Usefulness of the “grand-piano sign” for determining femoral rotational alignment in total knee arthroplasty

Ohmori, Takaaki; Kabata, Tamon; Kajino, Yoshitomo; Taga, Tadashi; Inoue, Dai; Yamamoto, Takashi; Takagi, Tomoharu; Yoshitani, Junya; Ueno, Takuro; Tsuchiya, Hiroyuki

doi:10.1016/j.knee.2017.11.008

Cited by 9 publications

(23 citation statements)

References 26 publications

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“…Thus, there might be substantial differences in the vertical length and the ratio of the anterior resection surface according to the distal femoral resection, which would be more frequent in clinical practice. In a study by Ohmori et al 19) , the MD/LD ratio after distal femoral resection was 0.62 to 0.67, but the ratio increased with the increase in exion angle of the distal femoral resection.…”

Section: Discussionmentioning

confidence: 90%

“…[16][17][18][19] The asymmetrical shape of the anterior resection surface of the femur, the so-called "grand-piano sign," was considered a reference for the correct rotational angle of the femoral condylar resection when aligned parallel with TEA. [16][17][18][19] However, the shape of the anterior resection surface is known to change with the femoral rotation angle, [17][18][19] distal femoral resection parameters, 18,19) and even kinematic aligned TKA. 18) Cui et al 17) have reported that the MD/LD ratio of the anterior resection surface was 0.66 and 0.69 when using the surgical TEA and 3° external rotation relative to the posterior condylar axis, respectively, by measuring the vertical distance without considering the distal femoral resection.…”

Section: Discussionmentioning

confidence: 99%

“…[12][13][14][15] The shape of the anterior resected surface of the femur, the so-called "grand-piano sign," has also been used as a landmark to assess the correct rotational alignment during TKA. [15][16][17][18][19] Previous simulated anatomical studies have reported morphologic patterns of the anterior femoral condylar resection surface as a reliable intraoperative reference to assess femoral rotational alignment in TKA. [17][18][19] In a previous study, those morphologies were de ned using the ratio of the medial and lateral anterior femoral resection surfaces, typically 0.65 to 0.69 as the "grand-piano sign," 0.5 to 0.55 as the "boot sign," and 0.8 to 0.98 as the "butter y sign."…”

Section: Introductionmentioning

confidence: 99%

“…[15][16][17][18][19] Previous simulated anatomical studies have reported morphologic patterns of the anterior femoral condylar resection surface as a reliable intraoperative reference to assess femoral rotational alignment in TKA. [17][18][19] In a previous study, those morphologies were de ned using the ratio of the medial and lateral anterior femoral resection surfaces, typically 0.65 to 0.69 as the "grand-piano sign," 0.5 to 0.55 as the "boot sign," and 0.8 to 0.98 as the "butter y sign." 17) However, only a few simulation studies have reported the shape of the femoral anterior cutting plane using computed tomography (CT) or cadaver.…”

Section: Introductionmentioning

confidence: 99%

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“Boot Sign” of Anterior Femoral Condylar Resectional Shape during Total Knee Arthroplasty is more frequent in Asian Patients

Kim

Park

Baek

et al. 2022

Preprint

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Purpose There is lack of intraoperative consensus on the distal femur anterior resected surface shape that allows reliable rotational alignment assessment during total knee arthroplasty (TKA). We aimed to evaluate the ratio and prevalence of anterior femoral resection surface intraoperatively. Materials and Methods The study included 234 osteoarthritis patients with varus knees and not valgus knees or deformities. The anteroposterior (AP) lengths after distal femoral resection were measured as the femoral lateral AP (FLAP) and femoral medial AP (FMAP) lengths. Based on the medial (MD) and lateral condyle (LD) vertical distance ratios of the femur anterior resected surface, the groups were classified into “boot sign”, “grand-piano”, and “butterfly sign” groups. Linear regression analyses were used to find the associated factors to the anterior femoral resection surface shape. Results Mean intraoperative femoral rotation and distal femoral cutting angles were 4.9° ± 1.2 and valgus 5.0° ± 0.7, respectively. Mean FLAP was 52.9 ± 4.2 mm. Mean MD/LD (0.61 ± 0.13) was lower than that of typical “grand-piano sign”. The morphological shape incidence of ‘boot sign’ was 62.4%. The MD/LD-associated factors were FLAP, intraoperative femoral rotation and distal femoral cutting angles. (R2 = 0.268) Conclusion The femur anterior resection surface shape in TKA was found in the “boot sign” rather than the “grand-piano sign” in Korean ethnics owing to an asymmetric morphology of femoral condyles. Ethnic differences, including distal femoral morphology, should be considered for assessment of the femoral rotation angle using the femur anterior resection surface shape.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

“Boot Sign” of Anterior Femoral Condylar Resectional Shape during Total Knee Arthroplasty is more frequent in Asian Patients

Kim

Park

Baek

et al. 2022

Preprint

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“…Grand piano sign, the femoral anterior tangent (FAT) line, and trochlear line are other reference axes focused on the shape of the cutting plane. 20,[28][29][30] Alternatively, there is a method of outputting the SEA projected on a bone-cutting plane on CT, copying it to a sheet, and drawing a line for use during surgery. 31 As described above, there are various methods for reproducing the SEA based on past reports, but what more important is accurately getting the SEA.…”

Section: Discussionmentioning

confidence: 99%

Importance of Three-Dimensional Evaluation of Surgical Transepicondylar Axis in Total Knee Arthroplasty

et al. 2020

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In total knee arthroplasty, the surgical transepicondylar axis (SEA) is one of the most reliable rotation axes for stabilizing of the patellofemoral joint. The SEA is identified with reference to the lateral epicondyle and the medial sulcus of the medial epicondyle. However, these two structures rarely appear on the same plane on computed tomography (CT), and it is necessary to take two points in separate images. Many surgeons measure the SEA on the same image (pseudo SEA) instead. We aimed to determine the difference between true SEAs and pseudo SEAs. A total of 31 normal knees and 24 varus knees were included in this study. Three-dimensional (3D) models of the femur were reconstructed from CT images, and a reconstructed plane was made using the International Society of Biomechanics coordinate system. Pseudo SEAs drawn in the plane passing through the lateral epicondyle and medial sulcus were defined as l-SEA and m-SEA, respectively. L-SEA, m-SEA, true SEA, and posterior condylar axis (PCA) were projected onto the International Society of Biomechanics coordinate plane and, “p l-SEA,” “p m-SEA,” “p true SEA,” and “p PCA” were obtained. The true SEA angle was defined as the angle between p true SEA and p PCA. The l-SEA angle or m-SEA angle was defined as the angle between the p l-SEA or p m-SEA and p PCA, respectively. There were no statistically significant differences between true SEA angle (2.64 ± 2.01 degrees) and pseudo SEA angle (l-SEA angle: 2.74 ± 2.07 degrees, m-SEA: 2.54 ± 2.19 degrees). Conversely, 12 knees in the normal group and 2 knees in the varus group had differences of more than 1 degree (p = 0.01). Among them, 6 knees in the normal group and 0 knees in the varus group had a difference of 2 degrees or more (p = 0.03). In most cases, pseudo SEA can be substituted for true SEA.

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Revision of unicompartmental knee arthroplasty using the in situ referencing technique

Weißenberger

Petersen

Bölch

et al. 2020

Oper Orthop Traumatol

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Usefulness of the “grand-piano sign” for determining femoral rotational alignment in total knee arthroplasty

Cited by 9 publications

References 26 publications

“Boot Sign” of Anterior Femoral Condylar Resectional Shape during Total Knee Arthroplasty is more frequent in Asian Patients

“Boot Sign” of Anterior Femoral Condylar Resectional Shape during Total Knee Arthroplasty is more frequent in Asian Patients

Importance of Three-Dimensional Evaluation of Surgical Transepicondylar Axis in Total Knee Arthroplasty

Revision of unicompartmental knee arthroplasty using the in situ referencing technique

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