Increasing Coronal Deformity, Tibiofemoral Subluxation And More Severe Bone Defects Are Risk Factors For To The Use Of A Higher-Constrained Total Knee Arthroplasty

Increasing Coronal Deformity, Tibiofemoral Subluxation And More Severe Bone Defects Are Risk Factors For To The Use Of A Higher-Constrained Total Knee Arthroplasty

Sandro Hodel, MD, SWITZERLAND Patrick Pflüger, MD, SWITZERLAND Lukas Jud, MD, SWITZERLAND Juliette Wälchli, SWITZERLAND Francesca Napoli, MD, SWITZERLAND Lazaros Vlachopoulos, MD, PhD, SWITZERLAND Sandro Fucentese, Prof MD, SWITZERLAND

Balgrist University Hospital, Zurich, SWITZERLAND


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Anatomic Location

Anatomic Structure

Diagnosis / Condition

Patient Populations

Diagnosis Method


Summary: Analysis of predictors for a higher-constrained total knee arthroplasty was performed in a retrospective single-center analysis of 1062 knees. Increasing coronal deformity, tibiofemoral subluxation and more severe bone defects are predictive for the use of a higher-constrained TKA in the primary setting.


Background

In primary total knee arthroplasty (TKA), the preoperative assessment of knee stability and the need for a higher-constrained TKA remains challenging. The aim of the study was to (1) analyze risk factors for the use of a higher-constrained TKA and to (2) assess functional outcome.

Methods

Retrospective single-center analysis of 903 consecutive patients (n=1062 knees) that underwent a primary TKA using a patient-specific instrumentation system allowing intraoperative crossover to a higher-constrained TKA between 2015 and 2020 was conducted. Radiographic (hip-knee-ankle angle (HKA), joint line convergence angle (JLCA), coronal tibiofemoral (TF)-subluxation and bone defects) and demographic predictors (age, sex, and body-mass index (BMI)) for the use of a higher-constrained TKA were analyzed. Knee society score (KSS) and revision rates were assessed.

Results

In 77 out of 1062 knees (7.3%) an intraoperative crossover to a higher-constrained TKA was performed, resulting in 15 semi-constrained and 62 hinged TKAs. In varus knees, HKA (cut-off: <167.3°, OR: 10.0, 95% CI: 4.7-21.4; p<0.001), TF-subluxation (cut-off: >7.5 mm, OR: 5.4; 95% CI: 2.7-11.0; p<0.001) and bone defect (cut-off: ≥Grade 1, OR: 6.9 ;95% CI: 3.2-14.9; p<0.001) were significant preoperative risk factors for an intraoperative crossover. For valgus knees, HKA (cut-off: >193.8°, OR: 14.3; 95% CI: 7.0-29.4; p<0.001) and TF-subluxation (cut-off: >7.3 mm, OR: 3.5; 95% CI: 1.6-7.5; p<0.001) remained significant risk factors. The revision rate and KSS scores did not differ between primary and higher-constrained TKAs 1 year postoperatively.

Conclusion

Increasing coronal deformity, tibiofemoral subluxation and more severe bone defects are predictive for the use of a higher-constrained TKA in the primary setting. The identified risk factors allow for a more precise surgical planning and anticipation of the use for a higher-constrained TKA. Crossover to a higher-constrained TKA does not impair functional outcome or increase complications in the short term.