Will Lower Back Pain Resolve after THA?
Editor’s Note: Research papers intended for presentation at the canceled annual meeting of the American Academy of Orthopaedic Surgeons are now available online at the AAOS Virtual Education Experience. We’ll be highlighting a few of the more interesting papers throughout the summer.
It’s not uncommon for patients who need a total hip arthroplasty (THA) to also complain of lower back pain, which is often related to the change in body mechanics caused by osteoarthritis in the hip. In most patients – but not all – this back pain resolves after THA.
Is there a way for surgeons to predict which THA patients would be more or less likely to experience resolution of back pain after hip surgery?
That was the question researchers from Hospital for Special Surgery and NYU Langone Health sought to answer in their recent study investigating whether the use of spinopelvic parameters – specifically, pelvic incidence and sacral slope change from standing to sitting – could predict the likelihood of lower back pain resolving after THA.
In 500 consecutive THA patients, 204 had documented lower back pain in addition to osteoarthritis of the hip. The researchers collected demographic data and Oswestry Disability Index and Visual Analog Scale scores preoperatively and at 6 weeks and 1 year after surgery. They also obtained biplanar standing and sitting radiographs before surgery to calculate pelvic incidence and sacral slope change.
Lower back pain resolved in 82% of patients at a minimum of 1 year after THA. The sacral slope change from standing to sitting was more than 10° in patients whose back pain resolved, compared with less than 10° in those who did not experience improved back pain. Pelvic incidence did not predict whether back pain would resolve.
“There is definitely a group of patients whose back pain predictably goes away after hip replacement surgery, and those are people who have flexible spines,” said lead study author Jonathan M. Vigdorchik, MD, who specializes in hip and knee arthroplasty at HSS. “When we took standing and sitting lateral [radiographs], and we saw specific changes in patients with flexible spines, those were the patients whose back pain very reliably went away. Their back pain was exacerbated or even caused by their hip arthritis.
“Then there were certain patients who had a stiff, degenerative spine whose back pain did not go away, and that is because their spine arthritis had progressed to the point beyond which the hip was causing an effect.”
The findings should help clinicians counsel patients. “If clinicians get these [radiographs] and they see the certain things we saw, they can counsel their patients that their back pain will reliably go away after their hip replacement, and that it is safe to do the hip replacement first as opposed to going through spine surgery first for the back pain Dr. Vigdorchik said.
Vigdorchik JM, Shafi K, Buckland AJ, Carroll KM, Jerabek SA. Does Low Back Pain Improve Following Total Hip Arthroplasty? Paper 529. AAOS Virtual Education Experience.