Osteoporosis and Proximal Junctional Failure in Spinal Surgery
Osteoporosis is a Risk Factor for Proximal Junctional Failure Following Long Spinal Fusion for Adult Spinal Deformity
Sarthak Mohanty, MD¹, Anmol Gupta, MD, MBA¹, Harold Fogel, MD¹, Daniel Tobert, MD¹, Stuart Hershman, MD¹
- Department of Orthopaedics Massachusetts General Hospital, 55 Fruit Street, Boston MA 02114
OPEN ACCESS
PUBLISHED: 31 January 2025
CITATION: Mohanty, S., et al., 2025. Osteoporosis is a Risk Factor for Proximal Junctional Failure Following Long Spinal Fusion for Adult Spinal Deformity. Medical Research Archives, [online] 13(1). https://doi.org/10.18103/mra.v13i1.6199
COPYRIGHT: © 2025 European Society of Medicine. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DOI https://doi.org/10.18103/mra.v13i1.6199
ISSN 2375-1924
ABSTRACT
Background: Bone health has emerged as a critical modifiable risk factor for complications following adult spinal deformity correction. Among these complications, mechanical issues and proximal junctional kyphosis/failure remain particularly challenging, affecting up to 61% and 44% of patients, respectively. We hypothesized that osteoporotic patients undergoing deformity correction experience higher rates of instrumentation failure and proximal junctional kyphosis/failure.
Purpose: To evaluate and compare the complication profiles of osteoporotic and non-osteoporotic patients undergoing long thoracolumbar fusion for adult spinal deformity.
Study Design: Retrospective comparative study
Patient Sample: adult spinal deformity patients who underwent long thoracolumbar spinal fusion (≥7 levels) at two large academic medical centers between 2010 and 2019.
Outcome Measures: The primary outcome was all-cause revision surgery. Secondary outcomes included pseudarthrosis with or without implant failure, proximal junctional kyphosis/failure rates, infection rates, and time to complication occurrence.
Methods: This retrospective, multicenter study analyzed deformity patients undergoing long-segment instrumentation (≥7 levels) with a minimum two-year follow-up. Exclusion criteria included spinal deformity secondary to tumor, infection, trauma, or neuromuscular disorders. Preoperative osteoporosis status was determined using dual-energy X-ray absorptiometry (DXA) T-scores at the hip and femoral neck. The complication profiles of osteoporotic and non-osteoporotic deformity patients were compared using Chi-squared or Fisher’s exact tests for categorical variables and two-tailed t-tests for continuous variables.
Results: Among 399 adult spinal deformity patients, 131 (32.8%) were osteoporotic. Osteoporotic patients were significantly older than their non-osteoporotic counterparts (66.43 (SD: 8.9) vs. 63.51 (SD: 8.9), P = 0.0018). The overall complication rate was significantly higher in osteoporotic patients compared to non-osteoporotic patients (40.5% (n = 53) vs. 28.0% (n = 75), P = 0.0122). Incidences of PJK (35.1% (n = 46) vs. 21.6% (n = 58), P = 0.0040) and PJF (19.8% (n = 26) vs. 6.7% (n = 18), P = 0.0001) were also higher in the osteoporotic group, while rates of construct failure/pseudarthrosis (11.5% vs. 15.7%, P = 0.2578) and infection (4.6% vs. 3.7%, P = 0.6849) showed no significant differences. Time to pseudarthrosis (8.1 vs. 8.3 months, P = 0.4582), infection (4.7 vs. 1.5 months, P = 0.0773), PJF (9.3 vs. 10.1 months, P = 0.7300), and overall time to first complication (8.4 vs. 7.6 months, P = 0.5119) were similar between the groups.
Conclusions: Osteoporotic patients have increased risk of proximal junctional kyphosis and failure compared to non-osteoporotic patients, highlighting the need for preoperative osteoporosis surveillance, optimization, and postoperative monitoring to mitigate complications.
Keywords: adult spinal deformity; scoliosis; osteoporosis; surgical complications; fusions; kyphosis; construct failure; revision
Introduction
With a globally aging population, the prevalence of adult spinal deformity (ASD) is rising. Since 2005, rates as high as 68% have been reported in geriatric patients, affecting quality of life of over 28 million elderly individuals¹˒². The rate of corrective surgery for ASD, aimed at preventing progressive deformity, relieving pain, improving self-image, addressing cardiopulmonary comorbidities, and decompressing neurologic elements³˒⁵, increased by 141% since the early 2000s. This rise was predominantly driven by a 460% rise in the incidence of long-segment deformity correction in the elderly subsegment⁶. Despite advancements in the safety of deformity correction, the complication rate remains formidable with large multicenter studies reporting reoperation rates of 26% to 30%⁷. Of these, mechanical complications and proximal junctional kyphosis (PJK) remain among the most challenging issues, affecting up to 61% and 44% of patients, respectively⁸˒⁹.
The clinical and economic burden of PJK and its more severe form, proximal junctional failure (PJF), is profound, with up to a 50% worsening in SRS self-image and pain scores, frequent severe neurological injuries¹⁰–¹³, and direct costs ranging from $20,000 to $120,000¹⁴˒¹⁵. Consequently, significant research has been directed toward understanding etiology, diagnosis, identifying vulnerable populations, and developing prevention strategies and optimal management approaches for PJK/PJF¹⁶˒¹⁷.
Among modifiable patient traits, bone health has emerged as a pivotal risk factor for PJK. For example, Shen et al. reported significantly higher PJK rates in osteoporotic patients (35.4% vs. 17.5%, P = 0.01)¹⁸, while Yao et al. found a negative correlation between mean Hounsfield units (HU) and PJK angle progression (r = -0.475). In fact, HU values below 120 were associated with nearly sixfold higher PJK risk¹⁹. Highlighting the causal nature of this relationship, patients treated with osteo-anabolic agents exhibited significantly lower PJK rates compared to untreated osteoporotic patients (4.6% vs. 15.2%)²⁰. Beyond PJK and PJF, multiple studies have identified poor bone health as a key driver of adverse perioperative outcomes following ASD surgery. Compared to patients with normal bone density, osteoporotic patients have a twofold higher likelihood of all-cause reoperation²¹˒²². Osteopenic and untreated osteoporotic patients exhibit nearly three times the rate of pseudarthrosis with or without implant failure²³˒²⁴, a 3.20-fold higher likelihood of discharge to rehabilitation facilities²⁵, and fragile postoperative functional patient-reported outcome scores. For example, osteoporotic patients are significantly overrepresented among those experiencing postoperative functional decline and persistent debilitating low back pain²⁶˒²⁷.
Evidently preoperative optimization, risk profiles, and outcomes are markedly distinct for osteoporotic patients undergoing ASD correction. While studies such as Varshneya et al. (2022)²⁸ have highlighted the detrimental effects of osteoporosis on the perioperative course and 90-day healthcare utilization, comprehensive characterization of its long-term impact on ASD complications remains limited. This analysis aimed to characterize the two-year complication profiles of patients with osteoporosis compared to those with normal bone mineral density undergoing ASD correction.
Methods
This retrospective study analyzed patients treated for adult spinal deformity (ASD) at two large academic medical centers between 2010 and 2019. Inclusion criteria included adults over 40 years undergoing long-segment spinal fusion involving more than seven instrumented levels, with at least two years of follow-up. A combination of ICD-10 codes—M41.3X (thoracogenic scoliosis), M41.5X (other secondary scoliosis), M41.8X (other forms of scoliosis), and M41.9X (unspecified scoliosis)—and CPT codes 22843 (posterior segmental instrumentation, 7–12 vertebral segments) and 22844 (posterior segmental instrumentation, 13 or more vertebral segments) was deployed to identify eligible patients.
The analysis comprised patients diagnosed with adult degenerative, idiopathic, or iatrogenic spinal
deformity (ASD) with the primary deformity apex located in the cervicothoracic or thoracolumbar region. Eligible participants met at least one of the following radiographic and/or procedural criteria: pelvic incidence minus lumbar lordosis (PI-LL) ≥20°, T1 Pelvic Angle (TPA) ≥20°, Sagittal Vertical Axis (SVA) ≥4 cm, scoliosis ≥50°, global coronal malalignment ≥4 cm, undergoing a three-column osteotomy, or spinal fusion involving ≥7 levels. Exclusion criteria included those with active spine tumors or infections, spinal deformities secondary to trauma, neuromuscular conditions, syndromic scoliosis, inflammatory or autoimmune diseases, incarceration, pregnancy. All patients underwent posterior spinal fusion (PSF), with the use of 1–2 level (L3-S1) transforaminal lumbar interbody fusions (TLIFs), 24 mg of BMP, and supplemental rods determined at the surgeon’s discretion.
DATA COLLECTION
We collected data on demographic and patient characteristics, bone health, aggregate preoperative health measures, baseline spinal alignment, and surgical characteristics. Preoperative bone health evaluations were performed for patients over 40 years, with osteoporosis status determined by T-scores at the hip and femoral neck. Radiographic assessments were conducted preoperatively and at two years postoperatively using the EOS 2D/3D Imaging System.
OUTCOME MEASURES
The primary outcome was the two-year overall complication rate. Recorded surgical complications included hardware-related failures, pseudarthrosis, hematoma, proximal junctional kyphosis/failure (PJK/F), wound dehiscence, and both superficial and deep infections.
Secondary outcomes included pseudarthrosis with or without implant failure—defined as rod breakage, screw loosening, breakage, pullout, or interbody graft dislodgement—determined through consensus between a radiologist and surgeon using thin-section CT scans. All pseudarthrosis cases were confirmed intraoperatively. Additional secondary outcomes included the PJK rate, defined as a ≥10° increase in kyphosis between the upper instrumented vertebra (UIV) and UIV+2 on follow-up radiographs. The time to reoperation was recorded and stratified into four categories: 0–30 days, 30–90 days, 90 days–2 years, and greater than 2 years postoperatively, with quantitative values ranging from seven to 882 days post-surgery.
STATISTICAL ANALYSIS
The impact of osteoporosis status on clinical outcomes was evaluated by comparing patients with osteoporosis to those with normal bone mineral density (BMD). Categorical variables were analyzed using Chi-Squared or Fisher’s exact tests, while continuous outcomes were assessed with two-tailed t-tests. Statistical significance was defined as P ≤0.05. Analyses were conducted using SAS (SAS 9.4, SAS Institute Inc., Cary, NC, USA) and GraphPad Prism (v8.4.2, GraphPad Software, La Jolla, CA, USA).
Results
The cohort comprised of 399 patients, of whom 131 (32.8%) were classified as osteoporotic and 268 (67.2%) as those with normal bone mineral density. The mean age of the cohort was 64.47 years (SD: 8.8), with osteoporotic patients being significantly older than their non-osteoporotic counterparts (66.43 (SD: 8.9) vs. 63.51 (SD: 8.9), P = 0.0018).
Females comprised 66.2% (n = 264) of the cohort, with a higher prevalence among osteoporotic patients compared to non-osteoporotic patients (74.8% vs. 61.9%, P = 0.0107). The racial distribution was predominantly Caucasian (95%, n = 379), with no significant differences in the distribution of ethnicities between groups (P = 0.4772).
Complication incidence was significantly higher in the osteoporotic group compared to the non-osteoporotic group (40.5% (n = 53) vs. 28.0% (n = 75), P = 0.0122). The prevalence of patients suffering two or more complications was comparable between groups (8.4% vs. 8.6%, P = 0.9504).
Among complications the incidence of PJK was notably higher in the osteoporotic group [35.1%
(n=46) vs. 21.6% (n=58), P=0.0040] with 26.1% (n=104) of all ASD patients experiencing PJK.
Similarly, osteoporotic patients exhibited higher rates of proximal junctional failure (PJF) [19.8% (n=26) vs. 6.7% (n=18), P=0.0001]. However, the incidence of construct failure/pseudarthrosis and infection did not differ significantly between groups [11.5% vs. 15.7%, P=0.2578; 4.6% vs. 3.7%, P=0.6849, respectively]. Complications attributed to other causes were rare in both groups, accounting for 4.6% in osteoporotic and 1.9% in non-osteoporotic patients.
Finally, complications were stratified by time to occurrence and compared within cohorts. Early complications predominantly consisted of infections, occurring on average within the first three months postoperatively. In contrast, pseudarthrosis and related implant failure (mean: 8.3 months) and proximal junctional failure (PJF) (mean: 9.7 months) typically occurred between 8–12 months postoperatively. There were no significant differences in time to pseudarthrosis (8.1 vs. 8.3 months, P = 0.4582), infection (4.7 vs. 1.5 months, P = 0.0773), PJF (9.3 vs. 10.1 months, P = 0.7300), or the overall mean time to the first complication (8.4 vs. 7.6 months, P = 0.5119) between osteoporotic and non-osteoporotic patients.
Discussion
There are three key findings of the present analysis: (1) 26.0% of ASD patients older than 40 years suffered PJK, nearly half of which progressed to PJF requiring reoperation (2) Osteoporotic patients had a significantly higher PJK rate, with a threefold increase in PJF incidence compared to patients without osteoporosis (3) there was no significant difference in the rate of pseudarthrosis or implant failure among patients with osteoporosis.
These benchmarking data are crucial in the context of current clinical practice guidelines, which remain equivocal regarding the preoperative optimization of osteoporotic patients. While Wright et al. reported that 10.3% of Americans over age 50 are osteoporotic²⁹, our findings indicate that the ASD population is disproportionately enriched with osteoporotic patients (33.0%). Kuprys et al. recently reported that preoperative bone health was documented in only 25% of patients undergoing ASD surgery (an increase from 12% in 2012–2014), with fewer than 10% referred to bone health specialists³⁰. DiPaola and Gupta analogously highlight significant gaps in osteoporosis assessment among ASD patients, with only 44% of spine surgeons routinely obtaining DEXA scans, 12% evaluating additional bone health markers, and frequent underdiagnosis due to the limitations of DEXA alone³¹˒³². Similarly, a 2023 clinical practice guideline review concluded that there is fair evidence supporting osteoporosis as a risk factor for perioperative complications in ASD surgery without a recommendation for routine preoperative assessment³³.
The findings presented here highlight that osteoporotic patients face a markedly increased risk of PJK and PJF. A growing body of retrospective cohort studies, all published within the last seven years and limited by small sample sizes, corroborates these findings, consistently demonstrating higher PJK rates among osteoporotic patients³⁴˒³⁵. Similarly, Kim et al.’s 2019 review was the first aggregate study to identify lower BMD as a significant risk factor for PJK (OR: 1.99; 95% CI 1.36–2.92; I² = 0%; P < 0.001), though this conclusion was based on only four studies⁴². More recently, a 2023 meta-analysis reported an aggregate PJK incidence of 24.6% (n = 537), with significantly lower BMD T-scores observed in patients who develop PJK (mean difference: −0.69; 95% CI −0.88 to −0.50; I² = 63.9%; P < 0.001)⁴¹. Additionally, Hounsfield units (HU) at the upper instrumented vertebra (UIV) were significantly lower in the PJK group compared to the non-PJK group⁴¹.
Interestingly, we observed a higher rate of PJF among osteoporotic patients, independent of PJK incidence, with 26/46 (56.5%) osteoporotic patients versus 18/58 (31.0%) non-osteoporotic patients progressing from PJK to PJF, suggesting a potential vulnerability of osteoporotic patients to this
progression. Few studies have explored radiographic progression following PJF development. In 2023, Park et al. identified overcorrection relative to age-adjusted alignment, proximal junctional angle (PJA) at PJF diagnosis, and fractures at the upper instrumented vertebra (UIV) as significant risk factors for PJK-to-PJF progression, though not osteoporosis (33% of progressors had osteoporosis vs. 38% of non-progressors)⁴³. However, the limited number of osteoporotic patients and disparities in post-surgical osteoporosis treatment may have confounded their findings. Conversely, Lee et al., studying risk factors for both PJK and PJF in the same cohort, reported osteoporosis as a risk factor for PJF but not PJK, though their small cohort of 160 patients limits generalizability⁴⁴. Collectively, it remains unclear whether osteoporotic patients are inherently more likely to develop PJK, thereby becoming overrepresented in PJF cohorts, or if PJK patients generally face an elevated risk of progressing to PJF.
Our study counterintuitively found no difference in the prevalence of pseudarthrosis or micromotion-related implant failure between osteoporotic and non-osteoporotic patients²⁴. This finding is surprising given that BMD is known to influence pseudarthrosis risk; osteoporotic spines exhibit 61.1% to 78.9% of the axial pullout force of pedicle screws compared to those with normal BMD⁴⁵˒⁴⁶. Consistently, multiple studies have demonstrated an increased risk of pseudarthrosis and revision surgery in osteoporotic patients following spinal fusion²⁴. Evidence of this, Puvanesarajah et al. reported a twofold increase in the odds of reoperation among osteoporotic patients compared to those with normal BMD²¹˒²²˒⁴⁷.
Taken together, our findings suggest that osteoporotic patients are overrepresented among those undergoing ASD correction and face an increased risk of mechanical complications and progressive postoperative sagittal alignment loss, highlighting the critical importance of preoperative BMD optimization⁴⁸˒⁴⁹ or pharmacologic intervention with osteo-anabolic agents²⁴˒⁵⁰.
Limitations
This study has several limitations. Its retrospective design may introduce indication bias, and the inclusion of only osteoporotic patients with sufficient bone quality for surgery likely introduces selection bias, limiting generalizability. The primarily Caucasian female cohort further restricts applicability to broader populations. Diagnosing pseudarthroses posed challenges, as only symptomatic patients underwent postoperative CT scans, with diagnosis requiring a combination of CT, MRI, and intraoperative validation; thus, the true rate of radiographic non-union may be underreported. Additionally, we did not account for surgeon experience, concomitant medical conditions, the chosen surgical approach, or the relative complexity of the procedures, all of which could unduly influence outcomes. Finally, osteoporosis was analyzed as a categorical variable rather than a continuous one, without accounting for the varying severity of bone density loss within the osteoporotic group.
Conclusion
Osteoporotic patients are enriched among patients undergoing ASD corrective surgery. Patients have increased risk of PJK and PJF compared to non-osteoporotic patients, highlighting the need for preoperative osteoporosis surveillance, optimization, and postoperative monitoring to mitigate complications.
Table 1. Demographic data comparing osteoporotic and non-osteoporotic patients.
| Parameter | Osteoporotic Patients | Non-Osteoporotic Patients | All Patients | p Value |
|---|---|---|---|---|
| Number of Patients | 131 | 268 | 399 | – |
| Age (Mean ± SD) | 66.43 ± 8.9 | 63.51 ± 8.9 | 64.47 ± 8.8 | 0.0018 |
| Sex | 0.0107 | |||
| Male | 33 (25.2%) | 102 (38.1%) | 135 (33.8%) | |
| Female | 98 (74.8%) | 166 (61.9%) | 264 (66.2%) | |
| Race | 379 | 0.4772 | ||
| Caucasian | 121 (92.4%) | 258 (96.3%) | (95.0%) | |
| Black | 2 (1.5%) | 4 (1.5%) | 6 (1.5%) | |
| Asian/Middle Eastern | 3 (2.3%) | 3 (1.1%) | 6 (1.5%) | |
| Other | 3 (2.3%) | 0 (0.0%) | 3 (0.8%) | |
| Unknown | 2 (1.5%) | 3 (1.1%) | 5 (1.3%) |
Comparison of demographic and clinical parameters between osteoporotic, non-osteoporotic, and all patients. Data are presented as counts with percentages in parentheses for categorical variables and as means with standard deviations (SD) for continuous variables. Statistical significance was assessed using appropriate statistical tests, with p-values reported for comparisons between osteoporotic and non-osteoporotic patients. p < 0.05 was considered statistically significant.
Table 2: Overview of revision surgeries among osteoporotic and non-osteoporotic patients.
| Parameter | Osteoporotic (n=131) | Non-Osteoporotic (n=268) | Total (n=399) | p Value |
|---|---|---|---|---|
| Complication Incidence | 53 (40.5%) | 75 (28.0%) | 128 (32.1%) | 0.0122 |
| Multiple Complications | 11 (8.4%) | 23 (8.6%) | 34 (8.5%) | 0.9504 |
| Complication Type | ||||
| Construct Failure/Pseudarthrosis | 15 (11.5%) | 42 (15.7%) | 57 (14.3%) | 0.2578 |
| Infection | 6 (4.6%) | 10 (3.7%) | 16 (4.0%) | 0.6849 |
| PJF | 26 (19.8%) | 18 (6.7%) | 44 (11.0%) | 0.0001 |
| Other Causes | 6 (4.6%) | 5 (1.9%) | 11 (2.8%) | – |
| Total Complications | 53 (40.5%) | 75 (28.0%) | 128 (32.1%) | 0.0122 |
| PJK Incidence | 46 (35.1%) | 58 (21.6%) | 104 (26.1%) | 0.004 |
Comparison of complication incidence, multiple complications, and specific complication types between osteoporotic and non-osteoporotic patients. Data are presented as counts with percentages in parentheses. P-values represent statistical significance for comparisons between osteoporotic and non-osteoporotic groups. P < 0.05 was considered statistically significant.
Table 3: Timing of Revision Surgeries Following Index Surgery.
| Complication Type | Osteoporotic (n=131) | Non-Osteoporotic (n=268) | Total (n=399) | P-Value | |||
|---|---|---|---|---|---|---|---|
| Incidents | Time (Months) | Incidents | Time (Months) | Incidents | Time (Months) | ||
| Construct Failure/Pseudarthrosis | 15 | 8.1 | 42 | 8.3 | 57 | 8.3 | 0.4582 |
| Infection | 6 | 4.7 | 10 | 1.5 | 16 | 2.7 | 0.0773 |
| PJF | 26 | 9.3 | 18 | 10.1 | 44 | 9.7 | 0.73 |
| Other Causes | 6 | 9.1 | 5 | 4.4 | 11 | 6.9 | – |
| TOTAL | 53 | 8.4 | 75 | 7.6 | 128 | 7.9 | 0.5119 |
Timing and incidence of revision surgeries following index surgery in osteoporotic and non-osteoporotic patients, including total cohort data. Data are presented as the number of incidents and the average time in months after index surgery when revision procedures occurred. P-values represent statistical significance for comparisons between osteoporotic and non-osteoporotic groups. P < 0.05 was considered statistically significant.
The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Conflict of Interest:
None
Acknowledgements:
None
References
1. Safaee MM, Ames CP, Smith JS. Epidemiology and Socioeconomic Trends in Adult Spinal Deformity Care. Neurosurgery. 2020;87:25+.
2. Schwab F, Dubey A, Gamez L, et al. Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976). 2005;30(9):1082-1085. doi:10.1097/01.br s.0000160842.43482.cd
3. Koller H, Pfanz C, Meier O, et al. Factors influencing radiographic and clinical outcomes in adult scoliosis surgery: a study of 448 European patients. Eur Spine J. 2016;25(2):532-548. doi:10.1007/s00586-015-3898-x
4. Bae J, Theologis AA, Strom R, et al. Comparative analysis of 3 surgical strategies for adult spinal deformity with mild to moderate sagittal imbalance. J Neurosurg Spine. 2018;28(1):40-49. doi:10.3171/2017.5.SPINE161370
5. Drazin D, Shirzadi A, Rosner J, et al. Complications and outcomes after spinal deformity surgery in the elderly: review of the existing literature and future directions. Neurosurg Focus. 2011;31(4):E3. doi:10.3171/2011.7.FOCUS11145
6. Beschloss A, Dicindio C, Lombardi J, et al. Marked Increase in Spinal Deformity Surgery Throughout the United States. Spine (Phila Pa 1976). 2021;46(20):1402-1408. doi:10.1097/BRS.0 000000000004041
7. Charosky S, Guigui P, Blamoutier A, Roussouly P, Chopin D. Complications and risk factors of primary adult scoliosis surgery: a multicenter study of 306 patients. Spine (Phila Pa 1976). 2012;37(8): 693-700. doi:10.1097/BRS.0b013e31822ff5c1
8. Ham DW, Kim HJ, Choi JH, Park J, Lee J, Yeom JS. Validity of the global alignment proportion (GAP) score in predicting mechanical complications after adult spinal deformity surgery in elderly patients. Eur Spine J. 2021;30(5):1190-1198. doi:10.1007/s0 0586-021-06734-2
9. Kim HJ, Bridwell KH, Lenke LG, et al. 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):E576-80. doi:10.1097/B RS.0000000000000246
10. 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): 2179-2184.
11. 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. Spine Deform. 2013;1(4):299-305.
12. Yagi M, Rahm M, Gaines R, et al. Characterization and surgical outcomes of proximal junctional failure in surgically treated patients with adult spinal deformity. Spine (Phila Pa 1976). 2014; 39(10):E607-E614.
13. Kim HJ, Bridwell KH, Lenke LG, et al. Proximal junctional kyphosis results in inferior SRS pain subscores in adult deformity patients. Spine (Phila Pa 1976). 2013;38(11):896-901.
14. Hostin RA, Yeramaneni S, Gum JL, Smith JS. Clinical and Economic Impact of Proximal Junctional Kyphosis on Pediatric and Adult Spinal Deformity Patients. Int J Spine Surg. 2023;17(S2): S9-S17. doi:10.14444/8518
15. McCarthy IM, Hostin RA, O’Brien MF, et al. Analysis of the direct cost of surgery for four diagnostic categories of adult spinal deformity. The Spine Journal. 2013;13(12):1843-1848.
16. Fakhre E, Kelly MJ, Mo FF. Proximal junctional kyphosis. Semin Spine Surg. 2022;34(1):100926. doi:https://doi.org/10.1016/j.semss.2022.100926
17. Lee J, Park YS. Proximal Junctional Kyphosis: Diagnosis, Pathogenesis, and Treatment. Asian Spine J. 2016;10(3):593-600. doi:10.4184/asj.201 6.10.3.593
18. Shen T, Shahzad H, Sierra F, et al. Osteoporosis Treatment and Outcomes in Patients Undergoing Adult Spinal Deformity Surgery. World Neurosurg. 2024;190:e1018-e1024. doi:10.1016/j. wneu.2024.08.053
19. Yao YC, Elysee J, Lafage R, et al. Preoperative Hounsfield Units at the Planned Upper Instrumented Vertebrae May Predict Proximal Junctional Kyphosis in Adult Spinal Deformity. Spine (Phila Pa 1976). 2021;46(3):E174-E180. doi:10.1097/BRS.0000000000003798
20. Yagi M, Ohne H, Konomi T, et al. Teriparatide improves volumetric bone mineral density and fine bone structure in the UIV+1 vertebra, and reduces bone failure type PJK after surgery for adult spinal deformity. Osteoporos Int. 2016;27(12):3495-3502. doi:10.1007/s00198-016-3676-6
21. Puvanesarajah V, Shen FH, Cancienne JM, et al. Risk factors for revision surgery following primary adult spinal deformity surgery in patients 65 years and older. Journal of Neurosurgery: Spine SPI. 2016;25(4):486-493. doi:10.3171/2016.2.SPIN E151345
22. Varshneya K, Jokhai RT, Fatemi P, et al. Predictors of 2-year reoperation in Medicare patients undergoing primary thoracolumbar deformity surgery. J Neurosurg Spine. Published online July 2020:1-5. doi:10.3171/2020.5.SPINE191425
23. Noh SH, Ha Y, Obeid I, et al. Modified global alignment and proportion scoring with body mass index and bone mineral density (GAPB) for improving predictions of mechanical complications after adult spinal deformity surgery. Spine J. 2020; 20(5):776-784. doi:10.1016/j.spinee.2019.11.006
24. Mohanty S, Sardar ZM, Hassan FM, Lombardi JM, Lehman RA, Lenke LG. Impact of Teriparatide on Complications and Patient-Reported Outcomes of Patients Undergoing Long Spinal Fusion According to Bone Density. J Bone Joint Surg Am. 2024;106(3):206-217. doi:10.2106/JBJS.23.00272
25. Amin RM, Raad M, Jain A, et al. Risk factors for nonroutine discharge in adult spinal deformity surgery. The Spine Journal. 2019;19(2):357-363.
26. Zhang D, Gao X, Ding W, Cui H. Predictors and correlative factors for low back pain after long fusion arthrodesis in patients with adult scoliosis. Adv Ther. 2021;38(7):3803-3815.
27. Passias PG, Bortz CA, Lafage V, et al. Durability of satisfactory functional outcomes following surgical adult spinal deformity correction: a 3-year survivorship analysis. Operative Neurosurgery. 2020;18(2):118-125.
28. Varshneya K, Bhattacharjya A, Jokhai RT, et al. The impact of osteoporosis on adult deformity surgery outcomes in Medicare patients. European Spine Journal. 2022;31(1):88-94. doi:10.1007/s00 586-021-06985-z
29. Wright NC, Looker AC, Saag KG, et al. The recent prevalence of osteoporosis and low bone mass in the United States based on bone mineral density at the femoral neck or lumbar spine. J Bone Miner Res. 2014;29(11):2520-2526. doi:10.1002/jb mr.2269
30. Kuprys TK, Steinmetz LM, Fischer CR, et al. Preoperative Assessment of Bone Quality in Spine Deformity Surgery: Correlation With Clinical Practice and Published Recommendations. Spine (Phila Pa 1976). 2019;44(12):E735-E741. doi:10.1097/BRS.0 000000000002956
31. Dipaola CP, Bible JE, Biswas D, Dipaola M, Grauer JN, Rechtine GR. Survey of spine surgeons on attitudes regarding osteoporosis and osteomalacia screening and treatment for fractures, fusion surgery, and pseudoarthrosis. Spine J. 2009;9(7):537-544. doi:10.1016/j.spinee.2009.02.005
32. Gupta A, Upadhyaya S, Patel A, et al. DEXA sensitivity analysis in patients with adult spinal deformity. Spine J. 2020;20(2):174-180. doi:10.10 16/j.spinee.2019.08.011
33. Arora A, Cummins DD, Wague A, et al. Preoperative medical assessment for adult spinal deformity surgery: a state-of-the-art review. Spine Deform. 2023;11(4):773-785. doi:10.1007/s43390-023-00654-5
34. Li QD, Yang JS, He BR. Risk factors for proximal junctional kyphosis after posterior long-segment internal fixation for chronic symptomatic osteoporotic thoracolumbar fractures with kyphosis. BMC Surg. 2022;22(1):189.
35. Hyun SJ, Kim YJ, Rhim SC. Patients with proximal junctional kyphosis after stopping at thoracolumbar junction have lower muscularity, fatty degeneration at the thoracolumbar area. Spine J. 2016;16(9):1095-1101.
36. Hills JM, Weisenthal BM, Wanner JP. A patient-specific approach to alignment and proximal junctional kyphosis risk assessment in adult spinal deformity surgery: development and validation of a predictive tool. Clin Spine Surg. 2022;35(6):256-263.
37. Wang H, Ding W, Ma L, Zhang L, Yang D. Prevention of proximal junctional kyphosis: are polyaxial pedicle screws superior to monoaxial pedicle screws at the upper instrumented vertebrae? World Neurosurg. 2017;101:405-415.
38. Wang Q, Wang C, Zhang X. Correlation of vertebral trabecular attenuation in Hounsfield units and the upper instrumented vertebra with proximal junctional failure after surgical treatment of degenerative lumbar disease. J Neurosurg Spine. 2021;34(3):456-463.
39. Yagi M, Fujita N, Tsuji O. Low bone-mineral density is a significant risk for proximal junctional failure after surgical correction of adult spinal deformity: a propensity score-matched analysis. Spine (Phila Pa 1976). 2018;43(7):485-491.
40. Yuan L, Zeng Y, Chen Z, Li W, Zhang X, Mai S. Degenerative lumbar scoliosis patients with proximal junctional kyphosis have lower muscularity, fatty degeneration at the lumbar area. Eur Spine J. 2021;30(5):1133-1143.
41. Chen JW, McCandless MG, Bhandarkar AR, et al. The association between bone mineral density and proximal junctional kyphosis in adult spinal deformity: a systematic review and meta-analysis. J Neurosurg Spine. 2023;39(1):82-91. doi:https://doi.org/10.3171/2023.2.SPINE221101
42. Kim JS, Phan K, Cheung ZB. Surgical, radiographic, and patient-related risk factors for proximal junctional kyphosis: a meta-analysis. Global Spine J. 2019;9(1):32-40.
43. Park SJ, Lee CS, Park JS, Jeon CY, Ma CH, Shin TS. Risk factors for radiographic progression of proximal junctional fracture in patients undergoing surgical treatment for adult spinal deformity. J Neurosurg Spine. 2023;39(6):765-773. doi:https://doi.org/10.3171/2023.7.SPINE23103
44. 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):279-286. doi:10.1227/NEU.0000000000001240
45. Halvorson TL, Kelley LA, Thomas KA, et al. Effects of Bone Mineral Density on Pedicle Screw Fixation. Spine (Phila Pa 1976). 1994;19(21):2415-2420. doi:10.1097/00007632-199411000-00008
46. Shea TM, Laun J, Gonzalez-Blohm SA, et al. Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: current status. Biomed Res Int. 2014;2014:748393. doi:10.1155/2014/748393
47. Gupta A, Cha T, Schwab J, et al. Osteoporosis increases the likelihood of revision surgery following a long spinal fusion for adult spinal deformity. Spine J. 2021;21(1):134-140. doi:10.1016/j.spinee.2020.08.002
48. Eastell R, Mitlak BH, Wang Y, Hu M, Fitzpatrick LA, Black DM. Bone turnover markers to explain changes in lumbar spine BMD with abaloparatide and teriparatide: results from ACTIVE. Osteoporos Int. 2019;30(3):667-673. doi:10.1007/s 00198-018-04819-1
49. Sahbani K, Cardozo CP, Bauman WA, Tawfeek HA. Abaloparatide exhibits greater osteoanabolic response and higher cAMP stimulation and β-arrestin recruitment than teriparatide. Physiol Rep. 2019;7(19):e14225. doi:10.14814/phy2.14225
50. Ohtori S, Inoue G, Orita S, et al. Teriparatide accelerates lumbar posterolateral fusion in women with postmenopausal osteoporosis: prospective study. Spine (Phila Pa 1976). 2012;37(23):E1464-8. doi:10.1097/BRS.0b013e31826ca2a8