Nerve root compression in spondylolysis and spondylolisthesis

Long-term CT follow-up of patients with lumbar spondylolysis reveals low rate of spontaneous bone fusion

OBJECTIVES

Knowledge about the long-term outcome of patients with lumbar spondylolysis (LS) is limited. This study assessed the frequency of bone fusion in conservatively treated lumbar spondylolysis with photon counting detector computed tomography.

METHODS

Patients with lumbar spondylolysis diagnosed with CT or MRI were prospectively enrolled and underwent CT 5-10 years after initial imaging. Image assessment included evaluation of Meyerding grade, listhesis size, measurement of the lysis gap, and disc integrity on the lysis level. Comparisons were made between bone fusion as the primary endpoint and sex, body mass index, age at diagnosis, follow-up interval, size of listhesis, Meyerding grade, size of the lysis gap, sports activity, and presence of pain.

RESULTS

A total of 39 patients (26.0 ± 3.1 years, 15 female) with lumbar spondylolysis on 41 levels were included after a mean follow-up period of 9.1 ± 2.2 years. Nine patients (22.0%, four female) showed complete fusion of the lysis gap. Patients with bone fusion of the lysis gap had a significantly lower Meyerding grade (p = 0.01), smaller size of the listhesis (p = 0.019), and smaller anterior and posterior lysis gap size (p = 0.046 and p = 0.011, respectively). Unilateral lyses showed significantly higher fusion rates than bilateral lyses (40.0% vs. 16.1%, p = 0.01). No statistically significant difference was found for pain at follow-up between patients with and without bone fusion (p = 0.253).

CONCLUSION

Bone fusion occurred in about a fifth of conservatively treated lumbar spondylolysis after a follow-up period of 9 years. Factors associated with a successful fusion were a lower Meyerding grade, minimal listhesis, and a small lysis gap.

Impact of lumbar spine pathology on asymmetrical hallux valgus in a population-based cohort study

This study aims to investigate the influence of lumbar spine disorders on the development of asymmetric hallux valgus (HV). Data from the fifth survey of the Osteoarthritis/Osteoporosis Against Disability (ROAD) study, a nationwide prospective study in Japan, were analyzed. HV severity was categorized into 4 grades based on the radiographic HV angle, and asymmetric HV was defined as having at least one HV on either side, with a difference of two or more severity grades between the left and right. Controls were matched from both the Normal group (without HV on both sides) and the Symmetric group (HV on at least one side with a difference of one or less severity grades). Univariate analysis assessed lumbar conditions, and multinomial logistic regression analysis explored the association between lumbar spine disorders and asymmetric HV. Among 1997 participants, 27 had asymmetric HV. Univariate analysis revealed a higher incidence of L5 spondylolisthesis and scoliosis in the Asymmetric group. Multinomial logistic regression analysis revealed that scoliosis independently increased the likelihood of asymmetrical HV (Odds ratio [OR] = 3.586, 95%Confidence interval [CI] 1.111-11.582), but showed no significant impact on symmetrical HV (OR 0.910, 95% CI 0.355-2.334). Asymmetric HV is rare but may be associated with lumbar spine disorders, particularly scoliosis.

Enhancing endoscopic foraminal decompression in adult isthmic spondylolisthesis: the potential influence of lateral recess isthmic spur and our case series of an innovative craniocaudal interlaminar approach via unilateral biportal endoscopic spinal surgery

BACKGROUND

The NASS guideline cannot recommend any of the surgical treatment options toward adult isthmic spondylolisthesis (AIS) since 2014. After the introduction of endoscopic decompression, instead of treating the spondylolysis itself, treatment can specifically target the refractory radicular pain developed during the degeneration progress without devastating the peripheral soft tissue. However, we noticed that endoscopic transforaminal decompression seems to be less effective in AIS compared to other types of degenerative spondylolisthesis. Thus, we came up with a novel craniocaudal interlaminar approach, utilizing the proximal adjacent interlaminar space to perform bilateral decompression and observed the pathoanatomy of pars defect directly and tried to identify the cause of decompression failure.

METHODS

From January 2022 to June 2022, 13 patients with AIS underwent endoscopic decompression via the endoscopic craniocaudal interlaminar approach and were followed up for at least 6 months. Visual Analogue Scale, Oswestry Disability Index and MacNab scores were recorded to monitor patients' clinical recovery. All endoscopic procedures were recorded and reviewed to illustrate the pathoanatomy.

RESULTS

Four patients required minor revision via the same technique. One of them required it due to incomplete isthmic spur resection, two due to neglected disc protrusion, and the other due to root subpedicular kinking in higher grade anterolisthesis. All patients' clinical condition improved significantly subsequently. After reviewing the endoscopic video, we have observed that the hook-like, ragged spur originating from the isthmic defect extends beyond the region around the foramen. Instead, it extends proximally into the adjacent lateral recess, resulting in impingement along the fracture edge above the index foramen and, in some cases, even in the extraforaminal area.

CONCLUSIONS

The broad spanning isthmic spur extending to the proximal adjacent lateral recess might be the reason why the transforaminal approach yielded less satisfactory results due to the incomplete decompression result from approach related restriction. Our study demonstrated an optimistic outcome by applying decompression from the upper level. Therefore, we propose that the craniocaudal interlaminar approach might be a better route for decompression in adult isthmic spondylolisthesis.

Vacuum curette lumbar discectomy mechanics for use in spine surgical training simulators

Simulation in surgical training is a growing field and this study aims to understand the force and torque experienced during lumbar spine surgery to design simulator haptic feedback. It was hypothesized that force and torque would differ among lumbar spine levels and the amount of tissue removed by ≥ 7%, which would be detectable to a user. Force and torque profiles were measured during vacuum curette insertion and torsion, respectively, in multiple spinal levels on two cadavers. Multiple tests per level were performed. Linear and torsional resistances of 2.1 ± 1.6 N/mm and 5.6 ± 4.3 N mm/°, respectively, were quantified. Statistically significant differences were found in linear and torsional resistances between all passes through disc tissue (both p = 0.001). Tool depth (p < 0.001) and lumbar level (p < 0.001) impacted torsional resistance while tool speed affected linear resistance (p = 0.022). Average differences in these statistically significant comparisons were ≥ 7% and therefore detectable to a surgeon. The aforementioned factors should be considered when developing haptic force and torque feedback, as they will add to the simulated lumbar discectomy realism. These data can additionally be used inform next generation tool design. Advances in training and tools may help improve future surgeon training.

Changes in L4/5 Intervertebral Foramen Bony Morphology with Age

The purpose of this study was to explore the morphological changes in L4/5 intervertebral foramen with age using a digital method. The closed boundaries of the intervertebral foramen (IGES) in different sagittal slices (inside, middle and outside) were obtained from Mimics, and then imported to a custom-written program, which provided quantitative distance between the nerve root and the closed curves. The quantitative information of each age group was used to produce radar chart and line chart for morphological and statistical analyses. Overall, the intervertebral foramen changes mainly occurred in the inner part from middle age to old age. The foraminal height decreased with age in the inside sagittal slice, while no significant difference was found in the middle sagittal slice or the outside sagittal slice. The foraminal width showed no decrease in each age group or each sagittal plane. The present study described foraminal geometry of asymptomatic males in different sagittal slices with age. This information enhances the knowledge of anatomical changes in intervertebral foramen with age, which provides better understanding of the pathology of intervertebral foramen diseases.

Results of Buck Screw Fusion in Grade I Spondylolisthesis

The results of posterolateral screw fixation using the Buck technique performed on 24 patients with painful isthmic spondylolysis and up to grade I spondylolisthesis in the lumbar spine are reported. The average age at operation was 29 years and average follow-up was 5 years with a range of 13 months to 12 years. Operations were performed for persistent disabling low back pain. At review 21 patients were either free of pain or complained of only occasional backache and discomfort. All but two patients were satisfied with the operation and rated the result as excellent or good. It is concluded that Buck screw fixation is a safe and reliable method of treatment for painful Grade I spondylolisthesis due to isthmic spondylolysis in the young active adult with a low complication rate.

Anatomic variability of 120 L5 spondylolytic defects

Study Design Adult human osteologic specimens were assessed for spondylolytic defects and characterized. Objectives To characterize and determine the prevalence of spondylolytic defects in an osteological collection. Methods Lumbar vertebrae from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History were examined. Digital images of specimens with L5 isthmic spondylolytic defects were analyzed, examining the distance of the pars defect in the sagittal plane in relation to the caudal aspect of the pedicle. Results There were 95 bilateral complete (BC), 16 unilateral incomplete (UI), 5 unilateral complete (UC), and 4 unilateral complete defects with an incomplete defect on the contralateral side. The mean distance of BC defects from the pedicle and inferior vertebral end plate was 4.03 mm and 4.88 mm, respectively. The mean distance of the defect from the inferior end plate on the left and right sides were 5.31 mm and 4.44 mm, respectively (p = 0.001, correlation coefficient = 0.56). The mean distance of UI and UC defects from the inferior end plate was 6.38 mm and 2.6 mm, respectively. Conclusion L5 spondylolytic defects were found in 3.87% of the sample. This large-scale description of isthmic spondylolytic defects reveals that significant variability exists in the location of the defect. The anatomic location of the pars defect likely plays a role in the development of L5 nerve root compression and radiculopathy in this clinical scenario. Classifying these defects might allow surgeons to better identify those patients who might benefit from fusion alone without posterior decompression.

Conservative treatment for pediatric lumbar spondylolysis to achieve bone healing using a hard brace: what type and how long?: Clinical article

OBJECT

Various kinds of trunk braces have been used to achieve bone healing in cases of pediatric lumbar spondylolysis. However, the optimal brace for achieving bone healing is unclear. The purpose of the present study was to determine in what types of spondylolysis bone healing can be achieved and how long it takes.

METHODS

In this prospective study, 63 pars interarticularis defects (spondylolysis) among 37 patients who were younger than 18 years (mean 13.5 ± 2.7 years) were treated using a hard brace. The youngest patient was 8 years old. Based on the results of CT scanning, the lyses were classified into 3 categories: early, progressive, and terminal defects. Progressive defects were further divided into 2 types according to STIR MRI findings: those with high signal intensity at the adjacent pedicle and those with low signal intensity (that is, a normal appearance). A hard brace, such as a molded plastic thoracolumbosacral orthosis, was used to immobilize the trunk. Approximately every 3 months, CT scanning was performed to evaluate bone healing until approximately 6 months.

RESULTS

The union rates were 94%, 64%, 27%, and 0% for the early, progressive with high signal intensity, progressive with low signal intensity, and terminal defects, respectively. It was noted that no terminal defect was healed using conservative treatment. The mean time to healing among the defects that showed bone healing was 3.2, 5.4, and 5.7 months for the early, progressive with high signal intensity, and progressive with low signal intensity groups, respectively.

CONCLUSIONS

Patients with early-stage defects are the best candidates for conservative treatment with a hard brace because more than 90% of such cases can be healed in 3 months.

Intervertebral foramen size and volume changes in low grade, low dysplasia isthmic spondylolisthesis

STUDY DESIGN

Anatomic study.

OBJECTIVE

The purpose of this study is to determine the effect of the slip amount, slip angle, and disc height on the geometry of the L5 foramen in low-grade, low-dysplasia isthmic L5 spondylolisthesis using a human cadaveric model.

SUMMARY OF BACKGROUND DATA

Radicular pain and varying degrees of nerve root dysfunction are present in many adult isthmic spondylolisthesis patients and can be the result of compression of the L5 root within its foramen.

METHODS

The intervertebral foramens of six L5 vertebra and sacrum cadaver specimens had a standardized pars defect created and were mounted on an adjustable frame. Plasticene molds of the foramens were made by varying sagittal translocation (0%, 12.5%, 25%, and 50%), slip angle (kyphotic 10° and lordotic 0°, 10°, 20°, and 30°), and disc height (0, 5, and 10 mm). The volume of each mold was measured. The surface area was determined by sagittally slicing on a microtome the mold and each section's face was measured by computer image analysis.

RESULTS

The area and volume of the foramen at a sagittal slip of 0%, slip angle of 0°, and 0 mm disc height were used as a control. As disc height decreased from 10 to 5 mm, 10 to 0 mm, and 5 to 0 mm, the foramen area and volume significantly decreased (P < 0.05). Incremental slip percentage from 0% to 12.5%, 25%, and 50% produced significantly reduced foramen area and volumes (P < 0.05). As slip angle increased from 10° kyphosis to 0°, 10°, 20°, and 30° lordosis, foramen area and volume decreased (P < 0.05).

CONCLUSION

Disc height and slip percentage had the largest effect on intervertebral foramen area and volume in this model of low-grade, low-dysplasia isthmic spondylolisthesis. Slip angle changes affected foramen area to a lesser degree. Surgical treatment strategies should consider restoration of disc height in cases with foraminal stenosis.

Causes of radiculopathy in young athletes with spondylolysis

BACKGROUND

The main clinical symptom of lumbar spondylolysis is lower back pain. Radiculopathy rarely occurs without vertebral slippage. Hypothesis Spondylolysis in young athletes can cause lumbar radiculopathy.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Ten patients (7 males and 3 females) were included in this study. The age of the patients ranged from 12 to 27 years. We employed plain radiography, computed tomography, magnetic resonance imaging, and selective radiculography if needed.

RESULTS

The pathomechanism was classified into nonspondylolytic radiculopathy (3 cases) and spondylolytic radiculopathy (7 cases). In the nonspondylolytic group, 1 patient had a juxta-facet cyst at L4-5 and 2 patients had a herniated nucleus pulposus. In the other group, spondylolytic-related factors caused radiculopathy, and spondylolysis was in the early or progressive stage in all 7 patients. Radiologic findings indicated that radiculopathy was caused by extraosseous hematoma or edema in the vicinity of the fracture site. The radiculopathy disappeared within a month of nonoperative management, and radiologic abnormalities disappeared 3 to 6 months later.

CONCLUSION

Radiculopathy can occur together with lumbar spondylolysis without slippage in young athletes. We propose extra-osseous hematoma or edema at the site of spondylolysis as the unique pathomechanism causing radiculopathy in young athletes. Radiculopathy is rare in athletes with spondylolysis. Magnetic resonance imaging is a useful tool to clarify the pathologic changes that induce the radiculopathy for both spondylolytic and nonspondylolytic factors.

Adult isthmic spondylolisthesis

Isthmic spondylolisthesis is present in a small subset of the adult population. Although the incidence of low back pain in these persons is similar to that of the general population, both pars interarticularis defect and forward slip can serve as unique pain generators. Neurologic symptoms may result from nerve root impingement related to the pars defect or degenerative changes associated with the deformity. Most symptomatic cases are successfully managed nonsurgically, but patients with intractable pain or neurologic symptoms may benefit from surgical decompression and stabilization. Surgical intervention has shown >80% success in appropriately selected patients, with a low incidence of complications. Surgical techniques include decompression, posterolateral fusion, anterior lumbosacral interbody fusion, and circumferential fusion methods. Circumferential fusion results in improved fusion rates and, in some studies, superior clinical outcomes. The choice of procedure is generally guided by the patient's radiographic and clinical findings as well as risk-benefit considerations.

Nerve root decompression without fusion in spondylolytic spondylolisthesis: long-term results of Gill's procedure

Nerve root decompression with instrumented fusion is currently most commonly performed in the treatment of patients with spondylolytic spondylolisthesis. The relationship between successful fusion and clinical outcome remains controversial, thereby questioning the necessity of fusion. Nerve root decompression without fusion, i.e. Gill's procedure, might be a less invasive surgical alternative with comparable clinical outcome. The objective of this study is to compare the long-term results of Gills's procedure with data from literature on decompression with fusion, and, moreover, to determine if a future randomised trial is legitimate. We retrospectively reviewed the long-term results of Gill's procedure in patients with grade I or II spondylolytic spondylolisthesis. All patients suffered from leg pain with or without low back pain. No patient had low back pain alone. In 17 patients a bilateral and in 25 patients a unilateral Gill's procedures were performed. The patients were evaluated at three follow-up moments. On moment 1, 38 patients were clinically examined on their last out-patient control (mean follow-up 11 months). On moment 2, 34 patients were interviewed by telephone (mean follow-up 4.4 years). The final long-term follow-up moment 3 (mean follow-up 10.5 years) included a mailed patient-satisfaction questionnaire of 31 patients (response rate 74%). No surgical complication occurred. Ten of the 42 patients were reoperated because of persistent or recurrent radicular pain (mean time interval 2.9 years). Kaplan-Meier analysis showed a disease-free survival rate of 79% at 5 years and 72% at 10 years after the index operation. On the three follow-up moments, the improvement of leg pain was 92, 97 and 88%, respectively. The final long-term follow-up showed 71% good result in terms of patient satisfaction. The Gill's procedure is a less invasive surgical technique in the treatment of patients with leg pain due to low-grade spondylolytic spondylolisthesis. This technique can be considered as an alternative to instrumented fusion in selected cases. Preoperative instability, discectomy at the affected level and neuroforaminal nerve root compression seem to be negative influencing factors, increasing the risk for secondary instrumented surgery. The results of this study justify a randomised trial.

A new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Technical note

The authors describe a new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Short-term clinical outcome was evaluated. Surgery-related indications were: 1) radiculopathy without low-back pain; 2) no spinal instability demonstrated on dynamic radiographs; and 3) age older than 40 years. Seven patients, four men and three women, fulfilled these criteria and underwent endoscopic decompressive surgery. Their mean age was 60.9 years (range 42-70 years). No subluxation was present in four patients, whereas Meyerding Grade I slippage was demonstrated in three. For endoscopic decompression, a skin incision of 16 to 18 mm in length was made, and fenestration was performed to identify the affected nerve root. The proximal stump of the ragged edge of the spondylotic lesion, and the fibrocartilaginous mass compressing the nerve root were removed. The follow-up period ranged from 6 to 22 months (mean 11.7 months). Clinical outcome was evaluated using Gill criteria; in three patients the outcome was excellent, and in four it was good. This new endoscopic technique was useful in the decompression of nerve roots affected by spondylolysis, the technique was minimally invasive, and the clinical results were acceptable.

Anatomic issues related to cervical and lumbosacral radiculopathy

The anatomy of cervical and lumbar spinal nerves is well established. Knowledge of the normal and pathoanatomy of impingement of these roots is helpful in the diagnosis of radiculopathy in many cases. Frequently, symptoms and signs do not correlate with expected anatomical patterns. Variations of nerve roots, spinal nerves, and plexuses occur commonly. Neuroanatomical anomalies and musculoskeletal abnormalities account for many of the variations seen with unexpected radicular patterns. Unfortunately, the delineation of segmental innervation has been achieved by several different methods and definitive studies are lacking. Although there is a regular and orderly progression of innervation within each individual, it is likely that innervation patterns differ considerably between individuals.

A study of mechanoreceptors in fibrocartilage masses in the defect of pars interarticularis

We investigated the origin of low back pain associated with lumbar spondylolysis and spondylolytic spondylolisthesis by removing fibrocartilage masses from the lytic sites in symptomatic patients and staining the masses by the Gairns gold chloride method to examine mechanoreceptors. The fibrocartilage masses were found to contain four types of mechanoreceptors: Pacinian corpuscles, Ruffini receptors, Golgi tendon organ-like receptors, and free nerve endings. All of these mechanoreceptors were present at the periphery of the specimens, and Ruffini receptors and free nerve endings were abundant. Some mechanoreceptors had a slightly atypical structure, in addition to those with typical morphology. Comparison with mechanoreceptors in normal lumbar facet joint capsules showed that there were more mechanoreceptors in the fibrocartilage masses and a greater proportion of atypical structures at lytic sites. The presence of mechanoreceptors at lytic sites suggests that the fibrocartilage masses are not simply scar tissue filling the defect. Rather, these masses also appear to play a protective role by sensing instability via mechanoreceptors and transmitting this information as pain, while at the same time acting as ligament-like tissue that connects and stabilizes the separated vertebral arches.

Microdecompression without fusion for radiculopathy associated with lytic spondylolisthesis

Patients with symptomatic L-5 nerve root compression and associated lytic spondylolisthesis are commonly treated by bilateral wide posterior decompression and concomitant fusion, often accompanied by transpedicular instrumentation. More limited surgery aimed solely at the relief of nerve root compression offers the potential for significant relief of radicular pain while avoiding iatrogenic instability, thereby alleviating the need for arthrodesis with its increased surgical morbidity. Nine patients with unilateral radicular symptoms referable to the L-5 nerve root, minimal back pain, and a lytic pars lesion with mild spondylolisthesis underwent unilateral microdecompression on their symptomatic side without associated fusion. All patients obtained relief of radicular pain at both short- and long-term follow-up examination. One patient demonstrated increased back pain and, accordingly, the procedure is now recommended only for patients with no greater than a 25% spondylolisthesis. Unilateral microdecompression without stabilization is an effective and safe method for relieving radicular pain in patients with a lytic pars defect, a mild spondylolisthesis, and minimal back pain. This therapeutic option should be considered in select cases as an alternative to bilateral wide decompression with fusion and instrumentation.