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

Accuracy and reproducibility of two-dimensional computed tomography-based positioning of femoral component rotational alignment in preoperative planning for total knee arthroplasty

BACKGROUND

Poor rotation of the femoral component in total knee arthroplasty (TKA) can result in various postoperative complications, underscoring the critical importance of preoperative planning.

PURPOSE

To improve the accuracy of femoral component positioning during TKA, this study compared the accuracy and repeatability of different two-dimensional (2D) computed tomography (CT) measurement methods for measuring the posterior condylar angle (PCA) in preoperative TKA planning.

METHODS

A retrospective analysis was conducted on 75 patients (150 knees) who underwent bilateral lower extremity computed tomography angiography (CTA) at Fuyang People's Hospital from January 2021 to July 2021. Three different methods were used to measure the PCA based on 2D CT images (axial CT slices) and three-dimensional(3D) models (femoral models reconstructed from CT data) in this study. Method 1: Single-plane 2D CT measurement, measuring PCA in the most obvious single-plane CT slice of the surgical transepicondylar axis (sTEA); Method 2: multi-plane 2D CT measurement, identifying and locating anatomical landmarks in multiple 2D CT slices and measuring PCA; Method 3: 3D model measurement, measuring PCA in the reconstructed femur 3D model. Compare the differences in PCA measurements between the three measurement methods. A positive PCA measurement was recorded when the sTEA was externally rotated relative to the posterior condylar line (PCL). Any difference exceeding 3° between the PCA measurement in the 2D CT and the PCA reference value in the 3D model was classified as an outlier. The intraclass correlation coefficient (ICC) and Bland-Altman method were utilized to assess the intra- and inter-observer reproducibility of the three measurement methods.

RESULTS

The PCA measurement in the single-plane 2D CT was 1.91 ± 1.94°, with a measurement error of - 1.22 ± 1.32° and 12.7% of outlier values. In the multi-plane 2D CT, the PCA measurement was 2.96 ± 1.68°, with a measurement error of -0.15 ± 0.91° and 6.0% of outlier values. The PCA measurement in the 3D model was 3.12 ± 1.69°. The PCA measurement in single-plane 2D CT was notably smaller than that in multi-plane 2D CT and 3D models, with no significant difference between the latter two. The multi-plane 2D CT showed significantly lower measurement error and outlier values than the single-plane 2D CT. All three PCA measurement methods exhibited high reproducibility (ICC: 0.93 ~ 0.97).

CONCLUSIONS

Using of multi-plane 2D CT for measuring PCA in preoperative planning of TKA has high reproducibility and accuracy, with fewer outlier values. We recommend preoperative measurement of PCA using muti-plane 2D CT to improve the accuracy of positioning the femoral component rotational alignment during surgery.

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

BACKGROUND

There are many reference axes to determine the rotational positioning of the femoral prosthesis in total knee arthroplasty (TKA), mainly including the surgical transepicondylar axis (sTEA), anatomical transepicondylar axis (aTEA), Whiteside line, and the posterior condylar line (PCL), etc., but there is still no definite conclusion on which is the most accurate reference axis.

OBJECTIVE

To explore the reproducibility of each reference axis of femoral external osteotomy based on the 3D CT femoral model, compare the deviation of the simulated femoral prosthesis rotation alignment, positioned based on each reference axis, with the gold standard sTEA, and analyze the accuracy of each reference axis.

METHODS

The imaging data of 120 patients with knee osteoarthritis who underwent a 3D CT examination of the knee in our hospital from June 2018 to December 2021 were retrospectively collected. The 3D model of the femur was established by Mimics software. The line relative to PCL externally rotated 3° (PCL + 3°), aTEA, and the vertical line of the Whiteside line were constructed and compared with the gold standard sTEA. Intra-observer, as well as inter-observer reproducibility analysis, was performed by the intra-group correlation coefficient (ICC) and Bland-Altman method.

RESULTS

The angle ∠WS, between the vertical line of Whiteside and sTEA, was 2.54 ± 2.30°, with an outlier of 54.2%; the angle ∠aTEA, between aTEA and sTEA, was 4.21 ± 1.01°, with an outlier of 99.1%; the angle ∠PCL, between PCL + 3° external rotation and sTEA, was 0.50 ± 1.06°, with the highest accuracy and an outlier of 5.8%, and the differences among all three were statistically significant, P < 0.05. The intra-observer ICC values of ∠WS, ∠aTEA, and ∠PCL were 0.975 (0.964-0.982), 0.926 (0.896-0.948), and 0.924(0.892,0.946), respectively, and the reproducibility levels were excellent; the inter-observer ICC values of ∠WS, ∠aTEA, and ∠PCL were 0.968(0.955-0.978), 0.906 (0.868-0.934) and 0.970 (0.957,0.979), respectively, with excellent reproducibility levels; Bland-Altman plots suggested that the scatter points of intra-observer and inter-observer measurement differences more than 95% were within the limits of agreement.

CONCLUSION

The reference axis for locating the distal femoral external rotation osteotomy based on the 3D CT femoral model has good reproducibility. The PCL is easy to operate, has the highest precision, and the lowest outliers among the reference axes is therefore recommended.

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

Background and objectives: The introduction of novel techniques in total knee arthroplasty (TKA) aiming to enhance outcomes and satisfaction of the procedure is constantly ongoing. In order to evidence a priority of one, we have conducted a randomized controlled trial with the aim of comparing patient-reported functional outcomes, radiographic outcomes and intraoperative measures between imageless (NAVIO and CORI), robotic-assisted (ra)- TKA (ra-TKA) and manual TKA (mTKA) for primary knee osteoarthritis (KOA). Materials and Methods: A total of 215 patients with the diagnosis of KOA of the knee were randomly assigned to one of the three groups: NAVIO (76 patients) or CORI (71 patients) robotic-assisted TKA, or manual technique (68 patients) TKA. The primary outcome (Knee Injury and Osteoarthritis Outcome Study [KOOS]), Visual Analogue Scale (VAS), Range of motion (ROM), femoral component rotational alignment and the secondary outcomes (surgery time, blood loss, complications, and revision at 12 months after surgery) were compared between three groups. KOOS and VAS were collected at particular follow up visits from each patient individually and ROM in flexion and extension was assessed during the physical examination. Femoral component rotational alignment was measured on the CT scan performed postoperatively utilizing the Berger's method. Statistical significance was set at p < 0.05. Results: Both the ra-TKA groups and mTKA group displayed significant improvements in the majority of the functional outcome scores at 12 months. Despite having more prominent surgery time (NAVIO: mean +44.5 min in comparison to mTKA and CORI: mean +38.5 min in comparison to mTKA), both NAVIO and CORI tend to achieve highly accurate femoral component rotational alignment with mean radiographic scores in NAVIO vs. CORI vs. mTKA of 1.48° vs. 1.33° vs. 3.15° and lower blood loss (NAVIO: 1.74; CORI: 1.51; mTKA: 2.32. Furthermore, the investigation revealed the significant difference in femoral component rotational alignment between mTKA-NAVIO and mTKA-CORI and significantly different KOOS scores in NAVIO vs. CORI vs. mTKA of 87.05 vs. 85.59 vs. 81.76. Furthermore, the KOOS analysis showed between group significant statistical differences, but did not reach minimal clinically significant difference. There were no differences in postoperative ROM and VAS. There were no differences in complications between groups. Conclusions: To achieve a successful TKA, the precise tool and individualised objective is of great importance. The results suggest satisfactory results after both ra-TKA methods and mTKA. Ra-TKA and mTKA stand for a safe and reliable treatment method for OA. Patients reported excellent alleviation in functional outcomes and the radiological results revealed that the better precision does not necessarily lead to a better outcome. Therefore, ra-TKA does not imply strong enough advantages in comparison to the manual method, especially in terms of cost-efficiency and surgical time.