Posterior condylar cartilage may distort rotational alignment of the femoral component based on posterior condylar axis in total knee arthroplasty

AbstractProper femoral component rotation in total knee arthroplasty (TKA) is important, given the prognostic impact of a poorly positioned component. The purpose of this observational study was to determine the incidence of femoral component malrotation using posterior condylar axis (PCA) referencing. A total of 100 knees in 92 patients with varus gonarthritis of the knee undergoing primary TKA using a standard medial parapatellar approach were evaluated intraoperatively. After distal femoral resection, the standard femoral sizing guide referencing the posterior condylar axis was used to set femoral component rotation. This was then compared with both the transepicondylar (TEA) and trochlear anteroposterior axes (TRAx). Disparites were recorded and corrected in line with the epicondylar axis. Rotational adjustment for addition of further external rotation was made in 13 (13.0%) cases. In seven cases, the medial pin sites were raised between 1 and 3 mm, and in six cases, the lateral pin site was lowered between 1 and 3 mm (based on risk of notching the femoral cortex). It is critical to not rely exclusively on the PCA to confirm rotational positioning of the femoral component as predicted by posterior condylar referencing guides. Intraoperative adjustment and confirmation using the TEA and TRAx occurred in 13% of primary TKA cases, which might have, otherwise, had a significant effect on the clinical outcome.

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ROTATIONAL ALIGNMENT OF THE FEMORAL COMPONENT IN TOTAL KNEE ARTHROPLASTY FOR VARUS OSTEOARTHRITIS OF THE KNEE; A RETROSPECTIVE STUDY

10.36106/ijar/4914205 ◽

2021 ◽

pp. 46-48

Author(s):

Pooyan Jalalpour ◽

Mohammadreza Minator Sajadi ◽

Seyed Amirali Matini ◽

Kamyar Makvandi

Keyword(s):

Total Knee Arthroplasty ◽

Retrospective Study ◽

Femoral Component ◽

Knee Arthroplasty ◽

External Rotation ◽

Rotational Alignment ◽

P Value ◽

Osteoarthritis Of The Knee ◽

Posterior Condylar ◽

Total Knee

Background and Aims: Achieving proper axial rotational alignment of the femoral component for varus knees is a critical step in total knee arthroplasty (TKA). Trans epicondylar axis (TEA) is the most reliable reference for alignment of femoral component. Yet, nding the exact location is sometimes difcult and time consuming. The aim of this study was to determine the correlation between the TEA and posterior condylar line reference (PCL) in varus knees. Besides, the other aim of this study was to nd the relationship between lateral distal femoral angle (LDFA) and femoral component external rotation (ER) measured intraoperatively. Material and Methods: This retrospective study was conducted on patients who were candidates for total knee arthroplasty from May 2016 to December 2019. LDFA, VA were calculated based on hip-to-ankle (HTA) radiographs before the surgery. All patients underwent TKA through an anterior midline incision. ER was calculated by determining TEA intraoperatively. All data were entered into SPSS software for data analysis. Results: One hundred and four patients were included in the nal analysis. Nineteen patients (18.3%) were male and 85 out of 104 (81.7%) were female. (P value = 0.001). No signicant relationship between the amount of ER measured during surgery and the amount of varus angle in varus knees was observed. Furthermore, there were no correlations between ER and LDFA in varus knees. Conclusion: Adjusting femoral component in 3 degrees external rotation relative to posterior condylar line reference achieves proper rotational alignment of the femoral component in the axial plane in varus knees. Also, the lateral distal femoral angle measured preoperatively from knee radiographs is not a predictor of ER in varus knees

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Effect of the presence of the articular cartilage on the femoral component rotation in total knee arthroplasty in female and varus osteoarthritis knees

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-020-02030-9 ◽

2020 ◽

Vol 15 (1) ◽

Author(s):

Ji-Hoon Nam ◽

Yong-Gon Koh ◽

Paul Shinil Kim ◽

Joon-Hee Park ◽

Kyoung-Tak Kang

Keyword(s):

Total Knee Arthroplasty ◽

Articular Cartilage ◽

Femoral Component ◽

Knee Arthroplasty ◽

Cartilage Thickness ◽

Condylar Cartilage ◽

Post Surgery ◽

Posterior Condylar ◽

Total Knee ◽

Male Patients

Abstract Purpose Surgical techniques for total knee arthroplasty (TKA) require femoral rotational corrections that alter the position of the surface of the posterior femoral joint especially in kinematic alignment. However, preoperative planning of TKA based on computed tomography (CT), without knowing the femoral cartilage thickness, may cause post-surgery failures in femoral rotation. Therefore, this study aimed to evaluate the effects of posterior condyle cartilage thickness on rotational alignment in the femoral component. Methods Three-dimensional magnetic resonance imaging (MRI) scans were obtained for 139 male and 531 female osteoarthritis patients. The angles defined by the femoral posterior condylar axis (PCA) and the surgical transepicondylar axis (TEA) were evaluated with respect to the presence of cartilage. Additionally, these effects were evaluated with respect to patient gender and varus/valgus condition. Results In all patients, the angle between the TEA and PCA was significantly greater in the presence of cartilage than in the absence of cartilage. This result was also seen in female patients. However, there was no difference in the TEA/PCA angle in male patients based on the presence of cartilage. The TEA/PCA angle was significantly greater in the presence of cartilage than in the absence of cartilage in the female varus group. However, there were no differences in the TEA/PCA angle based on the presence of cartilage in the male varus/valgus and female valgus groups. Cartilage thickness in the posterior femoral condyle was significantly greater on the lateral side than on the medial side in all and male patients. However, there was no difference between the genders regarding cartilage thickness. Conclusion Surgical planning for TKA based on CT does not consider articular cartilage and could lead to external malrotation of the femoral implant. Therefore, the effect of the remaining posterior condylar cartilage should be considered by surgeons to prevent over-rotation of the femoral component, especially in female varus knees.

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The posterior cortical axis as an alternative reference for femoral component placement in total knee arthroplasty

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-020-02146-y ◽

2020 ◽

Vol 15 (1) ◽

Author(s):

Ji-Hoon Nam ◽

Yong-Gon Koh ◽

Kiwon Kang ◽

Joon-Hee Park ◽

Kyoung-Tak Kang

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Rotational Alignment ◽

Transepicondylar Axis ◽

Femoral Geometry ◽

Posterior Condylar ◽

Total Knee ◽

Gender Based ◽

And Gender

Abstract Background Although several reference axes have been established for determining femoral rotational alignment during total knee arthroplasty (TKA), the most accurate axis is undetermined. This study determines the relationship between the posterior cortical axis (PCA) and the trochlear anterior line (TAL) of the femur in relation to the epicondylar axis. Methods A total of 341 patients who underwent TKA for osteoarthritis were enrolled. Patients who had undergone previous bony surgery or replacement that might have changed the femoral geometry were excluded. Finally, 336 patients (200 females and 136 males) were included in the study. The angles between the transepicondylar axis (TEA) and TAL and TEA and the femoral PCA (FPCA) were evaluated. We also assessed whether there was any significant differences in variance and gender in these two angles. Student’s t tests were used to determine the significance of coronal alignment and any gender-based differences. The variances between the TAL/TEA and FPCA/TEA angles were compared using F tests. Results The FPCA was externally rotated by 2.6° ± 3.6°, and the trochlear anterior line was internally rotated by 5.2° ± 5.5°, relative to the TEA. Gender-based differences were observed in the comparisons between anatomical references and TEA. Conclusions The FPCA is a more conservative landmark than the TAL for intraoperative or postoperative approximation of the TEA. When conventional reference axes, such as the posterior condylar axis and the anteroposterior axis, are inaccurate, surgeons can refer to this alternative reference. These findings demonstrate that the FPCA may be useful for determining the rotational alignment of the femoral component before and during TKA.

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