High Offset Stems are Protective of Dislocation in High Risk Total Hip Arthroplasty

5 pages•Published: September 25, 2020

Jonathan Vigdorchik, Abhinav Sharma, Ameer Elbuluk, Kaitlin Carroll, David Mayman and Jay Lieberman

Abstract

Background: Spinal stiffness has been shown to increase risk of dislocation due to impingement and instability. Increasing anteversion of the acetabular component has been suggested to prevent dislocation, but little has been discussed in terms of femoral or global offset restoration. The purpose of this study is to quantify dislocation rates after primary THA using standard versus high offset femoral components and to determine how differences in offset affect impingement-free range of motion in a stiff spine cohort using a novel impingement model. Methods: 12,365 patients undergoing THA from 2016-2018 were retrospectively reviewed to determine dislocation rates and utilization of standard versus high offset stems. For 50 consecutive patients with spinal stiffness, a CT-based computer software impingement modeling system assessed bony or prosthetic impingement during simulated range of motion. The model was run 5 times for each patient with varying offsets. Range of motion was simulated in each scenario to determine the degree at which impingement occurred. Results: There were 51 dislocations for a 0.41% dislocation rate. Total utilization of high offset stems in the entire cohort was 49%. Of those patients who sustained a dislocation, 49 (96%) utilized a standard offset stem. The impingement modeling demonstrated 5 degrees of added range of motion until impingement for every 1mm offset increase. Conclusion: In the impingement model, high offset stems facilitated greater ROM before bony impingement and resulted in lower dislocation rates. In the setting of high-risk THA due to spinal stiffness, surgeons should consider the use of high-offset stems and pay attention to offset restoration.

Keyphrases: dislocation, hip spine, impingement, offset, spinal deformity, stiff spine, total hip arthroplasty

In: Ferdinando Rodriguez Y Baena and Fabio Tatti (editors). CAOS 2020. The 20th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery, vol 4, pages 273-277.

Links:	https://easychair.org/publications/paper/1cRt
	https://doi.org/10.29007/bpfs

BibTeX entry

@inproceedings{CAOS2020:High_Offset_Stems_are,
  author    = {Jonathan Vigdorchik and Abhinav Sharma and Ameer Elbuluk and Kaitlin Carroll and David Mayman and Jay Lieberman},
  title     = {High Offset Stems are Protective of Dislocation in High Risk Total Hip Arthroplasty},
  booktitle = {CAOS 2020. The 20th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery},
  editor    = {Ferdinando Rodriguez Y Baena and Fabio Tatti},
  series    = {EPiC Series in Health Sciences},
  volume    = {4},
  publisher = {EasyChair},
  bibsource = {EasyChair, https://easychair.org},
  issn      = {2398-5305},
  url       = {/publications/paper/1cRt},
  doi       = {10.29007/bpfs},
  pages     = {273-277},
  year      = {2020}}

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