Proximal Junctional Kyphosis Groups Research Articles

Spinopelvic morphology impacts on postoperative proximal junctional kyphosis in congenital scoliosis with thoracolumbar hemivertebrae.

It aims to investigate the lumbar and pelvic morphology in congenital scoliosis with thoracolumbar hemivertebrae and its impact on proximal junctional kyphosis (PJK) incidence after hemivertebra resection and short fusion. 23 congenital scoliosis patients with thoracolumbar hemivertebra aged between 10 and 18years were enrolled in the retrospective study. Spinopelvic sagittal parameters were analyzed on whole-spine standing lateral radiographs preoperatively, one-week postoperatively and at the final follow-up. Pearson correlations were calculated for local kyphosis (LK), lumbar and pelvic morphology parameters. Binary logistic regression and receiver operating characteristics (ROC) curve analysis were performed to identify the risk factors for PJK. Thoracolumbar hemivertebra caused LK of 29.2° ± 17.3°, an increased lumbar lordosis (LL) (-64.7° ± 16.3°), lower LL apex (52.2% at L5), and small pelvic incidence (PI) (36.8° ± 6.6°). LK was correlated with lumbar morphology parameters, including LL (r = -0.837), upper arc of LL (LLUA) (r = -0.879), thoracolumbar kyphosis (TLK) (r = 0.933), thoracic kyphosis (TK) (r = 0.762) and TK apex (TKA) (r = -0.749). Surgical treatment improved the lumbar morphology, but not pelvic morphology. At the final follow-up, LL had returned to its preoperative value (p = 0.158). PJK occurred in 30.4% of cases as a compensatory mechanism. Preoperatively, significant differences of parameters between non-PJK and PJK groups were observed in LK and TLK. Binary logistic regression identified three independent risk factors for PJK: preoperative LLA (OR = 0.005, 95%CI = 0.000-0.287, p = 0.011), preoperative TLK (OR = 1.134, 95%CI = 1.001-1.286, p = 0.048), and preoperative lumbar lordosis morphology type (OR = 5.507, 95%CI = 1.202-25.227, p = 0.028). However, residual LK after surgery was not correlated with PJK incidence. ROC curve analysis verified that preoperative TLK > 22.59° was associated with increased PJK incidence after surgery. Lumbar morphology changes as a compensatory mechanism beneath the thoracolumbar hemivertebra. However, a stable pelvis tends to allow the LL to return to its preoperative value. PJK occurred as a cranial compensatory mechanism for increasing LL and corrected TLK. A larger TLK (> 22.59°) was an independent risk factor for PJK incidence in patients with type 2 and 3A lumbar lordosis morphology.

Introduction of a New Radiographic Parameter to Predict Proximal Junctional Kyphosis in Adult Spinal Deformity: UIVPTA (Uppermost Instrumented Vertebra-Pelvic Tilt Angle).

To introduce a new sagittal parameter, uppermost instrumented vertebra-pelvic tilt angle (UIVPTA), and to determine the effects on the proximal junctional kyphosis (PJK) development in adult spinal deformity (ASD) surgery. Patients ≥ 60 years with ASD who underwent low thoracic spine to pelvis fusion with a minimum of 2-years of follow-up were included in this study. Two groups were created according to PJK development. Various clinical and radiographic factors were compared between PJK and non-PJK groups to identify the risk factors for PJK. Cutoff value of UIVPTA for PJK development was calculated using receiver operating characteristic curve according to different pelvic incidence groups. Linear regression analysis was performed to identify factors to affect UIVPTA. One hundred fifity-one patients were included in this study. There were 135 female patients (89.4%). Mean age was 70.5 years. PJK developed in 65 patients (43.0%). Multivariate analysis showed that overcorrection relative to age-adjusted pelvic incidence (PI) minus lumbar lordosis (LL) (PI-LL) target and lower UIVPTA were independent risk factors for PJK. The cutoff value of UIVPTA for PJK development was calculated as 4.0° in patients with PI less than 45°, 9.5° in patients with PI between 45° and 60°, and 13.0° in patients with PI greater than 60°. Linear regression analysis showed that UIVPTA was positively affected by postoperative values of LL (coefficient = 0.505), PI-LL (coefficient = 0.674), and pelvic tilt (coefficient = 0.286). Optimal correction within the age-adjusted PI-LL combined with keeping UIVPTA within optimal range is suggested for the prevention of PJK.

Vertebral bone quality score as a novel predictor of proximal junctional kyphosis after thoracic adolescent idiopathic scoliosis surgery.

Proximal junctional kyphosis (PJK) is one of the most common complications after thoracic AIS surgery. Previous studies reported that the etiology of PJK was associated with osteopenia and meanwhile the AIS patients were found osteopenia which could persist into adulthood. Recently, an MRI-based vertebral bone quality score (VBQ) was reported to be a promising tool which can assess preoperative bone quality. This study aims to evaluate the utility of VBQ score in predicting PJK after corrective surgery for thoracic AIS (Lenke 1 and 2). We conducted a retrospective study to identify the predictive efficiency of VBQ score for PJK in thoracic AIS patients. Demographic, radiographic parameters, and surgical variables were collected. VBQ score was calculated using preoperative T1-weighted MRI. Univariate analysis, linear regression, and multivariate logistic regression were performed to determine potential risk factors of PJK and correlation between other parameters and VBQ score. Receiver operating characteristic analysis and area under the curve values were utilized to evaluate the predictive efficiency of VBQ score for PJK. A total of 206 patients (aged 14.4 ± 2.3years) were included, of which 33 (16.0%) developed PJK. VBQ scores were significantly different between the PJK and non-PJK groups (2.8 ± 0.2 vs 2.5 ± 0.2, P < 0.01). A significant positive correlation was found between VBQ score and PJA (R2 = 0.1728, P < 0.01).On multivariate analysis, VBQ score was the only significant predictor of PJK (odds ratio = 2.178, 95% CI = 1.644-2.885, P < 0.001), with a predictive accuracy of 83%. Higher VBQ scores were independently associated with PJK occurrence after corrective surgery for thoracic AIS. Preoperative measurement of VBQ score on MRI may serve as a valuable tool in planning thoracic AIS surgery.

Analysis of factors associated with proximal junctional kyphosis after surgery for Lenke type 5 adolescent idiopathic scoliosis

Objective: To investigate the risk factors associated with the development of proximal junctional kyphosis (PJK) after posterior spinal fusion for in children with Lenke type 5 adolescent idiopathic scoliosis (AIS). Methods: It was a retrospective case-control study that included medical records of 98 children with Lenke type 5 AIS who underwent posterior orthopedic surgery under general anesthesia at the Honghui Hospital Affiliated to Xi'an Jiaotong University from January 2013 to December 2018. There were 23 males and 75 females with a mean age of (14.5±2.2) years (10-18 years). Patients were divided into PJK and non-PJK groups according to whether the posterior junctional angle (PJA) was greater than 10° and increased for more than 10° from the preoperative period at the the last follow-up. Univariate analysis was used to analyze the correlation of general data of the children with occurrence of PJK after the operation. Multivariate logistic regression analysis was used to analyze the risk factors of postoperative PJK. Results: There were 35 cases in the PJK group and 63 cases in the non-PJK group. The PJK and non-PJK groups were followed up for (35.6±7.3) months and (36.4±7.5) months, respectively, and the difference was not statistically significant (P=0.637). There was no statistically significant difference between the two groups in general data such as gender, age, and body mass index (all P>0.05), while there were statistically significant differences between the two groups in upper instrumented vertebrea (UIV) location and junctional area posterior ligamentous complex (PLC) injury (all P<0.05). The results of univariate analysis showed that UIV location at T10-T12, junctional area PLC injury, preoperative coronal thoracic curve (TC), preoperative and final follow-up PJA, and preoperative and final follow-up pelvic incidence-lumbarlordosis (PI-LL) were correlated with postoperative PJK (OR=2.50, 5.37, 0.92, 1.12, 1.32, 1.06, 3.35, all P<0.05). Multifactorial logistic regression analysis showed that UIV located at T10-T12 (OR=2.346, 95%CI: 1.582-3.481, P=0.001), junctional area PLC injury (OR=5.112, 95%CI: 1.283-20.418, P=0.023) and last follow-up PI-LL (OR=1.826, 95%CI: 1.558-24.745, P=0.012) were risk factors for the occurrence of postoperative PJK in children with Lenke type 5 AIS. Conclusions: Postoperative UIV fixation to the thoracolumbar segment, PLC injury in the junctional area and excessive postoperative PI-LL in children with Lenke type 5 AIS may be the risk factors for the occurrence of PJK after the operation. It is suggested that avoidance of UIV selection to the thoracolumbar segment, intraoperative protection of the PLC located near the UIV and restoration of a good PI-LL relationship may reduce the incidence of PJK.

The Relationship between the Hounsfield Units Value of the Upper Instrumented Vertebra and the Severity of Proximal Junctional Fracture after Adult Spinal Deformity Surgery.

Background and Objectives: In this retrospective cohort study, we investigate associations between the Hounsfield units (HU) value of upper instrumented vertebra (UIV) and proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery. Materials and Methods: The cohort consisted of 60 patients (mean age 71.7 years) who underwent long instrumented fusion surgery (≥6 vertebrae) for ASD with at least 1 year of follow-up. The preoperative bone mineral density (BMD) measured on DXA scans, the HU values at UIV and UIV+1, and the radiographic parameters were compared between the PJK and non-PJK groups. The severity of UIV fracture was assessed using a semiquantitative (SQ) grade. Results: PJK occurred in 43% of patients. No significant differences in patient age, sex, BMD, and preoperative radiographic parameters were observed between the PJK and non-PJK groups. The HU values of the UIV (103.4 vs. 149.0, p < 0.001) and UIV+1 (102.0 vs. 145.7, p < 0.001) were significantly lower in the PJK group. The cutoff values of HU at UIV and UIV+1 were 122.8 and 114.9, respectively. Lower HU values at UIV (Grade 1: 134.2, Grade 2: 109.6, Grade 3: 81.1, p < 0.001) and UIV+1 (Grade 1: 131.5, Grade 2: 107.1, Grade 3: 82.1, p < 0.001) were associated with severe SQ grade. Conclusions: Lower HU values at UIV and UIV+1 had a negative impact on signal incidence of PJK and were correlated with the severity of UIV fractures. Preoperative treatment of osteoporosis seems necessary for preoperative UIV HU values less than 120.

Unmatched rod contouring at the proximal end predisposes to occurrence of junctional kyphosis in early-onset scoliosis patients undergoing traditional growing rods treatment

Study designA retrospective case series.ObjectiveTo investigate whether unmatched rod contouring at the proximal end predisposed to the occurrence of proximal junctional kyphosis (PJK) in early-onset scoliosis (EOS) patients after traditional growing rods (TGR) treatment.Summary of background dataTGR treatment has become a mainstay of treatment for EOS patients. PJK is one of the most common alignment-related complications.MethodsA consecutive series of EOS patients who had undergone TGR treatment were retrospectively reviewed. They were divided into PJK and non-PJK groups according to the occurrence of PJK or not. Demographic data, surgical strategies, and radiographic parameters were recorded and compared between groups. Proximal junctional angle (PJA) was defined as the angle between the caudal endplate of the UIV and the cephalad endplate of the second supradjacent vertebra above the UIV, while proximal rod contouring angle (PRCA) was defined as the angle of proximal rod contouring, which was represented by the angle between the cephalad endplate of the UIV and the caudal endplate of the second vertebra caudal to the UIV. Unmatched proximal rod contouring was regarded if the postoperative PRCA-PJA difference was greater than 5°.ResultsThis study finally included 73 patients. The mean age at the index surgery was 6.5 ± 2.2 years (range, 2–10 years). Mean follow-up lasted 5.0 ± 1.7 years (range, 2–9 years). They received mean 4.6 ± 1.6 lengthening procedures. There were 13 patients who were observed with PJK (18%). In comparison with the non-PJK group, the PJK group showed a larger preoperative major curve (82 ± 21° vs 70 ± 17°, P = 0.041) and global kyphosis (57 ± 6° vs. 44 ± 15°, P = 0.044). In addition, the PJK group had significantly larger postoperative PJA (10 ± 3 vs. 5 ± 3, P<0.001) and greater postoperative PJA-PRCA (6 ± 3 vs. 3 ± 3, P = 0.031). The proportion of patients with unmatched proximal rod contouring in PJK group was significantly higher than that in the non-PJK group (69% vs. 25%). Multiple logistic regression showed that preoperative GK>50°, postoperative PJA>10 and postoperative unmatched proximal rod contouring were the risk factors in predicting PJK after TGR treatment.ConclusionApproximately 18% EOS patients experienced PJK after TGR treatment. Unmatched proximal rod contouring may be an independent risk factor of PJK occurrence, in addition to greater preoperative GK and larger postoperative PJA.Level of evidence3.

190. C2 pelvic angle (C2PA) is a useful radiographic parameter that correlates with clinical outcomes of symptomatic proximal junctional kyphosis

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) after spine deformity surgery is a radiographic phenomenon defined based on the proximal junctional angle (PJA). Currently, there is minimal literature demonstrating correlation between clinical outcome scores and PJA. The lack of correlation may be due to the inadequate assessment of global spinal alignment from the PJA. The C2PA is a novel radiographic angle that portrays the mismatch between the global spinal alignment and alignment proximal to the spine that corresponds with ODI and SRS scores. <h3>PURPOSE</h3> The definition of PJK after spine deformity surgery is based on the PJA. Despite the growing amount of literature on PJK, minimal correlation exists between PJK and clinical outcome scores. PJA poorly represents, and is difficult to measure, PJK for global spinal alignment after deformity surgery. C2PA is a novel radiographic angle that demonstrates the difference between global spinal alignment and alignment proximal to the spinal construct. <h3>STUDY DESIGN/SETTING</h3> Prospectively collected cohort. <h3>PATIENT SAMPLE</h3> A radiographic review was performed on 98 deformity patients from July 2015-July 2018. <h3>OUTCOME MEASURES</h3> Logistic regression and Chi-square analyses were performed to study the relationship between the postop PJA and C2PA with ODI/SRS scores. <h3>METHODS</h3> A radiographic review was performed on 98 deformity patients from July 2015-July 2018. The angle between the posterior superior sacrum, C2 centroid and upper instrumented vertebrae (UIV) centroid in the pre- and postop setting (2-year or prior to return to OR) were measured and labeled as C2PA. The patients were divided into PJK and non-PJK groups based on (a) PJK defined as PJA >20° and (b) PJK defined as C2PA >20°. Logistic regression and Chi-square analyses were performed to study the relationship between the postop PJA and C2PA with ODI/SRS scores. <h3>RESULTS</h3> Of the 98 patients, there were 20 patients with PJK when it was defined as PJA >20°. There was no statistically significant correlation between ODI and SRS scores in the non-PJK and PJK group when it was defined as PJA. There were minimal differences between the ODI scores (8.0 vs 7.0, p=0.66) and the SRS total scores (71.3 vs 70.6, p=0.85) in the Non-PJK and PJK group when it was defined as PJA >20°. When PJK was defined as C2PA >20°, there were 31 patients with PJK. There were statistically significant differences between the non-PJK and PJK group for both ODI (8.0 vs 16.0, p=0.015) and SRS total scores (97.0 vs 88.0, p=0.010) when PJK was defined as C2PA >20° <h3>CONCLUSIONS</h3> This is the first study demonstrating that C2PA is a superior radiographic representation of PJK, and directly correlates with patient-reported outcomes. C2PA >20° is the critical angle that corresponds with clinical PJK. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P101. Pseudarthrosis and rod fracture at the distal levels of a long construct are associated with proximal junctional kyphosis after ASD surgery

<h3>BACKGROUND CONTEXT</h3> More distal fusion levels and overall stiffness of a long fusion construct for ASD may result in larger range of motion and stress at the proximal junctional level. Stability of distal fixation, inferred by the presence or absence of pseudarthrosis and rod fracture, may affect proximal junctional stresses and contribute to proximal junctional kyphosis (PJK) and associated revision surgery.To date, very few studies have evaluated the relationship between achieving solid fusion at the base of a long construct and rate of PJK. <h3>PURPOSE</h3> To assess the relationship between lumbosacral rod fracture and pseudarthrosis and development of proximal junctional kyphosis (PJK) after long construct ASD surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively collected single center database. <h3>PATIENT SAMPLE</h3> We performed a review of 942 patients who underwent ASD surgery (Age: 55 ± 23 y; mFI: .41 ± .67; Levels fused: 10.1 ± 4.2; Revision: 22.3%; 3CO: 12.3%). <h3>OUTCOME MEASURES</h3> We assessed the rate of PJK at minimum 2-year follow-up, as well as the rate of pseudarthrosis or rod fracture at the lower lumbar levels or lumbosacral junction, and the association between these complications. <h3>METHODS</h3> A total of 942 patients were divided into PJK and non-PJK groups using whole spine standing radiographs. The incidences of PJK, and lumbar or lumbosacral pseudarthrosis were defined. The relationship between these complications was assessed. <h3>RESULTS</h3> The cohort had sagittal malalignment as demonstrated by PT 23.7 ± 12.4°, TPA 22.5 ± 26.2°, and SVA 77.8 ± 70 mm. The PJK and non-PJK groups comprised 350 and 592 cases respectively. Mean follow-up time was 48.9 months. There was no significant difference in baseline SVA, T1 pelvic angle, change in sagittal alignment postoperatively, and surgical invasiveness index between the two groups. There were 11.1% of patients who developed PJK had a pseudarthrosis at the lower lumbar levels or lumbosacral junction, versus 6.4% of those who did not develop PJK (p=0.011). Patients who developed PJK had a significantly higher rate of rod fracture in the lower lumbar levels or lumbosacral junction (15.4%) versus those who did not develop PJK (7.3%) (p<0.0001). Pseudarthrosis (OR: 1.963, 95% CI: 1.14-3.38, p=0.015) and rod fracture at the lower lumbar levels or lumbosacral junction (OR: 2.27, 95% CI: 1.41-3.64, p=0.001) were predictors of PJK at final follow-up by regression analysis. <h3>CONCLUSIONS</h3> Pseudarthrosis and rod fracture at the lower lumbar levels or lumbosacral junction were predictive of development of PJK at final follow-up. This may indicate that distal stability of a long construct has a significant impact on stresses at the proximal junction. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Risk and Predictive Factors for Proximal Junctional Kyphosis in Patients Treated by Lenke Type 5 Adolescent Idiopathic Scoliosis Correction

Proximal junctional kyphosis (PJK) is a common sagittal complication of adolescent idiopathic scoliosis (AIS) after corrective surgery, leading to new deformities, pain, and, even, revision surgery. In the present study, we investigated the risk and predictive factors for PJK in patients who had undergone Lenke type 5 AIS correction to identify the parameters relevant to intraoperative guidance. A total of 35 patients with Lenke type 5 AIS who had undergone corrective surgery at our hospital from January 2008 to February 2016 were divided into the PJK (n= 15) and non-PJK (n= 20) groups. Correlation and receiver operating characteristic curve analyses were performed to screen the parameters for significance and calculate the thresholds. A survival analysis was performed to examine the differences between the 2 groups. Independent t tests revealed significant differences between the 2 groups in the preoperative pelvic incidence, preoperative pelvic tilt, postoperative proximal junctional angle (PJA), and postoperative thoracic kyphosis (TK). The postoperative PJA, postoperative TK, and other parameters correlated significantly with changes in the PJA at the final follow-up. The receiver operating characteristic curves revealed that the postoperative PJA and postoperative TK effectively predicted for the occurrence of PJK, with a threshold of 9.45° and 25.25°, respectively. The estimated survival times were 14.7 months for a PJA >9.45° and TK >25.25°, 19.2 months for a PJA >9.45°, and 33.9 months for TK >25.25°. The results of the present study have shown that the postoperative PJA and postoperative TK can be used to effectively predict for the occurrence of PJK in patients with Lenke type 5 AIS after corrective surgery, with a threshold of 9.45° and 25.25°, respectively.

Prediction of Proximal Junctional Kyphosis After Posterior Scoliosis Surgery With Machine Learning in the Lenke 5 Adolescent Idiopathic Scoliosis Patient.

ObjectiveTo build a model for proximal junctional kyphosis (PJK) prognostication in Lenke 5 adolescent idiopathic scoliosis (AIS) patients undergoing long posterior instrumentation and fusion surgery by machine learning and analyze the risk factors for PJK.Materials and MethodsIn total, 44 AIS patients (female/male: 34/10; PJK/non-PJK: 34/10) who met the inclusion criteria between January 2013 and December 2018 were retrospectively recruited from West China Hospital. Thirty-seven clinical and radiological features were acquired by two independent investigators. Univariate analyses between PJK and non-PJK groups were carried out. Twelve models were built by using four types of machine learning algorithms in conjunction with two oversampling methods [the synthetic minority technique (SMOTE) and random oversampling]. Area under the receiver operating characteristic curve (AUC) was used for model discrimination, and the clinical utility was evaluated by using F1 score and accuracy. The risk factors were simultaneously analyzed by a Cox regression and machine learning.ResultsStatistical differences between PJK and non-PJK groups were as follows: gender (p = 0.001), preoperative factors [thoracic kyphosis (p = 0.03), T1 slope angle (T1S, p = 0.078)], and postoperative factors [T1S (p = 0.097), proximal junctional angle (p = 0.003), upper instrumented vertebra (UIV) – UIV + 1 (p = 0.001)]. Random forest using SMOTE achieved the best prediction performance with AUC = 0.944, accuracy = 0.909, and F1 score = 0.667 on independent testing dataset. Cox model revealed that male gender and larger preoperative T1S were independent prognostic factors of PJK (odds ratio = 10.701 and 57.074, respectively). Gender was also at the first place in the importance ranking of the model with best performance.ConclusionThe random forest using SMOTE model has the great value for predicting the individual risk of developing PJK after long instrumentation and fusion surgery in Lenke 5 AIS patients. Moreover, the combination of the outcomes of a Cox model and the feature ranking extracted by machine learning is more valuable than any one alone, especially in the interpretation of risk factors.

Under-contouring of rods: a potential risk factor for proximal junctional kyphosis after posterior correction of Scheuermann kyphosis.

Scheuermann kyphosis (SK) could require surgical treatment in certain situations. A posterior reduction is the most widespread treatment so far, although the development of proximal junctional kyphosis (PJK) is one of the possible complications of this procedure. The contour of the proximal part of the rod could influence the occurrence of PJK in SK patients. The objective of this study was to analyze the impact of the proximal rod contour on the occurrence of a PJK complication in SK patients. This retrospective monocentric study was performed in the Nanjing Spine Surgery Department. All eligible patients had undergone posterior correction surgery with pedicle screws only between 2002 and 2017 and had at least 24 months of follow-up. The presence of PJK was quantified on radiographs using the proximal junctional angle (PJA > 10° at the last follow-up). The authors propose a new radiological parameter to measure the angulation of the proximal part of the instrumentation: the proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to the UIV. The patients were analyzed according to the presence or absence of PJK. A t-test, receiver operating characteristic (ROC) curve analysis, and logistic regression analysis were performed for statistical analysis. Sixty-two patients treated for SK were included in this study. The mean age was 18.6 ± 8.5 years, and the mean follow-up was 42.5 ± 16.4 months. The mean correction rate of global kyphosis was 46.4% ± 13.7%. At the last follow-up, 17 patients (27.4%) presented with PJK. No significant difference was found between the PJK and non-PJK groups in terms of age and other preoperative variables. A significant difference in the postoperative PCRA was found between the PJK and non-PJK groups (8.2° ± 4.9° vs 15.7° ± 6.6°, respectively; p = 0.001). A postoperative PCRA less than 10.1° predicted a significantly higher risk for PJK (p = 0.002, OR 2.431, 95% CI 1.781-4.133). Under-contouring of the proximal part of the rods (lower than 10°) is a risk factor for PJK after posterior correction of SK.

Effect of sagittal shape on proximal junctional kyphosis following thoracopelvic corrective fusion for adult spinal deformity: postoperative inflection vertebra cranial to T12 is a significant risk factor.

This was a retrospective analysis of a prospectively collected consecutive case series of patients with adult spinal deformity (ASD). This study aimed to investigate the impact of the geometrical sagittal shape of the corrected spine on the development of proximal junctional kyphosis (PJK). Several studies have documented risk factors for PJK in ASD surgery. Geometrical assessment is vital for evaluating sagittal spinal deformity. It is essential to assess the postoperative geometrical shape of the spine and the location of the correction in the spine to decrease postoperative junctional stress and PJK. Consecutive patients with ASD who underwent corrective fusion with long constructs to the pelvis were included. Patients with neuromuscular disease, congenital and adolescent scoliosis, infection, and spinal tumor were excluded. We investigated the spinopelvic and geometrical parameters of the whole spine. The locations of the thoracic and lumbar apical vertebrae and the inflection vertebrae (IV), where the curvature of the associated adjacent vertebral bodies changes from kyphosis to lordosis, were investigated. The subjects were divided into PJK included patients who underwent revision surgery for junctional failure or with a change in proximal junctional angle ≥ 20°, and non-PJK groups. A total of 139 patients (mean age, 69.6years; range 18-82years) were included. There were 47 and 92 patients in the PJK and non-PJK groups, respectively. The IV were located significantly cranial and posterior, the lumbar apex were located significantly posterior in the PJK group at the immediate postoperative time points. The significant risk factors for PJK on binary logistic regression were cranial IV and posterior lumbar apical vertebrae. The incidence of PJK in patients with IV at T12 or cranial tends PJK significantly higher (69%) than at L1 or caudal (26%). Geometrical spinal shape should be taken into account to reduce the rate of postoperative mechanical complications. Level of evidence III.

The Risk of Proximal Junctional Kyphosis Decreases in Patients With Optimal Thoracic Kyphosis

Study DesignA retrospective study of surgical outcomes. ObjectiveThis study aimed to investigate the preoperative risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) surgery. Summary of Background DataThe cause of PJK is still unclear, although some risk factors have been reported in ASD surgery. MethodsA total of 185 patients who were followed up for more than two years and underwent ASD surgery were recruited. PJK was defined as a proximal junctional angle ≥20° or reoperation due to PJK within two years after surgery. These patients were divided into PJK and non-PJK groups. Whole-spine standing radiography was performed before and immediately, one year, and two years after the surgery. ResultsThe PJK and non-PJK groups comprised 58 and 127 cases, respectively. The incidence of PJK demonstrated significant differences according to preoperative thoracic kyphosis (TK): 37% (TK ≤19°), 33% (TK 20°–29°), 9% (TK 30°–39°), 32% (TK 40°–49°), and 41% (TK ≥50°) (p < .05). Logistic regression analysis suggested that the amount of change in TK before and just after the surgery (ΔTK) was a significant risk factor for PJK (p < .001; odds ratio 1.062, 95% confidence interval 1.029–1.097). ConclusionΔTK was less in the TK group of 30°–39° because the TK of patients who underwent ASD surgery converged to 34.5° just after surgery. Consequently, a lower or higher TK was likely to result in a large ΔTK just after surgery. Therefore, patients who had an optimal TK (30°–39°) had a lower risk of PJK. Level of EvidenceLevel IV.

Location of correction within the lumbar spine impacts acute adjacent-segment kyphosis.

OBJECTIVEThe surgical correction of adult spinal deformity (ASD) often involves modifying lumbar lordosis (LL) to restore ideal sagittal alignment. However, corrections that include large changes in LL increase the risk for development of proximal junctional kyphosis (PJK). Little is known about the impact of cranial versus caudal correction in the lumbar spine on the occurrence of PJK. The goal of this study was to investigate the impact of the location of the correction on acute PJK development.METHODSThis study was a retrospective review of a prospective multicenter database. Surgically treated ASD patients with early follow-up evaluations (6 weeks) and fusions of the full lumbosacral spine were included. Radiographic parameters analyzed included the classic spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], PI-LL, and sagittal vertical axis [SVA]) and segmental correction. Using Glattes' criteria, patients were stratified into PJK and noPJK groups and propensity matched by age and regional lumbar correction (ΔPI-LL). Radiographic parameters and segmental correction were compared between PJK and noPJK patients using independent t-tests.RESULTSAfter propensity matching, 312 of 483 patients were included in the analysis (mean age 64 years, 76% women, 40% with PJK). There were no significant differences between PJK and noPJK patients at baseline or postoperatively, or between changes in alignment, with the exception of thoracic kyphosis (TK) and ΔTK. PJK patients had a decrease in segmental lordosis at L4-L5-S1 (-0.6° vs 1.6°, p = 0.025), and larger increases in segmental correction at cranial levels L1-L2-L3 (9.9° vs 7.1°), T12-L1-L2 (7.3° vs 5.4°), and T11-T12-L1 (2.9° vs 0.7°) (all p < 0.05).CONCLUSIONSAlthough achievement of an optimal sagittal alignment is the goal of realignment surgery, dramatic lumbar corrections appear to increase the risk of PJK. This study was the first to demonstrate that patients who developed PJK underwent kyphotic changes in the L4-S1 segments while restoring LL at more cranial levels (T12-L3). These findings suggest that restoring lordosis at lower lumbar levels may result in a decreased risk of developing PJK.

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.

Clinical and radiographic presentation and treatment of patients with cervical deformity secondary to thoracolumbar proximal junctional kyphosis are distinct despite achieving similar outcomes: Analysis of 123 prospective CD cases

CD development secondary to PJK was recently documented in adult spinal deformity patients after surgical correction for thoracolumbar ASD. This study analyzes surgical management of patients with CD secondary to proximal junctional kyphosis (PJK) versus patients with primary CD. Retrospective review of multicenter cervical deformity (CD) database. CD defined as at least one of the following: C2–C7 coronal Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4cm, CBVA > 25°. Patients were grouped into those with PJK (UIV +2 < −10°) prior to cervical surgery versus who don’t (Non-PJK). Independent t-tests and chi-squared tests compared radiographic, clinical, and surgical metrics between PJK and non-PJK groups. Of 123 eligible CD patients, 26(21.1%) had radiographic PJK prior to cervical surgery. PJK patients had significantly greater T2–T12 thoracic kyphosis (−58.8° vs −45.0°, p = 0.002), cSVA (49.1 mm vs 38.9 mm, p = 0.020), T1 Slope (42.6° vs 28.4°, p < 0.001), TS-CL (44.1° vs 35.6°, p = 0.048), C2-T3 SVA (98.8 mm vs 75.8 mm, p = 0.015), C2 Slope (45.4° vs 36.0°, p = 0.043), and CTPA (6.4° vs 4.6°, p = 0.005). Comparing their surgeries, the PJK group had significantly more levels fused (10.7 vs 7.4, p = 0.01). There was significantly greater blood loss in PJK patients (1158 ± 1063vs 738 ± 793 cc, p = 0.028); operative time, surgical approach, and BMP-2 use were similar (all p > 0.05). PJK patients experienced higher rates of complications 30 and 90 days post-operatively (23.1% vs. 5.2%, p = 0.004; 30.8% vs. 19.6%, p = 0.026), and more instrumentation failure 30 days postoperatively (7.8% vs. 1.0%, p = 0.004). Patients with cervical deformity secondary to PJK had worse baseline CD, despite no differences in HRQL or demographics. Surgical correction of CD associated with PJK required more invasive surgery and had higher complication rates than non-PJK patients, despite achieving similar clinical outcomes.

Proximal junctional kyphosis following correction surgery in the Lenke 5 adolescent idiopathic scoliosis patient

BackgroundTo investigate the risk factors of proximal junctional kyphosis (PJK) in Lenke 5 AIS patients after all-pedicle instrumentation and correction, and to compare the difference of radiographic and clinical outcome between PJK and Non-PJK populations. MethodMedical records of Lenke 5 AIS patients were reviewed from January 2008 to January 2013, included posteroanterior and lateral full spine X-ray films preoperatively, postoperatively (4–7 days after surgery), and at final follow-up. Demographic data and radiologic parameters were evaluated. Based on the proximal junctional angle (PJA) at final follow-up, those patients were divided into 2 groups: PJK group (n = 35, PJA≧10°), and Non-PJK group (n = 52, PJA<10°). Comparisons analyses between PJK and Non-PJK groups were carried out. Binary logistic Regression analysis was performed to detect the risk factors of PJK at follow-up. ResultsThe current study recruited 87 Lenke 5 AIS patients with average follow-up of 4.67 ± 1.17 years. Significant differences between PJK and Non-PJK groups were observed as follows: UIV(P = 0.010), the disruption of junctional ligaments (P < 0.001); preoperative variables [MTC (P = 0.001), TK(P < 0.001), LL (P = 0.017), SVA (P = 0.036), and PJA (P = 0.014)], postoperative variables [TLK(P = 0.004), and PJA (P < 0.001)], and follow-up [SVA (P = 0.014), C-SVA (P < 0.001), and PJA (P0.001). Binary logistic regression showed that the disruption of junctional ligaments, postoperative PJA and UIV (upper instrumented vertebra) at proximal or lower thoracic levels were the main risk factors of PJK [Odds Ratio (OR) = 5.114, 2.345, and 6.212, respectively]. However, the SRS-22 scores did not change significantly in PJK and Non-PJK groups. ConclusionGreater postoperative PJA, disruption of junctional ligaments, UIV at lower thoracic levels were the main risk factors for PJK in Lenke 5 AIS patients. Recommedation: Preserve junctional ligaments in those individuals with UIV located in the lower thoracic region.

Proximal junctional kyphosis in adult spinal deformity with long spinal fusion from T9/T10 to the ilium.

Proximal junctional kyphosis (PJK) is a common complication after corrective long spinal fusion for adult spinal deformity. Although some reports evaluated PJK after corrective long spinal fusion, there is no report about analysis of PJK cases in the same fusion area. The purpose of this study to investigated the incidence of and risk factors for PJK in adults undergoing long spinal fusion from the distal thoracic vertebrae (T9/T10) to the ilium. We enrolled 56 adult patients (>40 years of age) who underwent posterior corrective surgery with same fusion area from T9 or T10 to the ilium for spinal deformity. Pre- and postoperative radiographic measurements included the sagittal vertical axis (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic tilt (PT), and pelvic incidence minus LL (PI-LL). The Oswestry disability index (ODI) was used to evaluate patient outcomes preoperatively and one year after surgery. We analyzed the incidence for PJK and compared PJK and non-PJK cases. PJK at the final follow-up occurred in 19 of 56 (33.9%) patients. The mean age and ODI were not significantly different between the PJK and non-PJK groups. Both two groups had good spinopelvic sagittal alignment after surgery in terms of SVA and PI-LL. Only three cases required revision surgery for symptomatic PJK. Three cases had history of rheumatoid arthritis and/or total hip arthroplasty surgery. The incidence of PJK was 33.9%, and ODI was not significantly different between the PJK and non-PJK groups. Symptomatic PJK was only three cases and all of them had lower extremity joint disorders. We should pay attention also lower extremity joint to prevent symptomatic PJK at the lower thoracic level.

Patients with proximal junctional kyphosis after stopping at thoracolumbar junction have lower muscularity, fatty degeneration at the thoracolumbar area

Background ContextThere are several reports regarding pathogeneses and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity surgery. However, the relationship between thoracolumbar muscle condition and PJK has not been investigated yet. PurposeWe aimed to elucidate the thoracolumbar muscle conditions on the incidence of PJK in adult patients with spinal deformity treated by long instrumented spinal fusion surgery stopping at thoracolumbar junction with a minimum 2-year follow-up (F/U). Study DesignThis is a retrospective review of prospective database. Patient SampleA total of 44 cases of patients having multilevel spinal instrumented fusion stopping at thoracolumbar junction for adult spinal deformity in two academic institutions from 2004 to 2012 were enrolled in this study. Outcome MeasuresFor clinical outcomes, the Scoliosis Research Society questionnaire-22r (SRS-22r) was used preoperatively and at ultimate F/U. MethodsInclusion criteria were age >20 and minimum five vertebrae fused from T9 upper instrumented vertebra (UIV) to any lower instrumented vertebra. Radiographic assessment included pelvic parameters, Cobb measurements in the coronal-sagittal plane, and measurements of the thoracolumbar muscularity (cross-sectional area of muscle-vertebral body ratio×100) and fatty degeneration (signal intensity of muscle-subcutaneous fat ratio×100). ResultsThe prevalence of PJK was 38.6%. Age at surgery, gender, fusions extending to the sacrum, levels fused, combined anterior-posterior surgery, and a UIV level were not significantly different between PJK and non-PJK groups. Lower bone mineral density (BMD; T-score: −2.5 vs. −1.3, p=.003) and lower muscularity and higher fatty degeneration at the level of T10 to L2 (131.8 vs. 159.0, p<.01; 59.0 vs. 44.0, p<.001, respectively) were identified risk factors for PJK. Radiographic parameters demonstrated a higher postoperative lumbar lordosis (LL) change (43.8 vs. 29.3, p<.001) and a larger sagittal vertical axis (SVA) change with surgery (8.4 cm vs. 4.8 cm, p=.01) in those with PJK. Although SRS postop pain scores were inferior in PJK group (3.3 vs. 4.1, p<.05), there were no significant differences in the average scores between the groups (3.5 vs. 3.3, p<.05). ConclusionsPatients with PJK had lower thoracolumbar muscularity and higher fatty degeneration than patients without PJK before surgery. Our data suggest that osteoporosis, large corrections in LL and SVA with surgery, and lower muscularity and higher fatty degeneration at the thoracolumbar area can lead to PJK.

Proximal Junctional Kyphosis Results in Inferior SRS Pain Subscores in Adult Deformity Patients

Retrospective comparative study. We aimed to examine the difference in clinical outcomes in proximal junctional kyphosis (PJK). To date, PJK has been primarily a radiographical finding. Inferior outcomes associated with PJK have not been reported. We performed an analysis of PJK in adult deformity patients to identify risk factors and to evaluate clinical outcomes. A total of 364 patients at a single institution from 2002 to 2007 with adult scoliosis, with an average 3.5 years' follow-up were analyzed. Inclusion criteria were age more than 18 years and fusion greater than 5 levels from any thoracic upper instrumented vertebrae to any lower instrumented vertebrae. Cobb measurements in the coronal and sagittal plane in addition to measurements of the PJK angle at postoperative time points were performed. Clinical assessment was performed using Scoliosis Research Society (SRS) scores and the Oswestry Disability Index. The prevalence of PJK was 39.5% (144/364). The average age in the non-PJK group (n-PJK) was 48.9 versus 53.3 in the PJK group (PJK), and, specifically, age more than 60 years posed a higher prevalence. The prevalence of osteoporosis was 9.8% versus 20.4% in the n-PJK versus PJK groups, respectively. Sex, body mass index, revision surgery, and smoking status were not different between groups. Pain was prevalent in 0.9% versus 29.4% in n-PJK versus PJK, which resulted in lower composite SRS Pain scores (mean change +1.2 vs. +0.8), despite no differences seen in other SRS domains, total SRS score, or Oswestry Disability Index. On multivariate analysis, the presence of pain of the upper back was highly predictive of PJK (odds ratio, 12.5, 95% confidence interval, 2.5-63.2). Radiographically, no differences were seen between groups. However, increasing distance of the upper instrumented vertebrae to C7 plumb line had a higher prevalence of PJK. Instrumentation type, surgical approach, and crosslink use were not different between groups. PJK results in worse clinical outcomes measured by the SRS Pain subscore. Our regression model suggests that pain in the upper back has a strong predictive value for PJK. 3.