The relationship between the midpoints connecting the tibial attachments of the anterior and posterior cruciate ligaments and the transepicondylar axis: In vivo three-dimensional measurement in the Chinese population

BackgroundTo determine the relationship between the midpoints connecting the tibial attachments of the anterior and posterior cruciate ligament (ACL and PCL, APCL line) and the transepicondylar axis (TEA) in normal healthy Chinese, as well as the comparison with other rotational lines.MethodsLeft knees of 17 male and 15 female healthy Chinese volunteers were scanned by magnetic resonance imaging (MRI) and computer tomography (CT) respectively. 3D contours of each knee, the tibial attachments of ACL, PCL, the medial and lateral collateral ligaments were reconstructed separately from CT and MRI data. Using an iterative closest point algorithm, we superimposed them individually. The APCL line, the tibial posterior condylar line (PC line), the medial third of the tibial tubercle (1/3 line), the Akagi's line, and the midsulcus of the tibial spine (Midsulcus line), the clinical and surgical TEA (CTEA and STEA) were determined. The paired intersection angles of them were measured.ResultsThe mean angle CTEA with APCL line, Akagi's line, Midsulcus line, 1/3 line, and PC line, respectively, was 90.3° ± 2.9°, 95.0°±3.0°, 94.0° ± 3.9°, 102.4° ± 2.7°, and 87.1° ± 3.0°. The APCL–CTEA was significant different than other angles (p < 0.001). The mean angle STEA to the above lines, respectively, was 94.8° ± 3.1°, 99.4° ± 3.1°, 98.5° ± 4.0°, 106.9° ± 2.9°, and 91.6° ± 3.2°. The PC line-STEA was significantly different than other angles (p < 0.05).ConclusionsAPCL line was the closest perpendicular to the CTEA in normal Chinese subjects comparing with other rotational lines.