|Year : 2019 | Volume
| Issue : 4 | Page : 1203-1206
Anatomical and biomechanical study of the lumbar interspinous ligament
Joe Iwanaga1, Emily Simonds2, Emre Yilmaz3, Maia Schumacher2, Mayank Patel2, R Shane Tubbs4
1 Seattle Science Foundation, Seattle, WA, USA; Department of Anatomy, Division of Gross and Clinical Anatomy, Kurume University School of Medicine, Kurume, Japan
2 Seattle Science Foundation, Seattle, WA, USA
3 Seattle Science Foundation, Seattle, WA, USA; Department of Trauma Surgery, BG University Hospital Bergmannsheil, Ruhr University Bochum, Bochum, Germany
4 Seattle Science Foundation, Seattle, WA, USA; Department of Anatomical Sciences, St. George's University, St. George's, Grenada
|Date of Web Publication||25-Nov-2019|
Dr. Joe Iwanaga
Seattle Science Foundation, 550 17th Avenue, James Tower, Suite 600, Seattle, WA 98122, USA
Source of Support: None, Conflict of Interest: None
Objective: The lumbar interspinous ligaments (ISLs) are thin and short fibers connecting adjacent spinous processes. However, their morphology is variably described and their biomechanics are not well understood. Therefore, the purpose of this study was to assess the anatomy and biomechanics of the lumbar ISL. Materials and Methods: Five fresh frozen cadaveric specimens were dissected posteriorly to reveal and study the lumbar ISL. Measurements of the ligaments included the anterior vertical height (length A), the posterior vertical height (length P), and the length (length H) at each lumbar level. Next, 17 lumbar vertebral levels from 6 cadaveric specimens were used for tensile strength testing. The ISLs were subjected to vertically controlled increasing manual tension. The force necessary to disrupt the ISL was recorded. Results: All the ISLs ran horizontally in an anterior–posterior direction with a slight curve. The average of length A, length P, and length H on the right sides was 9.82, 9.57, and 20.12 mm, respectively. The average of length A, length P, and length H on the left sides was 11.56, 12.01, and 21.42 mm, respectively. The mean tensile strength of the ISL was 162.33 (N) at L1/2, 85.67 (N) at L2/3, and 79 (N) at L3/4. There was a significant difference in the tensile force between L1/2 and L2/3 and L1/2 and L3/4 (P < 0.05). The ligaments became weaker with a descent along the lumbar levels. Conclusion: The results of this study might help surgeons understand pathology/trauma of the lumbar vertebral region.
Keywords: Biomechanics, cadaver, lumbar interspinous ligaments, spine, tensile strength
|How to cite this article:|
Iwanaga J, Simonds E, Yilmaz E, Schumacher M, Patel M, Tubbs R S. Anatomical and biomechanical study of the lumbar interspinous ligament. Asian J Neurosurg 2019;14:1203-6
|How to cite this URL:|
Iwanaga J, Simonds E, Yilmaz E, Schumacher M, Patel M, Tubbs R S. Anatomical and biomechanical study of the lumbar interspinous ligament. Asian J Neurosurg [serial online] 2019 [cited 2019 Dec 12];14:1203-6. Available from: http://www.asianjns.org/text.asp?2019/14/4/1203/270171
| Introduction|| |
The interspinous ligaments (ISLs) are thin and short structures connecting adjacent spinous processes. The ISLs are well vascularized and contain sensory nerves, particularly on their dorsal and lateral surfaces. These ligaments originate partly from the ligamenta flava, partly from the corresponding vertebral laminae, and partly from the caudal aspect of the spinous process. The lumbar ISLs are thicker and tend to be more rhombus and quadrilateral in nature and often occur in pairs. The lumbar ISLs are usually depicted with a fiber direction running obliquely or horizontally in an anterior–posterior direction from the superior margin of the caudal spinous process to the cranial spinous process., However, there are multiple depictions and various conflicting descriptions of the ISL.
The ISLs are part of the posterior ligamental complex, and they act as stabilizers of the spine and help to limit spine flexion. As the biomechanics of the ISL have scantly been studied, the current anatomical study was performed with the hopes of improving our knowledge of the biomechanics of the lumbar ISL.
| Materials and Methods|| |
Five fresh frozen, cadaveric specimens (three males and two females) were dissected in the prone position. The mean age at death was 77.2 ± 8.7 years (range, 63–88 years). A skin incision was made in the midline of the back, and the lumbar back muscles were removed to expose the spinous processes, vertebral laminae, pedicles, and transverse processes of T12 to the first sacral segment. With an electric bone saw (Stryker, Kalamazoo, Michigan, USA), the entire lumbar spines with T12 and S1 were removed and divided into two distinct pieces. The posterior half consisted of the zygapophyseal joints, transverse and spinous processes, capsular ligaments, ligamenta flava, and ISLs. The spinal cord, roots, and spinal meninges were removed. Three measurements were made – the anterior vertical height at the base of the spinous process (length A), the posterior vertical height at the junction of the ISL and supraspinous ligament (length P), and the horizontal length (length H) on each lumbar level [Figure 1]. All the measurements were made using a microcaliper (Mitutoyo, Kanagawa, Japan) with a resolution of 0.01 mm and an accuracy value of ± 0.025 mm.
|Figure 1: Measurements on a lateral view of the left interspinous ligament (arrows). A – Anterior vertical length; P – Posterior vertical length; H – Horizontal length|
Click here to view
Next, 17 lumbar vertebral levels from 6 cadaveric specimens (two males and four females) were used for tensile strength testing. The mean age at the time of death was 71.6 ± 16.2 years (range, 46–91 years). Six ISLs from the L1/2 vertebral level, six ISLs from the L2/3 vertebral level, and five ISLs from L3/4 intervertebral level were used. One L3/4 ISL from a 46-year-old male was not used due to damage to this level. A tensile testing device (M2-200, Mark-10 Corporation, USA) was used to measure the tensile strength of the ISL. The lumbar posterior column was resected using the aforementioned method. The ligamenta flava, supraspinous ligaments, and zygapophyseal joint capsules were cut so that only the ISLs connected the adjacent lumbar vertebrae. The middle of the spinous processes was held with bony clamps to fix specimens to the tensile force testing device. The ISLs were then subjected to vertically controlled increasing manual tension. The failure force (N) was recorded for each ISL [Figure 2].
|Figure 2: The failure force was recorded at failure of the interspinous ligament (arrow). SSL – Supraspinous ligament|
Click here to view
All the measurements were made by two clinical anatomists (J. I. and R. S. T.). The measurement was performed three times by each observer and then was averaged.
| Results|| |
All the ISLs ran horizontally in an anteroposterior direction and were slightly curved [Figure 3] and [Table 1]. The average of length A, length P, and length H on the right sides was 9.82 ± 2.85 mm (range, 4.52–16.78 mm), 9.57 ± 3.03 mm (range, 4.51–18.78 mm), and 20.12 ± 12.13 mm (range, 9.23–25.09 mm), respectively. The average of length A, length P, and length H was 11.56 ± 2.32 mm (range, 6.40–18.70 mm), 12.01 ± 2.23 mm (range, 6.54–17.73 mm), and 21.42 ± 2.97 mm (range, 13.96–29.80 mm), respectively, on the left sides. Lumbar level, side, or sex were not the predictors of the lengths A, P, or H of the ISL (P > 0.05).
The mean tensile strength of the ISL was 162.33 ± 38.36 N (range, 126–230 N) at L1/2, 85.67 ± 37.25 N (range, 54–165 N) at L2/3, and 79.00 ± 27.31 N (range, 41–123 N) at L3/4. There was a significant difference in the tensile strength between L1/2 and L2/3 and L1/2 and L3/4 (P < 0.05). The ligaments became weaker with a descent along the lumbar levels. All the ISLs were torn at the middle part of the ligament.
| Discussion|| |
The ISL has been said to help anchor the thoracolumbar fascia to the spine  and to be composed of a mix of collagen and elastic fibers. As the ISL ages, the fibers become thicker, and in some cases, they can ossify resulting in pain and, perhaps, instability.,, There is a fan-like arrangement of collagen in this ligament which runs parallel to the spinous process so that the ISL is thought to offer limited resistance to flexion of the lumbar spine. Fick  described the ISL as square plates with distinguishable anterior, posterior, superior, and inferior margins. This author suggested that these ligaments could be divided into several laminae, each showing openings filled with blood vessels and fat. Richter  was the first to describe the ISL as a broad membrane composed of irregular fibers. However, there have been various and conflicting descriptions of the direction of the ISL including the following: posteroinferior direction from the base and lower margin of the lower spinous process to the upper margin and tip of the lower spinous process, posterosuperior to anteroinferior fiber direction, and traveling vertically from the inferior margin of the spinous process above to the superior margin of the spinous process below. Tandler  described the fiber bundles in the ISL as forming a U-shaped pattern open dorsally. In D'Alton and D'Altons' view, the ISLs are composed of diagonally arranged fiber bundles which, when the back is flexed, separate radially and often reveal free openings between fiber bundles. In the present study, the direction of the fibers was parallel to the spinous processes with a slight curvature.
Clinically, Neumann et al. found that when the interspinous distance in the lumbar region exceeds 7 mm suggesting disruption of the ISL, further radiological investigation is warranted to rule out instability. Jang and Park  measured the interspinous spaces and demonstrated that the widest ISL was found at the levels of L3/L4 and L4/L5, whereas the greatest length was found at the L1 level, and these findings are consistent with our results.
Debate regarding the function of the ISL began as early as the 19th century by such authors as D'Alton and D'Alton  and Richter. Iida et al. found that the mechanical strength of the lumbar ISL decreases with age. Kotani et al. conducted tensile strength testing of the ISL in sheep but confounded their data by including the adjacent supraspinous ligaments. Adams et al. indicated that the ISL and supraspinous ligaments contribute about 19% of resistance to flexion of the lumbar spine. In the present study, the ISL was isolated from the supraspinous ligaments. Even though many biomechanical studies of the human spine have been performed,,, to our knowledge, a study dedicated to the tensile strength of the human lumbar ISL has not been previously performed. We found that the mean tensile strength of the ISL was 162.33 ± 38.36 N at L1/2, 85.67 ± 37.25 N at L2/3, and 79.00 ± 27.31 N at L3/4. Interestingly, the tensile strength of the L1/2 ISL was significantly greater than that of the L2/3 and L3/4 ligaments. For comparison, the tensile strengths of the anterior longitudinal ligament and posterior longitudinal ligament are 340 N and 180 N, respectively., In addition, our study found that the ISL became weaker with a descent along the lumbar levels.
Several studies have reported the clinical significance of the ISL including that ligamentous damage might play a crucial role in increased nociception, for example, low back pain and disc herniation.,,,,,,, Understanding the difference in tensile strength of the ISL for the various lumbar levels, as found in our study, might aid in developing better surgical fixation devices or help predict the level of injury with hyperflexion injuries due to trauma.
We have studied the anatomy and biomechanics of the ISL. The results of this study could help better understand the pathology of the lumbar vertebral region and help develop better treatments of this area based on these data.,,
| Conclusion|| |
The results of this study might help in our understanding of pathology/trauma of the lumbar vertebral region by better appreciating the anatomy and biomechanics of the ISL.
The authors would like to thank all who donated their bodies to advance medical research and education.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Scapinelli R, Stecco C, Pozzuoli A, Porzionato A, Macchi V, De Caro R. The lumbar interspinous ligaments in humans: Anatomical study and review of the literature. Cells Tissues Organs 2006;183:1-1.
Standring S. Gray's Anatomy E-Book: The Anatomical Basis of Clinical Practice. London: Elsevier Health Sciences; 2015.
Mori K, Yoshii T, Hirai T, Iwanami A, Takeuchi K, Yamada T, et al.
Prevalence and distribution of ossification of the supra/interspinous ligaments in symptomatic patients with cervical ossification of the posterior longitudinal ligament of the spine: A CT-based multicenter cross-sectional study. BMC Musculoskelet Disord 2016;17:492.
Hukins DW, Kirby MC, Sikoryn TA, Aspden RM, Cox AJ. Comparison of structure, mechanical properties, and functions of lumbar spinal ligaments. Spine (Phila Pa 1976) 1990;15:787-95.
Barros EM, Rodrigues CJ, Rodrigues NR, Oliveira RP, Barros TE, Rodrigues AJ Jr. Aging of the elastic and collagen fibers in the human cervical interspinous ligaments. Spine J 2002;2:57-62.
Fick R. Handbook of anatomy and mechanics of the joints. In: Handbook of human anatomy. Verlag von Gustav Fischer: Jena; 1904.
Richter T. Encyclopaedia of anatomy; Leipzig, Baumgärtner; 1836.
Rissanen PM. The surgical anatomy and pathology of the supraspinous and interspinous ligaments of the lumbar spine with special reference to ligament ruptures. Acta Orthop Scand Suppl 1960;46:1-00.
Kajava Y. Human anatomy. Porvoo Finland; WSOY; 1922.
Woerdeman MW. Standart atlas of human anatomy. Stuttgart; Medica Verlag; 1955.
Tandler J. Textbook of Systematic Anatomy. Leipzig: Vogel; 1919.
D'Alton E. Handbook of Human Anatomy: The Anatomy of Movement Tools. Leipzig: Kretzschmar; 1850.
Neumann P, Wang Y, Kärrholm J, Malchau H, Nordwall A. Determination of inter-spinous process distance in the lumbar spine. Evaluation of reference population to facilitate detection of severe trauma. Eur Spine J 1999;8:272-8.
Jang D, Park S. A morphometric study of the lumbar interspinous space in 100 stanford university medical center patients. J Korean Neurosurg Soc 2014;55:261-6.
Iida T, Abumi K, Kotani Y, Kaneda K. Effects of aging and spinal degeneration on mechanical properties of lumbar supraspinous and interspinous ligaments. Spine J 2002;2:95-100.
Kotani Y, Cunningham BW, Cappuccino A, Kaneda K, McAfee PC. The effects of spinal fixation and destabilization on the biomechanical and histologic properties of spinal ligaments. An in vivo
study. Spine (Phila Pa 1976) 1998;23:672-82.
Adams MA, Green TP, Dolan P. The strength in anterior bending of lumbar intervertebral discs. Spine (Phila Pa 1976) 1994;19:2197-203.
Iwanaga J, Sardi JP, Laws T, Chapman JR, Oskouian RJ, Tubbs RS. Anatomy of alar ligament part III: Biomechanical study. World Neurosurg 2017;107:1012-5.
Yoganandan N, Bass CR, Voo L, Pintar FA. Male and female cervical spine biomechanics and anatomy: Implication for scaling injury criteria. J Biomech Eng 2017;139:0545021-5.
Luo J, Annesley-Williams DJ, Adams MA, Dolan P. How are adjacent spinal levels affected by vertebral fracture and by vertebroplasty? A biomechanical study on cadaveric spines. Spine J 2017;17:863-74.
Tkaczuk H. Tensile properties of human lumbar longitudinal ligaments. Acta Orthop Scand 1968;39 Suppl 115:1-69.
Bogduk N. Clinical Anatomy of th Lumbar Spine and Sacrum. 3rd
ed. New York: Churchilll Livingstone; 1997.
Keorochana G, Taghavi CE, Tzeng ST, Morishita Y, Yoo JH, Lee KB, et al.
Magnetic resonance imaging grading of interspinous ligament degeneration of the lumbar spine and its relation to aging, spinal degeneration, and segmental motion. J Neurosurg Spine 2010;13:494-9.
Keorochana G, Taghavi CE, Tzeng ST, Lee KB, Liao JC, Yoo JH, et al.
MRI classification of interspinous ligament degeneration of the lumbar spine: Intraobserver and interobserver reliability and the frequency of disagreement. Eur Spine J 2010;19:1740-5.
Kohler R. Contrast examination of the lumbar interspinous ligaments; preliminary report. Acta radiol 1959;52:21-7.
Kong MH, Morishita Y, He W, Miyazaki M, Zhang H, Wu G, et al.
Lumbar segmental mobility according to the grade of the disc, the facet joint, the muscle, and the ligament pathology by using kinetic magnetic resonance imaging. Spine (Phila Pa 1976) 2009;34:2537-44.
Maes R, Morrison WB, Parker L, Schweitzer ME, Carrino JA. Lumbar interspinous bursitis (Baastrup disease) in a symptomatic population: Prevalence on magnetic resonance imaging. Spine (Phila Pa 1976) 2008;33:E211-5.
Sartoris DJ, Resnick D, Tyson R, Haghighi P. Age-related alterations in the vertebral spinous processes and intervening soft tissues: Radiologic-pathologic correlation. AJR Am J Roentgenol 1985;145:1025-30.
Tsao H, Tucker KJ, Coppieters MW, Hodges PW. Experimentally induced low back pain from hypertonic saline injections into lumbar interspinous ligament and erector spinae muscle. Pain 2010;150:167-72.
Zhang JF, Liu C, Yu HJ, Ma JJ, Cai HX, Fan SW. Degenerative changes in the interspinous ligament. Acta Orthop Traumatol Turc 2014;48:661-6.
Creze M, Soubeyrand M, Yue JL, Gagey O, Maître X, Bellin MF. Magnetic resonance elastography of the lumbar back muscles: A preliminary study. Clin Anat 2018;31:514-20.
Maddali P, Moisi M, Page J, Chamiraju P, Fisahn C, Oskouian R, et al.
Anatomical complications of epidural anesthesia: A comprehensive review. Clin Anat 2017;30:342-6.
Ghannam M, Jumah F, Mansour S, Samara A, Alkhdour S, Alzuabi MA, et al.
Surgical anatomy, radiological features, and molecular biology of the lumbar intervertebral discs. Clin Anat 2017;30:251-66.
[Figure 1], [Figure 2], [Figure 3]