pain after short stem hip arthroplasty is interpreted in a broader concept than the biomechanical approach where peripheral structural injury is believed to be the sole driver of persistent thigh pain. Over the past decades evidence has emerged of the involvement of sensitization of central nervous system nociceptive pathways (i.e. central sensitization) in several chronic pain disorders. In this manuscript it is explained that there might be a relevant role for altered central nociceptive processing in patients with persistent pain after joint arthroplasty or revision surgery. Recognition of a potential role for centrally-mediated changes in pain processing in total hip replacement surgery has important implications for treatment. Comprehensive treatment addressing peripheral factors as well as neurophysiological changes occurring in the nervous system may help to improve outcomes in patients with short stem hip arthroplasty and chronic thigh pain. Working within a biopsychosocial approach in orthopaedic surgery, specifically in relation to total hip arthroplasty, could be very important and may lead to more satisfaction. Further research is warranted.