Christopher R. Good

Revision rates following primary adult spinal deformity surgery: six hundred forty-three consecutive patients followed-up to twenty-two years postoperative.

Study Design. Retrospective study. Objective. To analyze the prevalence of and reasons for unanticipated revision surgery in an adult spinal deformity population treated at one institution. Summary of Background Data. No recent studies exist that analyze the rate or reason for unanticipated revision surgery for adult spinal deformity patients over a long period. Methods. All patients presenting for primary instrumented spinal fusion with a diagnosis of adult deformity at a single institution from 1985 to 2008 were reviewed using a prospectively acquired database. All surgical patients with instrumented fusion of ≥5 levels using hooks, hybrid, or screw-only constructs were identified. Patient charts and radiographs were reviewed to provide information as to the indication for initial and any subsequent reoperation. A total of 643 patients underwent primary instrumented fusion for a diagnosis of adult idiopathic scoliosis (n = 432), de novo degenerative scoliosis (n = 104), adult kyphotic disease (n = 63), or neuromuscular scoliosis (n = 45). The mean age was 37.9 years (range, 18–84). Mean follow-up for the entire cohort was 4.7 years, and 8.2 years for the subset of the cohort requiring reoperation (range, 1 month–22.3 years). Results. A total of 58 of 643 patients (9.0%) underwent at least one revision surgery and 15 of 643 (2.3%) had more than one revision (mean 1.3; range, 1–3). The mean time to the first revision was 4.0 years (range, 1 week–19.7 years). The most common reasons for revision were pseudarthrosis (24/643 = 3.7%; 24/58 = 41.4%), curve progression (13/643 = 2.0%; 13/58 = 20.7%), infection (9/643 = 1.4%; 9/58 = 15.5%), and painful/prominent implants (4/643 = 0.6%; 4/58 = 6.9%). Uncommon reasons consisted of adjacent segment degeneration (3), implant failure (3), neurologic deficit (1), and coronal imbalance (1). Revision rates over the follow-up period were: 0 to 2 years (26/58 = 44.8%), 2 to 5 years (17/58 = 29.3%), 5 to 10 years (7/58 = 12.1%), >10 years (8/58 = 13.8%). Conclusion. Repeat surgical intervention following definitive spinal instrumented fusion for primary adult deformity performed at a single institution demonstrated a relatively low rate of 9.0%. The most common reasons for revision were predictable and included pseudarthrosis, proximal or distal curve progression, and infection.

Can Posterior-Only Surgery Provide Similar Radiographic and Clinical Results as Combined Anterior (Thoracotomy/Thoracoabdominal)/Posterior Approaches for Adult Scoliosis?

Study Design. Retrospective matched cohort analysis. Objective. To determine if posterior-only (post-only) surgical techniques consisting of pedicle screws, osteotomies, transforaminal lumbar interbody fusion, and bone morphogenetic protein-2 may provide similar results as compared anterior (thoracotomy/thoracoabdominal)/posterior surgical approaches for the treatment of adult spinal deformity with respect to correction, fusion rates, or outcomes. Summary of Background Data. Combined anterior/posterior (A/P) fusion has traditionally been used to treat many adult scoliosis deformities. Anterior approaches negatively impact pulmonary function and require additional operative time and anesthesia. Methods. Twenty-four patients who had A/P fusion for primary adult scoliosis (16 staged, 8 same-day) were matched with a cohort of 24 patients who had post-only treatment. Anterior fusion was performed via a thoracotomy (n = 1)/thoracoabdominal (n = 23) approach. All post-only surgeries were under one anesthesia. Minimum 2-year follow-up included radiographic, clinical, and outcomes data. Results. There were no significant differences between groups for age, gender, diagnosis, comorbidities, preoperative curve magnitudes, or global balance. Postoperative radiographic correction and alignment were similar for both groups except for thoracolumbar curve percent improvement which was statistically better in the post-only group (P = 0.03). The average surgical time was higher in A/P versus post-only group (11.6 vs. 6.9 hours, P < 0.0001) as was total estimated blood loss (1330 vs. 980 mL, P = 0.04). Hospital length of stay (LOS) was longer in A/P versus post-only group (11.9 vs. 8.3 days, P = 0.03). There were no significant differences between postoperative complications. Revision surgery was performed in 5 A/P and 2 post-only patients. Higher pseudarthrosis rates found in the A/P versus post-only (17 vs. 0%) were not significant (P = 0.11). SRS-30 and Oswestry scores reflected a similar patient assessment before surgery, and improvement between groups at follow-up. Conclusion. Post-only adult scoliosis surgery achieved similar correction to A/P surgery while decreasing blood loss, operative time, length of stay, and avoiding additional anesthesia. Complications, radiographic, and clinical outcomes were similar at over 2-year follow-up.

Risk Factors and Outcomes for Catastrophic Failures at the Top of Long Pedicle Screw Constructs: A Matched Cohort Analysis Performed at a Single Center

Study Design. Retrospective review with matched-cohort analysis performed at a single institution. Objective. To determine risk factors and outcomes for acute fractures at the proximal aspect of long pedicle screw constructs. Summary of Background Data. Acute fractures at the top of long segmental pedicle screw constructs (FPSC) can be catastrophic. Substantial surgical increase in lordosis may precipitate this problem. In relation to a matched cohort, we postulated that age, body mass index (BMI), and significant correction of lumbar lordosis would increase risk of FPSC and patients with FPSC would have lesser improvements in outcomes. Methods. Thirteen patients who sustained FPSC between 2000 and 2007 were evaluated. During this time, 264 patients aged 40 or older had a spinal fusion from the thoracic spine to the sacrum using an all-pedicle screw construct. A cohort of 31 of these patients without FPSC but with all pedicle screw constructs was matched for diagnosis of positive sagittal imbalance, gender, preoperative C7 sagittal plumb, and number of levels fused. Results. There was a significant difference in age (P = 0.02) and BMI (P = 0.006) between the matched groups. There was no significant difference in preoperative/postoperative C7 plumb or change in lumbar lordosis between groups. Acute neurological deficit developed in 2 patients; both patients improved substantially after revision surgery. Nine patients underwent proximal extension of the fusion. For 7 of the 13 FPSC patients with bone mineral density data (BMD) available, average T score was−1.73; −0.58 for the matched group (10/31 with bone mineral density data) (P = 0.02). Conclusion. Factors that increased the risk of FPSC included obesity and older age. Osteopenia increased the risk as evidenced by BMD (based on 17 patients) and the older age of these patients. There was no statistical difference in clinical improvement between groups based on ODI, but the FPSC group did demonstrate a smaller improvement in ODI score than the matched cohort.

Epidural Spinal Cord Compression With Neurologic Deficit Associated With Intrapedicular Application of Hemostatic Gelatin Matrix During Pedicle Screw Insertion

Study Design. Case report. Objective. In order to demonstrate the dangers of intrapedicular application of a hemostatic gelatin matrix to decrease blood loss during pedicle screw insertion, we present 2 patients who—as a result of inadvertent extravasation of the matrix into the spinal canal—developed epidural spinal cord compression (ESCC) requiring emergent decompression. Summary of Background Data. Variety of hemostatic agents can control bleeding during pedicle screw insertion. We have often used a hemostatic gelatin matrix to decrease bleeding from cannulated pedicles by injecting the material into the pedicle after manually palpating the pedicle. Methods. Medical records and radiographic studies of 2 patients with AIS who underwent surgical treatment of their deformity and developed a neurologic deficit due to extravasation of FloSeal were reviewed. Results. A 15 year-old male underwent T4 to L2 posterior spinal fusion (PSF). During pedicle screw insertion, a change in NMEPs and SSEPs was noted. A wake-up test confirmed bilateral LE paraplegia. Screws were removed and no perforations were noted on manual palpation. MRI showed T7 to T10 ESCC. He underwent a T5 to T10 laminectomy and hemostatic gelatin matrix noted in the canal and was evacuated. He was ambulatory at 2 weeks and by 3 months he had complete recovery. The second patient was a 15 year-old female who underwent T4 to L1 PSF. Following screw insertion, deterioration in NMEPs and SSEPs was noted. Screws were removed and SCM data returned to baseline. Except for 3 screws that had an inferior breach (Left T7 and Bilateral T8), screws were reinserted and remainder of the surgery was uneventful. Postoperative examination was normal initially but 2 days later, she developed left LE numbness/weakness. Implants were removed and MRI showed T4 to T9 ESCC.She underwent a left (concave) T4 to T9 hemilaminectomy. Hemostatic gelatin matrix was noted and was evacuated. Six weeks following surgery, she had a complete neurologic recovery. Conclusions. The use of a hemostatic gelatin matrix to decrease bleeding from cannulated pedicles during pedicle screw insertion can result in inadvertent extravasation into the spinal canal resulting in ESCC even in the absence of an apparent medial pedicle breach. Given the dangers associated with the technique, we recommend that gelatin matrix products be used judiciously during pedicle screw insertion.

Spinal fusion for spastic neuromuscular scoliosis: is anterior releasing necessary when intraoperative halo-femoral traction is used?

Study Design. Retrospective radiographic and clinical study. Objective. To compare the complications and radiographic outcomes of 2 types of surgical treatments, posterior-only fusion and circumferential fusion, in patients with nonambulatory quadriplegic cerebral palsy treated with adjunctive intraoperative halo-femoral traction. Summary of Background Data. Circumferential anterior-posterior spinal fusion (A/PSF) has been used to improve deformity correction and rate of fusion in patients with neuromuscular scoliosis (NMS) but is associated with increased morbidity. Anterior procedures may increase operative time (OR time) and estimated blood loss (EBL) as well as compromise pulmonary function. Posterior-only spinal fusion (PSF-only) may be sufficient, thereby forgoing the need for the anterior approach without sacrificing deformity correction or outcome. Methods. Twenty-six patients (age <21 years) who underwent PSF-only for spastic NMS (quadriplegic cerebral palsy) were matched with a comparison cohort of 26 patients who underwent A/PSF (11 staged, 15 same day). All posterior fusions extended from the proximal thoracic spine (T2/T3) to the pelvis. Anterior fusions used a thoracoabdominal approach. All 52 patients underwent intraoperative halo-femoral traction. Mean follow-up for PSF-only was 2.9 years and A/PSF 3.3 years. Results. There were no significant differences between the 2 groups in demographic data or preoperative radiographic measures. The PSF-only group had statistically significant shorter OR time (6.1 vs. 10.3 hours), lower EBL (873 vs. 1361 mL), lower frequency of postoperative intubation (38% vs. 81%), shorter length of postoperative intubation (2 vs. 6.5 days), and lower frequency of postoperative pulmonary complications (7.7% vs. 26.9%). There were no statistically significant differences at the final follow-up for thoracolumbar/lumbar curve Cobb, % correction of thoracolumbar/lumbar Cobb, pelvic obliquity, C7 plumb line and the center sacral vertical line, sagittal T5–T12, sagittal T10–L2, and sagittal T12–S1 Cobb measurements. There were no halo-femoral traction-related complications. Conclusions. When intraoperative halo-femoral traction is used, PSF-only surgery for NMS can provide excellent curve correction and spinal balance. In this study, the PSF-only group had shorter OR time, lower EBL, lower frequency of postoperative intubation, and fewer cases of pneumonias when compared with A/PSF with similar radiographic outcomes at 2-year follow-up.