Anterior column realignment (ACR) for focal kyphotic spinal deformity using an anterior to psoas approach and anterior longitudinal ligament release

Introduction

Sagittal balance is essential for the success of adult spinal deformity surgery (ASD), and its restoration has been linked to improved health-related quality of life outcomes (1). However, traditional methods for correcting kyphotic deformities, such as three-column osteotomy and vertebrectomy, are associated with significant morbidity, including prolonged operative times, neurological complications, high rates of blood loss, perioperative complications and increased likelihood of revision surgery (2,3).

Recently, anterior column realignment (ACR) with release of the anterior longitudinal ligament (ALL) has been introduced as a powerful alternative to achieve adequate restoration of sagittal alignment (4). The lateral transpsoas approach has been mainly described in the literature for this procedure, but it has limitations such as the need for dissection through the psoas muscle, risk of injury to the lumbar plexus, and inadequate visualization of the great vessels during ALL release (4-6).

The anterior-to-psoas (ATP) approach to the lumbar spine has been proposed as an alternative to the transpsoas approach for approaching the disc space without dissecting through the psoas muscle, thus decreasing the risk of injury to the lumbar plexus (7). However, the ATP approach has its limitations including risks of injury to the sympathetic nerves and the great vessels (7). Nevertheless, when performing an ACR, the ATP approach confers the benefit of direct visualization and protection of the great vessels during the ALL release.

Although a recent study demonstrated the radioanatomic feasibility of performing a complete ALL release and ACR using the ATP approach at the L1–L5 levels, to our knowledge, there are no prior studies that evaluates the clinical application of this technique (8). Thus, the objective of this study was to describe and evaluate the safety of ACR using an ATP approach with complete release of ALL and annulus for correction of focal kyphotic lumbar deformity. We hypothesized that ACR can be performed with a complete ALL release under direct visualization using the ATP approach and can be a safe and effective method for achieving substantial correction of a focal kyphotic deformity within the lumbar spine. We present this article in accordance with the STROBE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-23-84/rc).

Methods

Patient selection

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the institutional review board of Houston Methodist Hospital (No. PRO00032736) and individual consent for this retrospective analysis was waived.

A retrospective analysis of fourteen consecutive patients at a single institution between January 2017 and December 2019 of patients undergoing ACR using an ATP approach for lumbar flatback syndrome and a focal kyphotic deformity by a single surgeon was performed. Primary outcome measures were pre- and postoperative radiographic parameters. Secondary outcome measures were perioperative adverse events (AEs), 30-day readmissions/reoperations, discharge disposition, post-operative length of stay (LOS), and radiographic complications.

Surgical technique

Preoperative planning

During preoperative planning for adult spinal deformity surgery, full-length standing, cross-table lateral spine flexion, and hyperextension radiographs was obtained to evaluate the flexibility of the apical intervertebral disk. In addition to radiographic imaging, a computed tomography (CT) myelogram or magnetic resonance imaging (MRI) was used to evaluate the feasibility of performing an ACR using the ATP approach as previously described.

ACR using ATP approach

All surgical procedures were performed by a single fellowship-trained orthopedic spine surgeon. Each patient was placed in a right lateral decubitus position on a Jackson spinal surgery table under general anesthesia. A pre-incisional localization was completed with anteroposterior (AP) and lateral fluoroscopic views. A retroperitoneal approach was carried out with a 3–4 cm oblique incision centered over the target disc. The ATP corridor was identified under direct visualization. Careful mobilization and anterior retraction of the great vessels and posterior retraction of the psoas muscle was performed. Steinmann pins were placed within the vertebral bodies to maintain complete exposure of the target disc space. The disc preparation and bilateral annulus resection was completed using a combination of a 15-blade scalpel, Cobb elevators, osteotomes, and pituitaries. The endplates were prepared for fusion using rasps and sequential interbody trials with particular care taken for bony endplate preservation. The ALL was released in its entirety using a 15-blade scalpel or reverse angle curette with the great vessels gently retracted under direct visualization. An appropriately sized lordotic cage packed with cancellous allograft and recombinant human bone morphogenetic protein-2 (RhBMP-2) was placed while protecting the anterior structures. Supplemental anterior instrumentation was used for one patient (Patient #8) who underwent an L3 partial corpectomy after obtaining a 42.9-degree correction at L2–L3. Supplemental anterior fixation using a flanged cage was used for one patient (Patient #10) after obtaining a 20.0-degree correction at L4–L5.

Posterior procedure

Upon completion of the anterior procedure, the posterior procedure was completed in a staged fashion at a later day with the exception of one patient (Patient #5). An additional grade 1 posterior column osteotomy (PCO) was performed at the level of the ACR as described by Schwab et al. (9). Thorough decortication of the fusion bed in preparation for a posterolateral fusion was completed and pedicle screw instrumentation was placed.

Thromboembolic protocol

Perioperative tranexamic acid was administered at a loading dose of 30 mg/kg followed by a 3 mg/kg/h infusion. Early mobilization, compression stockings and pneumatic sequential compression devices were used for deep vein thrombosis (DVT) prophylaxis. Prophylactic anticoagulation was not routinely used; instead, routine postoperative lower extremity duplex ultrasound was performed on all patients prior to discharge and at the first follow up visit. Patients received therapeutic anticoagulation if a DVT is found.

Radiographic evaluation

The disk lordotic angle, anterior disk height, and posterior disk height were measured on standing lateral lumbar radiographs for each operated disk preoperatively, postoperatively, and at final follow-up. The disk lordotic angle was calculated as the angle between the caudal endplate of the cranial vertebra and the cranial endplate of the caudal vertebra as previously described (3). On the standing scoliosis radiographs, sagittal parameters including sagittal vertical axis (SVA), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and lumbar lordosis (LL) were measured before surgery, immediately after surgery, and at the final follow-up. Fusion grade was evaluated using a previously described method (10). A grade 1 fusion was defined as fusion with remodeling and trabeculae present, grade 2 for intact graft but not fully remodeled and incorporated with no lucency present, grade 3 for intact graft with lucency surrounding the graft, and grade 4 for absence of fusion with collapse or resorption of the graft (10). Grades 1 and 2 were considered successful fusion within this study. Cage subsidence was defined as a cage sinking into an adjacent vertebral body by >2 mm, based on comparisons with previous radiographs, and was evaluated using postoperative and serial follow-up radiographs. Proximal junctional kyphosis (PJK) was defined as a proximal junctional angle (PJA) magnitude of ≤−28° or a change of ≤−22° measured between the upper instrumented vertebrae −1 (UIV−1) and UIV+2 as recently re-defined by Lovecchio et al. (11). Proximal junctional failure (PJF) was defined as symptomatic PJK requiring revision surgery. All radiological measurements were carried out by a single spinal surgeon who was not involved in patient care.

Statistical analysis

Data analysis was performed using SPSS statistical software (Version 25.0; SPSS, Inc., Chicago, IL, USA). Descriptive statistics were presented using mean ± standard deviation (SD) for continuous variables and frequencies (%) for categorical variables. Two-tailed student t-test was used to analyze continuous data and the Chi-Square or Fisher’s exact test was used to analyze categorical data. The Mann-Whitney U test was utilized for continuous variables with non-normal distribution. A P value <0.05 was considered statistically significant.

Results

Patient demographics

Fourteen consecutive patients (mean age 67.0±3.9 years, 8 males, 6 females, mean follow-up 34.0±23.4 months) with 15 total ACR levels were included in the study (Table 1).

All patients had a history of flatback syndrome and a focal kyphotic deformity within the lumbar spine. A grade 1 PCO with posterior instrumentation was performed at all ACR levels. L2–L3 ACR was performed in nine patients, L3–L4 in four patients, and L4–L5 in two patients. Mean estimated blood loss (EBL) for the anterior procedure was 356±371 mL. Mean EBL for the posterior procedure was 761±627 mL. Mean total EBL was 1,097±992 mL.

Radiographic outcomes

Mean preoperative lumbar lordosis was 22.7°±18.4° (Table 2). Mean lumbar lordosis immediately after surgery and at final follow-up was 50.6°±13.4° (P<0.001) and 48.7°±14.8° (P<0.001), respectively. Mean increase in postoperative lumbar lordosis was 26.0°±12.2° at final follow-up. Mean decrease in PT and increase in SS was 5.5±6.1° and 7.2°±6.3°, respectively at final follow-up.

Mean preoperative disk lordotic angle at the ACR level was 5.4°±5.9° of kyphosis (Table 3). Mean disk lordotic angle immediately after surgery and at final follow-up was 20.6°±6.3° (P<0.001) and 18.7°±5.3° (P<0.001) of lordosis, respectively. Mean increase in postoperative disk lordotic angle was 24.0°±8.5° at final follow-up. Mean preoperative anterior disc height at the ACR level was 1.9±1.7 mm with a mean increase of 14.4±4.3 mm at final follow-up. Mean preoperative posterior disc height was 4.3±2.3 mm with a mean increase of 0.8±2.3 mm at final follow-up.

All patients had a successful grade 1 or grade 2 fusion at the ACR level at final follow-up (Table 4). Thirteen patients (92.9%) had a grade 1 fusion and one patient (7.1%) had a grade 2 fusion at 4-month final follow-up. One patient (7.1%) had post-operative subsidence of the cage. This same patient experienced PJK and PJF requiring revision extension at a follow-up of 56 months. No other patients experienced PJK or PJF using the most recently described definition (11). There were no cases of pseudarthrosis or instrumentation failure.

Functional outcomes

Thirteen patients (92.9%) reported improvement in pain and mobility at final mean follow-up of 34.0±23.4 months. There were no cases of new lower extremity paresis, paresthesia, or increased lower extremity pain post-operatively including thigh pain or pain with hip flexion. One patient (7.1%) experienced increasing back pain starting 51 months post-operatively and underwent revision extension at a follow-up of 56 months due to PJK and PJF as described previously.

AEs

Nine patients (63.4%) experienced one or more perioperative AEs (Table 5). The mean LOS was 9.1±2.9 days. There was one case of 30-day re-admission due to the development of a small pulmonary embolus, which was successfully treated with therapeutic anticoagulation. There were no cases of 30-day reoperations. Seven patients were discharged home, six patients were discharged to a rehabilitation facility, and one patient to a skilled nursing facility. Post-operative acute kidney injury (AKI) was the most common AE with four cases followed by, three cases of anemia requiring transfusion, two DVTs, and one case each of urinary tract infection, pulmonary embolism, pneumonia, and ileus requiring temporary nasogastric tube (NGT) and bowel rest.

Discussion

This study aimed to describe and assess the safety of ACR using an ATP approach with complete release of the ALL and annulus for correcting a focal kyphotic lumbar deformity in patients with lumbar flatback syndrome. This technique allowed a mean increase of disk lordotic angle of 24.0°±8.5° at a final follow-up of 34.0±23.4 months without major intraoperative complications or 30-day reoperations. We reported a 100% successful fusion rate and one case of post-operative subsidence and PJK requiring revision extension of the fusion construct. Overall, these results were similar to a recent study reporting a modified ACR technique using the ATP approach with a partial release of the ALL (12). Using a partial ALL release, Jeon et al. demonstrated an overall increase in disk lordotic angle of 15.8°±6.7° at a final follow-up of 42.6±14.5 months when combining with a grade 2 PCO (12). The same authors were able to achieve an overall increase in disk lordotic angle of 17.9°±6.2° when combining the modified ACR with a pedicle subtraction osteotomy (PSO). Our study demonstrates that by performing a complete release of the ALL combined with a grade 1 PCO, a larger degree of correction was possible.

Although an ACR is a powerful tool for achieving sagittal deformity correction, it is critical to appreciate spinal deformity principles prior to its use as prior studies have shown the importance of maintaining a majority of the lumbar lordosis at L4–L5 and L5–S1 (13-15). Patients presenting with flatback syndrome and minimal L4–S1 lordosis should avoid relying solely on an upper lumbar spine ACR to prevent complications at the proximal junction. In our patient cohort, 85.7% underwent ACR at either L2–L3 or L3–L4, but this procedure was strictly indicated for those with a rigid focal kyphotic deformity. Furthermore, these upper lumbar ACRs were supplemented with lower lumbar ALIFs when indicated (Figure 1, Table 1). The mean preoperative disk angle in the current study was 5.4°±5.9° of kyphosis. This is in comparison to Jeon et al.’s patient cohort with a mean preoperative disk lordotic angle of 0.4°±5.9° of lordosis who underwent a modified ACR with a grade 2 PCO (12). Thus, a modified ACR with partial release of the ALL is likely more appropriate for this patient cohort as performing a complete ALL release and achieving a larger lordosis correction may have led to an overcorrection in these deformities.

Figure 1 A 67-year-old male (case #9) with a prior L4–L5 TLIF who presented with severe sagittal imbalance due to flatback syndrome, adjacent segment disease, and an L2–L3 focal kyphotic deformity. A two-staged L2–L3 ACR, L5–S1 ALIF, grade 2 PCOs at L1–L2, L2–L3, L5–S1, and T11-pelvis PSIF was performed. (A,B) preoperative PA and lateral standing radiographs demonstrating a positive sagittal imbalance with a C7 SVA of 130 mm, LL of 37°, PI of 67°, and PT of 36°; (C,D) postoperative radiographs at 36-month follow-up demonstrating a C7 CVA of 5 mm, LL of 65°, PI of 74°, and PT of 29°. (E) Preoperative L2–L3 disk lordotic angle with 0.5° of kyphosis. (F) Postoperative L2–L3 disk lordotic angle of 26.0° of lordosis. SVA, sagittal vertical axis; LL, lumbar lordosis; PI, pelvic incidence; PT, pelvic tilt; IDA, intradiscal angle; TLIF, transforaminal lumbar interbody fusion; ACR, anterior column realignment; ALIF, anterior lumbar interbody fusion; PCO, posterior column osteotomy; PSIF, posterior spinal instrumented fusion; PA, posteroanterior.

In all presented cases, the surgeon was able to completely visualize the ALL with gentle retraction of the great vessels prior to performing the ALL release. Therefore, in comparison with the original ACR technique using a transpsoas approach, the authors believe that performing an ACR using the ATP approach may be a safer technique when radioanatomically feasible. A prior study by Hirase et al. described the radioanatomic feasibility of performing an ACR using an ATP approach at L1–L5 and found that performing this technique was considered high risk (high-rising psoas or no measurable space between the ALL and the great vessels) in 13.0% of patients at the L2–L3 level, 40.7% at the L3–L4 level, and 89.0% at the L4–L5 level (8). The majority of the patients within our cohort underwent an ACR using an ATP approach were at the L2–L3 or L3–L4 level, largely due to the location of the focal kyphotic deformity and radioanatomic feasibility as presented by Hirase et al. (8).

Traditionally, a PJK was defined as a kyphotic change in the PJA of at least 10°. However, this definition was found by multiple studies to lack correlation with clinical outcomes (16-19). Lovecchio et al. recently proposed a new definition of PJK as a magnitude of ≤−28° or a change of ≤−22° measured between UIV−1 and UIV+2 and found that these cut-off values best predict the need revision surgery for PJK (11). One patient within our patient cohort met these criteria, which was also the same patient that required a revision extension of the fusion construct due to PJK/PJF. Our 100% fusion rate and 7.1% cage subsidence rates were also similar to the modified ACR using an ATP approach as presented by Jeon et al. who reported a 94.6% and 8.9% fusion and subsidence rates, respectively (12).

Our study demonstrated a favorable safety profile, with no intraoperative major complications or 30-day reoperations. However, we found a high rate of perioperative medical AEs with nine patients (63.4%) experiencing one or more perioperative AEs (Table 5). The likely reason for these AEs is multifactorial. First, 13 of our 14 included patients were revision surgeries which have been shown to be associated with higher rates of perioperative AEs (20,21). All 13 of these patients were included within our sarcopenic cohort in our prior study that reported the association of sarcopenia with perioperative AEs after complex revision thoracolumbar spine surgeries (22). This study found that sarcopenic patients had a 75.5% rate of AEs compared to 27.7% in the non-sarcopenic group (22). Unfortunately, these patients with a prior lumbar fusion presenting with severe sagittal imbalance and flatback syndrome are largely disabled, immobile, and sarcopenic. Thus, particularly for this patient population, it is critical to offer adequate preoperative counseling regarding postoperative expectations in terms of preparing for AEs and the appropriate methods to treat each AE.

Our study has several limitations that should be acknowledged. Firstly, the retrospective, non-randomized nature of our investigation means that the accuracy of the data is dependent on the accuracy of the medical records and may also be prone to selection bias. However, our indications for this surgical technique were standardized to minimize selection bias. Additionally, our study only involved data from a single surgeon at a single institution, which may not be generalizable to other surgeons or centers that employ different surgical techniques or management strategies. Furthermore, our study had a relatively small sample size, which may have resulted in insufficient statistical power to identify certain associations. Finally, our institution did not utilize patient-reported outcome scores, which did not allow an objective measurement of post-operative functional outcomes. However, all outcomes were described in terms of subjective improvement in pain and mobility post-operatively at final follow-up and objective neurologic examination data was obtained and documented.

Despite these limitations, our study represents the most comprehensive investigation to date of the safety of ACR using an ATP approach with release of ALL and bilateral annulus for correction of a focal kyphotic lumbar deformity. To our knowledge, this is the largest study of its kind, and we believe that it provides valuable insights into the effectiveness and safety of this surgical technique. However, it is important to note that additional studies are needed to confirm the external validity of our findings before they can be applied in clinical practice. By addressing the limitations of our study and building upon its findings, future investigations can help to further elucidate the potential benefits and risks of ACR using an ATP approach with release of ALL and bilateral annulus for correction of a focal kyphotic lumbar deformity.

Conclusions

ACR can be performed with a complete ALL release under direct visualization using the ATP approach. This technique can be a safe and effective method for achieving substantial correction of a focal kyphotic deformity within the lumbar spine.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-23-84/rc

Data Sharing Statement: Available at https://jss.amegroups.com/article/view/10.21037/jss-23-84/dss

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-23-84/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-23-84/coif). RAWM reports that he is a paid presenter and speaker of DePuy, A Johnson & Johnson Company, and received IP royalties from Globus Medical. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by institutional review board of Houston Methodist Hospital (No. PRO00032736) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Schwab F, Patel A, Ungar B, et al. Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery. Spine (Phila Pa 1976) 2010;35:2224-31. [Crossref] [PubMed]
2. Quarto E, Zanirato A, Ursino C, et al. Adult spinal deformity surgery: posterior three-column osteotomies vs anterior lordotic cages with posterior fusion. Complications, clinical and radiological results. A systematic review of the literature. Eur Spine J 2021;30:3150-61. [Crossref] [PubMed]
3. Smith JS, Shaffrey CI, Klineberg E, et al. Complication rates associated with 3-column osteotomy in 82 adult spinal deformity patients: retrospective review of a prospectively collected multicenter consecutive series with 2-year follow-up. J Neurosurg Spine 2017;27:444-57. [Crossref] [PubMed]
4. Akbarnia BA, Mundis GM Jr, Moazzaz P, et al. Anterior column realignment (ACR) for focal kyphotic spinal deformity using a lateral transpsoas approach and ALL release. J Spinal Disord Tech 2014;27:29-39. [Crossref] [PubMed]
5. Turner JD, Akbarnia BA, Eastlack RK, et al. Radiographic outcomes of anterior column realignment for adult sagittal plane deformity: a multicenter analysis. Eur Spine J 2015;24:427-32. [Crossref] [PubMed]
6. Saigal R, Mundis GM Jr, Eastlack R, et al. Anterior Column Realignment (ACR) in Adult Sagittal Deformity Correction: Technique and Review of the Literature. Spine (Phila Pa 1976) 2016;41:S66-S73. [Crossref] [PubMed]
7. Woods KR, Billys JB, Hynes RA. Technical description of oblique lateral interbody fusion at L1-L5 (OLIF25) and at L5-S1 (OLIF51) and evaluation of complication and fusion rates. Spine J 2017;17:545-53. [Crossref] [PubMed]
8. Hirase T, Shin C, Thirumavalavan J, et al. Anterior Column Realignment Using an Anterior-To-Psoas Approach: A Radiographic-Anatomic Feasibility Study at L1-L5. Global Spine J 2023; Epub ahead of print. [Crossref]
9. Schwab F, Blondel B, Chay E, et al. The comprehensive anatomical spinal osteotomy classification. Neurosurgery 2014;74:112-20; discussion 120. [Crossref] [PubMed]
10. Bridwell KH, Lenke LG, McEnery KW, et al. Anterior fresh frozen structural allografts in the thoracic and lumbar spine. Do they work if combined with posterior fusion and instrumentation in adult patients with kyphosis or anterior column defects?. Spine (Phila Pa 1976) 1995;20:1410-8.
11. Lovecchio F, Lafage R, Line B, et al. Optimizing the Definition of Proximal Junctional Kyphosis: A Sensitivity Analysis. Spine (Phila Pa 1976) 2023;48:414-20. [Crossref] [PubMed]
12. Jeon JM, Chung HW, Lee HD, et al. A Modified Anterior Column Realignment With Partial Anterior Longitudinal Ligament Release in Oblique Lateral Interbody Fusion. Spine (Phila Pa 1976) 2022;47:1583-9. [Crossref] [PubMed]
13. Roussouly P, Gollogly S, Berthonnaud E, et al. Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position. Spine (Phila Pa 1976) 2005;30:346-53. [Crossref] [PubMed]
14. Laouissat F, Sebaaly A, Gehrchen M, et al. Classification of normal sagittal spine alignment: refounding the Roussouly classification. Eur Spine J 2018;27:2002-11. [Crossref] [PubMed]
15. Glattes RC, Bridwell KH, Lenke LG, et al. Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion: incidence, outcomes, and risk factor analysis. Spine (Phila Pa 1976) 2005;30:1643-9. [Crossref] [PubMed]
16. Kim YJ, Bridwell KH, Lenke LG, et al. Proximal junctional kyphosis in adult spinal deformity after segmental posterior spinal instrumentation and fusion: minimum five-year follow-up. Spine (Phila Pa 1976) 2008;33:2179-84. [Crossref] [PubMed]
17. 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;37:1479-89. [Crossref] [PubMed]
18. Sebaaly A, Sylvestre C, El Quehtani Y, et al. Incidence and Risk Factors for Proximal Junctional Kyphosis: Results of a Multicentric Study of Adult Scoliosis. Clin Spine Surg 2018;31:E178-E183. Correction appears in Clin Spine Surg 2018;31:184.
19. Kim SS, Michelsen CB. Revision surgery for failed back surgery syndrome. Spine (Phila Pa 1976) 1992;17:957-60. [Crossref] [PubMed]
20. Fritsch EW, Heisel J, Rupp S. The failed back surgery syndrome: reasons, intraoperative findings, and long-term results: a report of 182 operative treatments. Spine (Phila Pa 1976) 1996;21:626-33. [Crossref] [PubMed]
21. Sansur CA, Smith JS, Coe JD, et al. Scoliosis research society morbidity and mortality of adult scoliosis surgery. Spine (Phila Pa 1976) 2011;36:E593-7. [Crossref] [PubMed]
22. Hirase T, Haghshenas V, Bratescu R, et al. Sarcopenia predicts perioperative adverse events following complex revision surgery for the thoracolumbar spine. Spine J 2021;21:1001-9. [Crossref] [PubMed]