The hip spine relationship — what we know and what we don’t: a narrative review

Background and Objective: The hip-spine syndrome was first described in 1983. The premise of the report was that the hip and spine are closely related and patients can easily have overlapping conditions and misdiagnoses. Since that time, there has been considerable advancement in our understanding of spinopelvic parameters and how degenerative disc disease can affect the pelvis and subsequently the acetabulum. Our objective is to provide an updated review on the relationship between hip and spine degeneration, how we define the relationship, and what steps should be taken when planning surgical intervention for these patients. Methods: A literature review was conducted via the PubMed database. Articles were screened based on their relevancy, recency, and quality of analysis. Search items included the following MeSH terms: “lumbar spine” with free text items: “hip, arthroplasty, parameters, spinopelvic, sagittal alignment, fusion, total hip arthroplasty, hip-spine syndrome, surgical complications, and dislocation”. Key Content and Findings: Novel spinopelvic parameters such as the combined sagittal index (CSI) may be useful in predicting complications in patients undergoing total hip arthroplasty. A reasonable approach may be to perform hip arthroplasty prior to a multilevel spinal fusion, especially when the fusion includes the pelvis. However, for patients with radiculopathy requiring a simpler one-or two-level spinal fusion, the spine may be safely addressed first to relieve the patient of radiculopathy prior to proceeding with a hip arthroplasty. Conclusions: New interpretations and applications of these parameters may decrease risk, prevent complications, and improve outcomes for patients who experience these associated, and often concurrent, pathologies.