Treatment of Degenerative Lumbar Scoliosis with Minimally Invasive Multilevel LLIF in Combination with Lateral ALIF

50 Treatment of Degenerative Lumbar Scoliosis with Minimally Invasive Multilevel LLIF in Combination with Lateral ALIF

James E. Dowdell, Giuseppe Barbagallo, and Sheeraz Qureshi

Summary

Adult degenerative lumbar scoliosis (ADLS) contributes to significant disability and decrease in quality of life. Minimally invasive spine surgery has seen many advancements over recent years. New surgical techniques allow for spine deformity correction in a minimally invasive fashion. Here we present a case of ADLS that was treated with a combined lateral lumbar interbody fusion (LLIF) and lateral position anterior lumbar interbody fusion (ALIF) with posterior percutaneous fixation.

Keywords: lateral ALIF MIS XLIF MIS deformity degenerative scoliosis adult deformity

50.1 Introduction

Adult degenerative lumbar scoliosis (ADLS) is a progressive condition characterized by asymmetrical intervertebral disc degeneration, facet hypertrophy, loss of lumbar lordosis, and deformity in the coronal and sagittal planes.1^,² The prevalence of degenerative scoliosis ranges from 6 to 68% in the elderly population.¹^,²^,³ The etiology of this condition is thought to be multifactorial. One theory is that this condition arises from asymmetric load applied to the lumbar spine over time, while another theory implicates osteoporosis because ADLS is most common in the elderly female population (over 50 years of age). ADLS frequently presents as an isolated lumbar curve, unlike adult idiopathic scoliosis. There is a rotatory deformity present at the apex of the lumbar curve and there is frequently lateral subluxation of the vertebral body as well.³

Increased attention has been paid to the impact of degenerative scoliosis on the aging population with the increasing focus of quality of life outcome measures. ADLS contributes to significant pain and disability for patients. Frequently, nonoperative treatment fails in symptomatic patients. Unlike adolescent idiopathic scoliosis (AIS), degenerative scoliosis can progress at a rate of 3 degrees per year.²^,³ Historically, ADLS has been treated nonoperatively secondary to perioperative morbidity, high incidence of neurological deficit, rigidity of deformity, and difficulty of the surgery. However, with the advent of new fusion techniques, treatment for degenerative scoliosis is now commonplace.¹^,²^,³

50.2 Preoperative Presentation

Most patients with ADLS present with a chief complaint of pain. The pain can be both axial or radicular in nature. The axial back pain is activity related and is the result of muscular fatigue. Often this pain is relieved with rest and is exacerbated by prolonged upright standing. Patients will also frequently complain of pain overlying muscular insertions around the iliac crest, spinous processes, and sacrum. Radicular pain and neurogenic claudication will often impact the patient simultaneously. Overgrowth of facets and ligamentum hypertrophy can produce symptoms of neurogenic claudication. Radicular pain can be the result of direct compression of the nerve root by a disc herniation, traction of the nerve root on the convexity of the deformity, or compression of the nerve root on the concavity of the deformity. Due to the unstable nature of the spine, the radicular pain associated with the deformity will often be worse with standing or walking.³ Cosmetic deformity is generally well tolerated in the elderly population, but this can be a presenting sign as well.

50.3 Imaging Studies

All patients who are undergoing preoperative workup for surgical correction for ADLS should have either an anteroposterior (AP) and a lateral scoliosis radiograph or an EOS radiograph if available. EOS imaging will expose the patient to less radiation and are often higher quality and easier to interpret and thus is the imaging modality of choice in our practice. There are a variety of radiographic measurements that will be calculated on these imaging studies. Cobb angles will be measured on the AP radiograph to assess the deformity in the coronal plane, and sagittal parameters are measured on the lateral radiograph.⁴ In our practice, these parameters are measured easily with the assistance of a surgical planning software called Surgimap.⁵ Pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, and the sagittal vertical axis (SVA) are all measured automatically with Surgimap. Bending films may be utilized to assess both the flexibility of the curve and the compensatory ability of adjacent levels. However, bending films are more commonly used in AIS as patients with degenerative lumbar scoliosis frequently have very stiff deformities.³

Advanced imaging is useful to evaluate bony anatomy, the intervertebral discs, and ligamentum flavum. This allows for evaluation of central, lateral recess, and foraminal stenosis in addition to any disc herniation. A lumbar CT scan is useful for assessment of bony anatomy and in most cases it will be obtained. A lumbar MRI is somewhat difficult to interpret in the setting of a degenerative lumbar scoliosis secondary to the obliquity of the vertebral body and the three-dimensional nature of the deformity. MRI is still useful for evaluation of stenosis, assessment of ligamentum hypertrophy, and disc herniation and should be obtained prior to any planned surgical intervention.³

50.4 Indications for Surgery

Proper indications for surgery will increase the chance for a successful outcome. There are multiple potential surgical options for treatment of adult degenerative lumbar scoliosis. Very infrequently will an isolated decompression be performed secondary to the risk of rapid decompensation and destabilization of the degenerative curve.³ Depending on the preoperative symptoms of the patient, an instrumented fusion with or without decompression can be performed. Traditional posterolateral spinal fusion in the setting of degenerative scoliosis has a high rate of pseudoarthrosis without the use of interbody devices.¹^,²^,³

Interbody devices have been used to decrease the rates of pseudoarthrosis.6 There are a variety of methods for placing interbody devices: Posterior lumbar interbody fusion (PLIF), anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), oblique lateral interbody fusion (OLIF), and transforaminal lumbar interbody fusion (TLIF); each has unique advantages and disadvantages. PLIF often does an inadequate job of restoring lumbar lordosis and carries the risk of injury to nerve roots secondary to excessive retraction.⁶ TLIF, similar to PLIF, often does not adequately restore lumbar lordosis.⁶ ALIF is suitable for the L4–L5 and L5–S1 levels, but carries significant risk at more cephalad lumbar levels secondary to extensive peritoneal retraction and risk of superior mesenteric artery thrombosis.⁶ The use of ALIF in the setting of degenerative lumbar scoliosis has the advantage of offering extensive correction of lumbar lordosis and lower pseudoarthrosis rates secondary to maximal fusion surface area for fusion.⁶ However, due to ALIF being limited to lower lumbar levels it is most useful as an adjunct to other interbody techniques in degenerative scoliosis. LLIF is useful for access to the interbody disc space from T12–L1 down to L4–L5 and allows for the correction of both sagittal and coronal deformities, but is not useful in the setting of severe central canal stenosis or lateral recess stenosis.⁶ OLIF allows for access to the L5–S1 level from the lateral position by accessing the disc space anterior to the psoas musculature and this option also allows for correction of significant sagittal and coronal deformities.⁶ OLIF is contraindicated in the setting of severe central canal stenosis.

There are no consensus guidelines to develop a surgical plan in the setting of symptomatic degenerative lumbar scoliosis, but there is a recent publication that can help guide decision-making when choosing minimally invasive spine deformity correction.⁷ Patients presenting with adult degenerative lumbar scoliosis will often have many medical comorbidities including obesity, anemia, diabetes, and osteoporosis. These conditions favor the use of minimally invasive techniques such as LLIF and ALIF/OLIF by preventing extensive dissection and stripping of paraspinal musculature.⁸ Patients tend to have quicker in-hospital recoveries with MIS techniques.

50.5 Case Presentation

A 61-year-old female presented with axial back pain for the past several years, which had significantly worsened over the last 1 to 2 years. The patient has significant walking intolerance and must stop after walking about two city blocks. She is also presenting with bilateral buttocks pain that is claudicatory in nature. The patient denies any medical comorbidities and she has no smoking history. Over the past 2 years, the patient has attempted nonsteroidal anti-inflammatory drugs (NSAIDs), physical therapy, acupuncture, and epidural steroid injections (ESI) with initial relief. However, nonoperative modalities were no longer helping the patient with her pain. The patient had a normal neurological examination with palpable pedal pulses. Her only symptomatic finding on physical examination is pain with back extension.

The patient had obtained full-length EOS imaging, which showed an LL of 29 degrees and a PI of 56 degrees for a PI-LL mismatch of 27 degrees (Fig. 50.1a, b). The patient was sent for a lumbar MRI, which showed multilevel foraminal stenosis as well as lateral recess/central canal stenosis which was moderate at L4–L5 and L5–S1 (Fig. 50.2, Fig. 50.3, Fig. 50.4, Fig. 50.5). The goals of treatment for this patient include a restoration of age-adjusted pelvic parameters through hyperlordotic interbody cages and indirect decompression of foraminal stenosis through minimally invasive techniques to minimize morbidity and allow quicker recovery.