Nutrient foramen of clavicle an anatomical and a topographic study:

Introduction

Nutrient foramen is an opening into the bone shaft for passage of blood vessels into the bone for its nourishment and growth, which is very vital for its development in the embryonic and fetal life.1 The clavicle it develops intramembranous and is the last bone to complete ossification and first to begin the process.2 It is the only long bone to lie horizontally displaying a double curvature. As known all bones have nutrient foramen, classically literatures describes that the clavicle has a small foramen present at the superior border at the middle one third of the bone transmitting nutrient artery and occasionally supraclavicular nerve.2 Various authors observed that Clavicle is supplied by periosteal artery3 and suprascapular artery.4,5 Supraclavicular nerve can get entrapped and cause Supraclavicular nerve entrapment syndrome, hence the through knowledge of the Foramina is very essential.

Aim

The aim of this study is to understand the detailed topographic anatomy of the neurovascular foramen in human adult clavicle to enlighten the operating surgeons the variations that could be encountered and prevent further complications.

Materials and Methods

The present study was conducted on 104 (54 right sides and 50 left) adult clavicle of unknown age and sex without an external damage from the department of Anatomy. All the bones were observed for the number of foramina, position location and direction. The data were collected on a standardized sheet and morphologically analyzed.

Results

From 104 clavicle various parameters were observed and noted as below mentioned.

Discussion

Long bones get their arterial supply from the nutrient artery, the supply from these arteries is vital and essential during active growth period and in yearly ears of ossification.6 The direction and position of the nutrient foramina is towards the growing end of the long bone in mammalian bone which can be variable at times and may alter during growth.7 Since clavicle lacks medullary cavity, absence of nutrient foramina can be justified8 and therefore does not depend on nutrient artery for its nutrition.3

In this study the neurovascular foramina were present in 97.11% of clavicle and majority of the foramina (93.2%) was directed towards the lateral end, indicating the medial end of the bone as the growing end supporting similar study by Havet et al.,5 Fischer and Carret,4 Kumar et al.2 Multiple foramina’s was observed in majority along with topographic location of the foramina’s being situated in the middle 1/3 of the clavicle in most of the cases.

Standard textbooks of anatomy state that the foramina were present at the inferior surface. But in the present study, we observed that in 44.2 % of the cases the foramina were present at the posterior surface (Figure 1) and were present at the inferior surface in 52.8% of the clavicles (Figure 2) and 2.8% of the clavicle had foramen at its superior surface (Figure 3).

5- 10% of clavicular fracture occur in middle 1/3 due to the natural double curvature of the bone.5 They reported that periosteal artery was always present on the superior surface and anterior border of the clavicle, but never on the inferior surface or posterior border. Their results showed that the periosteal arteries located between the muscular insertions could be compromised in case of displacements or fracture. They concluded that, if the clavicular fractures or non-unions cannot preserve the periosteal blood supply, bone grafting should be done.1

Nutrient foramina contain fascicle of the supraclavicular nerve along with nutrient artery as reported by Kumar et al.2 Gelberman et al.9 defined the supraclavicular nerve entrapment syndrome, the nerve injury has been attributed to the location of the branch of the supraclavicular nerve in the narrow canal of the clavicle.8 Shohei et al.10 reported that they have treated two patients who had entrapment neuropathy of the supraclavicular nerve attributable to an osseous tunnel of the clavicle and decompression of the entrapped nerve relieved symptoms in both patients. Fibrous and muscular structures in addition to nutrient canal contents could also be an Anatomical basis for the supraclavicular nerve entrapment syndrome as suggested by Jelev and Surchev.8

Figure 1

Clavicles showing the nutrient foramen at the inferior surface

Figure 2

Clavicles showing the nutrient foramen at the inferior surface

Figure 3

Clavicles showing the nutrient foramen at the superior surface

Conclusion

The present study shows that the nutrient foramina in the clavicle was present not only in the inferior surface but also present on the posterior surface in great numbers and majority of Clavicle had multiple foramens that outnumbered the clavicle with single foramen in contrary to described in classically Anatomy text books. The study on foramina of collar bone are limited, hence this study provides additional information about the morphology of the foramina in this atypical long bone. Knowledge of localization of nutrient foramina can be useful in wile operating through the bone in tissue salvaging procedures. We believe that a convention for the accurate anatomical description of these foramina is important.

Source of funding

None.

Conflict of interest

None.