The following study evaluated blood loss in patients undergoing navigation-assisted minimally invasive total knee arthroplasty. The study included 100 patients divided into two groups. Group A consisted of patients with an immediate drain release, and group B consisted of patients with a 1-hour delayed drain release after surgery. The surgeon used a mini-midvastus approach with the OrthoPilot navigation system. The mean blood drainage was 465 mL in group A and 409 mL in group B. The mean hemoglobin loss was 2.59 g/dL in group A and 2.43 g/dL in group B.