Evaluating Neutral Mechanical Alignment and Durability in Revision TKA
Does neutral mechanical alignment – defined as postoperative mechanical axis of 0°±3° – result in better long-term implant durability and positive functional outcomes for patients who undergo revision total knee arthroplasty (TKA)?
Researchers from Mayo Clinic in Rochester, Minnesota, hypothesized that it would, and they tested that hypothesis with a retrospective study of a large cohort of revision TKAs done at their institution between 2004 and 2014. Their findings were presented at the 2018 Annual Meeting of the American Association of Hip and Knee Surgeons.
They researchers had performed 981 revisions in 846 patients in this 10-year period using cemented varus-valgus constrained implants. They included in the study 411 knees (42%) for which they had pre- and post-revision hip-knee-ankle radiographs to review. The researchers compared aseptic loosening, re-revisions, and Knee Society Scores 2 patient groups:
- 258 neutrally aligned knees with a postoperative mechanical axis of 0°±3°
- 153 outlier knees with a postoperative mechanical axis between 4°and 12° varus and 4° and 10° valgus
They found no difference in functional outcomes or 10-year implant survivorship in the neutrally aligned group versus the outlier group, leading the researchers to conclude that, “while neutral mechanical alignment remains a useful goal in revision total knee arthroplasty, factors other than static coronal alignment may be as important in determining durability.”
Abdel MP, Reina N, Salib CG, Trousdale RT, Berry DJ, Pagnano MW. Does Neutral Mechanical Alignment Improve the Durability of Revision Total Knee Arthroplasty? (Paper #36). Presented at the 2018 Annual Meeting of the American Association of Hip & Knee Surgeons, November 1-4, 2018, Dallas, Texas.