PubMed · 13978025
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K SOLHEIM. 1963-02-15. Larhalsbrudd.. https://pubmed.ncbi.nlm.nih.gov/13978025/
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Fluoroscopy-based navigation systems can be used for internal fixation of intracapsular femoral neck fractures, with the object of optimizing positioning of the implant and reducing radiation exposure. With this technique, the virtual position and direction of a reamer can be simultaneously superimposed on anteroposterior (AP) and axial (AX) fluoroscopic images. However, surgeons have to rely on the accuracy of these systems, because the only intraoperative feedback on the true position of the reamer is the projection of a virtual reamer superimposed on two fluoroscopic images. The objective of this study was to evaluate the accuracy of the displayed position of the virtual reamer in relation to the true position of the instrument when using a fluoroscopy-based navigation system (medivision, Oberdorf, Switzerland). Secondary to this, the accuracy of the drill-channel measuring tool of the system was analyzed. The study was performed on 20 sawbones. To evaluate the position of the virtual reamer, an 8-mm Perspex bar was inserted in predefined drill channels in each sawbone. AP and AX fluoroscopic images of the sawbones with the Perspex bar were loaded into the workstation. The Perspex bar was then removed and exchanged for a navigated dynamic hip screw (DHS) reamer. The position of the Perspex bar in the images represented the true position of the reamer. Subsequently, the difference between the position of the virtual reamer and the Perspex bar was measured with a dedicated computer program. Drill-channel lengths measured with the system were compared with measurements obtained with a digital ruler. The mean difference in position of the Perspex bar and reamer at a predefined point was 0.90 mm (range: 0.00-3.21 mm) in 360 images. The mean difference in length measurements between the medivision system and the digital ruler was 1.00 mm (p = 0.01, SD =1.33). Reaming and measuring the screw channel of a DHS with a medivision fluoroscopy-based navigation system can be performed with an acceptable error margin.
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Beside of modern surgical and implant techniques and basic pathophysiological knowledge, internal fixation of subcapsular fractures of the neck of the femur is still known to be connected with a high rate of complications. Implant failure, the typical early complication arising within the first 3 months, non-union, avascular necrosis of the femoral head and late segmental collapse are the typical complications. The type of fracture, timing of operation (emergency operation), quality of reduction and implant positioning have all been shown to predict outcome significantly. However, it is also suggested that further therapeutical interventions like intra-articular pressure decrease by evacuation of hematoma, the kind and technique of reduction, special surgical techniques and postoperative treatment can influence outcome, as well as patient-associated factors like age, degree of osteoporosis, neurological disease, and alcoholism. The superiority of one of the 100 different existing implants have not been proved either by clinical or by biomechanical trials. However, besides screw osteosynthesis, the sliding screw plate and less often sliding nail plate implants are commonly used. Because of the very different biomechanical principles it is of great importance to adhere to the special operative techniques to avoid intraoperative complications that might cause treatment failure. To reduce the frequency of these almost always fatal and in special circumstances lethal complications, we need some more detailed information from good clinical trials and sufficient external quality assurance.