Summary Pediatric Spondylolysis & Spondylolisthesis represent a continuum of disease where there is a fracture of the pars interarticularis (spondylolysis) which may progress to anterior subluxation of one vertebral body anterior to the adjacent inferior vertebral body (spondylolisthesis). Diagnosis of spondylolysis alone can be challenging on imaging and the ideal study is controversial. Radiographs, CT scan, and MRI may all play a role. Spondylolisthesis is diagnosed on a lateral radiograph. Treatment may be nonoperative or surgical depending on the degree of back pain, malalignment of vertebral bodies, and neurological symptoms. Epidemiology Incidence common up to 6-7% of adolescent athletes implicated in up to 47% of low back pain complaints in this population Demographics higher incidence in Native Americans Anatomic location typically involves pars of L5 and anterolisthesis of L5 relative to S1 Risk factors prevalence of spondylolysis may be as high as 47% in certain athletes (gymnasts, weightlifters, football linemen) contact sports and those involving repetitive hyperextension (ex. linebacker) higher sacral table index, pelvic incidence, sacral slope, and lower sacral table angle Etiology Pathophysiology conditions represent a continuum of disease including pars stress reaction defined as sclerosis of pars without complete bone disruption spondylolysis defined as a complete fracture of the pars interarticularis mechanism defects are not present at birth and develop over time (seen in 4-6% if population) usually activity related and occurs from repetitive hyperextension isthmic spondylolisthesis (spondylolytic spondylolithesis) defined as forward translation of one vertebral segment over the one beneath it due to a pars defect risks of progression approximately 15% of individuals with a pars interarticularis lesion have progression to spondylolisthesis the larger the slip the more likely it is to progress > Myerding 2 (>50% slip) dysplastic slips (Wiltse Type I) are more likely to progress severity of current slip correlates most strongly with pelvic incidence spondyloptosis 100% translation of one vertebra over the next caudal vertebra Genetics possible autosomal dominant inheritance pattern Classification Wiltse-Newman Classification Type I Dysplastic Secondary to congenital abnormalities of lumbosacral articulation including mal-oriented or hypoplastic facets, sacral deficiency, poorly developed pars Posterior elements are intact (no spondylolysis) More significant neurologic symptoms Type II-A Isthmic - Pars Fatigue Fx Type II-B Isthmic - Pars Elongation due to healed stress fx Type II-C Isthmic - Pars Acute Fx Type III Degenerative Type IV Traumatic Type V Neoplastic Marchetti-BartolozziClassification Developmental Includes Wiltse I and II Acquired Traumatic, postsurgical, pathologic, degenerative Meyerding Classification Grade I < 25% Grade II 25-50% Grade III 50-75% Grade IV 75-100% Grade V Spondyloptosis Presentation History classic history is healthy active adolescent who presents with acute onset of low back pain with athletic activity Symptoms asymptomatic many cases of spondylolysis are asymptomatic low back pain no association between radiologic grade and clinical presentation symptoms include insidious onset of activity related low back pain leg symptoms buttock pain hamstring tightness (most common) and knee contracture radicular pain (L5 nerve root) listhetic crisis severe back pain aggravated by extension and relieved by rest neurologic deficit hamstring spasm bowel and bladder symptoms rare cauda equina syndrome (rare) Physical exam inspection high grade/dysplastic patients may develop "heart shaped buttocks" due to sacral prominence flattened lumbar lordosis palpation palpable step off of spinous process motion limitation of lumbar flexion and extension measure popliteal angle to evaluate for hamstring tightness neurovascular straight leg raise may be positive rectal exam if bowel and bladder symptoms present provocative tests pain with single-limb standing lumbar extension gait may walk with a crouched gait when symptoms severe Imaging Pars stress reaction & spondylolysis radiographs indications AP and lateral indicated in all patients with concern for spondylolysis and spondylolithesis AP view may see sclerosis of the stress reaction lateral view may show defect in pars in 80% oblique view views may show sclerosis and elongation in pars interarticularis (scotty dog sign) some studies have shown that oblique does not provide more diagnostic information than AP and lateral radiographs but does increase radiation exposure CT inidcations best study to delineate anatomy of lesion findings pars stress reaction will show up as sclerosis on x-rays and CT scan single photon emission computer tomography (SPECT) indications previously considered the best diagnostic adjunct when plain radiographs are negative; however, now rarely performed given unnecessary radiation exposure can also detect osteoid osteomas, sacroiliitis, osteitis pubis, and disc herniation techniques combines technique of bone scan with CT in order to help localize an area of abnormal activity seen on bone scan MRI indications negative ragdiographs with high suspicion very acute presentation any neurological deficits sensitivity & specificity recent studies have shown MRI to be as sensitive and specific as SPECT, with the additional benefit of avoiding radiation exposure bone scan indications excellent screening tool for low back pain in children or adolescents sensitivity & specificity most sensitive (however lesion may be cold) Spondylolisthesis radiographs views lateral x-ray used to measure slip angle and grade. flexion and extension radiographs used to evaluate instability measurements slip grade slippage on plain lateral radiographic imaging measured in accordance to the vertebra below the caudal vertebra is divided into four parts Grade I means a translation of the cranial vertebra of up to 25% Grade II of up to 50% Grade III of up to 75% Grade IV up to 100% Grade V describes the ptosis of the cranial vertebra slip angles methodology to determine slip angle most important determinant for nonunion and pain angle >45-50 degrees associated with greater slip progression, instability, and development of post-op pseudo pelvic incidence pelvic incidence = pelvic tilt + sacral slope a line is drawn from the center of the S1 endplate to the center of the femoral head a second line is drawn perpendicular to a line drawn along the S1 endplate, intersecting the point in the center of the S1 endplate the angle between these two lines is the pelvic incidence (see angle X in figure above) correlates with severity of disease pelvic incidence has direct correlation with the Meyerding–Newman grade pelvic tilt pelvic tilt = pelvic incidence - sacral slope a line is drawn from the center of the S1 endplate to the center of the femoral head a second vertical line (parallel with side margin of radiograph) line is drawn intersecting the center of the femoral head the angle between these two lines is the pelvic tilt (see angle Z in figure above) sacral slope sacral slope = pelvic incidence - pelvic tilt a line is drawn parallel to the S1 endplate a second horizontal line (parallel to the inferior margin of the radiograph) is drawn the angle between these two lines is the sacral slope (see angle Y in the figure above) CT best study to diagnose and delineate anatomy of pars defect MRI indicated if neurologic symptoms present useful to diagnose associated central and foraminal stenosis Treatment Nonoperative observation alone (no activity limitations) indications asymptomatic patients regardless of slip grade which does not correlate with clinical presentation return to in contact sports is controvesial limited evidence to guide surgeons following surgical management, decision must be individualized some data shows patients who stop sports for at least 3 months have improved outcomes compared to those who continue to play outcomes typically do well and remain asymptomatic physical therapy & activity restriction indications symptomatic isthmic spondylolysis symptomatic low-grade spondylolisthesis technique physical therapy should be done for 6 months and include hamstring stretching pelvic tilts abdominal strengthening outcomes most improve and do not require surgery watch low grade dysplastic carefully as there is a higher chance of progression bracing for 6 to 12 weeks indications acute pars stress reaction spondylolysis isthmic spondylolysis that has failed to improve with physical therapy low grade spondylolisthesis that has failed to improve with physical therapy technique typically a TLSO outcomes brace immobilization is superior to activity restriction alone for acute stress reaction spondylolysis Operative pars interarticularis repair indications L1 to L4 isthmic defect that has failed nonoperative management multiple pars defects outcomes typically superior to fusion procedures, preserves motion L5-S1 posterolateral fusion, +/- ALIF, +/- sacroiliac fusion indications L5 spondylolysis that has failed nonoperative treatment low grade spondylolisthesis (Myerding Grade I and II) that has failed nonoperative treatment is progressive has neurologic deficits is dysplastic due to high propensity for progression return to sport some evidence to support that ALIF may help return to competetitive sports most surgeons allow return to noncontact sports 3-6 months following fusion and return to contact sports 6-12 months (controversial) outcomes patients typically do well and return to sport in 3-6 months L4-S1 posterolateral fusion, +/- reduction, +/- sacroiliac fusion, +/- ALIF indications high grade spondylolytic spondlylisthesis (Meyerding Grade III, IV, V) reduction is extremely controversial with no accepted guidelines outcomes patients typically do well but may have greater motion limitations with multi-level fusion over-aggressive reduction techniques may result in neurologic impairments Techniques Par interarticularis repair approach posterior midline approach to lumbar spine technique repair pars defect with screw fixation, tension wiring, or screw and sublaminar hook technique decompression indicated if clinical symptoms of stenosis contraindications disc degeneration (obtain MRI for sx planning) L5-S1 posterolateral fusion +/- ALIF approach posterior midline approach to lumbar spine technique decompression only indicated if clinical symptoms of stenosis or radiculopathy in-situ fusion with bone grafting / with or without instrumentation postoperative usually postoperative immobilization in a TLSO L4-S1 posterolateral fusion, +/- reduction, +/- sacroiliac fusion, +/- ALIF approach posterior midline approach to lumbar spine technique reduction reduction may be done with instrumentation or positioning pros of reduction can restore sagittal alignment and reduce lumbosacral kyphosis cons risk of significant complications (8-30%) including L5 is the most common nerve root injury with reduction sexual dysfunction catastrophic neurologic injury fusion/decompression usually instrumented the addition of decompression and anterior-posterior (360 deg) fusion is associated with more in-hospital complications the use of interbody cages in this population has decreased significantly, while costs associated with treatment in general have increased over time Complications Neurologic deficits consider neuromonitoring during reduction, especially in a high-grade slip L5 n. root injury is the most common neuro cx Pseudoarthrosis Slip Progression Hardware failure Prognosis Most symptomatic patients can be successfully managed nonoperatively In patients who fail non-operative management, spinal fusion results in 90% success rates Return to sports is controversial