Is inferior screw fixation a safe and reliable way of reducing acetabular component failure after revision total hip arthroplasty (THA) in cases of severe acetabular bone loss?
Inferior Screw Fixation Study Wins Technique & Technology Award
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“Yes” says a new award-winning study.
Led by Christopher M. Melnic, M.D. with co-authors Amy Z. Blackburn, B.A., Ashish Mittal, M.D., Brian Velasco, M.D., Colin M. Baker, D.O., Nicholas Vandal, B.A., Saad Tarabichi, M.D., P. Maxwell Courtney, M.D., Neil P. Sheth, M.D. and Hany S. Bedair, M.D., this new study of inferior screw fixation won the AAHKS Surgical Techniques and Technologies Award, which recognizes outstanding advancement in surgical innovation within reconstructive surgery.
“My co-authors and I are honored to receive the AAHKS Surgical Techniques and Technologies award for our manuscript on inferior screw fixation in revision total hip arthroplasty. In this multicenter, retrospective study, we found that the addition of inferior screw fixation for Paprosky Type II or III acetabular bone loss was associated with a lower rate of aseptic failure compared to fixation with superior screws alone,” said Dr. Melnic.
The researchers looked at 250 patients with Paprosky Type II or III defects who had acetabular revision from 2001-2021 (four institutions).
They collected data on demographic factors, the number of screws, location of screw placement (superior versus inferior), use of augments and/or cup-cage constructs, Paprosky classification and presence of discontinuity. Inferior screw placement was defined as placement in the superior pubic ramus or ischium based on radiographs.
At mean follow-up of 53.4 months, 16 patients (6.4%) required re-revision for acetabular loosening. There were 140 patients (56.0%) with inferior screw fixation, all without neurovascular complication during screw placement. Patients with inferior screws had a lower rate of acetabular re-revision than those with only superior screw fixation (2.1% vs. 11.8%). Multivariate regression revealed that inferior screw fixation decreased the likelihood of re-revision for acetabular loosening when compared to superior screw fixation only.
“The number of revision total hip arthroplasties continues to increase despite total hip arthroplasty being a very successful procedure,” said Dr. Melnic to OTW. “Revision total hip arthroplasty is complicated in the setting of acetabular bone loss. Successful treatment is predicated on achieving a stable construct which often necessitates the use of additional fixation. One additional fixation technique is the use of inferior screw fixation into the ischium or superior pubic ramus.”
“The use of inferior screw fixation into the ischium or the superior pubic ramus has been evaluated biomechanically where it was found to decrease micromotion of the cup and increase abduction stability.
Going forward, Dr. Melnic told OTW, “Additional focuses of research could include determining if screw length played a factor in stability of the construct and if a specific implant had an impact on the stability of the construct.”
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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