Table 3 Multiple linear regression models predicting prolonged length of stay in UKA patients

Model 1: Conventional UKA vs. robotic-assisted UKA

Dependent variable: ALOS

Model Summary

(number of patients analysed, n = 1255)

R

R²

R² adjusted

Standard error of estimate

P-value

Independent variables

0.208

0.043

0.036

2.45

 < 0.001^†

Unstandardized Beta

Standard error

Standardized β

t-test statistic

P-value

Robotic-assisted UKA

 − 0.106

0.175

 − 0.017

 − 0.602

0.547

Laterality (Bilateral UKA)

0.650

0.171

0.106

3.791

 < 0.001^†

Age

0.017

0.011

0.045

1.615

0.107

Gender (male)

 − 0.061

0.142

 − 0.012

 − 0.433

0.665

Hypertension

0.142

0.191

0.023

0.742

0.458

Diabetes mellitus

 − 0.053

0.245

 − 0.006

 − 0.215

0.830

CKD

3.326

0.545

0.171

6.101

 < 0.001^†

Obesity (BMI > 25)

 − 0.119

0.143

 − 0.023

 − 0.833

0.405

Hyperlipidemia

0.064

0.212

0.009

0.301

0.764

Model 2: Conventional UKA vs. Mako UKA

Dependent variable: ALOS

Model Summary

(n = 1190)

R

R²

R² adjusted

Standard error of estimate

P-value

Independent variables

0.210

0.044

0.037

2.46

 < 0.001^†

Unstandardised Beta

Standard error

Standardised β

t-test statistic

P-value

Mako UKA

 − 0.392

0.199

 − 0.056

 − 1.973

0.049^†

Bilateral UKA

0.513

0.177

0.083

2.898

0.004^†

Age

0.016

0.011

0.041

1.429

0.153

Gender (male)

 − 0.025

0.146

 − 0.005

 − 0.171

0.864

Hypertension

0.110

0.196

0.018

0.564

0.573

Diabetes mellitus

 − 0.028

0.250

 − 0.003

 − 0.112

0.911

CKD

3.341

0.546

0.176

6.114

 < 0.001^†

Obesity (BMI > 25)

 − 0.165

0.147

 − 0.032

 − 1.128

0.260

Hyperlipidemia

0.073

0.219

0.010

0.336

0.737

Model 3: Conventional UKA vs. Navio/Cori UKA

Dependent variable: ALOS

Model Summary

(n = 1073)

R

R²

R² adjusted

Standard error of estimate

P-value

Independent variables

0.215

0.046

0.038

2.54

 < 0.001^†

Unstandardized Beta

Standard error

Standardized β

t-test statistic

P-value

Navio/Cori UKA

0.715

0.326

0.066

2.190

0.029^†

Bilateral UKA

0.519

0.193

0.081

2.688

0.007^†

Age

0.016

0.012

0.040

1.319

0.188

Hypertension

0.138

0.211

0.021

0.654

0.514

Diabetes mellitus

0.034

0.265

 − 0.004

 − 0.126

0.899

CKD

3.594

0.595

0.183

6.040

 < 0.001^†

Obesity

 − 0.151

0.159

 − 0.029

 − 0.946

0.344

Hyperlipidemia

0.126

0.237

0.017

0.531

0.596