Researchers from NYU Langone Health have developed an assessment tool that they suggest could help identify which patients undergoing total hip replacement may be at a higher risk for implant dislocation following the surgery.

The study titled “A New Risk-Assessment Score and Treatment Algorithm for Patients at High Risk of Dislocation following Total Hip Arthroplasty,” received the Best Poster in the Adult Reconstruction Hip classification at the American Academy of Orthopaedic Surgeons (AAOS) 2018 Annual Meeting in New Orleans.

Research presented at last year’s AAOS Annual Meeting showed that spinal deformity was a significant risk factor for dislocation and subsequent revision surgery. The researchers reported at the time how the lumbar spine, or lower back, moves during posture changes like transitioning from sitting to standing, creating alterations in so-called spinopelvic relationship,” which changes position of the hip socket and may cause an implant to dislocate in a person with spinal deformity.

This led researchers to further develop a risk prediction tool to better identify which patients undergoing a hip replacement may be at higher risk for dislocation, and then implement a treatment algorithm to help reduce that risk, notes a media release from NYU Langone Health.

“Dislocation is a common reason for a total hip replacement to fail, and when it happens, sufferers can experience significant pain and require another surgery to fix the problem,” explains lead study author Jonathan Vigdorchik, MD, an assistant professor of orthopedic surgery at NYU School of Medicine and associate fellowship director of the Division of Adult Reconstructive Surgery at NYU Langone Orthopedic Hospital, in the release.

“Orthopedic surgeons need to be more aware of this problem and think about the risk of dislocation prior to performing a hip replacement instead of just dealing with the complications after the surgery. We need to be proactive in our approach,” he adds.

In the study, researchers reviewed data on 1,082 total hip replacements performed using computer navigation between January 2014 and December 2015, during which period no dual-mobility implants were used. The overall implant dislocation rate among this cohort was found to be 1.8%. Of this group, 320 patients had lumbar spinal degeneration or deformity as diagnosed by imaging scans, and of them, 10 experienced dislocations, suggesting a dislocation rate of 3.1% for high-risk patients, or about three times higher than patients with normal lumbar spines.

Beginning in 2016, surgeons used the standardized risk prediction model and treatment algorithm developed at NYU Langone, which factored in data collected from preoperative imaging taken while the patient was sitting and standing, and other measures that might affect risk for dislocation, including presence of degenerative spinal pathology, spinal deformity, or a prior lumbar fusion.

Using the risk assessment tool, the researchers identified 192 of 1,009 patients as high risk for a dislocation after surgery. All 192 patients underwent a total hip replacement through the high-risk algorithm, with dual mobility implants being used in 143 of the cases. The researchers reported only one dislocation in this high-risk group (or 0.5% of high-risk patients), compared with 3.1% in the previous group not assessed with the risk assessment and treatment algorithm. These findings represent a six-fold decrease in the rate of dislocation in the high-risk group, the release continues.

“There were significantly fewer dislocations in the high-risk group when treated via our new treatment algorithm,” explains study co-author Aaron J. Buckland, MD, an assistant professor of orthopedic surgery in the Division of Spine Surgery and director of spine research at NYU Langone, in the release.

“We were able to prevent these implant dislocations from occurring in the first place, sparing our patients unplanned admissions, pain, disability, and revision surgery.”

Future studies aim to examine how the algorithm affects long-term outcomes and clinical benefits in patients at high risk for dislocation, according to the researchers.

[Source(s): NYU Langone Health, Newswise]