J Korean Orthop Assoc.  2012 Dec;47(6):432-438. 10.4055/jkoa.2012.47.6.432.

Femoral Component Rotation of Total Knee Arthroplasty in Korean Subjects: A Study Using Grand Piano Sign and Computed Tomography

  • 1Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University, Cheongju, Korea. oseschoi@chungbuk.ac.kr


We aimed to obtain a reference for the optimal rotational alignment of femoral component in Koreans through an analysis of grand piano sign observed during total knee arthroplasty (TKA) and the angle between the clinical transepicondylar axis and the posterior condylar axis (TEA-PCA angle), by computed tomography.
The study subjects included 24 patients (30 cases), who underwent the anterior femoral resection, which was applied at an external rotation 3degrees relative to the posterior condylar axis during TKA. The relationship between anterior femoral resection with external rotation of 3degrees and the morphological pattern of Grand piano sign was evaluated. On postoperative computed tomography images, we evaluated the relationship between the clinical transepicondylar axis, posterior condylar axis of femoral component and grand piano sign. Moreover, a total of 28 Korean patients with 41 arthritic knees scheduled for a TKA had a preoperative computed tomography. We measured the TEA-PCA angle to evaluate the normal range in Korean subjects.
The morphological pattern of grand piano sign observed after the anterior femoral resection, which was applied at an external rotation 3degrees, showed statistically significant correlation with TEA-PCA angle. On preoperative computed tomography images, the TEA-PCA angle was 6.01 degrees (range from 3.90 to 7.86).
The TEA-PCA angle of Koreans was different from that of the westerners. More external rotation was needed for the optimal femoral rotational alignment theoretically, and we could confirm the correlation between Grand piano sign and rotational alignment of femoral component by measurement of grand piano sign and computed tomography.


grand piano sign; arthroplasty; replacement; knee
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