Abstract
Summary Statement
Navigated total knee arthroplasty (TKA) is becoming increasingly popular in the United States. Compared to traditional unnavigated TKA, the use of navigation is associated with decreased blood transfusions and shorter hospital stays.
Introduction
Navigated total knee arthroplasty (TKA) is a recent modification to standard TKA with many purported benefits in regards to component positioning. Controversy currently exists though regarding its clinical benefits. The purpose of this study was to assess recent national trends in navigated and unnavigated total knee arthroplasty and to evaluate perioperative outcomes for each group.
Methods
International Classification of Disease - 9th Revision (ICD-9) procedure codes were used to search the National Hospital Discharge Survey (NHDS) for all patients admitted to US hospitals after navigated and unnavigated TKA for each year between 2005 and 2010. Data regarding patient demographics, hospitalization length, discharge disposition, blood transfusions, deep vein thrombosis, pulmonary embolism, mortality, and hospital location were gathered from the NHDS. Trends were evaluated by linear regression with Pearson's correlation coefficient (r) and statistical comparisons were made using Student's t-test, z-test for proportions, and chi-square analysis with a significance level of 0.05.
Results
22,443 patients admitted for TKA were identified. 578 (2.6%) of these patients had a TKA utilizing navigation. After adjusting for fluctuations in annual TKA performed, the use of navigation in TKA demonstrated a strong positive correlation with time (r=0.71), significantly increasing from an average utilization rate of 2.2% between 2005–2007 to 3.2% between 2008–2010 (p<0.01). The location of the hospital was found to significantly impact the utilization of navigation, with the lowest rate seen in the Midwest region (2.0%) of the US and the highest rate seen in the South region (3.0%).
The mean age of navigated patients was 66.0 years. This group included 211 men and 367 women. The unnavigated group had a mean patient age that was insignificantly higher at 66.4 years (p=0.37) and included 7,815 men and 14,047 women. Gender was also not significantly different (p=0.71) between those with navigated TKA and those with unnavigated TKA. The number of medical co-morbidities was significantly higher in those with navigation (mean 5.4 diagnoses) than those without navigation (mean 5.1 diagnoses, p=0.01). Average hospitalization length also varied based on navigation status, with significantly shorter stays for those with navigation (3.3 days, range 1–11) compared to those without (3.6 days, range 1–73, p<0.01). The rate of blood transfusion was significantly lower in the navigated group (13.0%) versus the unnavigated group (17.4%, p<0.01). There was no difference in the rate of deep vein thrombosis (0.69% vs 0.53%, p=0.64) or pulmonary embolism (0.17% vs 0.47%, p=0.10). Mortality was also not significantly different for navigated TKA (0.17%) when compared to unnavigated TKA (0.08%, p=0.61). Discharge disposition did not significantly vary based on navigation status either, with 65.5% of navigated patients and 67.0% of unnavigated patients able to go directly home (p=0.55) after their inpatient stay.
Discussion/Conclusion
This study demonstrates that the use of navigated TKA in the US is rising. Additionally, despite having more medical co-mobidities, the navigated population required less blood transfusions and shorter lengths of stay. Interestingly, navigation utilization demonstrated variability based on hospital region. The reasons for this are not immediately clear, but may be related to differences in regional training.
