The Lumbar Interspinous Ligaments in Humans: Anatomical Study and Review of the Literature

Ultrasound-assisted modified paramedian technique for spinal anesthesia in elderly

Background

At present, there are two techniques which are widely applied clinically; the midline and the paramedian. Both methods are difficult for clinicians when treating the elderly. The aim of this work is to explore the feasibility of an ultrasound-assisted modified paramedian technique for spinal anesthesia in the elderly. This would provide clinicians with a new and easy-to-operate technique.

Methods

A total of 150 elderly patients who were scheduled for urology surgery under spinal anesthesia in our hospital were randomly divided into three groups (n = 50): (i) midline technique group (group M), (ii) paramedian technique group (group P), and (iii) modified paramedian technique group (group PM). All spinal anesthesia were performed by the same second-year resident.

Results

Compared with groups M and P, group PM had significantly higher first-attempt success rate (P < 0.05, especially in patients aged 65-74 years), fewer attempts (P < 0.05), and higher patient satisfaction score (P < 0.05). Compared with group M, the time taken to perform spinal anesthesia and the number of needle redirections were significantly reduced in group PM (P < 0.05). There was no statistically significant difference between groups PM and P. There were also no statistically significant differences in the cases of inconsistency between ultrasound-assisted and landmark-guided location of intervertebral space, the time taken to ultrasound-assisted location, the onset time to pain block at T₁₀, the incidence of hypotension, anesthesia effect and the incidence of headache, lower back pain, or nausea and vomiting, within 24 h after surgery.

Conclusions

The modified paramedian technique in spinal anesthesia for elderly patients can significantly improve the first-attempt success rate, reduce both the number of attempts and procedure time, and minimize tissue damage during the operation. Compared with the traditional techniques, the modified paramedian technique combines the advantages of both the midline and the paramedian methods, and is easy to learn. It is worthy of further research and application.

Trial registration

Prospectively registered at the China Clinical Trial Registry, registration number ChiCTR2100047635, date of registration: 21/06/2021.

Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft tissue reconstruction and functional significance

Dicraeosaurid sauropods are iconically characterized by the presence of elongate hemispinous processes in presacral vertebrae. These hemispinous processes can show an extreme degree of elongation, such as in the Argentinean forms Amargasaurus cazaui, Pilmatueia faundezi and Bajadasaurus pronuspinax. These hyperelongated hemispinous processes have been variably interpreted as a support structure for a padded crest/sail as a display, a bison-like hump or as the internal osseous cores of cervical horns. With the purpose to test these hypotheses, here we analyze, for the first time, the external morphology, internal microanatomy and bone microstructure of the hemispinous processes from the holotype of Amargasaurus, in addition to a second dicraeosaurid indet. (also from the La Amarga Formatin; Lower Cretaceous, Argentina). Transverse thin-sections sampled from the proximal, mid and distal portions of both cervical and dorsal hemispinous processes reveal that the cortical bone is formed by highly vascularized fibrolamellar bone interrupted with cyclical growth marks. Obliquely oriented Sharpey's fibres are mostly located in the medial and lateral portions of the cortex. Secondary remodelling is evidenced by the presence of abundant secondary osteons irregularly distributed within the cortex. Both anatomical and histological evidence does not support the presence of a keratinized sheath (i.e. horn) covering the hyperelongated hemispinous processes of Amargasaurus, and either, using a parsimonious criterium, in other dicraeosaurids with similar vertebral morphology. The spatial distribution and relative orientation of the Sharpey's fibres suggest the presence of an important system of interspinous ligaments that possibly connect successive hemispinous processes in Amargasaurus. These ligaments were distributed along the entirety of the hemispinous processes. The differential distribution of secondary osteons indicates that the cervical hemispinous processes of Amargasaurus were subjected to mechanical forces that generated higher compression strain on the anterior side of the elements. Current data support the hypothesis for the presence of a 'cervical sail' in Amargasaurus and other dicraeosaurids.

Intervertebral disc degeneration relates to biomechanical changes of spinal ligaments

BACKGROUND CONTEXT

The ligamentum flavum (LF), the inter- and supraspinous ligament (ISL&SSL) and the intertransverse ligament (ITL) are relevant spinal structures for segmental stability. The biomechanical effect of degeneration and aging on their biomechanical properties remains largely unknown.

PURPOSE

The aim of this study was to assess the material properties of the ITL, ISL&SSL and LF and to correlate parameters of biomechanical function with LF-thickness, intervertebral disc (IVD) degeneration and age.

STUDY DESIGN

Biomechanical cadaveric study.

METHODS

MRI- and CT-scans of 50 human lumbar segments (Th12-L5) were used to assess the ISL (acc. to Keorochana), the grade of IVD degeneration (acc. to Pfirrmann) and to quantify LF-thickness. The ITL, ISL&SSL and LF were resected in the neutral position of the spinal segment with a specifically developed method to conserve initial strain. Ramp to failure testing was performed (0.5 mm/s) to record initial tension, slack length, stiffness and ultimate strength. The relationship between the biomechanical characteristics and age and radiological parameters were analyzed. There are no study-specific conflicts of interest and no external funding was received for this study.

RESULTS

With aging, a significant reduction in initial tension (r=-0.5, p<.01) and ultimate strength (r=-0.41, p<.01) of the LF was observed, while the effect on LF-stiffness and the characteristics of the other ligaments was non-significant. IVD-degeneration was correlated with a significant reduction in stiffness (r=-0.47, p=.001; r=-0.36, p=.01) and ultimate strength (r=-0.3, p=.04; r=-0.36, p=.01) of the LF and ISL&SSL respectively and a significant reduction in initial tension (r=-0.4, p<.01) of the LF. For the ITL, no significant correlation was observed. Comparing Pfirrman 2 to 5, this reduction was 40% to 80% for stiffness 60% to 70% for ultimate strength and 88% for initial tension of the LF. ISL&SSL-stiffness between Kerorochana grade A and D differed significantly (p=.03), while all other comparisons were non-significant (p>.05). LF-thickness did not correlate with the biomechanical properties of the LF (p>.05).

CONCLUSIONS

Aging is primarily related to biomechanical changes to the LF. IVD-degeneration is related to a relevant reduction in stiffness and ultimate strength of the LF and ISL&SSL, with a similar trend for the ITL. The ISL-specific Keorochana grading system provides only minimal biomechanical information and LF-thickness does not provide biomechanical information.

CLINICAL SIGNIFICANCE

Patient age and the degenerative state of the IVD can be used to evaluate the biomechanical characteristics of the dorsal spinal ligaments, which can be helpful in selecting the optimal surgical procedure (e.g. in decompression surgery) for a specific situation.

Anatomical and Biomechanical Study of the Lumbar Interspinous Ligament

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.

Coronal Three-Dimensional Magnetic Resonance Imaging for Improving Diagnostic Accuracy for Posterior Ligamentous Complex Disruption In a Goat Spine Injury Model

Objective

The purpose of this study was to investigate whether three-dimensional (3D) magnetic resonance imaging could improve diagnostic accuracy for suspected posterior ligamentous complex (PLC) disruption.

Materials and Methods

We used 20 freshly harvested goat spine samples with 60 segments and intact surrounding soft tissue. The animals were aged 1–1.5 years and consisted of 8 males and 12 females, which were sexually mature but had not reached adult weights. We created a paraspinal contusion model by percutaneously injecting 10 mL saline into each side of the interspinous ligament (ISL). All segments underwent T2-weighted sagittal and coronal short inversion time inversion recovery (STIR) scans as well as coronal and sagittal 3D proton density-weighted spectrally selective inversion recovery (3D-PDW-SPIR) scans acquired at 1.5T. Following scanning, some ISLs were cut and then the segments were re-scanned using the same magnetic resonance (MR) techniques. Two radiologists independently assessed the MR images, and the reliability of ISL tear interpretation was assessed using the kappa coefficient. The chi-square test was used to compare the diagnostic accuracy of images obtained using the different MR techniques.

Results

The interobserver reliability for detecting ISL disruption was high for all imaging techniques (0.776–0.949). The sensitivity, specificity, and diagnostic accuracy of the coronal 3D-PDW-SPIR technique for detecting ISL tears were 100, 96.9, and 97.9%, respectively, which were significantly higher than those of the sagittal STIR (p = 0.000), coronal STIR (p = 0.000), and sagittal 3D-PDW-SPIR (p = 0.001) techniques.

Conclusion

Compared to other MR methods, coronal 3D-PDW-SPIR provides a more accurate diagnosis of ISL disruption. Adding coronal 3D-PDW-SPIR to a routine MR protocol may help to identify PLC disruptions in cases with nearby contusion.

Transforaminal endoscopic discectomy to relieve sciatica and delay fusion in a 31-year-old man with pars defects and low-grade spondylolisthesis

Isthmic spondylolisthesis due to pars defects resulting from trauma or spondylolysis is not uncommon. Symptomatic patients with such pars defects are traditionally treated with a variety of fusion surgeries. The authors present a unique case in which such a patient was successfully treated with endoscopic discectomy without iatrogenic destabilization.

A 31-year-old man presented with a history of left radicular leg pain along the distribution of the sciatic nerve. He had a disc herniation at L5/S1 and bilateral pars defects with a Grade I spondylolisthesis. Dynamic radiographic studies did not show significant movement of L-5 over S-1. The patient did not desire to have a fusion. After induction of local anesthesia, the patient underwent an awake transforaminal endoscopic discectomy via the extraforaminal approach, with decompression of the L-5 and S-1 nerve roots. His preoperative pain resolved immediately, and he was discharged home the same day. His preoperative Oswestry Disability Index score was 74, and postoperatively it was noted to be 8. At 2-year follow-up he continued to be symptom free, and no radiographic progression of the listhesis was noted.

In this case preservation of stabilizing structures, including the supraspinous and interspinous ligaments and the facet capsule, may have reduced the likelihood of iatrogenic instability while at the same time achieving symptom control. This may be a reasonable option for select patient symptoms confined to lumbosacral radiculopathy.

Low Back Pain: A Biomechanical Rationale Based on "Patterns" of Disc Degeneration

STUDY DESIGN

A nonlinear finite element study of a lumbar spine with different "patterns" of multilevel intervertebral disc degeneration.

OBJECTIVE

To determine how different patterns of multilevel disc degeneration influence the biomechanical behavior of the lumbar spine.

SUMMARY OF BACKGROUND DATA

Because of the complex etiology of low back pain, it is often difficult to identify the specific factors that contribute to the symptoms of a particular patient. Disc degeneration is associated with the development of low back pain, but its presence is not always synonymous with symptoms. However, studies have suggested that "patterns" of disc degeneration may provide insight into such pain generation rather than the overall presence of degenerative changes. Specifically, individuals with contiguous multilevel disc degeneration have been shown to exhibit higher presence and severity of low back pain than patients with skipped-level disc degeneration (i.e., healthy discs located in between degenerated discs).

METHODS

In this study, the biomechanical differences between these patterns were analyzed using a nonlinear finite element model of the lumbar spine. Thirteen separate "patterns" of disc degeneration were evaluated using the model and simulated under normal physiological loading conditions in each of the primary modes of spinal motion.

RESULTS

The results showed that stresses and forces of the surrounding ligaments, facets, and pedicles at certain vertebral levels of the spine were generally lower in skipped-level disc degeneration cases than in the contiguous multilevel disc degenerations cases even when the skipped level contained more degenerated discs.

CONCLUSION

To our knowledge, this is the first study to illustrate the biomechanics of specific patterns of disc degeneration of the lumbar spine. Using a multilevel disc degeneration model, our study provides insights as to why various patterns of disc degeneration throughout the lumbar spine may affect motion and soft tissue structures as well that may have bearing in the clinical pathway of pain generation.

LEVEL OF EVIDENCE

N/A.

Spinous process osteotomy to facilitate the access to the spinal canal when decompressing the spinal canal in patients with lumbar spinal stenosis

Study Design

Retrospective study.

Purpose

The main purpose of this study was to investigate the union-rate of the spinous process after performing a spinous process osteotomy and whether union affects the clinical results after surgery.

Overview of Literature

In the present study, spinous process osteotomy was used to facilitate access to the spinal canal when performing a decompressive procedure for lumbar spinal stenosis. The aim of this study was to evaluate the union rate of the spinous process and its effect on the clinical results of the procedure.

Methods

All patients were included in the study that underwent a decompressive procedure through spinous process osteotomy be between January 1, 2007 and December 31, 2007. Operation protocols were reviewed. A computed tomography (CT) scan was performed to evaluate the union of the osteotomies of the spinous process. According to the CT-scans, patients were divided into three groups: "complete-union," "partial-union," and "non-union." Patients reported their clinical results through a self-administered questionnaire.

Results

The mean period of follow up was 21.6 months (range, 16-28 months). A total of 44% of the performed osteotomies were considered as united. Ten patients (18%) were classified as "complete-union," 30 patients (55%) as "partial-union," and 15 patients (27%) as "non-union." The "complete-union" group showed better clinical results and scored significantly better in the Oswestry Disability Index and EQ-5D. However, no statistical difference was found in the pain-scores. There were no differences between the "partial-union" group and the "no-union" group.

Conclusions

We found a radiologic union for 60 out of 135 (44%) spinous process osteotomies.

Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

BACKGROUND

The aim of this study was to analyze the inter-, intraligamentous, and side-related patterns of sensory nerve endings in ankle ligaments.

METHODS

A total of 140 ligaments from 10 cadaver feet were harvested. Lateral: calcaneofibular, anterior-, posterior talofibular; sinus tarsi: lateral- (IERL), intermediate-, medial-roots inferior extensor retinaculum, talocalcaneal oblique and canalis tarsi (CTL); medial: tibionavicular (TNL), tibiocalcaneal (TCL), superficial tibiotalar, anterior/posterior tibiotalar portions; syndesmosis: anterior tibiofibular. Following immunohistochemical staining, the innervation and vascularity was analyzed between ligaments of each anatomical complex, left/right feet, and within the 5 levels of each ligament.

RESULTS

Significantly more free nerve endings were seen in all ligaments as compared to Ruffini, Pacini, Golgi-like, and unclassifiable corpuscles (P ≤ .005). The IERL had significantly more free nerve endings and blood vessels than the CTL (P ≤ .001). No significant differences were seen in the side-related distribution, except for Ruffini endings in right TCL (P = .016) and unclassifiable corpuscles in left TNL (P = .008). The intraligamentous analysis in general revealed no significant differences in mechanoreceptor distribution.

CONCLUSIONS

The IERL at the entrance of the sinus tarsi contained more free nerve endings and blood vessels, as compared to the deeper situated CTL. Despite different biomechanical functions in the medial and lateral ligaments, the interligamentous distribution of sensory nerve endings was equal.

CLINICAL RELEVANCE

The intrinsic innervation patterns of the ankle ligaments provides an understanding of their innate healing capacities following injury as well as the proprioception properties in postoperative rehabilitation.

The interspinous spacer: a clinicoanatomical investigation using plastination

Purpose. The relatively new and less-invasive therapeutic alternative "interspinous process decompression device (IPD)" is expected to result in improved symptoms of neurogenic intermittent claudication (NIC) caused by lumbar spinal stenosis. The aim of the study was to analyze IPD position particularly regarding damage originating from surgical implantation. Methods. Anatomic assessments were performed on a fresh human cadaver. For the anatomic examination, the lumbar spine was plastinated after implantation of the IPDs. After radiographic control, serial 4 mm thick sections of the block plastinate were cut in the sagittal (L1-L3) and horizontal (L3-L5) planes. The macroanatomical positioning of the implants was then analyzed. The insertion procedure caused only little injury to osteoligamentous or muscular structures. The supraspinous ligament was completely intact, and the interspinous ligaments were not torn as was initially presupposed. No osseous changes at the spinal processes were apparent. Contact of the IPD with the spinous processes was visible, so that sufficient biomechanical limitation of the spinal extension seems likely. Conclusions. Minimally invasive IPD implantation with accurate positioning in the anterior portion of the interspinous place is possible without severe surgical trauma.

The use of a transition rod may prevent proximal junctional kyphosis in the thoracic spine after scoliosis surgery: a finite element analysis

STUDY DESIGN

Finite element analysis.

OBJECTIVE

Via finite element analysis: (1) to demonstrate the abnormal forces present at the top of a scoliosis construct, (2) to demonstrate the importance of an intact interspinous and supraspinous ligament (ISL/SSL) complex, and (3) to evaluate a transition rod (a rod that has a short taper to a smaller diameter at one end) as an implant solution to diminish these pathomechanics, regardless of the integrity of the ISL/SSL complex.

SUMMARY OF BACKGROUND DATA

The pathophysiology of increased nucleus pressure and increased angular displacement may contribute to proximal junctional kyphosis. Furthermore, high implant stress can be demonstrated at the upper end of the construct, possibly leading to the risk of implant failure.

METHODS

A finite element model was constructed to simulate a thoracic spinal fusion. The model was altered to remove the ISL/SSL complex at the level above the construct. Then, the model was altered again by extending the construct one level superior with a transition rod. The angular displacement, the maximum pressure in the nucleus, and stress within the implant were extracted from computational results under 2 conditions: load control and displacement control. The testing was performed with both titanium and stainless steel implants.

RESULTS

Pressure in the nucleus and angular displacement are all increased when the ISL/SSL complex is removed immediately above the instrumented levels, whereas the screw pullout force and maximum stress within the screw are decreased. The nucleus pressure increases by more than 50%. The angular displacement increases by 19% to 26%. This absence of the ISL/SSL complex simulates the clinical scenario that occurs when these structures are iatrogenically detached. Abnormal mechanics can be restored to normal level by extending the construct rostral one level with a transition rod. Furthermore, the elevated nucleus pressure and angular displacement noted even when the ISL/SSL complex is intact can be avoided with the use of a transition rod. Under the same bending moment (3 Nm), the nucleus pressure at the level immediately cephalad is up to 23% lower than the pressure in a standard construct. The angular displacement is 18% to 19% less than the standard construct. The maximum implant stress is also decreased by as much as 60%.

CONCLUSION

Finite element modeling suggests that the pathomechanics at the proximal end of a scoliosis construct may be diminished by preserving the ISL/SSL complex and possibly completely eliminated with the use of rods with a diameter transition at the most proximal level.

Sequential damage assessment of the different components of the posterior ligamentous complex after magnetic resonance imaging interpretation: prospective study 74 traumatic fractures

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To study whether there is a sequential pattern in the posterior ligamentous complex (PLC) rupture caused by deforming traumatic forces by analyzing magnetic resonance (MR) images in a consecutive prospective cohort of patients with traumatic vertebral fracture.

SUMMARY OF BACKGROUND DATA

PLC plays an important role in vertebral stability. However, the sequence in which the different components of the PLC tear, in the face of traumatic forces, has not been yet described.

METHODS

Prospective study of 74 consecutive vertebral acute traumatic fractures analyzed using radiography and magnetic resonance imaging (MRI) (FS-T2-w/short-tau inversion-recovery [STIR] sequences). Fracture morphology was classified according to the AO classification. Integrity of each PLC component-facet capsules, interspinous ligament (ISL), supraspinous ligament (SSL), and ligamentum flavum (LF)-was assessed and classified as intact, edema, or disruption. ISL edema was further subdivided depending on the extension (>50%/<50%). We analyzed the association between MRI signal and the AO progressive scale of morphological damage.

RESULTS

AO type A1/A2 fractures associated with only facet distraction. A3 fractures showed additional ISL edema, usually less than 50%, with neither SSL nor LF disruption. Type B1 fractures associated with facet distraction, ISL edema or disruption, and low rate of SSL/LF disruptions; B2 fractures increased SS/LF disruption rates. Type C fractures associated with facet fracture or dislocation and ISL, SSL, or LF complete rupture. We found high association (P < 0.001) between AO progressive scale and MRI signal. MRI analysis showed that posterior distraction forces begin in the facets and extend throughout the ISL, starting at its posterosuperior margin (finally disinserting the SSL superiorly) and traveling diagonally toward anteroinferior border, finally tearing the LF.

CONCLUSION

MR images correlated with AO progressive scale of morphological damage, which showed a progressive orderly rupture sequence among the different PLC components as traumatic forces increased.

What is the source of chronic low back pain and does age play a role?

OBJECTIVE

The objective of this study was to estimate the prevalence, mean age, and association of prevalence and age of lumbar internal disc disruption (IDD), facet joint pain (FJP), sacroiliac joint pain (SIJP), spinal and pelvic insufficiency fractures, interspinous ligament injury/Baastrup's Disease, and soft tissue irritation by fusion hardware.

DESIGN

The study's design was a retrospective chart review.

SETTING

The study was set in an academic spine center.

PATIENTS

A total of 378 cases from 358 patients were reviewed of which 170 cases from 156 patients who underwent diagnostic procedures were included.

INTERVENTIONS

Discography, dual diagnostic facet joint blocks, intra-articular sacroiliac joint injections, anesthetic injections of painful interspinous ligaments/opposing spinous processes/posterior fusion hardware, or percutaneous augmentation were performed.

OUTCOME MEASURES

Prevalence and age were analyzed for each diagnosis group.

METHODS

Patients with recalcitrant low back pain underwent diagnostic procedures based on their clinical presentation until the pain source was identified.

RESULTS

The prevalence of internal disc disruption, facet joint pain and sacroiliac joint pain was 42%, 31%, and 18%, respectively. Patients with internal disc disruption were significantly younger than those with facet joint pain or sacroiliac joint pain. Increased age was associated with a decreased probability of internal disc disruption and increased probabilities of facet joint pain and sacroiliac joint pain as the source of low back pain until approximately age 70.

CONCLUSION

Our data confirm the intervertebral disc as the most common etiology of chronic low back pain in adults. Based on our sample, the younger the patient, the more likely low back pain is discogenic in origin. Facetogenic or sacroiliac joint pain is more likely in older patients.

Reprodutibilidade intra e interobservadores da classificação de Fujiwara para degeneração do ligamento interespinhoso por meio de ressonância magnética e relação entre as lesões degenerativas do disco intervertebral e do ligamento interespinhoso

OBJETIVO: avaliar a aplicabilidade da classificação de Fujiwara em uma análise intra e interobservadores e compará-la com a classificação de Pfirrmann. MÉTODOS: foram avaliados 87 ligamentos interespinhosos e discos intervertebrais de 29 pacientes (16 mulheres e 13 homens), com média de idade de 49 anos (24 a 78 anos), por meio da ressonância magnética pela classificação de Fujiwara e de Pfirrmann. A avaliação de Fujiwara foi realizada por três observadores, em duas ocasiões, com intervalo mínimo de 15 dias. A avaliação de Pfirrman foi realizada pelos três observadores em um único tempo. Utilizamos o índice de Kappa para comparar a variação intra e interobservadores. RESULTADOS: a concordância intraobservadores foi considerada boa; no entanto, a concordância interobservadores foi pobre, com índices de Kappa menores que 0,2. CONCLUSÃO: a classificação de Fujiwara não se mostrou reprodutiva para avaliação do ligamento interspinhoso. No entanto, a maior divulgação e utilização dessa classificação podem torná-la um bom instrumento de comparação entre resultados de diferentes estudos.

Magnetic resonance imaging grading of interspinous ligament degeneration of the lumbar spine and its relation to aging, spinal degeneration, and segmental motion

OBJECT

Degenerative changes of the interspinous ligaments (ISLs) have generally been ignored in previous studies. Factor-related causes, the effects that these changes have on other structures within the spinal functional unit, and their relation to kinematic changes in the spine are lacking. In this study, the authors evaluated the reliability of a proposed MR imaging grading system of ISL degeneration (ISLD). They also investigated the relationship between ISLD and aging, disc/facet joint degeneration, and lumbar segmental motion.

METHODS

The authors studied 256 lumbar motion segments from L-2 to S-1 in 64 patients (35 men and 29 women) with a mean age of 46.08 years (range 23–85 years). An MR imaging–based grading system for ISLD was developed and ranged from Grade A (mild) to Grade D (severe). The reliability was tested, and the correlation of the grade with the severity of the disc and facet joint degeneration was examined. The segmental motion of each functional unit was measured using flexion/extension MR imaging, and their relationships with ISL grades were identified.

RESULTS

Grade A was observed in 115 levels (44.9%), Grade B in 105 (41.0%), Grade C in 15 (5.9%), and Grade D in 21 levels (8.2%). The kappa coefficients for intraobserver and interobserver agreements were substantial to excellent (intraobserver [0.871] and interobserver [0.721–0.807]). Grade D was observed primarily in elderly patients. Segmental motion tended to decrease in the most severe grade, with a significant difference in angular mobility. As the severity of ISLD increased, the severity of disc/facet joint degeneration increased (p < 0.001 and p < 0.05, respectively).

CONCLUSIONS

The authors proposed a reliable and reproducible grading system that may be used to investigate spinal kinematics in association with ISLD. The authors' findings illustrated the distribution of ISLD grades. The most severe grade occurred primarily in elderly patients. Mobility decreased in the most severe grade; therefore, the stage of ISLD should be taken into consideration when evaluating spinal stability.

MRI classification of interspinous ligament degeneration of the lumbar spine: intraobserver and interobserver reliability and the frequency of disagreement

Posterior spinal ligament pathology is becoming increasingly recognized as a significant cause of low back pain. Despite the growing clinical importance of interspinous ligament degeneration in low back pain patients, formal reliability studies for the magnetic resonance imaging (MRI) evaluation of interspinous ligaments have not been performed. We proposed an MRI classification system for interspinous ligament degeneration and conducted a comprehensive reliability and reproducibility assessment. Fifty patients who had low back pain with or without leg discomfort (26 males and 24 females) with a mean age of 48.8 years (range 23-85 years) were studied. The classification for lumbar interspinous ligament degeneration was developed on the basis of the literature using mid-sagittal T1- and T2-weighted images. Three spine surgeons independently graded a total of 200 interspinous ligament levels. Intraobserver and interobserver reliability were assessed by kappa statistics. The frequency of disagreement was also identified. The intraobserver agreement was excellent in all readers (kappa range 0.840-0.901). The interobserver agreement was lower as expected, and was substantial to excellent (kappa range 0.726-0.818). Overall complete agreement was obtained in 87.8% of all interspinous ligament levels. A difference of 1, 2, and 3 grades occurred in 8.1, 3.0, and 1.1% of readings, respectively. This proposed MRI classification of interspinous ligament degeneration was simple, reliable, and reproducible. Its use as a standardized nomenclature in clinical and radiographic research may be recommended.