Paraspinal muscle degeneration and lower bone mineral density as predictors of proximal junctional kyphosis in elderly patients with degenerative spinal diseases: a propensity score matched case–control analysis
BMC Musculoskeletal Disorders volume 23, Article number: 1010 (2022)
Retrospective case–control study.
Proximal junctional kyphosis (PJK) is a postoperative complication involving the proximal segments which is commonly seen in patients with degenerative spine diseases (DSD). The purpose of the present study was to identify predictive factors for postoperative PJK in elderly patients with DSD.
We reviewed elderly patients with DSD who underwent thoracolumbar fusion involving no less than 3 levels. Patients who developed PJK were propensity score-matched with patients with DSD who received the same procedure but did not develop PJK. Demographic characteristics, sagittal vertical axis (SVA), computed tomography (CT) value (Hounsfield unit), and paraspinal muscle parameters were compared between PJK and non-PJK groups.
Eighty-three PJK and non-PJK patients were selected by propensity score matching for age, sex, history of smoking, body mass index, number of fused segments, and upper instrumented vertebra (UIV) location. SVA showed no significant difference between the two groups. In PJK group, fatty infiltration (FI) in erector spinae and multifidus was significantly greater, while the relative cross-sectional area (rCSA) of erector spinae was significantly smaller than that in non-PJK group. CT value was significantly lower in PJK group. Lower erector spinae rCSA and CT value of the UIV, higher erector spinae FI and multifidus FI were identified as predictors of postoperative PJK.
PJK is a common complication in older patients with DSD. Paraspinal muscle degeneration and low bone mineral density of the UIV are predictors of PJK. Protective measures targeting paraspinal muscles and the UIV may help prevent postoperative PJK.
Population ageing is a global phenomenon that is attributable to the progressive increase in life expectancy over the last few decades. Elderly patients present a range of challenges for clinicians. In our spinal surgery practice, we have noticed an increasing number of patients with degenerative spine diseases (DSD) who opt for surgical intervention rather than conservative treatment due to longer life expectancy and improved surgical outcomes. Elderly patients with DSD are at a higher risk of complications, complicated comorbidities, and lower compensatory capacity. As elderly patients tend to have reduced bone mineral density (BMD) and greater degree of spinal imbalance, postoperative mechanical complications have become a major concern . Proximal junctional kyphosis (PJK) is a postoperative complication involving the proximal segments that is commonly seen in surgically-treated DSD cases . Glattes et al. first defined PJK as a proximal junctional sagittal Cobb angle between the lower endplate of upper instrumented vertebra (UIV) and the upper endplate of 2 supra-adjacent vertebrae ≥ 10° and at least 10° greater than the preoperative measurement . PJK results in poor surgical outcomes due to pain, deformity, instability, disability, and potential neurologic deficits. The reported incidence of PJK ranges from 5 to 46%, with two-thirds of cases occurring within 3 months after surgery and 80% of cases occurring within 18 months after surgery .
Of late, much attention has been paid to prevent PJK and achieve satisfactory outcomes. Previous studies indicated that age, BMD, numbers of fused segments, and UIV location are risk factors for postoperative PJK in patients with DSD [4,5,6,7,8,9,10,11,12,13]. Recently the role of paraspinal muscles in the process of spinal stability and degenerative changes is increasingly being recognized. As a spinal stabilizer and an effector for maintaining sagittal balance, the function of the paraspinal muscles affects the risk of postoperative mechanical complications [4, 14]. However, PJK in elderly DSD patients is a multi-factorial postoperative complication. A variety of factors, including age-related comorbidities and degenerative changes, surgical approach and procedures makes it difficult to distinguish the effects of anatomic factors on UIV. For elderly patients with long segments fusion, the influence of anatomic factors on the occurrence of postoperative PJK remains unclear. Therefore, we aimed to identify predictive factors for postoperative PJK in elderly patients with DSD. We hypothesized that elderly DSD patients with paraspinal muscle degeneration and reduced BMD at UIV have a higher incidence of postoperative PJK.
This study was approved by the Ethics Committee of the Xuanwu hospital, Capital Medical University. The patient hospitalization number were used to encode demographic information and surgical data of the subjects. All parties were fully aware of the confidentiality requirements under the Helsinki Declaration. The requirement for written informed consent of patients was waived off by the Ethics Committee of Xuanwu hospital as this was a retrospective study.
We retrospectively reviewed elderly patients (age > 65 years) with DSD who were diagnosed and treated at our center between January 2016 and December 2019. Patients with DSD who underwent thoracolumbar fusion with fusion of no less than 3 levels were eligible for inclusion. The exclusion criteria were: neuromuscular diseases, spinal infection, ankylosing spondylitis, spinal tumor, and previous spinal trauma or surgery. We also excluded patients who underwent minimally invasive lumbar fusion surgery and patients with cement-augmented pedicle screws.
Radiological PJK was defined as a sagittal Cobb angle between the UIV and the two levels above the UIV (UIV + 2) of ≥ 10° and at least 10° greater than the preoperative measurement . According to the diagnostic criteria, a total of 108 patients with postoperative PJK were screened out. As a control group, 225 DSD patients who received the same procedure without PJK were selected by propensity score matching for age, sex, history of smoking, BMI, number of fused segments, and UIV location (lower thoracic spine or upper lumbar spine).
The image data of all patients were collected and measured using the hospital's built-in Picture Archiving and Communication System (PACS). All patients underwent preoperative full spine standing x-ray, computed tomography (CT), and magnetic resonance imaging (MRI) of the corresponding spinal area. Postoperative full spine standing x-ray was obtained during the follow-up period at the time points of 1, 3, 6, 12, 24, and 36 months. A minimum of 18-month follow-up was required.
Posterior surgery consisted of a standard posterior midline approach with implementation of a bilateral pedicle screws and rods system. Decompression of the spine was then carried out using laminectomy or foraminotomy with complete decompression of the central canal and the lateral recesses. Laminae, transverse processes, and facet joints were thoroughly decorticated to expose adequate bleeding bony surfaces for interlaminar and intertransverse fusion.
The paraspinal muscle cross-sectional area (CSA) measurement was made in the middle layer of the MRI on L1/L2 segment using the gray-scale discrimination method proposed by Ranson et al. . CSA of erector spinae (ES) and multifidus muscle (MF) was obtained by dividing the region of interest (ROI) according to the boundaries of each paraspinal muscle on the cross section. Relative cross-sectional area (rCSA) was adopted to eliminate the individual differences in muscle volume that may affect the results . rCSA is the ratio of the paraspinal muscle CSA to the CSA of the vertebra body of the same segment. The mean value of both sides was measured and adopted for analysis. To measure the degree of fatty infiltration (FI) in paraspinal muscles, we defined the middle layer of the MR image as the measurement plane of the segment, and used the threshold method on Image J (National Institutes of Health, Bethesda, MD, USA). Namely, the percentage of the number of fat pixels in the total number of pixels in each paraspinal muscle ROI . A threshold gray-scale value of 120 was used to distinguish the pixels of intramuscular fatty tissue . The measurement method is illustrated in Fig. 1. Sagittal vertical axis (SVA) was measured on preoperative full spine standing x-ray.
The CT HU value of upper instrumented vertebra was measured on preoperative thoracic/lumbar CT scans by dividing the ROI on three layers of axial images of the vertebra body. Average HU value of three ROIs was used to represent the BMD of the UIV [19, 20].
All parameters were separately measured by two orthopedic surgeons with specialized training in radiographic measurement. The mean value of the two measurements was adopted for analysis.
Statistical analysis was conducted using SPSS 26.0 (IBM Corp., USA). Continuous variables are presented as mean ± standard deviation. Parameters of PJK patients were compared with the propensity-score matched control group using student t test and Chi-squared test. Receiver operating characteristic (ROC) curves were constructed for SVA, paraspinal muscles parameters, and CT HU value of the UIV. The optimal cutoff values to differentiate between patients with PJK and control patients were determined. Intra-observer reliability and the inter-observer reliability were evaluated using the intraclass correlation coefficient (ICC) . ICCs less than ± 0.40 indicate poor, ± 0.40–0.75 indicate fair or good, and ± 0.75–1.00 indicate excellent reliability . P values < 0.05 were considered indicative of statistical significance.
A total of 1832 patients undergoing posterior lumbar fusion were examined, of which 333 patients qualified the inclusion criteria and had obtained sufficient follow-up. The prevalence of PJK was 32.4% (n = 108) and the average follow-up was 24.2 months (range 18–46). Among them, 83 PJK and non-PJK patients were selected by propensity score matching for age, sex, history of smoking, BMI, number of fused segments, and UIV location. Unmatched and matched parameters are summarized in Tables 1 and 2.
We compared preoperative SVA, CT HU value, and muscle parameters between PJK patients and propensity score matched cohort of non-PJK patients. SVA showed no significant difference between the two groups. Paraspinal muscle parameters were found significantly different between PJK and non-PJK patients. ES and MF FI of PJK patients were significantly greater, while the ES rCSA was significantly smaller compared to the non-PJK group. CT HU value of the UIV was significantly lower in the PJK group. On combining the rCSA of ES and MF, the PJK group showed significantly smaller extensor muscle rCSA compared to non-PJK patients. There was excellent intra-observer and inter-observer reliability with respect to measurements for muscle rCSA and FI (ICCs > 0.8). The preoperative parameters are summarized in Table 3.
On ROC curve analysis, the optimal ES rCSA cut-off value of 12.17 cm2 was associated with 62.7% sensitivity and 63.9% specificity for the diagnosis of PJK [AUC: 0.624 (95% CI, 0.539–0.709)]. The optimal cut-off value of CT HU value of UIV was 120.87, which was associated with 50.6% sensitivity and 78.3% specificity for the diagnosis of PJK [AUC: 0.646 (95% CI, 0.562–0.730)]. The optimal ES FI cut-off value of 47.90% was associated with 51.8% sensitivity and 74.7% specificity for the diagnosis of PJK [AUC: 0.628 (95% CI, 0.542–0.713)]. The optimal MF FI cut-off value of 58.03% was associated with 65.1% sensitivity and 80.7% specificity for the diagnosis of PJK [AUC: 0.732 (95% CI, 0.654–0.809)]. The ROC curves of the above-mentioned parameters are presented in Figs. 2,3,4, and 5.
PJK is a commonly encountered complication of internal fixation after surgical intervention for DSDs. Several risk factors for PJK have been identified in the contemporary literature [4, 6,7,8, 23]. In the present study, greater FI of MF and ES, lower rCSA of ES and CT HU value of the UIV were related to postoperative PJK, with cut-off values of 58.03%, 47.90%, 12.17 cm2, and 120.87, respectively. Typical cases of PJK and non-PJK group were presented in Figs. 6 and 7.
Surgical, radiological and patient-related factors have all been implicated in the occurrence of PJK [9,10,11, 24,25,26,27,28]. Greater age at surgery and larger BMI are proven risk factors for PJK [6, 11, 23, 28]. Compared to younger individuals, elderly patients often have lower BMD, lesser muscle mass, and may require more aggressive spinal correction. These factors make elderly patients vulnerable to postoperative PJK. Therefore, spine surgeons should pay special attention to the prevention of PJK in elderly patients. Some instrumentation techniques such as hook or hybrid instrumentation may lead to lower incidence of PJK compared to the use of pedicle screws in the upper instrumented level [24, 29,30,31]. In the present study, pedicle screw fixation was applied in all cases by the same surgical team. Many studies have shown that the selection of UIV may affect the incidence of PJK [6, 12, 13, 32]. By conducting propensity score matching of cases, the present study aimed to minimize the impact of age, sex, BMI, and surgical factors on the incidence of PJK.
The mechanism of PJK can be divided into osseous failure of the vertebrae and posterior ligamentous complex failure. As a subtype of PJK, Hart et al. initially defined proximal junctional failure (PJF) as acute fracture and collapse of proximal junctional structure . Yagi et al. divided PJK into 3 types: PJK from disc and ligamentous failure as type 1, bone failure as type 2, implant/bone interface failure as type 3 . Their first type corresponds to posterior ligamentous complex failure and the second and third types are vertebrae osseous failure. Therefore, the predictive factors and preventive measures of PJK can be summarized into these two major categories.
The present study demonstrated the relation between degeneration of paraspinal muscles and PJK. PJK patient group showed lower rCSA and higher FI of both MF and ES. These result are consistent with those of previous studies [4, 27, 34]. Paraspinal muscle degeneration presents as atrophy and fatty infiltration [35, 36]. In the present study, greater FI of MF and ES, and lower rCSA of ES were related to postoperative PJK. These results indicated that paraspinal muscle degeneration is an independent risk factor for postoperative PJK. As an important stabilizer of the spine, the paraspinal muscles play an important role in the degenerative process of the spine. Fully functional paraspinal muscles help maintain the stability of the spine and slow the progression of spinal degeneration. Several recent studies have shown an equally important role of the paraspinal muscles as a stabilizer after spinal fusion [14, 27, 34]. Functional paraspinal muscles can provide protection and reduce the mechanical stress on the proximal segments, thereby reducing the risk of postoperative PJK . Paraspinal muscle degeneration is commonly seen in DSD patients. Therefore, paraspinal muscle assessment should be incorporated into routine preoperative planning.
Moreover, surgical exposure of the spine can also cause damage to the paraspinal muscles. Mechanical instability caused by soft-tissue disruption is concentrated at the proximal junction, causing damage to the UIV and adjacent segments . At the same time, postoperative PJK disrupts the integrity and stability of the proximal junctional biomechanical structure. These changes may lead to further paraspinal muscle degeneration. Therefore postoperative paraspinal muscles degeneration and PJK can be mutually causal, and further longitudinal studies are required to clarify the causal relationship. For DSD patients with severe paraspinal muscle degeneration, compensatory protective measures should be implemented with respect to the selection of UIV, the type of internal fixation, and the enhancement techniques. Francisco et al. introduced a new strap enhancement technique applied in posterior spinal fusion which showed a protective effect against PJK . Intra-operative measures such as conscious preservation of the paraspinal muscles and augmentation of the posterior ligamentous complex have also been shown to prevent PJK.
The results of the present study showed that lumbar spine BMD (CT HU value of lumbar vertebrae) is related to the occurrence of PJK. The CT value of vertebrae in PJK group was significantly lower than those in the non-PJK group. The bone quality of the proximal segments, especially the UIV and UIV + 1, is an important determinant of the stability of the internal fixation including pedicle screws [39, 40]. In recent studies, lower Hounsfield units at the UIV and UIV + 1 showed a significant association with PJK and PJF [41, 42]. Degenerative bone mass loss is manifested as osteopenia and osteoporosis, which are commonly seen in DSD patients [43, 44]. These conditions should be thoroughly assessed and considered during the preoperative planning process. Recently, several preventive measures have been proposed to reduce the risk of PJK. The use of bisphosphonates or biosynthetic parathyroid hormone in combination with calcium and vitamin D is effective in maintaining bone mass in elderly patients . Regular anti-osteoporosis therapy may have important implications for preventing fixation-related complications including PJK, especially in elderly patients. In addition, augmentation techniques such as vertebroplasty at UIV and UIV + 1 have been shown to be a protective factor .
Targeted surgical strategies and techniques need to be applied in elderly patients to obtain satisfactory clinical outcomes. Owing to the progressive population aging, elderly patients account for an increasing proportion of the DSD patient population. Surgical intervention in elderly DSD patients poses complex challenges. Elderly DSD patients are at higher risk of developing paraspinal muscle degeneration and osteoporosis than younger patients. The presence of these degenerative factors increases the risk of mechanical complications, including PJK. Previous studies have suggested that surgical intervention in elderly DSD patients requires age-based strategies including preoperative planning, the use of “soft landing” with hooks instead of pedicle screws at the proximal end of the construct, cement augmentation in UIV and UIV + 1, posterior ligamentous complex reinforcement with polyethelyene tether, and protection of paraspinal muscles [12, 30, 46, 47].
Some limitations of our study should be considered while interpreting the results. First, measurement errors in the manual selection of the ROI of the paraspinal muscles cannot be ruled out. However, we minimized the scope for errors by measuring paraspinal FI using a grayscale threshold method. In addition, the measurements were independently performed by two specifically trained orthopedic surgeons, and the mean value of the two measurements was used for analysis. Second, since not all DSD patients had undergone thoracic MRI, we selected L1/L2 level for paraspinal muscle measurements. Although the paraspinal muscle degeneration tends to be consistent among different levels, the L1/L2 level parameters may not be entirely representative of the condition of paraspinal muscles in other UIV segments . Future studies should include assessment of the entire lumbar paraspinal muscles. Lastly, we measured muscle parameters including rCSA and FI to assess muscle degeneration. However, there is no clear consensus whether radiological parameters are sufficiently representative of muscle function [35, 36]. Use of electromyography and muscle strength measurements can help provide more robust evaluation.
PJK is a common complication in older patients with DSD. Paraspinal muscle degeneration and low bone mineral density of the UIV are predictors of PJK. Protective measures targeting paraspinal muscles and the UIV may play a key role in preventing postoperative PJK.
Availability of data and materials
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.
Degenerative spine diseases
Bone mineral density
Proximal junctional kyphosis
Upper instrumented vertebra
Region of interest
Relative cross-sectional area
Sagittal vertical axis
Intraclass correlation coefficient
Proximal junctional failure
Acosta FL, Jr., McClendon J Jr Fau - O'Shaughnessy BA, O'Shaughnessy Ba Fau - Koller H, Koller H Fau - Neal CJ, Neal Cj Fau - Meier O, Meier O Fau - Ames CP, Ames Cp Fau - Koski TR, Koski Tr Fau - Ondra SL, Ondra SL: Morbidity and mortality after spinal deformity surgery in patients 75 years and older: complications and predictive factors. (1547–5646 (Electronic)).
Kim JS, Phan K, Cheung ZB, Lee N, Vargas L, Arvind V, Merrill RK, Gidumal S, Di Capua J, Overley S, et al. Surgical, radiographic, and patient-related risk factors for proximal junctional kyphosis: a meta-analysis. Global Spine J. 2019;9(1):32–40.
Glattes RC, Bridwell Kh Fau - Lenke LG, Lenke Lg Fau - Kim YJ, Kim Yj Fau - Rinella A, Rinella A Fau - Edwards C, 2nd, Edwards C, 2nd, Yagi M, Akilah Kb Fau - Boachie-Adjei O, Boachie-Adjei O: Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion: incidence, outcomes, and risk factor analysis Incidence, risk factors and classification of proximal junctional kyphosis: surgical outcomes review of adult idiopathic scoliosis. (1528–1159 (Electronic)).
Kim YJ, Bridwell KH, Lenke LG, Glattes CR, Rhim S, Cheh G. Proximal junctional kyphosis in adult spinal deformity after segmental posterior spinal instrumentation and fusion: minimum five-year follow-up. Spine (Phila Pa 1976). 2008;33(20):2179–84.
Kim HJ, Bridwell KH, Lenke LG, Park MS, Song KS, Piyaskulkaew C, Chuntarapas T. Patients with proximal junctional kyphosis requiring revision surgery have higher postoperative lumbar lordosis and larger sagittal balance corrections. Spine (Phila Pa 1976). 2014;39(9):E576-580.
Bridwell KH, Lenke LG, Cho SK, Pahys JM, Zebala LP, Dorward IG, Cho W, Baldus C, Hill BW, Kang MM. Proximal junctional kyphosis in primary adult deformity surgery: evaluation of 20 degrees as a critical angle. Neurosurgery. 2013;72(6):899–906.
O’Leary PT, Bridwell KH, Lenke LG, Good CR, Pichelmann MA, Buchowski JM, Kim YJ, Flynn J. Risk factors and outcomes for catastrophic failures at the top of long pedicle screw constructs a matched cohort analysis performed at a single center. Spine. 2009;34(20):2134–9.
Sebaaly A, Sylvestre C, El Quehtani Y, Riouallon G, Larrieu D, Boissiere L, Steib JP, Roussouly P, Wolff S, Obeid I: Incidence and Risk Factors for Proximal Junctional Kyphosis: Results of a Multicentric Study of Adult Scoliosis. (2380–0194 (Electronic)).
Yagi M, Fujita N, Tsuji O, Nagoshi N, Asazuma T, Ishii K, Nakamura M, Matsumoto M, Watanabe K. Low bone-mineral density is a significant risk for proximal junctional failure after surgical correction of adult spinal deformity. Spine. 2018;43(7):485–91.
Park SJ, Lee CS, Chung SS, Lee JY, Kang SS, Park SH. Different risk factors of proximal junctional kyphosis and proximal junctional failure following long instrumented fusion to the sacrum for adult spinal deformity: survivorship analysis of 160 patients. Neurosurgery. 2017;80(2):279–86.
Yagi M, King AB, Boachie-Adjei O. Incidence, risk factors, and natural course of proximal junctional kyphosis: surgical outcomes review of adult idiopathic scoliosis. minimum 5 years of follow-up. Spine (Phila Pa 1976) 2012;37(17):1479–89.
Maruo K, Ha Y, Inoue S, Samuel S, Okada E, Hu SS, Deviren V, Burch S, William S, Ames CP, et al. Predictive factors for proximal junctional kyphosis in long fusions to the sacrum in adult spinal deformity. Spine (Phila Pa 1976). 2013;38(23):E1469-1476.
Hostin R, McCarthy I, O’Brien M, Bess S, Line B, Boachie-Adjei O, Burton D, Gupta M, Ames C, Deviren V, et al. Incidence, mode, and location of acute proximal junctional failures after surgical treatment of adult spinal deformity. Spine (Phila Pa 1976). 2013;38(12):1008–15.
Choi UY, Kang JI, Park JY, Kuh SU, Chin DK, Kim KS, Cho YE, Kim KH. Residence could influence the surgical outcome after corrective surgery in adult spinal deformity: comparison study between urban and rural area in Korea. Eur Spine J. 2019;28(9):2216–22.
Ranson CA, Burnett AF, Kerslake R, Batt ME, O’Sullivan PB. An investigation into the use of MR imaging to determine the functional cross sectional area of lumbar paraspinal muscles. Eur Spine J. 2006;15(6):764–73.
Urrutia J, Besa P, Lobos D, Campos M, Arrieta C, Andia M, Uribe S. Lumbar paraspinal muscle fat infiltration is independently associated with sex, age, and inter-vertebral disc degeneration in symptomatic patients. Skeletal Radiol. 2018;47(7):955–61.
Lee JC, Cha Jg Fau - Kim Y, Kim Y Fau - Kim Y-I, Kim Yi Fau - Shin B-J, Shin BJ: Quantitative analysis of back muscle degeneration in the patients with the degenerative lumbar flat back using a digital image analysis: comparison with the normal controls. (1528–1159 (Electronic)).
Kim H, Lee CK, Yeom JS, Lee JH, Cho JH, Shin SI, Lee HJ, Chang BS. Asymmetry of the cross-sectional area of paravertebral and psoas muscle in patients with degenerative scoliosis. Eur Spine J. 2013;22(6):1332–8.
Choi MK, Kim SM, Lim JK: Diagnostic efficacy of Hounsfield units in spine CT for the assessment of real bone mineral density of degenerative spine: correlation study between T-scores determined by DEXA scan and Hounsfield units from CT. (0942–0940 (Electronic)).
Zou D, Li WS, Deng C, Du GH, Xu NF. The use of CT Hounsfield unit values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases. Eur Spine J. 2019;28(8):1758–66.
Chen RQ, Hosogane N, Watanabe K, Funao H, Okada E, Fujita N, Hikata T, Iwanami A, Tsuji T, Ishii K, et al. Reliability analysis of spino-pelvic parameters in adult spinal deformity: a comparison of whole spine and pelvic radiographs. Spine. 2016;41(4):320–7.
Dang NR, Moreau MJ, Hill DL, Mahood JK, Raso J. Intra-observer reproducibility and interobserver reliability of the radiographic parameters in the spinal deformity study group’s AIS radiographic measurement manual. Spine (Phila Pa 1976). 2005;30(9):1064–9.
Kim HJ, Bridwell KH, Lenke LG, Park MS, Song KS, Piyaskulkaew C, Chuntarapas T. Patients with proximal junctional kyphosis requiring revision surgery have higher postoperative lumbar lordosis and larger sagittal balance corrections. Spine. 2014;39(9):E576–80.
Wang T, Zhao Y, Liang Y, Zhang H, Wang Z, Wang Y. Risk factor analysis of proximal junctional kyphosis after posterior osteotomy in patients with ankylosing spondylitis. J Neurosurg Spine. 2018;29(1):75–80.
Yagi M, Akilah KB, Boachie-Adjei O. Incidence, risk factors and classification of proximal junctional kyphosis. Spine. 2011;36(1):E60–8.
Ferrero E, Bocahut N, Lefevre Y, Roussouly P, Pesenti S, Lakhal W, Odent T, Morin C, Clement JL, Compagnon R, et al. Proximal junctional kyphosis in thoracic adolescent idiopathic scoliosis: risk factors and compensatory mechanisms in a multicenter national cohort. Eur Spine J. 2018;27(9):2241–50.
Pennington Z, Cottrill E, Ahmed AK, Passias P, Protopsaltis T, Neuman B, Kebaish KM, Ehresman J, Westbroek EM, Goodwin ML, et al. Paraspinal muscle size as an independent risk factor for proximal junctional kyphosis in patients undergoing thoracolumbar fusion. J Neurosurg Spine. 2019;31(3):380–8.
Sebaaly A, Sylvestre C, El Quehtani Y, Riouallon G, Larrieu D, Boissiere L, Steib JP, Roussouly P, Wolff S, Obeid I. Incidence and risk factors for proximal junctional kyphosis: results of a multicentric study of adult scoliosis. Clin Spine Surg. 2018;31(3):E178–83.
Cammarata M, Aubin CE, Wang X, Mac-Thiong JM. Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables. Spine (Phila Pa 1976). 2014;39(8):E500-507.
Hassanzadeh H, Gupta S, Jain A, El Dafrawy MH, Skolasky RL, Kebaish KM: Type of Anchor at the Proximal Fusion Level Has a Significant Effect on the Incidence of Proximal Junctional Kyphosis and Outcome in Adults After Long Posterior Spinal Fusion. (2212–1358 (Electronic)).
Helgeson MD, Shah SA, Newton PO, Clements DH, 3rd, Betz RR, Marks MC, Bastrom T, Harms Study G. Evaluation of proximal junctional kyphosis in adolescent idiopathic scoliosis following pedicle screw, hook, or hybrid instrumentation. Spine (Phila Pa 1976). 2010;35(2):177–81.
OʼShaughnessy BA, Bridwell Kh Fau - Lenke LG, Lenke Lg Fau - Cho W, Cho W Fau - Baldus C, Baldus C Fau - Chang MS, Chang Ms Fau - Auerbach JD, Auerbach Jd Fau - Crawford CH, Crawford CH: Does a long-fusion "T3-sacrum" portend a worse outcome than a short-fusion "T10-sacrum" in primary surgery for adult scoliosis? (1528–1159 (Electronic)).
Hart RA, Prendergast MA, Roberts WG, Nesbit GM, Barnwell SL. Proximal junctional acute collapse cranial to multi-level lumbar fusion: a cost analysis of prophylactic vertebral augmentation. The Spine Journal. 2008;8(6):875–81.
Kim DK, Kim JY, Kim DY, Rhim SC, Yoon SH. Risk factors of proximal junctional kyphosis after multilevel fusion surgery: more than 2 years follow-up data. Journal of Korean Neurosurgical Society. 2017;60(2):174–80.
Honkanen T, Mäntysaari M, Leino T, Avela J, Kerttula L, Haapamäki V, Kyröläinen H: Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots: a 5-year follow-up. (1471–2474 (Electronic)).
Schlaeger SA-O, Inhuber S, Rohrmeier A, Dieckmeyer M, Freitag F, Klupp E, Weidlich D, Feuerriegel G, Kreuzpointner F, Schwirtz A et al: Association of paraspinal muscle water-fat MRI-based measurements with isometric strength measurements. (1432–1084 (Electronic)).
Bess S, Harris JE, Turner AW, LaFage V, Smith JS, Shaffrey CI, Schwab FJ, Haid RW Jr. The effect of posterior polyester tethers on the biomechanics of proximal junctional kyphosis: a finite element analysis. J Neurosurg Spine. 2017;26(1):125–33.
F Rodriguez-Fontan BJ Reeves A Noshchenko D Ou-Yang CJ Kleck C Cain 2020 Burger-Van der Walt E, Patel VV: Strap stabilization for proximal junctional kyphosis prevention in instrumented posterior spinal fusion Eur Spine J 29 6 1287 1296
Maruo K, Ha Y Fau - Inoue S, Inoue S Fau - Samuel S, Samuel S Fau - Okada E, Okada E Fau - Hu SS, Hu Ss Fau - Deviren V, Deviren V Fau - Burch S, Burch S Fau - William S, William S Fau - Ames CP, Ames Cp Fau - Mummaneni PV et al: Predictive factors for proximal junctional kyphosis in long fusions to the sacrum in adult spinal deformity. (1528–1159 (Electronic)).
Nicholls FH, Bae J, Theologis AA, Eksi MS, Ames CP, Berven SH, Burch S, Tay BK, Deviren V. Factors associated with the development of and revision for proximal junctional kyphosis in 440 consecutive adult spinal deformity patients. Spine (Phila Pa 1976). 2017;42(22):1693–8.
Mikula AL, Fogelson JL, Lakomkin N, Flanigan PM, Pinter ZW, Doan MK, Bydon M, Nassr A, Freedman B, Sebastian AS et al: Lower Hounsfield Units at the Upper Instrumented Vertebrae are Significantly Associated With Proximal Junctional Kyphosis and Failure Near the Thoracolumbar Junction. LID - opab236 [pii] LID - https://doi.org/10.1093/ons/opab236 [doi]. (2332–4260 (Electronic)).
Duan PG, Mummaneni PV, Rivera J, Guinn JMV, Wang M, Xi Z, Li B, Wu HH, Ames CP, Burch S et al: The association between lower Hounsfield units of the upper instrumented vertebra and proximal junctional kyphosis in adult spinal deformity surgery with a minimum 2-year follow-up. (1092–0684 (Electronic)).
Tomé-Bermejo F, Piñera AR, Alvarez-Galovich L: Osteoporosis and the Management of Spinal Degenerative Disease (I). (2345–4644 (Print)).
Zou D, Jiang S Fau - Zhou S, Zhou S Fau - Sun Z, Sun Z Fau - Zhong W, Zhong W Fau - Du G, Du G Fau - Li W, Li W: Prevalence of Osteoporosis in Patients Undergoing Lumbar Fusion for Lumbar Degenerative Diseases: A Combination of DXA and Hounsfield Units. (1528–1159 (Electronic)).
Vandenbroucke A, Luyten FP, Flamaing J, Gielen E: Pharmacological treatment of osteoporosis in the oldest old. Clin Interv Aging 2017, 12(1178–1998 (Electronic)):1065–1077.
Kebaish KM, Martin Ct Fau - O'Brien JR, O'Brien Jr Fau - LaMotta IE, LaMotta Ie Fau - Voros GD, Voros Gd Fau - Belkoff SM, Belkoff SM: Use of vertebroplasty to prevent proximal junctional fractures in adult deformity surgery: a biomechanical cadaveric study. (1878–1632 (Electronic)).
Rodriguez-Fontan FA-O, Reeves BJ, Noshchenko A, Ou-Yang D, Kleck CJ, Cain C, Burger-Van der Walt E, Patel VV: Strap stabilization for proximal junctional kyphosis prevention in instrumented posterior spinal fusion. (1432–0932 (Electronic)).
Urrutia J, Besa P, Lobos D, Andia M, Arrieta C, Uribe S: Is a single-level measurement of paraspinal muscle fat infiltration and cross-sectional area representative of the entire lumbar spine? (1432–2161 (Electronic)).
This subject was funded by Beijing Municipal Medical Science Institute-Public Welfare Development Reform Pilot Project:(Capital Medical Research No. 2019–2).
Ethics approval and consent to participate
This study has been approved by the Ethics Committee of Xuanwu hospital, Capital Medical University, China. All parties are fully aware of the confidentiality of the Helsinki Declaration. The informed consent was waived by the Ethics Committee of Xuanwu hospital as this was a retrospective study. All methods were carried out in accordance with relevant guidelines and regulations.
Consent for publication
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhang, Tt., Ding, Jz., Kong, C. et al. Paraspinal muscle degeneration and lower bone mineral density as predictors of proximal junctional kyphosis in elderly patients with degenerative spinal diseases: a propensity score matched case–control analysis. BMC Musculoskelet Disord 23, 1010 (2022). https://doi.org/10.1186/s12891-022-05960-z