Coronal plane deformity in total knee arthroplasty is associated with increased operative time and disposition to...

Studies demonstrate similar long-term Total Knee Arthroplasty (TKA) outcomes in patients with significant versus minimal preoperative coronal plane deformity. Limited short-term outcomes data, which determine costs of care, exist.

We retrospectively explored the impact of preoperative coronal plane deformity on operative time, length of stay (LOS), and discharge to skilled nursing facility (SNF) in TKA. A total of 3,964 patients undergoing unilateral primary TKA at our institution from 2014 to 2019 were included (1,158 > 10˚ deformity: mean age 67.2 years, 47% male; 2,806 < 10˚ deformity: mean age 67 years, 37.4% male). The degree of coronal plane deformity (mechanical axis deviation on preoperative radiographs) was recorded. Patients with no knee radiographs ≤ 3 years preoperatively were excluded. Statistical analysis included Chi-Square tests, Student's t-tests, Mann-Whitney U tests, and uni- and multivariable linear and logistic regression analyses.

The > 10˚ deformity cohort had a longer time from procedure start to finish (113.56 vs. 110.68 min; p = 0.020), greater deviation from surgeon mean operative time (+ 6.19 vs. + 0.69 min; p < 0.001), and higher proportion of cases requiring > 15 (26.8% vs. 22%;p = 0.001) and > 30 (12.3% vs. 7.8%;p < 0.001) additional minutes over their scheduled times. LOS was similar between cohorts (median 2 days, IQR 1-3). The deformity cohort more likely discharged to SNF (19.9% vs. 15.8%;p = 0.002). For every 1˚ increase in coronal plane deformity, operative time increased by 0.566 min (p = 0.000). The odds of SNF discharge increased with increasing coronal plane deformity (OR 1.029 [1.009,1.050]; p = 0.004).

Greater preoperative coronal deformity is associated with increased operative time and odds of discharge to SNF in TKA.