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Chapter Summary
• Context: Spondylolysis and spondylolisthesis in the pediatric population represent lumbosacral junction disorders ranging clinically from asymptomatic incidental radiographic findings to high-grade deformities accompanied by severe sagittal imbalance, back pain, radiculopathy, and marked functional disability. Spondylolysis denotes a structural osseous defect in the pars interarticularis, whereas spondylolisthesis defines the actual anterior vertebral slippage. Pathophysiology is multifactorial, involving repetitive mechanical stress, local vertebral dysplastic anatomy, spinopelvic morphology, genetic predisposition, and athletic activities involving hyperextension and rotation. Most low-grade forms follow a benign clinical course, but the risk of progressive slippage escalates during rapid skeletal growth spurts and in dysplastic spinopelvic configurations. The chapter underscores that contemporary evaluation must transcend the simple percentage of vertebral slippage: lumbosacral kyphosis, pelvic orientation, and global sagittal balance dictate clinical severity and are central to choosing between observation, in situ fusion, and surgical reduction.
• Chapter Objective: To present the anatomical, pathophysiological, clinical, and radiographic foundations of pediatric spondylolysis and spondylolisthesis. The reader will recognize distinct disease patterns, select appropriate imaging modalities, master the Meyerding and Spinal Deformity Study Group (SDSG) classification systems, evaluate spinopelvic balance and lumbosacral kyphosis, and understand the principles guiding conservative therapy, direct pars repair, in situ fusion, reduction, and the prevention of neurological complications.
• Spondylolysis and spondylolisthesis as growth-related disordersThe chapter interprets spondylolysis as a stress fatigue fracture of the pars interarticularis occurring in individuals predisposed by genetic and morphologic factors. Bipedal posture, lumbar lordosis, and athletic activities combining hyperextension and rotation concentrate mechanical stress on the L5-S1 junction. High pelvic incidence and sagittal facet orientation exacerbate this biomechanical vulnerability. Progressive vertebral slippage occurs predominantly during pediatric growth spurts and becomes uncommon following skeletal maturity. Consequently, biological age and remaining growth potential must be evaluated even in asymptomatic patients.
• Clinical presentation and postural compensationLow-grade cases are frequently asymptomatic. When pain occurs, it typically presents as activity-related low back pain relieved by rest. High-grade slippage often associates with radicular pain, neurogenic claudication, and, rarely, sphincter dysfunction. As lumbosacral kyphosis worsens, characteristic postural compensations develop: hyperlordosis, pelvic retroversion, hip/knee flexion, and a crouched gait. Figure 1 demonstrates the Phalen-Dickson sign, the clinical hallmark of this severe sagittal imbalance. Hamstring tightness, illustrated in Figure 2, is another classic physical finding.
• Imaging: selecting the right modality for each questionStanding full-spine radiographs represent the essential foundation to quantify slippage, measure lumbosacral kyphosis, and assess global spinopelvic balance. The chapter discourages routine oblique radiographs due to added radiation without significant clinical gain. Computed tomography (CT) details pars bony architecture and dysplastic anatomy in complex cases (Figure 4). SPECT/CT aids in distinguishing acute healing stress lesions from chronic pseudarthrosis. Magnetic resonance imaging (MRI) avoids ionizing radiation, identifies early marrow bone stress edema, and evaluates neural compression (Figure 3).
• Classifying beyond the percentage of slippageThe Meyerding classification (Figure 5) provides a simple grading of translational slip percentage (Grades I to V). Wiltse-Newman-Macnab and Marchetti-Bartolozzi add etiological and dysplastic insight. The chapter assigns primary clinical significance to the SDSG classification (Figures 7 and 8), which integrates slip grade, pelvic incidence, pelvic tilt, and global sagittal balance. Lumbosacral kyphosis (slip angle, Dubousset lumbosacral angle in Figure 6) emerges as the pivotal parameter governing functional severity.
• Treatment guided by symptoms, progression risk, and balanceMost pediatric low-grade lesions are successfully managed conservatively with activity modification, core physical therapy, temporary bracing, and serial radiographic follow-up through skeletal maturity. Surgery is reserved for intractable pain, documented progression, neurological deficits, or high-grade deformities. Options include direct pars repair (e.g., Buck, Scott, or Morscher techniques) in select young patients, in situ fusion, and surgical reduction with spinopelvic reconstruction. The authors emphasize that in high-grade dysplastic cases, correcting lumbosacral kyphosis and restoring global spinopelvic balance takes precedence over achieving anatomic translational reduction.
• Clinical Application: In clinical practice, an incidental pars defect identified during back pain workup must not be reflexively assumed to be the pain generator without rigorous clinical correlation. In growing children, even mildly symptomatic spondylolisthesis requires scheduled radiographic surveillance if dysplastic anatomy or high pelvic incidence indicates elevated progression risk. Full-spine standing radiographs are essential to capture how spine, pelvis, and lower extremities interact. The SDSG classification organizes patients by slip grade and spinopelvic balance (balanced vs unbalanced pelvis/spine), guiding appropriate treatment pathways. Low-grade isthmic spondylolisthesis starts with conservative measures (activity modification, hamstring stretching, core stabilization). When surgery is indicated, direct pars repair preserves motion in young patients with intact L5-S1 discs. In high-grade slips, surgical strategy centers on restoring sagittal balance and correcting lumbosacral kyphosis. Aggressive translational reduction carries a high risk of L5 nerve root stretch neuropraxia; the priority is correcting regional kyphosis (slip angle), decompressing L5 roots, and achieving solid circumferential spinopelvic fusion (L4-S1/pelvis) with intraoperative neuromonitoring.
