Table 2.
Univariate and multivariate analysis of variables associated with acquired idiopathic stiffness
| Variable | Unadjusted HR | 95% CI | p-value | Adjusted HR | 95% CI | p-value |
|---|---|---|---|---|---|---|
| Patient Characteristics | ||||||
| Sex | ||||||
| Female | 1.00 | 0.83 – 1.21 | 0.99 | 1.07 | 0.87 – 1.32 | 0.53 |
| Male (reference) | ||||||
| Age | ||||||
| < 65 years | 2.46 | 2.04 – 2.96 | <0.001 | 2.34 | 1.86 – 2.93 | <0.001 |
| ≥ 65 years (reference) | ||||||
| Body mass index | ||||||
| ≥ 30 kg/m2 | 0.93 | 0.77 – 1.12 | 0.43 | 0.80 | 0.64 – 0.99 | 0.04 |
| < 30 kg/m2 (reference) | ||||||
| Indication for TKA | ||||||
| Post-traumatic arthritis | 2.09 | 1.65 – 2.66 | <0.001 | 1.37 | 1.02 – 1.83 | 0.04 |
| Osteoarthritis (reference) | ||||||
| Smoking status | ||||||
| Current | 1.67 | 1.18 – 2.36 | 0.004 | 0.94 | 0.62 – 1.42 | 0.76 |
| Never (reference) | ||||||
| Prior knee surgery | ||||||
| Yes | 1.64 | 1.35 – 1.99 | <0.001 | 1.08 | 0.85 – 1.37 | 0.53 |
| No (reference) | ||||||
| Surgical Characteristics | ||||||
| Unilateral or Bilateral TKAs | ||||||
| Simultaneous bilateral | 0.66 | 0.46 – 0.96 | 0.03 | 0.78 | 0.70 – 0.88 | <0.001 |
| Staged bilateral | 0.45 | 0.33 – 0.61 | <0.001 | – | – | – |
| Unilateral (reference) | ||||||
| Anesthesia | ||||||
| General | 1.47 | 1.22 – 1.77 | <0.001 | 1.34 | 1.08 – 1.65 | 0.007 |
| Neuraxial (reference) | ||||||
| Tourniquet time, min | 1.01 | 1.01 – 1.01 | <0.001 | 1.01 | 1.00 – 1.01 | <0.001 |
| Operative time, min | 1.00 | 1.00 – 1.00 | <0.001 | 1.00 | 1.00 – 1.00 | 0.76 |
| Comorbidities^ | ||||||
| Diabetes | 1.17 | 0.94 – 1.45 | 0.17 | 1.53 | 1.20 – 1.96 | 0.001 |
| Hypertension | 0.57 | 0.47 – 0.69 | <0.001 | 0.78 | 0.62 – 0.97 | 0.03 |
| Peripheral vascular disease | 0.60 | 0.46 – 0.77 | <0.001 | 0.76 | 0.57 – 1.02 | 0.07 |
| Liver disease† | 1.29 | 0.73 – 2.29 | 0.38 | 1.61 | 0.90 – 2.87 | 0.11 |
| Metastatic solid tumor | 0.77 | 0.45 – 1.31 | 0.33 | 1.05 | 0.60 – 1.84 | 0.86 |
| Congestive heart failure | 0.61 | 0.42 – 0.88 | 0.01 | – | – | – |
| Renal disease† | 0.64 | 0.45 – 0.91 | 0.01 | – | – | – |
| Rheumatologic disease | 0.82 | 0.59 – 1.14 | 0.24 | – | – | – |
| Myocardial infarct | 0.75 | 0.51 – 1.09 | 0.13 | – | – | – |
| Other cancer | 0.84 | 0.66 – 1.07 | 0.15 | – | – | – |
| Cerebrovascular disease | 0.79 | 0.58 – 1.06 | 0.12 | – | – | – |
| Dementia | 0.66 | 0.34 – 1.28 | 0.22 | – | – | – |
| Chronic pulmonary disease | 0.99 | 0.80 – 1.22 | 0.90 | – | – | – |
| Mild liver disease | 1.14 | 0.85 – 1.51 | 0.39 | – | – | – |
| Diabetes with organ damage | 0.93 | 0.63 – 1.36 | 0.70 | – | – | – |
| Hemiplegia | 0.79 | 0.37 – 1.65 | 0.52 | – | – | – |
| Ulcer | 0.82 | 0.57 – 1.17 | 0.27 | – | – | – |
| CCI | 0.45 | 0.37 – 0.54 | <0.001 | – | – | – |
*
HR = Hazard Ratio; CI = Confidence Interval; TKA = Total Knee Arthroplasty; CCI = Charlson Comorbidity Index
^
Absence of disease served as reference for comorbidity data
†
Moderate or severe disease