Prokopis Annis

Early proximal junctional failure in patients with preoperative sagittal imbalance.

BACKGROUND CONTEXT Proximal junctional failure (PJF) is a recognized complication of spinal deformity surgery. Acute PJF (APJF) has recently been demonstrated to be 5.6% in the adult spinal deformity (ASD) population. The incidence and rate of return to the operating room for APJF have not been specifically investigated in individuals with sagittal imbalance. PURPOSE The purpose of this study was to report the incidence of APJF in patients with preoperative sagittal imbalance and the rate of return to the operating room for APJF. STUDY DESIGN/SETTING This study is based on a retrospective review of prospectively collected database of ASD patients. PATIENT SAMPLE One hundred seventy-three consecutive patients were included with preoperative sagittal imbalance according to one of the following common parameters: sagittal vertical axis (SVA) greater than 50 mm, global sagittal alignment greater than 45°, or pelvic incidence minus lumbar lordosis greater than 10°. OUTCOME MEASURES Outcome measure was presence and/or absence of APJF defined as fracture at the upper instrumented vertebra (UIV) or UIV+1, failure of UIV fixation, 15° or more proximal junctional kyphosis, or need for extension of instrumentation within 6 months of surgery. METHODS We performed radiographic measurements on X-rays at preoperative, immediate postoperative, and 6-month follow-up visits. The APJF rate was reported for the entire patient population with preoperative sagittal imbalance. Acute PJF incidence was calculated postoperatively for each of the accepted sagittal balance parameters and/or formulas. Patients with persistent postoperative sagittal imbalance were compared with the sagittally balanced group. We also assessed for threshold values. RESULTS Acute PJF was observed in 60 of 173 patients (35%) and was least common in fusions with the UIV in the upper thoracic (UT) spine (p=.035). Of those who developed APJF, 21.7% required surgery. Proximal junctional kyphosis 15° or more was the most common form of APJF in fusions to the UT spine but least likely to need revision (p=.014). The most common mode of failure in lower thoracic (LT) or lumbar (L) fusions was UIV fracture. Postoperative SVA less than 50 mm was a significant risk factor for APJF (p=.009). CONCLUSIONS Acute PJF is more common in patients with preoperative sagittal imbalance (35%) than the general adult deformity patient population, and 37% of those with APJF require revision. It is least common when the UIV is in the UT spine, compared with the LT or L spine. Sagittal balance correction to an SVA 50 mm or less was a significant risk factor in patients with preoperative sagittal imbalance.

Predictive Factors for Acute Proximal Junctional Failure after Adult Deformity Surgery with Upper Instrumented Vertebrae in the Thoracolumbar Spine

Study Type Retrospective cohort study. Introduction Acute proximal junctional failure (APJF) was recently defined by the International Spine Study Group as: postoperative fracture of the upper instrumented vertebrae (UIV) or UIV + 1; UIV implant failure; proximal junctional kyphosis (PJK) increase > 15 degrees; or need for proximal extension of the fusion within 6 months of surgery.1 The incidence and revision rates of APJF have been reported to be higher when the UIV is located in the lower thoracolumbar (TL) spine mostly because of high incidence of UIV or UIV + 1 fractures.2 Sagittal deformity overcorrection has been considered as a potential risk factor.3 4 Objective The purpose of this study is to assess independent predictive factors and timing for revisions of APJF in adult deformity patients with UIV in the TL (T9–L2) spine. Methods Retrospective review of 135 consecutive patients with minimum 2-year follow-up, treated at a single institution for adult spinal deformity, all with UIV in the TL spine (T9–L2). Fusions were divided into three cohorts based on the UIV location (T9–T10 vs. T11–T12 vs. L1–L2). Demographic data were reviewed and radiographic parameters were measured preoperatively, immediately postoperatively, at 6 months and at the final follow-up. Incidence and failure modes of APJF, as well as timing for APJF revision are reported. Risk factors for APJF were assessed with univariate and multivariate regression analysis models. Results A total of 135 consecutive patients were reviewed, with mean follow-up 42 months (24–126). Mean age was 66 years (24–86). There were no differences in the preoperative radiographic parameters between patients in any of the three cohorts with APJF. The incidence of APJF was 38.5%, with a trend toward higher APJF in the T9–T10 group (p = 0.07) (Table 1). When UIV was at T10, the incidence of APJF was 57.1%, significantly higher than the adjacent vertebrae, T9 and T11 (p = 0.03 and p = 0.01, respectively). The overall revision rate for APJF was 17%, most often for UIV fracture, while PJK > 15 degrees alone had the highest 2 and 5 years survival (100%) (Fig. 1). Univariate analysis revealed preoperative sagittal vertical axis > 5 cm, postoperative PJA > 5 degrees and thoracic kyphosis > 30 degrees, and instrumentation to the pelvis as risk factors for APJF (Table 2). Multivariate regression analysis confirmed postoperative PJA > 5 degrees, and greater correction of lumbar lordosis (LL) as independent risk factors for APJF (Table 3). Conclusion The incidence of APJF in adult deformity patients is high if the UIV is in the lower thoracic or lumbar spine, with a trend toward higher rates when the UIV is at T10. Fracture at the UIV lead to the highest revision rate, while PJK > 15 degrees without fracture or hardware failure had the longest revision-free survival. Postoperative PJA > 5 degrees and greater correction of LL are independent risk factors for APJF.

Reoperation and revision rates of 3 surgical treatment methods for lumbar stenosis associated with degenerative scoliosis and spondylolisthesis.

Study Design. Retrospective cohort analysis. Objective. To compare early treatment failures, survivorship, and clinical outcomes of 3 procedures used to treat symptomatic lumbar spinal stenosis and degenerative deformity. Summary of Background Data. Symptomatic lumbar stenosis is commonly seen in association with degenerative deformity, often leading to more complex surgical treatment, with laminectomy and fusion, supplanting laminectomy alone. More recently, the interspinous process spacer (ISP), developed to treat straightforward spinal stenosis, has been used in patients with spinal deformity to limit morbidity, although no studies have compared outcomes in this patient population. Methods. A retrospective cohort analysis of 90 consecutive patients, mean age 70 years, with 5-year mean follow-up (minimum, 2 yr), treated for stenosis with associated deformity with ISP device placement, laminectomy alone, or laminectomy and short-segment fusion. Early failure was defined as return to the operating room for revision of the index level or adjacent segment within 2 years. A Kaplan-Meier survival analysis was performed, and clinical outcomes and patient satisfaction was assessed. Results. Reoperation within 2 years was noted in 16.7% of patients treated for spinal stenosis and mild deformity. There was a significantly higher rate of same-level recurrence in the ISP group (33.3%), than the laminectomy (8.3%) and lami/fusion groups (0%) (P< 0.0001). Early reoperation due to adjacent segment pathology (ASP) was most common in the lami/fusion group (13.3%). Kaplan-Meier analysis revealed lowest survival for the ISP group and highest survival in the laminectomy-alone group at 2 years (P= 0.043) and 5 years (P= 0.007). Conclusion. Early failure was significantly more common in patients treated with an ISP device for spinal stenosis and lumbar deformity, whereas reoperation due to symptomatic adjacent segment pathology was most common in patients treated with laminectomy and fusion. Laminectomy alone had the highest rate of survival. Level of Evidence: 3

Scoliosis research society-22 results in 3052 healthy adolescents aged 10 to 19 years.

Study Design. Cross-sectional survey. Objective. The purpose of our study was to evaluate a large population of adolescents from a broad mix of racial/ethnic backgrounds and age groups to better establish baseline normative values for the Scoliosis Research Society-22 (SRS-22). Summary of Background Data. The SRS-22 instrument was developed to assess treatment outcomes in patients with adolescent idiopathic scoliosis. To accurately assess real changes in outcome measures, the SRS-22 must be able to differentiate patients with and without adolescent idiopathic scoliosis. Methods. The SRS-22 was administered to 3052 healthy adolescents, 51% female and 49% male, with a mean age of 14.6 years (range, 10–19 yr). We grouped the children into 3 age groups for analysis: 10 to 12 years (362), 13 to 15 years (1487), and 16 to 19 years (1203). Racial/ethnic groups included: Caucasian, 62%; African American, 14%; Hispanic, 9%; Asian, 6%; Native American, 5%; and Pacific Islander, 4%. SRS-22 scores were analyzed to establish normative values for each group. Results. Mean SRS-22 scores were: activity, (4.31 ± 0.54); pain, (4.44 ± 0.67); image, (4.41 ± 0.64); mental, (3.96 ± 0.81); and total, (4.26 ± 0.54). Females had lower scores in the mental domain (3.90) than males (4.04) (P < 0.001). The scores of children aged 10 through 12 years were higher in the domains of activity (P = 0.000), pain (P < 0.001), and mental (P < 0.001) than those of children aged 13 through 15 years and 16 through 19 years. The 13- to 15-year group had significantly higher scores than the 16- to 19-year group (P < 0.001) in each of the same categories. Regarding race/ethnicity, Caucasians tended to report higher scores in most domains than other race/ethnic groups. Hispanics scored lower in all domains than the non-Hispanic group. Conclusion. Age, sex, and race had a significant impact on SRS-22 scores in a large group of healthy adolescents. In general, scores lowered as age increased from 10 to 19 years, Caucasians scored higher in function, pain, and image than other racial groups, and Hispanics scored lower than non-Hispanics in all domains. These factors should be considered when evaluating SRS-22 scores. Level of Evidence: 3

The fate of L5-S1 with low dose BMP-2 and pelvic fixation, with or without interbody fusion, in adult deformity surgery

Study Design. Retrospective comparative case series. Objective. Evaluate L5–S1 fusion rates when lower dose of bone morphogenic protein-2 (BMP-2) (average 3.2 mg) and pelvic fixation were used, with or without interbody fusion. Summary of Background Data. Pseudarthrosis at L5–S1 is one of the most common complications of long fusions to the sacrum in adult deformity surgery. Strategies for decreasing pseudarthrosis include interbody fusion, use of BMP-2 at the lumbosacral junction, and the use of sacropelvic fixation, individually or in combination. High-dose BMP-2 (20–40 mg) placed posterolaterally has shown comparable fusion rates with interbody fusion. Methods. Retrospective review of 61 consecutive patients with minimum 2-year follow-up at a single institution. All patients had an isolated posterior approach, 5 or more levels fused including L5–S1, use of pelvic fixation, and no prior L5–S1 procedures. The patients were divided in 2 groups for comparison on the basis of the use of an interbody cage/fusion at the L5–S1 level. Revision rates and implant-related complications were also reported. Results. The fusion rate at L5–S1 was 97% (59/61), with no difference between the interbody and no interbody fusion groups (97% vs. 96%, P = 1.0). There were no significant differences in the radiographical parameters or deformity correction between the groups. The mean amount of BMP-2 used in the interbody group was 4.1 mg (2–10), 2.5 mg (0–8) in the disc space, and 1.6 mg (0-4) in the interbody cage, whereas there was no difference in the amount of recombinant human bone morphogenic protein-2 placed posterolaterally between the 2 groups (interbody fusion = 1.6 vs. non–interbody fusion = 2.0 mg, P = 0.08) along with autograft and allograft. The overall revision rate for L5–S1 nonunion was 1.6%. Conclusion. The use of low dose of BMP-2 at the L5–S1 level in combination with sacropelvic fixation achieved satisfactory fusion rates in adult deformity surgery. No additional benefit was encountered by adding an interbody cage. Level of Evidence: 4

Neuroforaminal chondrocyte metaplasia and clustering associated with recombinant bone morphogenetic protein-2 usage in transforaminal lumbar interbody fusion

BACKGROUND CONTEXT Recombinant human bone morphogenetic protein-2 (rhBMP-2) is commonly used to augment posterior and interbody spinal fusion techniques and has many reported side effects. Neuroforaminal heterotopic ossification (HO) is a known cause of postoperative leg pain, but the pathohistologic composition of this material is not well understood. PURPOSE The purpose of this article was to report the histologic composition of a case of HO and lumbar radiculopathy after transforaminal lumbar interbody fusion with rhBMP-2. STUDY DESIGN/SETTING This is a case report. PATIENT SAMPLE This is a single patient case report. OUTCOME MEASURES The outcomes considered were physician-recorded clinical, physiological, and functional measures. METHODS A retrospective review of a single patient was performed. Clinical, radiographic, and pathologic specimens were reviewed and are reported. RESULTS A 69-year-old woman presented with low back pain and right leg radicular pain associated with L4-L5 stenosis and a recurrent facet cyst. After attempted nonsurgical care, she underwent an L4-L5 revision decompression with interbody and posterolateral fusions including off-label rhBMP-2. Postoperatively, her symptoms resolved for approximately 7 months but then returned in association with right L4-L5 foraminal HO. The ectopic tissue was notably larger than suggested by preoperative computed tomographic scan. It was decompressed, which then improved her symptoms. Histologic examination of the specimen revealed three discrete tissue types: a nonspecific fibrovascular stroma; immature osteoid and woven bone; and chondrocyte metaplasia with chondrocyte clustering. CONCLUSIONS Neuroforaminal HO formation is a reported side effect associated with the off-label use of rhBMP-2 for posterior lumbar interbody fusion. The mechanism of formation and the composition of this material are not well understood but may involve a chondrocyte differentiation pathway.

Perioperative Complications of Pedicle Subtraction Osteotomy

Study Design Retrospective case series. Objective To describe the perioperative complications (0 to 90 days) associated with pedicle subtraction osteotomies (PSOs) performed at a tertiary spine center by two experienced spine surgeons who recently adopted the technique. Methods We reviewed all 65 patients (47 women and 18 men; mean age 60 years, range 24 to 80) who underwent a PSO at our institution. Descriptive data and analysis of complications were limited to the perioperative time (within 90 days of surgery). Data analyzed included operative time, length of stay (LOS), estimated blood loss (EBL), blood products, comorbidities, neurologic complications, and medical complications. Complications were rated as major and minor. Radiographic data was also analyzed. Results Ten patients (15.4%) had a major complication, and 15 (23%) had a minor complication. There were three perioperative deaths. The most common major complication was neurologic deficit (6.2%, 4/65), three with a permanent foot drop, and one with paraplegia secondary to postoperative hematoma. There were no differences between patients with and without a major complication in regard to age, gender, comorbidities, operative time, number of levels fused, and EBL (p > 0.05). Patients with a major complication had a longer intensive care unit stay (p = 0.04). There was no difference in the rate of major complications between the initial and later cases performed. Conclusion The major complication rate for pedicle subtraction osteotomy was 15% and the minor complication rate was 23%. The most common major complication was neurologic deficit in 6.2%. The complication rate did not change with increased surgeon experience.

Cervical Spondylotic Myelopathy (CSM)

Cervical spondylotic myelopathy (CSM) is the clinical manifestation of compression of the spinal cord caused by degenerative changes of the cervical spine. It is a rare but potentially devastating manifestation of cervical spondylosis that usually has a chronic and slowly progressive character. While rare, it is reported as the most common disorder causing dysfunction of the spinal cord in the USA.