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Adolescent idiopathic deformity


Introduction

Adolescent idiopathic scoliosis (AIS) is the most common type of scoliosis, affecting 2% to 4% of adolescents with an occurrence rate of 0.5 to 5.2%. Although the pathophysiology is unclear, there are some studies that suggest a genetic component. While smaller curvature is seen in males and females at similar rates, there is a higher prevalence of larger curvature in women. Additionally, around the time of puberty, there is a significant increase in the female-to-male ratio of scoliosis (8.4:1), suggesting there may also be a role of sex hormones in the development of this type of scoliosis. Patients typically present with back deformity and shoulder asymmetry, which can also be seen in the waistline and rib prominence. Although the majority of symptoms are cosmetic, patients can occasionally present with back pain and even decreased lung capacity in severe cases.

Example Case

  • Chief complaint: back pain

  • History of present illness: A 19-year-old male presents with a history of back pain that worsens with activity. He was diagnosed with AIS and has been managed conservatively. Over the past 7 months, he has been having severe back pain with activity that is relieved with rest. He has noted some postural change in this time. His mother has also noted some scapular bulging over the past 3 years. He underwent imaging and this revealed concern for progressive scoliosis ( Figs. 37.1–37.2 ).

    Fig. 37.1, Preoperative magnetic resonance images. (A) , T2 sagittal and (B) , T2 oblique sagittal images demonstrating severe thoracolumbar scoliosis.

    Fig. 37.2, Preoperative x-rays. (A) , Lateral, (B) , left-bending, (C) , right-bending, and (D) , anteroposterior x-rays demonstrating a Lenke 6CN thoracolumbar scoliosis.

  • Medications: atomoxetine, cetirizine, methylphenidate

  • Allergies: codeine

  • Past medical and surgical history: attention-deficit/hyperactivity disorder

  • Family history: noncontributory

  • Social history: student, nonsmoker

  • 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

  • Dean Chou, MD

  • Rory Mayer, MD

  • Neurosurgery

  • University of California at San Francisco

  • San Francisco, California, United States

  • Christopher J. Dewald, MD

  • Orthopaedic Surgery

  • Rush University Medical Center

  • Chicago, Illinois, United States

  • Takeshi Hara, MD

  • Neurosurgery

  • Juntendo University

  • Hongo, Bunkyo-ku, Tokyo, Japan

  • Yasuaki Tokuhashi, MD

  • Orthopaedic Surgery

  • Nihon University

  • Oyaguchi Kamicho, Itabashi-ku, Tokyo, Japan

Preoperative
Additional tests requested

  • Pulmonary function test

  • Psychosocial assessment

  • Physical therapy evaluation

MRI complete spine

  • MRI C-spine

  • CT T-L spine

  • Pulmonary function test

  • Flexion-extension x-rays

  • 3D CT

Surgical approach selected T3-L4 fusion with posterior column osteotomies at T8-10 and T12-L3 T4-L4 fusion with single posterior column osteotomy T3-L3 posterior fusion with Ponte osteotomies as needed Stage 1: T11-L3 posterior releaseStage 2: T11-L3/L4 anterior correction and fusion

  • Surgical approach if 50

  • Surgical approach if 80

  • Same approach

  • Same approach

  • Same approach

  • Same approach

  • Same approach

  • Same approach

  • Same approach, minimize levels

  • Stage 1: L2-3 to L4-5 OLIF

  • Stage 2: T6-Iliac (7 days later)

Goal of surgery Halt curve progression, prevent pulmonary compromise, improve cosmetic deformity, potentially decrease back pain Halt curve progression, partial correction of deformity, spinal cord safety Coronal balance Correct deformity, stabilize spine
Perioperative
Positioning Prone on Jackson table, no pins Prone on Jackson table, Gardner-Wells tongs Prone, no pins

  • Stage 1: prone on Hall frame

  • Stage 2: right decubitus position

Surgical equipment

  • IOM

  • Osteotome

  • IOM (MEP/SSEP)

  • Fluoroscopy

  • IOM (MEP)

  • O-arm

  • Surgical navigation

  • IOM (MEP/SSEP)

  • Osteotome

Medications Tranexamic acid Tranexamic acid Maintain MAP None
Anatomical considerations Spinal cord/thecal sac Spinal cord, nerve roots, dysplastic vertebrae Aorta, inferior vena cava, spinal cord, nerve roots

  • Stage 1: facet joints

  • Stage 2: major vessels, ureter, neural structures, pleura

Complications feared with approach chosen Neurological deficit, pseudoarthrosis, adjacent segment disease Spinal cord injury, blood loss, pseudoarthrosis, adjacent segment degeneration Spinal cord injury, vascular injury, nerve root injury

  • Stage 1: paravertebral damage

  • Stage 2: injury to major vessels/ureter, screw malposition, screw back out at correction, neural injury at correction

Intraoperative
Anesthesia General General General General
Exposure T3-L4 T4-L4 T3-L3 T11-L3
Levels decompressed None None None None
Levels fused T3-L4 T4-L4 T3-L3 T11-L3/4
Surgical narrative Position prone, expose posterior elements from T3 to L4, place pedicle screws at T3 to L4 after confirmation of levels with x-ray, reduction screws placed at apex of curve, posterior column osteotomies with facet resection bilaterally from T7-T10 and T12-L3, place working rod that is contoured and placed on concavity of curve and provisionally secured with set screws at cephalad and caudal ends, gradual tightening of the reduction screw to bring spine to the rod, axial derotation as necessary to address rib hump, confirm with IOM stability of signals, release correction if any IOM changes, secure rod with set screws, further coronal correction with coronal plane benders, placement of convexity rod with placement of set screws, further axial derotation done with second rod in place, final tightening of screws after additional distraction/compression maneuvers as necessary to achieve correction, decortication of exposed lamina and placement of local autograft, layered closure with two subfascial drains Preflip IOM, position prone with Gardner-Wells tongs, add weights to tongs (15 lb), midline posterior incision from T4 to L4, subperiosteal exposure of spinous processes, expose T4-L4 transverse processes using monopolar cautery and Cobb elevator, inferior facetectomies from T4 to L3 bilaterally using osteotome, determine mobility of spinal deformity, place pedicle screws using anatomy with fluoroscopic confirmation starting in lumbar spine and proceeding superiorly, drop screws that are not needed in the middle of construct (pedicles too small or are missed), Ponte osteotomies from T11/12 to L3/4 by removing spinous processes down to ligamentum flavum and exposing superior facets, run MEP, place precontoured rods, utilize rod rotation and cantilever maneuvers to obtain spinal deformity correction in both coronal and sagittal planes, derotation using vertebral derotation tubes, lock correction with set caps and run MEP, decorticate exposed lamina and transverse processed from T4 to L4, place local and allograft bone throughout, use to cross-links, layered closure with drains, neurological check before extubation and leaving the operating room Position prone, midline incision, remove soft tissue and extend dissection to transverse processes, insert pedicle screws from T3 to L3 with O-arm navigation, use polyethylene cables if pedicles are too small or difficult to insert, place multiaxial reduction screws in apex vertebra in the lumbar curve on concave side and fixed screws on caudal side, attach vertebral column manipulation instruments to fixed screws on concave and convex sides, resect inferior articular processes, perform Ponte osteotomy is necessary for lumbar curve, apply compression force on convex side and apply rotational force in the opposite direction of vertebral body rotation with traction on concave side, apply cobalt chromium alloy rods on both sides once sufficient deformity correction achieved making sure thoracic rods are kyphotic and lumbar spine lordotic, apply pressure to convex side and traction on concave side, final tighten set screws and polyethylene tape, layered closure

  • Stage 1: position prone, longitudinal midline incision from T11 to L3, expose T11/T12 to L2/3 facet joints, T11-L2 partial inferior facet resection and cartilage curettage by osteotome and diamond bur, standard closure, position change

  • Stage 2: right decubitus position, curved incision along the 10th rib, 10th rib resection, expose T11-L3 veretebral body by incising diaphragm, T11/12 to L2-3 disc resection, T11-L3 anterior plate Snad screws, pack tips of resected rib into disc space, rod and screw fixation from T11-L3 to correct coronal curve slowly, fix anterior rods and screws, compress between posterior screws to correct sagittal lordosis, posterior rods and screws are fixed, closure with chest tube if necessary

Complication avoidance Place reduction screws at apex of curve, axial derotation to address rib hump, IOM while curve correction, coronal plane benders to reduce coronal deformity Preflip IOM, remove screws in middle of construct that are not needed, utilize rod rotation and cantilever maneuvers to obtain spinal deformity correction in both coronal and sagittal planes O-arm and surgical navigation for pedicle screws, use polyethylene cables if pedicles are too small or difficult to insert, perform Ponte osteotomy is necessary for lumbar curve Two stages, dual rods, slow correction of coronal followed by sagittal curves, chest tube if necessary
Postoperative
Admission Floor ICU ICU ICU
Postoperative complications feared Neurological deficit, pseudoarthrosis, adjacent segment disease with potential need to extend fusion to pelvis in future Neurological deficit, pseudoarthrosis, spinal imbalance, pain Spinal cord or nerve root injury, CSF leak, spinal instability, aorta or vena cava injury Hemothorax, ileus, injury to major vessels or ureter
Anticipated length of stay 4–5 days 3–5 days 10–14 days 10–14 days
Follow-up testing Standing scoliosis x-rays at discharge, 6 weeks, 3 months, 6 months, 1 year, 2 years after surgery Standing scoliosis x-rays 3 weeks after surgery CT T-L spine within 24 hours, 3 months after surgery CT scan 7 days, 6 months after surgery
Bracing None None Corset for 3 months Hard corset for 6 months
Follow-up visits 2 weeks, 6 weeks, 3 months, 6 months, 1 year, 2 years after surgery 3 weeks after surgery 2 weeks, 3 months after surgery 4 weeks after surgery
APP , Advanced practice provider; BAERs , brainstem auditory evoked responses; CT , computed tomography; DEXA , dual-energy x-ray absorptiometry; ERAS , enhanced recovery after surgery; ESI , epidural spinal injections; ICU , intensive care unit; IOM , intraoperative monitoring; MAP , mean arterial pressure; MEP , motor evoked potential; MRI , magnetic resonance imaging; SSEP , somatosensory evoked potential.

Differential diagnosis

  • Adolescent idiopathic scoliosis

  • Neuromuscular scoliosis

  • Degenerative scoliosis

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