summary Adult spinal deformity is an idiopathic or degenerative condition of the adult spine that leads to deformity in the coronal or sagittal plane Diagnosis is made with full-length spine radiographs Nonoperative treatment is a trial of NSAIDs and physical therapy. Surgical deformity correction is indicated for progressive disabling pain that has failed nonoperative management and/or progressive neurological deficits Epidemiology Demographics mean age 60 y/o males and females equally affected Anatomic location idiopathic scoliosis occurs more commonly in the thoracic spine degenerative scoliosis occurs more commonly in the lumbar spine Etiology Types coronal plane imbalance defined as lateral deviation of the normal vertical line of the spine >10° sagittal plane imbalance defined as radiographic sagittal imbalance >5 cm Pathoanatomy degenerative scoliosis results from the asymmetric degeneration of disc spaces and/or facet joints in the spine may occur in the coronal plane (scoliosis) or the sagittal plane (kyphosis/lordosis) factors contributing to loss of sagittal plane balance osteoporosis preexisting scoliosis iatrogenic instability degenerative disc disease Classification Coronal deformity can be broken down into idiopathic (residual) ASD results from untreated adolescent idiopathic scoliosis in adults degenerative (de novo) ASD defined as a progressive deformity in the adult caused by degenerative changes iatrogenic injury paralysis Idiopathic (Residual) vs. Degenerative (De Novo) ASD Idiopathic (Residual) Degenerative (De Novo) Curve pattern Follows classic curve patterns Lacks classic curve patterns Vertebral segments Involves more vertebral segments Involves fewer vertebral segments Curve location Thoracic spine Lumbar spine Curve magnitude Larger curve magnitudes Smaller curve magnitudes Presentation Symptoms low back pain (40-90%) most common symptom caused by spondylosis, micro/macroinstability, and discogenic pain more severe and recurrent than in the general population neurogenic claudication pain in lower extremities and buttocks login to view 1 more bullet caused by spinal stenosis login to view 1 more bullet radicular leg pain and weakness caused by foraminal and lateral recess stenosis worse in the concavity of the deformity where there is vertebral body rotation and translation Physical exam deformity with thoracic prominence seen with forward bending compensatory postural changes muscle weakness Imaging Radiographs recommended views full-length 36-inch cassette standing scoliosis radiographs in coronal (AP radiograph) and sagittal plane (lateral radiograph), with right and left bending films login to view 1 more bullet measurements AP radiograph login to view 3 more bullets lateral radiograph login to view 5 more bullets CT scan identify bony deformity, such as facet arthrosis CT myelogram most useful for assessing stenosis and bony anatomy, as rotation makes interpretation of MRI difficult better appreciation of bony anatomy and rotational deformity than MRI MRI indicated when lower extremity pain is present can identify central canal stenosis facet hypertrophy pedicle enlargement foraminal encroachment disc degeneration DEXA scan determine bone density for surgical planning Treatment Nonoperative observation with nonoperative modalities indications login to view 1 more bullet modalities login to view 9 more bullets Operative surgical curve correction with instrumented fusion general indications login to view 8 more bullets technique login to view 10 more bullets Techniques General goals of surgery restore spinal balance login to view 7 more bullets relieve pain obtain solid fusion worse outcomes associated with: baseline depression obesity Selecting proximal and distal fusion levels proximal extension extend to a neutral and horizontal vertebra above the main curve extend fusion to L5 indications login to view 2 more bullets outcomes login to view 1 more bullet extend fusion to sacrum (S1) indications login to view 17 more bullets extend fusion to ilium (sacropelvic fusion) indications login to view 1 more bullet technique login to view 1 more bullet outcomes login to view 5 more bullets cement augmentation indications login to view 1 more bullet technique login to view 1 more bullet outcomes login to view 4 more bullets Osteotomies overview useful to regain sagittal balance in severe angulation deformities 30°+ correction can be obtained through Smith-Petersen or pedicle subtraction osteotomies intraoperative neuromonitoring is preferred Smith-Petersen osteotomy (SPO) indications login to view 2 more bullets prerequisites login to view 4 more bullets pedicle subtraction osteotomy (PSO) indications login to view 3 more bullets vertebral column resection indications login to view 6 more bullets Anterior procedures indications large curves >70° rigid curves (no flexibility on side bending films) isolated lumbar or thoracolumbar curves anterior interbody fusion at L5-S1 when fusing to sacrum technique anterior release and fusion usually combined with posterior instrumentation and fusion login to view 1 more bullet outcomes disadvantages login to view 3 more bullets advantage login to view 2 more bullets Complications (surgical) Overall overall complication rate ~13.5% 10% major complications that often irreversibly affect the long-term health of the patient complication rates are significantly higher with osteotomies, revision procedures, and combined anterior/posterior approaches venous thromboembolism is most likely to result in poor clinical outcomes following adult spinal deformity surgery Pseudoarthrosis incidence (~5-25%) most common surgical technique resulting in pseudoarthrosis is posterior only fusion (15%) most common locations L5-S1 thoracolumbar junction risks >55 y/o kyphosis >20° positive sagittal balance >5 cm hip arthritis smoking thoracoabdominal approach incomplete lumbopelvic fixation osteoporosis Dural tear (~2.9%) Infection deep wound infection (~1.5%) superficial wound infection (~0.9%) increased risk with diabetes, smoking, increasing age, and revision surgery Implant complication instrumentation failure is more likely in bone with the lowest ratio of cortical to cancellous bone (sacrum < vertebral bodies < lumbar pedicles < thoracic pedicles) most common cause of reoperation; related to pseudoarthrosis lower rates of mechanical complications with GAP scores <3 Neurologic deficits acute neurological deficits (~1%) can occur intraoperatively after deformity correction maneuver if identified on neurophysiologic monitoring, remove instrumentation and consider a wake-up test delayed neurological deficits (~0.5%) acute neurological deficits following PSO (18%) nerve root injury screw malposition corrective maneuver Epidural hematoma (~0.2%) Pulmonary embolus (~0.2%) Deep venous thrombosis (~0.2%). Deaths (~0.3%) Prognosis Worse prognosis symptoms progress to the side of the curve convexity sagittal plane imbalance sagittal plane balance is the most reliable predictor of clinical symptoms in adults with spinal deformity Progression depends on curve type thoracic > lumbar > thoracolumbar > double major right thoracic curves (1° per year) right lumbar curves (0.5° per year) thoracolumbar curves (0.25° per year) depends on curve magnitude curves <30° rarely progress curves >50° commonly progress additional risk factors for progression increased risk when intercrestal line is below L4-5 preexisting rotational changes