Comparison of multilevel low-grade techniques versus three-column osteotomies in adult spinal deformity surgery: does harmonious correction matter?

OBJECTIVE

Recent debate has arisen between whether to use a three-column osteotomy (3CO) or multilevel low-grade (MLG) techniques to treat severe sagittal malalignment in adult spinal deformity (ASD) surgery. The goal of this study was to compare the outcomes of 3CO and MLG techniques performed in corrective surgeries for ASD.

METHODS

ASD patients who had a baseline PI-LL > 30° and 2-year follow-up data were included. Patients underwent either 3CO or MLG (thoracolumbar posterior column osteotomies at ≥ 3 levels or anterior lumbar interbody fusion at ≥ 3 levels with no 3CO). The segmental utility ratio was used to assess relative segmental correction (segmental correction divided by overall correction in lordosis divided by the number of thoracolumbar interventions [interbody fusion, thoracolumbar posterior column osteotomies, and 3CO]). The paired t-test was used to assess lordotic distribution by differences in lordosis between adjacent lumbar disc spaces (e.g., L1-2 to L2-3). Multivariate analysis, controlling for age, sex, BMI, osteoporosis, baseline pelvic incidence, and T1 pelvic angle, was used to evaluate the complication rates and radiographic and patient-reported outcomes between the groups.

RESULTS

A total of 93 patients were included, 53% of whom underwent MLG and 47% of whom underwent 3CO. The MLG group had a lower BMI (p < 0.05). MLG patients received fewer previous fusions than 3CO patients (31% vs 80%, p < 0.001). MLG patients had 24% less blood loss but a 22% longer operative time (565 vs 419 minutes, p = 0.008). Using adjusted analysis, the 3CO group had greater segmental and relative correction at each level (segmental utility ratio mean 69% for 3CO vs 23% for MLG, p < 0.001). However, the 3CO group had lordotic differences between two adjacent lumbar disc pairs (range -0.5° to 9.0°, p = 0.009), while MLG was more harmonious (range 2.2°-6.5°, p > 0.4). MLG patients were more likely to undergo realignment to age-adjusted standards (OR 5.6, 95% CI 1.2-46.4; p = 0.033). MLG patients were less likely to develop neurological complications or undergo reoperation (OR 0.4, 95% CI 0.1-0.9; p = 0.041). Adjusted analysis revealed that MLG patients more often met a substantial clinical benefit in the Oswestry Disability Index score (OR 5.3, 95% CI 1.1-26.8; p = 0.043).

CONCLUSIONS

MLG techniques showed better utility in lumbar distribution and age-adjusted global correction while minimizing neurological complications and reoperation rates by 2 years postoperatively. In selected instances, these techniques may offer the spine deformity surgeon a safer alternative when correcting severe adult spinal deformity.

The lower Osteotomy Level is Associated With Decreased Revision Surgery Due to Mechanical Complications After Three-Column Osteotomy in Patients With Adult Spinal Deformity: A Multi-Institutional Retrospective Study

STUDY DESIGN

A multi-institutional retrospective study.

OBJECTIVES

To investigate risk factors of mechanical failure in three-column osteotomy (3COs) in patients with adult spinal deformity (ASD), focusing on the osteotomy level.

METHODS

We retrospectively reviewed 111 patients with ASD who underwent 3COs with at least 2 years of follow-up. Radiographic parameters, clinical data on early and late postoperative complications were collected. Surgical outcomes were compared between the low-level osteotomy group and the high-level osteotomy group: osteotomy level of L3 or lower group (LO group, n = 60) and osteotomy of L2 or higher group (HO group, n = 51).

RESULTS

Of the 111 patients, 25 needed revision surgery for mechanical complication (mechanical failure). A lower t-score (odds ratio [OR] .39 P = .002) and being in the HO group (OR 4.54, P = .03) were independently associated with mechanical failure. In the analysis divided by the osteotomy level (LO and HO), no difference in early complications or neurological complications was found between the two groups. The rates of overall mechanical complications, rod failure, and mechanical failure were significantly higher in the HO group than in the LO group. After propensity score matching, mechanical complications and failures were still significantly more observed in the HO group than in the LO group (P = .01 and .029, respectively).

CONCLUSIONS

A lower t-score and osteotomy of L2 or higher were associated with increased risks of mechanical failure. Lower osteotomy was associated with better correction of sagittal balance and a lower rate of mechanical complications.

The role of multi-modal intra-operative neurophysiological monitoring in corrective surgeries for thoracic tuberculosis with kyphosis

OBJECTIVE

The aim of this study was to assess the performance and utility of motor evoked potentials (MEP) and somatosensory evoked potentials (SSEP) during corrective surgery for thoracic tuberculosis with kyphosis (TTK).

METHODS

68 patients (mean age 31.7 ± 20.3 years) who underwent corrective surgery for TTK from 2012 to 2019 were included in this retrospective study. Patients were neurologicaly evaluated before and after surgery with systematic neurologic examinations. Intraoperative neurophysiological monitoring (IONM) with SSEP and MEP was carried out. A receiver operating characteristic (ROC) curve and area under ROC curve (AUC) were used to identify the diagnostic accuracy of potential recovery.

RESULTS

IONM alerting occurred in 12 surgeries (12/68, 17.6%), of which 6 were SSEP alerting, 2 MEP alerting, and 4 combinations of both SSEP and MEP. Among the 12 cases where there was IONM alerting, 3 (25%) had postoperative neurological deficits(PND), whereas one patient had PND without IONM alerting. IONM sensitivity and specificity were 0.75 (95% CI 0.22-0.99) and 0.86 (95% CI 0.74-0.93) respectively. Positive predictive value (PPV) and negative predictive value (NPV) were 0.25 and 0.98 respectively. The AUC of evoked potential recovery in diagnosing PND was 0.884.

CONCLUSION

Our study showed that multi-modal IONM with SSEP and MEP can effectively indicate a potential neural injury and predict PND during TTK corrective surgery.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Posterior Three-column Osteotomy for Treatment of Congenital Kyphosis with Multiple Thoracolumbar/lumbar (TL/L) Anterior Unsegmented Vertebrae (AUVs): A Comparison between Patients with Increasing Number of AUVs

BACKGROUND

Three-column osteotomy (3-CO) is sometimes challenging when confronting many anterior unsegmented vertebrae in congenital kyphosis (CK-AUVs).

OBJECTIVE

To compare the surgical outcomes of single level 3-CO and the associated complications between CK with increasing number of AUVs.

METHODS

25 consecutive operated patients with CK-AUVs at a mean age of 16.2±10.3 years were retrospectively reviewed. They were stratified into two groups according to the number of AUVs: 3-AUVs group and ≥4 AUVs group. The osteotomy types, surgical outcomes and the related complications were analyzed and compared between the two groups.

RESULTS

13 and 12 patients were recruited in the 3-AUVs group and the ≥4 AUVs group, respectively. The ratio of Pedicle Subtraction Osteotomy, Grade IV osteotomy, Vertebra Column Resection and Vertebral Column Decancellation were 15.4%, 38.5%, 46.1% and 0% for 3-AUVs group and 8.3%, 0%, 83.3% and 8.3% for ≥4 AUVs group, respectively. Preoperative focal kyphosis was significantly higher in the ≥4 AUVs group (82.9±28° vs.59.7±9.4°, p=0.010), which was remarkably corrected in both groups postoperatively. While ≥4 AUVs group had a significantly higher remaining kyphosis (33.6±13.4° vs. 15.1±9.1°, p<0.001) with a significantly lower correction rate (61.2±13.6% vs. 75.0±15.6%, p=0.001). The complication rate was significantly higher in ≥4 AUVs group than 3-AUVs group (8/12 vs. 1/13, p=0.004), mainly involving vertebral subluxation and proximal junctional kyphosis.

CONCLUSIONS

Posterior single-level grade Ⅲ-Ⅴ 3-CO can achieve satisfactory kyphosis correction in CK with 3 AUVs. Decreasing kyphosis correction and increasing surgery-related complications are prone to develop when treating CK with ≥4 AUVs.

Usefulness of anterior column release for segmental lordosis restoration in degenerative lumbar kyphosis

OBJECTIVE

Three-column osteotomies (3COs) for surgical correction of lumbar kyphosis show a strong correction capacity, but this procedure carries high morbidity rates. The anterior column release (ACR) technique was developed as a less invasive procedure. In this study the authors aimed to evaluate sagittal alignment restoration using ACR and to determine factors that affect the degree of correction.

METHODS

This study included 36 patients (68 cases) who underwent ACR of more than one level for adult spinal deformity. Parameters for regional sagittal alignment included segmental lordosis (SL). The parameters for global sagittal alignment included pelvic incidence, lumbar lordosis, sacral slope, pelvic tilt, and sagittal vertical axis (SVA). In addition, the interdiscal height (IDH) and difference of interdiscal angle (DIDA) were measured to evaluate the stiffness of the vertebra segment. The changes in SL were evaluated after ACR and the change of global sagittal alignment was also determined. Factors such as the location of the ACR level, IDH, DIDA, cage height, and additional posterior column osteotomy (PCO) were analyzed for correlation with the degree of SL correction.

RESULTS

Thirty-six patients were included in this study. A total of 68 levels were operated with the ACR (8 levels at L2-3, 27 levels at L3-4, and 33 levels at L4-5). ACR was performed for 1 level in 10 patients, 2 levels in 20, and 3 levels in 6 patients (mean 1.9 ± 0.7 levels per patient). Mean follow-up duration was 27.1 ± 4.2 months. The mean SL of the total segment was 0.4° ± 7.2° preoperatively and increased by 15.3° ± 5.5° at the last follow-up (p < 0.001); thus, the mean increase of SL was 14.9° ± 8.1° per one ACR. Global sagittal alignment was also improved following SL restoration with SVA from 101.9 mm to 31.4 mm. The degree of SL correction was correlated with the location of ACR level (p = 0.041) and was not correlated with IDH, DIDA, cage height and additional PCO.

CONCLUSIONS

This study demonstrated that the mean correction angle of SL was 14.9 per one ACR. The degree of disc space collapse and stiffness of segment did not affect the degree of correction by ACR.

Utility of intraoperative neuromonitoring and outcomes of neurological complication in lower cervical and upper thoracic posterior-based three-column osteotomies for cervical deformity

OBJECTIVE

For severe and rigid adult cervical deformity, posterior-based three-column osteotomies (3COs) are warranted, but neurological complications are relatively high with such procedures. The performance measures of intraoperative neuromonitoring (IONM) during cervicothoracic 3CO have yet to be studied, and there remains a paucity of literature regarding the topic. Therefore, the authors of this study examined the performance of IONM in predicting new neurological weakness following lower cervical and upper thoracic 3CO. In addition, they report the 6-month, 1-year, and 2-year outcomes of patients who experienced new postoperative weakness.

METHODS

The authors performed a retrospective review of a single surgeon's experience from 2011 to 2018 with all patients who had undergone posterior-based 3CO in the lower cervical (C7) or upper thoracic (T1-4) spine. Medical and neuromonitoring records were independently reviewed.

RESULTS

A total of 56 patients were included in the analysis, 38 of whom had undergone pedicle subtraction osteotomy and 18 of whom had undergone vertebral column resection. The mean age was 61.6 years, and 41.1% of the patients were male. Among the study cohort, 66.1% were myelopathic and 33.9% had preoperative weakness. Mean blood loss was 1565.0 ml, and length of surgery was 315.9 minutes. Preoperative and postoperative measures assessed were cervical sagittal vertical axis (6.5 and 3.8 cm, respectively; p < 0.001), cervical lordosis (2.3° and -6.7°, p = 0.042), and T1 slope (48.6° and 35.8°, p < 0.001). The complication rate was 49.0%, and the new neurological deficit rate was 17.9%. When stratifying by osteotomy level, there were significantly higher rates of neurological deficits at C7 and T1: C7 (37.5%), T1 (44.4%), T2 (16.7%), T3 (14.3%), and T4 (0.0%; p = 0.042). Most new neurological weakness was the nerve root pattern rather than the spinal cord pattern. Overall, there were 16 IONM changes at any threshold: 14 at 50%, 8 at 75%, and 13 if only counting patients who did not return to baseline (RTB). Performance measures for the various thresholds were accuracy (73.2% to 77.8%), positive predictive value (25.0% to 46.2%), negative predictive value (81.3% to 88.1%), sensitivity (18.2% to 54.5%), and specificity (77.8% to 86.7%). Sensitivity to detect a spinal cord pattern of weakness was 100% and 28.6% for a nerve root pattern of weakness. In patients with a new postoperative deficit, 22.2% were unchanged, 44.4% improved, and 33.3% had a RTB at the 2-year follow-up.

CONCLUSIONS

Complication rates are high following posterior 3CO for cervical deformity. 3CO at C7 and T1 has the highest rates of neurological deficit. Current IONM modalities have modest performance in predicting postoperative deficits, especially for nerve root neuropraxia. A large prospective multicenter study is warranted.

Comprehensive classification system for multirod constructs across three-column osteotomies: a reliability study

OBJECTIVE

In this study, the authors' goal was to determine the intra- and interobserver reliability of a new classification system that allows the description of all possible constructs used across three-column osteotomies (3COs) in terms of rod configuration and density.

METHODS

Thirty-five patients with multirod constructs (MRCs) across a 3CO were classified by two spinal surgery fellows according to the new system, and then were reclassified 2 weeks later. Constructs were classified as follows: the number of rods across the osteotomy site followed by a letter corresponding to the type of rod configuration: "M" is for a main rod configuration, defined as a single rod spanning the osteotomy. "L" is for linked rod configurations, defined as 2 rods directly connected to each other at the osteotomy site. "S" is for satellite rod configurations, which were defined as a short rod independent of the main rod with anchors above and below the 3CO. "A" is for accessory rods, defined as an additional rod across the 3CO attached to main rods but not attached to any anchors across the osteotomy site. "I" is for intercalary rod configurations, defined as a rod connecting 2 separate constructs across the 3CO, without the intercalary rod itself attached to any anchors across the osteotomy site. The intra- and interobserver reliability of this classification system was determined.

RESULTS

A sample estimation for validation assuming two readers and 35 subjects results in a two-sided 95% confidence interval with a width of 0.19 and a kappa value of 0.8 (SD 0.3). The Fleiss kappa coefficient (κ) was used to calculate the degree of agreement between interrater and intraobserver reliability. The interrater kappa coefficient was 0.3, and the intrarater kappa coefficient was 0.63 (good reliability). This scenario represents a high degree of agreement despite a low kappa coefficient. Correct observations by both observers were 34 of 35 and 33 of 35 at both time points. Misclassification was related to difficulty in determining connectors versus anchors.

CONCLUSIONS

MRCs across 3COs have variable rod configurations. Currently, no classification system or agreement on nomenclature exists to define the configuration of rods across 3COs. The authors present a new, comprehensive MRC classification system with good inter- and intraobserver reliability and a high degree of agreement that allows for a standardized description of MRCs across 3COs.

Comparison of perioperative complications following posterior column osteotomy versus posterior-based 3-column osteotomy for correction of rigid cervicothoracic deformity: a single-surgeon series of 95 consecutive cases

OBJECTIVE

The correction of severe cervicothoracic sagittal deformities can be very challenging and can be associated with significant morbidity. Often, soft-tissue releases and osteotomies are warranted to achieve the desired correction. There is a paucity of studies that examine the difference in morbidity and complication profiles for Smith-Petersen osteotomy (SPO) versus 3-column osteotomy (3CO) for cervical deformity correction.

METHODS

A retrospective comparison of complication profiles between posterior-based SPO (Ames grade 2 SPO) and 3CO (Ames grade 5 opening wedge osteotomy and Ames grade 6 closing wedge osteotomy) was performed by examining a single-surgeon experience from 2011 to 2018. Patients of interest were individuals who had a cervical sagittal vertical axis (cSVA) > 4 cm and/or cervical kyphosis > 20° and who underwent corrective surgery for cervical deformity. Multivariate analysis was utilized.

RESULTS

A total of 95 patients were included: 49 who underwent 3CO and 46 who underwent SPO. Twelve of the SPO patients underwent an anterior release procedure. The patients' mean age was 63.2 years, and 60.0% of the patients were female. All preoperative radiographic parameters showed significant correction postoperatively: cSVA (6.2 cm vs 4.5 cm [preoperative vs postoperative values], p < 0.001), cervical lordosis (6.8° [kyphosis] vs -7.5°, p < 0.001), and T1 slope (40.9° and 35.2°, p = 0.026). The overall complication rate was 37.9%, and postoperative neurological deficits were seen in 16.8% of patients. The surgical and medical complication rates were 17.9% and 23.2%, respectively. Overall, complication rates were higher in patients who underwent 3CO compared to those who underwent SPO, but this was not statistically significant (total complication rate 42.9% vs 32.6%, p = 0.304; surgical complication rate 18.4% vs 10.9%, p = 0.303; and new neurological deficit rate 20.4% vs 13.0%, p = 0.338). Medical complication rates were similar between the two groups (22.4% [3CO] vs 23.9% [SPO], p = 0.866). Independent risk factors for surgical complications included male sex (OR 10.88, p = 0.014), cSVA > 8 cm (OR 10.36, p = 0.037), and kyphosis > 20° (OR 9.48, p = 0.005). Combined anterior-posterior surgery was independently associated with higher odds of medical complications (OR 10.30, p = 0.011), and preoperative kyphosis > 20° was an independent risk factor for neurological deficits (OR 2.08, p = 0.011).

CONCLUSIONS

There was no significant difference in complication rates between 3CO and SPO for cervicothoracic deformity correction, but absolute surgical and neurological complication rates for 3CO were higher. A preoperative cSVA > 8 cm was a risk factor for surgical complications, and kyphosis > 20° was a risk factor for both surgical and neurological complications. Additional studies are warranted on this topic.

The Barrow Biomimetic Spine: effect of a 3-dimensional-printed spinal osteotomy model on performance of spinal osteotomies by medical students and interns

Background

The Schwab osteotomy grading scale-a unified osteotomy classification system created in 2014 by Schwab et al.-is one of many concepts in spine surgery that require detailed knowledge of 3-dimensional (3D) anatomy. 3D-printed spine models have demonstrated increasing utility in spine surgery as they more quickly communicate information on complex 3D anatomical relationships than planar imaging or 2-dimensional images. The purpose of this study was to evaluate the utility of a custom, 3D-printed spine model to help surgical trainees understand and perform the Schwab osteotomy grading scale.

Methods

Eight participants were randomized into 2 groups: group 1 received written instructional materials about the Schwab osteotomy grading scale, whereas group 2 received both written materials and a 3D-printed model of the spine with osteotomy regions demarcated. All participants were administered written and practical examinations.

Results

The group randomized to receive the 3D-printed model performed significantly better on both the written assessment (mean score, 7.75±0.50 vs. 5.75±0.50, P=0.023) and the practical examination (mean score, 1.75±0.32 vs. 1.08±0.09, P=0.025) than the group that received only written instructions.

Conclusions

Our results support the conclusion that this 3D-printed spine model is an effective adjunct to help early surgical trainees understand the Schwab osteotomy grading scale. Participants who received the model in addition to the source manuscript demonstrated improved theoretical knowledge and better performance on practical tests of complex spinal osteotomies. Similar models are likely to have utility in surgical training programs and as patient education models.

Risk Factors for 30-Day Readmissions and Reoperations After 3-Column Osteotomy for Spinal Deformity

STUDY DESIGN

Retrospective study of a prospectively collected database.

OBJECTIVE

To investigate the rate and risk factors for 30-day readmissions and reoperations after 3-column osteotomy (3CO).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database (2012-2014) was reviewed. Inclusion criteria were adult patients who underwent 3CO. The rate of 30-day readmission/reoperation was examined, and the association between patient/operative characteristics and outcome was investigated via multivariate analysis.

RESULTS

There were 299 patients who underwent a 3CO for spinal deformity. The rate of 30-day readmission and reoperation was 11.0% and 8.4%, respectively; 7.7% of readmissions were related to the primary procedure and 3.3% were unrelated. The most common unique cause for readmission was wound infection in 27.2% of cases. Among reoperations, the most common unique indications were wound infection (20.0%) and implant-related complications (20.0%). On multivariate analysis, obesity (odds ratio [OR] = 2.96; 95% CI = 1.06-8.25; P = .038), chronic obstructive pulmonary disease (OR = 20.8; 95% CI = 3.49-123.5; P = .001), and fusion of 13 or more spinal levels were independent predictors of readmission (OR = 4.86; 95% CI = 1.21-19.5; P = .025). On the other hand, independent predictors of reoperation included chronic obstructive pulmonary disease (OR = 6.33; 95% CI = 1.16-34.5; P = .033) and chronic steroid use (OR = 6.69; 95% CI = 1.61-27.7; P = .009).

CONCLUSION

Wound complications and short-term implant-related complications are important causes of readmission and/or reoperation after 3CO. Preoperative factors such as obesity, chronic lung disease, chronic steroid use, and long-segment fusion procedures may significantly increase the risk of 30-day morbidity following high-grade osteotomies.

Complications and intercenter variability of three-column resection osteotomies for spinal deformity surgery: a retrospective review of 423 patients

Study Type Retrospective review of a prospectively collected multicenter database.

Introduction Three-column resection osteotomies (3CO), including pedicle subtraction osteotomies and vertebral column resections are performed for correction of sagittal deformity; however, they have high rates of reported complications. This study examined the incidence and intercenter variability of major intraoperative complications (IOC), postoperative complications (POC), and overall complications (IOC + POC) up to 6 weeks postoperation.

Objective The aim of the study is to examine the incidence and intercenter variability of major complications associated with 3CO.

Patients and Methods A retrospective review of patients with 3CO from eight different sites was performed. The incidence and types of complications were determined for the study population (N = 423). The analysis compared patients with one (n = 391) and two (n = 32) osteotomies, as well as patients with a thoracic osteotomy (ThO) (n = 72) versus a lumbosacral osteotomy (LSO) (n = 319) of the spine. Subsequent analysis was performed to compare sites with low-osteotomy volumes (< 50 patients) to sites with large osteotomy volumes (more than 50 patients). Major blood loss (MBL) was defined as more than 4L.

Results Of the 423 patients, the incidence of major IOC, POC, and overall complications was 28, 45, and 58%, respectively (Table 1). The most common major IOC was MBL (24%) and the most common POC was unplanned return to the operating room (OR) (19%). Other IOC included cord deficit (2.6%), pneumothorax (1.5%), large vessel injury (1.7%), nerve root injury (1.4%), and cardiac arrest (0.2%). Other POC included motor deficit (12.1%), deep infection (7.6%), acute respiratory distress/failure (4.7%), deep venous thrombosis (3.1%), pulmonary embolism (2.8%), arrhythmia (1.2%), reintubation and sepsis (0.7%), cauda equine syndrome, myocardial infarction, visual deficit, stroke (0.5%), and death (0.2%). Patients with one 3CO had significantly less POC (43 vs. 69%, p < 0.01) and overall complications (57 vs. 75%, p < 0.01) than patients with two 3CO (Fig. 1). IOC, MBL, and return to the OR were not significantly different between groups. Patients with ThO had significantly more POC (66 vs. 39%, p < 0.01) and overall complications (76 vs. 53%, p < 0.001) than patients with LSO. Patients with LSO had more MBL (25 vs. 14%, p = 0.04). Patients with ThO had more unplanned return to OR (41 vs. 14%, p < 0.001) (Fig. 2). The incidence of IOC was greater for the low-volume sites than high-volume sites (46 vs. 23%, p < 0.001). Low-volume sites had a higher frequency of patients with MBL than high-volume sites (45 vs. 18%, p < 0.001) (Fig. 3). Patients who experienced MBL had a significantly longer operating time (p < 0.001) and a higher risk of developing other IOC, POC, and overall complications (OR = 2.18, 1.51, 1.63, respectively) than patients who did not experience substantial blood loss.

Conclusions The overall incidence of complications was 58% following 3CO surgery. There was significant variation in incidence of complications depending on the number, location, and experience of performing osteotomies. Risks for developing complications included having two osteotomies, ThO, surgery at a low-volume center, and blood loss more than 4 L. With a better understanding of 3CO complications and risk factors, physicians may be more informed in the decision-making process of sagittal plane deformity correction.