Morphometric analysis of the anterior cruciate ligament: South Indian cadaveric study

Vetrivel Chezian Sengodan; GL Jyothilakshmi; Marimuthu Sivagnanam; PA Shree Shyam Sundar

doi:10.4103/NJCA.NJCA_114_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 11 | Issue : 4 | Page : 222-226

Morphometric analysis of the anterior cruciate ligament: South Indian cadaveric study

Vetrivel Chezian Sengodan¹, GL Jyothilakshmi², Marimuthu Sivagnanam³, PA Shree Shyam Sundar⁴
¹ Director and Professor, Institute of Orthopaedics and Traumatology, Coimbatore Medical College Hospital, Coimbatore, The Tamil Nadu Dr. MGR Medical University, Chennai, Tamil Nadu, India
² Associate Professor, Department of Anatomy, Rajarajeshwari Medical College and Hospital, Bengaluru, Karnataka, India
³ Associate Professor, Institute of Orthopaedics and Traumatology, Coimbatore Medical College Hospital, Coimbatore, The Tamil Nadu Dr. MGR Medical University, Chennai, Tamil Nadu, India
⁴ Junior Resident, Institute of Orthopaedics and Traumatology, Coimbatore Medical College Hospital, Coimbatore, The Tamil Nadu Dr. MGR Medical University, Chennai, Tamil Nadu, India

Date of Submission	03-Jul-2022
Date of Decision	08-Aug-2022
Date of Acceptance	01-Sep-2022
Date of Web Publication	29-Oct-2022

Correspondence Address:
Vetrivel Chezian Sengodan
16H, Housing Unit, Mettupalayam, Coimbatore - 641 301, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NJCA.NJCA_114_22

Abstract

Background: The most often damaged ligament in the knee joint is the anterior cruciate ligament (ACL). Reconstruction surgery is the ideal option which requires morphometric understanding of ACL. The aim of the present study is to determine the length and width of ACL in the knee joint in the South Indian population. Methodology: The study was conducted from August 2020 to July 2021 during a 1-year period. We selected participants with no evident macroscopic abnormalities of the knee joints, between the ages of 27 years and 55 years of both genders. For the study, 50 knee joints from 29 cadavers that fulfilled the above requirements were dissected and the ACL was measured for its length and width in the center point in between bony attachments with digital vernier caliper. Results: The mean length of the ACL was found to be 29.73 mm with standard deviation of 2.32, and the mean width of the ACL was found to be 11.15 mm with standard deviation of 1.07. Conclusion: The present study will add to the existing knowledge on the morphometry of the ACL. This study would be helpful in selecting grafts for surgical reconstruction of the ACL.

Keywords: Anterior cruciate ligament, knee joint, morphometry

How to cite this article:
Sengodan VC, Jyothilakshmi G L, Sivagnanam M, Shree Shyam Sundar P A. Morphometric analysis of the anterior cruciate ligament: South Indian cadaveric study. Natl J Clin Anat 2022;11:222-6

How to cite this URL:
Sengodan VC, Jyothilakshmi G L, Sivagnanam M, Shree Shyam Sundar P A. Morphometric analysis of the anterior cruciate ligament: South Indian cadaveric study. Natl J Clin Anat [serial online] 2022 [cited 2023 Feb 6];11:222-6. Available from: http://www.njca.info/text.asp?2022/11/4/222/359869

Introduction

There are two cruciate ligaments in the knee joint, the anterior cruciate ligament (ACL) and posterior cruciate ligament. The ACL is an intra-articular, extrasynovial ligament. It is attached to two bones, the tibia and the femur. The tibial attachment is to the anterior intercondylar region of the tibia, immediately anterior and somewhat lateral to the medial intercondylar tubercle.^[1],[2],[3] It rises posterolaterally and attaches to the posteromedial portion of the lateral femoral condyle.^[1],[2],[3] The ACL has two bundles, the anteromedial and the posterolateral bundle based on their tibial insertion.^[1],[4]

The knee ligament that sustains injury most frequently is the ACL. ACL injuries are estimated to account for over 60% of all knee injuries. Direct, indirect, and noncontact contact are the three basic ways that the ACL can be injured.^[5] ACL injuries most often result from noncontact injuries that occur when runners abruptly shift directions while running.^[6]

There are various functions of the ACL, the major function being preventing anterior translation of the tibia on the femur as one of the major stabilizers of the knee. At 30° and 90° of knee flexion, the ACL exerts 85% of the force that prevents anterior tibial displacement. While the posterolateral band of the ligament primarily contributes to stability in extension, the anteromedial band is more crucial in flexion for limiting anterior tibial translation.^[7] Other functions include giving the knee rotational stability in both the frontal and transverse planes,^[7],[8],[9] the restriction of varus/valgus stresses^[10] and as the knee nears terminal extension, the ACL improves the screw-home mechanism.^[11]

In complete tear of the ACL, it does not heal with repair leading to knee instability and the onset of early osteoarthritis.^[12] Hence, reconstruction of the ACL is vital whenever it is injured.^[13] Anatomical understanding of the ACL is more crucial for selecting a suitable graft with the right size and for a satisfactory outcome to prevent complications after replacement surgery. Technical error, particularly improper graft size estimation, is one of the major reasons treatments fail.^[14] It is therefore imperative that surgeons need to have a thorough understanding of the anatomy, morphology, and measurements of the ACL which will enable them to determine the size of the graft to be used in the reconstruction.

Many studies have been conducted in the west, but studies done in India are relatively few in number. In South India, there have only been a handful of studies conducted so far. This study's objective was to ascertain the morphometry of the ACL in the South Indian population which will help the surgeons in understanding the variations in ACL morphometry, thereby guiding them in the management of ACL injuries in this population.

Materials and Methods

The study was conducted in the Department of Anatomy and Institute of Orthopaedics and Traumatology, Coimbatore Medical College Hospital, Coimbatore, India, from August 2020 to July 2021 during 1 year after obtaining the institutional ethical committee clearance (No. 527/2021). Cadavers whose age was between 27 and 55 years (average age –38 years) of both sexes were selected for this study of which nine were female and 20 were male. Skeletally mature cadavers without injury to the knee joint were included in the study. Skeletally immature cadavers and mutilated and decomposed cadavers were excluded from our study. Twenty-nine cadavers were chosen for our study group of which 50 knee joints were dissected.

The knee dissection was carried out in accordance with Cunningham's textbook of anatomy.^[15] The skin, soft tissues, muscles, and articular capsules were dissected [Figure 1]. The soft tissues were stripped except for the ligaments and menisci. The attachment of the ACL in the tibia and femur was identified by careful dissection [Figure 2]. The length of the ACL was measured from its femoral insertion to its tibial insertion in full knee flexion [Figure 3] and the width of the ligament was measured at their center point in between bony attachments of ACL [Figure 4] which were marked with skin marker with digital vernier caliper and were photographed [Figure 5]. Each parameter was measured individually by two observers, and their average was recorded.

Figure 1: Photograph showing knee joint midline skin incision

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Figure 2: Photograph showing the left knee joint after dissection with ACL attachment marked by pins. ACL: Anterior cruciate ligament

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Figure 3: Photograph showing the measurement of the length of ACL using a digital vernier caliper in full knee flexion. ACL: Anterior cruciate ligament

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Figure 4: Photograph showing the measurement of the width of ACL using a digital vernier caliper. ACL: Anterior cruciate ligament

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Figure 5: Photograph showing the marking of center point of the middle third using a surgical skin marker

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Results

In all cadavers, the length and width of ACL were recorded and tabulated [Table 1].

Table 1: Length and width of the anterior cruciate ligament in cadavers

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In our study, the overall maximum length recorded was 34.11 millimeters (mm) and the minimum length recorded was 24.33 mm, and the mean length of ACL was found to be 29.73 mm [Table 2].

Table 2: Descriptive statistics of numerical variables - Overall

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On the right side, the maximum length of ACL recorded was 34.11 mm and the minimum length recorded was 24.33 mm, and the mean length was found to be 30.09 mm [Table 3]. On the left side, the maximum length of ACL recorded was 32.8 mm and the minimum length recorded was 25.03 mm, and the mean length was found to be 29.43 mm [Table 3].

Table 3: Descriptive statistics of numerical variables - Gender wise and sidewise

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The maximum width recorded was 13.3 mm and the minimum width recorded was 8.4 mm, and the mean width of ACL was found to be 11.15 mm [Table 2].

On the right side, the maximum width recorded was 13.3 mm and the minimum width recorded was 9.23 mm, and the mean width was found to be 11.31 mm [Table 3]. On the left side, the maximum width recorded was 12.90 mm and the minimum width recorded was 8.40 mm, and the mean width was found to be 11.08 mm [Table 3].

The mean length, width is compared between males and females using t-test for equality of means. There is no significant difference that could be found between males and females with respect to the length or width of ACL [Table 4].

Table 4: t-test for equality of means of anterior cruciate ligament length and width in males and females

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Paired sample t-test is conducted to find a significant difference between right and left length. The t-value is 2.375 and the corresponding P is 0.028 (P < 0.05). That is a significant difference could be found between right and left length. Whereas with respect to the right and left widths, no significant difference could be found (t = 1.145, P > 0.05).

Discussion

Young and active people are more prone to ACL injuries. According to reports, women practicing the same sport run a risk that is 2–8 times higher than that of men.^[16],[17]

Reconstruction surgeries are used to repair ACL injuries, and here is where morphometric studies are helpful. The nonanatomic attachments were mostly to blame for the reconstructive procedures' failure to reestablish normal joint kinetics. Understanding the morphometry of the ACL and assisting in anatomic reconstruction are both made possible by the morphometric analysis of the ACL of the knee joints.

ACL intra-articular length is essential for improved knee joint stability. Increased mobility and graft impingement will result from an ACL that is longer than usual, whereas an ACL that is shorter than normal will lose its capacity to maintain anteroposterior stability. The width of the ACL is crucial in limiting knee laxity. Less ACL width was attributed in part to higher anterior knee laxity.^[18]

According to Zantop et al., screw fixation may be impossible because a long graft may stick out from the tunnel and a small graft might be buried. Therefore, while selecting the graft, consideration should be given to the ligaments' thickness and length.^[19]

The typical length and breadth of the ACL are 38 mm and 11 mm, respectively, according to Gray's anatomical textbooks.^[1] Comparing these to the results of this study, the length was higher while the width correlates with the study.

Girgis et al. in their study at Cornell University, USA, found the length of ACL to be 31–38 mm.^[2] Odensten and Gillquist, USA, showed that the ACL in 33 cadaveric knee joints measured 31 mm in length.^[20] Iriuchishima et al., USA, observed that the ACL's length was 32.28 mm.^[21] The average radiographic length of the ACL was reported to be 40.6 ± 3.6 mm, by Van Zyl et al. in their study at Pretoria, South Africa.^[22] Comparing these numbers to the results of the current study, they were much higher.

The results of this study were compared with that of the literature as shown in [Table 5] and [Table 6].

Table 5: Length and width of the anterior cruciate ligament in Western studies

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Table 6: Length and width of the anterior cruciate ligament in Indian studies

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Among Indian studies, Lalwani et al. in their study at Bhopal, India, found the mean length of ACL was found to be 30.79 mm^[23] which correlates with our study.

Geetha Rani et al. in their study in 2019 at Bengaluru, India, determined the ACL's length and width to be 37.14 ± 3.916 mm and 5.2 ± 1.094 mm, respectively.^[24] Comparing these numbers to the results of the current study, the length was much higher but the width was lesser.

Saxena et al. in their study at Kasturba Medical College, Manipal University, Manipal, Karnataka, determined the ACL's length and width to be 32.5 mm ± 4.33 and 9.38 mm ± 1.58,^[25] respectively, the findings of which correlates with our study.

Conclusion

The ACL is crucial to the stability of the knee joint. The ACL is more prone to injury and morphometric study is very important in the reconstruction of ACL. This study showed the morphometric parameter of the ACL in the South Indian population. This can aid surgeons in making crucial choices about the size of the graft during ACL reconstruction surgeries. The study will be useful in determining the correct length of the graft to avoid a reconstruction that is excessively stiff or lax during different ranges of motion. The study can benefit the surgeon in gaining a better understanding of the local population ACL morphometry, which differs greatly from that of Western nations. As a result, future decision-making will be more successful and less likely to fail.

Limitations

Large sample size and multicentric study are necessary to confirm our measurements.

Acknowledgments

The authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase Humankind's overall knowledge and then improve patient care. Therefore, these donors and their families deserve our highest gratitude.^[26]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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