CT-based measurement and analysis of distal humerus morphology in healthy adults from Northern China

Abstract

Background

This study aims to investigate the morphological characteristics of the distal humerus in healthy adults from northern China using computed tomography and three-dimensional reconstruction techniques and compared whether there were diferences in morphology among populations from diferent geographical regions.

Methods

The CT data of 80 patients were imported into Mimics software for three-dimensional reconstruction and measurement. The differences in distal humeral morphological parameters between different genders and sides were compared, and the correlation between the parameters was explored. The distal humeral morphological parameters between Western and Chinese populations based on current and previous pooled results were compared.

Results

Thirty-one morphological parameters were measured and analyzed in this study. The average (and standard deviation) of capitellum depth, capitellum width, capitellum height, distal humerus width, epitrochlea width, and humeral metaphyseal width was 10.83 ± 1.18 mm, 17.60 ± 2.06 mm, 21.10 ± 2.03 mm, 44.38 ± 4.07 mm, 12.02 ± 1.90 mm and 58.95 ± 4.86 mm, these parameters were significantly higher (P < 0.001*) in males than females. The capitellum width (r = -0.300, P = 0.007*), anterior lateral trochlear depth (r =-0.227, P = 0.043*), medial crest coronal tangential angle (r = 0.307, P = 0.006*), olecranon fossa volume (r = -0.408, P < 0.001*), olecranon fossa surface area (r = -0.345, P = 0.002*) and coronoid fossa surface area (r = -0.279, P = 0.012*) were significantly correlated with the age of the subjects. In the comparison of people from different regions, the capitellum height, lateral trochlear high, trochlear groove high, trochlear depth and medial trochlear high of the Western population were 23.25 ± 2.56 m, 21.6 ± 2.20 mm, 17.8 ± 2.00 mm, 17.80 ± 2.00 mm, 29.9 ± 4.10 mm, are significantly higher than those in the Chinese population. while capitellum width (15.55 ± 2.68 mm) and capitellum depth (9.00 ± 1.00 mm) were slightly lower.

Conclusion

The findings provide a basis for the design of distal humeral orthopaedic implants, ensuring greater alignment with the anatomical structure of the distal humerus and improved surgical outcomes. Furthermore, the study provides a reference point for the diagnosis and classification of distal humeral diseases, as well as guidance for patient rehabilitation.

Introduction

The distal humerus, a crucial component of the elbow joint, significantly contributes to its normal physiological function and activity. Distal humerus fractures, comprising roughly 2% of adult fractures and account for 33% of humeral fractures, have gradually increased incidence due to age increased and the escalating occurrence of high-energy accidental injuries in contemporary society [1, 2]. The complex interactions between the bone structure, articular surface, and soft tissue attachments of the distal humerus significantly affect its overall function and contribute to the overall stability and mobility of the elbow joint. The morphological study of the distal humerus plays a vital role in clinical research, for instance, in the design process of the distal humeral prosthesis, it is essential to create a prosthesis that conforms to the anatomical morphology of the elbow joint can maximize the contact area with the proximal articular surface of the ulna and radius, thereby reducing contact stress, which is beneficial to avoid wear of the articular surface, and improve surgical quality and prosthesis life [3]. It is worth noting that the majority of current distal humeral prostheses and plates have been designed with the Caucasian race as the reference point. A Chinese study reported the mismatch issue of the AO-designed extra-articular distal humerus locking plates in the posterolateral column and shaft of the distal humerus, as well as the mismatch problem of the Coonrad-Morrey prosthesis with the Chinese population [4, 5]. Therefore, it is necessary to accurately understand the morphological characteristics of the distal humerus and to compare the morphological characteristics of the distal humerus between people in different regions by combining the current and previous research results provides an essential theoretical basis for improving the quality of clinical diagnosis and treatment of distal humerus-related disorders [6].

Some researchers employ vernier calipers to directly measure the distal humerus of cadaver specimens without establishing a standardized coordinate system which may result in significant errors [7]. An alternative approach is to directly measure the morphological parameters of the distal humerus on X-ray images [8]. However, X-ray images are two-dimensional planar images that exhibit overlapping anatomical structures and poor consistency in shooting positions, these measurement methods are more suitable for angle than size measurement [9]. In recent years, advances in CT and 3D reconstruction techniques have provided researchers and clinicians with unprecedented opportunities to explore the three-dimensional complexity of the skeletal structure of the distal humerus, allowing accurate measurement and detailed analysis of the morphology of the distal humerus. In this study, the CT data were imported into the Mimics software, where a standardized coordinate system and standardized cross-sections were established. This approach was taken in order to eliminate the problem of poor consistency in the subject’s shooting position.

In this research, CT and 3D reconstruction methods were employed to accurately gauge the configuration of the lower end of the humerus in the northern Chinese population. The aim was to explore the gender and side differences in the morphology of the distal humerus and analysis the correlation between age, gender and other variables. This study presents a synthesis of research data from both domestic and international sources, with the objective of elucidating the morphological variations in the distal humerus between Chinese and Western populations. The goal of this effort is to enhance the understanding of the distal humerus and elbow joint, optimize the distal humeral morphology database, and provide reference data for the design of distal humeral orthopedic implants and the diagnosis and treatment of diseases.

Methods and materials

The study was approved by the Ethics Committee of our hospital (2020-083-1) and conducted by the Declaration of Helsinki. The data source for this study was CT images of the humerus from the Hebei Medical University Third Hospital from 2019 to 2021. Image data were acquired in the Digital Medical Imaging and Communication (DICOM) standard format. All CT images were scanned by experts on a 64-slice spiral CT machine (Somatom Sensatim 64, Siemens Healthcare, Germany), with the following parameters: 120 kV tube voltage; auto-mA tube current; 512*512 pixels; 25 cm slice field and the thickness of the scanning and reconstruction slices was 0.625 mm. Exclusion criteria included: (1) incomplete baseline data: lack of scanning layers, unable to perform 3D reconstruction (2) sub-optimal image quality: the quality of 3D reconstruction is poor and cannot accurately reflect the actual condition of the distal humerus of the subject, (3) middle and lower humerus fractures, bone defects, bone diseases, bone tumors, or severe osteoporosis or autoimmune diseases: trauma and disease lead to changes in the anatomical structure of the distal humerus, which can increase research errors.

Some researchers imported CT data into Mimics software to evaluate and analyze the shape and relationship between the scapula and the glenoid, and achieved good results [10]. A study employed the method to assess the accuracy of three-dimensional virtual surgery for free fibula mandibular reconstruction. The results demonstrated no significant discrepancy in angle and shape when compared to postoperative imaging outcomes [11]. Referring to our previous research methods on the shoulder joint and proximal humerus, CT image processing and 3D modelling were performed using Mimics software (Materialise, Leuven, Belgium) in this study [12]. The influence of the patient’s position on the CT image was eliminated by realigning the examination plane. The 3D humerus model was reconstructed from the CT thresholds and measured using the 2D images and the 3D model. As shown in Fig. 1, the 3D reconstruction of the distal humerus is adjusted to the standard anatomical position, and a sphere is drawn at the humeral head and the humeral trochlear groove using the sphere drawing tool. Its position is adjusted in the horizontal and sagittal planes so that the cross-section of the sphere essentially coincides with the humeral head section and the humeral trochlear groove section, respectively. So that the multiple sagittal sections of the humeral head and the humeral trochlear groove roughly match the corresponding areas of the ball, ensuring that the ball is the best fit for the humeral head and trochlear groove. The centers of the two balls were then calibrated in the horizontal and coronal planes as the center of the humeral head ball and the center of the humeral trochlear groove, respectively. The humeral flexion axis was defined as the straight line passing through the center of the humeral head and the center of the humeral trochlear groove. The plane passing through the elbow flexion axis and parallel to the humeral shaft axis was defined as the coronal plane. Then, with the elbow flexion axis as the axis of rotation, adjust the horizontal plane to a position perpendicular to the coronal plane and determine the direction of the sagittal plane to establish the final coordinate system [13, 14]. The parameters to be measured include: (1) morphological parameters of the distal humerus: capitellum depth (CD), capitellum width (CW), capitellum height (CH), distal humerus width (W), epitrochlear width (EW) and humeral metaphyseal width (HMW), (2) The trochlear shape parameters: offset distance of trochlear (ODT), anterior medial trochlear depth (AMTD), posterior medial trochlear depth (PMTD), trochlear depth (TD), anterior lateral trochlear depth (ALTD), posterior lateral trochlear depth (PLTD), anterior medial trochlear width (AMTW), posterior medial trochlear width (PMTW), anterior lateral trochlear width (ALTW), posterior lateral trochlear width (PLTW), lateral trochlear height (LTH), trochlear groove high (TH), medial trochlear high (MTH), trochlear width (TW), (3) Angle parameters: Humeral axial angle (HAA), medial crest coronal tangential angle (MCCTA), lateral crest coronal tangential angle (LCCTA), medial crest sagittal tangential angle (MCSTA) (positive posterior), lateral crest sagittal tangential angle (LCSTA) (positive anterior), (4) Three-dimensional (3D) morphological parameters of the distal humerus: medial epicondyle volume (MEV), olecranon fossa volume (OFV), coronoid fossa volume (CFV), olecranon fossa surface area (OFSA), coronoid fossa surface area (CFSA), medial epicondyle surface area (MESA). The measurement method and parameters are shown in Fig. 2.

Fig. 1

Diagram of the measuring axis. Create a small simulated sphere at the humeral head and trochlear groove, respectively, to adhere to anatomical structures as closely as possible. Position the straight-line OX, which connects the center of the humeral head sphere and the center of the humeral trochlear groove, to the humeral flexion axis. The OXZ plane corresponds to the coronal plane. This plane is parallel to the humeral axis. The horizontal plane is the OXY, perpendicular to the coronal plane. Eventually, the sagittal plane is determined to be the OZY plane

Fig. 2

Measurement parameters and methods. (a) W is the width of the distal humeral articulation from the most medial circle on the trochlea to the most lateral circle on the capitellum. CW is the length between the two endpoints of the humeral head in the cross-section.TW is the distance between the projection of the most anterior point of the medial trochlear margin on the bending axis and the projection of the junction groove between the humeral head and the lateral trochlear margin on the bending axis. EW is the vertical distance between the medial epicondyle’s apex and the humerus’s medial epicondyle base. AMTW/PMTW is the vertical distance between the trochlea’s medial leading and trailing edges and the trochlear groove. ALTW/PLTW refers to the vertical distance between the leading and trailing edges inside the trochlea and groove. HMW is the linear measurement between the furthest lateral point of the humerus’s lateral epicondyle and the medial epicondyle’s furthest medial point.CD is from the most anterior point on the capitellum to the axis. ALTD/PLTD is the vertical distance from the trochlea’s outer leading edge and trailing edge to the shaft is the trochlea’s axial depth. AMTD/PMTD is the vertical distance from the trochlea’s inner leading edge and trailing edge to the axis.TD is measured from the most anterior point of the trochlear groove to the most posterior point. ODT is the vertical distance between the trochlear groove’s center and the humerus’s axis. MTH/LTH is the diameter of the largest fitting circle of the medial trochlear rim and lateral trochlear margin by translating the sagittal plane. TH/CH is the diameter of the fitted circle obtained by translating the sagittal plane through the trochlear groove and capitellum. (b) MCCTA/MCSTA is the tangent angle formed by the curve’s endpoints projected from the contour of the distal humerus’s medial cortical crest to the coronal and sagittal planes. LCCTA/LCSTA is the angle of the tangent chord formed by the curved ends projected from the contour of the lateral cortical crest of the lower part of the upper arm bone to the coronal and sagittal planes. HAA is the angle formed by the humeral shaft axis and the flexion axis of the distal humerus on the radial side in the coronal plane. MEV/MESA divides the medial epicondyle of the humerus by translating the coronal plane to its base. Then, measure the surface area and partial volume from the humerus’s base to the medial epicondyle’s apex. CFV/CFSA is the humerus surface that accommodates the volume of depression in the ulnar styloid process and the cortical surface area. OFV/OFSA is the depression in the ulnar styloid process, and the humerus’ surface accommodates the cortical bone’s surface area

Statistical analysis was performed using SPSS 26 (SPSS Inc, Almond, NY). Individual parameters are described by mean and standard deviation. The K-S test was used to test the normality of all parameters. The independent samples t-test was used to compare gender and side differences for continuous variables with normal distribution, and the Kruskal-Walli’s test was used for continuous variables with non-normal distribution. Pearson correlation analysis was used for continuous variables with normal distribution to explore possible correlations between parameters, and Spearman correlation analysis was used for continuous variables with non-normal distribution. P < 0.05 was considered statistically significant.

To compare whether there are differences in the morphological measurement data of the distal humerus between the Chinese population and the Western population, we use the formula shown in Fig. 3 to summaries the mean and standard deviation of previous studies. The pooled data of the Western and Chinese people were subjected to the pooled data T-test, and P < 0.05 was considered statistically significant [15,16,17,18,19,20].

Fig. 3

Methods for pooling statistical parameters across multiple studies. (a) The formula pooled the average of multiple studies into one; (b) pooled the standard deviation of multiple studies into one

Results

A total of 80 subjects were included in this study, including 45 males and 35 females, the distribution of age group 20–29 years (26, 32.5% cases), followed by 30–39 years (20, 25% cases), 40-49years (18, 22.5% cases), 50-59years (12, 15% cases), 60-69years (3, 3.75% cases), and 70–79 years (1, 1.25% cases), mean age was 38.02 ± 12.28 years, a total of 44 cases of left humerus and 36 cases of right humerus were identified. The data characteristics of the subjects’ test parameters are shown in Table 1.

Table 1 Morphological parameters

Morphological parameters of distal humerus

The mean and standard deviation of CD, CW and CH measured at the flexion axis cross-section were 10.83 ± 1.18 mm, 17.60 ± 2.06 mm and 21.10 ± 2.03 mm, respectively. The W, EW and HMW were 44.38 ± 4.07 mm, 12.02 ± 1.90 mm and 58.95 ± 4.86 mm, respectively.

Humeral trochlea shape parameters

The humeral trochlea is an important anatomical structure for maintaining the normal motion of the elbow joint. It is the anatomical basis of the functional range of motion of the elbow joint. The mean TH, LTH and MTH were 16.63 ± 1.96 mm, 18.79 ± 2.07 mm and 23.87 ± 2.40 mm, respectively. The AMTD, PMTD, ALTD and PLTD were 12.01 ± 1.40 mm, 12.03 ± 1.79 mm, 9.97 ± 1.19 mm and 14.94 ± 1.57 mm, respectively. The TW, AMTW, PMTW, ALTW and PLTW were 26.78 ± 2.96 mm, 11.94 ± 1.60 mm, 8.98 ± 1.35 mm, 7.81 ± 1.81 mm and 11.92 ± 1.92 mm, respectively. The ODT and TD were 5.98 ± 1.66 mm and 16.28 ± 1.95 mm, respectively.

Angle parameters

The means of the HAA in 80 subjects was 86.22 ± 3.27°. The MCCTA and LCCTA were 43.05 ± 7.53° and 16.03 ± 7.32° respectively. The MCSTA and LCSTA were 7.52 ± 11.00° and 37.31 ± 9.10°, respectively.

3D shape parameters

The MEV were 2334.49 ± 591.95mm³. The OFV and CFV were 1613.52 ± 401.63mm³ and 388.42 ± 165.57mm³, respectively. The OFSA, CFSA and MESA were 481.84 ± 91.13 mm²,134.59 ± 36.85 mm² and 751.61 ± 134.77 mm², respectively.

Gender differences and left- right side differences

As shown in Table 2, CD (P < 0.001*), CW (P < 0.001*), CH (P < 0.001*), W (P < 0.001*), EW (P < 0.001*), and HMW (P < 0.001*) were significantly higher in males than in females. There was no significant difference between the sexes in the shape parameters of the humeral trochlea except for OTD (P = 0.098), AMTD (P < 0.001*), PMTD (P < 0. 001*), TD (P < 0.001*), ALTD (P < 0.001*), PLTD (P < 0.001*), AMTW (P < 0.001*), PMTW (P = 0.01*), ALTW (P < 0.001*), PLTW (P < 0.001*), LTH (P < 0. 001*), TH (P < 0.001*), MTH (P < 0.001*), TW (P < 0.001*) of males were significantly higher than those of females, and MEV (P < 0.001*), OFV (P < 0.001*), CFV (P = 0.003*), OFSA (P = 0.001*), CFSA (P = 0.007*), MESA (P < 0.001*) were also significantly higher in men than in women. However, the gender differences in the angle parameters included in this study were insignificant. There was no significant difference in the distal humerus parameters between the left and right sides, except for the HAA (Right: 85.41 ± 3.07°, Left: 86.88 ± 3.31°, P = 0.045*) and PLTW (Right: 12.47 ± 1.72 mm, Left: 11.47 ± 1.98 mm, P = 0.02*).

Table 2 Gender differences and left-right side differences

Correlation analysis of parameters of distal humerus

The results of the correlation analysis are shown in Tables 3, 4, 5 and 6. Among them, CW (r = -0.300, P = 0.007*), ALTD (r = -0.227, P = 0.043*), MCCTA (r = 0.307, P = 0.006*), OFV (r = -0.408, P < 0.001*), OFSA (r = -0.345, P = 0.002*) and CFSA (r = -0.279, P = 0.012*) were significantly correlated with the age of the subjects. There was no correlation between the angle parameters of the distal humerus. However, the correlation analysis results between the distal humerus morphological parameters were positively correlated. In summary, there is a broad and complex correlation between the measured parameters.

Table 3 Shape parameters of the humerus schematic diagram of the correlation between morphological parameters of the distal humerus

Table 4 Correlation analysis between humeral trochlea shape parameters

Table 5 Correlation analysis of angle parameters

Table 6 Correlation analysis of 3D morphological parameters

Comparative analysis with other populations

As shown in Table 7, the mean values of CD (P < 0.001*), LTH (P < 0.001*), TH (P < 0.001*) and TD (P < 0.001*) were smaller in the Chinese population compared with the Western people, while CW (P < 0.001*) and CD (P < 0.001*) were more prominent. There was no significant difference in W (P = 0.263), TW (P = 0.08) and HMW (P = 0.087) between the two groups.

Table 7 Comparison of morphological parameters of some distal humerus between Eastern and Western populations

Discussion

In this study, the distal humerus of the northern Chinese population was scanned and reconstructed using CT and 3D reconstruction techniques, and the geometric parameters of multiple samples were measured to describe the morphology of the distal humerus. These measurement data provide the morphological parameters of the distal humerus in the northern Chinese population and add to the anatomical data of the distal humerus. This research helps to improve the surgeon’s understanding of the morphology of the distal humerus. At the same time, it also helps to improve the design and clinical application of orthopedic implants, including elbow prosthesis and internal fixation plate of distal humerus fractures. It provides valuable guidance on treatment strategies for distal humerus trauma and other conditions.

Most previous studies on measuring the distal humerus have been based on direct measurement of bone specimens using callipers or 2D measurements based on radiographs. It should be noted that these measurement methods do not establish a coordinate system to standardize the measurement process. There is overlap in the radiographs and inconsistencies in taking positions, which can lead to significant errors. In this study, we use CT data and the Mimics software to reconstruct a 3D model of the distal humerus and obtain standardised cross-sections. This approach effectively circumvents measurement errors that may arise from image overlap and inconsistent subject postures, thereby enhancing the accuracy and reliability of the measurement data.

The morphometric parameters of the anatomical structures of the distal humerus were measured in detail. The whole distal humerus’s shape, the humerus’s medial condyle, and the humeral capitulum are described in detail using CD, CW, CH, W, EW, and HMW. In this study, the CH (21.10 ± 2.03 mm) was not equal to the CW (17.60 ± 2.06 mm). Similarly, Sabo et al. used CT data to measure the elbow joints of 50 cadavers [15]. Their results showed that the average height of the CH was 23.2 ± 2.8 mm and the CW was 13.9 ± 2.3 mm. Wevers et al. used the circular fitting method to measure the sagittal slices of 6 humeral capitesllums [21]. They found that the CW ranged from 14.5 to 21.5 mm and the CH ranged from 19.2 to 23.7 mm. This indicates that the shape of the humeral capitellum is closer to an ellipsoid than a sphere, but it is worth noting that there are certain differences in the definition and measurement methods of width and height in various studies, so the appearance of the humeral capitellum needs further discussion. The humeral trochlea is a crucial anatomical structure in the elbow joint’s motion. Fourteen parameters have been chosen to describe its anatomical morphology for enhanced understanding of its morphology. The results of this study showed that the AMTW (11.94 ± 1.60 mm) was larger than the PMTW (8.98 ± 1.35 mm), and the PLTW (11.92 ± 1.92 mm) was larger than the ALTW (7.81 ± 1.81 mm), which indicated that both the internal and external trochlear margins ran posterior to lateral and anterior to medial. The PLTD (14.94 ± 1.57 mm) was larger than the ALTD (9.97 ± 1.19 mm), while the difference between the AMTD (12.01 ± 1.40 mm) and PMTD (12.03 ± 1.79 mm) was not obvious, which indicated that the external trochlear margin protruded more posteriorly. The MTH (23.87 ± 2.40 mm) was greater than LTH (18.79 ± 2.07 mm). This is similar to the results of Yang et al. [18]. When restoring complex distal humeral fractures or considering implant design for total elbow arthroplasty, surgeons should pay more attention to the geometry of the medial and lateral trochleae, which may help restore normal elbow motion. The position of the distal humerus fracture plate is usually placed on the medial or lateral aspect of the distal humerus adjacent to the medial and lateral humeral cristae. To optimize the design of the steel plate and enhance its fit while reducing complications such as nonunion, pain, limited mobility, screw loosening, and even plate fracture caused by improper plate sizing, we have not only employed the commonly used HAA but also introduced innovative methods such as MCCTA, LCCTA, MCSTA, and LCSTA. These date enable us to accurately evaluate the angles of the distal humerus, thus improving the parameter related to the distal humerus fracture internal fixation plate. The precise analysis of MEV, OFV, CFV, OFSA, CFSA and MESA by computer 3D reconstruction technology helps improve the surgeon’s spatial perception and understanding of the distal humerus structure. By measuring the shape, angles, and three-dimensional design of the distal humerus, healthcare professionals and researchers can utilize these parameters to grasp the morphological characteristics of the distal humerus.

Regarding gender differences, 21 parameters were significantly more prominent in males than females (P < 0.05*). The distal humerus of males was broader and thicker than that of females, and there were noticeable structural differences, however, there was no gender difference in the angular parameters. This conclusion is similar to the findings of Desai et al. which suggests that the male distal humerus is larger in size than the female distal humerus, yet there is no discernible difference in morphology [16]. When designing bone implants in the distal humerus, gender differences should be considered to design implants that better match the anatomical structure and biomechanics of the humerus, thereby improving the clinical treatment effect and achieving differentiated and precise treatment of orthopedic conditions. The difference between the left and right sides was only found in the HAA (p = 0.045*) and the PLTW (p = 0.02*). The reason for the difference in our analysis may be that different dominant hands may lead to differences in bilateral muscle strength, and the difference in muscle traction and mobility may lead to changes in bone structure [22, 23]. On the other hand, although our previous research found no left-right difference in the proximal humerus [24]. But among the 31 parameters in this study, only 2 parameters (0.065%) were different in the left-right comparison. This result may be caused by statistical bias due to insufficient sample size. Therefore, the number of subjects needs to be expanded in further research to avoid possible errors.

OFV (r = -0.408, P < 0.001*), OFSA (r = -0.345, P = 0.002*), CFSA (r = -0.279, P = 0.012*), CW (r = -0.300, P = 0.007*) and ALTD (r = -0.227, P = 0.043*) were negatively correlated with age, whereas MCCTA (r = 0.307, P < 0.006*) was positively correlated with age. With increasing age, the human bone structure undergoes mechanical adaptive and degenerative changes [25, 26]. The changes in trabecular bone and bone surface curvature may be the reasons for the differences in these parameters with age. Similar to the proximal humerus, there is a complex relationship between the dimensions of the distal humerus, suggesting that the morphology of the distal humerus has a synergistic developmental mechanism [24].

To investigate whether there is a difference between the Chinese population and the Western population in the morphology of the distal humerus, it is found that the CH in the Chinese population is significantly lower than that of the Western population, but the CW and TD are considerably higher than those of the Western population. The different changes of the humeral capitulum in diverse populations place higher demands on the design of internal fixation devices such as bone plates and screws in this part, and according to their specific morphological characteristics, the creation of internal fixation devices is optimized to improve the clinical diagnosis and treatment of diseases such as elbow fracture. The LTH, TH, MTH and TD in the Chinese population were significantly smaller than in the Western population. The SD of all differential parameters was more significant in the Western population, indicating that the dispersion of humeral parameters was more critical in the Western population. This suggests that the Chinese population may need a more diminutive size and a smaller range of internal plants. It is imperative that further research be conducted to collect additional morphological parameters of the distal humerus in individuals from disparate geographical regions. Furthermore, the measurement process must be optimised and the accuracy of the measurement data must be enhanced. Once a sufficient database has been obtained, it will be possible to combine artificial intelligence, surgical robot systems and 5G communication systems to establish an intelligent orthopaedic implant design system. This will enable the automatic design of steel plates, highly integrated surgical robots and remote robotic surgery. The utilisation of a comprehensive database facilitates the generation of orthopaedic implants that are more congruent with the human anatomical structure, thereby markedly enhancing the safety of robotic surgery.

Limitations

First of all, the sample size of the population was insufficient, resulting in potential biases. In addition, this study did not consider the effect of BMI on the morphology of the distal humerus, which may reduce the reliability of the results. CT scans cannot include the thickness of articular cartilage in the measurement, which will have a certain systematic impact on the construction and measurement process, resulting in possible errors in the measured values [27].

Conclusions

This study provisionally established a morphological dataset of the distal humerus in the northern Chinese population. Increasing the measurement of the medial and lateral crests of the distal humerus can better explore the curvature of the distal humerus. The results of the study showed that the distal humerus size of men is larger than that of women, and the distal humerus size of the Chinese population is smaller than that of the Western population. Therefore, in the surgical treatment of distal humeral fractures and the design of orthopedic implants, factors such as angles and sizes should be considered as much as possible, and the anatomical differences between different regions and genders should be fully considered. In future studies, subjects from multiple regions should be collected to increase the sample size to ensure the accuracy of statistical differences. X-ray results can be combined to increase the authenticity of angle measurement, and MRI examinations can be used to exclude the influence of cartilage tissue on experimental research to further enhance the accuracy of research results.