Generic Implant Positioning Technology Based on Hole Projections in X-Ray Images

Abstract

Implant placement plays a key role in trauma and orthopedics. In this paper a generic technological concept for implant positioning assistance is outlined. The system utilizes conventional radiographic devices for imaging and tracking and embeds into surgical workflows without the need for complex navigation equipment. It is based on feature extraction from cylindrical hole-projections in X-ray images for determining spatial alignment of implant and anatomy. Basic performance of a prototype system was experimentally verified in terms of tracking accuracy and robustness under varying conditions. In a second step the system was developed into a set of application modules, each serving a pressing clinical need: Plating of the proximal humerus, cephalic nail and dynamic hip-screw placement, general anatomic plating, distal nail interlocking with adjustment of femoral anteversion and corrective osteotomies. Module prototypes were tested according to their degree of maturity from feasibility assessment in wet-labs to clinical handling tests. Orientation tracking of reference objects yielded an accuracy and precision of 0.1 ± 0.71° (mean ± standard deviation) with a maximum error of 4.68° at unfavorable conditions. This base-performance translated e.g. into a precision of ±1.2mm (standard deviation) screw-tip to joint distance at proximal humerus plating, or into a precision of lag screw positioning in the femoral head of ±0.6mm in craniocaudal and ±1.6mm in anterioposterior direction. The concept revealed strong potential to improve surgical outcomes in a broad range of orthopedic applications due to its generic and simplistic nature. Comprehensive validation activities must follow for clinical introduction.

Locking Plates With Computationally Enhanced Screw Trajectories Provide Superior Biomechanical Fixation Stability of Complex Proximal Humerus Fractures

“…While the statistical finding of the FE-Planned and FE-Achieved analyses was the same concerning the superiority of the EH versus the OG design, the simulations revealed similar results for the OG-Planned and EH-Achieved groups, indicating that the benefit of trajectory improvement was comparable to the loss of experimental imperfections. These findings emphasize the relevance of intraoperative navigation and guidance that could help surgeons to accurately execute the preoperative plan (Windolf and Richards, 2021). Such technologies are expected to help lowering complication rates of proximal humerus fracture fixations.…”

“…Additionally, the humeral heads were required to be large enough to accommodate the calcar screws (Row E, Figure 2 ) of the OG configuration. The corresponding evaluation was performed on anterior-posterior C-arm images of the intact bones using an in-house developed implant navigation system ( Windolf and Richards, 2021 ). Nine pairs (donor age: 85.3 ± 5.2 years, range: 73–91 years) fulfilled all criteria and were selected and scanned via high-resolution peripheral computed tomography (HR-pQCT, XtremeCT, Scanco Medical AG, Brüttisellen, Switzerland) with 60 kVp voltage, 900 µA current and 82 µM isotropic voxel size.…”

Application of Virtual Reality Systems in Bone Trauma Procedures

“…DEHST is a novel modular surgical skills training and evaluation system incorporating digital tools with haptic stations for hands-on learning. Position and orientation may be tracked in six directions from a single plane of the projected image using a specialised optical tracking technique [ 96 ].…”

Validity of a Novel Digitally Enhanced Skills Training Station for Freehand Distal Interlocking

“…It augments haptic stations for hands-on training with digital technologies to enhance training scope and improve user experience. A proprietary optical tracking technology is utilized to allow position and orientation tracking in 6 degrees of freedom from a single planar image projection [22]. This tracking technology is adapted for use with a conventional video camera [23], enabling tracking of the specific movements during surgical tasks and providing comprehensive performance analysis in low-cost fashion.…”

“…Based on the alignment of the C-arm and by pressing a footswitch, reconstructed radiographs are generated out of a computed tomography (CT) volume (Figure 2). The C-arm's position and orientation are calculated by the tracking system using the optical camera (2) and reference markers (1) with cylindrical holes [22,23]. A virtual representation of an intramedullary tibia nail is superimposed in the radiographic image and displayed on the computer's screen (3).…”