The Rise of the Direct Anterior Approach: Trends, Learning Curves, and Patient Characteristics of 63,182 Primary Total Hip Arthroplasties in the Dutch Arthroplasty Register (LROI).

BACKGROUND: The use of the anterior approach (DAA) in total hip arthroplasty (THA) has steadily increased in the Netherlands since 2007. The aim of this study was to outline how the DAA has been implemented in the Netherlands. Moreover, we investigated the learning curve of the DAA at a hospital level, and explored patient characteristics of the DAA compared with other approaches and during the learning phase after implementing the DAA.

METHODS: In this population-based cohort study we included all primary THAs between 2007 and 2020 (n= 342,473) from the Dutch Arthroplasty Register. For hospitals implementing the DAA (n>20), patients were categorized in four experience groups using the date of surgery: 1 to 50, 51 to 100, 101 to 150 or >150. Subsequently, data from different hospitals was pooled and survival rates were calculated using Kaplan-Meier survival analyses. Adjusted revision rates were calculated using mixed Cox proportional hazard models (frailty).

RESULTS: The use of the DAA gradually rose from 0.2% in 2007 to 41% of all primary THAs in 2020. A total of 64 (56%) hospitals implemented the DAA. However, not all hospitals continued using this approach. After implementation, the 5-year survival rate for the first 50 procedures was significantly lower (96% (Confidence Interval (CI) 95.8 to 97.2)) compared to >150 procedures (98% (CI 97.7 to 98.1)). Multivariable Cox hazard analyses demonstrated a higher risk of revision during the first 50 procedures compared with >150 procedures (Hazard Ratio 1.6, CI 1.3 to 2.0).

CONCLUSION: The use of DAA for primary THA significantly increased. For hospitals implementing DAA, a significant learning curve with increased revision risk was seen.