Using a new Hip-Spine Classification System in revision total hip arthroplasty significantly reduced the risk of recurrent instability, according to research presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16 in Las Vegas.
Four things to know:
1. The study authors collected data on 111 patients undergoing revision THA for recurrent instability between January 2014 and January 2017 at two institutions using the new protocol.
2. Protocol patients underwent standardized preoperative imaging, including a supine anteroposterior pelvis radiograph, standing anteroposterior pelvis and sitting and standing lateral radiographs. Each case was scored according to the "Hip-Spine Classification in Revision THA" as follows:
- Normal spinal alignment
- Flatback deformity
- Hyperlordosis, including normal spinal mobility and stiff spine
3. Survivorship free of dislocation at two years postoperatively was 97 percent in the protocol group compared to 84 percent in the control group.
4. Approximately 77 percent of the inappropriately positioned acetabular components would have gone unrecognized by supine anteroposterior pelvis imaging alone. All cases fell within one of the five categories of the classification system.