American Association of Hip and Knee Surgeons Annual Meeting
American Association of Hip and Knee Surgeons Annual Meeting
November 04, 2018
1 min read

Hip-spine classification system may decrease risk of recurrent hip instability

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Jonatan Vigdorchik
Jonathan M. Vigdorchik

DALLAS — Use of a hip-spine classification system in revision total hip arthroplasty may decrease the risk of recurrent instability, according to results presented at the American Association of Hip and Knee Surgeons Annual Meeting.

Jonathan M. Vigdorchik, MD, and colleagues matched 111 patients undergoing revision THA for recurrent instability using a new hip-spine classification system protocol to 111 patients undergoing revision for instability but not using the protocol.

“Protocol consisted of a supine and standing [anteroposterior] AP pelvis X-ray and standing and sitting lateral spinal pelvic view,” Vigdorchik said in his presentation here.

Patients in the protocol group were identified as having normal spinal alignment, flatback deformity or hyperlordosis with either normal spinal mobility or a stiff spine.

“Every group had a treatment based on whether the posterior dislocation or the anterior dislocation, based on what we thought the acetabular position was and how we could modify it accordingly,” Vigdorchik said.

Researchers found 104 posterior dislocations and seven anterior dislocations. There was an average of 2.6 dislocations prior to revision.

“The mean time to dislocation was 1.6 months, which is consistent with the fact that a majority of these hips dislocate within the first 30 days,” Vigdorchik said.

Vigdorchik noted a significant difference in standing cup anteversion vs. supine cup anteversion among patients who had anterior dislocation. All patients in the anterior dislocation group had flatback deformity, according to results. Spinal disease was identified in 75% of patients, Vigdorchik said. Of these patients, 26 patients had surgical fusion and 57 patients had spinal pathology without a fusion. He added 55% of patients with spinal pathology without a fusion had a stiff spine.

“Survivorship free of dislocations using these protocols is 97% in the revision cohort, this is up to 2.5 years,” Vigdorchik said.

He continued, “Our control group had an 84% survivorship and 18 dislocations.” – by Casey Tingle



Vigdorchik JM, et al. Paper 9. Presented at: American Association of Hip and Knee Surgeons Annual Meeting; Nov. 1-4, 2018; Dallas.


Disclosure: Vigdorchik reports he is a paid consultant for Corin U.S.A., Intellijoint Surgical and Stryker.