Download Variations in Measurements of Upper and Lower Ends of Humerus

Variations in Measurements of Upper and Lower Ends of Humerus
1
PRIYA RANGANATH†, 2BALASUBRAMANYAM V††
ANJALI T. OLLAPALLY*, ARUN ALEX* & BIBIN SEBASTIAN*
1
Bangalore Medical College & Research Institute, Bangalore 560002, Karnataka
2
St. John’s Medical College, Bangalore 560034, Karnataka
KEY WORDS: Measurements. Variation. Humerus. Upper and lower ends. Bangalore
sample.
ABSTRACT:
The present study was conducted on 40 humeri (18 left and 22 right). In
this study, at the upper end, the average of the circumference of anatomical neck was 12.98 cm,
surgical neck was 8.84 cm, width of bicipital groove was 0.76 cm, surface area of the head was
24.41 sq.cm. At the lower end, the circumference of medial part of trochlea was 5.23 cm,
middle part was 3.4 cm, lateral part was 4.3 cm, capitulum was 3.65 cm, length of medial
epicondyle was 1.85 cm and volume of olecranon fossa was 1.59 ml. Ten humeri (4 of left side
(10%) and 6 of right side (15%)) had supratrochlear foramen.
Associate Professor, Anatomy
Professor, Anatomy
*
Students, St. John’s Medical College
the acromion in the shoulder region and covered by
the deltoid. It produces the shoulder’s round contour.
The greater tubercle continues towards the shaft as
the lateral lip of the intertubercular sulcus. Between
the tubercles is the intertubercular sulcus or the
bicipital groove. The upper end of the humerus tapers
into the shaft as an ill-defined ‘surgical neck’.
The lower end of humerus is wider transversely
and has articular and non-articular parts. The articular
part joints with radius & ulna at the elbow and is
divided into a lateral, convex capitulum and a medial,
pulley-shaped trochlea. Non-articular condyle
includes medial and lateral epicondyles, olecranon,
coronoid and radial fossae. The capitulum is less than
half a sphere, it includes anterior and inferior surfaces
of condyle laterally, but not its posterior surface. It
articulates with discoid radial head, which abuts
inferior surface in full extension but slides on to the
anterior surface during flexion. The trochlea is like
part of a pulley, occupying anterior, inferior and
posterior surfaces of humeral condyle medially; it is
separated laterally form capitulum by a faint groove;
all aspects of its medial margin project. It articulates
with trochlear notch of ulna. In extension the
South Asian Anthropologist, 2011, 11(2): 181-183
New Series ©SERIALS
INTRODUCTION
The humerus is the longest and largest bone in the
upper limb. It has two expanded portions (the upper
and the lower ends) and a shaft. The upper end includes
a head, neck and greater and lesser tubercles. The head
forms about one-third of a sphere. The articular surface
is covered by hyaline cartilage. The humeral articular
surface is about four times the area of the glenoid cavity
of the scapula, only part of it being in the glenoid
contact in any position of the joint. The anatomical
neck is a slight constriction directly adjoining the
articular head’s margin. It indicates the line of capsular
attachment of the shoulder joint, except at the
intertubercular sulcus. The lesser tuberosity projects
prominently forward just beyond the anatomical neck
and continues downwards as the medial lip of the
intertubercular sulcus. It has a smooth muscular
impression palpable through the deltoid.
The greater tuberosity is the most lateral part of
the upper end of the humerus and it projects above
†
††
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Priya Ranganath, Balasubramanyam V., Anjali T. Ollapally, Arun Alex & Bibin Sebastian
inferoposterior trochlear circumference contacts the
ulna, but in flexion trochlear notch slides on to the
anterior aspect, the posterior being uncovered. The
projecting medial trochlear edge is a main determinant
of the angulation between long axes of humerus and
ulna when the forearm is extended and supinated. The
medial epicondyle is a blunt medial projection on the
medial condyle; it is subcutaneous and usually visible
in passive flexion. Its smooth posterior surface is
crossed by ulnar nerve in a shallow sulcus as it enters
the forearm, and here the nerve can be rolled against
the bone. If it is jarred against the epicondyle,
characteristic tingling sensations result. Distally
anterior epicondylar surface is marked by attachment
of superficial forearm flexors. Medial humeral border
ends at medial epicondyle and is distally the medial
supracondylar ridge.
A deep hollow, olecranon fossa, on the condyle’s
posterior surface, proximal to trochlea, contains apex
of olecranon in an extended elbow. Its floor is always
thin and may be deficient. It is occasionally perforated
to form a supratrochlear foramen or septal aperture
(Williams,’95).
Due to the variations in measurements of the
upper and lower ends of humerus and its involvement
in various types of fractures, the present study was
conducted.
MATERIALS AND METHODS
The present study was conducted on 40 humeri
(18 left and 22 right) of unknown sex and age available
at the Department of Anatomy, St. John’s Medical
College, Bangalore. The bones were studied for
variations in the upper and lower end. The parameters
observed were
1. circumference of anatomical neck
2. circumference of surgical neck
3. width of bicipital groove
4. surface area of head
5. circumference of medial part of trochlea
6. circumference of middle part of trochlea
7. circumference of lateral part of trochlea
8. circumference of capitulum
9. length of medial epicondyle
10. volume of olecranon fossa
The circumferences, width of bicipital groove at
the upper end of bicipital groove, and length of medial
epicondyle were measured by using a thread and a
ruler. The boundary of the head was traced on a tracing
paper and the resulting figure was placed on graph
sheet to calculate the surface area. The volume of the
fossa was measured by filling the fossa with water
and measuring the amount of water using measuring
jar.
RESULTS
In the present study, the following measurements
were observed:
1. circumference of anatomical neck: 13.05 cm
(left) and 12.92 cm (right)
2. circumference of surgical neck: 8.76 cm (left)
and 8.92 cm (right)
3. width of bicipital groove: 0.77 cm (left) and
0.75 cm (right)
4. surface area of head: 23.75 sq.cm (left) and
25.06 sq.cm (right)
5. Circumference of medial part of trochlea was
5.09 ± 0.64 cm (left) and 5.35 ± 0.59 cm
(right)
6. Circumference of middle part of trochlea was
3.41 ± 0.46 cm (left) and 3.39 ± 0.48 cm
(right)
7. Circumference of lateral part of trochlea was
4.17 ± 0.7 cm (left) and 4.4 ± 0.49 cm (right)
8. Circumference of capitulum was 3.57 ± 0.4
cm (left) and 3.74 ± 0.47 cm (right)
9. Length of medial epicondyle was 1.88 ± 0.39
cm (left) and 3.74 ± 0.47 cm (right)
10. Volume of olecranon fossa was 1.48 ± 0.25
ml (left) and 1.68 ± 0.42 ml (right)
Four humeri of left side (10%) and 6 of right side
(15%) had supratrochlear foramen.
DISCUSSION
In the present study of the upper end of humerus,
the average of the circumference of anatomical neck
was 12.98 cm, surgical neck was 8.84 cm, width of
bicipital groove was 0.76 cm, surface area of the head
was 24.41 sq.cm. These measurements could not be
compared with other authors because of lack of
published material.
Variations in Measurement of Upper and Lower Ends of Humerus
Regarding the lower end of humerus,
supratrochlear foramen or septal apertures may occur
in 4-13% of individuals, more frequently on the left
side and in females. Racial variations of 4.1-58% have
been reported (Bergman,’54). In an examination of
1744 arm bones, septal apertures were found in 4.2%
of whites and 12.8% of American Negroes
(Trotter,’43). In the present study, ten humeri (25%)
had supratrochlear foramen. The difference could be
due to ethnic variations in the population group
studied.
The average of the circumference of medial part
of trochlea was 5.23 cm, middle part was 3.4 cm,
lateral part was 4.3 cm, capitulum was 3.65 cm, length
of medial epicondyle was 1.85 cm, volume of
olecranon fossa was 1.59 ml. These measurements
could not be compared with the other authors, as there
was no published information available.
The axillary and the posterior circumflex humeral
vessels wind around the surgical neck. Dislocations
and fractures tend to occur here resulting in injury to
the nerve and vessels. Since the head of the humerus
does not fit exactly into the glenoid cavity of the
scapula, dislocations are very common in the shoulder
joint. Fractures are also common at this site, and with
the advent of prostheses for compound fractures, a
particular size is required for different individuals.
So there is a need for manufacturers of prostheses
and the orthopedician to know the variations in
measurements of the upper end of humerus while
using prostheses to suit different population groups.
The medial epicondyle can be avulsed by the
medial collateral ligaments of elbow joint if the
forearm is forcibly abducted. The ulnar nerve can be
injured at the time of the fracture, can become
involved later in the repair process of the fracture (in
the callus), or can undergo irritation on the irregular
bony surface after the bone fragments are reunited.
Due to fracture at this level, damage to or pressure on
the brachial artery can occur; the circulation of the
forearm may be interfered with (Snell, 2000).
Most adult distal humeral fractures involve the
articular surface. Lateral condylar fractures are much
commoner than medial fractures. Jupiter has classified
bicolumn fractures based on orientation of major
fracture lines. The AO/ASIS classification is being
used more frequently:
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Type A: Periarticular / extra-articular distal
humerus fractures: A1, avulsion fracture; A2,
metaphyseal: A3, metaphyseal with comminution.
Type B: Partial intra-articular fracture with or
without column involvement: B1, lateral condylar: B2,
medial condylar; B3, articular fracture without
column.
Type C: Entire articular fracture with both column
disruption; C1, no significant articular or metaphyseal
comminution; C2, no articular comminution but
significant metaphyseal comminution; C3, both
articular and metaphyseal comminution.
Classification of capitulum fractures:
Type I: Hahn-Steinthal: fracture in coronal plane
Type II: Kocher-Lorenz: sleeve fracture of
articular surface with little osseous bone.
Type III: comminuted.
Classification of olecranon fractures: common
with varied mechanisms of injury and fracture
patterns. Multiple classification patterns have been
developed; no single system is accepted widely
(Miller, 2000).
The knowledge of these variations is important
in orthopedics while operating on a fracture when they
use different types of nails and screws for a compound
fracture. Since there are ethnic variations in the size
and shape of the upper and lower end of humerus,
this study could be useful in manufacturing the
instruments which will be suitable for different
population groups.
REFERENCES CITED
Williams, P. L., L. H. Bannister, M. M. Berry, P. Collins, M.
Dyson, J.E. Dussek, and M. W. J. Ferguson 1995. In: Gray’s
Anatomy, 38th edition, p 623-625, Churchill Livingstone:
London.
Snell, R. S. 2000. In: Clinical Anatomy for Medical Students,
pp. 499, 6th edition. Lippincott, Williams and Wilkins :
Philadelphia.
Miller, M. D. 2000. In: Review of Orthopedics, pp. 500-502. 3rd
edition. W. B. Saunder’s Company: Philadelphia.
Bergman, R. A., A. K. Afifi and R. Miyauchi 1954. In: Illustrated
Encyclopedia of Human Anatomic Variation: opus V: Arm:
humerus. skeletal systems: upper limb.
Trotter, M. 1943. Septal apertures in the humerus of
American Whites and Negroes. Am. J. Phys. Anthropol.,
19: 213-227.