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Factors affecting femoral rotational angle based on the posterior condylar axis in gap-based navigation-assisted total knee arthroplasty for valgus knee.

ABSTRACT: BACKGROUND:Achieving proper rotational alignment of the femoral component in total knee arthroplasty (TKA) for valgus knee is challenging because of lateral condylar hypoplasia and lateral cartilage erosion. Gap-based navigation-assisted TKA enables surgeons to determine the angle of femoral component rotation (FCR) based on the posterior condylar axis. This study evaluated the possible factors that affect the rotational alignment of the femoral component based on the posterior condylar axis. MATERIALS AND METHODS:Between 2008 and 2016, 28 knees were enrolled. The dependent variable for this study was FCR based on the posterior condylar axis, which was obtained from the navigation system archives. Multiple regression analysis was conducted to identify factors that might predict FCR, including body mass index (BMI), Kellgren-Lawrence grade (K-L grade), lateral distal femoral angles obtained from the navigation system and radiographs (NaviLDFA, XrayLDFA), hip-knee-ankle (HKA) axis, lateral gap under varus stress (LGVS), medial gap under valgus stress (MGVS), and side-to-side difference (STSD, MGVS - LGVS). RESULTS:The mean FCR was 6.1° ± 2.0°. Of all the potentially predictive factors evaluated in this study, only NaviLDFA (? = -0.668) and XrayLDFA (? = -0.714) predicted significantly FCR. CONCLUSIONS:The LDFAs, as determined using radiographs and the navigation system, were both predictive of the rotational alignment of the femoral component based on the posterior condylar axis in gap-based TKA for valgus knee. A 1° increment with NaviLDFA led to a 0.668° decrement in FCR, and a 1° increment with XrayLDFA led to a 0.714° decrement. This suggests that symmetrical lateral condylar hypoplasia of the posterior and distal side occurs in lateral compartment end-stage osteoarthritis with valgus deformity.

SUBMITTER: Lee SS

PROVIDER: S-EPMC5953479 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Factors affecting femoral rotational angle based on the posterior condylar axis in gap-based navigation-assisted total knee arthroplasty for valgus knee.

Lee Sung-Sahn SS Lee Yong-In YI Kim Dong-Uk DU Lee Dae-Hee DH Moon Young-Wan YW

PloS one 20180515 5

<h4>Background</h4>Achieving proper rotational alignment of the femoral component in total knee arthroplasty (TKA) for valgus knee is challenging because of lateral condylar hypoplasia and lateral cartilage erosion. Gap-based navigation-assisted TKA enables surgeons to determine the angle of femoral component rotation (FCR) based on the posterior condylar axis. This study evaluated the possible factors that affect the rotational alignment of the femoral component based on the posterior condylar ...[more]

PMID: 29763429

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Project description:Background Preoperative deformity and hinge position are associated with the magnitude of the gap opening during corrective osteotomy. A larger opening gap angle is associated with a higher risk of complications. This cross-sectional study sought to identify a suitable hinge position that results in the smallest opening angle during tibial condylar valgus osteotomy (TCVO). Methods The data of 66 arthritic knees treated by TCVO were included, comprising 16 knees with the hinge points selected medial to the center (group M), 21 knees with the hinge points selected at the center (group C), and 29 knees with the hinge points selected lateral to the center of the intercondylar eminence (group L). The opening gap angles and the correction amounts of the medial proximal tibial angle (ΔMPTA) were compared among the 3 groups to identify the preliminary relationship between the hinge positions and the opening gap angle. A simplified geometric model with the hinge positions selected at the medial beak, the center, and the lateral beak of the intercondylar eminence was constructed to simulate the realignment process. Several anatomical points were allocated as Cartesian coordinates. The opening gap angle with different hinge positions was mathematically formulated with MATLAB (MathWorks, Natick, MA, USA). Results The average ΔMPTAs were 9.4±2.9°, 9.4±3.5°, and 9.3±3.0° in groups L, C, and M, respectively. The opening angle of the osteotomy gap was the largest in group M and the smallest in group L (29.7±11.1° and 16.9±5.3°; P<0.01). The comparison of the opening angle per the ΔMPTA revealed a similar pattern. The simulated realignment process indicated that the hinge point at the lateral beak of the intercondylar eminence led to the smallest opening angle. The opening angle during TCVO was mathematically derived in terms of the ΔMPTA, the position of the intersection of the pre- and postoperative joint lines, and the position of the hinge point. Conclusions The hinge point at the lateral beak of the intercondylar eminence results in the smallest opening angle and may be suitable for TCVO.

Project description:Introduction:Recently, some studies showed assessment of the component gap is important for determination of the implant-inserted condition during total knee arthroplasty (TKA). We perform the modified gap technique with adjustment of the virtual gap which estimated by computer-aided design (CAD) using navigation system. The purpose of this study was to compare the virtual gap (CAD-gap) with the actual gap after inserting a femoral trial component (Trial-gap), and examine the usefulness of the surgical technique. Materials and methods:The subjects were 35 patients who underwent primary TKA using a navigation system and posterior-stabilized type TKA. The surgical procedure was to produce an extension gap, confirm the flexed CAD-gap on the navigation screen based on CAD data, and plan osteotomy of the femur. After osteotomy, the femoral component was inserted and the gap balance was measured. A tensor was used to adjust and measure the gap balance. Initial alignment, rotation of the femoral component, soft tissue balance in extension, final alignment after fixing all components, and the CAD- and Trial-gaps in both extension and flexion were evaluated. Results:The mean initial alignment angle, rotation angle of the femoral component, soft tissue balance angle and final alignment angle were 8.1 ± 4.2° varus, 3.5 ± 1.3°external rotation, 2.7 ± 2.5° varus and 0.4 ± 1.4° varus respectively. The mean medial and lateral CAD-gaps in extension were 10.8 ± 2.5 and 13.7 ± 2.5 mm, and the mean medial and lateral CAD-gaps in flexion were 12.2 ± 2.2 and 13.9 ± 2.7 mm. The equivalent Trial-gaps in extension and flexion were 10.5 ± 2.6 and 11.4 ± 3.1 mm, and 12.2 ± 2.5 and 14.4 ± 2.8 mm. The CAD- and Trial-gaps differed significantly only for lateral gaps in extension. Conclusion:In comparing the CAD-gap and the Trial-gap, only small difference was found in the lateral gap of extension. The other gaps in both extension and flexion were well maintained. We concluded adjustment of the CAD-gap during surgery using a navigation system can be used to adjust the actual component gap especially in the medial side.

Dataset Information

Factors affecting femoral rotational angle based on the posterior condylar axis in gap-based navigation-assisted total knee arthroplasty for valgus knee.

Publications

Factors affecting femoral rotational angle based on the posterior condylar axis in gap-based navigation-assisted total knee arthroplasty for valgus knee.

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