Radiographic Proximal Junctional Kyphosis Research Articles

Revision Strategy for Proximal Junctional Failure: Combined Effect of Proximal Extension and Focal Correction.

Retrospective review of a prospectively-collected multicenter database. The objective of this study was to determine optimal strategies in terms of focal angular correction and length of proximal extension during revision for PJF. 134 patients requiring proximal extension for PJF were analyzed in this study. The correlation between amount of proximal junctional angle (PJA) reduction and recurrence of proximal junctional kyphosis (PJK) and/or PJF was investigated. Following stratification by the degree of PJK correction and the numbers of levels extended proximally, rates of radiographic PJK (PJA >28° & ΔPJA >22°), and recurrent surgery for PJF were reported. Before revision, mean PJA was 27.6° ± 14.6°. Mean number of levels extended was 6.0 ± 3.3. Average PJA reduction was 18.8° ± 18.9°. A correlation between the degree of PJA reduction and rate of recurrent PJK was observed (r = -.222). Recurrent radiographic PJK (0%) and clinical PJF (4.5%) were rare in patients undergoing extension ≥8 levels, regardless of angular correction. Patients with small reductions (<5°) and small extensions (<4 levels) experienced moderate rates of recurrent PJK (19.1%) and PJF (9.5%). Patients with large reductions (>30°) and extensions <8 levels had the highest rate of recurrent PJK (31.8%) and PJF (16.0%). While the degree of focal PJK correction must be determined by the treating surgeon based upon clinical goals, recurrent PJK may be minimized by limiting reduction to <30°. If larger PJA correction is required, more extensive proximal fusion constructs may mitigate recurrent PJK/PJF rates.

Percutaneous Vertebroplasty and Upper Instrumented Vertebra Cement Augmentation Reducing Early Proximal Junctional Kyphosis and Failure Rate in Adult Spinal Deformity: Case Series and Literature Review.

One of the risks involved after long-segment fusions includes proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). There are reported modalities to help prevent this, including 2-level prophylactic vertebroplasty. In this study, our goal was to report the largest series of prophylactic cement augmentation with upper instrumented vertebra (UIV) + 1 vertebroplasty and a literature review. We retrospectively reviewed our long-segment fusions for adult spinal deformity from 2018 to 2022. The primary outcome measures included the incidence of PJK and PJF. Secondary outcomes included preoperative and postoperative Oswestry Disability Index, visual analog scale back and leg scores, surgical site infection, and plastic surgery closure assistance. In addition, we performed a literature review searching PubMed with a combination of the following words: "cement augmentation," "UIV + 1 vertebroplasty," "adjacent segment disease," and "prophylactic vertebroplasty." We found a total of 8 articles including 4 retrospective reviews, 2 prospective reviews, and 2 systematic reviews. The largest cohort of these articles included 39 patients with a PJK/PJF incidence of 28%/5%. Overall, we found 72 long-segment thoracolumbar fusion cases with prophylactic UIV cement augmentation with UIV + 1 vertebroplasty. The mean follow-up time was 17.25 months. Of these cases, 8 (11.1%) developed radiographic PJK and 3 (4.2%) required reoperation for PJF. Of the remaining 5 patients with radiographic PJK, 3 were clinically asymptomatic and treated conservatively and 2 had distal fractured rods that required only rod replacement. In this study, we report the largest series of patients with prophylactic percutaneous vertebroplasty and UIV cement augmentation with a low PJK and PJF incidence of 11.1% and 4.2%, respectively, compared with previously reported literature. Surgeons who regularly perform long-segment fusions for adult spinal deformity can consider this in their armamentarium when using methods to prevent adjacent segment disease because it is an effective modality in reducing early PJK and PJF that can often result in revision surgery.

Mechanical complications and patient-reported outcome measures associated with high pelvic incidence and persistent pelvic retroversion: the Roussouly "false type 2" profile.

The objective of this paper was to report mechanical complications and patient-reported outcome measures (PROMs) for adult spinal deformity (ASD) patients with a Roussouly "false type 2" (FT2) profile. ASD patients treated from 2004 to 2014 at a single center were identified. Inclusion criteria were pelvic incidence ≥ 60° and a minimum 2-year follow-up. FT2 was defined as a high postoperative pelvic tilt (PT), as defined by the Global Alignment and Proportion target, and thoracic kyphosis < 30°. Mechanical complications, defined as proximal junctional kyphosis (PJK) and/or instrumentation failure, were determined and compared. Scoliosis Research Society-22r (SRS-22r) scores were compared between groups. Ninety-five patients (normal PT [NPT] group 49, FT2 group 46) who met the inclusion criteria were identified and studied. Most surgeries were revisions (NPT group 30 [61%], FT2 group 30 [65%]), and most were performed via a posterior-only approach (86%) (mean ± SD 9.6 ± 5 levels). Proximal junctional angles increased after surgery in both groups, without differences between groups. Neither rates of radiographic PJK (p = 0.10), revision for PJK (p = 0.45), nor revision for pseudarthrosis (p = 0.66) were different between groups. There were no differences between groups for SRS-22r domain scores or subscores. In this single-center experience, patients with high pelvic incidence fixed with persistent lumbopelvic parameter mismatch and engaged compensatory mechanisms (Roussouly FT2) had mechanical complications and PROMs not different from those with normalized alignment parameters. Compensatory PT may be acceptable in some cases of ASD surgery.

Risk factors for proximal junctional kyphosis after pediatric spinal deformity surgery with halo gravity traction.

To determine risk factors for proximal junctional kyphosis (PJK) in pediatric patients with scoliosis undergoing halo gravity traction (HGT) prior to posterior spinal fusion (PSF). Data from consecutive patients who underwent PSF after HGT with 2-year follow-up were retrospectively collected from a single center. Patients were divided into two groups: PJK vs. no PJK. Twenty-five patients (age 13.6 ± 3.1years) underwent HGT for a mean of 42 ± 37days. Eight patients (32%) developed radiographic PJK and 1 (4%) developed proximal junctional failure. PJK patients had greater loss of cervical lordosis (-17.4 ± 23.2 vs. 2.7 ± 16.2°, p < 0.05), greater increase in lumbar lordosis (9.3 ± 19.5 vs. -2.8 ± 12.8°; p = 0.034) during traction, and smaller overall major coronal curve angle correction (-16.8 ± 30.6 vs. -36.6 ± 16.4°; p = 0.026). From postoperative to last follow-up, PJK patients had a greater increase in upper end vertebrae (UEV) slope (3.3 ± 7.8 vs. -4.0 ± 7.7°; p = 0.004). Selection of UIV based on which vertebra was most level either pre-traction or in-traction was not associated with PJK development (p > 0.05). In-traction radiographic changes of decreased cervical lordosis, decreased major coronal curve, increased lumbar lordosis, and disruption of cervical sagittal balance at last follow-up may have implications for level selection and risk of PJK.

Evolution of Proximal Junctional Kyphosis and Proximal Junctional Failure Rates Over 10 Years of Enrollment in a Prospective Multicenter Adult Spinal Deformity Database.

Retrospective cohort study. The aim of this study was to investigate the evolution of proximal junctional kyphosis (PJK) rate over 10-year enrollment period within a prospective database. PJK is a common complication following adult spinal deformity (ASD) surgery and has been intensively studied over the last decade. Patients with instrumentation extended to the pelvis and minimum 2-year follow-up were included. To investigate evolution of PJK/proximal junctional failure (PJF) rate, a moving average of 321 patients was calculated across the enrollment period. Logistic regression was used to investigate the association between the date of surgery (DOS) and PJK and/or PJF. Comparison of PJK/PJF rates, demographics, and surgical strategies was performed between the first and second half of the cohort. A total of 641 patients met inclusion criteria (age: 64±10 years, 78.2% female, body mass index: 28.3±5.7). The overall rate of radiographic PJK at 2 years was 47.9%; 12.9% of the patients developed PJF, with 31.3% being revised within 2-year follow-up. Stratification by DOS produced two halves. Between these two periods, rate of PJK and PJF demonstrated nonsignificant decrease (50.3%-45.5%, P =0.22) and (15.0%-10.9%, P =0.12), respectively. Linear interpolation suggested a decrease of 1.2% PJK per year and 1.0% for PJF. Patients enrolled later in the study were older and more likely to be classified as pure sagittal deformity ( P <0.001). There was a significant reduction in the use of three-column osteotomies ( P <0.001), an increase in anterior longitudinal ligament release ( P <0.001), and an increase in the use of PJK prophylaxis (31.3% vs 55.1%). Logistical regression demonstrated no significant association between DOS and radiographic PJK ( P =0.19) or PJF ( P =0.39). Despite extensive research examining risk factors for PJK/PJF and increasing utilization of intraoperative PJK prophylaxis techniques, the rate of radiographic PJK and/or PJF did not significantly decrease across the 10-year enrollment period of this ASD database.

Risk Factors and Three Radiological Predictor Models for the Progression of Proximal Junctional Kyphosis in Adult Degenerative Scoliosis Following Posterior Corrective Surgery: 113 Cases With 2-years Minimum Follow-Up.

Retrospective cohort study. To identify risk factors and predictive models for proximal junctional kyphosis (PJK) in a long-term follow-up of patients with adult degenerative scoliosis (ADS) following posterior corrective surgeries. A consecutive 113 ADS patients undergoing posterior corrective surgery between January 2008 and April 2019 with minimum 2-year follow-up were included. All patients underwent preoperative, postoperative, and final follow-up by X-ray imaging. Multivariate logistic analysis was performed on various risk factors and radiological predictor models. PJK was identified radiographically in 46.9% of patients. Potential risk factors for PJK included postoperative thoracic kyphosis (TK) (P < .05), final follow-up Pelvic Tilt (PT) (P < .05), PT changes at final follow-up (P < .05), age over 55 years old at the surgery (P < .05), theoretical thoracic kyphosis-actual thoracic kyphosis mismatch (TK mismatch) (P < .05) and theoretical lumbar lordosis-acutal lumbar lordosis mismatch (LL mismatch) (P < .05). As for the predictive models, PJK was predictive by the following indicators: preoperative global sagittal alignment ≥45° (Model 1), postoperative pelvic incidence-lumbar lordosis mismatch (PI-LL)≤10° and postoperative PI-LL overcorrection (Model 2), and TK+LL≥0° (Model 3) (P < .05). Postoperative TK mismatch (OR = 1.064) was independent as risk factors for PJK, with the cut-off values respectively set at -28.56° to predict occurrence of PJK. The risk of radiographic PJK increases with an age over 55 years old and higher postoperative TK. In addition, postoperative TK mismatch is an independent risk factor for developing PJK. All three predictive models could effectively indicate the occurrence of PJK.

Postoperative and Intraoperative Cement Augmentation for Spinal Fusion

To review outcomes of patients undergoing spinal fusion with prophylactic cement augmentation (CA) of pedicle screws and adjacent levels. In a retrospective case-control study, 59 patients underwent CA of pedicle screws for spinal fusion between 2003 and 2018. Most patients (83%) underwent postoperative CA, while 17% underwent intraoperative CA. Outcomes of CA techniques were compared, and patients undergoing CA for a thoracolumbar fusion (n= 51) were compared with a cohort not undergoing CA (n= 39). Mean follow-up was 3 years. In patients receiving CA, survivorship free of proximal junctional kyphosis (PJK) was 94%, 60%, and 20% at 2, 5, and 10 years postoperatively. Survivorship free of revision was 95%, 83%, and 83% at 2, 5, and 10 years postoperatively. Development of PJK (P= 0.02, odds ratio [OR] 24.44) was associated with revision surgery. There were 4 (7%) cardiopulmonary complications. Patients who received CA for thoracolumbar fusion were older (70 years vs. 65 years) and were more likely to have osteoporosis (53% vs. 5%) than patients who did not receive CA. CA was associated with a decreased risk of PJK (P= 0.009, OR 0.16), while osteoporosis (P= 0.05, OR 4.10) and fusion length ≥8 levels (P= 0.06, OR 2.65) were associated with PJK. PJK was associated with revision surgery (P= 0.006, OR 12.65). CA allows for substantial rates of radiographic PJK; however, this typically does not result in a need for revision surgery and leads to revision and PJK rates that are comparable to patients undergoing long segment fusions without osteoporosis.

The impact of segmental spinal alignment on the development of proximal junctional kyphosis after instrumented posterior spinal fusions for idiopathic scoliosis.

To assess if the preservation of preoperative kyphosis within the cephalad two motion segments of instrumented posterior spinal fusions (PSF), for idiopathic scoliosis (IS), would be associated with lower frequency of proximal junctional kyphosis (PJK) at 2years postoperatively. Previous studies on PJK in IS have reported conflicting findings; none has evaluated the relationship between segmental kyphosis within the cephalad instrumented construct and PJK. One hundred consecutive patients undergoing PSF for IS by a single surgeon with minimum 2-year follow-up were evaluated. Radiographic evaluation focused on sagittal alignment of the upper instrumented vertebrae (UIV), the 1 and 2 vertebrae cephalad (UIV + 1, UIV + 2) and caudal (UIV - 1, UIV - 2). This was measured between the inferior endplate of the UIV and the superior endplate of the UIV + 1 and UIV + 2 or between the superior endplate of the UIV and the inferior endplate of the UIV - 1 and UIV - 2. PJK was defined as present if the final UIV + 2 ≥ 10° and final UIV + 2-preop UIV + 2 ≥ 10°. There were 78 females and 22 males whose mean age was 14.6 (± 2.1) years at surgery; mean follow-up was 3.9 (2-9.3) years. The overall frequency of PJK was 25% (25/100) at final follow-up. Preoperative mean coronal curve measured 63° (40°-107°) with a mean 66% correction at final follow-up. UIV was T2 (n = 15), T3 (n = 47) or T4 (n = 38). More caudal UIVs were associated with PJK development (p = 0.04): T2 (13%), T3 (21%) and T4 (34%). Greater preoperative T5-T12 thoracic kyphosis and UIV - 2, and lower major curve apex (below T12) were more likely to develop PJK (p = 0.019, p = 0.004 and p = 0.007, respectively). Post-operatively, larger values for UIV - 1 (p ≤ 0.001) and UIV - 2 (p = 0.002) were associated with PJK at final follow-up. Longer fusion lengths (10-13 vs. 6-9 segments, p = 0.02) and the presence of thoracolumbar/lumbar structural curves (Lenke 3-6 vs. 1-2, p = 0.032) had higher rates of PJK (32% vs 10% and 37% vs 18%, respectively). Changes in UIV - 1 and UIV - 2 (preoperatively to immediately post-op) did not influence the development of PJK. At final follow-up, no patient required revision surgery for symptomatic proximal junctional kyphosis. In this study, changes in UIV - 1 and UIV - 2 at surgery were not related to PJK. Greater preoperative T5-T12 thoracic kyphosis and UIV - 2, lower major curve apex (T12 and below), and greater post-operative UIV - 1 and UIV - 2 were associated with higher frequencies of PJK. Higher UIV (T2 vs. T4) and LIV levels had a protective effect against PJK. Based on this study, the preservation of segmental kyphosis within the instrumented cephalad two levels of the PSF did not minimize the occurrence of radiographic PJK. Level IV.

31. Evolution of proximal junctional kyphosis and proximal junctional failure rates over 10 years of enrollment in a prospective multicenter adult spinal deformity database

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) is one of the most common complications following adult spinal deformity (ASD) surgery and has been intensively studied over the last decade. <h3>PURPOSE</h3> This study aims to investigate the evolution of PJK rate over a 10-year enrollment period within a prospective database of ASD patients. The hypothesis is that the rate of PJK and PJF will decrease across time. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospective multicenter database. <h3>PATIENT SAMPLE</h3> A total of 641 ASD patients with minimum 2-year follow-up. <h3>OUTCOME MEASURES</h3> Rate of PJK and PJF. <h3>METHODS</h3> ASD patients with a fusion extended to pelvis and a minimum of 2-year follow-up were included. To investigate a continuous evolution of the PJK/PJF rate, a moving average of 321 patients was calculated across the entire enrollment period, allowing for 95% CI on rate for an incidence of 30% or less. Radiographic PJK was defined as a PJA>10° at 2Y and ΔPJA>10° between preoperative and 2-year follow-up. PJF was defined as either revised for PJK before 2-year visit or Severe radiographic PJK at 2-year follow-up (PJA>28° & ΔPJA>22°). Logistic regression was used to investigate association between date of surgery and PJK and/or PJF. Comparison of PJK rate, demographics and surgical strategies was performed between the first and second half of the cohort. <h3>RESULTS</h3> A total of 641 patients met inclusion criteria (age: 64±10yo, 78.4% F, BMI: 28.3±5.7). The overall rate of radiographic PJK at 2-year was 48.2% (N=309/641); 12.9% (N=83/641) of the patients developed a PJF, with 31.3% (N=26/83) being revised within 2-year. The stratification by date of surgery (DOS) yielded 2 timeframes: First=Oct 2008 to Jul 2014 (with a median DOS of Sep 2011), and Second=Jun 2014 to Apr 2018 (with a median DOS of Aug 2016). Between these 2 periods, the rate of radiographic PJK demonstrated a nonsignificant decrease from 50.3% to 45.5% (p=0.22) and PJF from 15.0% to 10.9% (p=0.12). Linear interpolation of the rate of PJK and PJF by enrollment using a moving average suggested a decrease of 1.1% PJK per year and 1.0% PJF per year. Over the study period, patients became continuously older (from 62.6±10.3 to 65.5±8.7 p<0.001) and were more likely be classified as a pure sagittal deformity (SRS Type N from 31.2% to 47.4% p<0.001). Across the enrollment period, there was a shift in surgical strategy, with a significant reduction of 3CO use (35.1% vs 20.8% p<0.001), an increase in ALL release (0% vs 18.4% p<0.001), a decrease in the number of levels fused (12.2±3.5 vs 11.7±3.9 p=0.016), and an increase in the use of PJK prophylaxis (31.3% vs 55.1%). Logistical regression analysis demonstrated no significant association between date of surgery and radiographic PJK (p=0.19) or PJF (p=0.39). <h3>CONCLUSIONS</h3> Despite extensive research examining risk factors for PJK/PJF and increasing utilization of intraoperative PJK prophylaxis techniques, the rate of radiographic PJK and/or PJF did not significantly decrease across the 10-year enrollment period of this ASD database. The increase in patient risk factors (older) was probably balanced by changes in surgical strategy and preoperative optimization. Continuous enrollment and follow-up will allow ongoing study which may eventually lead to significant decreases in the rate of PJK and PJF. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

The utility of supine radiographs in the assessment of thoracic flexibility and risk of proximal junctional kyphosis.

Supine radiographs have successfully been used for preoperative planning of lumbar deformity corrections. However, they have not been used to assess thoracic flexibility, which has recently garnered attention as a potential contributor to proximal junctional kyphosis (PJK). The purpose of this study was to compare supine to standing radiographs to assess thoracic flexibility and to determine whether thoracic flexibility is associated with PJK. A retrospective study was conducted of a single-institution database of patients with adult spinal deformity (ASD). Sagittal alignment parameters were compared between standing and supine and between pre- and postoperative radiographs. Thoracic flexibility was determined as the change between preoperative standing thoracic kyphosis (TK) and preoperative supine TK, and these changes were measured over the overall thoracic spine and the fused portion of the thoracic spine (i.e., TK fused). A case-control analysis was performed to compare thoracic flexibility between patients with PJK and those without (no PJK). The cohort was also stratified into three groups based on thoracic flexibility: kyphotic change (increased TK), lordotic change (decreased TK), and no change. The PJK rate was compared between the cohorts. A total of 101 patients (mean 63 years old, 82.2% female, mean BMI 27.4 kg/m2) were included. Preoperative Scoliosis Research Society-Schwab ASD classification showed moderate preoperative deformity (pelvic tilt 27.7% [score ++]; pelvic incidence-lumbar lordosis mismatch 44.6% [score ++]; sagittal vertical axis 42.6% [score ++]). Postoperatively, the average offset from age-adjusted alignment goals demonstrated slight overcorrection in the study sample (-8.5° ± 15.6° pelvic incidence-lumbar lordosis mismatch, -29.2 ± 53.1 mm sagittal vertical axis, -5.4 ± 10.8 pelvic tilt, and -7.6 ± 11.7 T1 pelvic angle). TK decreased between standing and supine radiographs and increased postoperatively (TK fused: -25.3° vs -19.6° vs -29.9°; all p < 0.001). The overall rate of radiographic PJK was 23.8%. Comparisons between PJK and no PJK demonstrated that offsets from age-adjusted alignment goals were similar (p > 0.05 for all). There was a significant difference in the PJK rate when stratified by thoracic flexibility cohorts (kyphotic: 0.0% vs no change: 18.4% vs lordotic: 35.0%; p = 0.049). Logistic regression revealed thoracic flexibility (p = 0.045) as the only independent correlate of PJK. Half of patients with ASD experienced significant changes in TK during supine positioning, a quality that may influence surgical strategy. Increased thoracic flexibility is associated with PJK, possibly secondary to fusing the patient's spine in a flattened position intraoperatively.

Proximal Fixation in Adolescent Scoliosis Lenke 1 and 3 Treated by Posteromedial Translation Using Sublaminar Bands: Transverse-pedicular Hook Claw Versus Transverse Hook-pedicular Screw Claw.

This is retrospective comparative study. Numerous studies have focused on the efficacy, safety, and restoration of thoracic kyphosis in adolescent idiopathic scoliosis surgery using posteromedial translation method with sublaminar bands and hook claws at the top. The relevance of exchanging the penultimate anchor, that is, the pedicle hook with a pedicle screw in a hybrid construction has not yet been assessed. Our objective was to assess, in adolescent scoliosis Lenke 1 and 3 operated by posteromedial translation using sublaminar bands, the proximal fixation claw influence (transverse-pedicular hook vs. transverse hook-pedicular screw) for postoperative correction and the proximal junctional kyphosis (PJK) at 2 years follow-up. A comparative monocentric retrospective study included adolescent idiopathic scoliosis thoracic requiring surgery, between 2015 and 2017, with 2 years follow-up. Clinical (complications, revision surgery, and scoliosis research society-30) and radiographic (coronal and sagittal parameters) assessment were reported. Radiologic PJK was defined by a proximal junctional angle increase of 10 degrees or more between postoperative period and the last follow-up. Sixty patients (age at surgery=16±2 y; mean Cobb angle=58.2±12 degrees) were divided into 2 similar groups according to upper fixation: transverse-pedicular hook (H-H) and transverse hook-pedicle screw (S-H). No statistical differences were found for correction parameters (P>0.05). We reported 2 cases of PJK in H-H group (N=2/30=6.6%) and none in S-H group (N=0/30) (P=0.1) none requiring revision. No infectious or neurological events were reported. Mean scoliosis research society-30 was 126±12.7 in H-H group whereas 129.3±10 in S-H group (P=0.4). No differences in postoperative correction and clinical results at 2 years follow-up were found. A claw with transverse-pedicular hook increase proximal junctional angle without significant increase on radiographic PJK incidence compared with a claw with transverse hook and pedicle screws.

State of the art: proximal junctional kyphosis-diagnosis, management and prevention.

Proximal junctional kyphosis (PJK) is a common problem that may occur following the surgical treatment of adult patients with spinal deformity. It is defined as the proximal junctional sagittal angle from the UIV and UVI + 2 of at least 10° AND at least 10° greater than the preop measurement. The reported incidence of radiographic PJK in the literature varies between 17 and 46%. A smaller subset of these patients may need revision surgery and are defined as proximal junctional failure (PJF), which can be associated with vertebral fracture, vertebral subluxation, failure of instrumentation, and neurological deficits. Several risk factors for development of PJK have been proposed. However, large-scale prospective studies are needed to better identify strategies to reduce the incidence of PJK.

Sagittal spinopelvic changes after posterior spinal fusion in adolescent idiopathic scoliosis.

PurposeThis article examines if longer posterior spinal fusions with instrumentation (PSFI) into the lumbar spine (L3/4) alter spinopelvic parameters compared with selective fusions to T12/L1/L2 in adolescent idiopathic scoliosis (AIS) patients.MethodsWe analysed radiographs of 84 AIS patients, 58 (69%) females and 26 (31%) males, who underwent PSFI at an mean age of 15 years ± 2.5 years, range 10 years to 21 years, between 1st January 2007 and 31st December 2014. Radiographic parameters were measured pre- and post-operatively at most recent follow-up (range 2 years to 8.2 years): pelvic incidence (PI), lumbar lordosis (LL, L1–S1 and L4–S1), sagittal vertical alignment (SVA), scoliosis angle and proximal junctional kyphosis (PJK). PI–LL was calculated. Data was analysed using t-tests or Wilcoxon rank-sum tests.ResultsIn total, 32 patients underwent a selective fusion with lowest instrumented vertebra (LIV) T12–L2, and 52 patients underwent a fusion with LIV L3–L4. In both groups, scoliosis angle was significantly corrected at follow-up (p < 0.005).Pre-operatively, both groups had similar LL (L1–S1) and PI–LL. Post-operatively, LL increased in the L3–4 fusion group (p < 0.005) but did not change in the selective fusion group (p = 0.116). This change in LL in the L3–4 fusion group affected the post-operative PI–LL (T12–L2 fusion -4.9° versus L3–4 fusion -13.6°, p = 0.002). No differences were seen in PI, SVA or LL L4–S1 between groups. Radiographic PJK occurred in seven of the L3–4 patients with and without PJK (noPJK –8.8° versus PJK –25.8°, p = 0.026).ConclusionsIn patients who underwent a fusion ending at L3 or L4, LL was increased. This altered the PI–LL relationship, and appeared to increase the risk of PJK.Level of evidenceIII

Risk Factors for Proximal Junctional Kyphosis Following Surgical Deformity Correction in Pediatric Neuromuscular Scoliosis.

Single-center retrospective cohort analysis. The aim of this study was to evaluate risk factors associated with the development of proximal junctional kyphosis (PJK) in pediatric neuromuscular scoliosis (NMS). PJK is a common cause of reoperation in adult deformity but has been less well reported in pediatric NMS. Sixty consecutive pediatric patients underwent spinal fusion for NMS with a minimum 2-year follow-up. PJK was defined as >10° increase between the inferior end plate of the upper instrumented vertebra (UIV) and the superior end plate of the vertebra two segments above. Regression analyses as well as binary correlational models and Student t tests were employed for further statistical analysis assessing variables of primary and compensatory curve magnitudes, thoracic kyphosis, proximal kyphosis, lumbar lordosis, pelvic obliquity, shoulder imbalance, Risser classification, and sagittal profile. The present cohort consisted of 29 boys and 31 girls with a mean age at surgery of 14 ± 2.7 years. The most prevalent diagnoses were spinal cord injury (23%) and cerebral palsy (20%). Analysis reflected an overall radiographic PJK rate of 27% (n = 16) and a proximal junctional failure rate of 7% (n = 4). No significant association was identified with previously suggested risk factors such as extent of rostral fixation (P = 0.750), rod metal type (P = 0.776), laminar hooks (P = 0.654), implant density (P = 0.386), nonambulatory functional status (P = 0.254), or pelvic fixation (P = 0.746). Significant risk factors for development of PJK included perioperative use of halo gravity traction (38%, P = 0.029), greater postoperative C2 sagittal translation (P = 0.030), decreased proximal kyphosis preoperatively (P = 0.002), and loss of correction of primary curve magnitude at follow-up (P = 0.047). Increase in lumbar lordosis from post-op to last follow-up trended toward significance (P = 0.055). Twenty-seven percent of patients with NMS developed PJK, and 7% had revision surgery. Those treated with halo gravity traction or with greater postoperative C2 sagittal translation, loss of primary curve correction, and smaller preoperative proximal kyphosis had the greatest risk of developing PJK.Level of Evidence: 4.

The Effect of Spinopelvic Parameters on the Development of Proximal Junctional Kyphosis in Early Onset: Mean 4.5-Year Follow-up.

Proximal junctional kyphosis (PJK) is a major complication after posterior spinal surgery. It is diagnosed radiographically based on a proximal junctional angle (PJA) and clinically when proximal extension is required. We hypothesized that abnormal spinopelvic alignment will increase the risk of PJK in children with early-onset scoliosis (EOS). A retrospective study of 135 children with EOS from 2 registries, who were treated with distraction-based implants. Etiologies included 54 congenital, 10 neuromuscular, 37 syndromic, 32 idiopathic, and 2 unknown. A total of 89 rib-based and 46 spine-based surgeries were performed at a mean age of 5.3±2.83 years. On sagittal radiographs, spinopelvic parameters were measured preoperatively and at last follow-up: scoliosis angle (Cobb method, CA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope and PJA. Radiographic PJK was defined as PJA≥10 degrees and PJA≥10 degrees greater than preoperative measurement. The requirement for the proximal extension of the upper instrumented vertebrae was considered a proximal junctional failure (PJF). Analysis of risk factors for the development of PJK and PJF was performed. At final follow-up (mean: 4.5±2.6 y), CA decreased (P<0.005), LL (P=0.029), and PI (P<0.005) increased, whereas PI-LL (pelvic incidence minus lumbar lordosis) did not change (P=0.706). Overall, 38% of children developed radiographic PJK and 18% developed PJF. Preoperative TK>50 degrees was a risk factor for the development of radiographic PJK (relative risk: 1.67, P=0.04). Children with high postoperative CA [hazard ratio (HR): 1.03, P=0.015], postoperative PT≥30 degrees (HR: 2.77, P=0.043), PI-LL>20 degrees (HR: 2.92, P=0.034), as well as greater preoperative to postoperative changes in PT (HR: 1.05, P=0.004), PI (HR: 1.06, P=0.0004) and PI-LL (HR: 1.03, P=0.013) were more likely to develop PJF. Children with rib-based constructs were less likely to develop radiographic PJK compared with children with spine-based distraction constructs (31% vs. 54%, respectively, P=0.038). In EOS patients undergoing growth-friendly surgery for EOS, preoperative TK>50 degrees was associated with increased risk for radiographic PJK. Postoperative PI-LL>20 degrees, PT≥30 degrees, and overcorrection of PT and PI-LL increased risk for PJF. Rib-based distraction construct decreased the risk for radiographic PJK in contrast with the spine-based constructs. Level III.

Cervical, Thoracic, and Spinopelvic Compensation After Proximal Junctional Kyphosis (PJK): Does Location of PJK Matter?

Study Design:Retrospective case series.Objective:Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment.Methods:Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment.Results:A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P = .01). The UT group displayed significant differences in all cervical radiographic parameters (P < .05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope–cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL.Conclusions:PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.

225. Global alignment and proportion score does not predict proximal junctional kyphosis

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) is a devastating complication of adult spinal deformity (ASD) surgery. Optimal alignment specifications to maximize quality of life while limiting PJK have yet to be defined. Previous studies have primarily examined sagittal vertical axis (SVA) to determine likelihood of PJK. More recently, other alignment parameters such as thoracic-pelvic angles (TPAs) and age-adjusted alignment have been examined. PURPOSE The goal of this study is to examine the relationship between GAP, TPAs, and bracing with likelihood of developing PJK. STUDY DESIGN/SETTING A retrospective chart review was conducted to identity ASD patients with at least 1 year of radiographic follow up. PATIENT SAMPLE Patients who underwent fusions to the pelvis and >4 levels fused from 2013 to 2018 and have 1-year postoperative alignment x-rays were included. OUTCOME MEASURES The rate of radiographic PJK (change of 10-20°) and severe PJK (change>20°) was determined for each group. Reoperation rates were also collected. METHODS Surgical records were reviewed to determine patient sample. Chart and X-ray review were conducted to determine spinopelvic alignment parameters, GAP scores, bracing, and reoperation. X-rays were reviewed up to one year postoperatively in order to determine PJK. RESULTS A total of 81 patients were included (mean 64y 63%F); baseline and 1-year postoperative alignment did not differ between PJK and no PJK patients. There was no PJK in 53.1%, 30.9% had PJK from 10-20°, and 16% had sPJK. Of these, 7 patients had revision surgery: 1 for PJK and 1 for rod fracture. Postop bracing was used in 54% of patients. There was no difference in sPJK according to brace use. At baseline, 79% of patients had severely disproportioned GAP, 16% moderate, 5% proportioned. Of severely disproportioned, 63% had no change in GAP at 1 year. Improved GAP was not associated with sPJK (improved: 22% vs no change: 18%, p=.72). Greater correction of the UIV-PA was associated with a larger PJK angle change (R=.26) as was the 1 year T1-UIV angle (R=.30), both p .05. CONCLUSIONS There was no correlation between PJK and GAP alone or change in GAP; it is notable that these patients tended to be disproportioned pre and postop. Greater correction of UIV-PA and larger postop T1-UIV was associated with greater PJKA change; suggesting that the greater alignment correction led to greater likelihood of it failing. Our data suggest bracing was not effective in preventing PJK. These parameters may help surgeons understand alignment targets in ASD. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Cervical Alignment Changes in Patients Developing Proximal Junctional Kyphosis Following Surgical Correction of Adult Spinal Deformity.

Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery is a well-documented complication, but associations between radiographic PJK and cervical malalignment onset remain unexplored. To study cervical malalignment in ASD surgical patients that develop PJK. Retrospective review of prospective multicenter database. Inclusion: primary ASD patients (≥5 levels fused, upper instrumented vertebra [UIV] at T2 or above, and 1-yr minimum follow-up) without baseline cervical deformity (CD), defined as ≥2 of the following criteria: T1 slope minus cervical lordosis < 20°, cervical sagittal vertical axis < 4 cm, C2-C7 cervical lordosis < 10°. PJK presence (<10° change in UIV and UIV + 2 kyphosis) and angle were identified 1 yr postoperative. Propensity score matching between PJK and nonPJK groups controlled for baseline alignment. Preoperative and 1-yr postoperative cervical alignment were compared between PJK and nonPJK patients. One hundred sixty-three patients without baseline CD (54.9 yr, 83.9% female) were included. PJK developed in 60 (36.8%) patients, with 27 (45%) having UIV above T7. PJK patients had significantly greater baseline T1 slope in unmatched and propensity score matching comparisons (P < .05). At 1 yr postoperative, PJK patients had significantly higher T1 slope (P < .001), C2-T3 Cobb (P = .04), and C2-T3 sagittal vertical axis (P = .02). New-onset CD rate in PJK patients was 15%, and 16.5% in nonPJK patients (P > .05). Increased PJK magnitude was associated with increasing T1 slope and C2-T3 SVA (P < .05). Patients who develop PJK following surgical correction of ASD have a 15% incidence of development of new-onset CD. Patients developing PJK following surgical correction of ASD tend to have an increased preoperative T1 slope. Increased progression of C2-T3 Cobb angle and C2-T3 SVA are associated with development of PJK following surgical correction of thoracolumbar deformity.

Friday, September 28, 2018 10:30 AM–12:00 PM abstracts: deformity: technical factors: 164. Incidence, risk factors and the natural history of proximal junctional kyphosis: review of long term surgical outcomes using hybrid fusion constructs for adolescent idiopathic scoliosis

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) is an unsolved radiographic phenomenon after corrective spinal deformity surgery with a high, but variable reported incidence. While known to influence outcomes in adults, the long-term clinical significance and natural history in children has not been well defined.Identifying incidence, risk-factors and natural course of PJK based on several proposed definitions in the literature using a large cohort may aid in enhancing our understanding of the disease entity. PURPOSE In a single-surgeon series of AIS patients undergoing deformity correction using hybrid hooks or screw constructs, the study attempted to identify potential risk-factors associated with the long-term development of PJK. Additionally, the study also defines PJK incidence and highlights the natural course of PJK development in children based on commonly proposed definitions in the literature. STUDY DESIGN/SETTING Retrospective, single-surgeon series with a minimum 2-year follow-up. PATIENT SAMPLE Overall, 253 eligible AIS patients with complete information on the proximal junctional angle (PJA) that underwent spinal deformity fusion (PSF) surgery by a single surgeon (SLW) at the University of Iowa between 2006 and 2015 that met the minimal criteria of 2-year follow-up were included. OUTCOME MEASURES The primary outcome was to assess incidence of PJK development form preoperative to postoperative measurements based on two commonly utilized definitions: Glattes et al. that defines PJK as PJA> 10°, and Bridwell et al. classification that defines the disease entity based on the critical PJA above 20°. Secondary outcome was to investigate factors associated with PJK development based on patient demographics, radiological indices and outcomes, and describe the natural course of PJK development in AIS patients undergoing deformity correction. METHODS AIS patients aged between 9 and 18 years undergoing primary long-construct PSF (UIV T2-4) between 2006 and 2015 with a minimum 2 years follow-up were included. Proximal junctional kyphosis was defined as a change in the PJA, according to Glattes et al. and Bridwell et al. classification from preop to postop. The incidence of PJK was defined at 6-week and last follow-up. Multivariable regression models were used to assess risk factors (patient characteristics, disease severity, radiographic parameters) associated with long-term PJK development. RESULTS A total of 253 eligible patients (mean age: 13.7 years; 82% female) with an average follow-up of 3.7 years (range: 24-123 months). Proximal junctional kyphosis (10°) occurred in 10.3% at 6 weeks (PJK 20: 0.4%) and 25.7% at final FU (PJK 20: 4.3%). Based on Glattes definition, a high proportion of patients developing PJK had Risser grade 3(19 vs. 6%; p=.003) and Lenke 5(13% vs. 5%; p=.028) at baseline. In an unadjusted analysis, Risser grade 3(OR:3.6; p=.01), Lenke 5(OR:3.0; p=.03) and those with UIV as T4 (vs. T2) were associated with higher odds of PJK development. In multivariable model, we noted Risser grade 3(OR:4.6; p=.045) as a factor for PJK development. Low reoperation rate (0.04%;1/253) was noted. CONCLUSIONS PJK after AIS deformity surgery varies according to follow up time and definition. In contrast to adults, there does not appear to be any clear risk factors for PJK in an AIS population. Long-term reoperation for PJK appears to be exceedingly low at 0.4%. Radiographic PJK should be followed but generally thought of a benign condition in pediatric deformity surgery. Likely risk factors for PJK include short instrumentation (upto T4 compared to T2), Risser grade 3 and Lenke 5. Consensus on PJK definition is warranted to better define the pathological entity.

Comprehensive Assessment of Outcomes From Patients With Severe Early-onset Scoliosis Treated With a Vertebral Column Resection: Results From an SRS Global Outreach Site (FOCOS) in Ghana

Early-onset scoliosis (EOS) remains a challenging pediatric spine condition to manage. Some severe deformities can be managed with a vertebral column resection (VCR), which is fraught with high complication rates and the outcomes have not been well reported. The purpose of this study is to provide an assessment of operative, radiographic, and clinical outcomes from children diagnosed with severe EOS treated with a VCR. We performed a retrospective review of prospectively collected data. Basic demographic data was collected along with the diagnosis, procedure performed, FOCOS risk score, blood loss (estimated blood loss), operative time, neuromonitoring events, intraoperative complications, and clinical follow-up. Coronal and sagittal radiographic parameters were measured by the first author. We identified 14 patients with posttuberculosis deformity (n=7) or congenital deformity (n=7) that underwent VCR between 2013 and 2016 (5 female; age, 7.7±3 y; body mass index, 17.7±2.8). There was significant improvement in coronal radiographic parameters (primary curve: 55 to 21 degrees, secondary: 37 to 13 degrees, T1-12 length: 137 to 151 mm, T1-S1 length: 219 to 271 mm, P<0.05) and sagittal parameters (kyphosis: 85 to 41 degrees, compensatory lordosis 56 to 39 degrees, P<0.001). There was no change in chest width, sagittal vertical axis, or pelvic tilt. Mean proximal junctional kyphosis (PJK) angle was 12±9 degrees and distal junctional kyphosis angle was 9±17 degrees. Estimated blood loss was 860±520 mL and operative time was 200±66 minutes. Seven cases had neuromonitoring changes that improved with corrective maneuvers and blood pressure elevation. Three patients required reoperation for junctional breakdown with 1 having a third operation for an infection, while 2 additional patients had evidence of radiographic PJK. VCR in the setting of EOS has excellent radiographic outcomes but a high complication profile. Half of these cases had neuromonitoring changes intraoperatively that improved without lasting neurological deficit. Three patients had PJK and 1 had an infection requiring reoperation. Level IV-case series.