Continuing Education Activity

Spondylolysis refers to a posterior defect in the vertebral body at the pars interarticularis. Usually, this defect is due to trauma or from a chronic repetitive loading and hyperextension. If this instability results in translation of the vertebral body, spondylolisthesis has occurred. This process requires a fracture or deformation of the posterior spine elements creating an elongation of the pars. This condition occurs in all ages with the underlying cause varying based on the age group. This activity describes the pathophysiology, evaluation, and management of lumbar spondylolysis/spondylolisthesis and highlights the role of the interprofessional team in improving care for affected patients.

Objectives:

• Identify the different types of spondylolisthesis, differentiating the patholological features that distinguish each variety.
• Outline the components of a proper evaluation and assessment of a patient presenting with lumbar spondylolysis/spondylolisthesis, including any indicated imaging studies.
• Describe management strategies for spondylolisthesis, based on which variant of the condition with which the patient presents.
• Review the interprofessional team strategies for improving care coordination and communication regarding the management of patients with lumbar spondylolysis/spondylolisthesis.

Introduction

Spondylolysis refers to a posterior defect of the vertebral body occurring at the pars interarticularis.[1] Typically, this defect results from trauma or chronic repetitive loading and hyperextension. If this instability leads to translation of the vertebral body, this is spondylolisthesis.[1][2] This process requires either a fracture or deformation of the posterior spinal elements resulting in elongation of the pars interarticularis. This condition can potentially occur in all age groups, with the underlying cause varying based on age. If the slip progresses to the point of neurologic compromise, then surgical intervention may be necessary to decompress and stabilize affected segments.[3] Absent any motor deficits, a nonoperative course of analgesia, activity modification, and injections should be the initial therapeutic approach for several months.[4]

Etiology

Isthmic spondylolisthesis refers to a defect within the pars interarticularis usually from repetitive microtrauma and accounts for the vast majority of cases in children and adolescents.[1][5] 

Degenerative spondylolisthesis is the most common form of spondylolisthesis seen in adults.[6] It is due to chronic degenerative changes at the posterior elements resulting in the incompetence of the surrounding ligamentous structures, leading to elongation and slippage.[6]

Acutely, a traumatic spondylolisthesis can occur following a high-energy injury flexion/extension that causes a fracture-dislocation at the posterior elements.[7] 

Another type is dysplastic spondylolisthesis which is a result of an abnormal formation of the posterior elements resulting in this subsequent instability.[8]

Epidemiology

The rates of spondylosis and spondylolisthesis vary widely by age group. In the pediatric population, spondylosis is present in about 5% of the population, most commonly (90%) at the L5 to S1 motion segment, although pathology at L4 is more likely to be symptomatic.[1][9] Long-term studies estimate that about 15% of those with a defect (spondylosis) will develop a slip (spondylolisthesis).[10][11] Regarding adults, lumbar spondylolisthesis without a defect in the pars is present in 5% of men, 10% of women.[12] It is not always symptomatic. This degenerative type usually occurs at the L4 to L5 levels (versus isthmic noted at L5 to S1).[6] Degenerative spondylolisthesis is an acquired type of spondylolisthesis occurring much more frequently and gradually in the adult population.[6] Cohorts with degenerative spondylolisthesis will rarely develop a high-grade spondylolisthesis.[13] Furthermore, the chronic natural history of this disease process is such that with further degenerative changes, the vertebral segments may eventually stabilize, and the patients can have subsequent clinical improvements.[13]

Pathophysiology

Repetitive micro-traumas from hyperextension lead to elongated or absent pars interarticularis. This force applies additional stress to the facet joints and subsequent hypermobility leading to advanced degeneration of the disc space.[14] The reduced disc and facet stability results in the translation of the vertebral body, creating a stenotic effect on the exiting nerve roots and/or the spinal canal. In the traumatic setting, flexion-distraction energy may cause a localized vertebral body failure at this segment, predisposing the patient to chronic issues if instability develops.

History and Physical

Initial evaluation of lower back pain initiates by obtaining a history from the patient. This history should pertain to the timeline of pain, radiation of pain, and inciting events. The clinician should pay careful attention to prior episodes of trauma. Low-grade slips and stenotic spinal canals may decompress and relieve pain with leaning forward or sitting. It is crucial to note patient comments such as decreased pain with pushing a grocery cart or walking upstairs as both common actions have the spinal column in forwarding flexion.[15] It is also important in any evaluation of extremity issues to inspect circulation as vascular claudication may mirror or mimic the neurogenic problems.

Classically patients may complain of pain radiating down both buttocks and lower extremities. An evaluation of the patient's walking is also critical to better assess the daily impact that pain or neurological deficits cause. All physical examinations will include assessing the neurologic function of the arms, legs, bladder, and bowels. The keys to a thorough exam are organization and patience. One should evaluate not only strength but also sensation and reflexes. It is also essential to inspect the skin along the back and document the presence of tenderness to compression or palpable step-off.  

Performing a straight leg test in a patient positioned supine may also reveal a stenotic canal.[16] This test may also cause local sites of pain as hamstring contractures are often associated with spondylolisthesis.[17] As mentioned above, a thorough neurologic examination is required. Commonly a patient will have L5 radiculopathy resulting in weakness of ankle dorsiflexion and extension of the great toe. This deficit may also diminish the Achilles tendon reflex. L4 radiculopathy may present with weakness at the quadriceps and a decreased patellar tendon reflex.

Documentation is paramount as these initial findings will likely serve as a baseline for all future evaluations.

Evaluation

Evaluation of patients with low-back pain typically includes anterior-posterior (AP) and lateral radiographs of the impacted area. Some physicians will obtain radiographs of the entire spine. A key component to radiographic evaluation is obtaining flexion/extension films, which illustrates vertebral segment stability.[18]  Serial standing lateral radiographs obtained in the clinic will help track any potential progression of the slip.

One of the crucial measurements to note regarding slips is the amount of translation between vertebral bodies. The amount of “uncovering” of one endplate from the other determines the grade. There are four grades of spondylolisthesis: Grade 1: 0% to 25%, Grade 2: 26% to 50%, Grade 3: 51% to 75% and Grade 4: 76% to 99%.[12][19] At 100% displacement, patients have developed spondyloptosis.[20] Grades 1 and 2 are considered low-grade slips.[21] Grades 3 and 4 are considered high-grade spondylolisthesis.[19]

An MRI is critical when evaluating patients with suspected spondylosis and spondylolisthesis. Frequently these patients will initially trail a six-week course of physical therapy. Upon follow-up, if the symptomology is still present, the clinician can obtain an MRI at that time.[1] The focus should be on the T2 weighted sagittal and axial images, as these will illustrate any compression of neurologic elements.

Treatment / Management

Non-surgical intervention includes modification of the activity that may have exacerbated the pain, non-steroidal anti-inflammatory medications (NSAIDs), physical therapy, stretching, and occasionally using a lumbosacral orthosis. A 2009 meta-analysis evaluating spondylolysis and grade 1 spondylolisthesis showed almost 84% of adolescent patients treated nonoperatively had a successful clinical outcome at one year.[22] This study also showed no difference in those who did and did not use a brace.[22] Likely it is the activity restriction and not bracing, which determines the overall outcome. Additionally, a course of at least six weeks of physical therapy with an emphasis on core exercise strengthening and stretching should be attempted. Additionally, temporary pain relief is possible with epidural injections, but the potential for subsequent infection risk, while low, is possible.[23][24] 

While most patients improve with nonoperative treatment alone, those failing a conservative treatment course have three options- continued pain, complete avoidance of activities that elicit pain, or surgical intervention. Again, the surgical options for spondylolysis (as well as low-grade spondylolisthesis) should be reserved for those with either neurologic deficits, the progression of a slip, or pain limiting daily functions.[3] The literature regarding the optimal surgical procedure, approach, and roles for decompression and instrumentation remains controversial. While there is still controversy regarding the need for posterior decompression for patients who have just radicular symptoms, what is agreed upon is the need for decompression when a true motor deficit is present.[3][11][25] Additionally, in the setting of retrolisthesis and disc herniation at L5-S1, recent long-term follow-up from the SPORT database has shown non-inferior outcomes in patients with surgically treated disc herniations in the setting of retrolisthesis.[26] The patient needs to understand that while surgical intervention has favorable outcomes for relieving radicular pains, the results are less predictable for non-radiating lower back pain.

Differential Diagnosis

• Lumbosacral disc injuries

• Lumbosacral discogenic pain syndrome

• Lumbosacral facet syndrome

• Lumbosacral spine acute bony injuries

• Lumbosacral spine sprain/strain injuries

• Lumbosacral spondylolisthesis

• Lumbosacral spondylosis

• Myofascial pain in athletes

• Sacroiliac joint injury

Prognosis

The prognosis for patients with spondylolisthesis is generally good. Most patients will respond to conservative treatment. For those with ongoing, severe symptoms not relieved by conservative approaches, surgery can potentially relieve radicular leg symptoms by decompressing nerve roots. Localized lumbar pain may require lumbar fusion in more extreme cases.[27][28]

Complications

Complications of spondylolisthesis tend to be neurological. These can include chronic pain in the lower back or legs, and numbness, tingling, or weakness in the lower extremities. Severe nerve compression can lead to problems with bowel or bladder control; however, this is quite uncommon.[27]

Deterrence and Patient Education

Patients will need to understand their condition and its imposed limitations based on the severity of their particular case. The clinician should review the relevant anatomy and explain the disruption, using spinal models if necessary. A review of the patient's activities and physical demands is prudent (e.g., heavy lifting, prolonged sitting, etc.). Based on the severity of the condition, the clinician may impose physical limitations.

Pearls and Other Issues

Many patients will improve with a nonoperative treatment course directed at activity modification.[22] Patients should understand that surgery frequently will not relieve all pain as irreversible damage to the nerves may have already occurred. The future of minimally invasive treatment options will continue to perfect outcomes for spinal stenosis. Advancements in pain control and endoscopic technologies now allow for select patients and facilities to perform endoscopic disc debridement followed by percutaneous instrumentation on an outpatient basis. Additional research will focus on optimizing treatment outcomes and predicting which patients will develop symptomatic progression of a slip.

Enhancing Healthcare Team Outcomes

Patients with low back pain are best managed by an interprofessional team that includes the emergency department physician, therapist, orthopedic nurse, primary care physician, an orthopedic surgeon. The initial treatment for low back pain is non-surgical and involves a change in lifestyle. Most patients can benefit from exercise, weight loss, and leading an active lifestyle. Surgery is only a recommendation when there is nerve compression, or the patient has failed conservative treatment. The patient must understand that surgery is not always effective, and many patients still experience residual pain and limited range of motion of the lumbar spine. The patient needs to understand that while surgical intervention has favorable outcomes for relieving radicular pains, the results are less predictable for non-radiating lower back pain.