CT anatomical features of the distal humerus in healthy adults

Objective To study the anatomical features of the distal humerus in Chinese healthy adults. Methods A total of 121 cases of normal elbow joint CT images were selected from the picture archiving and communication system (PACS), and reconstructed and measured on the AW4.5 workstation. Coronal plane and horizontal plane were determined by flexion-extension (FE) axis and humeral shaft, while the sagittal plane was perpendicular to the FE axis. The angle between the axis of humerus medullary cavity and the FE axis of elbow (H-FE angle) was measured on the coronal plane. The capitellar height (CH), lateral trochlear height (LTH), trochlear height (TH) and medial trochlear height (MTH) were measured on four different sagittal planes. The capitellar width (CW), capitellar depth (CD), anterior lateral trochlear width (ALTW), posterior lateral trochlear width (PLTW), trochlear width (TW), anterior medial trochlear width (AMTW), posterior medial trochlear width (PMTW), trochlear depth (TD), anterior lateral trochlear depth (ALTD), posterior lateral trochlear depth (PLTD), anterior medial trochlear depth (AMTD), posterior medial trochlear depth (PMTD), and distal humeral width (W) were measured on the horizontal plane. The gender differences in measured parameters, correlations between data, and differences in H-FE angle from 90° were analyzed. Results In male, CH was 21.5± 1.3 mm, CW 17.5±1.1 mm, CD 10.8±0.9 mm, TW 25.1±2.2 mm, TH 17.3±1.5 mm, TD 17.5±1.4 mm, ALTW 7.7±1.2 mm, PLTW 12.5±1.6 mm, AMTW 12.4±1.6 mm, PMTW 9.8±2.0 mm, ALTD 10.0±0.8 mm, PLTD 16.3±1.4 mm, AMTD 12.9±1.4 mm, PMTD 13.2±1.4 mm, LTH 20.6±1.3 mm, MTH 25.0±2.4 mm, W 42.6±2.5 mm. The above parameters in female was 18.7±1.1 mm, 15.3±1.1 mm, 9.5±0.6 mm, 21.7±1.5 mm, 15.4±1.7 mm, 15.6±1.5 mm, 6.8±1.3 mm, 10.7±1.4 mm, 10.6±1.4 mm, 8.5±1.4 mm, 8.9±0.8 mm, 14.5±1.1 mm, 11.4±1.1 mm, 11.5±1.0 mm, 18.1±1.4 mm, 21.6±1.4 mm and 37.0±1.8 mm, respectively. All the above anatomical parameters in men were larger than those in women with statistically significant difference (P 0.05). All measurements except for the H-FE angle had a positive correlation with the articular width (0.335≤r≤0.928, P<0.05). The difference between the angle of the H-FE axis (87.6°±3.4°) and 90° was statistically significant (t=-7.287, P<0.05). Conclusion The size of the distal humerus in male is larger than that in female without difference in shape. Distal humerus width can be used as an indicator to measure the size of the distal humerus. The humeral shaft is more biased toward the radial side. Key words: Humerus; Arthroplasty, replacement, elbow; Prosthesis design; Morphology; Tomography, X-ray computed