AN ANATOMICAL STUDY OF MORPHOLOGY AND MORPHOMETRIC ANALYSIS OF CALCANEUM AND ITS TALAR ARTICULAR SURFACES

Address for Correspondence: Prof. Dr. Anbumani T L, Professor & H.O.D of Anatomy, Karpaga Vinayaga Institute of Medical Sciences, Maduranthagam, Tamil Nadu, India. E-Mail: anbumanitl@gmail.com Background and Aims: Calcaneum, also called as the “Heel Bone” is the largest and strongest tarsal bone in humans. It acts as the posterior pillar of the longitudinal arches of foot for the transmission of body weight. The Calcaneum articulates with the Talus bone superiorly by three articular facets, forming a Subtalar joint. In the present study, the variations of the Talar articular facets on the Calcaneum, presence of Calcaneal spur are observed along with morphometric analysis of Calcaneum. Materials and Methods: 110 dry Calcaneal specimens from the Department of Anatomy of our institution are used for this study. Digital vernier caliper is used for morphometric analysis. Observations: The Calcaneum is classified into different types based on the Talar articular facets. The presence of dorsal and plantar or inferior Calcaneal spur is observed and it is correlated with the different types of Calcaneum. Other morphometric parameters are also observed. The gender of the bone is not considered in the present study. Conclusion: Subtalar joint stability is influenced by the morphology of Talar articular facets on the Calcaneum. Facet morphology can be determined by the gait pattern or other environmental and genetic factors. A proper knowledge of the anatomy of Calcaneum and their variations in different parameters is necessary for a good clinical understanding and treatment outcome.

Table 1 shows the percentage incidence of types of Calcaneum.Type B4: Middle and posterior facets are fused with each other.Anterior facet is separate.
(Figure 6) Type B1 and B2 Calcaneii, in which the anterior and middle Talar facet are fused, is found in 76 bones which correspond to 69.1% of the bones.The Interfacet distance between anterior and middle facets are measured in Type A and Type B4 Calcaneum.Table 3 shows the percentage incidence of Calcaneum as per interfacet distance between anterior and middle Talar facets.The Interfacet distance between the anterior and posterior facets are measured in 106 bones out of 110 Calcaneum, as the anterior facet is absent in four bones.The interfacet distance ranged between 7mm to 20mm with a mean of 15mm.
The horizontal length of the Calcaneum was measured between the Cuboid articular facet anteriorly and the attachment for tendocalcaneus posteriorly.The length ranged between 5.5cm to 8.5cm, with a mean of 7.5cm.Table 4 shows the length of the right and left side Calcaneii.respectively.12% of Calcaneum had both dorsal and inferior spurs (Figure 7).Table 5 and Table 6 shows the correlation of Calcaneal spurs to the type of Calcaneum and their percentage incidence respectively.
Correlation between the increase in length of the Calcaneum to the increase in interfacet distance is looked for in this study.There was no significant correlation between the length of the Calcaneum and the interfacet distances.The presence of Calcaneal spur is observed in 47% of the bones in this study.Two types of spurs are noted, namely the Dorsal Calcaneal spur and Plantar or inferior Calcaneal spur with an incidence of 8% and 27% A single fused articular facet for Talus in the Calcaneum is reported in 3.6% of bones in the present study, which is much higher than the study by Muthukumaravel et al (0.42%) [7].This type of Calcaneum is not reported in Priya et al [9] study.In the present study, the anterior and middle Talar facets in Type B Calcaneii are fused in two different formats.In Type B1, they are fused completely (37%).In Type B2, there is a notch between the two facets (32%).The results are similar to that of a study by Jha and Singh [10], however the incidence of Type B2 is much higher in the present study than by Jha and Singh [10] study (11.87%).
In the present study, the anterior and middle interfacet distance is less than 2mm in 11.8% of bones and in 9.1% of Calcaneum, the distance ranged between 2mm to 5mm.The results are similar to the results of the study by Bhanu Sudha Parimala N et al [11].Therefore, in the present study, the interfacet distance between anterior and middle facet is less than 5mm in majority of the Calcaneum.Bruckner's [3] hypothesis and the findings of Francine D V [4] have stated that Talar facet morphology is the key for subtalar joint stability.The three facet morphology of the Calcaneum has better stability and is less prone for arthritis.The Osseous Tripod appearance of Talus on Calcaneum offers less mobility for the Talus over the Calcaneum, thereby preventing injuries and In a study by Muthukumaravel et al [7] on 237 Calcaneum in Tamil Nadu, 33.33% of bones had three separate articular facets and 65.82% had two articular facets, with fused anterior and middle facets for Talus, that corresponds to Type A (22%) and Type B1 & B2 (69%) of present study respectively.Both the studies have similarity in the increased incidence of two Talar articular facets when compared to three Talar articular facets on the Calcaneum, however the percentage of Type B Calcaneum is more in the present study than that of the study by Muthukumaravel et al [7].
However the present study correlates well with the study by Bunning and Barnett [5] in Indian population on 78 Calcaneii, but the results is quite different on the Britain population, where the three facet morphology is more common than Various factors have been related to the development of Calcaneal spur like increase in age, obesity, ethnicity, physical activity etc. Li and Muehleman [14] have stated that the bony trabeculae in the spur were aligned in the direction of stress and not along the soft tissue traction, thereby emphasizing the hypothesis that Calcaneal spur is a skeletal response to stress during walking, running etc. Bassiouni [13] has reported that 81% of patients with osteoarthritis had Calcaneal spur when compared to the controls.Various studies have reported that patients with two facet configuration with fused anterior middle facet and separate posterior facet have lesser stability and are

CONCLUSION Conflicts of Interests: None
A thorough knowledge of pattern of Talar facets on the Calcaneum and their variations is essential for providing the best treatment in various clinical conditions.An insight into the racial differences in facet pattern is vital in carrying out surgical procedures like Calcaneal Osteotomy.Hence this study is accomplished to contribute to the subject of Anatomy enlightening the importance of variations in the normal Anatomy.
further classified into four subtypes as follows: Type B1: Anterior and middle facets are completely fused.(Figure 3) Type B2: Anterior and middle facets are fused with the presence of a notch in between them.(Figure 4) Type B3: Anterior facet is absent.Only middle and posterior facets are present.(Figure 5)

Table 1 :
Percentage of incidence of types of Calcaneum.

Table 2 :
Percentage incidence of subtypes of Type B Calcaneum.

Table 3 :
Percentage incidence of Calcaneum based on anterior and middle interfacet distance.

Table 4 :
Horizontal Length of the Calcaneum.

Table 5 :
Calcaneal spur and its correlation to the type of Calcaneum.

Table 6 :
Percentage incidence of Calcaneal spurs to the type of Calcaneum.
Comparison of Incidence of various types of Calcaneal Spur In Various Studies.moreprone for osteoarthritis.Also the literatures have cited that this type of configuration is dominant in Indians.Thereby Indians are more prone for osteoarthritis and also for the development of Calcaneal spur resulting in Heel pain.Thereby in the present study on the Calcaneum of Tamil Nadu, India, the incidence of Type B Calcaneum with fused anterior middle Talar facet and a separate posterior facet is higher and also the Calcaneal spur formation are more common in Type B Calcaneum, thereby correlating the relation of Subtalar Osteoarthritis and Calcaneal Spur formation to the Talar facet morphology on the Calcaneum.