Elsevier

The Journal of Arthroplasty

Volume 32, Issue 10, October 2017, Pages 3184-3190
The Journal of Arthroplasty

Basic Science
What is the Impact of a Spinal Fusion on Acetabular Implant Orientation in Functional Standing and Sitting Positions?

https://doi.org/10.1016/j.arth.2017.04.051Get rights and content

Abstract

Background

This study used EOS imaging of primary total hip arthroplasty (THA) patients, with and without predating spinal fusion, to investigate (1) the impact of spinal fusion on acetabular implant anteversion and inclination, and (2) whether more extensive spinal fusion (fusion starting above the thoracolumbar junction or extension of fusion to the sacrum) affects acetabular implant orientation differently than lumbar only spinal fusion.

Methods

Ninety-three patients had spinal fusion (case group), and 150 patients were without spinal fusion (controls). None of the patients experienced dislocation. The change in sacral slope (SS) and cup orientation from standing to sitting was measured.

Results

Mean SS change from the standing to sitting positions was −7.9°in the fusion group vs −18.4°in controls (P = .0001). Mean change in cup inclination from the standing to sitting positions was 4.9°in the fusion group vs 10.2°in controls (P = .0001). Mean change in cup anteversion from standing to sitting positions was 7.1°in the fusion group vs 12.1°in controls (P = .0001). For each additional level of spinal fusion, the change in SS from standing to sitting positions decreased by 1.6(95% confidence interval [CI], 2.2073-1.0741), the change in cup inclination decreased by 0.8(95% CI, 0.380-1.203), and the change in cup anteversion decreased by 0.9(95% CI, 0.518-1.352; P < .001 in all cases).

Conclusion

Patients with spinal fusion demonstrated less adaptability of the lumbosacral junction. Longer spinal fusion or inclusion of the pelvis in the fusion critically impacts hip-spine biomechanics and significantly affects the ability to compensate in the standing-to-sitting transition.

Section snippets

Methods and Materials

This was a nonrandomized, retrospective, case-control study of consecutive patients who were assessed with EOS imaging and 3D Stereos reconstructions and who met our inclusion and exclusion criteria as presented in the next section. Patients were recruited by the Department of Orthopaedic and Trauma Surgery, Pitié-Salpétrière Hospital, between 2013 and 2015 on approval from the institutional review board.

The case group included all patients in our department who underwent primary THA with a

How Does Spinal Fusion Impact the Acetabular Implant Anteversion and Inclination?

Table 1 shows the measured parameters in patients (history of spinal fusion vs no spinal fusion). There was no substantial difference in cup inclination in standing position between the two groups (case: 47.4°, control: 46.4°; P = .3769). The mean standing SS (case: 32.4°, control: 39°; P = .0001), sitting SS (case: 24.6°, control: 20.6°; P = .008), sitting cup inclination (case: 52.3°, control: 56.4°; P = .007), standing cup anteversion (case: 32.1°, control: 21.7°; 0.0001), and sitting cup

Discussion

In this study, primary THA patients with different levels of previous spinal fusion were compared with THA patients who did not have spinal surgery using preoperative and postoperative 3D imaging in standing and sitting positions. The findings show the limited ability of patients with THA and predating spinal fusion to adapt the spinopelvic junction in a sitting/standing position, compared with patients without spinal pathologies. Even if the absolute mean values of cup anteversion are similar

Conclusion

This study shows the importance of assessing the lumbosacral junction during the physical examination of THA patients. Patients with lumbar spinal fusion have less adaptability of the lumbosacral junction. Inclusion of the thoracic spine or sacrum in spinal fusions has a critical impact on hip-spine biomechanics and significantly affects the ability to compensate during daily activities. This may result in hip subluxation, dislocations, or abnormal wear. We suggest precise evaluation of the

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    No author associated with this paper has disclosed any potential or pertinent conflicts which may be perceived to have impending conflict with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2017.04.051.

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