STUDY OF INCIDENCE AND OSSIFICATION OF SESAMOID BONES IN HANDS OF SOUTH INDIAN POPULATION

Address for Correspondence: Dr. Archana. A, Assistant Professor, Department of Anatomy, Medciti Institute of Medical Sciences, Hyderabad, Telangana, India. E-Mail: archu.konduri@gmail.com Introduction: The word Sesamoid bone is attributed to “Galen” who described small bones of hands and feet which resembled the seed of the “Sesamum Indicum “an ancient East Indian plant used for purging by the Greeks. The mechanical role of sesamoid bones is to protect the tendon from damage and in some cases increase the efficiency or mechanical advantage of associated muscle. They begin as cartilaginous nodules that undergo endochondral ossification during early to late childhood. There is a rather extensive variability in the reported incidence of sesamoid bones in the hand within different ethnic groups and populations. Materials and Methods: The present study was a retrospective review of 99 plain AP and Lateral view radiographs of 82 adults (54males and 28 females >17years of age)and 17 children (males and females<17 years)attending the Radiology department of Gandhi Hospital/Gandhi Medical College during 2011-2012 to assess the location, incidence and ossification of sesamoid bones in the hands of South Indian population. Results: The most common incidence of sesamoid bones was found at the MCP and IP joints of thumb (97.4% and 41.5%) respectively, followed by 5th digit (16.25%)and least incidence was found at the 4th digit(0%).Ossification commenced first in the thumb at 12 years in females and 14 years in males and ended at the age of 16 years in both sexes. Conclusion: This anatomical data can help the physicians and surgeons in the diagnosis and management of disorders of sesamoid bones.


INTRODUCTION
nodules that are embedded within certain tendons, where they pass over a joint of hand, Sesamoid bones are small round or oval shaped The present study was a retrospective review of hand radiographs to assess location, incidence and ossification of sesamoid bones.A total of 99 plain Anteroposterior and Lateral view hand radiographs of 82 adults(54 males and 28 females of age group >17 years) and 17 children (<17 years)were studied during 2011-12 in patients referred to Radiology department of Gandhi Medical College/Gandhi Hospital, Secunderabad.On the basis of hospital data only South Indian population was included.The radiographs were studied for the location and number of sesamoid bones on the palmar aspects of MCP&IP joints of all the digits of hands .The commencement and completion of ossification of sesamoid bones was studied in the radiographs of 4-17 years age group.The results were analysed for side and sexual variations in the incidence.wrist, knee and foot [1,2].They protect the tendon from damage and in some cases increase the efficiency or mechanical advantage of their associated muscle [1].Most sesamoids begin as cartilaginous nodules that undergo endochondral ossification during early to late childhood [1].Ossification commences first at the age of 10 years in females and 11 years in males and is completed by the age of 13 years and 14 years respectively [3].Sesamoid bones are usually asymptomatic, but may be associated with fracture dislocation, infection, inflammation, necrosis and tenosynovitis.Sometimes sesamoid bones can be misdiagnosed as fractures [4].
There is a rather extensive variability in the reported incidence of sesamoid bones in the hand within different ethnic groups and different populations [3].The present study has been taken up to assess the incidence ,ossification and location of sesamoid bones in the hands of South Indian population with the help of plain Anteroposterior and Lateral radiographs of hand to investigate the ages at which these bones will begin and complete ossification and also the sexual variation.

MATERIALS AND METHODS
in right and left hands of males and females.
Table I shows the distribution and percentage of incidence of sesamoid bones on the palmar aspect of MCP joints and IP joints in the right hands of adult males (also depicted in Bar Diagram 1).In thumb, MCP joints show an incidence of 96.9%[32 radiographs, of them 30.3%( 10 radiographs) were showing 2 sesamiod bones and the remaining 66.3% were single]and IP joints show single bone incidence of 39.4%(13 radiographs).In the MCP joints of index, middle and little fingers the single sesamiod bone incidence was 18.2%(6 radiographs),12.1%(4radiographs) and 21.2%(7 radiographs) respectively.NO sesamiod bones were found at MCP joints of ring finger and PIP&DIP joints of II-IV digits.
The incidence of sesamoid bones at each joint of the digits of hand were calculated separately  Table 2 shows the distribution and percentage of incidence of sesamoid bones on the palmar aspect of MCP joints and IP joints in the left hands of adult males (also depicted in Bar Diagram 2).In thumb MCP joints show an incidence of 95.2%[20 radiographs,of them 14.3%(3 radiographs)were found to have 2 sesamiod bones and the remaining 80.9% were single]and IP joints show single bone incidence in 23.8%(5 radiographs).In the MCP joints of index,middle and little fingers the incidence of single bone was 9.5%(2 radiographs),4.8%(1radiograph) and 9.5%(2 radiographs)respectively.NO sesamiod bones were found at MCP joints of ring finger and PIP&DIP joints of II-IV digits.The distribution of sesamoid bones in different locations between male and female subjects were statistically similar in hands(P=0.08;>0.05).The occurance of sesamoid bones in MCP joints of thumb(P=0.05)was statistically similar in males and females on both sides.Ossification Of Sesamoid Bones: The sesamiod bones in the thumb MCP joint were the first to be ossified.Table 7 shows the ossification of sesamoid bones in the MCP joints of thumb in 17 radiographs of hands in boys and girls of age 4-17 years.Ossification commenced in them at 12 years in females and 14 years in males and was completed by the age of 16 years in both the sexes.

DISCUSSION
Although sesamoid bones are generally asymptomatic there are several exceptions described in the literature,that they may cause painful syndromes and degenerative changes in response to overuse and trauma.They may be involved in fractures, periostitis as in Reiter's syndrome or may increase in size in conditions like Acromegaly.
In the present study,the sesamoid bones were found palmar to the MCP joint of thumb in 79 hand radiographs(97.5%) of which 24(30% had 2 sesamoid bones and the remaining were single.Only single sesamoid bone was found at the IP joint of 32(41.5 %) radiographs.Table 8 shows the comparative values of incidence of sesamoid bones at MCP&IP joints of thumb between various authors.

Fig. 1 :
Fig. 1: Plain AP Radiograph of the hand showing two sesamoid bones at MCP joint one at IP joint of thumb in right hand of male aged 30 years.
the distribution and percentage of incidence of sesamoid bones on the palmar aspect of MCP joints and IP joints of in the right hands of adult females (also depicted in Bar Diagram 3).In thumb MCP joints show an incidence of 100%[18 radiographs,of them 33.35(6 radiographs) were found to have 2 sesamoid bones and the remaining 66.7% were single]and IP joints show single bone incidence in 44.4%(8 radiographs).In the MCP joints of index,middle and little fingers the incidence of single seasamoid bone was 5.5%(1 radiograph), 5.5%(1 radiograph) and 16.7% (3 radiographs) respectively.NO sesamiod bones were found at MCP joints of ring finger and PIP&DIP joints of II-IV digits.

Fig. 2 :
Fig. 2: Plain radiograph of Right hand showing sesamoid bone at MCP joint of index finger in 20 years old female.

Table & Bar Diagram 4 :Fig. 3 :
Fig. 3: Plain radiograph of left hand showing two sesamoid bones at MCP joint of thumb and one at IPjoint of index finger in 40 years old female.

Fig. 4 :
Fig. 4: Plain radiograph of right hand of 4 years old male child with no sesamoid bones.

Fig. 5 :
Fig. 5: Plain AP Radiograph of hand showing commencement of ossification at MCP joint of thumb in 14 years old male child.
Archana.A et al.STUDY OF INCIDENCE AND OSSIFICATION OF SESAMOID BONES IN HANDS OF SOUTH INDIAN POPULATION.

Table & Bar diagram 1:
Distribution and percentage of incidence of sesamoid bones on palmar aspect of MCP&IP Joints in the digits of right hand in adult males.

Table & Bar
Diagram 2: Distribution and percentage of incidence of sesamoid bones on palmar aspect of MCP&IP Joints in the digits of left hand in adult males.

Table & Bar Diagram 3:
Distribution and percentage of incidence of sesamoid bones on palmar aspect of MCP&IP Joints in the digits of right hand in adult females.

Table 5 :
Comparing the incidence between right and left hands of males and females.

Table 6 :
Comparing the incidence between right and left MCP joint of thumb of males and females.

Table 7 :
Showing ossification of sesamoid bones in MCP Joints of the thumb in radiographs of hands of boys and girls between ages 4-17(n=17).

Table 8 :
Showing comparative values of incidence of sesamoid bones at MCP and IP joints of thumb between various authors.