Supratrochlear foramen : an incidental finding in the foothills of Himalayas

A ll au th or s ab id e by th e A ss oc ia tio n fo r M ed ic al E th ic s (A M E) e th ic al ru le s of d is cl os ur e. Abstract Introduction The lower end of the humerus has two large fossae, the olecrenon fossa and the coronoid fossa, separated by a thin bony plate that rarely bears an opening known as supratrochlear foramen. Supratrochlear fracture of humerus is very common in the paediatric age group, and it can alter the line of fracture as well as management. Due to its clinical relevance, its presence cannot be ignored. This report discusses a case of a supratrochlear foramen. Case report During routine osteology demonstration, we encountered the humerus with supratrochlear foramen. Morphometric analysis was done and compared with the previous literatures. Conclusion This foramen can alter the radiological findings during examination and may get misdiagnosed as osteolytic lesion or cystic lesion. Supratrochlear foramen can alter the line of fracture as it is linked with a small medullary canal, which can modify our decision of point of entry of the nail in the medullary nailing procedure. Therefore, its clinical importance cannot be ignored. Supratrochlear foramen: an incidental finding in the foothills of Himalayas


Introduction
A thin plate of bone usually separates olecranon fossa and coronoid fossa of the humerus.At times, this bony plate remains perforated known as supratrochlear foramen (STF), septal aperture or intercondylar foramen of the humerus.The thin plate of bone is always present in between olecranon and coronoid fossae till the age of 7, later it may persist or get absorbed 1 .Initial reporting of STF was done by Meckel in 1825.STF may cause hyperextension at the elbow joint 2 .Occurrence of STF is well documented in other animals 3,4 .STF is of great importance to anthropologists claiming it as one of the points in a satisfying relationship between humans and lower animals 2 .
Seventy-five percent of all injuries of the paediatric age group are fractures of the supracondylar region of the humerus 5 .Intramedullary nailing of the humerus is sometimes required in the treatment of supracondylar fracture, and it is relatively more difficult in the presence of STF 2 .This foramen is always associated with the narrow medullary canal and hence route of pin entry in intramedullary nailing is still a point of debate.Therefore, it is important to have knowledge of STF in the pre-operative planning, treatment of supracondylar fractures and to decide route of pin entry in medullary nailing 6 .This report discusses a case of a STF.

Case report
During regular osteology demonstration for undergraduate medical students, we encountered a right-side humerus with oval-shaped STF (Figures 1 2).Morphometric analysis revealed its horizontal diameter as 6.22 mm and vertical diameter as 4.64 mm.Edges of STF were 24 mm distal to the medial epicondyle, 29 mm to the lateral epicondyle and 16 mm to the lower border of the humerus.Careful examination of the bone was done, and no other abnormality was noticed.Photographic record of anatomical landmarks was made.

Discussion
STF may produce stress and alter fracture of line patterns associated with supracondylar fracture.It may also increase tendency of supracondylar fracture even in case of relatively low-energy trauma 7 .The mean transverse and vertical diameters of STF reported in the present case are in concordance with the findings of Krishnamurthy et al. 2 and Nayak et al. 8 .Our results were not consistent with the findings of Veerappan et al. 9 (Table 1).Shapes of STF were classified as round, oval and triangular and with sieve-like aperture according to Veerappan et al. 9 , with the oval shape being most common.It shows that the shape of the foramen in the present case is in accordance with the results of Veerappan et al. 9 and Nayak et al. 8 .Distance of STF from medial epicondyle in the present study is 24 mm and from lateral epicondyle is 29 mm.The mean distance from medial epicondyle was calculated as 26.1 and 28 mm on left-and right-side humerus, respectively, while it was reported as 23.84 mm by Veerappan et al. 9 This is almost similar to our case, but the distance from lateral epicondyle is 5 mm more than the case reported by Veerapan et al. as 24.06 mm.

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Corresponding author Email: alok.sxna@gmail.com 1 Department of Anatomy, Veer Chandra Singh Garhwali Government Medical Science and Research Institute, Srinagar, Uttarakhand, India 2 Department of Anatomy, Government Medical College, Kota, Rajasthan, India

Figure 1 :
Figure 1: Anterior view showing the oval-shaped STF at the lower end of humerus.

Figure 2 :
Figure 2: Posterior view showing the oval-shaped STF at the lower end of the humerus.