Hip and knee joint replacement is nowadays one of the most common surgeries in Germany. The frequency of peri- and post-operative complications varies depending on the study. Since 2001, every hospital in Germany is required to report any peri- and post-operative complication to an external institute for quality control. The purpose of this study was to evaluate the published data of these institutes and to differentiate between the rate of peri- and early postoperative complications of conventional and computer navigated surgical procedures. The hypothesis of the study was that there is no increase in the rate of peri- and early post-operative complications as a result of the navigated surgical procedure. A retrospective analysis of the data on primary total knee and hip replacements between 2004 and 2012 were conducted. The share of navigated procedures, additional operating time due to navigation, the peri- and early post-operative surgical and general rates of complications and the comparison of patient population (age, sex and ASA-classification) were subject of the analysis.Introduction
Materials and Methods
Digital planning of implants in regard to position and size is done preoperatively in most cases. Intraoperative it can only be made by navigation systems. With the development of the VIPS-method (Virtual Implant Planning System) as an application for mobile C-arms, it is possible to do an intraoperative virtual planning of the screws near the joint in treatment of distal radius fractures by plating. Screw misplacement is a well known complication in the operative treatment of these fractures. The aim of this prospective randomised trial was to gain first clinical experiences and to compare VIPS with the conventional technique. The study hypothesis was that there will be less screw misplacement in the VIPS group. We included 40 patients with distal radius fractures type A3, C1 and C2 according to the AO-classification. In a pilot study the first 10 Patients were treated by the VIPS method to gain experience with VIPS in a clinical set-up. The results of the pilot-study are not part of this analysis. Then 15 Patients were web-based randomised into two groups. After diaphysial fixation of a 2.4 mm Variable Angle Two-Column Volar Distal Radius Plate and fracture reduction matching of a three-dimensional virtual plate to the two-dimensional image of the plate in the fluoroscopy shots in two plains was performed automatically in the VIPS group. The variable angle locking screws were planed in means of direction and length. Drilling was done by the use of the Universal Variable Angle Locking Drill Guide that was modified by laser marks at the rim of the cone to transfer the virtual planning. The drill guide enables drilling in a cone of 30°. In the control group the same implant was used in a conventional technique that means screw placement by the surgeon without digital planning. After implant placement an intraoperative three-dimensional scan was performed to check the position and length of the screws near the joint. OR- and fluoroscopy-time was documented. In addition the changes of misplaced screws were engaged.Background
Methods
The goal of this study was to validate accuracy and reproducibility of a new 2D/3D reconstruction-based program called “HipRecon” for determining cup orientation after THA. “HipRecon” uses a statistical shape model based 2D/3D deformable registration technique that can reconstruct a patient-specific 3D model from a single standard AP pelvic X-ray radiograph. Required inputs include a digital radiograph, the pixel size, and the film-to-source distance. No specific calibration of the X-ray, or a CAD (computer-assisted design) model of the implant, or a CT-scan of the patient is required. Cup orientation is then calculated with respect to the anterior pelvic plane that is derived from the reconstructed 3D-model. The validation study was conducted on datasets of 29 patients (31 hips). Among them, there were 15 males and 14 females. Each dataset has one post-operative X-ray radiograph and one post-operative CT-scan. The post-operative CT scan for each patient was used to establish the ground truth for the cup orientation. Radiographs with deep centering (7 radiographs), or of pelvises with fractures (2 radiographs), or with both (1 radiograph), or of non-hemispherely shaped cup (1 radiograph) were assessed separately from the radiographs without above mentioned phenomena (18 radiographs) to estimate a potential influence on the 2D/3D reconstruction accuracy. To make the description easier, we denote those radiographs with above mentioned phenomena as non-normal cases and those without as normal cases. The cup anteversions and inclinations that were calculated by “HipRecon” were compared to the associated ground truth. To validate the reproducibility and the reliability, one observer conducted twice measurements for each dataset using “HipRecon”. The mean accuracy for the normal cases was 0.4° ± 1.8° (−2.6° to 3.3°) for inclination and 0.6° ± 1.5° (−2.0° to 3.9°) for anteversion, and the mean accuracy for the non-normal cases was 2.3° ± 2.4° (−2.1° to 6.3°) for inclination and 0.1° ± 2.8° (−4.6° to 5.1°) for anteversion. Comparing the measurement from the normal radiographs to those from the non-normal radiographs using the Mann-Whitney U-test, we found a significant difference in measuring cup inclination (p = 0.01) but not in measuring cup anteversion (p = 0.3). Bland-Altman analysis of those measurements from the normal cases indicated that no systematical error was detected for “HipRecon,” as the mean of the measurement pairs were spread evenly and randomly for both inclination and anteversion. “HipRecon” showed a very good reproducibility for both parameters with an intraclass correlation coefficient (ICC) for inclination of 0.98 (95% Confidence Limits (CL): 0.96–0.99) and for anteversion of 0.96 (95% CL: 0.91–0.98). Accurate assessment of the acetabular cup orientation is important for evaluation of outcome after THA, but the inability to measure acetabular cup orientation accurately limits one's ability to determine optimal cup orientations, to assess new treatment methods of improving acetabular cup orientation in surgery, and to correlate the acetabular cup orientation to osteolysis, wear, and instability. In this study, we showed that “HipRecon” was an accurate, consistent, and reproducible technique to measure cup orientation from post-operative X-ray radiographs. Furthermore, our experimental results indicated that the best results were achieved with the radiographs of non-fractured pelvises that included the anterior superior iliac spines and the cranial part of the non-fractured pelvis. Thus, it is recommended that these landmarks should be included in the radiograph whenever the 2D/3D reconstruction-based method will be used
