Morpho-metrical analysis of upper humerus- A study from Central Maharashtra

Introduction

In upper body largest bone is humerus. The upper end of humerus comprises of rounded head with proximal and medial part of upper end of the bone. It forms articulation with glenoid cavity of scapula.1 The head is joined to shaft by constricted neck and two eminences, with both tubercles.2 The head of the humerus forms less than half a spheroid. Its smooth articular surface which is thicker centrally is covered with hyaline cartilages. When arm is at rest by the side it is directed upwards, medially and backwards to articulate with glenoid cavity of scapula. Proximal fractures of humerus are common injuries. They occur along with epiphyseal lines of proximal humerus and within humeral segments.3

The shoulder joint is ball and socket type of joint formed by articulation of humerus (hemispherical head) and shallow glenoid cavity of scapula. The sizes of Humeri & Glenoid cavity can impact decision-making during surgery for shoulder replacement and also shoulder instability. The authors have emphasized importance of Glenoid sizes in Asian population and its impact on decision of Bankart Vs Latarjet procedure. Though shoulder joint is highly movable but few disease conditions like rheumatoid arthritis avascular necrosis of humeral head and rotator cuff tear hampers its movements and requires arthroplasty for better movements.

There is limited literature on the shoulder bony morphological parameters in the Indian population, also the surgical correction of humerus requires measurements of humeral upper end which differ with reference to race and geographical area. Reconstruction of proximal humeral defect with custom made acrylic prosthesis is less expensive and effective, which can be used in developing countries.4

Most of the prosthesis designs are based on western measurements. Shoulder prosthesis should accurately mimic proximal shoulder with glenoid anatomy to recreate the shoulder biomechanics. The bony morphology of Indians may be different from that of the western countries. Also, dimensions of proximal end of humerus vary.5 Usually length of Indian population is smaller as compared to western population.6

Estimating the stature of the individual from bones and as well as reconstructions of life from the human skeletal still remains a challenge for many anthropologists, researchers and forensic experts. Statures estimated from the human skeletal remains overall is an important step in assessing health as well as general body size trends among the given populations.

Morphometrical analysis of bone is very important not only for the reconstruction surgery but also for determining the gender of dead bodies. The examination of the upper and lower limb asymmetries can be useful to medical anthropologists, archeologists, forensic experts and for medico legal studies. The humerus confers important advantages over other long bones of human body in that its entire outline can readily be traced on total body X-ray absorptiometry images, and its shape can be modelled as a cylinder with excellent accuracy.7 This study was done to determine-

This is done mainly to compare the variations in size of humerus in Indian population.

Materials and Methods

Our study was a retrospective study conducted for 20months from 20-5-21 to 5-1-23 in the dept. of anatomy MGM medical college,Aurangabad .The study was approved by the ethical committee of MGM medical college on 21-5-21. The sample size taken was 61because only that much bones are available in our departmental bone bank. All the intact/non damaged humeri were included in the study whereas damaged and Pathological humeri were excluded.

The Materials required for study included Sliding Vernier caliper, Scale, Non elastic thread and Osteometer.

Statistical analysis was done with the help of SPSS 25. Descriptive and analytical statistical analysis was done. Analysis was done by Pearsons correlation. Linear multivariant regression equation was calculated.

Procedure

The present study was performed on 61 cadaveric humeri(31 left sided and 30 right sided). All were of unknown age and gender. Length of humerus, Head of Humerus, AP diameter and Medio-Lateral diameter of humerus head was calculated as follows-

Total length (L)

Functional length of humerus which is distance between upper and lower end in anatomical position is recorded in mms with the help of osteometer.1

Figure 1

Total length

Antero posterior dimeter of head(AP)

Distance between middle point of anatomical neck anteriorly to middle point of neck posteriorly.1

Figure 2

Antero posterior diameter of head (AP)

Medio lateral dimeter of head (MLD)

Distance between middle point of upper margin of greater tubercle till middle point of medial margin of surgical neck.4

Figure 3

Medio lateral diameter of head(MLD)

Head height (H)

Distance between highest point of anterior margin of anatomical neck to lowest point of posterior margin of anatomical neck.4

Figure 4

Head height(H)

Results

Out of 61 cadaveric humeri that were collected, 31 were left sided and 30 were right sided. The result of length of humerus, Head of humerus, AP diameter of humerus and MLD of humerus is as follows-

The length of humerus of right side is more as compare to left side. AP diameter of head is almost equal of both side. Mediolateral diameter of head is more of left side whereas head height is more of left humerus.

Discussion

One of the longest bone in the human body is humerus. In forensic study and anthropological practice it plays an important role helps to identify the length from the segmental measurements. This method is an essential step in assessing health, sexual dimorphism and the general body size that trends among the past populations.2 For morphometric analyses use of well-preserved bones of the human body is of utmost importance. Besides the bone structure of the pelvis and cranium, other bones like humerus, tibia, femur, sternum, ulna, talus, calcaneus, radius bones are also used in anthropological studies. Because of the bone deformities formed due to chemical factors and mechanical factors, humerus is the common bone used for the sex determination. Therefore, humerus has been frequently used by researchers in forensic and anthropological studies.3

This study was conducted on 61 human cadaveric humeri. Of these, based on side we found that 31 were left sided and 30 were right sided. We have measured length, head size, AP and MLD of these humeri. Mean and standard deviation was calculated using vernier caliper, osteometer, scale and thread.

According to our study, the mean±SD for length of humerus was 308.42±17.85mm for left sided and 311.30±18.15mm for right sided humerus. The total mean±SD was 309.84±17.91mm.

In the study conducted by S. Desai et al which was conducted in Bijapur, Karnataka, maximum length of humerus was 292.3±22.9mm on right and left was 289.45±21.8mm. Their values were quite lower as compared to our study.8 The other comparable studies are mentioned in Table 4.

The combined total length of humeri in our study was, 309.84 ±2.53mm. In the study conducted by Akman et al, the combined length was 305.95mm ± 1.6mm.12 This was a Turkish study. In the study conducted by Papaloucas et al, which is Athenian study, the combined length was 330.67mm ± 3.5mm.13 In one study conducted in Istanbul, the combined length was 324.16mm ± 32.21mm.14 So, our combined length of humerus was much smaller as compared to Athenian and Istanbul study. .

The next parameter taken by us was AP diameter of head. In present study it was 39.106±2.791 mm on left side and 39.54±2.544 mm on right side. The combined AP diameter was 39.32 ±2.61 mm. In the study conducted by Moumita Chatterjee et al it was 39.06± 3.26 mm on right side and 38.82±2.71 mm on left side respectively. This is quite comparable to our study.15 In the study conducted by Sinchal Dutta et al, it was 38.946+ 3.383 on right side and 38.208+ 3.684mm and left side respectively.16 While in study conducted by Ayadin et al, the transverse diameter on right and left side was 38.29±3.04mm and 38.66±3.92mm respectively.17 In the study conducted by Azari Ashutsh et al, the transverse combined diameter was 39.65±2.97mm respectively which is relatable to our study.18 Quite higher AP diameter of head was found in the study of Dipti Sahu et al and it was 40.1 ± 2.8mm.19

In present study, the medio-lateral diameter of Humerus head was 42.73±3.743mm on left side while 43.196± 2.727mm on right-hand side. The total MLD was 42.959±3.264mm. In the study conducted by Moumita Chatterjee et al, the maximum vertical diameter of head was 35.56±3.26 on right side and 35.19±3.38 on left side.15 This is quite higher as compared to our study. In the study conducted by Lokanadham et al the vertical diameter of head was 32.66± .31 in males and 29.6± .41 in females.20 The difference in values in both the above studies could be due to, our study was conducted on cadaveric humeri while their study was conducted on human beings. In the study conducted by Aydin et Al, the vertical diameter was 42.41±3.25mm and 42.94±4.01mm respectively for right and left side.17

In our study, the head height with respect to mean±SD was 31.019±2.739mm on left side and 30.82±2.35mm on right side. The combined head height was 30.92±2.53mm.The head height was calculated from distance between highest points of anterior margin of anatomical neck to lowest point of posterior margin of anatomical neck. We could not find many studies mentioning the head height. The head is important part of humerus as it helps in formation of ball and socket joint and it serves as the insertion point for muscles which make up the shoulder girdle.

Anthropometry measurements are extremely useful to estimate stature and bone length from the skeletal remains of body. It’s a very important step in assessing health as well as general body size trends away the given populations is stature estimated from the human skeletal remains. It also has an unmeasurable role in the identification of persons that are missing into medical legal investigations, finding the mean values of different humerus segment which helps in forensic and anthropometric practice. For the assessment of the living stature of the individual, assessment of long bones of the individual is very important in anthropological practice for morphometric analysis in case of pelvis, cranium and long bones such as tibia and femur of the lower limb collectively remains the best. In case of absence of lower limb bones the estimation of living stature can be done by the help of remains of upper limb bones like humerus, radius and ulna.

There is limited literature on the shoulder bony morphological parameters in the Indian population, also the surgical correction of humerus requires measurements of humeral upper end which differ with reference to race and geographical area. Reconstruction of proximal humeral defect with custom made acrylic prosthesis is less expensive and effective, which can be used in developing countries.4

Conclusion

The morpho-metric dimensions of right side of humerus was more than that of left side. There was variability in dimensions which was found in different studies. The length of humerus is shorter as compared to Athenian and Istanbul study. Proper measurements are required when surgical procedures are to be done. More studies should be conducted measuring head heights.

Source of Funding

None.

Conflict of Interest

None.