Selective thoracolumbar fusion in adult spinal deformity double curves with circumferential minimally invasive surgery: 2-year minimum follow-up

Presented at the 2023 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Neel Anand Department of Orthopedics, Cedars-Sinai Spine Center, Los Angeles, California;

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Jerry Robinson Department of Orthopedics, University of Pittsburgh Medical Center, Harrisburg, Pennsylvania;

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Andrew Chung Department of Orthopedics, Banner Health, Phoenix, Arizona;

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David Gendelberg Department of Orthopedics, University of California, San Francisco Orthopedics Trauma Institute, San Francisco, California;

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José H. Jiménez-Almonte Department of Orthopedics, Central Florida Bone & Joint Institute, Orange City, Florida; and

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Sheila Kahwaty Department of Orthopedics, Cedars-Sinai Spine Center, Los Angeles, California;

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Babak Khandehroo Department of Orthopedics, Cedars-Sinai Spine Center, Los Angeles, California;

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Corey Walker Department of Neurosurgery, Cedars-Sinai Spine Center, Los Angeles, California

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OBJECTIVE

Selection of the upper instrumented vertebra (UIV) level for adult spinal deformity (ASD) remains controversial. Although selective fusion attempts have been described for fractional curves or adolescent curves, no authors have described selective thoracolumbar fusion performance for ASD with double curves. This study evaluated the clinical impact of selective fusion constructs within the lower thoracic and/or lumbar spine on ASD with double curves.

METHODS

A retrospective review was performed on an ASD (Cobb angle > 20°, sagittal vertical axis [SVA] > 50 mm, and pelvic incidence minus lumbar lordosis mismatch [PI-LL] > 10°) database consisting of 438 patients who underwent correction with circumferential minimally invasive surgery (CMIS) between 2007 and 2020. The inclusion criteria were ASD double curves (lumbar Cobb angle > 35° and thoracic Cobb angle > 30°), 4 or more levels fused, and minimum 2-year follow-up. Analyses were performed on spinopelvic data and clinical outcome scores. Complications were recorded, specifically the need for revision surgery and hardware-related complications.

RESULTS

Twenty-one ASD double curve patients underwent selective correction with a mean ± SD (range) follow-up of 91 ± 43 (24–174) months. A total of 141 levels were fused with a mean of 6.7 ± 1.3 (4–8) levels. T10 was the most proximal and most common UIV (10/21 [48%]). Pelvic fixation was performed in 12 patients (57%). Significant improvements in lumbar Cobb angle, thoracic Cobb angle, coronal balance, lumbar lordosis, thoracic kyphosis, SVA, and PI-LL were achieved. The uninstrumented thoracic spine demonstrated 14.5° of mean coronal correction and a mean increase of 9.4° in kyphosis. Significant improvements in visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were observed. Four patients required revision for the following reasons: 1) superficial wound infection requiring irrigation and debridement; 2) bilateral L5 pars fractures requiring L5–S1 anterior lumbar interbody fusion and pelvic fixation; 3) adjacent-segment degeneration at L5–S1 requiring anterior lumbar interbody fusion and pelvic fixation; and 4) proximal junctional kyphosis requiring revision fusion to include the entire thoracic curve. There were no instances of hardware failure such as rod breakage or screw loosening.

CONCLUSIONS

Selective thoracolumbar fusion with CMIS for ASD double curves can provide significant clinical improvements. Despite limiting fusion constructs to within the lower thoracic and/or lumbar spine, significant correction can be observed in the uninstrumented thoracic curve. The rate of mechanical complications was low, and the 2-year follow-up results suggested that limited fusion constructs are viable options for ASD double curve patients.

ABBREVIATIONS

ALIF = anterior lumbar interbody fusion; ASD = adult spinal deformity; CMIS = circumferential minimally invasive surgery; LIV = lower instrumented vertebra; LL = lumbar lordosis; ODI = Oswestry Disability Index; PI = pelvic incidence; PI-LL = PI minus LL mismatch; PJK = proximal junctional kyphosis; PT = pelvic tilt; SRS-22 = Scoliosis Research Society-22 questionnaire; SS = sacral slope; SVA = sagittal vertical axis; TK = thoracic kyphosis; UIV = upper instrumented vertebra; VAS = visual analog scale.

OBJECTIVE

Selection of the upper instrumented vertebra (UIV) level for adult spinal deformity (ASD) remains controversial. Although selective fusion attempts have been described for fractional curves or adolescent curves, no authors have described selective thoracolumbar fusion performance for ASD with double curves. This study evaluated the clinical impact of selective fusion constructs within the lower thoracic and/or lumbar spine on ASD with double curves.

METHODS

A retrospective review was performed on an ASD (Cobb angle > 20°, sagittal vertical axis [SVA] > 50 mm, and pelvic incidence minus lumbar lordosis mismatch [PI-LL] > 10°) database consisting of 438 patients who underwent correction with circumferential minimally invasive surgery (CMIS) between 2007 and 2020. The inclusion criteria were ASD double curves (lumbar Cobb angle > 35° and thoracic Cobb angle > 30°), 4 or more levels fused, and minimum 2-year follow-up. Analyses were performed on spinopelvic data and clinical outcome scores. Complications were recorded, specifically the need for revision surgery and hardware-related complications.

RESULTS

Twenty-one ASD double curve patients underwent selective correction with a mean ± SD (range) follow-up of 91 ± 43 (24–174) months. A total of 141 levels were fused with a mean of 6.7 ± 1.3 (4–8) levels. T10 was the most proximal and most common UIV (10/21 [48%]). Pelvic fixation was performed in 12 patients (57%). Significant improvements in lumbar Cobb angle, thoracic Cobb angle, coronal balance, lumbar lordosis, thoracic kyphosis, SVA, and PI-LL were achieved. The uninstrumented thoracic spine demonstrated 14.5° of mean coronal correction and a mean increase of 9.4° in kyphosis. Significant improvements in visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were observed. Four patients required revision for the following reasons: 1) superficial wound infection requiring irrigation and debridement; 2) bilateral L5 pars fractures requiring L5–S1 anterior lumbar interbody fusion and pelvic fixation; 3) adjacent-segment degeneration at L5–S1 requiring anterior lumbar interbody fusion and pelvic fixation; and 4) proximal junctional kyphosis requiring revision fusion to include the entire thoracic curve. There were no instances of hardware failure such as rod breakage or screw loosening.

CONCLUSIONS

Selective thoracolumbar fusion with CMIS for ASD double curves can provide significant clinical improvements. Despite limiting fusion constructs to within the lower thoracic and/or lumbar spine, significant correction can be observed in the uninstrumented thoracic curve. The rate of mechanical complications was low, and the 2-year follow-up results suggested that limited fusion constructs are viable options for ASD double curve patients.

In Brief

The authors detail their experience performing selective minimally invasive thoracolumbar fusion constructs on adult spinal deformity patients with double curves (presence of both a lumbar and thoracic curve). Limited constructs involving only the lumbar and/or lower thoracic spine performed well at minimum 2-year follow-up with low complication rates. This technique is a departure from the traditional viewpoint that both curves need to be included to avoid complications.

Clinical disability associated with adult spinal deformity (ASD) has been well documented.1,2 While trends in surgical treatment have changed throughout the decades,3 no clear consensus has emerged regarding the optimal treatment strategy for this patient population.4 This is partly attributable to the diverse nature of ASD, encompassing a wide variety of curve magnitudes, locations, and shapes.58

The morbidity associated with traditional deformity correction9 has led to the development of intraoperative techniques aimed at complication avoidance, specifically the prevention of proximal junctional kyphosis (PJK)/proximal junctional failure.1013 Although these techniques have been widely advocated, their adoption seems to have had limited efficacy.14 This has led other authors to advocate for circumferential minimally invasive surgery (CMIS) as an alternative to open surgery for the correction of ASD.1518 CMIS correction for ASD has been associated with reduction in complications19 but has been traditionally limited in its ability to handle more complex deformity.1921

Another debated treatment decision involves the selection of the upper instrumented vertebra (UIV) for ASD correction.2224 Many factors contribute to UIV selection. Factors such as magnitude of sagittal deformity, magnitude of coronal deformity, number of curves, curve flexibility, and bone quality are cited as important factors in the treatment algorithms of many surgeons.2527 Selective fusion attempts to fractional curves28 or adolescent idiopathic scoliosis have been performed,29 but no publications describe the clinical outcomes of CMIS selective fusion for ASD patients with double curves (both thoracic and lumbar coronal deformities).

We hypothesized that limiting fusion to the lower thoracic and/or lumbar curves would provide significant clinical benefit without an increase in mechanical complications. We report 2-year clinical outcome data regarding ASD double curves treated with the UIV remaining in the lower thoracic and/or lumbar spine. Additionally, reciprocal changes30 in the uninstrumented thoracic deformity are detailed.

Methods

We conducted a retrospective review of an ASD (coronal Cobb angle > 20°, sagittal vertical axis [SVA] > 50 mm, and pelvic incidence [PI] minus lumbar lordosis [LL] mismatch [PI-LL] > 10°) database. The database consisted of 438 patients who had undergone deformity correction with CMIS during the years 2007 to 2020. Inclusion criteria were adults > 18 years of age, deformities with double curves (lumbar coronal Cobb angle > 35° and thoracic coronal Cobb angle > 30°), 4 or more levels fused, and at least 2 years of follow-up. Exclusion criteria were deformity due to acute trauma, infection, or tumor and patients with diffusely ankylosed or fused spines. The patients included for analysis were nonconsecutive operative patients.

Statistical analysis was performed on preoperative, 3-month postoperative, and last known follow-up data beyond 2 years for the following clinical outcome scores: visual analog scale (VAS), Oswestry Disability Index (ODI), Scoliosis Research Society-22 questionnaire (SRS-22), and SF-36. Radiographic parameters evaluated preoperatively and at last known follow-up beyond 2 years included the lumbar Cobb angle, thoracic Cobb angle, coronal balance, LL, thoracic kyphosis (TK), SVA, PI-LL, PI, pelvic tilt (PT), and sacral slope (SS). Complications were recorded, specifically the need for revision surgery and hardware-related complications.

Statistical Analysis

The Student t-test was performed, with p < 0.05 indicating significance for the analysis of preoperative and postoperative spinopelvic parameters. This was also used for evaluation of preoperative and final follow-up clinical outcome scores.

Surgical Technique and Patient Selection

The surgical CMIS technique of the senior author (N.A.) has been described in previous publications.15,31,32 In brief, it consists of first-stage anterior and/or lateral interbody fusions, followed by delayed second-stage percutaneous or muscle-sparing pedicle screw instrumented fusion with aggressive rod contouring, derotation, and translation reduction of the deformity. No osteotomies are performed during the posterior approach; however, stage 2 of the protocol includes minimally invasive posterolateral fusion at the spinal levels that do not include interbody fusion cages. For example, in a CMIS construct for ASD planned from T10 to L5, the levels from L1 to L5 would receive anterior and/or lateral interbody fusion cages during stage 1. Stage 2 would consist of posterior instrumentation from T10 to L5. Because L1–5 has interbody cages as the primary means for achieving fusion, fusion still needs to take place from T10 to L1, and this is achieved through minimally invasive posterolateral fusion. This ensures that all levels included in the construct achieve fusion.

It should be noted that the senior author always obtains MR images of the lumbar spine, CT scans of the thoracolumbopelvic spine, and upright full-length scoliosis radiographs, as well as performs a bone density evaluation (dual-energy x-ray absorptiometry) prior to any deformity operation. This allows for full analysis of the spine prior to the planned deformity correction. Patient selection is paramount, and previously described criteria for successful indirect decompression are utilized.33,34 Spinal bending radiographs are not routinely obtained to evaluate spinal flexibility. Instead, the senior author prefers CT scan evaluation for spinal ankylosis. Absence of ankylosis is the preferred method for evaluating spinal deformity rigidity. As previously mentioned, osteotomies are not performed during the posterior stage of the deformity correction; therefore, a nonankylosed spine is a prerequisite for posterior non–osteotomy-based deformity correction.

It should be noted that staging is necessary to evaluate the degree of residual imbalance after first-stage anterior and/or lateral interbody placement.35 If a patient has severe residual TK (> 60°) or severe residual coronal imbalance (> 3 cm from the central sacral vertical line), posterior fusion would be extended into the upper thoracic spine. Although previous authors have stated that minimally invasive surgical techniques do not adequately address severe malalignment,36 the senior author has demonstrated that even severe deformity can be addressed with CMIS techniques.37

Instrumentation Level Selection

The senior author’s philosophy on level selection focuses on treating the symptomatic lumbar curve and allowing for reciprocal thoracic deformity correction. The entire lumbar coronal Cobb angle must be instrumented and fused. The senior author does not stop instrumentation at the curve apex of any coronal deformity. Standard indications for pelvic instrumentation are followed;38 however, if the patient has a healthy, nondegenerated L5–S1 disc without disc space obliquity, the senior author may decide to end fixation at L5 and not extend the long fusion to the sacrum or pelvis.39 The UIV is selected to include 1) the entire lumbar coronal Cobb angle; 2) the caudal-most neutral vertebral body (i.e., the nonrotated vertebra); and 3) the nondegenerated disc space above the anticipated UIV.

In Fig. 1, the patient has ASD with a double curve and previous L4–5 instrumented fusion. The patient presented with severe low-back pain and mild L5 radiculopathy. First, to decide if the patient is a CMIS candidate, a full deformity workup must be obtained (as described above). The patient’s previous L4–5 fusion was solidly fused, and the remainder of the spine was nonankylosed. The patient was deemed an appropriate candidate for non–osteotomy-based deformity correction with CMIS. For level selection, the entire lumbar coronal Cobb angle is to be included (L1–5). The patient had mild L5 radiculopathy and L5–S1 disc space collapse, so L5–S1 was to be included in the construct. Because our fusion construct included L5–S1 and must span to at least L1 (i.e., the entire lumbar coronal Cobb angle), pelvic instrumentation is to be utilized. Next, we must span to the caudal-most neutral vertebral body (in this case, T10). Lastly, we evaluate the disc space immediately above our intended UIV (T9–10 disc space). It was without degeneration and was deemed an appropriate stopping point for this deformity. Therefore, our fusion construct was T10–pelvis.

FIG. 1.
FIG. 1.

Selection of instrumentation levels. This is a 79-year-old female with an ASD double curve. The patient presented with refractory low-back pain and mild L5 radiculopathy. She had a previous L4–5 transforaminal interbody fusion that fused solidly. Spinopelvic parameters were as follows: PI 60°, LL 20°, PI-LL 40°, PT 48°, C7–SVA +4 cm, TK 10°, T2–L1 coronal Cobb angle 35°, and L1–5 coronal Cobb angle 45°. The central sacral vertical line was balanced. The patient had an obliquely collapsed L5–S1 disc and mild radiculopathy, so the decision was made to include L5–S1 in our deformity correction/instrumentation. We included the entire lumbar Cobb angle (L1–5), and because this was a long fusion construct including L5–S1, we performed pelvic instrumentation. For UIV selection, we go to at least L1 (to include the entire lumbar coronal Cobb angle), but we must reach the caudal-most neutral vertebral body (in this case, T10). Lastly, we checked on CT and MRI to evaluate the disc at T9–10. This disc was healthy, without degeneration or herniation/stenosis. Therefore, our construct was placed from T10 to the pelvis via the senior author’s described CMIS protocol.15

Figure 2 demonstrates the surgical correction of Fig. 1 with reciprocal changes of the uninstrumented thoracic spine. Notice that the patient’s preoperative hypokyphosis has improved to balanced TK that is appropriate for her deformity correction.

FIG. 2.
FIG. 2.

Selective CMIS fusion of an ASD double curve. This is the patient from Fig. 1 who underwent CMIS selective fusion from T10 to the pelvis with excellent reciprocal change in the uninstrumented thoracic spine. The patient’s thoracic coronal Cobb angle was reduced to 10°, with TK of 35°. This was performed without the use of osteotomies through an entirely minimally invasive surgical approach.

Results

Twenty-one ASD double curve patients underwent selective deformity correction with a mean ± SD (range) follow-up of 91 ± 43 (24–174) months. A total of 141 levels were fused with a mean of 6.7 ± 1.3 (4–8) fusion levels per patient.

Table 1 demonstrates the distributions of UIV and lower instrumented vertebra (LIV). T10 was the most proximal and most common UIV (10/21 [48%]). Pelvic fixation was the most common LIV and was performed in 12/21 patients (57%).

TABLE 1.

UIV/LIV distribution in patients with ASD double curve

Instrumented VertebraNo. of Patients
UIV
 T1010
 T114
 T126
 L21
LIV
 Pelvis12
 S14
 L53
 L41
 L31

Table 2 summarizes the preoperative and postoperative radiographic parameters and their statistical significance. Compared to preoperatively, statistically significant improvements in the lumbar Cobb angle (51.5° vs 19.2°, p < 0.05), thoracic Cobb angle (42.7° vs 28.2°, p < 0.05), coronal balance (29.3 mm vs 12.5 mm, p < 0.05), LL (36.5° vs 46.6°, p < 0.05), TK (33.7° vs 43.1°, p < 0.05), SVA (49.3 mm vs 18.9 mm, p < 0.05), and PI-LL (19.9° vs 10.8°, p < 0.05) were achieved. There were no statistically significant changes in PI, PT, or SS (p > 0.05). The uninstrumented thoracic deformity underwent an average coronal correction of 14.5°, with an increase in kyphosis of 9.4°.

TABLE 2.

Preoperative and postoperative ASD radiographic parameters

ParameterPreopPostopp Value*
Cobb angle
 Lumbar51.5 ± 11.4 (35–74.7)19.2 ± 12.7 (1.3–48.2)<0.05
 Thoracic42.7 ± 10.1 (30–57)28.2 ± 11.8 (4–42)<0.05
Coronal balance29.3 ± 16.4 (12–69.8)12.5 ± 7.7 (0–22)<0.05
LL36.5 ± 15.9 (9.1–64)46.6 ± 8.8 (24–59.1)<0.05
TK33.7 ± 12.9 (9–59)43.1 ± 8.2 (29.7–61)<0.05
SVA49.3 ± 39.2 (27.6–114.7)18.9 ± 17 (5–69.2)<0.05
PI-LL19.9 ± 13.1 (4.3–49.5)10.8 ± 11.5 (0.1–47.3)<0.05
PI53.8 ± 8.9 (39.3–74.1)52.6 ± 8.7 (40.1–71.3)>0.05
PT26.6 ± 8.5 (13.3–38)23.8 ± 9.7 (3.1–39.1)>0.05
SS26.8 ± 11 (12–48.6)29.9 ± 6.6 (16.4–42.7)>0.05

Values are shown as mean ± SD (range).

Notice that significant improvements in the spinopelvic parameters were achieved through the CMIS ASD correction protocol.

Reciprocal changes within the uninstrumented thoracic deformity were also observed, with an average improvement of 14.5° in coronal Cobb angle correction and an average increase of 9.4° in kyphosis.

Table 3 summarizes the clinical outcome scores evaluated during the study period. By final follow-up, statistically significant improvements in ODI (44.2 vs 21.3, p < 0.05) and VAS (5.4 vs 2.0, p < 0.05) outcome scores were present. There were no statistically significant differences in SRS-22 or SF-36 scores (p > 0.05).

TABLE 3.

Clinical outcome scores of patients with ASD double curve

Patient-Reported Outcome MeasurePreop3 mos PostopLast Follow-Upp Value*
VAS5.4 ± 2.5 (2–10)2.4 ± 2.9 (0–8)2 ± 2.7 (0–7)<0.05
ODI44.2 ± 19.4 (13.3–80)27 ± 22.7 (0–72)21.3 ± 20.2 (0–60)<0.05
SRS-223 ± 0.5 (2.1–3.7)3.5 ± 0.9 (2.2–4.5)3.9 ± 0.8 (2.4–4.8)>0.05
SF-3642.1 ± 21.5 (16–98)48.5 ± 23.4 (10–96)49.9 ± 17 (20–70)>0.05

Values are shown as mean ± SD (range).

Statistically significant improvements were observed at final follow-up in VAS and ODI, but not SRS-22 and SF-36.

Four patients required revision surgery for the following reasons: 1) superficial wound infection requiring irrigation and debridement; 2) bilateral L5 pars fractures requiring L5–S1 anterior lumbar interbody fusion (ALIF) and pelvic fixation; 3) adjacent-segment degeneration at L5–S1 requiring ALIF and pelvic fixation; and 4) PJK requiring revision fusion to include the entire thoracic curve. There were no instances of hardware failure such as rod breakage or screw loosening.

Discussion

This study contributes to the growing body of literature, demonstrating postoperative reciprocal changes within the uninstrumented spine. Our study is unique in that coronal and sagittal profile reciprocal changes were demonstrated within true thoracic deformities. Other authors have investigated the impact of thoracic compensation after lumbar spine surgery,25,40 with some recommending extension of fusion to the upper thoracic spine to eliminate undesirable reciprocal changes and protect against PJK.40 Protopsaltis et al. found that the presence of preoperative thoracic hypokyphosis (a compensatory mechanism of ASD) was a predictor of increased reciprocal postoperative TK and correlated this with an increased rate of PJK.41 Our review identified only one instance of PJK, and we were therefore unable to correlate this with preoperative hypokyphosis. Despite this, we favor an alternative perspective, as we favorably view preoperative compensatory alignment as a sign of deformity flexibility.40

The abovementioned observations have led to attempts to predict postoperative reciprocal changes within the uninstrumented spine. Ishikawa et al. reported on a novel technique to predict expected thoracic compensation after lumbar spine surgery.30 By measuring the T1-UIV sagittal Cobb angle on preoperative full-length spine flexion radiography, they were able to demonstrate a correlation with postoperative thoracic alignment.30 We do not routinely obtain full-length bending radiographs, so we are unable to validate this technique.

In addition to the sagittal alignment of the thoracic spine, others have cited coronal deformity as a determinant for upper thoracic UIV selection.22,27 Virk et al. proposed an algorithm for UIV selection with upper thoracic criteria, including TK > 55° or coronal Cobb angle > 20°.27 If this treatment algorithm would have been utilized, every patient within this publication would have received a UIV in the upper thoracic spine. Alternatively, our entire cohort received a UIV at or below T10, with only 1 patient with PJK requiring upper thoracic instrumentation. Because our protocol assesses the degree of residual malalignment after stage 1, the spine can undergo reciprocal changes and correct itself. We believe this staging allows a more limited fusion construct to be achieved.

Additionally, because our protocol is staged, this may allow reciprocal changes to occur within the pelvis, specifically improvements in PT. When staging does not occur, posterior instrumentation effectively locks the pelvis in a fixed relation to the now corrected lumbar spine. Passias et al. demonstrated a nearly 25% pelvic nonresponse rate after ASD correction and correlated it to undercorrection of the deformity.42 These patients additionally had less improvement in pain postoperatively. This study was unable to evaluate the pelvic nonresponse rate and its influence on clinical outcomes due to the small sample size and lack of statistical significance in pre- and postoperative PT measurements. Despite this, we still believe that staging represents a significant factor in allowing spinal reciprocal changes.

Lastly, our patient cohort contained 2 patients with distal junctional failure requiring revision surgery. Meta-analyses have demonstrated distinct differences between long fusion constructs to the sacrum/pelvis versus those to L5.39 Jia et al. noted that fusion to L5 was advantageous in terms of preventing pseudarthrosis and PJK, whereas fusion to the sacrum/pelvis resulted in superior alignment restoration/maintenance with the absence of distal junctional breakdown.39 Although we cannot draw definitive conclusions, our study potentially echoes these findings. We recognize that there are many factors involved with the decision to include the lumbosacral junction.

Our study possesses several limitations, most importantly in that these patients were treated with CMIS techniques. Application of selective fusion in ASD double curve patients may have different outcomes and complication profiles if performed with open techniques. Furthermore, this was a single-surgeon series of limited sample size, without a comparison cohort. It should also be noted that there was a wide range in follow-up in this cohort (24–174 months). Patient-reported outcomes have been documented to continue to improve at 5 years or more.43 Studies with a longer minimum follow-up are needed to evaluate the longevity of limited fusion constructs. Conclusions cannot be drawn about selective fusion performance versus upper thoracic UIV selection for double curves, as there was no comparative cohort within this study. Further studies with larger sample size and external validation are necessary.

Conclusions

Selective thoracolumbar fusion with CMIS for ASD double curves can provide significant clinical and radiographic improvements. Despite limiting fusion constructs to the lower thoracic and/or lumbar spine, we observed significant reciprocal correction in the uninstrumented thoracic deformity. The rate of mechanical complications was low, and the minimum 2-year follow-up results suggest that limited fusion constructs are viable options for ASD double curve patients.

Disclosures

Dr. Anand reported personal fees and grants from Medtronic; stock options from Spinal Balance, On-Point Surgical, and Spinal Simplicity; and personal fees from Viseon and ISTO Surgical during the conduct of the study; in addition, Dr. Anand had a patent for Medtronic issued, as well as patents with royalties paid for Globus Medical, Elsevier, and Medtronic.

Author Contributions

Conception and design: all authors. Acquisition of data: Anand, Jiménez-Almonte, Khandehroo. Analysis and interpretation of data: Robinson, Anand, Chung, Gendelberg, Jiménez-Almonte, Khandehroo, Walker. Drafting the article: Robinson, Anand, Gendelberg, Jiménez-Almonte. Critically revising the article: Robinson, Anand, Chung, Gendelberg, Jiménez-Almonte, Walker. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Robinson. Statistical analysis: Jiménez-Almonte. Administrative/technical/material support: Anand, Jiménez-Almonte, Kahwaty, Khandehroo. Study supervision: Anand, Jiménez-Almonte, Khandehroo.

Supplemental Information

Previous Presentations

Robinson J. Selective thoracolumbar fusion in adult spinal deformity (ASD) double curves with circumferential minimally invasive surgery (CMIS): 2-year minimum follow up [conference abstract presentation], AANS Spine Summit 2023, Miami, FL, March 16–19, 2023.

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    • Export Citation
  • 16

    Uribe JS, Beckman J, Mummaneni PV, et al. Does MIS surgery allow for shorter constructs in the surgical treatment of adult spinal deformity? Neurosurgery. 2017;80(3):489497.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Mummaneni PV, Park P, Fu KM, et al. Does minimally invasive percutaneous posterior instrumentation reduce risk of proximal junctional kyphosis in adult spinal deformity surgery? A propensity-matched cohort analysis. Neurosurgery. 2016;78(1):101108.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Park P, Wang MY, Lafage V, et al. Comparison of two minimally invasive surgery strategies to treat adult spinal deformity. J Neurosurg Spine. 2015;22(4):374380.

  • 19

    Lak AM, Lamba N, Pompilus F, et al. Minimally invasive versus open surgery for the correction of adult degenerative scoliosis: a systematic review. Neurosurg Rev. 2021;44(2):659668.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Chou D, Mundis G, Wang M, et al. Minimally invasive surgery for mild-to-moderate adult spinal deformities: impact on intensive care unit and hospital stay. World Neurosurg. 2019;127:e649e655.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Mummaneni PV, Park P, Shaffrey CI, et al. The MISDEF2 algorithm: an updated algorithm for patient selection in minimally invasive deformity surgery. J Neurosurg Spine. 2019;32(2):221228.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Daniels AH, Reid DBC, Durand WM, et al. Upper-thoracic versus lower-thoracic upper instrumented vertebra in adult spinal deformity patients undergoing fusion to the pelvis: surgical decision-making and patient outcomes. J Neurosurg Spine. 2020;32(4):600606.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Luo M, Wang P, Wang W, Shen M, Xu G, Xia L. Upper thoracic versus lower thoracic as site of upper instrumented vertebrae for long fusion surgery in adult spinal deformity: a meta-analysis of proximal junctional kyphosis. World Neurosurg. 2017;102:200208.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Fu X, Sun XL, Harris JA, et al. Long fusion correction of degenerative adult spinal deformity and the selection of the upper or lower thoracic region as the site of proximal instrumentation: a systematic review and meta-analysis. BMJ Open. 2016;6(11):e012103.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Ohba T, Koji F, Koyama K, et al. Preoperative radiographic evaluation of thoracic flexibility and compensation for adult spinal deformity surgery. how to select optimal upper instrumented vertebra to prevent proximal junctional kyphosis. Spine (Phila Pa 1976). 2022;47(2):144152.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Kim HJ, Boachie-Adjei O, Shaffrey CI, et al. Upper thoracic versus lower thoracic upper instrumented vertebrae endpoints have similar outcomes and complications in adult scoliosis. Spine (Phila Pa 1976). 2014;39(13):E795E799.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Virk S, Platz U, Bess S, et al. Factors influencing upper-most instrumented vertebrae selection in adult spinal deformity patients: qualitative case-based survey of deformity surgeons. J Spine Surg. 2021;7(1):3747.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Chou D, Mummaneni P, Anand N, et al. Treatment of the fractional curve of adult scoliosis with circumferential minimally invasive surgery versus traditional, open surgery: an analysis of surgical outcomes. Global Spine J. 2018;8(8):827833.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Fischer CR, Kim Y. Selective fusion for adolescent idiopathic scoliosis: a review of current operative strategy. Eur Spine J. 2011;20(7):10481057.

  • 30

    Ishikawa K, Nakao Y, Oguchi F, Toyone T, Sano S. Thoracic reciprocal change can be predicted before surgery in adult spinal deformity. Global Spine J. 2021;11(8):12301237.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Anand N, Alayan A, Agrawal A, Kahwaty S, Nomoto E, Khandehroo B. Analysis of spino-pelvic parameters and segmental lordosis with L5-S1 oblique lateral interbody fusion at the bottom of a long construct in circumferential minimally invasive surgical correction of adult spinal deformity. World Neurosurg. 2019;130:e1077e1083.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Anand N, Cohen RB, Cohen J, Kahndehroo B, Kahwaty S, Baron E. The influence of lordotic cages on creating sagittal balance in the CMIS treatment of adult spinal deformity. Int J Spine Surg. 2017;11(3):23.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Khalsa AS, Eghbali A, Eastlack RK, et al. Resting pain level as a preoperative predictor of success with indirect decompression for lumbar spinal stenosis: a pilot study. Global Spine J. 2019;9(2):150154.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Wang TY, Nayar G, Brown CR, Pimenta L, Karikari IO, Isaacs RE. Bony lateral recess stenosis and other radiographic predictors of failed indirect decompression via extreme lateral interbody fusion: multi-institutional analysis of 101 consecutive spinal levels. World Neurosurg. 2017;106:819826.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Anand N, Kong C, Fessler RG. A staged protocol for circumferential minimally invasive surgical correction of adult spinal deformity. Neurosurgery. 2017;81(5):733739.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Mundis GM Jr, Turner JD, Deverin V, et al. A critical analysis of sagittal plane deformity correction with minimally invasive adult spinal deformity surgery: a 2-year follow-up study. Spine Deform. 2017;5(4):265271.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Anand N, Alayan A, Kong C, et al. Management of severe adult spinal deformity with circumferential minimally invasive surgical strategies without posterior column osteotomies: a 13-year experience. Spine Deform. 2022;10(5):11571168.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Shen FH, Mason JR, Shimer AL, Arlet VM. Pelvic fixation for adult scoliosis. Eur Spine J. 2013;22(Suppl 2):S265-S275.

  • 39

    Jia F, Wang G, Liu X, Li T, Sun J. Comparison of long fusion terminating at L5 versus the sacrum in treating adult spinal deformity: a meta-analysis. Eur Spine J. 2020;29(1):2435.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Decker S, Mayer M, Hempfing A, et al. Flexibility of thoracic kyphosis affects postoperative sagittal alignment in adult patients with spinal deformity. Eur Spine J. 2020;29(4):813820.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 41

    Protopsaltis TS, Diebo BG, Lafage R, et al. Identifying thoracic compensation and predicting reciprocal thoracic kyphosis and proximal junctional kyphosis in adult spinal deformity surgery. Spine (Phila Pa 1976). 2018;43(21):14791486.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 42

    Passias PG, Pierce KE, Williamson TK, et al. Pelvic nonresponse following treatment of adult spinal deformity: influence of realignment strategies on occurrence. Spine (Phila Pa 1976). 2023;48(9):645652.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 43

    Zuckerman SL, Cerpa M, Lenke LG, et al. Patient-reported outcomes after complex adult spinal deformity surgery: 5-year results of the Scoli-RISK-1 study. Global Spine J. 2022;12(8):17361744.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
  • FIG. 1.

    Selection of instrumentation levels. This is a 79-year-old female with an ASD double curve. The patient presented with refractory low-back pain and mild L5 radiculopathy. She had a previous L4–5 transforaminal interbody fusion that fused solidly. Spinopelvic parameters were as follows: PI 60°, LL 20°, PI-LL 40°, PT 48°, C7–SVA +4 cm, TK 10°, T2–L1 coronal Cobb angle 35°, and L1–5 coronal Cobb angle 45°. The central sacral vertical line was balanced. The patient had an obliquely collapsed L5–S1 disc and mild radiculopathy, so the decision was made to include L5–S1 in our deformity correction/instrumentation. We included the entire lumbar Cobb angle (L1–5), and because this was a long fusion construct including L5–S1, we performed pelvic instrumentation. For UIV selection, we go to at least L1 (to include the entire lumbar coronal Cobb angle), but we must reach the caudal-most neutral vertebral body (in this case, T10). Lastly, we checked on CT and MRI to evaluate the disc at T9–10. This disc was healthy, without degeneration or herniation/stenosis. Therefore, our construct was placed from T10 to the pelvis via the senior author’s described CMIS protocol.15

  • FIG. 2.

    Selective CMIS fusion of an ASD double curve. This is the patient from Fig. 1 who underwent CMIS selective fusion from T10 to the pelvis with excellent reciprocal change in the uninstrumented thoracic spine. The patient’s thoracic coronal Cobb angle was reduced to 10°, with TK of 35°. This was performed without the use of osteotomies through an entirely minimally invasive surgical approach.

  • 1

    Glassman SD, Berven S, Bridwell K, Horton W, Dimar JR. Correlation of radiographic parameters and clinical symptoms in adult scoliosis. Spine (Phila Pa 1976). 2005;30(6):682688.

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  • 2

    Schwab FJ, Blondel B, Bess S, et al. Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis. Spine (Phila Pa 1976). 2013;38(13):E803E812.

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  • 3

    Passias PG, Krol O, Passfall L, et al. Three-column osteotomy in adult spinal deformity: an analysis of temporal trends in usage and outcomes. J Bone Joint Surg Am. 2022;104(21):18951904.

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  • 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):4049.

    • PubMed
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  • 5

    Smith JS, Shaffrey CI, Kuntz C IV, Mummaneni PV. Classification systems for adolescent and adult scoliosis. Neurosurgery. 2008;63(3 suppl):1624.

  • 6

    Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am. 2001;83(8):11691181.

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  • 7

    Schwab F, Ungar B, Blondel B, et al. Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976). 2012;37(12):10771082.

    • PubMed
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  • 8

    Obeid I, Berjano P, Lamartina C, Chopin D, Boissière L, Bourghli A. Classification of coronal imbalance in adult scoliosis and spine deformity: a treatment-oriented guideline. Eur Spine J. 2019;28(1):94113.

    • PubMed
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  • 9

    Ogura Y, Gum JL, Soroceanu A, et al. Practical answers to frequently asked questions for shared decision-making in adult spinal deformity surgery. J Neurosurg Spine. 2021;34(2):218227.

    • PubMed
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  • 10

    Han S, Hyun SJ, Kim KJ, Jahng TA, Lee S, Rhim SC. Rod stiffness as a risk factor of proximal junctional kyphosis after adult spinal deformity surgery: comparative study between cobalt chrome multiple-rod constructs and titanium alloy two-rod constructs. Spine J. 2017;17(7):962968.

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    • Export Citation
  • 11

    Ishihara M, Taniguchi S, Adachi T, et al. Rod contour and overcorrection are risk factors of proximal junctional kyphosis after adult spinal deformity correction surgery. Eur Spine J. 2021;30(5):12081214.

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    • Search Google Scholar
    • Export Citation
  • 12

    Chen JW, Longo M, Chanbour H, et al. Cranially directed upper instrumented vertebrae screw angles are associated with proximal junctional kyphosis in adult spinal deformity surgery. Spine (Phila Pa 1976). 2023;48(10):710719.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Ou-Yang D, Moldavsky M, Wessell N, et al. Evaluation of spinous process tethering at the proximal end of rigid constructs: in vitro range of motion and intradiscal pressure at instrumented and adjacent levels. Int J Spine Surg. 2020;14(4):571579.

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    • Search Google Scholar
    • Export Citation
  • 14

    Alshabab BS, Lafage R, Smith JS, et al. Evolution of proximal junctional kyphosis and proximal junctional failure rates over 10 years of enrollment in a prospective multicenter adult spinal deformity database. Spine (Phila Pa 1976). 2022;47(13):922930.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Anand N, Cohen JE, Cohen RB, Khandehroo B, Kahwaty S, Baron E. Comparison of a newer versus older protocol for circumferential minimally invasive surgical (CMIS) correction of adult spinal deformity (ASD)-evolution over a 10-year experience. Spine Deform. 2017;5(3):213223.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Uribe JS, Beckman J, Mummaneni PV, et al. Does MIS surgery allow for shorter constructs in the surgical treatment of adult spinal deformity? Neurosurgery. 2017;80(3):489497.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Mummaneni PV, Park P, Fu KM, et al. Does minimally invasive percutaneous posterior instrumentation reduce risk of proximal junctional kyphosis in adult spinal deformity surgery? A propensity-matched cohort analysis. Neurosurgery. 2016;78(1):101108.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Park P, Wang MY, Lafage V, et al. Comparison of two minimally invasive surgery strategies to treat adult spinal deformity. J Neurosurg Spine. 2015;22(4):374380.

  • 19

    Lak AM, Lamba N, Pompilus F, et al. Minimally invasive versus open surgery for the correction of adult degenerative scoliosis: a systematic review. Neurosurg Rev. 2021;44(2):659668.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Chou D, Mundis G, Wang M, et al. Minimally invasive surgery for mild-to-moderate adult spinal deformities: impact on intensive care unit and hospital stay. World Neurosurg. 2019;127:e649e655.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Mummaneni PV, Park P, Shaffrey CI, et al. The MISDEF2 algorithm: an updated algorithm for patient selection in minimally invasive deformity surgery. J Neurosurg Spine. 2019;32(2):221228.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Daniels AH, Reid DBC, Durand WM, et al. Upper-thoracic versus lower-thoracic upper instrumented vertebra in adult spinal deformity patients undergoing fusion to the pelvis: surgical decision-making and patient outcomes. J Neurosurg Spine. 2020;32(4):600606.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Luo M, Wang P, Wang W, Shen M, Xu G, Xia L. Upper thoracic versus lower thoracic as site of upper instrumented vertebrae for long fusion surgery in adult spinal deformity: a meta-analysis of proximal junctional kyphosis. World Neurosurg. 2017;102:200208.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Fu X, Sun XL, Harris JA, et al. Long fusion correction of degenerative adult spinal deformity and the selection of the upper or lower thoracic region as the site of proximal instrumentation: a systematic review and meta-analysis. BMJ Open. 2016;6(11):e012103.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Ohba T, Koji F, Koyama K, et al. Preoperative radiographic evaluation of thoracic flexibility and compensation for adult spinal deformity surgery. how to select optimal upper instrumented vertebra to prevent proximal junctional kyphosis. Spine (Phila Pa 1976). 2022;47(2):144152.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Kim HJ, Boachie-Adjei O, Shaffrey CI, et al. Upper thoracic versus lower thoracic upper instrumented vertebrae endpoints have similar outcomes and complications in adult scoliosis. Spine (Phila Pa 1976). 2014;39(13):E795E799.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Virk S, Platz U, Bess S, et al. Factors influencing upper-most instrumented vertebrae selection in adult spinal deformity patients: qualitative case-based survey of deformity surgeons. J Spine Surg. 2021;7(1):3747.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Chou D, Mummaneni P, Anand N, et al. Treatment of the fractional curve of adult scoliosis with circumferential minimally invasive surgery versus traditional, open surgery: an analysis of surgical outcomes. Global Spine J. 2018;8(8):827833.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Fischer CR, Kim Y. Selective fusion for adolescent idiopathic scoliosis: a review of current operative strategy. Eur Spine J. 2011;20(7):10481057.

  • 30

    Ishikawa K, Nakao Y, Oguchi F, Toyone T, Sano S. Thoracic reciprocal change can be predicted before surgery in adult spinal deformity. Global Spine J. 2021;11(8):12301237.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Anand N, Alayan A, Agrawal A, Kahwaty S, Nomoto E, Khandehroo B. Analysis of spino-pelvic parameters and segmental lordosis with L5-S1 oblique lateral interbody fusion at the bottom of a long construct in circumferential minimally invasive surgical correction of adult spinal deformity. World Neurosurg. 2019;130:e1077e1083.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Anand N, Cohen RB, Cohen J, Kahndehroo B, Kahwaty S, Baron E. The influence of lordotic cages on creating sagittal balance in the CMIS treatment of adult spinal deformity. Int J Spine Surg. 2017;11(3):23.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Khalsa AS, Eghbali A, Eastlack RK, et al. Resting pain level as a preoperative predictor of success with indirect decompression for lumbar spinal stenosis: a pilot study. Global Spine J. 2019;9(2):150154.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Wang TY, Nayar G, Brown CR, Pimenta L, Karikari IO, Isaacs RE. Bony lateral recess stenosis and other radiographic predictors of failed indirect decompression via extreme lateral interbody fusion: multi-institutional analysis of 101 consecutive spinal levels. World Neurosurg. 2017;106:819826.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Anand N, Kong C, Fessler RG. A staged protocol for circumferential minimally invasive surgical correction of adult spinal deformity. Neurosurgery. 2017;81(5):733739.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Mundis GM Jr, Turner JD, Deverin V, et al. A critical analysis of sagittal plane deformity correction with minimally invasive adult spinal deformity surgery: a 2-year follow-up study. Spine Deform. 2017;5(4):265271.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Anand N, Alayan A, Kong C, et al. Management of severe adult spinal deformity with circumferential minimally invasive surgical strategies without posterior column osteotomies: a 13-year experience. Spine Deform. 2022;10(5):11571168.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Shen FH, Mason JR, Shimer AL, Arlet VM. Pelvic fixation for adult scoliosis. Eur Spine J. 2013;22(Suppl 2):S265-S275.

  • 39

    Jia F, Wang G, Liu X, Li T, Sun J. Comparison of long fusion terminating at L5 versus the sacrum in treating adult spinal deformity: a meta-analysis. Eur Spine J. 2020;29(1):2435.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Decker S, Mayer M, Hempfing A, et al. Flexibility of thoracic kyphosis affects postoperative sagittal alignment in adult patients with spinal deformity. Eur Spine J. 2020;29(4):813820.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 41

    Protopsaltis TS, Diebo BG, Lafage R, et al. Identifying thoracic compensation and predicting reciprocal thoracic kyphosis and proximal junctional kyphosis in adult spinal deformity surgery. Spine (Phila Pa 1976). 2018;43(21):14791486.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 42

    Passias PG, Pierce KE, Williamson TK, et al. Pelvic nonresponse following treatment of adult spinal deformity: influence of realignment strategies on occurrence. Spine (Phila Pa 1976). 2023;48(9):645652.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 43

    Zuckerman SL, Cerpa M, Lenke LG, et al. Patient-reported outcomes after complex adult spinal deformity surgery: 5-year results of the Scoli-RISK-1 study. Global Spine J. 2022;12(8):17361744.

    • PubMed
    • Search Google Scholar
    • Export Citation

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