Surgical Outcomes of Three vs Four Arm Robotic Partial Nephrectomy: Is the Fourth Arm Necessary?

Objective: To compare the cost, efficacy, and safety of 3-arm versus 4-arm technique in robotic partial nephrectomy (RPN). Surgeons may either elect to utilize three vs four robotic instruments depending on preference. The purpose of this study is to compare the outcomes between the two techniques. Methods: RPNs from June 2016 to August 2017 were retrospectively reviewed. Tumor features, surgical parameters, and operative outcomes were evaluated. The number of arms used was determined. Statistical analysis was performed with the Student's t test, chi-squared, and Mann-Whitney test. Results: A total of 61 consecutive 3-arm RPNs and 59 consecutive 4-arm RPNs were evaluated. Mean tumor diameter and median nephrometry score were 3.4 cm (± 1.1 SD) and 7 (6-8 IQR) for the 3-arm group and 3.3 cm (±1.2 SD) and 6 (5-8 IQR) for the 4-arm group, respectively (size: p = 0.7, nephrometry: p = 0.07). Hospital length of stay, operative time, estimated blood loss, complication rate, blood transfusion rate, and readmission rate all demonstrated no statistically significant difference between 3-arm and 4-arm groups (p >0.05). Mean ischemia time was shorter by 5.1 minutes in the 4-arm group (p = 0.02). Rate of margin positivity was higher in the 4-arm group (0% vs 10%, p = 0.03). Conclusion: RPN can be safely and effectively completed with 3-robotic arms. While there was increased ischemia time, the difference was small and likely not of clinical significance. The routine addition of the fourth robotic arm in RPN is not necessary.