Importance of Hip-Spine Syndrome in Hip Arthroplasty: Influence on the Outcome and Therapeutic Consequences.

Correct interaction between the spine, pelvis, and hip is an essential condition for successful progress after total hip replacement. Spinal pathologies, such as degeneration, fractures, and spinopelvic imbalance with and without lumbar fusions, are closely associated with an increased risk of impingement or even dislocation of the prosthesis. To significantly reduce this risk, various parameters are required to quantify the risk groups. Knowledge on the presence of stiffness of the spine (change in pelvic tilt between standing and sitting at < 10°) and sagittal spinal deformity (pelvic incidence-lumbar lordosis mismatch > 10° or 20°) is essential in identifying patients with corresponding risk. The individual risk profile can be assessed through a specific history and examination. Before total hip arthroplasty, a routine preoperative workup is recommended for high-risk patients: using information from standardised preoperative radiographs while sitting and standing (pelvis, anteroposterior view, lying and standing; spine and pelvis, lateral view, standing and sitting). Important changes can be made during the surgery. If the spine is stiff, attention should be paid to the position of the cup, with increased anteversion, sufficient offset, and larger head that is secure to dislocation - to reduce the risk of dislocation. In the case of a sagittal spinal deformity, the functional coronary pelvic level must be carefully controlled so that it is better to use double mobility cups. Digital systems, such as navigation and robotics, can optimise component positioning although, so far, there is little evidence that the complication rate decreased. Therefore, further studies are warranted.