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Migrated interbody


Introduction

Transforaminal lumbar interbody interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF) have become common procedures for the treatment of degenerative lumbar disease such as spondylolisthesis, scoliosis, and spondylosis leading to foraminal stenosis. Interbody cage placement is often used to increase fusion rate and stabilization of the instrumented segments. While this has shown to be advantageous to patient outcomes and fusion rates, migration of the interbody can occur following interbody cage placement. While the interbody cage can migrate both anteriorly and posteriorly, the concerns differ depending on the direction of migration. For anterior migration, the main concerns are injury of the great vessels and bowel perforation, especially in grafts with ongoing migration or placed too far anteriorly. For posterior migration, the main concerns are nerve root compression, cauda equina syndrome, and spinal deformity. Although many small cohort studies exist looking at the risk of migration, a recent meta-analysis by Liu et al. found that pear-shaped disks and straight cages were the main risk factors for cage migration. Here, we discuss the approach to a posteriorly displaced cage migration causing deformity.

Example Case

  • Chief complaint: leg and back pain

  • History of present illness: A 52-year-old female with a history of L3-5 TLIF 2 years prior presents with back pain and leg pain. Immediately after surgery 2 years prior, the patient had worsening back pain and inability to stand up straight. She continued to have worsening back pain. She eventually had a magnetic resonance image (MRI) and was found to have kyphoscoliosis with migration of her L4-5 interbody cage posteriorly into the canal ( Fig. 19.1 ). She was also noted to have hardware loosening on computed tomography (CT) ( Fig. 19.2 ) and a kyphotic deformity on x-rays ( Fig. 19.3 ).

    Fig. 19.1, Preoperative magnetic resonance images. (A) T2 sagittal and (B) T2 axial images demonstrating L4-5 kyphosis with interbody graft migration.

    Fig. 19.2, Preoperative computed tomography scans. (A) Sagittal and (B) L4-5 kyphosis with interbody graft migration and resulting grade I spondylolisthesis of L4-5 with hardware at L4-5.

    Fig. 19.3, Preoperative x-rays. (A) Anteroposterior (AP) and (B) lateral x-rays demonstrating coronal and sagittal imbalance.

  • Medications: sumatriptan

  • Allergies: no known drug allergies

  • Past medical and surgical history: back pain, L3-L5 TLIF

  • Family history: noncontributory

  • Social history: nurse, no smoking history, occasional alcohol

  • Physical examination: awake, alert, and oriented to person, place, and time; cranial nerves II–XII intact; bilateral deltoids/triceps/biceps 5/5; interossei 5/5; iliopsoas/knee flexion/knee extension/dorsi, and plantar flexion 5/5

  • Reflexes: 2+ in bilateral biceps/triceps/brachioradialis with negative Hoffman; 2+ in bilateral patella/ankle; no clonus or Babinski; sensation intact to light touch

  • Todd J. Albert, MD

  • Orthopaedic Surgery

  • Hospital for Special Surgery

  • Weill Cornell Medical College

  • New York, New York, United States

  • Dean Chou, MD

  • Rory Mayer, MD

  • Neurosurgery

  • University of California at San Francisco

  • San Francisco, California, United States

  • Fabio Cofano, MD

  • Neurosurgery

  • University of Turin

  • Spine Surgery Unit

  • Humanitas Gradenigo HospitalTurin, Italy

  • Luis Rodrigo Diaz Iniguez, MD

  • Orthopaedic Surgery

  • Hospital Angeles Lindavista

  • Mexico City, Mexico

Preoperative
Additional tests requested DEXA

  • DEXA (3–6 months of teriparatide if osteopenic or osteoporotic)

  • L-spine flexion-extension x-rays

  • Medicine evaluation

  • DEXA

  • Previous x-rays

  • L-spine flexion-extension x-rays

  • DEXA

  • Parathyroid hormone level

  • Calcium metabolism evaluation

Surgical approach selected

  • Stage 1: posterior exploration

  • Stage 2: revision and removal of anterior L4-S1 cages

  • Stage 3: posterior fusion

  • Stage 1: L4-5 ALIF with cage retrieval, L5-S1 ALIF;

  • Stage 2: T10-pelvis posterior fusion with posterior column osteotomies and possible L4 PSO

  • Step 1: L3-L5 intersomatic arthrodesis after cage removal

  • Stage 2: L5-S1 ALIF

  • Stage 3: L3-S1 posterior reinstrumentation and fusion

L4-5 interbody removal, L2-S1 posterior fusion and L4-5 interbody replacement
Goal of surgery Decompression, and restore sagittal and coronal alignment Cage retrieval, correction of sagittal and coronal alignment, fusion across pseudoarthrosis Restore sagittal and coronal alignment with resolution of pain, achievement of stable fusion Decompression, stabilize spine, improve sagittal balance
Perioperative
Positioning

  • Stage 1: prone

  • Stage 2: supine

  • Stage 3: prone

  • Stage 1: supine on flat top Jackson table

  • Stage 2: prone on proaxis table

  • Stage 1: right lateral

  • Stage 2: supine with slight Trendelenburg

  • Stage 3: prone with hip extension

Prone
Surgical equipment

  • IOM (MEP/SSEP/EMG)

  • Fluoroscopy

  • BMP

  • IOM (MEP/SSEP/EMG)

  • Fluoroscopy

  • Surgical navigation

  • Cell saver

  • IOM

  • Fluoroscopy

  • IOM

  • Fluoroscopy

  • Vertebroplasty set

Medications Tranexamic acid, paraspinal blocks Tranexamic acid None Steroids, Pregabalin
Anatomical considerations Nerve roots, dura, anterior vasculature

  • Stage 1: iliac vessels, aortic bifurcation, ureter

  • Stage 2: dura, right L4 and L5 nerve roots, scar tissue

Psoas, lumbar plexus and vessels, iliac vessels Dura, nerve root, vertebral body, bone density
Complications feared with approach chosen Instrument failure, CSF leak, vascular injury, pseudoarthrosis CSF leak, nerve root injury, pseudoarthrosis Vascular injury, lumbar plexus injuries, inability to remove cages, durotomy Neurological injury, vertebral fracture
Intraoperative
Anesthesia General General General General
Exposure

  • Stage 1: L4-S1

  • Stage 2: L3-S1

  • Stage 3: L4-S1

  • Stage 1: L4-S1

  • Stage 2: T10-pelvis

  • Stage 1: L3-L5

  • Stage 2: L5-S1

  • Stage 3: L3-S1

L2-S1
Levels decompressed L4-S1 L4-S1 L3-L5 L4-5
Levels fused L3-S1 T10-pelvis L3-S1 L2-S1
Surgical narrative

  • Stage 1: position prone, open previous posterior midline incision, subperiosteal dissection, explore hardware, remove pedicle screws from L4-S1 and rods, place new instrumentation with upsized instrumentation from L4-S1 with possible iliac fixation depending on purchase and bone quality, prepare fusion bed, obtain local bone graft, temporary closure

  • Stage 1: position supine, vascular surgery access, abdominal incision, retroperitoneal approach to anterior spine, mobilization of great vessels, expose L4-5 and L5-S1 disc spaces, discectomy at L4-5 with use of Cobb to aggressively distract disc space and mobilize cage for retrieval, placement of interbody cage at L4-5, discectomy and ALIF at L5-S1, avoid placement of any screw through buttress plate or integrated screw/plate into L4 vertebral body because of planned L4 PSO

  • Stage 1: left lateral approach for L3-L4 and L4-L5, dissect abdominal wall to reach retroperitoneal space, transpsoas approach to the L3-L4 and L4-L5 disc with aid of IOM, remove transforaminal cages by distracting disc spaces with spreader devices, position trabecular titanium cage trying to reach anterior part of disc space to achieve proper lordosis

  • Stage 2 (same day): position supine, anterior retroperitoneal approach to L5-S1 disc space, careful discectomy with proper preparation of bony end plates, position hyper lordotic cage based on spinopelvic parameters

Position prone, midline skin incision, plane dissection to transpedicular system, remove rods, remove L5 pedicle screws, remove interbody, reduce the listhesis, reposition interbody in L4-5 space, place pedicle screws at L2 and L5-S1, contour rod to restore lumbar lordosis to improve sagittal balance, x-ray to confirm alignment and hardware location, layered closure

  • Stage 2 (same day): position supine, vascular surgery to expose L3-S1 by retroperitoneal approach, remove L4-5 cage, remove L3-4 case if not solid, distract L4-5/L5-S1/possible L3-4, place large footprint lordotic cases with BMP for lordosis from L3-S1, layered closure

  • Stage 3 (same day): position prone, open incision from stage 1, place rods, lock down, layered closure with subfascial drain

  • Stage 2 (2–3 days after stage 1): position prone, thoracolumbar incision, explant prior implants at L3-5, O-arm spine and navigated pedicle screw placements from T10-pelvis except for L4, perform posterior column osteotomies at L3-S1 to see if enough lordosis can be achieved, PSO if need more lordosis by placing short L3 and L5 screws that are buried deeper into the pedicles relative to the other pedicles, place L3-5 accessory rods across PSO site and separate rod construct T10-pelvis excluding L3 and L5 screws, expose dura from the pedicle of L3 to pedicle of L5, isolate L4 pedicles, PSO, closure of osteotomy with proaxis table, final tighten L3-5 accessory rods, size and place primary rods from T10-pelvis, use coronal bender for correction of coronal deformity, final tighten set screws, layered closure with two subfascial drains

  • Stage 3 (same day): position prone, open old incision, remove screws and reposition at L3-S1 bilaterally, posterior osteotomy of L5, compression between screws after rod positioning

Complication avoidance Stage 1 to upsize instrumentation with potential iliac fixation depending on purchase and bone quality, stage 2 exposure done by vascular surgery, lordotic cases from L3-S1, three staged approach Stage 1 approach by vascular surgery, avoid anterior screws into L4 vertebral body, start with posterior column osteotomies to increase lordosis, PSO if need more lordosis, four-rod construct, coronal plane bender for coronal plane deformity Three-stage approach, IOM to guide transpsoas approach, place cage as anterior as possible to promote lordosis, place hyperlordotic cage based on spinopelvic parameters Reduce the listhesis, extend construct, replace hardware, contour rods to be more lordotic
Postoperative
Admission ICU ICU ICU Floor
Postoperative complications feared Infection, hematoma, medical complication CSF leak, nerve root injury, bony fracture when retrieving cage CSF leak, lumbar plexus injuries, infections Neurological injury, vertebral fracture, infection
Anticipated length of stay 4–6 days 7 days 4–5 days 7 days
Follow-up testing

  • AP/lateral lumbar x-rays prior to discharge

  • AP/lateral/flexion/extension lumbar x-rays 3 months after surgery

  • EOS entire spine 3 months after surgery

Standing scoliosis x-rays prior to discharge, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery Standing x-rays within 24 hours after surgery, 1, 3, 6, and 12 months after surgery

  • L-spine x-rays prior to discharge

  • MRI L-spine 2 months after surgery

Bracing Light lumbar wrap when out of bed and ambulating for 3–4 weeks None Semirigid brace for 30 days Jewett brace for 2 months
Follow-up visits 3–4 weeks 2 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery 1, 3, 6, and 12 months after surgery 2 weeks after surgery
ALIF , Anterior lumbar interbody fusion; AP, anteroposterior; BMP , bone morphogenic protein; CSF , cerebrospinal fluid; DEXA , dual-energy x-ray absorptiometry; EMG , electromyography; ICU , intensive care unit; IOM , intraoperative monitoring; MEP , motor evoked potential; MRI , magnetic resonance imaging; PSO , pedicle subtraction osteotomy; SSEP , somatosensory evoked potentials.

Differential diagnosis

  • ▪

    Interbody migration

  • ▪

    Pseudoarthrosis

  • ▪

    Hardware failure

  • ▪

    Adjacent segment disease

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