Vector vision

All patients received a unilateral primary CAS-TKA by a single experienced surgeon. A pneumatic tourniquet was inflated to 300 mmHg pressure before the incision and deflated at the end of surgery after skin closure. No patient received preoperative tranexamic acid. The distal femur and proximal tibia bone cut were performed in an extramedullary manner. The navigation system was Vector Vision (BrainLab, Heimstetten, Germany), and all TKAs were cemented using the same prosthesis (NexGen Legacy posterior-stabilized prosthesis; Zimmer Inc., Warsaw, IN, USA). There was no local infiltration of the local anesthetic in the knee joint. A suction drain was inserted before wound closure and removed on postoperative day (POD) 1. All surgical wounds, including the stab incisions for the insertion of temporary pins, were closed with interrupted skin stitches. All patients received aspirin (100 mg once daily) as venous thromboembolism (VTE) prophylaxis for 14 days. Every patient was encouraged to do early and protected weight-bearing after the surgery on the same day or the POD 1 to avoid VTE complications [23 (link)]. Mechanical prophylaxis, such as intermittent pneumatic compression, was not performed in this study. Multimodal pain management, such as acetaminophen, cyclooxygenase-2 inhibitors drugs, and tramadol/acetaminophen combination tablets [Ultracet], was applied for all patients.

All operations were performed by two senior surgeons. Our institution adopts two different computer-assisted surgery (CAS) techniques or conventional surgical techniques when performing TKA in patients with hemophilia. According to surgeon preference, one adopted the computer navigation system (Vector Vision; BrainLAB, Munich, Germany) and the other used a robot-assisted system (ROBODOC, Integrated Surgical Systems, Davis, CA, USA) alternatively. For robot TKA, a single product in each cruciate-retaining (CR) and posterior-stabilized (PS) type was available due to the uploaded system. When CAS techniques were not possible and abandoned during the TKA procedure, we completed the surgery by converting to the conventional technique using the Vanguard knee system (Biomet, Inc., Warsaw, IN, USA). The types of prosthetic components that were used are shown in Table 2.

Before the neurosurgical procedure, MRI was performed on the head using a 1.5-tesla MR scanner (Signa Excite; GE Medical Systems, Milwaukee, WI, USA) to identify and locate the STN within the brain. Three MRI sequences were obtained: T₁-weighted (T₁W) axial images (repetition time [TR]: 26 ms; echo time [TE]: 6.9 ms; matrix size: 256 × 192; thickness: 0.7 mm), fast spin echo (FSE) T₂-weighted (T₂W) axial images (TR: 4,800 ms; TE: 95 ms; field of view (FOV): 24 cm; matrix size: 256 × 192; thickness: 2.0 mm) and coronal images (TR: 5,000 ms; TE: 102 ms; FOV: 20 cm; matrix size: 256 × 192; thickness: 3.0 mm). Data were acquired in contiguous slices. Through the picture archiving and communication system (PACS), brain MRI images were transferred to the neuronavigation workstation (VectorVision; Brainlab, Westchester, IL, USA). Targets and trajectories were planned based on the three sets of images using the VectorVision neuronavigation system. Tentative surgical target coordinates for the tip of the implantable electrode were set centrally on the lowest border of the STN using direct visualization on MRI images as previously described (Chen et al., 2006 (link)).