Gene Cheh

Adult spinal deformity surgery : Complications and outcomes in patients over age 60

Study Design. A retrospective analysis, including prospectively collected patient outcomes data. Objective. To determine the rate of complications and outcomes in patients ≥60 years of age who underwent major spinal deformity surgery requiring a minimum 5-level arthrodesis procedure. Summary of Background Data. As the population ages, an increasing number of older patients are presenting with spinal deformity disorders that may require major reconstructive procedures. Previous studies have reported complication rates as high as 80% in this age group for 1- and 2-level fusion procedures. The prevalence of complications was found to increase with the greater number of levels fused. Methods. Forty-six patients who were 60 years of age or older underwent a thoracic or lumbar arthrodesis procedure consisting of 5 levels or greater. Diagnosis, comorbidities, operative data, hospital data, major and minor complications, and deaths were recorded. Oswestry Disability Index (ODI) Scores were used to evaluate clinical outcomes. Results. Thirty-eight females and 8 males with a mean age of 67 years (range, 60–85 years) and a mean follow-up of 4.2 years (range, 2–11 years) had complete records. Thirty-six (78%) patients had at least 1 comorbidity. Twenty-nine (63%) patients had at least 1 prior spinal surgery. A mean of 9 levels (range, 5–16 levels) were fused in each patient. The overall complication rate was 37%. The major complication rate was 20%. ODI improved from 49 to 25 for a mean improvement of 24 (49%) (P < 0.0001). Conclusion. The overall complication rate was 37% and the major complication rate was 20%. Increasing age was a significant factor (P < 0.05) in predicting the presence of a complication. Patients older than 69 years had more complications. The presence of a comorbidity had no association with complication rates and neither had an effect on final patient reported outcomes, which showed significant improvement (ODI preoperative, 49; postoperative, 25) (P < 0.0001).

Adjacent segment disease followinglumbar/thoracolumbar fusion with pedicle screw instrumentation: a minimum 5-year follow-up.

Study Design. Retrospective radiographic outcomes analysis. Objective. We had 3 hypotheses: 1) a longer fusion; 2) a more proximal instrumented vertebra, and 3) circumferential fusion versus posterior-only fusion would increase the likelihood of adjacent segment disease (ASD). Summary of Background Data. The literature analyzing risk factors, prevalence, and presentation of patients with ASD is varied and without clear consensus. Methods. A total of 188 patients with minimum 5-year follow-up who had lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative disorders were included. Radiographic ASD was defined by: 1) development of spondylolisthesis >4 mm, 2) segmental kyphosis >10°, 3) complete collapse of disc space, or 4) more than 2 grades worsening of Weiner classification. Clinical ASD was defined as 1) symptomatic spinal stenosis, 2) intractable back pain, or 3) subsequent sagittal or coronal imbalance. Results. Radiographic ASD occurred in 42.6% (80 of 188) of patients. Patients with radiographic ASD had worse Oswestry scores (20.3 vs. 12.5; P = 0.001) at ultimate follow-up than those without ASD. Clinical ASD developed in 30.3% (57 of 188) of patients. Clinical ASD manifested as spinal stenosis (n = 47), instability-type back pain (n = 5), and sagittal or coronal imbalance (n = 5). Age at surgery over 50 years and length of fusion were significant risk factors for the development of ASD in the lumbar spine. Fusion to L1–L3 proximally increased the risk of ASD when compared with L4 and L5. Circumferential fusion versus posterior fusion was not a significant factor in the development of ASD. Conclusion. Patients over the age of 50 were at higher risk of developing clinical ASD than those 50 years old or younger. Length of fusion was a significant risk factor in the development of ASD in the lumbar spine. Fusion up to L1–L3 increased the risk of ASD when compared with L4 and L5. Circumferential fusion, as opposed to posterolateral fusion, was not a statistically significant risk factor for the development of ASD.

Results of lumbar pedicle subtraction osteotomies for fixed sagittal imbalance: a minimum 5-year follow-up study.

Study Design. Retrospective study. Objective. To report results at a minimum 5 years after pedicle subtraction osteotomy for fixed sagittal imbalance. Summary of Background Data. No one has reported results of pedicle subtraction osteotomies with a 5- to 8-year follow-up. Method. Thirty-five consecutive patients with sagittal imbalance (29 females/6 males, average age at surgery, 53.1 years) treated with lumbar pedicle subtraction osteotomies (1 at L1, 13 at L2, 20 at L3, and 1 at L4) at 1 institution were analyzed (average follow-up, 5.8 years; range, 5–7.6 years). Radiographic and clinical outcomes analysis was performed. Results. There were no significant regional radiographic changes between 2 years postoperative and the ultimate follow-up (proximal junctional change, P = 0.30; thoracic kyphosis, P = 0.38; and lumbar lordosis, P = 0.84), although many patients did demonstrate an increasingly anterior C7 sagittal plumb with time. Ten pseudarthroses (29%) occurred in 8 patients and were revised between 2 and 5 years postoperative. There were no pseudarthroses at the osteotomy level (9 at the thoracolumbar junction, 1 at the LS junction), but at the levels added to the previous fusions. There was no degradation in Oswestry and Scoliosis Research Society (SRS) outcome scores between 2 years postoperative and ultimate follow-up (P = 0.23 and 0.90, respectively). Patients reported very good satisfaction (87%), good self-image (76%), good function (69%), and fair pain subscales (66%) at ultimate follow-up. Sagittal vertical axis <8 cm at ultimate follow-up was significant for better SRS outcomes scores (P = 0.038). Eight patients with revised pseudarthroses did not demonstrate poorer SRS outcomes scores (P = 0.52). Those 8 patients were queried after their pseudarthrosis revision surgery. Conclusion. Pedicle subtraction osteotomy can provide satisfactory clinical and radiographic outcomes for patients with a minimum 5-year follow-up despite needing pseudarthrosis revision and some component of increasingly positive sagittal vertical axis between 2 years and 5 to 8 years of follow-up. The level of patient satisfaction and self-image subscales were high after more than 5 years of follow-up. Restoration and maintenance of sagittal vertical axis <8 cm were important to the ultimate sagittal reconstruction.

Pseudarthrosis in long adult spinal deformity instrumentation and fusion to the sacrum: prevalence and risk factor analysis of 144 cases.

Study Design. Retrospective study. Objective. To analyze the incidence of and risk factors for pseudarthrosis in long adult spinal instrumentation and fusion to S1. Summary of Background Data. Few studies on pseudarthrosis in long adult spinal instrumentation and fusion to S1 exist. Methods. A clinical and radiographic assessment of 144 adult patients with spinal deformity (average age 52.0 years; range 21.1–77.6) who underwent long (5–17 vertebrae, average 11.9) spinal instrumentation and fusion to the sacrum at a single institution between 1985 and 2002, with a minimum 2-year follow-up (average 3.9; range 2–14) was performed. Results. Of 144 patients, 34 (24%) had pseudarthroses. There were 17 patients who had pseudarthroses at T10–L2 and 15 at L5–S1. A total of 24 patients (71%) presented with multiple levels involved (2–6). Pseudarthrosis was most commonly detected within 4 years postoperatively (31 patients; 94%). Factors that statistically increased the risk of pseudarthrosis were: thoracolumbar kyphosis (T10–L2 ≥20° vs. <20°, P < 0.0001); osteoarthritis of the hip joint (P = 0.002); thoracoabdominal approach (vs. paramedian approach, P = 0.009); positive sagittal balance ≥5 cm at 8 weeks postoperatively (vs. ≤5 cm, P = 0.012); age at surgery older than 55 years (vs. 55 years or younger, P = 0.019); and incomplete sacropelvic fixation (vs. complete sacropelvic fixation, P = 0.020). Fusion from upper thoracic spine (T2–T5) did not statistically increase the pseudarthrosis rate compared to lower thoracic spine (T9–T12) (P = 0.20). Patients with pseudarthrosis had significantly lower Scoliosis Research Society 24 outcome scores (average score 71/120) than those without (average score 90/120; P < 0.0001) at ultimate follow-up. Conclusion. The overall prevalence of pseudarthrosis following long adult spinal deformity instrumentation and fusion to S1 was 24%. Thoracolumbar kyphosis, osteoarthritis of the hip joint, thoracoabdominal approach (vs. paramedian approach), positive sagittal balance ≥5 cm at 8 weeks postoperatively, older age at surgery (older than 55 years), and incomplete sacropelvic fixation significantly increased the risks of pseudarthrosis to an ex-tent that was statistically significant. Scoliosis Research Society 24 outcomes scores at ultimate follow-up were adversely affected when pseudarthrosis developed.

Proximal junctional kyphosis in adult spinal deformity after segmental posterior spinal instrumentation and fusion: minimum five-year follow-up.

Study Design. A retrospective study. Objective. To analyze time-dependent change of, prevalence of, and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity after long (≥5 vertebrae) segmental posterior spinal instrumented fusion with a minimum 5-year postoperative follow-up. Summary of Background Data. No study has focused on time-dependent long-term proximal junctional change in adult spinal deformity after segmental posterior spinal instrumented fusion with minimum 5-year follow-up. Methods. Clinical and radiographic data of 161 (140 women/21 men) adult spinal deformity patients with minimum 5-year follow-up (average 7.8 years, range 5–19.8 years) treated with long posterior spinal instrumentation and fusion were analyzed. Radiographic measurements included sagittal Cobb angle at the proximal junction on preoperative, 8-weeks postoperation, 2-year postoperation, and ultimate follow-up (≥5 years). Postoperative SRS outcome scores were also evaluated. Results. The prevalence of PJK at 7.8 years postoperation was 39% (62/161 patients). The PJK group (n = 62) demonstrated a significant increase in proximal junctional angle at 8 weeks (59%), between 2 years postoperation and ultimate postoperation (35%), and in thoracic kyphosis (T5–T12) at ultimate follow-up (P = 0.001). However, the sagittal vertical axis change at ultimate follow-up did not correlate with PJK (P = 0.53). Older age at surgery >55 years (vs. ≤55 years) and combined anterior and posterior spinal fusion (vs. posterior only) demonstrated significantly higher PJK prevalence (P = 0.001, 0.041, respectively). The SRS outcome scores did not demonstrate significant differences with the exception of the self-image domain when PJK exceeded 20°. Conclusion. The prevalence of PJK at 7.8 years postoperation was 39%. PJK progressed significantly within 8 weeks postoperation (59%) and between 2 years postoperation and ultimate follow-up (35%). Older age at surgery (>55 years) and combined anterior and posterior spinal fusion were identified as risk factors for developing PJK. The SRS outcome instrument was not adversely affected by PJK, except when PJK exceeded 20°.

Proximal junctional kyphosis in adolescent idiopathic scoliosis after 3 different types of posterior segmental spinal instrumentation and fusions: incidence and risk factor analysis of 410 cases.

Study Design. Retrospective study. Objective. Determine proximal junctional kyphosis (PJK) prevalence and analyze risk factors associated with PJK in adolescent idiopathic scoliosis (AIS) patients following 3 different posterior segmental spinal instrumentation and fusion surgeries. Summary of Background Data. No comparison study exists on proximal junctional AIS changes following 3 different segmental posterior spinal instrumentation and fusion surgeries at 2 years postoperative. Methods. A clinical/radiographic assessment was conducted in 410 consecutive AIS patients (average age = 14.7, range = 10.6–20) (men/women = 73/337) treated with instrumented segmental posterior spinal fusion with 2-year follow-up. Revision and anterior cases were not included. Standing long-cassette radiographic measurements were analyzed including various sagittal/coronal parameters for preoperative, early postoperative, and 2-year follow-up. Abnormal PJK was defined by proximal junction sagittal Cobb angles between the lower endplate of the uppermost instrumented vertebra and the upper endplate of 2 supradjacent vertebrae ≥+10° and at least 10° greater than the preoperative measurement at 2 years postoperative. Results. PJK prevalence defined at 2 years postoperative was 27% (111 of 410 patients). Statistically significant factors: larger preoperative thoracic kyphosis angle (T5–T12 >40° vs. T5–T12 10°–40° vs. T5–T12 <10°; P < 0.0001), greater immediate postoperative thoracic kyphosis angle decrease (decrease >5° vs. 5° decrease-5° increase vs. increase >5°; P < 0.0001), thoracoplasty versus no thoracoplasty (P = 0.001), and men versus women (P = 0.007). Instrumentation types (hook-only vs. proximal hook, distal pedicle screw vs. pedicle screw P = 0.058), number of fused vertebrae >12 versus 12≥ (P = 0.12), the uppermost instrumented vertebra among T2, T3, T4, T5 (P = 0.75). There were no significant differences in Scoliosis Research Society Patient Questionnaire-24 outcome-scores (PJK total score = 97.0, self-image subscales = 21.3 vs. non-PJK group = 95.3, 21.0) (P = 0.34 total score, P = 0.54 self-image subscale). Conclusion. Two-year postoperative PJK prevalence in AIS following 3 different posterior segmental spinal instrumentation and fusion surgeries was 27%. A larger preoperative thoracic kyphosis angle, greater immediate postoperative thoracic kyphosis angle decrease, thoracoplasty, and male sex correlated significantly with PJK. There were no significant differences in Scoliosis Research Society Patient Questionnaire-24 outcome-scores between the PJK and non-PJK group.

Operative treatment of adolescent idiopathic scoliosis with posterior pedicle screw-only constructs: minimum three-year follow-up of one hundred fourteen cases.

Study Design. Preoperative review of a prospective study, single institution, consecutive series. Objective. To analyze the intermediate-term follow-up of consecutive adolescent idiopathic scoliosis (AIS) patients treated with pedicle screw constructs. Summary of Background Data. There have been no reports of the intermediate-term findings in North America following posterior spinal fusion with the use of pedicle screw-only constructs. Methods. One hundred and fourteen consecutive patients having a minimum 3-year follow-up (mean 4.8 ± 1.1; range, 3.0–7.3 years) with AIS were evaluated. The average age at surgery was 14.9 ± 2.2 years. Radiographic measurements included preoperative (Preop), postoperative (PO), 2-year (2 years), and final follow-up (FFU). A chart review evaluated PFTs, Scoliosis Research Society scores, presence of thoracoplasty, Risser sign, Lenke classification, and complications. Results. The most frequent curve pattern was Lenke type 1 (45.6%), followed by type 3 (21.9%). The average main thoracic curve measured 59.2° ± 12.2 SD Preop, and corrected to 16.8° ± 9.9 PO (P < 0.0001). Sagittal thoracic alignment (T5–T12) decreased from 25.8° to 15.5° at FFU (P = 0.05). Nash-Moe grading for apical vertebral rotation (AVR) in the proximal thoracic curve decreased from 2.0 Preop to 1.1 at FFU (P < 0.0001), and AVR in the thoracolumbar/lumbar spine decreased from 1.6 Preop to 1.1 at FFU (P < 0.0001). Importantly, the horizontalization of the subjacent disc measured −8.3° Preop which decreased to −0.9° PO (P < 0.001). PFT follow-up averaged 2.4 years with a 7.1% improvement in FVC (P = 0.004) and 8.8% in FEV1 (P < 0.0001). SRS scores averaged 83.0% at latest follow-up. Age, gender, Risser sign, or complications did not have a significant effect on outcomes. There were 2 cases of adding-on, 3 late onset infections, 1 with a single pseudarthrosis, but no neurologic complications. Conclusion. This is the largest (N = 114), consecutive series of North American patients with AIS treated with pedicle screws having a minimum of 3-year follow-up. The average curve correction was 68% for the main thoracic, 50% for the proximal thoracic, and 66% for the thoracolumbar/lumbar curve at final follow-up.

An analysis of sagittal spinal alignment following long adult lumbar instrumentation and fusion to L5 or S1: can we predict ideal lumbar lordosis?

Study Design. A retrospective study. Objective. To determine factors controlling sagittal spinal balance after long adult lumbar instrumentation and fusion from the thoracolumbar spine to L5 or S1. Summary of Background Data. To our knowledge, no study on postoperative sagittal balance following long adult spinal instrumentation and fusion to L5 or S1 has been published. Methods. A clinical and radiographic assessment of 80 patients with adult lumbar deformity (average age 53.4 years) who underwent long (average 7.6 vertebrae, 5–11 vertebrae) segmental posterior spinal instrumentation and fusion from the thoracolumbar spine to the L5–S1 (average 4.5 years, 2–15.8-year follow-up) was performed. We defined the optimal sagittal balance (n = 42) group, the distance from C7 plumb to superior posterior endplate of S1 ≤3.0 cm, and the suboptimal sagittal balance (n = 38) group, the distance from C7 plumb to superior posterior endplate of S1 >3.0 cm at ultimate follow-up. Results. The optimal sagittal balance group (C7 plumb, average −0.6 ± 2.5 cm) had the larger average angle differences between lumbar lordosis and thoracic kyphosis (P < 0.0001), preoperative smaller pelvic incidence (P = 0.007), smaller average thoracolumbar junctional angle (T10-L2) increase (P < 0.0001), and bigger lumbar lordosis angle increase (P = 0.014) at ultimate follow-up. Patients with optimal sagittal balance at ultimate follow-up had significantly higher total Scoliosis Research Society 24 outcome scores than those with suboptimal sagittal balance (P = 0.015). Risk factors that were statistically significant for the suboptimal sagittal balance group included pelvic incidence compared with lumbar lordosis (≥45°) before surgery (vs.— <45°, P = 0.009), smaller lumbar lordosis compared with thoracic kyphosis (<20°) at 8 weeks postoperatively (vs.— ≥20°, P = 0.013), and older than 55 years of age at surgery (vs.— 55 years or younger, P = 0.024). Conclusion. A sagittal Cobb angle difference between lumbar lordosis and thoracic kyphosis of >20° (higher lumbar lordosis) is advisable in most circumstances to achieve optimal sagittal balance.

Evaluation of pedicle screw placement in the deformed spine using intraoperative plain radiographs : A comparison with computerized tomography

Study Design. A retrospective study. Objective. To develop an accurate and reliable method to detect malpositioned pedicle screws during thoracic and lumbar spinal deformity operations using intraoperative plain radiographs. Summary of Background Data. The reliability of pedicle screw assessment using plain radiographs is more difficult during scoliosis operations compared to nondeformed spine operations. Methodology is necessary to document and improve the accuracy of interpretation of intraoperative plain radiographs for deformity surgeries. Methods. A total of 789 pedicle screws, including 632 thoracic and 157 lumbar, inserted from T1 to L4 in 49 patients with spinal deformity with postoperative computerized tomography (CT) data were investigated. According to the diagnoses, the number of screws placed was 683 for scoliosis in 43 patients and 106 for kyphosis in 6 patients. The position of the pedicle screw inserted was graded with CT as an acceptable screw (n = 724) versus violated screw (n = 65), defined as the central axis of the inserted pedicle screw out of the outer cortex of the pedicle wall. There were 3 plain radiographic criteria used to judge the accuracy of screw position after minor screw tip position adjustment according to the relative length of the screws in the lateral radiograph: (1) violation of the harmonious segmental change of the tips of the inserted screws with reference to vertebral rotation using the posterior upper spinolaminar junction in the posteroanterior (PA) radiograph (medial or lateral out); (2) no crossing of the medial pedicle wall by the tip of the pedicle screw inserted with reference to the vertebral rotation using the posterior upper spinolaminar junction in the PA radiograph (lateral out); and (3) violation of the imaginary midline of the vertebral body using the posterior upper spinolaminar junction in the PA radiograph by the position of the tip of the inserted pedicle screw (medial out). Results. Comparative analysis of these pedicle screws using postoperative CT and intraoperative plain radiographs confirmed 65 violated pedicle screws, including 15 medial violations and 50 lateral violations. Of 15 pedicle screws with medial wall violation, 13 showed a loss of harmonious segmental change in the screw tips and violation of the imaginary midline of the vertebral body (sensitivity 0.87, specificity 0.97, and accuracy 0.98). One case showed only a loss of harmonious change in the screw tip, and the other one case did not show any significant plain radiograph findings. Of the 50 pedicle screws with lateral wall violation, 47 cases showed a loss of harmonious segmental change in the screw tips and no crossing of medial pedicle wall by the pedicle screw inserted (sensitivity 0.94, specificity 0.90, and accuracy 0.96). Two cases did not show any significant plain radiograph findings, and the other one case showed only violation of the harmonious segmental change in the screw tips. Conclusions. Intraoperative plain radiographs alone using 3 radiographic criteria were very sensitive to detect lateral wall pedicle screw violations, specific for assessing for medial wall violations, and highly accurate for both. This result confirms the ability of careful intraoperative plain radiographic assessment after pedicle screw insertion to detect malpositioned screws, to allow for possible revision during the index operation.

Computed Tomography Evaluation of Pedicle Screws Placed in the Pediatric Deformed Spine Over an 8-year Period

Study Design. A retrospective review. Objective. To evaluate the incremental accuracy of pedicle screws used in spinal deformity via a free-hand technique at a single institution over an 8-year period. Summary of Background Data. The in vivo accuracy of free-hand pedicle screws placed throughout the deformed spine as evaluated by computed tomography (CT) scanning is unknown over a long time period. Methods. A total of 1023 pedicle screws inserted from T1 to L4 in 60 patients (928 screws in 54 scoliosis patients and 95 screws in 6 kyphosis patients) over an 8-year period were investigated via postoperative CT scans. Patients were divided into 3 groups (group I = 1998–1999, group II = 2001–2002, and group III = 2005). All pedicle screws were inserted via the free-hand technique using anatomic landmarks, specific entry sites, neurophysiologic, and radiographic confirmation. Pedicle screw position on CT scan was graded as acceptable versus violated, defined as the screw axis being outside the pedicle wall. Results. One hundred seven of 1023 pedicle screws (10.5%) demonstrated significant mediolateral pedicle wall violations (19 medial vs. 88 lateral, P = 0.001). groups I and III had significantly higher lateral wall violations than group II (P < 0.05) as did the kyphotic spines (vs. scoliotic spine, P < 0.05). There were significantly more screws placed in the periapical region over time (P < 0.0001), with left-sided lateral violations (T5–T8) increasing from group II to group III, while the number of medial violations significantly decreased with time (P < 0.0001). Pedicle screws placed on the right side showed a significant decrease in accuracy from group II to group III (P = 0.03). The average transverse angle of the acceptable screws was 15.3° which was significantly different from the medial (23.0°, P < 0.001) and lateral (10.6°, P < 0.001) violations between group I and group II. No screws demonstrated neurologic, vascular, or visceral complications. Conclusion. Overall accuracy of acceptable screws using the free-hand pedicle screw placement technique in the deformed spine was 89.5%, without any neurologic, vascular, or visceral complications over an 8-year period. The rate of medial violations decreased with time, as the number of screws placed in the periapical region increased.