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Emergency and Acute Medicine: Spondylolysis and Spondylolisthesis
Spondylolysis is a structural defect in the pars interarticularis, the portion of bone between the superior and inferior articular facets of a vertebra. This defect may occur on one side or both sides, with bilateral involvement significantly increasing the risk of progression to spondylolisthesis, a condition in which one vertebra slips forward over the one beneath it. Spondylolisthesis affects approximately 5% of the population and is more common in males. About half of patients with spondylolysis will develop some degree of vertebral slippage, and roughly half of those individuals will experience symptoms. This condition often leads to nerve root compression, frequently causing sciatica.
Spondylolisthesis is categorized based on underlying cause and severity. Etiologic types include congenital (dysplastic), stress-related (isthmic), degenerative, traumatic, and pathologic forms. Severity is graded using the Meyerding classification, ranging from Grade I (≤25% slippage) to Grade IV (75–100%). The most commonly affected level is L5 slipping over S1, followed by L4 over L5. In pediatric populations, spondylolysis is a common cause of significant low back pain, particularly during adolescent growth spurts. It is frequently seen in young athletes engaged in sports involving repetitive spinal extension, such as gymnastics, diving, and football.
The exact cause of spondylolysis remains uncertain but is thought to involve a combination of congenital susceptibility, altered bone density, and repetitive microtrauma. Symptoms usually develop gradually, unless triggered by acute injury. Patients commonly report low back pain associated with muscle stiffness or spasms, which may radiate to the proximal legs. Pain is typically worsened by standing, walking, or hyperextension and relieved by sitting or forward bending. Neurologic symptoms are generally absent unless significant vertebral displacement leads to nerve compression.
On physical examination, patients may demonstrate a hyperlordotic posture with a shortened trunk appearance and tight hamstrings. A classic diagnostic maneuver is the one-legged hyperextension test, where standing on one leg and leaning backward reproduces pain on the affected side. In more advanced cases, a palpable step-off may be detected over the lumbar spine. Neurologic examination is usually normal but may reveal dermatomal sensory or motor deficits if nerve involvement is present.
Diagnosis is primarily radiologic. Plain lumbosacral spine radiographs, especially oblique views, may reveal a defect in the pars interarticularis, often described as the “Scottie dog” sign with a “broken neck.” Lateral views help identify vertebral slippage. CT scanning provides more detailed visualization of bony abnormalities and is useful in evaluating fracture acuity and healing, while MRI can assess nerve root compression and other soft tissue pathology. In children, imaging is pursued more readily due to the higher risk of progression.
Management is typically conservative. Treatment focuses on pain control, activity modification, and gradual return to activity once symptoms improve. Patients are advised to avoid activities involving repetitive spinal extension for several weeks. Physical therapy and, in some cases, bracing may be considered. Surgical intervention, usually spinal fusion, is reserved for patients with severe symptoms, high-grade slippage (Grade III or IV), or those who fail conservative therapy.
Medications may include NSAIDs, muscle relaxants, and, when necessary, short-term opioids for pain control. Hospital admission is indicated for patients who are unable to ambulate, cannot manage pain at home, or develop new or worsening neurologic deficits. Most patients can be managed as outpatients with appropriate follow-up and education. Pediatric patients require especially close monitoring due to the higher likelihood of progression.
Important pitfalls include missing the diagnosis in adolescents with persistent back pain, failing to recognize progressive neurologic deficits, and overlooking alternative diagnoses such as infection, tumor, or disc disease. Early identification and appropriate management are key to preventing progression and long-term complications.
Spondylolysis is a structural defect in the pars interarticularis, the portion of bone between the superior and inferior articular facets of a vertebra. This defect may occur on one side or both sides, with bilateral involvement significantly increasing the risk of progression to spondylolisthesis, a condition in which one vertebra slips forward over the one beneath it. Spondylolisthesis affects approximately 5% of the population and is more common in males. About half of patients with spondylolysis will develop some degree of vertebral slippage, and roughly half of those individuals will experience symptoms. This condition often leads to nerve root compression, frequently causing sciatica.
Spondylolisthesis is categorized based on underlying cause and severity. Etiologic types include congenital (dysplastic), stress-related (isthmic), degenerative, traumatic, and pathologic forms. Severity is graded using the Meyerding classification, ranging from Grade I (≤25% slippage) to Grade IV (75–100%). The most commonly affected level is L5 slipping over S1, followed by L4 over L5. In pediatric populations, spondylolysis is a common cause of significant low back pain, particularly during adolescent growth spurts. It is frequently seen in young athletes engaged in sports involving repetitive spinal extension, such as gymnastics, diving, and football.
The exact cause of spondylolysis remains uncertain but is thought to involve a combination of congenital susceptibility, altered bone density, and repetitive microtrauma. Symptoms usually develop gradually, unless triggered by acute injury. Patients commonly report low back pain associated with muscle stiffness or spasms, which may radiate to the proximal legs. Pain is typically worsened by standing, walking, or hyperextension and relieved by sitting or forward bending. Neurologic symptoms are generally absent unless significant vertebral displacement leads to nerve compression.
On physical examination, patients may demonstrate a hyperlordotic posture with a shortened trunk appearance and tight hamstrings. A classic diagnostic maneuver is the one-legged hyperextension test, where standing on one leg and leaning backward reproduces pain on the affected side. In more advanced cases, a palpable step-off may be detected over the lumbar spine. Neurologic examination is usually normal but may reveal dermatomal sensory or motor deficits if nerve involvement is present.
Diagnosis is primarily radiologic. Plain lumbosacral spine radiographs, especially oblique views, may reveal a defect in the pars interarticularis, often described as the “Scottie dog” sign with a “broken neck.” Lateral views help identify vertebral slippage. CT scanning provides more detailed visualization of bony abnormalities and is useful in evaluating fracture acuity and healing, while MRI can assess nerve root compression and other soft tissue pathology. In children, imaging is pursued more readily due to the higher risk of progression.
Management is typically conservative. Treatment focuses on pain control, activity modification, and gradual return to activity once symptoms improve. Patients are advised to avoid activities involving repetitive spinal extension for several weeks. Physical therapy and, in some cases, bracing may be considered. Surgical intervention, usually spinal fusion, is reserved for patients with severe symptoms, high-grade slippage (Grade III or IV), or those who fail conservative therapy.
Medications may include NSAIDs, muscle relaxants, and, when necessary, short-term opioids for pain control. Hospital admission is indicated for patients who are unable to ambulate, cannot manage pain at home, or develop new or worsening neurologic deficits. Most patients can be managed as outpatients with appropriate follow-up and education. Pediatric patients require especially close monitoring due to the higher likelihood of progression.
Important pitfalls include missing the diagnosis in adolescents with persistent back pain, failing to recognize progressive neurologic deficits, and overlooking alternative diagnoses such as infection, tumor, or disc disease. Early identification and appropriate management are key to preventing progression and long-term complications.
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