Does the Surgical Approach Affect the PJI Rate in Total Hip Arthroplasty?
A recently published, award-winning study compared rates of periprosthetic joint infection among patients whose surgeons used the direct anterior approach versus those whose surgeons used other approaches.
Nolan A. Maher, MD, and William J. Long, MD, FRCSC
Aggarwal VK, Weintraub S, Klock J, et al. 2019 Frank Stinchfield Award: A comparison of prosthetic joint infection rates between direct anterior and non-anterior approach total hip arthroplasty. Bone Joint J 2019 Jun;101-B(6_Supple_B):2-8. doi: 10.1302/0301-620X.101B6.BJJ-2018-0786.R1.
Recent studies have examined the rates of wound complications and infection associated with the direct anterior versus the posterior approach, with mixed results: Some studies have demonstrated an increased risk of surgical site infection with the anterior approach, while others have shown no significant differences.
The study by Aggarwal et al used a larger cohort of patients than previous studies to evaluate the risk of periprosthetic joint infection (PJI) in patients undergoing primary total hip arthroplasty (THA) utilizing the direct anterior approach versus all other surgical approaches.
This single-center study identified a cohort of 6086 patients who underwent primary THA between 2013 and 2016. The direct anterior approach was utilized in 1985 cases; other approaches to the hip were used in 4101 patients. The primary endpoint of the study was the diagnosis of PJI within 90 days of surgery, based on established criteria from the Centers for Disease Control’s National Healthcare Safety Network (CDC/NHSN).
In addition, the study sought to identify individual risk factors for PJI and to evaluate the impact of an infection prevention protocol adopted during the study period.
The patient-specific and surgical risk factors examined included:
- Age over 65 years
- BMI over 35
- Diabetes mellitus
- Alcohol use
- Operative time over 120 minutes
- High-volume surgeon (more than 100 cases per year)
- Same-day discharge
The infection-related outcomes included:
- Readmission for issue related to the hip
- Readmission due to symptoms relating to hip infection
- Return to the operating room
- Presence of PJI (CDC/NHSN criteria)
The individual risk factors were evaluated for differences between the direct anterior and other approaches groups, as well as the infected and non-infected groups.
Only BMI over 35 and presence of diabetes mellitus differed between the direct anterior and other approach groups and were the only 2 risk factors that increased the likelihood of PJI. Both risk factors were more prevalent in the other approaches group. These potentially confounding variables were later used in a multivariate analysis in the calculation of an adjusted odds ratio.
The overall rate of PJI was found to be 0.82% (50/6086). The direct anterior approach was found to confer a significantly higher risk of PJI than the other approaches (1.2% vs 0.6%). When adjusted for BMI and presence of diabetes mellitus, patients who underwent primary THA through the direct anterior approach were 2.2 times more likely to develop a PJI within 90 days of surgery than patients in the others approach group (95% CI 1.1-3.5; P=0.006).
Additional analysis of the data failed to reveal any significant reductions in the PJI rate over the study period that could be attributed to the changes in hospital protocols regarding anticoagulation and infection prevention.
There is growing evidence that the direct anterior approach may put patients at higher risk for early complications, including wound healing issues, early femoral component revision, and now early PJI. The paper by Aggarwal et al is the largest cohort examining infection rates associated with the direct anterior approach versus other approaches to THA. It is also one of the few studies in the literature where a multivariate analysis was performed in an attempt to eliminate any confounding variables for PJI and the surgical approach.
Limitations noted in this study include its retrospective nature, non-standardized levels of surgeon experience, and potential underpowering. Although a difference was found in the overall infection rates, the authors mention that the lack of statistical significance regarding the changes in anticoagulation and infection prevention protocols may be due to the relative scarcity of PJI events. This relative scarcity suggests that future research should be focused on large cohorts and registry data to identify patient-specific and surgical risk factors for PJI.
In conclusion, patients who underwent primary THA with the direct anterior approach were found to have a 2.2 times higher likelihood of early PJI than patients who underwent THA with other approaches to the hip. This fact should be an important consideration for surgeons when evaluating the benefits and drawbacks of each surgical approach, especially given the significant morbidity and financial costs associated with PJI.
Nolan A. Maher, MD, is an adult reconstruction fellow in the Department of Orthopaedic Surgery at NYU Langone Health, New York, New York. William J. Long, MD, FRCSC, is a Clinical Associate Professor in the Department of Orthopaedic Surgery at NYU Langone Health. He is also a Director and Chief of Research for the Insall Scott Kelly Institute for Orthopaedics and Sports Medicine, New York, New York.
Disclosures: The authors have no disclosures relevant to this article.