Ultrasound-assisted measurement of humeral version: a radiation-sparing alternative to whole-humerus computed tomography

Article information

Clin Shoulder Elb. 2025;28(3):266-273

Publication date (electronic) : 2025 September 1

doi : https://doi.org/10.5397/cise.2025.00913

Hee Dong Lee¹, Yun Seong Choi¹, Woo Seung Lee¹, Jung Taek Im², Jae Chul Yoo^,3

¹Department of Orthopedic Surgery, Veterans Health Service Medical Center, Seoul, Korea

²Suwon Soo Hospital, Suwon, Korea

³Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

Corresponding Author: Jae Chul Yoo Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea Tel: +82-2-3410-3501, Fax: +82-2-3410-0061 Email: shoulderyoo@gmail.com

Received 2025 July 21; Revised 2025 July 29; Accepted 2025 August 1.

Abstract

INTRODUCTION

Humeral version refers to the angle at which the distal humerus is oriented relative to the proximal humerus. Accurate measurement of humeral version is crucial for preoperative planning in reverse total shoulder arthroplasty (RTSA) [1,2]. Computed tomography (CT) is the gold standard for humeral version measurement, and requires full-length humerus imaging, while standard preoperative planning for shoulder arthroplasty typically involves a CT scan that includes only the scapula and proximal humerus [3]. Consequently, an additional CT scan of the entire humerus is required solely for humeral version measurement, increasing radiation exposure for patients. Iordache et al. [4] described the risks of radiation exposure associated with CT scans of the upper extremity, finding that the effective dose from a shoulder CT alone was 10.83 mSv, compared to 23.93 mSv when both the shoulder and elbow were scanned together. The lifetime attributable risk of cancer increased from 0.6 to 1.37 per 1,000 in males and from 0.73 to 1.69 per 1,000 in females.

Previous studies explored ultrasound-assisted techniques to measure the humeral torsion using the bicipital groove as a bony landmark [5-7]. Myers et al. [7] reported a strong correlation between humeral torsion measurements obtained via ultrasonography and humeral version measured by CT. However, past studies using ultrasonography evaluated the amount of torsion of the humerus by measuring the angle between the bicipital groove and the forearm, and their authors were unable to provide an exact humeral version angle measurement applicable in surgery.

We hypothesized that proximal humeral CT combined with ultrasonography could accurately predict humeral version without requiring additional imaging of the distal humerus. To validate this hypothesis, we applied a novel method to calculate humeral version using proximal shoulder CT, which is already included in routine preoperative planning, with the assistance of ultrasonography. We compared our novel humeral measurements with those obtained using the gold standard method.

METHODS

This study was approved by the Institutional Review Board of Veterans Health Service Medical Center (No. BOHUN 2021-07-021-001). Because of the low additional risk for patients and retrospective chart review study, there was no requirement for informed consent.

Humeral Version: CT Measurements

All CT scans were performed using the Siemens Somatom Definition Flash scanner (Siemens Medical Solutions). Conventional humeral version measurement was defined as the angle between the central axis of the humeral head and the transepicondylar axis of the elbow (Fig. 1) [8].

Fig. 1.

Conventional humeral version: angle between the central axis of the humeral head (solid line) and the transepicondylar axis of the elbow (dashed line).

Humeral Version: Ultrasound-Assisted Conventional Proximal Humerus CT

The angle between the central axis of the humeral head and the line bisecting the bicipital groove was measured on an axial slice of the CT scan of the humeral head. This was defined as the bicipital groove angle (Angle Bg) (Fig. 2A). For the ultrasonographic measurement of humeral torsion, two examiners, one fellowship-trained orthopedic surgeon and one orthopedic resident, performed sonographic measurements individually. To assess inter-observer and intra-observer reliabilities, ultrasonographic measurements were performed twice by each examiner. After the first examiner completed the measurements, the second examiner immediately repeated the procedure. The patient was placed in a supine position, with the shoulder abducted to 60° to 90° and the elbow flexed. The first examiner placed a linear ultrasound probe on the anterior shoulder (Fig. 2B). The probe was aligned perpendicular to the long axis of the humerus in the frontal plane, ensuring that the midpoint of the bicipital groove appeared in the center of the ultrasonogram (Fig. 2C). Next, the second examiner rotated the humerus until the line connecting the apexes of the greater and lesser tuberosities was parallel to the horizontal plane (Fig. 2D) [7]. The angle between the forearm and ultrasound probe, which was positioned perpendicular to the humeral shaft, was recorded. This was defined as the ultrasound probe angle (Angle Up) (Fig. 2E). Angle Bg and Angle Up were then summed, and humeral version was calculated by subtracting this sum from 90° (Fig. 3).

Fig. 2.

(A) Bicipital groove angle (Angle Bg): the angle between the central axis of the humeral head and the line bisecting the bicipital groove was measured on an axial slice of the computed tomography scan of the humeral head. (B) The patient is positioned supine with the shoulder abducted to 90° and the elbow flexed. The first tester places a linear ultrasound probe on the anterior shoulder. (C) The probe is aligned perpendicular to the long axis of the humerus in the frontal plane, ensuring that the bicipital groove appears in the center of the ultrasound image. (D) Then, the second tester rotates the patient's humerus until the line connecting the apexes of the greater and lesser tuberosities is parallel to the horizontal plane. (E) Ultrasound probe angle (Angle Up): the angle between the forearm and the ultrasound probe, which was positioned perpendicular to the humeral shaft.

Fig. 3.

(A) Humeral version measurement. (B) Illustration of bicipital groove angle (Angle Bg) measurement. (C) Illustration of ultrasound probe angle (Angle Up) measurement. Humeral version was calculated by subtracting the sum of Angle Bg and Angle Up from 90°.

RESULTS

The ICC values for ultrasound-assisted humeral version measurements demonstrated excellent intra-tester reliability (ICC=0.924; 95% CI, 0.857–0.960) and good inter-tester reliability (ICC=0.872; 95% CI, 0.727–0.942). The mean humeral version measured by CT was 30.4°±15.1°, whereas the ultrasound-assisted measurement was 32.8°±14.5°. Patient demographics, along with mean values and SDs for ultrasound-assisted humeral version measured using CT are presented in Table 1. There was a strong linear correlation between the two measurement methods (Fig. 4). The Pearson correlation coefficient indicated a very strong correlation (r=0.915, r²=0.838, P<0.001), and the concordance correlation coefficient was 0.903 (95% CI, 0.824–0.947). The derived regression equation was as follows:

Table 1.

Patient demographics and version measurements

Fig. 4.

Strong linear correlation between humeral version measured by computed tomography (CT) and ultrasound-assisted CT. Ultrasound measurement=−0.976+0.957×CT measurement.

Ultrasound measurement=−0.976+0.957×CT measurement.

The ICC values for humeral version measurements obtained via CT and ultrasound-assisted CT also showed excellent reliability (ICC=0.905; 95% CI, 0.813–0.951). The statistical correlations are presented in Table 2. A Bland-Altman plot was used to assess agreement between the two measurement methods. The mean difference between the two techniques was 2.38°, indicating that ultrasound-assisted measurement produced slightly higher values than CT measurement. The 95% limits of agreement ranged from −14.37° to 9.61° (Fig. 5). The mean difference between CT and ultrasound-assisted measurements was 2.38°±6.12°. The differences between CT and ultrasound-assisted measurements did not show significant variation according to sex, age, side (dominant vs. non-dominant), height, weight, or BMI. However, differences were observed according to the Hamada classification. The median difference for Hamada classifications 1 and 2 was 0.100 (range, −1.35° to 2.35°), whereas for Hamada classifications 3, 4, and 5, as well as osteoarthritis, the median difference was 6.50° (range, 1.47°–9.45°) (Table 3).

Table 2.

Statistical correlations between humeral version measurements obtained via CT and ultrasound-assisted CT

Fig. 5.

Bland-Altman plot showing agreement between the novel measurement method and the gold standard method. The mean difference between the two techniques is 2.38°, indicating that ultrasound-assisted measurement produced slightly higher values than computed tomography measurement. The 95% limits of agreement ranges from −14.37° to 9.61°.

Table 3.

Statistical differences between CT and ultrasound-assisted measurement

DISCUSSION

Here, we propose a novel method to calculate humeral version using conventional shoulder CT scans of the proximal humerus, which are commonly used for preoperative planning of RTSA, and simple ultrasound measurements. Previous studies explored the use of ultrasonography to measure humeral torsion [5-7,9-16]. However, these studies did not directly provide exact humeral version measurements but rather measurements that were correlated with CT-based gold-standard assessments. Our findings suggest that humeral version can be accurately measured using preoperative CT scans with ultrasound assistance, supporting our hypothesis.

Humeral version plays a crucial role in RTSA. Charles et al. [17] highlighted the importance of restoring native humeral retroversion and lateral humeral offset in RTSA. They demonstrated that postoperative humeral retroversion deviating minimally from preoperative values (within 10°) results in better external rotation outcomes. Although debate exists regarding the significance of humeral component version in RTSA, Wiater et al. [18] reported that humeral component version does not significantly affect outcomes following RTSA. However, they only compared fixed humeral component versions of 0° and 30°, without considering individualized humeral versions tailored to each patient. In contrast, Oh et al. [19] compared clinical and functional outcomes of individualized retroversion with fixed 20° retroversion and reported that individualized retroversion provided superior postoperative range of motion, pain relief, and functional scores. These findings underscore the importance of preoperative humeral version measurement.

When measuring humeral version, concerns exist regarding additional radiation exposure and increased costs associated with CT imaging of the distal humerus [4,20]. To address this, Jeon et al. [20] proposed a novel method for assessing postoperative individualized humeral component retroversion in RTSA without requiring CT scans of the distal humerus. In their study, they measured preoperatively the bicipital groove rotation angle using whole humerus CT scans, a measurement that is identical to the Angle Up measurement recorded in our study. Their method focused on minimizing radiation exposure, but to measure the postoperative humeral component version without CT scans of the distal humerus, preoperative exposure of the distal humerus is inevitable. Our combined findings indicate that it is much more practical to measure preoperative and postoperative humeral version values without exposing the distal humerus to additional radiation.

Our novel method is particularly accurate for measuring humeral version in proximal humeri with lower levels of bony degeneration. In our study, patients with glenohumeral osteoarthritis and advanced cuff tear arthropathy (Hamada grades 3, 4, and 5) showed a weaker correlation between ultrasound-assisted measurements and CT. Bony degeneration around the bicipital groove is commonly associated with glenohumeral osteoarthritis [21], whereas greater tuberosity rounding is a prominent bony change in advanced cuff tear arthropathy [22]. Our ultrasonographic measurement technique relies on identifying a prominent bicipital groove. In osteoarthritis and advanced cuff tear arthropathy, the higher likelihood of bony degeneration around the bicipital groove negatively affects measurement accuracy. However, we believe that despite a slight reduction in accuracy, our measurement technique is still valid in patients with severe bony destruction.

This study has several limitations. First, we relied heavily on the anatomical morphology of the bicipital groove. Our results indicate that in cases of severe osteoarthritis or advanced rotator cuff arthropathy, degeneration of the bicipital groove may lead to discrepancies in results between our method and the gold standard method. This limitation may be particularly relevant because these conditions are common in patients with RTSA. Therefore, our novel method is not applicable to patients with proximal humeral fractures with damage to the bicipital groove. Second, although our method demonstrated excellent intra-observer and inter-observer reliabilities, minor measurement errors of humeral torsion may have influenced the results. In this study, we placed the patient’s arm in a non-rigid fashion on a table with the ultrasound probe held perpendicular in the examiners hand. To enhance the accuracy of measurement, placing the patients in rigid frames with ultrasound holder fixed at 90° could be used. Third, this was a retrospective study with a limited number of patients. Thus, further studies with larger sample sizes are required to evaluate the effectiveness of our method, particularly in patients with severe osteoarthritis and advanced rotator cuff arthropathy. Despite these limitations, our novel ultrasound-assisted humeral version measurement method offers a promising approach for reducing radiation exposure during preoperative planning for RTSA.

CONCLUSIONS

Ultrasound-assisted measurement of humeral version in combination with conventional shoulder CT provides an accurate and reliable alternative to whole-humeral CT measurement. This method minimizes radiation exposure and cost while maintaining high correlations and reliability, and could be applied to patients without severe bony degeneration who need RTSA.

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