A comparison of femoral component rotation after total knee arthroplasty in Kanekasu radiographs, axial CT slices and 3D reconstructed images

Abstract

Objective To compare the posterior condylar angle measured with Kanekasu radiograph and 2D-CT with the gold standard 3D-CT following primary total knee arthroplasty (TKA). Methods Eighty-two knees with pain following TKA were included in this retrospective study. Two independent raters measured the anatomical and surgical posterior condylar angles twice on each Kanekasu radiograph and 2D-CT. These measurements were compared against the 3D-CT measurement. The intra- and interrater reliability of the Kanekasu radiograph and 2D-CT and the correlation with 3D-CT were calculated. Results The intra- and interrater reliability for measurements of the anatomical posterior condyle angle for the Kanekasu radiograph and the 2D-CT were excellent for both raters (0.85–0.92). For the less experienced rater 1, the intrarater reliability was significantly better for 2D-CT than Kanekasu radiograph for measuring both the surgical (p < 0.01) and anatomical posterior condyle angles (p < 0.05). For the experienced rater 2, the intrarater reliability was significantly better for Kanekasu radiograph than 2D-CT for measurement of the surgical posterior condyle angle (p < 0.05). The correlation with 3D-CT is higher in 2D-CT than in Kanekasu radiograph (p < 0.01). While the Kanekasu radiograph predicts the 3D-CT angle with 65.9%, 2D-CT can measure the true angle with 82.9% certainty. Conclusion Measurements using the anatomical transepicondylar axis are easier to replicate compared to the surgical transepicondylar axis. In comparison with the gold standard 3D-CT, 2D-CT showed a significantly higher correlation with 3D-CT than the Kanekasu measurements. If 3D-CT is available, it should be preferred over 2D-CT and Kanekasu view radiograph for femoral component rotation measurements.

Robotic-Assisted Total Knee Arthroplasty Utilizing NAVIO, CORI Imageless Systems and Manual TKA Accurately Restore Femoral Rotational Alignment and Yield Satisfactory Clinical Outcomes: A Randomized Controlled Trial

“…If the reference on lateral condyle is unique on the apex of bony prominence, there are two possible references for the medial condyle: The apex of the medial prominence defines the anatomical TEA (A TEA); and the surgical TEA (S TEA) connects the lateral condyle and the medial sulcus on the femur. The chose A TEA, which was made according to Robertson et al conclusions, that is, the measurements using the A TEA transepicondylar axis are easier to replicate compared to the S TEA axis [ 34 ].…”

Accuracy and reproducibility analysis of different reference axes for femoral prosthesis rotation alignment in TKA based on 3D CT femoral model

“…Our results are consistent with the results reported by Lei et al [ 10 ], who positioned and measured the deviation of the Whiteside line and the PCL positioned femoral prosthesis rotational alignment from sTEA in a reconstructed 3D CT model of the femur, with intra- and inter-observer ICC > 0.9, with good reproducibility. The results of the study conducted by Robertson et al [ 22 ] also indicated that compared to 2D CT, the accuracy and repeatability of locating reference axes were higher in 3D CT models. However, many studies [ 10 , 23 ] have performed CT scans of the entire femur to locate the mechanical axis of the femur in the 3D model, which can increase the exposure time to radiation and additional financial burden.…”

“…But their included were all normal femora, and the included femora in this study were all KL grade II and above, so this study was closer to clinical reality, and the conclusions were more reliable. However, many studies that consider performing routine external rotation 3° osteotomy on patients do not take into account the anatomical variation of the distal femur [ 22 , 32 ], the asymmetric wear, varus deformity, etc., which can make PCA individualized [ 33 ], and routine external rotation 3° osteotomy is not accurate. In a cadaveric study, Mantass et al [ 34 ] reported that the sTEA relative to PCL external rotation angle ranged from − 1° to 7°, with a mean external rotation of 5°.…”

“…They considered that this was associated with wear of the posterior lateral femoral cartilage, leading to an increase in PCA at the time of measurement. The reasons for this may be related to differences in the anatomy of the distal femur in different ethnic groups and people with different characteristics [ 35 , 37 ], in addition to the fact that different measurement methods may have an impact on the results [ 22 ]. In our opinion, although the deviation of PCL + 3° external rotation from sTEA has clear outliers, it is accurate in most cases.…”