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| ORIGINAL ARTICLE |
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| Year : 2018 | Volume
: 9
| Issue : 2 | Page : 132-136 |
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Morphometric analysis of vascular foramina in Indian dry calcaneus and its clinical applications
Naina S Wakode1, Santosh L Wakode2, Babita Kujur1
1 Department of Anatomy, AIIMS, Bhubaneswar, Odisha, India
2 Department of Physiology, AIIMS, Bhopal, Madhya Pradesh, India
| Date of Web Publication | 20-Jun-2018 |
Correspondence Address:
Santosh L Wakode
Department of Physiology, AIIMS, Bhopal, Madhya Pradesh
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jnsbm.JNSBM_35_18
 Abstract | | |
Introduction: The calcaneus is the largest tarsal bone of hindfoot and its fractures are most difficult to treat. The knowledge about the vascular foramina is important to understand the pathogenesis and its surgical management. Aim: The scope of the present study is to generate morphological data in the form of location, size, and numbers of vascular foramina of calcaneus, as well as the length of calcaneus, to generate foramina index and their frequency of distribution in the dry calcaneus. Materials and Methods: The present study consisted of 118 (59 right and 59 left) dried human calcaneus. The bones were macroscopically studied for vascular foramina with respect to its size, location, numbers, and foramina index were determined. The data collected were statistically analyzed. Results: A total of 3112 vascular foramina were found on the right and left calcaneus. Kruskal–Wallis test showed that there was a statistically significant difference in a total number of vascular foramina over different surfaces of calcaneus (P ≤ 0.00001). Mann–Whitney U-test done for post hoc analysis proved that the total number of the vascular foramina observed on the lateral surface was significantly greater than the vascular foramina detected over other surfaces. The lateral and medial surfaces were presented with maximum number of foramina while posterior surface showed least number of the vascular foramina. Conclusion: We believe that the present study has provided additional data on vascular foramina of calcaneus in the Indian population, which will be an anatomical guide to surgical interventions involving the calcaneus bone. Keywords: Calcaneus, foramina index, fractures, graft, morphometry, vascular foramina
How to cite this article:
Wakode NS, Wakode SL, Kujur B. Morphometric analysis of vascular foramina in Indian dry calcaneus and its clinical applications. J Nat Sc Biol Med 2018;9:132-6 |
How to cite this URL:
Wakode NS, Wakode SL, Kujur B. Morphometric analysis of vascular foramina in Indian dry calcaneus and its clinical applications. J Nat Sc Biol Med [serial online] 2018 [cited 2021 Mar 2];9:132-6. Available from: http://www.jnsbm.org/text.asp?2018/9/2/132/234727 |
| Introduction | |  |
The calcaneus is the largest tarsal bone of hindfoot and it is also called as the calcaneum. The calcaneus is roughly box-shaped bone sitting below the talus, and its anterior aspect is inclined cranially. It projects posteriorly to form the core of the heel.[1] It articulates with the talus superiorly and with cuboid anteriorly, and shares a joint space with the talonavicular joint, appropriately called the talocalcaneonavicular joint.[1],[2],[3],[4],[5] The calcaneus transfers most of the body weight from the lower limb to the ground. Calcaneal fractures have long been recognized as a source of significant disability and remain one of the most difficult articular fractures to treat. Historically, there has been debate over the best approach for treating these fractures.[2],[3],[4],[5]
The main blood supply to calcaneus is through medial calcaneal and lateral calcaneal arteries branches of the posterior tibial artery. Only 10% of blood supply to calcaneus is from sinus tarsi artery.[6],[7] Calcaneus fractures account for 2% of all fractures; however, they make up 60% of fractures of the mid-foot bones.[8] Out of these 60%, nearly 80% to 90% of the calcaneal fractures are found in middle-aged male industrial workers. Several authors have reported that the calcaneus fractures can be actually severe. Treatment often involves surgery to restore the normal anatomy of the calcaneus and its mobility. However, despite the appropriate treatment, some fractures may result in long-term complications, such as pain, swelling, loss of motion, and arthritis.[9] The rehabilitation to these fractures can take from 9 months to several years, which implicates great economic burden on society.[10],[11],[12] The larger or smaller foramina (openings) present on bones for the entrance of blood vessels is known as the nutrient foramina or vascular foramina.
Knowledge of anatomical location and size of vascular foramen is necessary to ensure safe surgical intervention in the form of percutaneous insertion of screw in the calcaneus for anatomical correction. Calcaneal insufficiency avulsion fractures are seen in the patients with diabetes mellitus.[12] As calcaneus is the most commonly injured tarsal in the foot,[13] their morphometric study in the form of location and size of vascular foramina is very important. However, there is scarcity in the literature regarding the same and literature search of PubMed failed to yield any such study regarding vascular foramina of calcaneus.
The scope of the present study is to generate morphological data in the form of location, size, and numbers of vascular foramina and the length of calcaneus, and to generate foramina index and their frequency of distribution in the dry calcaneus of the Indian population. The study also aims to determine the less vascular surface of calcaneus depending on the distribution of vascular foramina and its clinical application.
| Materials and Methods | | |
After approval of Institutional Ethics Committee, the present study was carried on 118 (59 right and 59 left) dried human calcaneus. All bones were obtained from the osteology section of the Department of Anatomy, All India Institute of Medical Sciences, Bhubaneswar, India, and other nearby medical institutes of same region. Bones with gross pathological deformities and fracture were excluded from the study. The age and gender of bones were not determined. All the bones were macroscopically observed for the number, location, and size of the nutrient foramina. A magnifying lens was used to observe the foramina. The vascular foramina [Figure 1]a and [Figure 1]b were identified by the presence of a well-marked groove and canal which were raised above the surface of the bone. The K-wire of diameter 1 mm was passed through each foramen to confirm their patency as well as the size. The foramina which allowed the 1-mm K-wire were noted as more than 1 mm in diameter, and those foramina not allowing the entry of 1-mm K-wire were noted as <1 mm in diameter. Distance from the most posterior point of calcaneus to the largest vascular foramina present on the medial and lateral surfaces was noted and was labeled as M1 and L1, respectively [Figure 1]a and [Figure 1]b. | Figure 1: (a) Distance from the most posterior point of calcaneus to the largest vascular foramina present on the medial surface of the calcaneus labeled as M1. Other vascular foramina are shown in dotted circle. (b) Distance from the most posterior point of calcaneus to the largest vascular foramina present on the lateral surface of the calcaneus labeled as L1. Other vascular foramina are shown in dotted circle. (c) Length of calcaneus with the help of vernier caliper
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The foramina index of the medial and lateral surface of the calcaneus was calculated. The formula for foramina index is expressed as I = DF/TL×100, where I is the foramina index, DF is the distance from the posterior-most end of the calcaneum to largest vascular foramina of medial and lateral surface [Figure 1]a and [Figure 1]b, and TL is the total length of calcaneum from the most anterior to most posterior point of the bone [Figure 1]c. Frequency histogram was drawn from foramina index of calcaneus showing most distributed area of largest foramina (>1 mm diameter) on medial and lateral surface of the calcaneus [Figure 2], [Figure 3], [Figure 4], [Figure 5]. All measurements were noted with the help of digital vernier caliper with an accuracy of 0.01 mm. All readings were done by same person to avoid interobserver error. | Figure 2: Frequency histograms of the right medial wall foramina index (right M-1) showed that majority (26.17%) were located with foramina index of 50%–60%
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 | Figure 3: Frequency histograms of the right lateral wall foramina index (right L-1) showed that majority (27.56%) were located with foramina index of 30%–40%
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 | Figure 4: Frequency histograms of the left medial wall foramina index (left M-1) showed that majority (29.09%) were located with foramina index of 40%–50%
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 | Figure 5: Frequency histograms of the left lateral wall foramina index (left L-1) showed that majority (26.06%) were located with foramina index of 30%–40%
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Statistical analysis was done using data analysis tool pack in built in micro soft excel. The unpaired Student's t-test and Mann–Whitney U-test was applied to find out the statistical difference between the parameters of right and left of calcaneus bones. Kruskal–Wallis test was used to analyze the number of vascular foramina on various surfaces of the calcaneus, subsequent by series of the Mann–Whitney U-test for post hoc analysis.
| Results | | |
Vascular foramina were observed over the anterior, posterior, superior, inferior, medial, and lateral surfaces of the calcaneus. The total numbers and percentage distribution of vascular foramina are shown in [Table 1]. The lateral and medial surfaces were presented with maximum number of foramina followed by the inferior, superior, and anterior. Posterior surface of the both sides showed the least number of the vascular foramina [Table 1] and [Table 2]. | Table 1: The distribution (spreading) of nutrient foramina on different surfaces between right (n=59) and left (n=59) calcaneus
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 | Table 2: Minimum and maximum number of foramina on different surfaces of calcaneus
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Kruskal–Wallis test showed that there was a statistically significant difference in a total number of vascular foramina between the different surfaces of calcaneus, right side (H statistic = 162.09, P ≤ 0.00001) and left side (H statistic = 189.81, P ≤ 0.00001).
Mann–Whitney U-test applied for post hoc analysis did not show any significant difference for the total number of the vascular foramina observed on the lateral and medial surface [Table 3]. Mann–Whitney U-test done for post hoc analysis proved that the total number of the vascular foramina observed on the lateral surface was significantly greater than the foramina detected on the superior, inferior, anterior, and posterior surfaces [Table 3]. | Table 3: Comparison between the nutrient foramina of lateral and other surfaces of calcaneus
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The mean calcaneal length was 74.13 ± 5.09 mm on the right side and 74.08 ± 4.68 mm on the left side. Correlation between the total length of calcaneus and largest diameter vascular foramina present on medial and lateral surfaces of the calcaneus were analyzed using Pearson's correlation coefficient. The weak positive correlation was existing between total length of calcaneus and largest vascular foramina on the medial surface of the calcaneus (right side r-0.1219, r2-0.0149 and left side r- 0.1613, r2-0.026) The weak negative correlation was existing between the total length of calcaneus and largest diameter vascular foramina on the lateral surface of the calcaneus (right side r-0.011, r2-0.0001 and left side r-0.0606, r2-0.0037).
The mean foramina index for right side medial surface was 54.69% ± 11.57% (range, 39.35%–83.82%) and for right side lateral surface was 48.43% ± 14.34% (range, 21.92%–86.35%). The mean foramina index for left side medial surface was 53.89% ± 11.35% (range, 17.18%–78.75%) and for left side lateral surface was 51.27 ± 14.49% (range, 31.005%–81.45%).
The total numbers of vascular foramina on different surface of the right and left sides of the calcaneus were 1593 and 1519, respectively [Table 1]. The 26.17% of vascular foramina were located on medial surface of right side calcaneus with a foramina index 50%–60% and 27.56% of vascular foramina were located on the right side lateral surface with a foramina index 30%–40% [Figure 2] and [Figure 3]. While 29.09% of vascular foramina were located on medial surface of left side calcaneus of with a foramina index 40%–50% and the 26.06% of vascular foramina were located on the lateral surface of the left calcaneus with a foramina index 30%–40% [Figure 4] and [Figure 5]. The total numbers of vascular foramina found in the right and left side of the calcaneus were 3112. Out of these, majority of foramina 2956 (95%) were ≤1 mm in size. Only 156 (5%) were ≥1 mm in size. The foramina ≥1 mm in size were present in 25% calcaneus specimens. Their distribution was confined mostly to lateral and medial surfaces.
| Discussion | | |
The tarsal calcaneus bone forms a part of medial and lateral longitudinal arch. The flexor retinaculum, plantar aponeurosis, and medial root of the inferior extensor retinaculum are attached to the calcaneal sulcus.[1] Both short plantar ligament and long plantar ligament are the main ligamentous support of the longitudinal arch of the foot. Hence, calcaneus plays an integral role in the hindfoot motion and gait.[14] Nearly, a one-third foot injury involves calcaneus fractures and management of these injuries is challenging due to anatomical complexity and anchorage of critical ligamentous structures. Calcaneus injuries are also complicated by a fragile soft-tissue envelope.[2],[3]
Intraarticular fractures account for the 75% and extraarticular fractures account for 25% of calcaneal fractures.[15] These typically are avulsion injuries of either the calcaneal tuberosity from the Achilles tendon, or the anterior process from the bifurcate ligament, or the sustentaculum tali. As the posterior surface of calcaneus is less vascular, knowledge of anatomical distribution of vascular foramina is necessary and important for surgeons to ensure safe surgical intervention of calcaneal fracture.[6] In the present study, morphometric analysis of vascular foramina done with 118 Indian dry calcaneus. Andermahr et al. revealed that 45% of the bone is vascularized through medial calcaneal arteries and 45% through lateral calcaneal arteries, whereas the remaining 10% is supplied by the sinus tarsi artery.[6] From the medial side, two or three vessels branch off the posterior tibial artery, penetrate the calcaneus below the sustentaculum, and supply the medial part of the posterior joint. The lateral calcaneal artery normally is a branch from the posterior tibial artery. In two of 13 specimens, this lateral supply comes from the peroneal artery.[16] The medial and lateral intraosseous arterial supply for the calcaneus is equal.[16] The present study came out with similar findings where maximum numbers of nutrient foramina were observed on medial and lateral surfaces [Table 1].
Inside the bone, there is a water-shed zone where the medial and lateral arterial supply meets in the midline. Only 10% of the blood flow is supplied by vessels in the sinus tarsi. Ischemic bone necrosis of the calcaneus may result from disruption of the sinus tarsi artery during the conventional lateral surgical approach.[5] The calcaneal infarct is seen in patients who are on the long-term steroid therapy, those who underwent heart transplantation and systemic lupus erythematosus.[17],[18] Although the calcaneus has rich vascular supply with arterial network of penetrating vessels, still the posterior calcaneus is relatively avascular region in an otherwise well-vascularized zone. These findings correlate with our study where only 2.88%–3.33% of nutrient foramina were seen on posterior surface as compared to other surfaces of the bone. This explains predisposition of posterior fractures to avascular necrosis.[17] Clinically, rupture of the larger vascular branches of the medial and lateral calcaneal artery entering through vascular foramina during the medial or lateral surgical approach for a calcaneus fracture may result in ischemic bone necrosis. Thus, bone infract may occur due to disruption of single-dominant feeding artery or due to relative avascularity of the watershed zone.[5]
When length of calcaneus observed in the present study was compared with the findings of other studies available in the literature [Table 4], we found that length of calcaneus is similar in the Indian population [19],[20] and that it differs from the Turkish population. This finding gives evidence for racial difference in calcaneal morphology. In our study, only weak correlation was seen between total length and larger diameter vascular foramen. Thus, clinicians cannot estimate the size of vascular foramina by calcaneal or heel length. | Table 4: Comparisons of total length of calcaneus between the present study and previously reported authors
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A consideration of the local vascular foramina distribution over the calcaneus may decrease the rate of complications during the operative treatment of calcaneal fractures. For the surgical management of calcaneum fractures, various approaches have been developed, but concern remains regarding the best approach for reducing and maintaining reduction of these complex fractures while minimizing the risk of complications.[21],[22],[23],[24],[25],[26] Injury to nutrient artery can occur during open or closed reduction of fractures. Hence, it is very important to have detailed knowledge of vascular foramina in orthopedic surgical procedures, such as reduction of fractures and vascularized bone microsurgery.[21],[22],[23]
The screw and plates used may worsen the traumatic devascularization of lateral and medial wall and worsen wound necrosis and may lead to malunion or nonunion. Knowledge of detailed morphometry, distribution of vascular foramina and foramina index on the wall of calcaneum can be helpful to surgeons to minimize these complications. The present study has generated some reference data regarding the proper position and distribution of vascular foramina over calcaneum. An enhanced knowledge about location and size of vascular foramina helps in understanding the various factors which play a prominent role in the development of calcaneal osteonecrosis in the patients suffering from diabetes mellitus and systemic lupus erythematosus.[12],[17]
Tanaka et al. have harvested vascularized bone graft from medial calcaneus through a fenestration of the medial aspect of the talar dome of calcaneum for the treatment of large osteochondral lesions of the medial talus. Medial calcaneus using the calcaneal branch of the posterior tibial artery was placed through a fenestration of the medial aspect of the talar bone[27] In free vascular bone grafting, the blood supply by nutrient artery is extremely important and must be preserved to promote fracture repair, as good blood supply is necessary for osteoblast and osteocyte cell survival as well as facilitating graft healing in recipient.[27] In agreement to the findings of Tanaka et al., the present study has shown maximum number of vascular foramina over lateral and medial surfaces as compared to posterior surface, thus vascularized bone graft can be taken from the medial and lateral side of the calcaneus. Finding about the vascular foramina obtained from our study will be useful to the orthopedic surgeons and clinicians who are involved in bone graft surgical procedures and are enlightening to the clinical anatomists and morphologists.
| Conclusion | | |
We believe that the present study has provided additional data on vascular foramina of calcaneus in the Indian population, which will be an anatomical guide to surgical interventions involving the calcaneus bone.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4]
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