Asymmetrical pedicle subtraction osteotomy in the lumbar spine in combined coronal and sagittal imbalance

Spinopelvic Parameters in the Elderly: Does Inadequate Correction Portend Worse Outcomes?

Introduction

This study aimed to compare the outcomes of corrective fusion for adult spinal deformity (ASD) in older people using two different sagittal correction goals: the conventional formula of "pelvic incidence (PI)-lumbar lordosis (LL) mismatch <10°" and an undercorrection strategy based on the range of 10°≤PI-LL≤20°.

Methods

A total of 102 consecutive patients (11 male and 91 female patients; mean age, 72.0 years) aged above 65 years with scoliosis >20° or LL<20° who had undergone long-segment fusion from the lower thoracic spine to the pelvis for ASD and had been followed-up for a minimum of two years at our institution since March 2013 were included in this retrospective study. After excluding patients with PI-LL≤-10° on postoperative standing radiographs, the remaining patients were divided into two groups: 31 patients with 10°≤PI-LL≤20° (U group) and 63 patients with -10°

Results

The incidence of proximal junctional kyphosis and mechanical failure was not significantly different between the groups (p=0.659 and 1.000, respectively). After excluding patients who underwent reoperation due to mechanical failure, there were no differences in the Oswestry Disability Index (ODI) and each domain of the Visual Analog Scale score, Scoliosis Research Society-22r patient questionnaire (SRS-22r), or the short form 36 health survey questionnaire at the final observation between the U (n=27) and M (n=57) groups. In addition, the non-inferiority and equivalence of the U group to the M group were demonstrated in all domains of the SRS-22r and ODI. Furthermore, the superiority of the U group was demonstrated by the functional domain of SRS-22r.

Conclusions

For the sagittal correction goal in corrective fusion surgery for ASD in the elderly, strict adherence to "PI-LL mismatch <10°" is not necessary and "PI-LL≤20°" may be acceptable.

Collapse

Key Words

• Scoliosis Research Society-Schwab classification
• adult spinal deformity
• elderly patients with spinal deformity
• extensive corrective fusion
• pelvic incidence minus lumbar lordosis mismatch
• sagittal corrective goal
• undercorrection

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Masanari Takami Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shunji Tsutsui Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Keiji Nagata Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Iwasaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Akihito Minamide Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Dokkyo Medical University Nikko Medical Center, Nikko, Japan
Yasutsugu Yukawa Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Nagoya Kyoritsu Hospital, Nagoya, Japan
Motohiro Okada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Department of Orthopaedic Surgery, Sumiya Orthopaedic Hospital, Wakayama, Japan
Ryo Taiji Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shizumasa Murata Department of Orthopaedic Surgery, Shingu Municipal Medical Center, Shingu, Japan
Takuhei Kozaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Hashizume Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Yamada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan

Collapse

The kickstand rod technique for correction of coronal malalignment in patients with adult spinal deformity: a systematic review and pooled analysis of 97 cases

Coronal malalignment (CM) has recently gained focus as a key predictor of functional outcomes in patients with adult spinal deformity (ASD). The kickstand rod technique has been described as a novel technique for CM correction using an accessory rod on the convex side of the deformity. This review aimed to evaluate the surgical technique and outcomes of corrective surgery using this technique. The literature search was conducted on three databases (PubMed, EMBASE, and Scopus). After reviewing the search results, six studies were shortlisted for data extraction and pooled analysis. Weighted means for surgical duration, length of stay, amount of coronal correction, and sagittal parameters were calculated. The studies included in the review were published between 2018 and 2023, with a total sample size of 97 patients. The mean age of the study cohort was 61.1 years, with female preponderance. The mean operative time was 333.6 minutes. The mean correction of CM was 5.1 cm (95% confidence interval [CI], 3.6-6.6), the mean sagittal correction was 5.6 cm (95% CI, 4.1-7.1), and the mean change in lumbar lordosis was 17° (95% CI, 10.4-24.1). Preoperative coronal imbalance and mean correction achieved postoperatively were directly related with age. The reoperation rate was 13.2%. The kickstand rod technique compares favorably with conventional techniques such as asymmetric osteotomies in CM management. This technique provides an additional accessory rod that helps increase construct stiffness. Because of limited data, definitive conclusions cannot be drawn from this review; however, this technique is a valuable tool for a surgeon dealing with ASD.

New Effective Intraoperative Techniques for the Prevention of Coronal Imbalance after Circumferential Minimally Invasive Correction Surgery for Adult Spinal Deformity

This study aimed to devise measures and investigate their effect on coronal imbalance (CI) after circumferential minimally invasive correction surgery (CMIS) with lateral lumbar interbody fusion and percutaneous pedicle screw for adult spinal deformity (ASD). A total of 115 patients with ASD who underwent CMIS from the lower thoracic spine to the ilium were included. Patients were stratified based on the distance between the spinous process of the upper instrumented vertebra and central sacrum vertical line (UIV-CSVL) after the first intraoperative rod application into groups P (UIV-CSVL > 10 mm, n = 50) and G (UIV-CSVL < 10 mm, n = 65). Measures to correct postoperative CI introduced during surgery, preoperative and postoperative UIV-CSVL, and changes in UIV-CSVL after various measures (ΔUIV-CSVL) were investigated in group P. Rod rotation (RR), S2 alar-iliac screw distraction (SD), and kickstand-rod (KR) technique were performed in group P. Group P was further divided into group RR (n = 38), group SD (RR and SD) (n = 7), and group KR (RR and KR) (n = 5); the ΔUIV-CSVLs were 13.9 mm, 20.1 mm, and 24.4 mm in these three groups, respectively. Postoperative C7-CSVL < 10 mm was achieved in all three correction groups. In conclusion, our measures enabled sufficient correction of the UIV-CSVL and are useful for preventing CI after CMIS for ASD.

Trans-intervertebral osteotomy classification of posterior spinal corrective osteotomy procedures via the intervertebral space

•This is a diagnostic study for a classification for posterior spinal osteotomy procedures via the intervertebral space.•Proposed ​a novel classification ​with ​excellent reliability ​and ​validity, differ from the SRS-Schwab osteotomy classification.•Give a novel definition of "trans-intervertebral osteotomy" (TIO) for posterior spinal osteotomy procedures.•Thoroughly discussed about the histories of posterior spinal osteotomy procedures via the intervertebral space.•Systematically introduced the TIO technique with fine original schematics.

Lateral interbody release for fused vertebrae via transpsoas approach in adult spinal deformity surgery: a preliminary report of radiographic and clinical outcomes

BACKGROUND

Lateral interbody release (LIR) via a transpsoas lateral approach is a surgical strategy to address degenerative lumbar scoliosis (DLS) patients with anterior autofusion of vertebral segments. This study aimed to characterize the clinical and radiographic outcomes of this lumbar reconstruction strategy using LIR to achieve anterior column correction.

METHODS

Data for 21 fused vertebrae in 17 consecutive patients who underwent LIR between January 2014 and March 2020 were reviewed. Demographic and intraoperative data were recorded. Radiographic parameters were assessed preoperatively and at final follow-up, including segmental lordotic angle (SLA), segmental coronal angle (SCA), bone union rate, pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt, sacral slope, PI-LL mismatch, sagittal vertical axis, Cobb angle, and deviation of the C7 plumb line from the central sacral vertical line. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), visual analog scale (VAS) scores for low back and leg pain, and the short form 36 health survey questionnaire (SF-36) postoperatively and at final follow-up. Complications were also assessed.

RESULTS

Mean patient age was 70.3 ± 4.8 years and all patients were female. Average follow-up period was 28.4 ± 15.3 months. Average procedural time to perform LIR was 21.3 ± 9.7 min and was not significantly different from traditional lateral interbody fusion at other levels. Blood loss per single segment during LIR was 38.7 ± 53.2 mL. Fusion rate was 100.0% in this cohort. SLA improved significantly from - 7.6 ± 9.2 degrees preoperatively to 7.0 ± 8.8 degrees at final observation and SCA improved significantly from 19.1 ± 7.8 degrees preoperatively to 8.7 ± 5.9 degrees at final observation (P < 0.0001, and < 0.0001, respectively). All spinopelvic and coronal parameters, as well as ODI and VAS, improved significantly. Incidence of peri- and postoperative complications such as iliopsoas muscle weakness and leg numbness in patients who underwent LIR was as much as XLIF. Incidence of postoperative mechanical failure following LIR was also similar to XLIF. Reoperation rate was 11.8%. However, there were no reoperations associated with LIR segments.

CONCLUSIONS

The LIR technique for anterior column realignment of fused vertebrae in the context of severe ASD may be an option of a safe and effective surgical strategy.

Pedicle subtraction osteotomy with patient-specific instruments

Background

Although the utility of patient-specific instruments (PSI) has been well established for complex osteotomies in orthopedic surgery, it is yet to be comparatively analyzed for complex spinal deformity correction, such as pedicle subtraction osteotomy (PSO).

Methods

Six thoracolumbar human cadavers were used to perform nine PSOs using the free-hand (FH) technique and nine with PSI (in total 18 PSOs). Osteotomy planes were planned on the basis of preoperative computed tomography (CT). A closing-wedge angle of 30° was targeted for each PSO. Postoperative CT scans were obtained to measure segmental lordosis correction and the deviation from the planned 30° correction as well as the osseous gap of posterior elements.

Results

The time required to perform a PSO was 18:22 (range 10:22–26:38) min and 14:14 (range 10:13–22:16) min in the PSI and FH groups, respectively (p = 0.489). The PSI group had a significantly higher lordosis gain (29°, range 23–31° vs. 21°, range 13–34°; p = 0.015). The lordosis gain was significantly more accurate with PSI (deviation angle: 1°; range 0–7°) than with the FH technique (9°; range 4–17°; p = 0.003). PSI achieved a significantly smaller residual osseous gap of the posterior elements (5 mm; range 0–9 mm) than the FH group (11 mm; range 3–27 mm; p = 0.043).

With PSI, an angular difference of 3° (range 1–12°), a translational offset of 1 (range 0–6) mm at the level of the lamina, and a vertebral body entry point deviation of 1 (range 0–4) mm was achieved in the osteotomies.

Conclusions

PSI-guided PSO can be a more feasible and accurate approach in achieving a planned lordosis angle than the traditional FH technique in a cadaver model. This approach further reduced osseous gaps, potentially promoting higher fusion rates in vivo.

Coronal Correction Using Kickstand Rods for Adult Thoracolumbar/Lumbar Scoliosis: Case Series With Analysis of Early Outcomes and Complications

BACKGROUND

The "kickstand rod technique" has been recently described for achieving and maintaining coronal correction in adult spinal deformity (ASD). Kickstand rods span scoliotic lumbar spine from the thoracolumbar junction proximally to a "kickstand iliac screw" distally. Using the iliac wing as a base, kickstand distraction produces powerful corrective forces. Limited literature exists for this technique, and its associated outcomes and complications are unknown.

OBJECTIVE

To assess alignment changes, early outcomes, and complications associated with kickstand rod distraction for ASD.

METHODS

Consecutive ASD patients treated with kickstand distraction at our institution were retrospectively analyzed.

RESULTS

The cohort comprised 19 patients (mean age: 67 yr; 79% women; 63% prior fusion) with mean follow-up 21 wk (range: 2-72 wk). All patients had posterior-only approach surgery with tri-iliac fixation (third iliac screw for the kickstand) for mean fusion length 12 levels. Three-column osteotomy and lumbar transforaminal lumbar interbody fusion were performed in 5 (26%) and 15 (79%) patients, respectively. Postoperative alignment improved significantly (coronal balance: 8 to 1 cm [P < .001]; major curve: 37° to 12° [P < .001]; fractional curve: 20° to 10° [P < .001]; sagittal balance: 11 to 4 cm [P < .001]; pelvic incidence to lumbar lordosis mismatch: 38° to 9° [P < .001]). Pain Numerical Rating Scale scores improved significantly (back: 7.2 to 4.2 [P = .001]; leg: 5.9 to 1.7 [P = .001]). No instrumentation complications occurred. Motor weakness persisted in 1 patient. There were 3 reoperations (1-PJK, 1-wound dehiscence, and 1-overcorrection).

CONCLUSION

Among 19 ASD patients treated with kickstand rod distraction, alignment, and back/leg pain improved significantly following surgery. Complication rates were reasonable.

Coronal balance with circumferential minimally invasive spinal deformity surgery for the treatment of degenerative scoliosis: are we leaning in the right direction?

OBJECTIVE

Coronal malalignment (CM) in adult spinal deformity is associated with poor outcomes and remains underappreciated in the literature. Recent attempts at classifying CM indicate that some coronal shifts may be more difficult to treat than others. To date, outcomes for circumferential minimally invasive surgery (cMIS) of the spine in the context of these new CM classifications are unreported.

METHODS

A retrospective evaluation of patients with degenerative scoliosis (Cobb angle > 20°) consecutively treated with cMIS at a single institution was performed. Preoperative and 1-year postoperative standing radiographs were used to make the comparisons. Clinical outcome measures were compared. Patients were subgrouped according to the preoperative distance between their C7 plumb line and central sacral vertical line (C7-CSVL) as either coronally aligned (type A, C7-CSVL < 3 cm); shifted ≥ 3 cm toward the concavity (type B); or shifted ≥ 3 cm toward the convexity (type C) of the main lumbar curve.

RESULTS

Forty-two patients were included (mean age 67.7 years). Twenty-six patients (62%) were classified as type A, 5 patients (12%) as type B, and 11 patients (26%) as type C. An average of 4.9 segments were treated. No type A patients developed postoperative CM. All type B patients had CM correction. Six of the 11 type C patients had CM after surgery. Overall, there was an improvement in the C7-CSVL (from 2.4 to 1.8 cm, p = 0.04). Among subgroups, only type B patients improved (from 4.5 to 0.8 cm, p = 0.002); no difference was seen for type A patients (from 1.2 to 1.4 cm, p = 0.32) or type C patients (from 4.3 to 3.1 cm, p = 0.11). Comparing type C patients with postoperative CM versus those without postoperative CM, patients with CM had worse visual analog scale back scores at 1 year (5 vs 1, p = 0.01). Moreover, they had higher postoperative L4 tilt angles (11° vs 5°, p = 0.01), indicating inadequate correction of the lumbosacral fractional curve.

CONCLUSIONS

cMIS improved coronal alignment, curve magnitudes, and clinical outcomes among patients with degenerative scoliosis. It did not result in CM in type A patients and was successful at improving the C7-CSVL in type B patients. Type C patients remain the most difficult to treat coronally, with worse visual analog scale back pain scores in those with postoperative CM. Regional coronal restoration of the lumbosacral fracture curve should be the focus of correction in cMIS for these patients.

Do Adult Spinal Deformity Patients Undergoing Surgery Continue to Improve From 1-Year to 2-Years Postoperative?

OBJECTIVE

Evaluate clinical improvement as measured by patient-reported outcomes (PROs) during the 1 to 2-year interval.

STUDY DESIGN

Retrospective Cohort.

METHODS

A single-institution registry of ASD patients undergoing surgery was queried for patients with ≥6 level fusions. Demographics and radiographic variables were collected. PROs collected were the ODI and SRS-22r scores at: preoperative, 1-year and 2-years. Outcome measures of clinical improvement during the 1-2 year time interval were: 1) group medians, 2) percent minimum clinically important difference (MCID), and 3) percent minimal symptom scale (MSS)(ODI < 20 or SRS-pain + function >8). Wilcoxon rank-sum tests, chi-squared tests, Kruskal-Wallis tests, and logistic regression were performed.

RESULTS

157 patients undergoing ASD surgery with minimum of 1-year follow-up were included. Mean age was 53.2 and mean instrumented levels was 13.1. Preoperative alignment was: Neutral Alignment (NA) 49%, Coronal Malalignment (CM) 17%, Sagittal Malalignment (SM 17%), and Combined Coronal/Sagittal Malalignment (CCSM) 18%. Preoperative to 1-year, and preoperative to 2-years, all ODI/SRS-22r significantly improved (P < .001). In all patients, the only significant improvement in PROs between 1-and 2-year postoperative were those reaching ODI MCID (69% 1-year vs. 84% 2-years; P < .001). Subgroup analysis: ≥55 years had an improved median ODI (18 vs. 8; P = .047) and an improved percent achieving ODI MCID (73% vs. 84%, P = .048). CCSM patients experienced significant improvement in SRS-appearance score (75% vs. 100%; P = .050), along with those with severe preoperative SM >7.5 cm (73% vs. 100%; P = .032).

CONCLUSIONS

Most ASD patients experience the majority of PRO improvement by 1-year postoperative. However, subsets of patients that may continue to improve up to 2-years postoperative include patients ≥55 years, combined coronal/sagittal malalignment, and those with severe sagittal malalignment ≥7.5 cm.

Asymmetrical pedicle subtraction osteotomy for correction of concurrent sagittal-coronal imbalance in adult spinal deformity: a comparative analysis

OBJECTIVE

Rigid multiplanar thoracolumbar adult spinal deformity (ASD) cases are challenging and many require a 3-column osteotomy (3CO), specifically asymmetrical pedicle subtraction osteotomy (APSO). The outcomes and additional risks of performing APSO for the correction of concurrent sagittal-coronal deformity have yet to be adequately studied.

METHODS

The authors performed a retrospective review of all ASD patients who underwent 3CO during the period from 2006 to 2019. All cases involved either isolated sagittal deformity (patients underwent standard PSO) or concurrent sagittal-coronal deformity (coronal vertical axis [CVA] ≥ 4.0 cm; patients underwent APSO). Perioperative and 2-year follow-up outcomes were compared between patients with isolated sagittal imbalance who underwent PSO and those with concurrent sagittal-coronal imbalance who underwent APSO.

RESULTS

A total of 390 patients were included: 338 who underwent PSO and 52 who underwent APSO. The mean patient age was 64.6 years, and 65.1% of patients were female. APSO patients required significantly more fusions with upper instrumented vertebrae (UIV) in the upper thoracic spine (63.5% vs 43.3%, p = 0.007). Radiographically, APSO patients had greater deformity with more severe preoperative sagittal and coronal imbalance: sagittal vertical axis (SVA) 13.0 versus 10.7 cm (p = 0.042) and CVA 6.1 versus 1.2 cm (p < 0.001). In APSO cases, significant correction and normalization were achieved (SVA 13.0-3.1 cm, CVA 6.1-2.0 cm, lumbar lordosis [LL] 26.3°-49.4°, pelvic tilt [PT] 38.0°-20.4°, and scoliosis 25.0°-10.4°, p < 0.001). The overall perioperative complication rate was 34.9%. There were no significant differences between PSO and APSO patients in rates of complications (overall 33.7% vs 42.3%, p = 0.227; neurological 5.9% vs 3.9%, p = 0.547; medical 20.7% vs 25.0%, p = 0.482; and surgical 6.5% vs 11.5%, p = 0.191, respectively). However, the APSO group required significantly longer stays in the ICU (3.1 vs 2.3 days, p = 0.047) and hospital (10.8 vs 8.3 days, p = 0.002). At the 2-year follow-up, there were no significant differences in mechanical complications, including proximal junctional kyphosis (p = 0.352), pseudarthrosis (p = 0.980), rod fracture (p = 0.852), and reoperation (p = 0.600).

CONCLUSIONS

ASD patients with significant coronal imbalance often have severe concurrent sagittal deformity. APSO is a powerful and effective technique to achieve multiplanar correction without higher risk of morbidity and complications compared with PSO for sagittal imbalance. However, APSO is associated with slightly longer ICU and hospital stays.

Predictors and Clinical Importance of Postoperative Coronal Malalignment After Surgery to Correct Adult Spinal Deformity

STUDY DESIGN

A retrospective observational study of a cohort of consecutive patients.

OBJECTIVE

The objective of this study was to determine the correlations between clinical outcomes of spinal surgery to correct adult spinal deformity (ASD) including mechanical complications and coronal malalignment and clarify the risk factors for postoperative coronal malalignment.

SUMMARY OF BACKGROUND DATA

Despite the coronal malalignment seen regularly in adult patients who have undergone spinal surgery to correct spinal deformity, the associations between coronal malalignment, and clinical outcomes including mechanical complications after the surgery have remained unclear until now. To understand the associations between coronal malalignment and outcomes of surgery to correct ASD, and risk factors for postoperative coronal malalignment has substantial clinical importance.

MATERIALS AND METHODS

We included data from 121 consecutive patients who had undergone spinal surgery to correct ASD and were followed up for a minimum of 2 years. Iliac screws were used for pelvic fixation in all cases. The coronal balance was defined as the horizontal distance between the midpoint of C7 and the center of the sacrum on the coronal plane, and coronal malalignment was defined as when the absolute coronal balance was >20 mm. Preoperative radiographic parameters, surgical features, and clinical outcomes including mechanical complications were compared between groups of patients with coronal balance and those with malalignment. Univariate and multivariate regression analysis were used to clarify risk factors for postoperative coronal malalignment.

RESULTS

Postoperative coronal malalignment had no significant association with the clinical outcome as evaluated by a Roland-Morris Disability Questionnaire and Oswestry Disability Index but had a significant association with the frequency of rod fracture. A large preoperative coronal imbalance (malalignment), L5 coronal tilt angle, and use of lateral lumbar interbody fusion were found as risk factors for postoperative coronal malalignment.

CONCLUSION

Postoperative coronal malalignment had no significant association with the clinical outcome as evaluated by the Oswestry Disability Index and Roland-Morris Disability Questionnaire but was significantly associated with the frequency of rod fracture.

LEVEL OF EVIDENCE

Level III.

Validation Study of Rajasekaran's Kyphosis Classification System: Do We Clearly Understand Single- and Two-Column Deficiencies?

Study Design

Multicenter validation study.

Purpose

To evaluate the inter-rater reliability of Rajasekaran’s kyphosis classification through a multicenter validation study.

Overview of Literature

The classification of kyphosis, developed by Rajasekaran, incorporates factors related to curve characteristics, including column deficiency, disc mobility, curve magnitude, and osteotomy requirements. Although the classification offers significant benefits in determining prognosis and management decisions, it has not been subjected to multicenter validation.

Methods

A total of 30 sets of images, including plain radiographs, computed tomography scans, and magnetic resonance imaging scans, were randomly selected from our hospital patient database. All patients had undergone deformity correction surgery for kyphosis. Twelve spine surgeons from the Asia-Pacific region (six different countries) independently evaluated and classified the deformity types and proposed their surgical recommendations. This information was then compared with standard deformity classification and surgical recommendations.

Results

The kappa coefficients for the classification were as follows: 0.88 for type 1A, 0.78 for type 1B, 0.50 for type 2B, 0.40 for type 3A, 0.63 for type 3B, and 0.86 for type 3C deformities. The overall kappa coefficient for the classification was 0.68. Regarding the repeatability of osteotomy recommendations, kappa values were the highest for Ponte’s (Schwab type 2) osteotomy (kappa 0.8). Kappa values for other osteotomy recommendations were 0.52 for pedicle subtraction/disc-bone osteotomy (Schwab type 3/4), 0.42 for vertebral column resection (VCR, type 5), and 0.30 for multilevel VCRs (type 6).

Conclusions

Excellent accuracy was found for types 1A, 1B, and 3C deformities (ends of spectrum). There was more variation among surgeons in differentiating between one-column (types 2A and 2B) and two-column (types 3A and 3B) deficiencies, as surgeons often failed to recognize the radiological signs of posterior column failure. This failure to identify column deficiencies can potentially alter kyphosis management. There was excellent consensus among surgeons in the recommendation of type 2 osteotomy; however, some variation was observed in their choice for other osteotomies.

Multilevel extended posterior column osteotomy plus unilateral cage strutting for degenerative lumbar kyphoscoliosis

OBJECTIVE

To explore the surgical outcome of patients with degenerative lumbar kyphoscoliosis who underwent multilevel extended posterior column osteotomy (PCO) plus unilateral cage strutting (UCS).

METHODS

From Jan 2012 to Aug 2017, 23 patients with degenerative lumbar kyphoscoliosis who underwent multilevel extended PCO plus UCS technique (study group) and 13 patients who underwent asymmetrical pedicle subtraction osteotomy (PSO) technique (control group) were retrospectively reviewed; the radiological features, including coronal/sagittal deformity, and clinical evaluation including Oswestry Disability Index (ODI), visual analog scale (VAS), and Japanese Orthopedic Association (JOA) scores-lumbar were assessed before surgery and at follow-up.

RESULTS

All patients underwent the operation successfully. There was no difference in fusion level, blood loss, and follow-up duration between the two groups; the operation time and length of hospital stay were shorter in study group than that in control group. All patients achieved significant correction of both scoliotic and kyphotic deformity and maintained the correction at minimum of two year follow-up, without any difference in deformity correction and correction loss between the two groups. All patients got back pain and leg pain alleviation and neurological function improvement at two year follow-up, without any difference between the two groups. The incidence of complications was lower in study group than that in control group.

CONCLUSION

Multilevel extended PCO plus UCS procedure could achieve significant correction of scoliosis and kyphosis in the treatment of degenerative lumbar kyphoscoliosis, presenting less surgery time, lower incidence of complication, and shorter hospital stay when compared with the asymmetric PSO technique.

Asymmetric Pedicle Subtraction Osteotomy for Adult Spinal Deformity with Coronal Imbalance: Complications, Radiographic and Surgical Outcomes

BACKGROUND

Asymmetric pedicle subtraction osteotomy (APSO) can be utilized for adult spinal deformity (ASD) with fixed coronal plane imbalance. There are few reports investigating outcomes following APSO and no series that include multiple revision cases.

OBJECTIVE

To detail our surgical technique and experience with APSO.

METHODS

All thoracolumbar ASD cases with a component of fixed, coronal plane deformity who underwent APSO from 2004 to 2016 at one institution were retrospectively reviewed. Preoperative and latest follow-up radiographic parameters and data on surgical outcomes and complications were obtained.

RESULTS

Fourteen patients underwent APSO with mean follow-up of 37-mo. Ten (71.4%) were revision cases. APSO involved a mean 12-levels (range 7-25) and were associated with 3.0 L blood loss (range 1.2-4.5) and 457-min of operative time (range 283-540). Surgical complications were observed in 64.3%, including durotomy (35.7%), pleural injury (14.3%), persistent neurologic deficit (14.3%), rod fracture (7.1%), and painful iliac bolt requiring removal (7.1%). Medical complications were observed in 14.3%, comprising urosepsis and 2 cases of pneumonia. Two 90-d readmissions (14.3%) and 5 reoperations (4 patients, 28.6%) occurred. Mean thoracolumbar curve and coronal vertical axis improved from 31.5 to 16.4 degrees and 7.8 to 2.9 cm, respectively. PI-LL mismatch, mean sagittal vertical axis, and pelvic tilt improved from 40.0 to 27.9-degrees, 10.7 to 3.5-cm, and 34.4 to 28.3-degrees, respectively.

CONCLUSION

The APSO, in both a revision and non-revision ASD population, provides excellent restoration of coronal balance-in addition to sagittal and pelvic parameters. Employment of APSO must be balanced with the associated surgical complication rate (64.3%).

Useful and innovative methods for the treatment of postoperative coronal malalignment in adult scoliosis: the "kickstand rod" and "tie rod" procedures

STUDY DESIGN

Surgical technique description and case series.

OBJECTIVE

To describe the use of two techniques for the correction of postoperative coronal imbalance after surgical treatment for adult spine deformity (ASD). Sagittal and coronal spinal malalignments are often present in patients with ASD or in patients who have undergone spine surgery. Surgical correction of coronal imbalance is insufficiently investigated, and the literature provides a limited spectrum of surgical options when compared to sagittal imbalance. Nevertheless, this deformity can compromise the surgical outcome and can increase the risk of hardware failure.

METHODS

The kickstand (KR) and tie rod (TR) techniques utilize an accessory rod, linking the previous instrumentation to an independent iliac screw. After a proper release of the lumbar spine with anterior release or posterior osteotomies, the KR technique pushes with distraction on the concave side, whereas the TR technique pulls with compression on the convex side. Four patients (mean age, 64 years; SD 5.7) affected by severe postoperative coronal imbalance were treated. C7-PL ranges from 39 to 76 mm. The mean preoperative ODI was 70/100 (range from 55 to 82). All patients had previous spinopelvic fixation as a consequence of corrective surgery for adult spine deformity. The patients were surgically treated with the addition of supplementary rods connected to the ilium. The rods were used in the concavity or convexity of the deformity functioning as "kickstand" or "tie" or a combination of both.

RESULTS

The mean surgical correction of C7-PL was 35 mm (range from 20 to 52 mm). In particular, the mean correction for kickstand rod technique was 26 mm and for tie rod technique was 43 mm. All of the patients improved their preoperative disability, and mean ODI was 30/100 (range from 10 to 60) at median 19-month follow-up. All postoperative imaging showed implants were in proper position without hardware failure. All of the patients treated demonstrated an immediate postoperative improvement in terms of coronal displacement of the spine. No complications were observed. At 1-year follow-up, all of the patients remained satisfactory in terms of clinical outcomes.

CONCLUSION

The kickstand and tie rod techniques are effective in the treatment of postoperative coronal malalignment. Further studies are needed to confirm these findings.

LEVEL OF EVIDENCE

V: Case report. These slides can be retrieved under Electronic Supplementary Material.

Sequential correction technique to avoid postoperative global coronal decompensation in rigid adult spinal deformity: a technical note and preliminary results

PURPOSE

This study aims to evaluate this new sequential correction technique for preventing postoperative coronal imbalance.

METHODS

Adult Spinal deformity (ASD) patients were stratifies into two types: primary thoracolumbar/lumbar (TL/L) curve with compensatory lumbosacral (LS) curve (Type I) and primary LS curve with compensatory TL/L curve (Type II): for Type I patients: correction of major TL/L curve and one- or two-level segmental rod installed at the convexity of the TL/L curve, L4-S1 TLIF to correct fractional curve and a short rod installed on the contralateral side and installation of long rods; for Type II patients: horizontalize L4 and L5, short rod installation at the convexity of the LS curve, distraction of curve with regional rod and installation of long rods. ASD patients were enrolled with inclusion criteria: with pre-op TL/L Cobb angle more than 30°, with pelvic fixation and with UIV over T10. Radiographic parameters were analyzed.

RESULTS

Twenty-one patients were recruited (14 patients Type I and 7 Type II patients). Both Cobb angle and coronal offset were significantly improved after surgery. In Type I patients, Cobb angle was improved from 50.48° to 26.91° and coronal offset from 2.94 to 0.95 cm; in Type II patients, Cobb angle was improved from 61.42° to 28.48° and coronal offset from 2.82 to 1.38 cm. In the 10 patients with baseline coronal imbalance, 9 were corrected to coronal balance after surgery.

CONCLUSION

The sequential correction technique allows decomposing the complex correction surgery into several steps, and each step focuses only on one task. It can also reduce the difficulty of rod installation due to the separated maneuvers and multi-rod system.

LEVEL OF EVIDENCE

IV These slides can be retrieved under Electronic Supplementary Material.

Coronal Imbalance After Three-Column Osteotomy in Thoracolumbar Congenital Kyphoscoliosis: Incidence and Risk Factors

STUDY DESIGN

Retrospective radiographical clinical study.

OBJECTIVE

To investigate the incidence and risk factors of coronal imbalance (CI) after three-column osteotomy (3-CO) in patients with thoracolumbar congenital kyphoscoliosis (CKS).

SUMMARY OF BACKGROUND DATA

The incidence and risk factors of postoperative CI have been reported in adolescent idiopathic and degenerative lumbar scoliosis. However, limited data exists for patients with CKS after 3-CO.

METHODS

We reviewed a consecutive series of patients with CKS who underwent posterior-only 3-CO. Coronal curve patterns were classified according to absolute C7 translation values into: Type A, C7 translation is less than 30 mm; Type B, C7 translation more than or equal to 30 mm and C7 plumb line (C7PL) shifted to the concave side of the main curve; and Type C, C7 translation more than or equal to 30 mm and C7PL shifted to the convex side. CI was defined as C7 translation on either side more than or equal to 30 mm. According to C7 translation at the latest follow-up, patients was subdivided into an imbalanced group and a balanced group.

RESULTS

One-hundred-thirty patients (mean age, 17.7 ± 5.2 yr) were recruited. The mean follow-up was 41.3 ± 18.5 months. Twenty-six patients (20%) were identified as having CI at the latest follow-up. Compared with the balanced group, the imbalanced group had a larger proportion of preoperative Type C pattern, higher main curve correction, and greater lowest instrumented vertebra (LIV) tilt before and after surgery. Multiple logistic regression showed that risk factors for CI were preoperative type C pattern, preoperative LIV tilt more than or equal to 23.5° and immediate postoperative LIV tilt more than or equal to 12.3°.

CONCLUSION

The incidence of CI in patients with CKS after 3-CO was 20%. A preoperative type C pattern, preoperative LIV tilt more than or equal to 23.5°, and immediate postoperative LIV tilt more than or equal to 12.3° were found to be associated with CI at the latest follow-up.

LEVEL OF EVIDENCE

3.

Classification of coronal imbalance in adult scoliosis and spine deformity: a treatment-oriented guideline

INTRODUCTION

In adult spinal deformity (ASD), sagittal imbalance and sagittal malalignment have been extensively described in the literature during the past decade, whereas coronal imbalance and coronal malalignment (CM) have been given little attention. CM can cause severe impairment in adult scoliosis and ASD patients, as compensatory mechanisms are limited. The aim of this paper is to develop a comprehensive classification of coronal spinopelvic malalignment and to suggest a treatment algorithm for this condition.

METHODS

This is an expert's opinion consensus based on a retrospective review of CM cases where different patterns of CM were identified, in addition to treatment modifiers. After the identification of the subgroups for each category, surgical planning for each subgroup could be specified.

RESULTS

Two main CM patterns were defined: concave CM (type 1) and convex CM (type 2), and the following modifiers were identified as potentially influencing the choice of surgical strategy: stiffness of the main coronal curve, coronal mobility of the lumbosacral junction and degeneration of the lumbosacral junction. A surgical algorithm was proposed to deal with each situation combining the different patterns and their modifiers.

CONCLUSION

Coronal malalignment is a frequent condition, usually associated to sagittal malalignment, but it is often misunderstood. Its classification should help the spine surgeon to better understand the full spinal alignment of ASD patients. In concave CM, the correction should be obtained at the apex of the main curve. In convex CM, the correction should be obtained at the lumbosacral junction. These slides can be retrieved under Electronic Supplementary Material.

Risk Factors for Postoperative Coronal Balance in Adult Spinal Deformity Surgery

STUDY DESIGN

A retrospective case-control study.

OBJECTIVES

To determine factors influencing the ability to achieve coronal balance following spinal deformity surgery.

METHODS

Following institutional ethics approval, the radiographs of 47 patients treated for spinal deformity surgery with long fusions to the pelvis, were retrospectively reviewed. The postoperative measurements included coronal balance, L4 tilt, and L5 tilt, levels fused, apical vertebral translation and maximum Cobb angle. L4 and L5 tilt angles were measured between the superior endplate and the horizontal. Sagittal parameters including thoracic kyphosis, lumbar lordosis, pelvic incidence, and sagittal vertical axis were recorded. Coronal balance was defined as the distance between the central sacral line and the mid body of C7 being ≤40 mm. Surgical factors, including levels fused, use of iliac fixation with and without connectors, use of S2A1 screws, interbody devices, and osteotomies. Statistical tests were performed to determine factors that contribute to postoperative coronal imbalance.

RESULTS

Of the 47 patients reviewed, 32 were balanced after surgery and 14 were imbalanced. Coronal balance was 1.30 cm from center in the balanced group compared to 4.83 cm in the imbalanced group (P < .01). Both L4 and L5 tilt were statistically different between the groups. Gender and the use of transverse connectors differed between the groups but not statistically.

CONCLUSIONS

In adult spinal deformity patients undergoing primary fusions to the pelvis, the ability to level the coronal tilt of L4 and L5 had the greatest impact on the ability to achieve coronal balance in this small series. A larger prospective series can help validate this important finding.

A Classification for Kyphosis Based on Column Deficiency, Curve Magnitude, and Osteotomy Requirement

BACKGROUND

There is a lack of a classification system providing uniformity in description and guiding management decisions for kyphotic spinal deformities. We developed such a classification based on column deficiency, flexibility of disc spaces, curve magnitude, and correlation with the corrective osteotomy required.

METHODS

A classification was developed based on analysis of 180 patients with thoracolumbar kyphosis requiring osteotomy. The deformity was classified as Type I if the anterior and posterior columns were intact (IA indicated mobile disc spaces and IB, ankylosed segments). Type II indicated deficiency of only 1 column (IIA = anterior column and IIB = posterior column). Type III indicated deficiency of both columns (IIIA = kyphosis of ≤60°, IIIB = kyphosis of >60°, and IIIC = buckling collapse). A prospective analysis of 76 patients was performed to determine interobserver variability and the ability of the classification to guide selection of osteotomies of increasing complexity, including the Ponte osteotomy, pedicle subtraction osteotomy, disc bone osteotomy, single vertebrectomy, multiple vertebrectomies, and anterior in situ strut fusion procedure.

RESULTS

The mean age of the 76 patients was 21.2 years, the mean kyphosis was 69.9° (range, 26° to 120°), and the mean follow-up duration was 30 months. Six deformities were classified as IA, 5 as IB, 5 as IIA, 2 as IIB, 13 as IIIA, 35 as IIIB, and 10 as IIIC. Four surgeons classifying the deformities had a high agreement rate (kappa = 0.83), with the highest agreement for Types IA, IB, and IIIB. A correlation between the type of deformity and the osteotomy performed demonstrated that the classification could indicate the type of osteotomy required. All 18 patients with Type-I or II kyphosis were treated with Ponte, pedicle subtraction, or disc bone osteotomy. Forty-three (90%) of the 48 patients with Type IIIA or IIIB underwent vertebrectomy (single in 27 [56%] and multiple in 16 [33%]), and only 5 (10%) underwent disc bone osteotomy. Seven of the 10 patients with Type-IIIC kyphosis were treated with multiple vertebrectomies, with 5 of them needing preoperative halo gravity traction; the other 3 patients underwent an anterior in situ strut fusion procedure.

CONCLUSIONS

The proposed classification based on the morphology of column deficiency, flexibility, and curve magnitude demonstrated a high interobserver agreement and ability to guide selection of the appropriate osteotomy.

CLINICAL RELEVANCE

A novel classification system for kyphosis based on spinal column deficiency, flexibility of disc spaces, and curve magnitude would bring uniformity in management and help guide surgeons in the choice of the appropriate corrective osteotomy.

The effect of case-based discussion of topics with experts on learners' opinions: implications for spinal education and training

PURPOSE

This investigation aimed to examine the extent to which case-based discussion with experts could influence the audience's opinions on the treatment of patients during a continuing medical education event for spine surgeons.

METHODS

We conducted a prospective controlled crossover study of 90 surgeons. During a continuing medical education activity using case-based discussion, quiz questions were used which asked participants (attendants and faculty group) their opinions on the best choices about diagnosis and treatment in a number of cases. No answer was considered correct, but we evaluated the number of participants choosing each specific answer among a number of valid options. Quiz questions were collected with an automated response system at the entry and at the end of each case discussion. Change in participant's opinions was estimated from the change in the preferred answers between the entry and exit quizzes. Chi-square analysis was performed to determine significance.

RESULTS

Sixty-two attendants out of eighty three (75%) and six faculties out of twelve (50%) responded to the survey. After the case discussion, 68.2% (p < 0.04, Chi-square test) of the attendants changed their opinion on the appropriate treatment. The faculty answers, however, showed no significant change in opinions regarding the identification of the appropriate treatment.

CONCLUSIONS

On the basis of our results, case-based discussion driven by experts, as a form of teaching, has a measurable effect in terms of changes in the learners' opinions.

Adult Degenerative Lumbar Scoliosis

Adult degenerative lumbar scoliosis is a 3-dimensional deformity defined as a coronal deviation of greater than 10°. It causes significant pain and disability in the elderly. With the aging of the population, the incidence of adult degenerative lumbar scoliosis will continue to increase. During the past decade, advancements in surgical techniques and instrumentation have changed the management of adult spinal deformity and led to improved long-term outcomes. In this article, the authors provide a comprehensive review of the pathophysiology, diagnosis, and management of adult degenerative lumbar scoliosis. [Orthopedics. 2017; 40(6):e930-e939.].

The effect of case-based discussion of topics with experts on learners' opinions: implications for spinal education and training

PURPOSE

This investigation aimed to examine the extent to which case-based discussion with experts could influence the audience's opinions on the treatment of patients during a continuing medical education event for spine surgeons.

METHODS

We conducted a prospective controlled crossover study of 90 surgeons. During a continuing medical education activity using case-based discussion, quiz questions were used which asked participants (attendants and faculty group) their opinions on the best choices about diagnosis and treatment in a number of cases. No answer was considered correct, but we evaluated the number of participants choosing each specific answer among a number of valid options. Quiz questions were collected with an automated response system at the entry and at the end of each case discussion. Change in participant's opinions was estimated from the change in the preferred answers between the entry and exit quizzes. Chi-square analysis was performed to determine significance.

RESULTS

Sixty-two attendants out of eighty three (75%) and six faculties out of twelve (50%) responded to the survey. After the case discussion, 68.2% (p < 0.04, Chi-square test) of the attendants changed their opinion on the appropriate treatment. The faculty answers, however, showed no significant change in opinions regarding the identification of the appropriate treatment.

CONCLUSIONS

On the basis of our results, case-based discussion driven by experts, as a form of teaching, has a measurable effect in terms of changes in the learners' opinions.

A proposed classification system for guiding surgical strategy in cases of severe spinal deformity based on spinal cord function

PURPOSE

Spinal cord function classification systems are not useful for guiding surgery in patients with severe spinal deformities. The aim of this study is to propose a classification system for determining a surgical strategy that minimizes the risk of neurological dysfunction in patients with severe spinal deformities.

METHODS

The records of 89 patients with severe spinal deformities treated with vertebral column reconstruction from 2008 to 2013 were retrospectively analyzed. Based on neurophysiological monitoring, magnetic resonance imaging, and neurological symptoms patients were categorized into three groups: group A, normal spinal cord, normal evoked potentials and no neurological symptoms; group B, spinal cord abnormalities and/or abnormal evoked potentials but no neurological symptoms; group C, neurological symptoms with or without spinal cord abnormalities/abnormal evoked potentials. Outcomes and complications were compared between the groups.

RESULTS

A total of 89 patients (51 male, 38 female) were included with 47 (52.8 %), 16 (18.0 %), and 26 (29.2 %) patients in groups A, B and C, respectively, and a mean follow-up 34.5 months. There were no differences in age, gender, average preoperative scoliosis, and kyphosis among three groups, but there were differences with respect to the causes of severe spinal deformity and the corrective rate of scoliosis and kyphosis. Changes in intraoperative evoked potentials were different in these three types according to this new classification, and the recovery rates of changes in the three groups were 71.1, 50.0, and 14.1 %, respectively. Postoperative spinal cord injury was positively related to intraoperative changes of evoked potentials.

CONCLUSION

The classification system may be useful for guiding surgical decisions in patients with severe spinal deformities to minimize the risk of neurological complications.

Planning the Surgical Correction of Spinal Deformities: Toward the Identification of the Biomechanical Principles by Means of Numerical Simulation

In decades of technical developments after the first surgical corrections of spinal deformities, the set of devices, techniques, and tools available to the surgeons has widened dramatically. Nevertheless, the rate of complications due to mechanical failure of the fixation or the instrumentation remains rather high. Indeed, basic and clinical research about the principles of deformity correction and the optimal surgical strategies (i.e., the choice of the fusion length, the most appropriate instrumentation, and the degree of tolerable correction) did not progress as much as the implantable devices and the surgical techniques. In this work, a software approach for the biomechanical simulation of the correction of patient-specific spinal deformities aimed to the identification of its biomechanical principles is presented. The method is based on three-dimensional reconstructions of the spinal anatomy obtained from biplanar radiographic images. A user-friendly graphical user interface allows for the planning of the desired deformity correction and to simulate the implantation of pedicle screws. Robust meshing of the instrumented spine is provided by using consolidated computational geometry and meshing libraries. Based on a finite element simulation, the program is able to predict the loads and stresses acting in the instrumentation as well as those in the biological tissues. A simple test case (reduction of a low-grade spondylolisthesis at L3–L4) was simulated as a proof of concept, and showed plausible results. Despite the numerous limitations of this approach which will be addressed in future implementations, the preliminary outcome is promising and encourages a wide effort toward its refinement.