Page 144 - Demo

Chapter 7142In total hip and knee arthroplasty, the use of 3D-printed patient-specific instruments (PSI) has shown added value in the form of high accuracy.8,21However, no demonstrable improvement in patient reported outcome, and surgery time or transfusion rate has been shown when using PSI compared to standard total knee arthroplasty.13 As exact anatomic reconstruction within a 2mm range of the native ACL footprint already has shown to have a significant relation with graft failure, the accurateness provided using PSI in ACL reconstruction may have more noticeable effects.The accuracy of femoral tunnel placement has been studied extensively before. An empirical optimal point for femoral tunnel position has been determined based on cadaver studies at a point at 28% on the proximal-todistal axis and 35% on the perpendicular axis.2 It has been shown that when surgeons rely on anatomical landmarks alone, a mean deviation of 12.5 mm occurs with respect to this empirical optimal point.10 This emphasizes that current, widespread used surgical techniques fail to recreate the native ACL. The use of intra-operative fluoroscopy can improve accuracy, but still a mean deviation of 9.8 mm remains. Other reports show that an experienced surgeon can obtain a deviation of 4.2 mm of the femoral origin when using arthroscopy alone, which can improve to 2.7 mm when using intra-operative navigation.20 Additive value in ACL reconstruction in terms of accuracy of femoral tunnel placement was shown using computer assisted surgery (CAS).4,16,20 The use of CAS during ACL reconstruction has been shown to lead to a deviation of planned tunnels of approximately 2 mm, in which 1 mm is attributed to the overall robotic system and 1 mm to intra-operative movement of the patient. Disadvantages of CAS include the learning curve and time consumption during surgery. With our newly developed PSI system we strive for comparable results in terms of accuracy,while at the same time using a simpler and more practical construct. The main difference between a CAS/Fluoroscopy based approach and a PSI concept is that PSI strives for an individual anatomic approach rather than a one size fits all approach which leads back to an empirical determined point averaged over multiple cadaveric studies.2,10 It is therefore that our selected point cannot be compared to this empirical optimal point, as we never aimed for the empirical optimal point.Mark Zee.indd 142 03-01-2024 08:56