A comparative study on CT- and MRI-based patient specific matched guides (PSG) from the same manufacturer for the implantation of total knee arthroplasty (TKA) has not been undertaken. A total of 64 knees operated with CT based PSG was divided into two groups, with (n=32, CTHK) or without (n=32, CTNA) a history of a knee operation, and matched with a control group operated with MRI based PSG(n=64). Alignment of the biomechanical axis of the leg (HKA angle) and accuracy of individual implant alignment were measured on digital long-standing AP and sagittal radiographs. HKA and implant angles <3° deviation of the preoperative planned alignment were defined as correct. Peroperative implant size, OR time (min) and blood loss (ml) were compared. The average HKA angle in the CTHK group (177.0, 170.5 to 181.5, p=0.016) and mean varus-valgus alignment of the tibia component in the MRI group (90.6, 85.6 to 94.1, p=0.003) were statistically significant different. None of the outcome on the frontal femoral and lateral tibial component were statistically significant different. Percentage <3° deviation of the preoperative planned femoral flexion-extension alignment was better in the MRI group (84%, p=0.002), compared to the CTHK and CTNA group (respectively 30% and 42%). Average operation time was statistically significant shorter in favour of the MRI group (53.1, 34 to 80, p≤0.00), compared to the CTHK(70.8, 44 to 114) and CTNA group (59.2, 41 to 78). There is discrepancy between CT and MRI based PSG from the same manufacture because of patients who were not suitable for MRI due to history of a knee operation in the past. Whether these differences are clinically relevant is questionable. Future research needs to emphasise whether one of these two modalities, MRI or CT is superior compared to the other.
Patient-specific guiding (PSG) is a relatively new technique for aligning a total knee arthroplasty (TKA). Limited data exist on the precise accuracy of the technique. The purpose of this study is to investigate whether there was significant difference between the alignment of the individual femoral and tibial components (in all three anatomical planes) as calculated pre-operatively and the actually achieved alignment Twenty-six patients were included. Software permitted matching of the pre-operative MRI-scan (and therefore calculated prosthesis position) to a pre-operative full-leg CT-scan. After surgery a post-operative full-leg CT-scan could be superimposed onto the pre-operative CT-scan to accurately determine deviations from planning (see figure 1 and 2). This 3D-technique has an accuracy of 0.7–1.0 degrees.Background:
Methods:
The full leg x-ray is a widely used imaging modality for post-operative assessment of total knee replacement (TKR). However, these assessments require controlled conditions and precise measuring in order to be accurate. inter-observer reliability remains a matter of concern as well. This study examines whether intersurgeon differences are significant. Post-operative lateral and full-leg frontal x-rays of 26 patients were assessed by 6 surgeons according to a strict measuring protocol. Four measurements (Figure 1 and 2) were taken of which two were on the femur (Femoral Varus Angle FVA and Femoral Flexion Angle FFA) and two, on the tibia (Tibial Varus Angle TVA; Tibial Slope Angle TSA). A random effects, two-way ANOVA was performed on the data using Minitab (v 16.0, Minitab Inc., Pennsylvania, USA) to determine whether a surgeon has influence on the results (α = 0.05). Intra-class correlation coefficients (ICC) and standard error of measurements (SEM) resulting in smallest detectable changes (SDC) were also calculated [1].Background
Method
