Fluoroscopy-based computer-assisted navigation for implant placement and hip resurfacing arthroplasty in the proximal femur: the zero-dose C-arm navigation approach.

Abstract In the proximal femur, a high accuracy of implant placement reduces the risk of mechanical failure. We have tested a new computer-assisted planning and navigation system based on two-dimensional fluoroscopy using the so-called zero-dose C-arm navigation approach to optimise implant placement in fracture fixation and hip resurfacing. The aim of this review is to compare the results of this system with the current literature. Use of the novel system enables a minimally invasive approach to the hip and results in enhanced accuracy of implant placement compared with conventional techniques. Its precision is comparable to navigation systems currently in the market. The new system reduces irradiation but requires more operation time in comparison with established navigation systems. We believe zero-dose C-arm navigation can effectively be used to support surgeons in modern orthopaedic and trauma surgery departments, and can sufficiently serve the demands of both sections, especially at a time focusing on saving costs.

Three-dimensional computer-assisted navigation for the placement of cannulated hip screws. A pilot study.

PURPOSE: Medial femoral neck fractures are common, and closed reduction and internal fixation by three cannulated screws is an accepted method for the surgical treatment. Computer navigation for screw placement may reduce fluoroscopy time, the number of guidewire passes and optimise screw placement. METHODS: In the context of a sawbone study, a computer-assisted planning and navigation system based on 3D-imaging for guidewire placement in the femoral neck was tested to improve screw placement. Three screws were inserted into 12, intact, femoral sawbones using the conventional technique and into 12, intact, femoral sawbones guided by the computer-based navigation system. Guidewire and subsequent screw placement in the femoral neck were evaluated. RESULTS: Use of the navigation system resulted in a significant reduction of the number of drilling attempts (p≤0.05) and achieved optimised accuracy of implant placement by attaining significantly better screw parallelism (p≤0.05) and significantly enlarged neck-width coverage by the three screws (p≤0.0001). Computer assistance significantly increased the number of fluoroscopic images (p≤0.001) and the operation time (p≤0.0001). CONCLUSIONS: Three-dimensional computer-assisted navigation improves accuracy of cannulated screw placement in femoral neck while increasing the number of fluoroscopic images and operation time. Additional studies including fractured sawbones and cadaver models with the goal of reducing operation time are indispensable before introduction of this navigation system into clinical practice.

[Fluoroscopic navigation versus conventional manual positioning of the femoral component for hip resurfacing: first experimental trial]. / Fluoroskopische Navigation versus konventionelle manuelle Positionierung der Femurkomponente beim Oberflächenersatz der Hüfte: erste experimentelle Erprobung.

BACKGROUND: The most essential improvement of modern hip resurfacing arthroplasty is the metal-on-metal bearing as well as the integration of a procedure for the exact and repeatable positioning of the femoral component through a specific mechanical alignment instrument. Nevertheless, the main reasons for early implant failure are mal-positioning of the femoral component and notching of the femoral neck during femoral head preparation. MATERIALS AND METHODS: In the context of an in vitro study, in each case six DUROM-Hip resurfacing prostheses were implanted in artificial femora with the prosthesis-specific mechanical alignment instrument, as well as under navigation control. The aim of the study was to evaluate the functionality and accuracy of a computer-assisted planning and navigation system on the basis of a navigation module library from Surgitaix AG (Aachen, Germany), as well as a comparison with the prosthesis-specific mechanical alignment instrument. RESULTS: The main angulation error between planning and navigation of the stem-shaft angle was 0.2+/-1.2 degrees for the navigation system and 6.5+/-4.1 degrees for the mechanical alignment instrument, the main anterior offset error was 1.2+/-1.2 mm vs. -0.83+/-4.1 mm. The mean time for all five planning and navigation steps was 17+/-1.2 min vs. 14+/-0.8 min. The main distance error between planning and navigation was 1.9+/-0.6 mm for the navigation system, and 5.3+/-2.4 mm for the mechanical alignment instrument. Femoral notching was not observed for navigational or conventional positioning. CONCLUSION: The computer-assisted fluoroscopic planning and navigation system for hip resurfacing showed, within the scope of this in vitro study, first promising experiences. The system approves a practicable planning with a high accuracy in implementation. Nevertheless, the potential benefit has to be evaluated in further clinical studies, especially from the perspective of a possible integration of this navigation system into the clinical workflow. Further studies should consider a fluoroscopy-assisted range of motion assessment under consideration of an additional cup-module to enhance the postoperative range of motion after hip resurfacing procedures.

Fluoroscopic navigation system for hip surface replacement.

Metal-on-metal hip resurfacing arthroplasties represent an alternative to total hip arthroplasties for young and active patients, enabling the preservation of intact femoral bone and therefore improving the prognosis for future hip joint replacements. Follow-up studies have shown that the main reasons for early implant failure are mal-orientation of the implant stem in relation to the femoral neck axis, and notching of the femoral neck during femoral head preparation, as well as by exposed cancellous bone after implantation. A computer-assisted planning and navigation system for the implantation of femoral hip resurfacing implants has been developed which supports the surgeon during intraoperative fluoroscopy-based planning and navigation of implant positioning. This paper presents the results of a cadaver study performed to evaluate the system's functionality and accuracy.

Computer-assisted optimization of correction osteotomies on lower extremities.

Automated methods are presented for the planning of correction osteotomies and osteosynthesis on lower extremities. Intraoperative calibrated X-ray images and kinematic measurements using optical tracking systems are the basis for the identification of the individual anatomy of the patient. The correction input of the surgeon, together with optimization algorithms, allows the calculation of the position and orientation of the osteotomies and the repositioning of the bone fragments. A navigation module supports the surgeon during the execution of osteotomies and repositioning, as well as osteosynthesis. So far, the approach has been evaluated in laboratory trials and ex vivo tests.