Circumferential fusion for degenerative lumbar spondylolisthesis complicated by distal junctional grade 4 spondylolisthesis in the sub-acute post-operative setting.

INTRODUCTION: Surgical management for lumbar stenosis is generally safe and provides significant improvements in pain, disability, and function. Successful lumbar decompression hinges on removing an appropriate amount of lamina and other compressive pathology in the lateral recess. Too little bony decompression can result in persistent pain and disability, while over resection of the pars and/or facets may jeopardize spinal stability. CASE REPORT: In this unique report, we present for the first time an acute iatrogenic grade 4 L5-S1 spondylolisthesis distal to a L3-5 laminectomy and circumferential instrumented fusion due to bilateral iatrogenic L5 pars fractures and its management and clinical outcomes after revision operation. The patient presented with worsening pain, neurologic compromise, and severe sagittal imbalance. The iatrogenic, high-grade spondylolisthesis was urgently addressed with a L5-S1 anterior lumbar interbody fusion and extension of posterior instrumentation to the pelvis, which resulted in considerable pain relief, resolution of neurologic deficits, and reconstitution of acceptable sagittal imbalance. CONCLUSION: All attempts during a lumbar decompression should be made to prevent iatrogenic pars fractures, as they may result in severe sagittal imbalance, neurologic compromise, and persistent disability. Iatrogenic, high-grade L5-S1 spondylolisthesis can be successfully treated with reduction using circumferential fusion of the lumbosacral junction.

Endoscopic-assisted fusion for lumbar pars fracture repair in an adolescent patient.

Minimally invasive repair of pars defects can be achieved via means of cannulation followed by tubular decortication. Given these injuries typically occur in pediatric and adolescent patients, minimal disruption to surrounding tissue during the repair is ideal. The use of an endoscopic approach to assist with repair and fusion across the pars defect is a novel consideration in the pediatric demographic, and in this case report we highlight our experience and rationale for this in treating a 14-year-old male athlete with lumbar 5 pars fracture. Radiographic evidence of bony fusion was seen by the third postoperative month. In this case report we demonstrate the invasive nature of this repair can be minimized further than current convention with successful radiographic and clinical outcomes.

Traumatic L5/S1 bilateral locked facets with bilateral pars fractures - A case report.

Background: Although rare, traumatic lumbosacral (L/S) Grade I spondylolisthesis (i.e., Lumbar locked facet syndrome) is characterized by unilateral or bilateral facet dislocations. Case Description: A 25-year-old male presented following a high velocity road traffic accident with back pain and tenderness at the L/S junction. His radiologic images showed bilateral locked facets at the L5/S1 level with Grade 1 spondylolisthesis, bilateral pars fractures, acute traumatic L5/S1 disc herniation, and disruption of the anterior and posterior longitudinal ligaments. After undergoing a L4-S1 laminectomy with pedicle screw fixation, he became asymptomatic and remained neurologically stable. Conclusion: L5/S1 facet dislocation whether unilateral or bilateral needs to be diagnosed early and treated with realignment and instrumented stabilization.

Does Direct Surgical Repair Benefit Pars Interarticularis Fracture? A Systematic Review and Meta-analysis.

BACKGROUND: Promising results have been shown in previous studies from direct pars interarticularis repair. These include Scott wiring, Buck repair, pedicle screw repair, and Morscher techniques. In addition, several minimally invasive techniques have been reported to show high union rates, low rates of implant failure and wound complications, shorter length of stay, a lower postoperative pain score with faster recovery, and minimal blood loss. OBJECTIVES: To compare the evidence on techniques for direct pars interarticularis repair. STUDY DESIGN: Systematic review and meta-analysis. SETTING: Review article. METHODS: We conducted a comprehensive search of databases to identify studies assessing outcomes of direct pars interarticularis defect repair. Two authors independently screened electronic search results, performed study selection, and extracted data for meta-analysis. Sensitivity and subgroup analyses were performed to assess risk of bias. RESULTS: Forty studies were included in the final analysis. Union rate was higher in the pedicle screw repair group (effect size [ES] 95%; 95% CI, 86% to 100%), followed by the Buck repair group (ES 93%; 95% CI, 86% to 98%), Scott wiring (ES 85%; 95% CI, 63% to 99%), and Morscher method group (ES 63%; 95% CI, 2% to 100%). Positive functional outcome was higher for the Morscher method (ES 91%; 95% CI, 86% to 96%), followed by the Buck repair group (ES 85%; 95% CI, 68% to 97%), pedicle screw repair (ES 84%; 95% CI, 59% to 99%) and Scott repair group (ES 80%; 95% CI, 60% to 95%). Complication rates were highest among the Scott repair group (ES 12%; 95% CI, 4% to 22%) and Morscher method group (ES 12%; 95% CI, 0% to 34%). LIMITATIONS: Heterogeneity of the included studies were noted. However, we performed sensitivity analyses from the available data to address this issue. CONCLUSION: Our results indicate that pedicle screw repair and Buck repair may be associated with a higher union rate and lower complication rates compared to the Scott repair and Morscher method. Ultimately, the choice of technique should be based on the surgeon's preference and experience.

The Aging Population Faces Increased Risk for Musculoskeletal Pathologies: The Problematic Atlas-Axis Instability.

Spinal cord injury (SCI), particularly of the traumatic variety, is a relatively common condition that disproportionately affects the elderly. Cases of SCI with nontraumatic etiologies in the geriatric population have increased over the last 20 years, however. Pannus formation, resulting from chronic inflammation of the spine, is one such etiology that may progress to SCI and potentially result in rapid neurological degeneration. Here we describe a case of an elderly woman who presented with a sudden onset of quadriplegia without a history of trauma. Radiography revealed upper cervical instability and fracture due to the presence of a large erosive pannus formation. Unfortunately, in the context of severe SCI, the reversibility of neurological decline is not always guaranteed. Additionally, surgical intervention is not always appropriate, especially among the elderly population, where medical management and end-of-life care are more often delivered.

Curious Case of Atypical Hangman's Fracture: C2-C3 Listhesis without Pars Fracture.

Traumatic spondylolisthesis of axis or hangman's fracture is the second most common C2 vertebra injury. We present a report of a young man presenting with a history of fall from height with C2 to C3 spondylolisthesis without any evidence of injury to pars interarticularis but with associated injury to capsular ligament of facet joint along with posterior spinous ligamentous injury. The patient underwent intraoperative reduction in listhesis with posterior screw fixation. The patient showed uneventful postoperative course with neurological improvement at 6-week follow-up. Hangman's fracture refers to a diverse group of injury in which the soft tissue injury has an equally important part to play as the bone fracture.

Epidemiology, Treatment, and Performance-Based Outcomes in American Professional Baseball Players With Symptomatic Spondylolysis and Isthmic Spondylolisthesis.

BACKGROUND: Repetitive lumbar hyperextension and rotation during athletic activity affect the structural integrity of the lumbar spine. While many sports have been associated with an increased risk of developing a pars defect, few previous studies have systematically investigated spondylolysis and spondylolisthesis in professional baseball players. PURPOSE: To characterize the epidemiology and treatment of symptomatic lumbar spondylolysis and isthmic spondylolisthesis in American professional baseball players. We also sought to report the return-to-play (RTP) and performance-based outcomes associated with the diagnosis of a pars defect in this elite athlete population. STUDY DESIGN: Descriptive epidemiology study. METHODS: A retrospective cohort study was conducted among all Major and Minor League Baseball (MLB and MiLB, respectively) players who had low back pain and underwent lumbar spine imaging between 2011 and 2016. Players with radiological evidence of a pars defect (with or without listhesis) were included. Analyses were conducted to assess the association between player-specific characteristics and RTP time. Baseball performance metrics were also compared before and after the injury episode to determine whether there was an association between the diagnosis of a pars defect and diminished player performance. RESULTS: During the study period of 6 MLB seasons, 272 professional baseball players had low back pain and underwent lumbar spine imaging. Overall, 75 of these athletes (27.6%) received a diagnosis of pars defect. All affected athletes except one (98.7%) successfully returned to professional baseball, with a median RTP time of 51 days. Players with spondylolisthesis returned to play faster than those with spondylolysis, MLB athletes returned faster than MiLB athletes, and position players returned faster than pitchers. Athletes with a diagnosed pars defect did not show a significant decline in performance after returning to competition after their injury episode. CONCLUSION: Lumbar pars defects were a common cause of low back pain in American professional baseball players. The vast majority of affected athletes were able to return to competition without demonstrating a significant decline in baseball performance.

Alleviation of Chronic Low Back Pain due to Bilateral Traumatic L4 Pars Interarticularis Fractures Relieved With Steroid Injections.

Chronic back pain affects 20% of the adult population in the United States and is a significant source of disability and healthcare expenditure. One of the most common causes of chronic back pain is spondylosis. These changes result from age-related degeneration of the lumbar spine. As a result of this degeneration, spondylolisthesis can develop. Spondylolysis is a fracture of the pars interarticularis. It affects younger patients and is more prevalent in adolescents and elite athletes. It can be a debilitating condition that may force athletes into retirement as well as impair them with chronic pain and disability. Traditional treatment options include conservative management such as medications, rest, physical therapy, and rehabilitation. Surgery is reserved for patients who do not respond to conservative measures. Here we present the case of a 39-year-old mixed martial arts fighter with bilateral L4 pars interarticularis fractures and chronic low back pain. After failing conservative treatment options, this patient finally obtained significant relief with steroid injections at the level of the defect. The patient continues to do well with occasional injections and is able to maintain his mixed martial arts career. This case report provides evidence that injection therapy is a feasible alternative to surgery in patients who fail conservative therapy.

High Sacral Endplate Inclination Vector Forces Are Associated with Pars Fracture-Mediated Lumbosacral Spondylolisthesis.

OBJECTIVE: Lumbar spondylolisthesis can be related to facet arthropathy and disc degeneration or to a fracture of the pars interarticularis, but the mechanistic underpinnings of spondylolisthesis remain unclear. We posit that high sacral slope and body weight increase sacral inclination vector forces, which leads to pars fractures and exacerbates risk for spondylolisthesis. METHODS: To investigate this hypothesis, we measured the sacral slope, body weight, and S1 endplate vector forces for patients who underwent L5-S1 fusion for grade I spondylolisthesis. Patients were stratified based on presence of pars fractures versus facet arthropathy, and statistical analyses were performed to determine whether high sacral endplate inclination vector force is associated with pars fracture-mediated spondylolisthesis. RESULTS: We identified 131 patients who had L5-S1 fusion for spondylolisthesis. The mean age was 56 years, and 57% were female. The body weight of patients ranged from 45.4 to 141.9 kg with an average of 83.8 kg; 32 patients had single-level L5-S1 spondylolisthesis secondary to bilateral L5 pars interarticularis fractures, whereas 99 patients had L5-S1 spondylolisthesis due to facet arthropathy. Patients with pars fractures had steeper sacral slopes (43.2 ± 10.1°) compared with those without pars fractures (36.8 ± 8.1°) (P = 0.0007, odds ratio 2.71). Despite having no significant differences in weight (82.7 ± 17.2 vs. 87.3 ± 17.2 kg, P = 0.189), patients with pars fractures had 49% greater sacral inclination vector forces compared with those without pars fractures (586 ± 158 N vs. 394 ± 90 N, P < 0.0001). CONCLUSIONS: These data suggest that high sacral endplate inclination vector force is a risk factor for developing pars fracture-mediated spondylolisthesis.

Utility of STIR-MRI in Detecting the Pain Generator in Asymmetric Bilateral Pars Fracture: A Report of 5 Cases.

Lumbar spondylolysis usually occurs as a stress fracture in the pars interarticularis of the vertebra. It is a prevalent sports-related disorder and a common cause of low back pain. We encountered five athletes (4 males, 1 female) with severe low back pain. Mean age was 14.5 years. All five patients were found to have bilateral pars fracture. In all cases, staging based on the findings from computed tomography scan of the right and left pars fracture was different. On short tau inversion recovery magnetic resonance imaging (STIR-MRI) of the comparatively newer more recently injured side, high signal intensity changes were obvious and dominant at the intra- and extraosseous area, which would indicate tissue edema and/or bleeding. Furthermore, the imaging findings corresponded to the side of the low back pain. In conclusion, STIR-MRI can effectively distinguish between painful pars fracture and painless pars fracture.

Pedicle screws with modular head vs. preassembled head used in cortical bone trajectory: Can pars and pedicle fractures be prevented in osteoporotic bone?

Pars and pedicle fractures as a result of CBT (cortical bone trajectory) during pedicle screw placement have been reported. The primary aim of the study is to compare the fracture rate between screws with modular heads to screws with standard pre-assembled tulip heads. The secondary aim of the study is to determine the potential variables that can be identified prior to instrumentation in order to predict risk of fractures. Twenty-four fresh frozen lumbar vertebrae were obtained from five different cadavers. Anatomical landmark measurements were obtained. Right and left pedicles of each vertebra were randomly instrumented with the preassembled head screws (n=24) and modular head screws (n=24) under video recording. X-ray images were obtained for measuring relative angle deviations between tapped and final screw trajectories. Finally, pullout tests were performed. Seventeen out of twenty-four (70.8%) of the spinous processes had to be excised in order to obtain proper trajectories. Six fractures occurred with pre-assembled head screws versus one in the modular head screws (p=0.04). Distances from the midline to the medial wall of the pedicle were marginally significant as a predictor for fracture (p=0.08). The pullout loads between both types of screws were not statistically different (p=0.38). Age was better correlated with pullout load than absolute bone density value (p<0.001). In conclusion, modular head screws had a significantly lower fracture rate than pre-assembled head screws for cortical bone trajectory in osteoporotic bone. There was no clear anatomic variable that could be measured pre-operatively to predict potential fracture risk in CBT.

Pars and pedicle fracture and screw loosening associated with cortical bone trajectory: a case series and proposed mechanism through a cadaveric study.

BACKGROUND CONTEXT: Cortical bone trajectory (CBT) technique for pedicle screw placement in the lumbar spine has become more popular since its introduction in 2009. The distinct advantages of using the CBT technique involve increased screw purchase within the cortical bone and reduced surgical dissection. However, contrary to several favorable biomechanical results, there were anecdotal reports of clinical complications associated with CBT. PURPOSE: This study aimed (1) to report on two unique pars and pedicle fracture cases involving the use of the CBT technique and (2) to perform a cadaveric pilot study to determine the possible mechanism for this fracture pattern. STUDY DESIGN/SETTING: A case report and cadaveric study were carried out. METHODS: After presenting two clinical cases, 19 fresh-frozen lumbar vertebrae were obtained from 8 cadavers. Pedicle screws were instrumented on each level using CBT under video recording. After the instrumentation, X-ray images were obtained, and anatomical dissections were performed. RESULTS: To be able to reach a necessary angle for medial to lateral CBT trajectory, 13 out of 19 (68%) spinous processes had to be removed. There were a total of seven complications. One pars and pedicle fracture out of 37 trajectories (2.7%) and 6 out of 37 trajectory deviations (16.2%), which resulted in gross loosening, were observed. CONCLUSIONS: The head of the pedicle screw impinging on the base of spinous process and lamina was observed in our cadaveric model. This mechanism could potentially explain both screw loosening and fractures associated with the CBT technique.

Adaptive remodeling at the pedicle due to pars fracture: a finite element analysis study.

OBJECT: Spondylolysis is a common condition among the general population and a major cause of back pain in young athletes. This condition can be difficult to detect with plain radiography and has been reported to lead to contralateral pars fracture or pedicle fracture in the terminal stages. Interestingly, some patients with late-stage spondylolysis are observed to have radiographic or CT evidence of a sclerotic pedicle on the side contralateral to the spondylolysis. Although computational studies have shown stress elevation in the contralateral pedicle after a pars fracture, it is not known if these changes would cause sclerotic changes in the contralateral pedicle. The objective of this study was to investigate the adaptive remodeling process at the pedicle due to a contralateral spondylolysis using finite element analysis. METHODS: A multiscale finite element model of a vertebra was obtained by combining a continuum model of the posterior elements with a voxel-based pedicle section. Extension loading conditions were applied with or without a fracture at the contralateral pars to analyze the stresses in the contralateral pedicle. A remodeling algorithm was used to simulate and assess density changes in the contralateral pedicle. RESULTS: The remodeling algorithm demonstrated an increase in bone formation around the perimeter of the contralateral pedicle with some localized loss of mass in the region of cancellous bone. CONCLUSIONS: The authors' results indicated that a pars fracture results in sclerotic changes in the contralateral pedicle. Such a remodeling process could increase overall bone mass. However, focal bone loss in the region of the cancellous bone of the pedicle might predispose the pedicle to microfractures. This phenomenon explains, at least in part, the origin of pedicle stress fractures in the sclerotic contralateral pedicles of patients with unilateral spondylolysis.