Do Spine Fusion Patients With Hip Arthroplasty Risk Dislocation?

A new study of 42,300 patients explores the question of whether patients undergoing lumbar spinal fusion (LSF) before total hip arthroplasty (THA)—versus after—have an increased risk of dislocation and revision.

The study, “Does Timing of Primary Total Hip Arthroplasty Prior to or After Lumbar Spine Fusion Have an Effect on Dislocation and Revision Rates?” appears in the January 14, 2019 edition of The Journal of Arthroplasty.

Study co-author Arthur Malkani, M.D. of the University of Louisville Adult Reconstruction Program, explained to OTW the rationale for this large study: “There has been a significant increase in the number of patients undergoing primary THA with a history of prior lumbar spine fusion. Lumbar spine fusion is an independent risk factor for dislocation leading to increased risk of revision.”

“The prevalence of hip dislocation following primary THA in patients with prior lumbar spine fusion in the Medicare population is 7.4%. Lumbar spine fusion alters spino-pelvic anatomy leading to loss of the normal pelvic parameters during standing and sitting which could lead to hip impingement and instability.”

In the study, 28,668 patients underwent lumbar spine fusion and then total hip arthroplasty sometime later and 13, 632 had the reverse—total hip arthroplasty followed by lumbar spine fusion sometime after.

Dr. Malkani told OTW, “In our practice we are seeing more patients presenting with both lumbar spine disease and primary hip osteoarthritis. The purpose of this large database study was to determine if hip instability could be decreased if the hip replacement was done first prior to the lumbar fusion in patients with both lumbar spine disease and hip arthritis.”

“The results from this study suggest a significant advantage for patients to undergo THA first if concomitant lumbar spine and hip pathology are likely to require both lumbar spine fusion and THA.”

“There was a 46% increased risk of dislocation in patients with prior LSF compared to the group that had a THA done first followed by a LSF within 1 year, 60% increased risk of dislocation compared to THA first then LSF at 2 years and 106% increased risk compared to THA first and delayed LSF by 5 years. The greater the interval between index THA and proceeding LSF, the lower the risk of dislocation and THA revision.”

“Instability continues to be the leading cause of failure following primary THA leading to revision surgery. We need to identify high risk patients for instability prior to the primary THA. We need to start asking patients if they have any history of lumbar spine disease during the initial visit prior to the THA. In those patients with concomitant lumbar spine disease and hip osteoarthritis, the arthroplasty and spine surgeons need to collaborate to determine if the hip arthroplasty can be approached first with a delay in spine surgery.”

“Additional work is required to determine the ideal functional acetabular cup position in patients with a rigid lumbosacral-pelvic biomechanical relationship and altered pelvic parameters. Surgeons should look at multiple factors in patients undergoing THA with a history of prior lumbar spine fusion to minimize dislocation such as preoperative assessment of pelvic parameters, ideal surgical approach, maximizing head size, restoring offset, satisfactory implant alignment, and an intraoperative assessment of stability.”