Elbow Joint Anthropometry in Central Indian Population: A Cross-Sectional Study

ABSTRACT

Background:

The carrying angle of the elbow is a critical aspect of upper limb biomechanics, influencing arm movement, and hand precision. This study aims to assess elbow joint parameters, including the carrying angle, articular surface angle, and anatomical alignment to understand normal elbow morphometry and its variations based on age, sex, and side dominance.

Materials and Methods:

The study included 300 right-hand dominant, healthy volunteers aged 18–50 years. Elbow joint measurements were taken using anteroposterior (AP) and lateral radiographs. The carrying angle, articular surface angle, and other anatomical parameters such as the anterior humeral line (AHL) and radiocapitellar line (RCL) were measured.

Results:

The mean carrying angle on the dominant side was 10.19 ± 1.175° for males and 13.44 ± 0.610° for females, (P < 0.001). On the non-dominant side, males had a mean carrying angle of 9.72 ± 1.063°, and females had 13.38 ± 0.634°, also showing significant differences (P < 0.001). The articular surface angle was 82.8° ± 4.501°. The AHL intersected the capitellum in the middle third in 55.3% of dominant sides and 55% of non-dominant sides. The mean trans-epicondylar distance was 6.19 cm on the dominant side and 6.21 cm on the non-dominant side.

Conclusion:

This study provides valuable data on elbow joint anthropometry in the Central Indian population, revealing significant sex-based differences in carrying angle and alignment.

INTRODUCTION

The carrying angle of the elbow, formed between the humerus and forearm during full extension, is essential for upper limb biomechanics, enabling forearm clearance and precision in movement. This angle is influenced by factors such as age, sex, BMI, arm length, forearm length, and inter-epicondylar distance (IED) and is crucial in pediatric orthopedics for identifying abnormal elbow alignment affecting growth or injury prognosis.[1]

Racial and regional variations exist, with studies from Malaysia, Jordan, and India consistently showing females have larger carrying angles.[2] In cases of cubitus varus, Baumann’s angle difference of 0 or higher between affected and normal sides indicates an 80% likelihood of development.[3] Recent research highlights modified Baumann’s angle differences between dominant and non-dominant sides, negatively correlated with arm and forearm length and secondary sexual characteristics, with predictive equations developed for estimating the angle.[4] Despite the significance of elbow biomechanics and trauma, detailed anthropometric studies remain limited, prompting this investigation to ascertain elbow parameters in the central Indian population.

MATERIAL AND METHODS

This prospective cross-sectional study was conducted in the Department of Orthopaedics at NSCB Medical College and Hospital, Jabalpur (MP). A total of 300 right-hand dominant volunteers who met the inclusion criteria were enrolled.

Inclusion criteria

Participants aged 18 to 50 years provided written informed consent after detailed explanations of the study objectives. Ethical clearance was obtained from the institutional ethics committee.

Exclusion criteria

Exclusion criteria included age below 18 or above 50 years, upper limb trauma, restricted shoulder/elbow movement, growth or congenital abnormalities, and those unwilling to provide consent.

Carrying angle

The angle between the humeral shaft’s longitudinal axis and the ulna’s longitudinal shaft line [Figures 1 and 2].

Figure 1.

Carrying angle

Figure 2.

Articular surface angle

Articular surface angle

The angle between the humeral shaft and a transverse line across the distal trochlea and capitellum.

Anterior humeral capitellar line

A line was drawn along the anterior surface of the distal humerus and continued distally to record its relationship with the capitellum as anterior one-third, central one-third, or posterior one-third [Figures 3 and 4].

Figure 3.

Anterior humeral capitellar line

Figure 4.

Anterior humeral line and radiocapitellar line

Radiocapitellar alignment

To assess the alignment on the lateral radiograph between the radial head/neck and the capitellum, a line was drawn longitudinally along the central radial neck to assess its intersection point with the capitellum.

Statistical analysis

Data were analyzed using paired and unpaired t-tests for mean comparisons and Pearson’s correlation for continuous variables. Statistical significance was set at P < 0.05.

RESULTS

The carrying Angle was increases with the age and significantly larger among females then males in dominant and non dominant side [Table 1].

Table 1.

Carrying angle (in degrees) by age and gender in dominant and non-dominant side

Age Group		Male (Mean±SD)	Female (Mean±SD)	P
Dominant side	<20	9.55±0.51	–	<0.001
	20-29	9.63±0.58	13.32±0.47
	30-39	10.04±0.73	13.38±0.49
	40-49	10.75±0.44	13.72±0.84
	≥50	14.20±0.79	–
Non-dominant side	<20	9.00±0.00	–	<0.001
	20-29	9.20±0.40	13.02±0.52
	30-39	9.69±0.58	13.59±0.50
	40-49	10.03±0.38	13.68±0.69
	≥50	13.60±0.84	–

Articular surface angle, Trans epicondylar distance and anterior angulation in dominant and non dominant side [Table 2].

Table 2.

Articular surface angle and trans-epicondylar distance by dominance

Measurement	Dominant (Mean±SD)	Non-dominant (Mean±SD)
Articular surface angle (degrees)	82.8±4.501	81.9±4.432
Trans-epicondylar distance (cm)	6.19 (5.2 – 7.3)	6.21 (5.1 – 6.9)
Anterior angulation (degrees)	46.14±5.69	46.05±5.61

Anterior Humeral line in anterior one third and Radiocapitellar Line in anterior and middle one third was greater in non dominant side [Table 3].

Table 3.

Anterior humeral and radiocapitellar line analysis by dominance

Intersection Location	Dominant (%)	Non-dominant (%)
AHL - Anterior One-Third	16.7	17.3
AHL - Middle One-Third	55.3	55.0
AHL - Posterior One-Third	28.0	27.7
Radiocapitellar Line - Anterior One-Third	3.3	4.7
Radiocapitellar Line - Middle One-Third	89.0	89.7

DISCUSSION

The anthropometric study of elbow angles in Tibetan children reveals significant variations across ethnic groups. The carrying angle, essential for forearm clearance during movement, varies with sex (larger in females), limb dominance (larger in non-dominant arms), and height, though inconsistently. Understanding these variations is crucial for assessing upper limb deformities, particularly in pediatric and adolescent populations. The Baumann angle and lateral capitello-humeral angle are highlighted as key parameters for diagnosing and treating elbow deformities, such as cubitus varus and valgus, reinforcing the need for population-specific reference values.[5]

Iwamoto et al.[6] demonstrated that 3D planning reduces the margin of error for both humeral and ulnar components, resulting in better alignment and stability postoperatively. Prkić et al.[7] found that while 2D preoperative digital templating for TEA provides reliable measurements, it lacks predictive accuracy in certain cases, especially for implant sizing.

The clinical implications of these advancements extend beyond surgical precision to the overall function and quality of life. Conditions such as bursitis, dislocation, and epicondylitis can severely impair elbow function and often result from repetitive strain or trauma.[8]

CONCLUSION

Accurate diagnosis and treatment are essential to restoring functionality and minimizing morbidity. The integration of advanced imaging and tailored treatment protocols holds the potential to improve the management of these significant conditions.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.