The carrying angle: racial differences and relevance to inter-epicondylar distance of the humerus

The human carrying angle (CA) is a measure of the lateral deflection of the forearm from the arm. The importance of this angle emerges from its functional and clinical relevance. Previous studies have correlated this angle with different parameters including age, gender, and handedness. However, no reports have focused on race-dependent variations in CA or its relation to various components of the elbow joint. This study aimed to investigate the variations in CA with respect to race and inter-epicondylar distance (IED) of the humerus. The study included 457 Jordanian and 345 Malaysian volunteers with an age range of 18-21 years. All participants were right-hand dominant with no previous medical history in their upper limbs. Both CA and IED were measured by well-trained medical practitioners according to a well-established protocol. Regardless of race, CA was greater on the dominant side and in females. Furthermore, CA was significantly greater in Malaysian males compared to Jordanian males, and significantly smaller in Malaysian females compared to their Jordanian counterparts. Finally, CA significantly decreased with increasing IED in both races. This study supports effects of gender and handedness on the CA independent of race. However, CA also varies with race, and this variation is independent of age, gender, and handedness. The evaluation also revealed an inverse relationship between CA and IED. These findings indicate that multiple factors including race and IED should be considered during the examination and management of elbow fractures and epicondylar diseases.