Radiological study of carrying angle among male and female and its clinical importance

Introduction

The elbow joint is in a fully extended and supinated position, forearm diverges laterally forming an angle with the upper arm. This is referred to as ‘CARRYING ANGLE’ or ‘CUBITAL ANGLE’. Angle is neutralized when the forearm is flexed and pronated from an extended and supinated position.1 The carrying angle of the elbow is generally regarded as being greater in females than in males and is considered to be a secondary sex characteristic.2 The carrying angle permits the forearms to clear the hips in swinging movements during walking and is important when carrying objects.3 This angle is 155–180° or, if one uses the supplementary angle, usually 0–25°. The supplementary angle is the smaller angle of deflection.4 Supplementary angle = 180° – carrying angle. Various authors have used the term carrying angle for both the angles.5

Carrying angle is partly due to more distal position of the tip of the medial lip of the trochlea. A curved ridge joins the prominences of coronoid process and olecranon, the obliquity of the shaft of the ulna to this ridge accounts for most of the carrying angle at the elbow.6 Knowledge of the carrying angle is important anthropologically for differentiation of sex. It is also useful for the reduction of common complications of supracondylar fractures. Loss or increase in carrying angle results in cosmetic deformities and also for designing total elbow prosthesis.7

Materials and Methods

Elbow X-rays were collected in various clinical laboratories and Amaltas Hospital in and around Dewas, Madhya Pradesh. The study was conducted at Amaltas Institute of Medical Science, Dewas. Totally 70 elbow radiographs of adults were collected which included 35 males and 35 females. The age ranged from 18 to 76 years, and the mean age was 35 years. The carrying angle was measured by drawing a line passing through the mid-axis of the lower third of the humerus and another line along the mid-axis of the upper third of the forearm passing in between the radius and ulna through a superior radioulnar joint. Both the lines were extended to meet at the midpoint of transepicondylar line where the angle was measured.1

Figure 1

1: Anteroposterior radiographic view of the right elbow of an adult female. It shows the carrying angle (*). The supplementary angle between the mid-axis of the humerus (AH) and the mid-axis of forearm (FA). The two lines (AH and AF) meet at the mid-point of Trans-Epicondylar Distance (TECD)

The bones show physiological growth between 1 to 16 years. So, we have selected x-rays between 16 to 40 years. Normal anteroposterior radiographic views with an extended elbow and fully supinated forearm were examined. Exclusion criteria: Age: below 15 years. I. Obliquity or rotation of view was excluded. ii. No rotation was censured by appreciating the two humeral epicondyle and slight superimposition of the radial head, neck and tuberosity over the proximal ulna excluded. iii. Subjects with cubitus valgus and varus deformities. iv. Subjects undergone supracondylar fracture and total elbow arthroplasty are excluded.

Result

Statistical analysis is in which Mean, Standard Deviation (SD) and t-test were included to assess any Gender differences. The level of significance was defined as a p-value of less than 0.0001.

The angle is significantly greater in females than in males. In males, it ranges from 8.80° to 18.50° with a Mean and SD of 14.3±2.74°, while in females it ranges from 17.60° to 29.80° with a Mean and SD of 21.92±3. 17°. P value is <0.0001`.

Discussion

Knowledge of the measurement of the carrying angle of the elbow and its variations is important to evaluate traumatic elbow injuries in elbow disorders. Punia et al. did not find any significant difference between males and females. We found a greater difference between males and females. Purkait R. and Chandra et al. studied the carrying angle by measuring the trochlear angle and the olecranon-coronoid angle. According to them, the olecranon-coronoid angle showed a statistically significant difference between males and females.2, 8 In our study, the angle was measured between the longitudinal axis of the arm and the forearm, which showed a greater gender difference. Yilmaz et al.9 confirmed a greater difference between males and females, which supports the present study. Park S., Kim E., et al.10 used three-dimensional radiographs to measure the carrying angle, but we used image ‘J’ software to measure the carrying angle. Both the studies showed a greater gender difference.

Greater carrying angle in females can be considered their secondary sexual characteristic because there is no difference in carrying angle between males and females until puberty, after which it increases in females.5 It might also be due to their increased joint laxity, allowing a greater degree of elbow extension and hence a greater carrying angle.11, 12 Steel FLD et al.6 (1958) studied the carrying angle in the left upper limb of 100 adults (50 males and 50 females) in London using radiographs.

The measurement of carrying angle was done using a goniometer by Paraskevas G et al.,5 showing 12.230 ± 0.30 in males and 15.77 0 ±0.41 0 in females. When these angles were compared with our study, they showed a greater angle difference. Khane GN et al. found that carrying angle is inversely related to the height of the person. But we consider only the gender difference.13

Papadopoulos and Paraskevas G. et al.5 found an increased carrying angle in the dominant upper limb compared to the opposite upper limb. Our study is invariable on the sides of the upper limb. Bernardo Barellos and Terra et al.14 stated that the carrying angle physiologically increases as age progresses. The angle gradually increases from childhood to sixteen years of age. We have selected X-rays from 16–40 years to exclude physiological variation. Potter, Afkison, and Elftman considered the carrying angle a secondary sex characteristic, which is much more significant in our study with an increased carrying angle in females than males.12, 15

Considering our studies and comparing the values, it is clear that a greater angle in females than males was observed, showing a great gender difference. The mean and standard deviation in males is 14.3±2.74° and 21.92±3.17° in females.

Conclusion

The present study was conducted to compare the carrying angle values of males with those of females. The study was conducted in the Dewas region of Madhya Pradesh, and it included 70 radiographs (35 males and 35 females) from the age group of 16–40 years. We conclude the present study, which confirms a significant gender difference in the carrying angle between females and males. By considering the above fact, the gender of an individual can be identified in the radiographs. Values may assist the orthopaedics in correcting the elbow deformities.

Source of Funding

None.

Conflict of Interest

None.