Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery

The Sagittal Balance Does not Influence the 1 Year Clinical Outcome of Patients With Lumbar Spinal Stenosis Without Obvious Instability After Microsurgical Decompression

STUDY DESIGN

A retrospective study with retrospective and prospective inclusion of 100 patients.

OBJECTIVE

To determine whether the sagittal balance (SB) influences the clinical outcome of patients with degenerative lumbar spinal stenosis, who underwent microsurgical decompression.

SUMMARY OF BACKGROUND DATA

The SB has become a critical factor for clinical decision making in the surgical treatment of spinal degenerative diseases. However, a frequently recommended sagittal realignment of elderly, multimorbid patients is accompanied by a significant rate of complications. The influence of SB on the clinical outcome of patients with degenerative spinal stenosis, who undergo decompressive surgery is not well understood. The aim of this study was to explore whether the clinical outcome of these patients is related to the SB and whether patients with spinal stenosis and degenerative sagittal imbalance necessitate restoration of the SB in addition to microsurgical decompression.

METHODS

One hundred patients with lumbar spinal stenosis, who received microsurgical decompression, were retrospectively identified and classified according to the severity of sagittal imbalance: (1) normal balance group, (2) minor loss of balance group, and (3) major loss of balance group. Sagittal parameters were determined from preoperative lateral spinal radiographs. As outcome parameters, we analyzed pre- and postoperative visual analogue scales for leg and back pain, walking distance, Oswestry disability index, Roland and Morris disability questionnaire, Odom's criteria, and the SF-36 score.

RESULTS

All groups significantly benefited from surgery concerning leg pain, back pain, and disability in every day's life. There was no difference in patients with decompensated sagittal imbalance compared to patients with normal SB regarding life quality 6 to 24 months after microsurgical decompression.

CONCLUSIONS

Patients with symptomatic degenerative spinal stenosis and excluded major instability significantly benefit from microsurgical decompression regardless of their sagittal spinal balance. Thus, restoration of the SB for patients with symptomatic degenerative spinal stenosis cannot be recommended in addition to microsurgical decompression.

LEVEL OF EVIDENCE

3.

Flatback Revisited: Reciprocal Loss of Lumbar Lordosis Following Selective Thoracic Fusion in the Setting of Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective review of prospective multicenter adolescent idiopathic scoliosis (AIS) database.

OBJECTIVE

To investigate the relationship between iatrogenic loss of thoracic kyphosis (TK) after selective thoracic posterior spinal instrumentation and fusion (PSIF) for AIS with straightening of lumbar lordosis (LL).

SUMMARY OF BACKGROUND DATA

Segmental PSIF has become the standard of care for surgical treatment of severe AIS. Studies show that adults with flattening of TK and LL can develop pain and dysfunction associated with flatback syndrome. Analysis of post-fusion sagittal alignment is lacking in the AIS population.

METHODS

Query of prospective multicenter database for AIS patients with Lenke 1, 2, or 3 curves who underwent selective thoracic PSIF (lowest instrumented vertebra equal or cephalad to L1) identified 123 patients with a minimum of 2 years' follow-up. Thoracic kyphosis (T5-T12), LL (T12-S1), and global sagittal alignment were measured preoperatively and at 2 years postoperatively. Health-related quality of life measures were examined.

RESULTS

A total of 31% of patients had loss of TK and 42% lost LL. Patients with decreased TK had significantly higher rates of decreased LL (68%) than patients without decreased TK (31%). Multivariate regression confirmed that TK had significant predictive effect on LL (p < .001). Specifically, change in TK of 2° was associated with roughly 3° change in LL. There were no significant associations between changes in TK or LL and health-related quality of life.

CONCLUSIONS

Loss of TK occurs commonly in selective fusion for AIS. This loss of kyphosis is strongly associated with reciprocal loss of LL. Spinal fusion can have unintended effects on sagittal alignment; these effects may have consequences that remain to be fully elucidated.

The influence of preoperative spinal sagittal balance on clinical outcomes after microendoscopic laminotomy in patients with lumbar spinal canal stenosis

OBJECT

More information about the association between preoperative anterior translation of the C-7 plumb line and clinical outcomes after decompression surgery in patients with lumbar spinal canal stenosis (LSS) would help resolve problems for patients with sagittal imbalance. The authors evaluated whether preoperative sagittal alignment of the spine affects low-back pain and clinical outcomes after microendoscopic laminotomy.

METHODS

This study was a retrospective review of prospectively collected surgical data. The study comprised 88 patients with LSS (47 men and 41 women) who ranged in age from 39 to 86 years (mean age 68.7 years). All patients had undergone microendoscopic laminotomy at Osaka City University Graduate School of Medicine from May 2008 through October 2012. The minimum duration of clinical and radiological follow-up was 6 months. All patients were evaluated by Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores for low-back pain, leg pain, and leg numbness before and after surgery. The distance between the C-7 plumb line and the posterior corner of the sacrum (sagittal vertical axis [SVA]) was measured on lateral standing radiographs of the entire spine obtained before surgery. Radiological factors and clinical outcomes were compared between patients with a preoperative SVA ≥ 50 mm (forward-bending trunk [F] group) and patients with a preoperative SVA < 50 mm (control [C] group). A total of 35 patients were allocated to the F group (19 male and 16 female) and 53 to the C group (28 male and 25 female).

RESULTS

The mean SVA was 81.0 mm for patients in the F group and 22.0 mm for those in the C group. At final follow-up evaluation, no significant differences between the groups were found for the JOA score improvement ratio (73.3% vs 77.1%) or the VAS score for leg numbness (23.6 vs 24.0 mm); the VAS score for low-back pain was significantly higher for those in the F group (21.1 mm) than for those in the C group (11.0 mm); and the VAS score for leg pain tended to be higher for those in the F group (18.9 ± 29.1 mm) than for those in the C group (9.4 ± 16.0 mm).

CONCLUSIONS

Preoperative alignment of the spine in the sagittal plane did not affect JOA scores after microendoscopic laminotomy in patients with LSS. However, low-back pain was worse for patients with preoperative anterior translation of the C-7 plumb line than for those without.

Analysis of mechanical failure associated with reoperation in spinal fusion to the sacrum in adult spinal deformity

BACKGROUND

Long fusion to the sacrum has been demonstrated to increase the mechanical failure rate after adult spinal deformity (ASD) surgery, and these mechanical failures are the most common etiology for reoperation. The purpose of this study was to determine the incidence and risk factors for mechanical failure associated with reoperation after spinal fusion to the sacrum in ASD.

METHODS

The study included 76 patients with ASD who underwent spinal fusion surgery including the sacrum at a single institution between 2005 and 2010. The inclusion criteria were a minimum age of 20 years and fusion of ≥ 5 levels. The terminal event was defined as either the first reoperation for mechanical failure or a minimum of 2 years following surgery in patients who did not undergo reoperation.

RESULTS

The cumulative reoperation rate for mechanical failure was 37 % (n = 28). The procedure survival rate was 79 % at 1 year and 72 % at 2 years. Mechanical failures consisted of proximal junctional complications in 16 patients and pseudarthrosis in 12 patients. Proximal junctional kyphosis (PJK) was the most frequent cause (n = 15), and seven patients were diagnosed with fractures at the UIV or one level above the UIV. Multivariate analysis identified the following as independent factors predicting mechanical failure: three or more comorbidities, smoking, and a preoperative sagittal vertical axis of >95 mm. SRS-22r and ODI scores were lower in patients with mechanical failure.

CONCLUSION

Overall, 37 % of the patients who underwent ASD surgery involving the sacrum required reoperation for mechanical failure. The most frequent form of mechanical failure associated with reoperation was surgical PJK. Significant risk factors for mechanical failure included medical comorbidities, smoking, and severe preoperative sagittal imbalance. Critical mechanical failure may have a negative influence on health status.

Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Disorders: Mini-open TLIF and Corrective TLIF

Minimally invasive transforaminal lumbar interbody fusion (TLIF) as a short fusion is widely accepted among the spine surgeons. However in the long fusion for degenerative kyphoscoliosis, corrective spinal fixation by an open method is thought to be frequently selected. Our objective is to study whether the mini-open TLIF and corrective TLIF contribute to the improvement of the spinal segmental and global alignment. We divided the patients who performed lumbar fixation surgery into three groups. Group 1 (G1) consisted of mini-open TLIF procedures without complication. Group 2 (G2) consisted of corrective TLIF without complication. Group 3 (G3) consisted of corrective TLIF with instrumentation-related complication postoperatively. In all groups, the lumbar lordosis (LL) highly correlated with developing surgical complications. LL significantly changed postoperatively in all groups, but was not corrected in the normal range in G3. There were statistically significant differences in preoperative and postoperative LL and mean difference between the pelvic incidence (PI) and LL between G3 and other groups. The most important thing not to cause the instrumentation-related failure is proper correction of the sagittal balance. In the cases with minimal sagittal imbalance with or without coronal imbalance, short fusion by mini-open TLIF or long fusion by corrective TLIF contributes to good clinical results if the lesion is short or easily correctable. However, if the patients have apparent sagittal imbalance with or without coronal imbalance, we should perform proper correction of the sagittal spinal alignment introducing various technologies.

Evaluating Kyphosis and Lordosis in Students by Using a Flexible Ruler and Their Relationship with Severity and Frequency of Thoracic and Lumbar Pain

Study Design

A cross-sectional, descriptive study.

Purpose

This study aimed to investigate the relationship between kyphosis and lordosis measured by using a flexible ruler and musculoskeletal pain in students of Hamadan University of Medical Sciences.

Overview of Literature

The spine supports the body during different activities by maintaining appropriate body alignment and posture. Normal alignment of the spine depends on its structural, muscular, bony, and articular performance.

Methods

Two hundred forty-one students participated in this study. A single examiner evaluated the angles of lumbar lordosis and thoracic kyphosis by using a flexible ruler. To determine the severity and frequency of pain in low-back and inter-scapular regions, a tailor-made questionnaire with visual analog scale was used. Finally, using the Kendall correlation coefficient, the data were statistically analyzed.

Results

The mean value of lumbar lordosis was 34.46°±12.61° in female students and 22.46°±9.9° in male students. The mean value of lumbar lordosis significantly differed between female and male students (p<0.001). However, there was no difference in the level of the thoracic curve (p=0.288). Relationship between kyphosis measured by using a flexible ruler and inter-scapular pain in male and female students was not significant (p=0.946). However, the relationship between lumbar lordosis and low back pain was statistically significant (p=0.006). Also, no significant relationship was observed between abnormal kyphosis and frequency of inter-scapular pain, and between lumbar lordosis and low back pain.

Conclusions

Lumbar lordosis contributes to low back pain. The causes of musculoskeletal pain could be muscle imbalance and muscle and ligament strain.

Restoration of Lumbar Lordosis in Flat Back Deformity: Optimal Degree of Correction

Study Design

A retrospective comparative study.

Purpose

To provide an ideal correction angle of lumbar lordosis (LL) in degenerative flat back deformity.

Overview of Literature

The degree of correction in degenerative flat back in relation to pelvic incidence (PI) remains controversial.

Methods

Forty-nine patients with flat back deformity who underwent corrective surgery were enrolled. Posterior-anterior-posterior sequential operation was performed. Mean age and mean follow-up period was 65.6 years and 24.2 months, respectively. We divided the patients into two groups based on immediate postoperative radiographs-optimal correction (OC) group (PI-9°≤LL<PI+9°) and under-correction (UC) group (LL<PI-9°). We also classified the patients according to the PI of each patient-low PI group (PI<55°) and high PI group (PI≥55°). Radiological and clinical results were analyzed.

Results

Patients in OC group had significantly less correction loss and maintained normal sagittal alignment (sagittal vertical axis<5 cm), as compared to patients in UC group (p<0.05). LL of low PI group significantly maintained within 9° better than high PI group (p<0.05). Oswestry disability index (ODI) significantly decreased at last follow-up, as compared to preoperative state. However, there was no significant difference in last follow-up ODI between the groups.

Conclusions

In flat back deformity, correction of LL to within 9° of PI will result in better sagittal balance. Thus, we recommend sufficient LL to prevent correction loss, especially in patients with high PI.

Cervical compensatory alignment changes following correction of adult thoracic deformity: a multicenter experience in 57 patients with a 2-year follow-up

OBJECT

Alignment changes in the cervical spine that occur following surgical correction for thoracic deformity remain poorly understood. The purpose of this study was to evaluate such changes in a cohort of adults with thoracic deformity treated surgically.

METHODS

The authors conducted a multicenter retrospective analysis of consecutive patients with thoracic deformity. Inclusion criteria for this study were as follows: corrective osteotomy for thoracic deformity, upper-most instrumented vertebra (UIV) between T-1 and T-4, lower-most instrumented vertebra (LIV) at or above L-5 (LIV ≥ L-5) or at the ilium (LIV-ilium), and a minimum radiographic follow-up of 2 years. Sagittal radiographic parameters were assessed preoperatively as well as at 3 months and 2 years postoperatively, including the C-7 sagittal vertical axis (SVA), C2–7 cervical lordosis (CL), C2–7 SVA, T-1 slope (T1S), T1S minus CL (T1S-CL), T2–12 thoracic kyphosis (TK), apical TK, lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), and sacral slope (SS).

RESULTS

Fifty-seven patients with a mean age of 49.1 ± 14.6 years met the study inclusion criteria. The preoperative prevalence of increased CL (CL > 15°) was 48.9%. Both 3-month and 2-year apical TK improved from baseline (p < 0.05, statistically significant). At the 2-year follow-up, only the C2–7 SVA increased significantly from baseline (p = 0.01), whereas LL decreased from baseline (p < 0.01). The prevalence of increased CL was 35.3% at 3 months and 47.8% at 2 years, which did not represent a significant change. Postoperative cervical alignment changes were not significantly different from preoperative values regardless of the LIV (LIV ≥ L-5 or LIV-ilium, p > 0.05 for both). In a subset of patients with a maximum TK ≥ 60° (35 patients) and 3-column osteotomy (38 patients), no significant postoperative cervical changes were seen.

CONCLUSION

Increased CL is common in adult spinal deformity patients with thoracic deformities and, unlike after lumbar corrective surgery, does not appear to normalize after thoracic corrective surgery. Cervical sagittal malalignment (C2–7 SVA) also increases postoperatively. Surgeons should be aware that spontaneous cervical alignment normalization might not occur following thoracic deformity correction.

Accuracies in Measuring Spinopelvic Parameters in Full-Spine Lateral Standing Radiograph

STUDY DESIGN

Prospective comparative study of measuring pelvic incidence (PI) among standing radiographs of whole spine and pelvis and computed tomographic (CT) scans in a cohort of patients.

OBJECTIVE

To analyze accuracies in measuring PI and other spinopelvic parameters.

SUMMARY OF BACKGROUND DATA

Previous reports indicated relatively low agreement in measuring PI even among experienced spinal surgeons; intra- and inter-rater reliability in manually measuring PI were 0.69 (0.62-0.74) and 0.41 (0.36-0.45), respectively; the mean interclass correlation coefficient value of manually measuring PI was 0.881. No study compared PI on standing radiographs with that measured on CT scans.

METHODS

A total of 120 consecutive patients with spinal disease (38 patients had history of hip arthroplasty) who admitted to our hospital from April 2012 for 6 months were enrolled. Subjects had obtained full-spine lateral standing radiograph, standing radiograph of pelvis, and CT scans. Pelvic incidence on full-spine lateral standing radiograph and that on pelvis lateral standing radiograph were measured manually by 2 experienced spinal surgeons. Intra- and interobserver reliability of the measurements were analyzed by using interclass correlation coefficient. On CT scans, PI was measured using 3-dimensional CT scan software (CT-PI). PI among 3 different imaging modalities was evaluated using correlation coefficients.

RESULTS

In whole-spine radiographs, the intra- and interobserver agreement rates with measurements in PI (0.84 and 0.79, respectively) and sacral slope (0.87 and 0.83, respectively) were lower than those in pelvic tilt (0.98 and 0.96, respectively) and PI-lumbar lordosis (0.97 and 0.97, respectively). The correlation coefficient between P-PI and CT-PI was higher (0.95) than that between FS-PI and CT-PI (0.81) and between FS-PI and P-PI (0.85).

CONCLUSION

The reliability of measuring PI is comparatively lower than that of other spinopelvic parameters, and the variability of PI measurement is mainly due to difficulty of precisely identifying sacral endplate.

LEVEL OF EVIDENCE

2.

Comprehensive study of back and leg pain improvements after adult spinal deformity surgery: analysis of 421 patients with 2-year follow-up and of the impact of the surgery on treatment satisfaction

OBJECT

Back and leg pain are the primary outcomes of adult spinal deformity (ASD) and predict patients' seeking of surgical management. The authors sought to characterize changes in back and leg pain after operative or nonoperative management of ASD. Outcomes were assessed according to pain severity, type of surgical procedure, Scoliosis Research Society (SRS)–Schwab spine deformity class, and patient satisfaction.

METHODS

This study retrospectively reviewed data in a prospective multicenter database of ASD patients. Inclusion criteria were the following: age > 18 years and presence of spinal deformity as defined by a scoliosis Cobb angle ≥ 20°, sagittal vertical axis length ≥ 5 cm, pelvic tilt angle ≥ 25°, or thoracic kyphosis angle ≥ 60°. Patients were grouped into nonoperated and operated subcohorts and by the type of surgical procedure, spine SRS-Schwab deformity class, preoperative pain severity, and patient satisfaction. Numerical rating scale (NRS) scores of back and leg pain, Oswestry Disability Index (ODI) scores, physical component summary (PCS) scores of the 36-Item Short Form Health Survey, minimum clinically important differences (MCIDs), and substantial clinical benefits (SCBs) were assessed.

RESULTS

Patients in whom ASD had been operatively managed were 6 times more likely to have an improvement in back pain and 3 times more likely to have an improvement in leg pain than patients in whom ASD had been nonoperatively managed. Patients whose ASD had been managed nonoperatively were more likely to have their back or leg pain remain the same or worsen. The incidence of postoperative leg pain was 37.0% at 6 weeks postoperatively and 33.3% at the 2-year follow-up (FU). At the 2-year FU, among patients with any preoperative back or leg pain, 24.3% and 37.8% were free of back and leg pain, respectively, and among patients with severe (NRS scores of 7–10) preoperative back or leg pain, 21.0% and 32.8% were free of back and leg pain, respectively. Decompression resulted in more patients having an improvement in leg pain and their pain scores reaching MCID. Although osteotomies improved back pain, they were associated with a higher incidence of leg pain. Patients whose spine had an SRS-Schwab coronal curve Type N deformity (sagittal malalignment only) were least likely to report improvements in back pain. Patients with a Type L deformity were most likely to report improved back or leg pain and to have reductions in pain severity scores reaching MCID and SCB. Patients with a Type D deformity were least likely to report improved leg pain and were more likely to experience a worsening of leg pain. Preoperative pain severity affected pain improvement over 2 years because patients who had higher preoperative pain severity experienced larger improvements, and their changes in pain severity were more likely to reach MCID/SCB than for those reporting lower preoperative pain. Reductions in back pain contributed to improvements in ODI and PCS scores and to patient satisfaction more than reductions in leg pain did.

CONCLUSIONS

The authors' results provide a valuable reference for counseling patients preoperatively about what improvements or worsening in back or leg pain they may experience after surgical intervention for ASD.

Sagittal Spinopelvic Parameters in Scheuermann's Kyphosis: A Preliminary Study

STUDY DESIGN

Retrospective, controlled, clinical study.

OBJECTIVES

To define the average values for sagittal spinopelvic parameters including pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) in Scheuermann's kyphosis (SK); evaluate the differences in spinopelvic parameters among patients with SK and unaffected normal controls; and evaluate the correlation of various sagittal spinopelvic parameters to each other in SK and normal controls.

METHODS

Prospectively collected radiographic data from a study on SK were compared with those from previously published series of unaffected patients. Measures were made according to standard, defined measurement methods. Parameters measured included PT, PI, SS, thoracic kyphosis, lumbar lordosis, and radiographic sagittal alignment. Values were compared using independent-samples t test. Pearson correlation coefficient was used to analyze relationships between variables.

RESULTS

A total of 47 patients with SK and 50 control patients, mean age 16.1 and 13.5 years, respectively, were included. In SK, average PI was 42°, average PT was 7°, and average SS was 35°. These values were not different from those of normal controls (PI, 46° [p = .084]; PT, 8° [p = .476]; SS, 37° [p = .162]). Pelvic incidence directly correlated with lordosis in both groups (p < .005). T5-12 kyphosis correlated with lordosis in normal controls (p ≤ .05) but not in the SK group. Kyphosis in SK as quantified by greatest measurable Cobb angle did not correlate with PI or lordosis.

CONCLUSIONS

Sagittal pelvic alignment in patients with SK is not different from that in normal subjects. Furthermore, in SK thoracic kyphosis did not correlate with any distal region of the spine (lumbar or pelvic). Further understanding of the relationship between sagittal spinopelvic alignment in various conditions causing spinal deformity will lead to better treatment of these conditions.

Recruitment of compensatory mechanisms in sagittal spinal malalignment is age and regional deformity dependent: a full-standing axis analysis of key radiographical parameters

STUDY DESIGN

Retrospective review, full-body radiographical analysis of adult patients with sagittal spinal malalignment (SSM).

OBJECTIVE

To investigate the compensatory mechanisms involved in the sagittal plane of the body after progressive spinal sagittal malalignment and to study the impact of age on compensatory mechanism recruitment.

SUMMARY OF BACKGROUND DATA

Patients with SSM recruit compensatory mechanisms to maintain erect posture and horizontal gaze. Mechanisms such as pelvic retroversion, knee flexion, and pelvic shift have been proposed, but how they contribute and how age affects their recruitment are poorly understood.

METHODS

Retrospective review of adult patients with SSM who underwent full-standing axis stereoradiography (EOS imaging). Radiographical measurements were performed with Surgimap. Patients were categorized on the basis of the mismatch between pelvic incidence (PI) and lumbar lordosis (PI-LL). Compensatory mechanisms were normalized to each patient's PI-LL and compared by mismatch groups. In addition, patients were subcategorized into 2 age groups (≥65 and <65 yr) and compared within the same groups of mismatch.

RESULTS

A total of 161 patients with a mean age of 62.93 ± 12.8 years. Mean sagittal vertical axis = 62.3 ± 61.5 mm; pelvic tilt (PT) = 29.2° ± 8.4°; and PI-LL = 21.0° ± 14.9°. Mismatch groups were as follows: group 1: PI-LL 0°-10°; group 2: 10°-20°; group 3: 20°-30°; and group 4: >30°. There were significant differences between all groups with regard to thoracic kyphosis (TK), PT, knee flexion angle, and pelvic shift by analysis of variance (P < 0.001). As PI-LL increased, TK and PT contribution to the compensation cascade decreased and knee flexion angle and pelvic shift contribution increased. Patients with PI-LL of more than 30° who were older had significantly less PT and more TK than patients with similar PI-LL who were younger.

CONCLUSION

Spinopelvic mismatch is an important driver in SSM. Pelvic retroversion and flattening of TK (reduction) become exhausted with increasing mismatch, at which point there seems to be a steady transfer of compensation toward significant participation of the lower limbs. Further analysis suggests differential recruitment of these compensatory mechanisms based upon age.

LEVEL OF EVIDENCE

3.

Complications and neurological deficits following minimally invasive anterior column release for adult spinal deformity: a retrospective study

BACKGROUND

Minimally invasive techniques have become increasing popular and are expanding into deformity surgery. The lateral retroperitoneal transpsoas anterior column release (ACR) is a newer minimally invasive alternative to posterior osteotomy techniques for correcting and promoting global spinal alignment. This procedure attempts to avoid the potential complications associated with conventional osteotomies, but has its own subset of unique complications to be discussed in depth.

METHODS

A retrospective review was performed in all patients who underwent the minimally invasive (MIS) ACR procedure from 2010 to present at our institution. All perioperative and postoperative complications were recorded by an independent reviewer. Demographics, spinopelvic parameters, and operative data were collected. The primary etiologic diagnosis was adult spinal deformity. Spinopelvic parameters were measured based on standing 36-inch scoliosis films.

RESULTS

Thirty-one patients underwent a total of 47 MIS-ACRs. The mean age of the cohort was 62. Mean follow up was 12 months (range 3-38 months). The average change from in lumbar lordosis (LL) was 17.6°, in pelvic tilt was 4.3°, coronal Cobb was 13.9 and in SVA was 3.8 cm. Of the 47 MIS-ACR procedures, there were 9 (9/47, 19 %) major complications related to the ACR. Iliopsoas weakness was seen in eight patients and retrograde ejaculation in one patient. Only one patient remained with mild motor deficit at the most recent follow-up. No revision surgeries were required for the anterolateral approach. There was no vascular, visceral, or infectious complications associated with the MIS-ACR.

CONCLUSION

The MIS-ACR is one of the most technically demanding procedures performed from the lateral transpsoas approach. This procedure has the advantage of maintaining and improving spinal global alignment while minimizing blood loss and excessive tissue dissection. It comes with its own unique set of potentially catastrophic complications and should only be performed by surgeons proficient in both deformity correction and the lateral approach.

Less invasive corrective surgery using oblique lateral interbody fusion (OLIF) including L5-S1 fusion for severe lumbar kyphoscoliosis due to L4 compression fracture in a patient with Parkinson's disease: a case report

Background

Corrective surgery for kyphoscoliosis patients tend to be highly invasive due to osteotomy. The present case introduce less invasive corrective surgery using anterior oblique lateral interbody fusion (OLIF) technique.

Case presentation

An 80-year-old Japanese man with a history of Parkinson’s disease presented to our hospital because of severe kyphoscoliosis and gait disturbance. Considering the postsurgical complications due to osteotomy, we performed an anterior-posterior combined corrective fusion surgery: OLIF of Lumbar (L) 2-3, L3-4, and L4-5 (Medtronic Sofamor Danek, Memphis, TN, USA) followed by L5-Sacral (S) 1 anterior lumbar fusion via the OLIF approach using an anterior intervertebral cage, and posterior L3-4 and L4-5 facetectomy and posterior fusion using percutaneous pedicle screws from Thoracic (T) 10 to S1 with a T-9 hook system. The surgery was performed in a less invasive manner with no osteotomy, and it improved the sagittal alignments with moderate restoration, which improved the patient’s posture and gait disturbance. The patient showed transient muscle weakness of proximal lower extremity contralateral side to the surgical site, which fully recovered by physical rehabilitation 3 months after the surgery.

Conclusion

The surgical corrective procedure using the minimally invasive OLIF method including L5-S1 fusion showed a great advantage in treating degenerative kyphoscoliosis in a Parkinson’s disease patient in its less-invasive approac.

Comparison of two minimally invasive surgery strategies to treat adult spinal deformity

OBJECT

Minimally invasive surgery (MIS) techniques are becoming a more common means of treating adult spinal deformity (ASD). The aim of this study was to compare the hybrid (HYB) surgical approach, involving minimally invasive lateral interbody fusion with open posterior instrumented fusion, to the circumferential MIS (cMIS) approach to treat ASD.

METHODS

The authors performed a retrospective, multicenter study utilizing data collected in 105 patients with ASD who were treated via MIS techniques. Criteria for inclusion were age older than 45 years, coronal Cobb angle greater than 20°, and a minimum of 1 year of follow-up. Patients were stratified into 2 groups: HYB (n = 62) and cMIS (n = 43).

RESULTS

The mean age was 60.7 years in the HYB group and 61.0 years in the cMIS group (p = 0.910). A mean of 3.6 interbody fusions were performed in the HYB group compared with a mean of 4.0 interbody fusions in the cMIS group (p = 0.086). Posterior fusion involved a mean of 6.9 levels in the HYB group and a mean of 5.1 levels in the cMIS group (p = 0.003). The mean follow-up was 31.3 months for the HYB group and 38.3 months for the cMIS group. The mean Oswestry Disability Index (ODI) score improved by 30.6 and 25.7, and the mean visual analog scale (VAS) scores for back/leg pain improved by 2.4/2.5 and 3.8/4.2 for the HYB and cMIS groups, respectively. There was no significant difference between groups with regard to ODI or VAS scores. For the HYB group, the lumbar coronal Cobb angle decreased by 13.5°, lumbar lordosis (LL) increased by 8.2°, sagittal vertical axis (SVA) decreased by 2.2 mm, and LL–pelvic incidence (LL-PI) mismatch decreased by 8.6°. For the cMIS group, the lumbar coronal Cobb angle decreased by 10.3°, LL improved by 3.0°, SVA increased by 2.1 mm, and LL-PI decreased by 2.2°. There were no significant differences in these radiographic parameters between groups. The complication rate, however, was higher in the HYB group (55%) than in the cMIS group (33%) (p = 0.024).

CONCLUSIONS

Both HYB and cMIS approaches resulted in clinical improvement, as evidenced by decreased ODI and VAS pain scores. While there was no significant difference in degree of radiographic correction between groups, the HYB group had greater absolute improvement in degree of lumbar coronal Cobb angle correction, increased LL, decreased SVA, and decreased LL-PI. The complication rate, however, was higher with the HYB approach than with the cMIS approach.

Retrolisthesis as a compensatory mechanism in degenerative lumbar spine

OBJECTIVE

Posterior vertebral translation as a type of spondylolisthesis, retrolisthesis is observed commonly in patients with degenerative spinal problems. Nevertheless, there is insufficient literature on retrolisthesis compared to anterolisthesis. The purpose of this study is to clarify the clinical features of retrolisthesis, and its developmental mechanism associated with a compensatory role in sagittal imbalance of the lumbar spine.

METHODS

From 2003 to 2012, 230 Korean patients who underwent spinal surgery in our department under the impression of degenerative lumbar spinal disease were enrolled. All participants were divided into four groups : 35 patients with retrolisthesis (group R), 32 patients with simultaneous retrolisthesis and anterolisthesis (group R+A), 76 patients with anterolisthesis (group A), and 87 patients with non-translation (group N). The clinical features and the sagittal parameters related to retrolisthesis were retrospectively analyzed based on the patients' medical records.

RESULTS

There were different clinical features and developmental mechanisms between retrolisthesis and anterolisthesis. The location of retrolisthesis was affected by the presence of simultaneous anterolisthesis, even though it predominantly manifest in L3. The relative lower pelvic incidence, pelvic tilt, and lumbar lordosis compared to anterolisthesis were related to the generation of retrolisthesis, with the opposite observations of patients with anterolisthesis.

CONCLUSION

Retrolisthesis acts as a compensatory mechanism for moving the gravity axis posteriorly for sagittal imbalance in the lumbar spine under low pelvic incidence and insufficient intra-spinal compensation.

Unintended Change of Physiological Lumbar Lordosis and Pelvic Tilt After Posterior Spinal Instrumentation and Fusion for Adolescent Idiopathic Scoliosis: How Much Is Too Much?

STUDY DESIGN

Retrospective review of prospective multicenter adolescent idiopathic scoliosis (AIS) database.

OBJECTIVES

To investigate the effect of decreased lumbar lordosis (LL) on measured pelvic tilt (PT) after posterior spinal instrumentation and fusion for AIS and to test the hypothesis that lumbar spinal fusion resulting in mismatched LL is associated with increased PT.

SUMMARY OF BACKGROUND DATA

Interaction between the spine and pelvis highly influences global sagittal alignment (GSA). In adults, correlation between health-related quality of life measures and LL proportional to a patient-specific pelvic incidence (PI) has been established, although the implications of poor sagittal alignment are less well-defined in AIS. This observation warrants further examination of regional spine contour and its relation to the pelvis in AIS.

METHODS

The authors queried a prospective multicenter database for AIS patients who underwent posterior spinal instrumentation and fusion with lowest instrumented vertebra between L2 and L5 and identified 155 patients with minimum 2 years' follow-up. Lumbar lordosis (T12-S1), LL within fusion, LL below fusion, GSA, PT, and PI were measured preoperatively and at 2 years. Change in PT was compared between patients with matched or mismatched LL based on a common clinical definition (LL = PI + 10) and a research-driven model (LL = 0.56 PI + 33.43).

RESULTS

Thirty-eight percent of patients had decreased LL from before surgery to 2 years after surgery. These patients had significantly higher rates of increased PT (73%) than patients without decreased LL (40%). Multivariate regression demonstrated that change in LL, LL within fusion, and GSA had a significant predictive effect on PT (p < .001). Using either definition of LL, patients with LL less than 2 standard deviations from predicted values were more likely to have increased PT.

CONCLUSIONS

Iatrogenic loss of LL commonly occurs in spine fusion for AIS and is associated with a reciprocal increase in PT. As such, spinal fusion in AIS can have unintended effects on sagittal alignment with currently uninvestigated potential consequences in the future.

Surgical correction in patients with lumbar degenerative kyphosis who had low bone mineral density: an analysis of 40 patients with a minimum follow-up of two years

Study Design

Retrospective study.

Purpose

To investigate influence of bone mineral density (BMD) on the surgical correction of lumbar degenerative kyphosis (LDK).

Overview of Literature

No studies so far have reported the influence of BMD on the surgical correction of LDK.

Methods

Forty LDK patients with more than 2 years follow-up were studied. Pelvic incidence (PI), pelvic tilt, sacral slope, sagittal vertical axis (SVA), lumbar lordosis (LL), and thoracic kyphosis were measured preoperatively, immediate postoperatively and at final follow-up. Adverse outcomes: proximal adjacent fractures, sagittal decompensation, pseudoarthrosis, and cage subsidence were documented.

Results

There were 37 females and 3 males. Average age was 65.1±4.5 years and mean follow-up was 34.2±16.7 months. 42.5% were Takemitsu type 3 curves, 27.5% type 2, 20.0% type 4 and 10.0% type 1. 37.5% had osteopenia, 40.0% osteoporosis and 22.5% had severe osteoporosis. SVA improved from 237.0±96.7 mm preoperatively to 45.3±41.8 mm postoperatively (p=0.000). LL improved from 10.5°±14.7° to -40.6°±10.9° postoperatively (p=0.000). At final follow-up SVA deteriorated to 89.8±72.2 mm and LL to 34.7°±15.8° (p=0.000). The association between late sagittal decompensation, pseudoarthrosis, or proximal adjacent fractures and osteoporosis was insignificant. The difference between immediate postoperative LL and PI (PIDiff) had a significant association with sagittal decompensation and pseudoarthrosis.

Conclusions

Osteoporosis did not influence the degree of correction, late sagittal decompensation, proximal adjacent fractures, and pseudoarthrosis in LDK. PIDiff had a significant association with sagittal decompensation and pseudoarthrosis.

Mid- and long-term clinical outcomes of corrective fusion surgery which did not achieve sufficient pelvic incidence minus lumbar lordosis value for adult spinal deformity

Background

Recent studies have demonstrated sagittal spinal balance was more important than coronal balance in terms of clinical result of surgery for adult spinal deformity. Notably, Schwab reported that one of the target spinopelvic parameters for corrective surgery was that pelvic incidence (PI) minus lumbar lordosis (LL) should be within +/- 10 °. The present study aimed to investigate whether the clinical outcome of corrective fusion surgery was really poor for patients who could not acquire sufficient PI-LL value through the surgery.

Methods

The present study included 13 patients (mean 68.5 yrs old) with adult spinal deformity. Inclusion criteria were corrective fusion surgery more than 4 intervertebral levels, PI-LL ≥10° on the whole spine X-ray immediately after surgery, and follow-up period ≥3 years. All surgeries were performed by posterior approach. Parameters using SRS-Schwab classification, proximal junctional kyphosis (PJK) of ≥15°, implants loosening, and non-union were investigated using the total standing spinal X-ray. Clinical outcomes were evaluated by Japanese Orthopaedic Association scores (JOA score), Oswestry Disability Index, SF-36, Visual Analog Scale for low back pain, and satisfaction for surgery using SRS-22 questionnaire.

Results

All patients showed the PI-LL ≥20° before surgery. Although the LL were acquired mean 23.6° after surgery, significant loss of correction was observed at final follow up. The acquired coronal spinal alignment was maintained within the follow-up period. However, sagittal vertical axis (SVA) was shifted forward significantly, from mean 4.5cm immediately after surgery to 11.1cm at final follow-up. Five patients showed PJK, 10 patients showed implants loosening, 8 patients showed non-union at final follow-up. The JOA score and mental health summary measures of SF-36 were significantly improved at final follow-up. The satisfaction score was mean 3.3 points, including 3 patients with ≥4 points, at final follow-up. The satisfaction score correlated negatively with SVA at final follow-up (ρ=-0.58 p=0.03).

Conclusions

The forward shift of SVA was frequently observed, and SVA at final follow-up related to the patient’s satisfaction of surgery. This study indicated the importance of postoperative PI-LL value, but also noted 23% of patients acquired good SVA and satisfaction nevertheless they had inadequate postoperative LL.

Etiology of lumbar lordosis and its pathophysiology: a review of the evolution of lumbar lordosis, and the mechanics and biology of lumbar degeneration

The goal of this review is to discuss the mechanisms of postural degeneration, particularly the loss of lumbar lordosis commonly observed in the elderly in the context of evolution, mechanical, and biological studies of the human spine and to synthesize recent research findings to clinical management of postural malalignment. Lumbar lordosis is unique to the human spine and is necessary to facilitate our upright posture. However, decreased lumbar lordosis and increased thoracic kyphosis are hallmarks of an aging human spinal column. The unique upright posture and lordotic lumbar curvature of the human spine suggest that an understanding of the evolution of the human spinal column, and the unique anatomical features that support lumbar lordosis may provide insight into spine health and degeneration. Considering evolution of the skeleton in isolation from other scientific studies provides a limited picture for clinicians. The evolution and development of human lumbar lordosis highlight the interdependence of pelvic structure and lumbar lordosis. Studies of fossils of human lineage demonstrate a convergence on the degree of lumbar lordosis and the number of lumbar vertebrae in modern Homo sapiens. Evolution and spine mechanics research show that lumbar lordosis is dictated by pelvic incidence, spinal musculature, vertebral wedging, and disc health. The evolution, mechanics, and biology research all point to the importance of spinal posture and flexibility in supporting optimal health. However, surgical management of postural deformity has focused on restoring posture at the expense of flexibility. It is possible that the need for complex and costly spinal fixation can be eliminated by developing tools for early identification of patients at risk for postural deformities through patient history (genetics, mechanics, and environmental exposure) and tracking postural changes over time.

Cervical spine alignment following lumbar pedicle subtraction osteotomy for sagittal imbalance

PURPOSE

The alignment of the cervical spine is of primary importance to maintain horizontal gaze and contributes to the functional outcome of patients. Cervical spine alignment after correction of major sagittal imbalance has rarely been reported in the literature.

METHODS

Retrospective review of 31 consecutive patients with sagittal plane deformities operated by lumbar pedicle subtraction osteotomy. Pre-operative and 3 months post-operative full-length radiographies were analyzed for spinopelvic and cervical-specific parameters.

RESULTS

There was a significant increase in lumbar lordosis (LL), thoracic kyphosis, and sacral slope. There was also a significant decrease in pelvic tilt, pelvic incidence minus LL, knee flexion and sagittal vertical axis. The cervical analysis revealed that there was no significant difference between pre- and post-operative global cervical lordosis (CL) angle and external auditory meatus (EAM) tilt. There was a significant decrease of C7 slope and distal CL, while a significant increase in occipito-C2 (OC2) angle was observed.

CONCLUSION

LL restoration decreased the need of compensation at the pelvis and thoracic spine. The distal CL and C7 slope decreased because there was no need for compensation at this level after the surgery, but the proximal cervical spine takes a slightly flexed position to maintain horizontal sight. EAM tilt measures the head position toward C7, and is close to 0° even in severe cases. Changes of this parameter after surgery are insignificant, probably due to the balance between upper and lower cervical segments; when one of these segments shifts backward the other shifts forward and the result is a balanced head over C7.

Insufficient restoration of lumbar lordosis and FBI index following pedicle subtraction osteotomy is an indicator of likely mechanical complication

PURPOSE

Pedicle subtraction osteotomies (PSO) enable correction of spinal deformities but remain difficult and are associated with high complication rates. This study aimed to prospectively review different post-operative complications and mechanical problems in patients who underwent PSO as treatment for sagittal imbalance as sequelae of degenerative disc disease or previous spinal fusion.

METHOD

This was a descriptive prospective single center study of 63 patients who underwent sagittal imbalance correction by PSO. Radiographic analysis of pre- and post-operative pelvic and spinal parameters was completed based on EOS images following 3D modeling. Global and sub-group analyses were completed based on the Roussouly classification. A systematic analysis of post-operative complications was conducted during hospital stay and at follow-up visits.

RESULTS

Complications included 15 cases (20.2%) of bilateral leg pain, with transient neurological deficit in 6 cases (9.5%), and 9 cases (12.5%) of early surgical site infections. Intra-operative complications included five tears of the dura mater and two cases of excessive blood loss (>5,000 mL). Two mortalities occurred from major intracerebral bleeds in the early post-operative period. Mechanical complications were principally non-union (9 cases) and junctional kyphosis (3 cases). All 19 post-operative complications (28.1%) were revised at an average of 2 years following surgery. All mechanical complications were found in the patients who had insufficient imbalance correction and this was mainly associated with high PI (>60°) or a moderate PI (45-60º) combined with excess FBI pre-operatively that remained >10° post-operatively.

CONCLUSION

Infection and neurologic complications following PSO are relatively common, and frequently reported in the literature. The principal cause of mechanical complications, such as non-union or junctional kyphosis, was insufficient sagittal correction, characterized by post-operative FBI >10°. The risks of insufficient correction are greater in patients with higher pelvic incidence and those patients who required very high correction.

An analysis of spinopelvic sagittal alignment after lumbar lordosis reconstruction for degenerative spinal diseases: how much balance can be obtained?

STUDY DESIGN

A retrospective and radiological study of degenerative spinal diseases.

OBJECTIVE

To explore the changes in spinopelvic sagittal alignment after lumbar instrumentation and fusion of degenerative spinal diseases.

SUMMARY OF BACKGROUND DATA

Efforts have been paid to clarify the ideal postoperative sagittal profile for degenerative spinal diseases. However, little has been published about the actual changes of sagittal alignment after lumbar lordosis reconstruction.

METHODS

Radiographical analysis of 83 patients with spinal degeneration was performed by measuring sagittal parameters before and after operations. Comparative studies of sagittal parameters between short (1 level) and long (≥ 2 level) instrumentation and fusion were performed. Different variances (Δ) of these sagittal parameters before and after operations were calculated and compared. Correlative study and linear regression were performed to establish the relationship between variances.

RESULTS

No significant changes were shown in the short-fusion group postoperatively. In the long-fusion group, postoperative lumbar lordosis (LL) and sacral slope (SS) were significantly increased; pelvic tilt (PT), sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis, and PT/SS were significantly decreased. Different variances of ΔLL, ΔSS, ΔPT, ΔSVA, Δ(pelvic incidence - LL), and ΔPT/SS were significantly greater in the long-fusion group than the short-fusion group. Close correlations were mainly shown among ΔLL, ΔPT, and ΔSVA. Linear regression equations could be developed (ΔPT = -0.185 × ΔLL - 7.299 and ΔSVA = -0.152ΔLL - 1.145).

CONCLUSION

In degenerative spinal diseases, long instrumentation and fusion (≥ 2 levels) provides more efficient LL reconstruction. PT, SS, and SVA improve corresponding to LL in a linear regression model. Linear regression equations could be developed and used to predict PT and SVA change after long instrumentation and fusion for LL reconstruction.

Proximal junctional kyphosis and failure after spinal deformity surgery: a systematic review of the literature as a background to classification development

STUDY DESIGN

Systematic review of literature.

OBJECTIVE

To perform a comprehensive English language systematic literature review of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF), concentrating on incidence, risk factors, health related quality of life impact, prevention strategy, and classification systems.

SUMMARY OF BACKGROUND DATA

PJK and PJF are well described clinical pathologies and are a frequent cause of revision surgery. The development of a PJK classification that correlates with clinical outcomes and guides treatment decisions and possible prevention strategies would be of significant benefit to patients and surgeons.

METHODS

The phrases "proximal junctional," "proximal junctional kyphosis," and "proximal junctional failure" were used as search terms in PubMed for all years up to 2014 to identify all articles that included at least one of these terms.

RESULTS

Fifty-three articles were identified overall. Eighteen articles assessed for risk factors. Eight studies specifically reviewed prevention strategies. There were no randomized prospective studies. There were 3 published studies that have attempted to classify PJK. The reported incidence of PJK ranged widely, from 5% to 46% in patients undergoing spinal instrumentation and fusion for adult spinal deformity. It is reported that 66% of PJK occurs within 3 months and 80% within 18 months after surgery. The reported revision rates due to PJK range from 13% to 55%. Modifiable and nonmodifiable risk factors for PJK have been characterized.

CONCLUSION

PJK and PJF affect many patients after long segment instrumentation after the correction of adult spinal deformity. The epidemiology and risk factors for the disease are well defined. A PJK and PJF scoring system may help describe the severity of disease and guide the need for revision surgery. The development and prospective validation of a PJK classification system is important considering the prevalence of the problem and its clinical and economic impact.

LEVEL OF EVIDENCE

N/A.

Fixed sagittal plane imbalance

Study Design Literature review. Objective To discuss the evaluation and management of fixed sagittal plane imbalance. Methods A comprehensive literature review was performed on the preoperative evaluation of patients with sagittal plane malalignment, as well as the surgical strategies to address sagittal plane deformity. Results Sagittal plane imbalance is often caused by de novo scoliosis or iatrogenic flat back deformity. Understanding the etiology and magnitude of sagittal malalignment is crucial in realignment planning. Objective parameters have been developed to guide surgeons in determining how much correction is needed to achieve favorable outcomes. Currently, the goals of surgery are to restore a sagittal vertical axis < 5 cm, pelvic tilt < 20 degrees, and lumbar lordosis equal to pelvic incidence ± 9 degrees. Conclusion Sagittal plane malalignment is an increasingly recognized cause of pain and disability. Treatment of sagittal plane imbalance varies according to the etiology, location, and severity of the deformity. Fixed sagittal malalignment often requires complex reconstructive procedures that include osteotomy correction. Reestablishing harmonious spinopelvic alignment is associated with significant improvement in health-related quality-of-life outcome measures and patient satisfaction.

Characteristics of sagittal spino-pelvic alignment in Japanese young adults

Study Design

Radiological analysis of normal patterns of sagittal alignment of the spine.

Purpose

This study aimed to clarify the characteristics of normal sagittal spino-pelvic alignment in Asian people.

Overview of Literature

It is known that there are differences in these parameters based on age, gender, and race. In order to properly plan for surgical correction of the spine for Asian patients, it is necessary to understand the normal spino-pelvic alignment parameters for this population.

Methods

This study analyzed 86 Japanese healthy young adult volunteers (48 men and 38 women; age 35.9±11.1 (mean±standard deviation [SD]). The following parameters were measured on lateral standing radiographs of the entire spine: sagittal vertical axis (SVA), horizontal distance between the C7 plumb line and the posterior superior corner of the superior margin of S1, thoracic kyphotic angle (TK), lumbar lordotic angle (LLA), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI).

Results

The values (mean±SD) of SVA, TK, LLA, SS, PT, and PI were 8.45±25.7 mm, 27.5±9.6°, 43.4±14.6°, 34.6±7.8°, 13.2±8.2°, and 46.7±8.9°, respectively. The Japanese young adults evaluated in this study tended to have a smaller PI, LLA, TK, and SVA than most Caucasian people. Regarding gender differences, SVA was significantly longer and TK was significantly smaller in men; however, there was no statistically significant difference in LLA, SS, PA, and PI.

Conclusions

Japanese young adults apparently have smaller PI and LLA values than Caucasian people. When making decisions for optimal sagittal spinal alignment, racial differences should be considered.

Results of the AANS membership survey of adult spinal deformity knowledge: impact of training, practice experience, and assessment of potential areas for improved education

Object

Adult spinal deformity (ASD) surgery is increasing in the spinal neurosurgeon's practice.

Methods

A survey of neurosurgeon AANS membership assessed the deformity knowledge base and impact of current training, education, and practice experience to identify opportunities for improved education. Eleven questions developed and agreed upon by experienced spinal deformity surgeons tested ASD knowledge and were subgrouped into 5 categories: 1) radiology/spinopelvic alignment, 2) health-related quality of life, 3) surgical indications, 4) operative technique, and 5) clinical evaluation. Chi-square analysis was used to compare differences based on participant demographic characteristics (years of practice, spinal surgery fellowship training, percentage of practice comprising spinal surgery).

Results

Responses were received from 1456 neurosurgeons. Of these respondents, 57% had practiced less than 10 years, 20% had completed a spine fellowship, and 32% devoted more than 75% of their practice to spine. The overall correct answer percentage was 42%. Radiology/spinal pelvic alignment questions had the lowest percentage of correct answers (38%), while clinical evaluation and surgical indications questions had the highest percentage (44%). More than 10 years in practice, completion of a spine fellowship, and more than 75% spine practice were associated with greater overall percentage correct (p < 0.001). More than 10 years in practice was significantly associated with increased percentage of correct answers in 4 of 5 categories. Spine fellowship and more than 75% spine practice were significantly associated with increased percentage correct in all categories. Interestingly, the highest error was seen in risk for postoperative coronal imbalance, with a very low rate of correct responses (15%) and not significantly improved with fellowship (18%, p = 0.08).

Conclusions

The results of this survey suggest that ASD knowledge could be improved in neurosurgery. Knowledge may be augmented with neurosurgical experience, spinal surgery fellowships, and spinal specialization. Neurosurgical education should particularly focus on radiology/spinal pelvic alignment, especially pelvic obliquity and coronal imbalance and operative techniques for ASD.

Bilateral tubular minimally invasive surgery for low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS): analysis of a series focusing on postoperative sagittal balance and review of the literature

PURPOSE

To report our early experience with minimally invasive surgery (MIS) in low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS), and to analyze the impact of surgery on postoperative spino-pelvic and sacro-pelvic parameters.

METHODS

Eight patients (mean age 47.6 years) underwent MIS for LDLLS involving in all but one the L5-S1 level. VAS and ODI were used for clinical assessment. Imaging included pre-operative X-rays, CT and MRI scans. Post-operatively, all patients underwent X-rays and CT-scans. Pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) values as well as lumbar lordosis (LL) have been derived from pre- and post-operative standard X-rays.

RESULTS

Mean follow-up is 30.12 months (range 15-42). No complications related to the surgical procedure were observed. Patients reported a satisfactory clinical outcome, as demonstrated by variation in mean VAS (from 9.1 to 3.6) and ODI (from 70.50 to 28.25 %) scores. Comparison between pre- and post-operative sacro-pelvic parameters documented moderate changes, with reduction of PT and increase of SS in all but one patient. Overall sagittal balance of the spine has been evaluated using the sagittal vertical axis (SVA), obtained from post-operative X-rays. Mean value of SVA demonstrated a good sagittal balance of the spine.

CONCLUSION

This series demonstrates that MIS is feasible and effective for LDLLS, as witnesses by the satisfactory clinical results maintained at medium-term follow-up. We submit that TLIF is a valid option but an adequately sized and positioned interbody cage is a key factor to allow satisfactory restoration of segmental lordosis.

Preoperative Planning for Pedicle Subtraction Osteotomy: Does Pelvic Tilt Matter?

STUDY DESIGN

Multicenter, retrospective radiographic analysis.

OBJECTIVES

To evaluate the impact that preoperative spinopelvic parameters have on postoperative sagittal vertical axis (SVA). The researchers hypothesized that patients with a large preoperative pelvic tilt (PT) would require more extensive lumbar pedicle subtraction osteotomy (LPSO) procedures to reestablish anatomic postoperative SVA than patients with normal preoperative PT.

SUMMARY OF BACKGROUND DATA

Restoration of anatomic sagittal spinal alignment has been demonstrated to improve clinical outcomes. However, the degree to which spinopelvic parameters contribute to sagittal spinal malalignment is poorly understood.

METHODS

Multicenter, retrospective analysis of 183 consecutively enrolled adult spinal deformity patients treated with LPSO procedures for correction of sagittal malalignment. Preoperative and postoperative freestanding full-length sagittal X-rays were analyzed for regional curves, pelvic parameters, and global alignment. Only patients with a preoperative SVA greater than 10 cm and a postoperative SVA less than 5 cm were retained for analysis. Patients were divided into 2 groups according to preoperative PT (low PT, less than 30°; and high PT, ≥30°). Independent t test analysis was used to determine differences in correction required to achieve postoperative SVA less than 5 cm.

RESULTS

A total of 55 patients were identified for analysis. Low PT (n = 30) had lower preoperative PT than high PT (n = 25; 25° vs. 42°, respectively; p < .001). Analysis of the osteotomy performed demonstrated that the high PT group required a larger osteotomy resection (30° vs. 23°; p = .039) and a larger correction of lumbar lordosis (-43° vs. -31°; p = .006) to achieve an acceptable postoperative SVA (less than 5 cm).

CONCLUSIONS

This study demonstrates that patients with high PT in conjunction with sagittal spinal malalignment require larger lumbar osteotomy procedures, including a greater osteotomy resection and larger lumbar lordosis correction, to obtain a satisfactory postoperative SVA. Surgeons performing LPSO procedures must evaluate preoperative spinopelvic parameters, including PT, to avoid undercorrection and residual deformity after complex sagittal realignment procedures.

Change in Sagittal Plane Alignment Following Surgery for Scheuermann's Kyphosis

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To evaluate changes in sagittal plane alignment in patients with Scheuermann's kyphosis after spinal fusion.

SUMMARY OF BACKGROUND DATA

Although surgery is commonly undertaken in patients with severe Scheuermann's kyphosis for deformity correction, there are limited data regarding the response of spinopelvic parameters and sagittal plane alignment of the spine to surgical treatment.

METHODS

Eighteen consecutive surgical Scheuermann's kyphosis patients were retrospectively reviewed (mean preoperative kyphosis, 76°). Full-length spine films were evaluated for maximal sagittal Cobb angle, thoracic kyphosis, cervical and lumbar lordosis, pelvic parameters, and sagittal plane alignment. Findings were compared with reported literature values in normal patients.

RESULTS

After surgery, thoracic kyphosis improved significantly, with mean maximum kyphosis improving from 76° to 56° (p = .001). Preoperative cervical lordosis was increased compared with reported normal adolescent values (-35° vs. -5°) and did not significantly change after surgery. Lumbar lordosis decreased significantly after surgery, from -77° to -57° (p = .023). No change was noted in pelvic tilt, sacral slope, or pelvic incidence. Furthermore, there was little improvement in sagittal plane alignment. Preoperatively, 12 of the 18 patients had deviation in sagittal plane alignment greater than 2 cm (5 positive and 7 negative); postoperatively, 11 patients had persistent sagittal imbalance (6 positive and 5 negative). Five patients were noted to have proximal junctional kyphosis and 3 underwent revision surgery for malpositioned screw (1) and loss of distal fixation (2).

CONCLUSIONS

Surgical management of Scheuermann's kyphosis resulted in normalization of thoracic kyphosis and lumbar lordosis. Compared with reported values in unaffected adolescents, cervical lordosis remained increased and most patients had residual sagittal plane imbalance greater than 2 cm on imaging.

Outcomes and complications following posterior long lumbar fusions exceeding three levels

The outcomes and complications of posterior-only lumbar instrumented long fusions exceeding three segments with selective segmental transforaminal lumbar interbody fusion for the treatment of degenerative lumbar scoliosis, kyphosis, or both combined with spondylolisthesis were analyzed to investigate risk factors associated with surgical instrumentation failure. Fifteen consecutive patients with degenerative lumbar scoliosis, kyphosis, or both combined with spondylolisthesis were studied retrospectively. There were 5 male and 10 female patients, with a mean age of 71.8 years. All the patients were followed for a mean duration of 19.4 months postoperatively. Radiographic evaluation included coronal Cobb angle, lumbar lordosis (LL) angle, pelvic incidence (PI), and pelvic tilt (PT). The clinical outcomes were assessed by means of Japanese Orthopedic Association (JOA) score. Patients were divided into two groups: group 1—7 patients with surgical complications; group 2—8 patients without complications. The preoperative and postoperative coronal Cobb's angle were not significantly different between groups 1 and 2. The LL highly correlated with developing surgical complications. There were statistically significant differences in preoperative and postoperative LL and the mean difference between PI and the LL (PI–LL) between groups 1 and 2. Linear correlation and regression analysis showed that there was no correlation between JOA score and the coronal Cobb angle in degenerative scoliosis patients. However, we found a positive correlation between JOA and LL. Our series of long lumbar fusions had a high complication and instrumentation failure. Creating adequate LL angle in harmony with PI was a key to prevent surgical complications and attain neurological improvement.

Surgical treatment of pathological loss of lumbar lordosis (flatback) in patients with normal sagittal vertical axis achieves similar clinical improvement as surgical treatment of elevated sagittal vertical axis

Object

Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence–lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors' objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM.

Methods

The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form–36 scores, and Scoliosis Research Society–22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed.

Results

A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form–36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated –1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed.

Conclusions

Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

Prevalence and type of cervical deformity among 470 adults with thoracolumbar deformity

STUDY DESIGN

Multicenter, prospective, consecutive case series.

OBJECTIVE

To assess prevalence and type of cervical deformity among adults with thoracolumbar (TL) deformity and to assess for associations between cervical deformities and different types of TL deformities.

SUMMARY OF BACKGROUND DATA

Cervical deformity can present concomitantly with TL deformity and have implications for the management of TL deformity.

METHODS

Multicenter, prospective, consecutive series of adult (age >18 yr) patients with TL deformity. Parameters included pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), C2-C7 sagittal vertical axis (C2-C7SVA), C7-S1SVA, and C2-C7 lordosis. Cervical deformity was defined as cervical lordosis more than 0° (cervical kyphosis [CK]) or C2-C7SVA more than 4 cm (cervical positive sagittal malalignment [CPSM]). Patients were stratified by the Scoliosis Research Society-Schwab classification of adult TL deformity, including curve type (N = sagittal deformity, T = thoracic scoliosis, L = lumbar scoliosis, and D = T + L scoliosis) and modifier grades: PT (0: <20°, +: 20°-30°, ++: >30°), C7-S1SVA (0: <4 cm, +: 4-9.5 cm, ++: >9.5 cm), and PI-LL mismatch (0: <10°, +: 10-20°, ++: >20°).

RESULTS

A total of 470 patients met criteria (mean age = 52 yr). Mean cervical lordosis and C2-C7SVA were -8° and 3.2 cm, respectively. CK and CPSM prevalence were 31% and 29%, respectively, and prevalence of CK and/or CPSM was 53%. CK prevalence differed by curve type (N = 15%, L = 27%, D = 37%, T = 49%; P < 0.001); CPSM prevalence did not differ by curve type (P = 0.19). Higher PT grades had lower CK prevalence (0 = 40%, += 27%, ++= 15%; P < 0.001) but greater CPSM prevalence (0 = 23%, += 28%, ++= 45%; P = 0.001). Similarly, higher SVA grades had lower CK prevalence (0 = 40%, += 23%, ++= 11%; P < 0.001) but greater CPSM prevalence (0 = 24%, += 24%, ++= 48%; P < 0.001). Higher PI-LL grades had lower CK prevalence (0 = 35%, += 31%, ++= 22%; P = 0.034) but no CPSM association (P = 0.46).

CONCLUSION

Cervical deformity is highly prevalent (53%) in adult TL deformity. C7-S1SVA, PT, and PI-LL modifiers are associated with cervical deformity prevalence. These findings suggest that TL deformity evaluation should include assessment for concomitant cervical deformity and that further study is warranted to define their potential clinical impact.

LEVEL OF EVIDENCE

3.

Patients with adult spinal deformity treated operatively report greater baseline pain and disability than patients treated nonoperatively; however, deformities differ between age groups

STUDY DESIGN

Multicenter, prospective analysis of consecutive patients with adult spinal deformity (ASD).

OBJECTIVE

Identify age-related radiographical parameters associated with poor health-related quality of life (HRQOL) and treatment preferences for ASD.

SUMMARY OF BACKGROUND DATA

Patients with ASD report discrepant severities of disability. Understanding age-associated differences for reported disability and treatment preferences may improve ASD evaluation and treatment.

METHODS

Baseline demographic, radiographical, and HRQOL values were evaluated in a multicenter, prospective cohort of consecutive patients with ASD.

INCLUSION CRITERIA

ASD, age more than 18 years, and no prior spine surgery. Patients were grouped into those treated operatively (OP) or nonoperatively (NON) and stratified into 3 age groups: G1, 50 years or less; G2, 50 to 65 years; G3, 65 years or more. HRQOL measures included Scoliosis Research Society-22r questionnaire, Oswestry Disability Index, and Short Form-36 Health Survey.

RESULTS

Four hundred ninety-seven patients (OP = 156, NON = 341) with a mean age of 50.4 years met inclusion criteria. The OP group was older (53.3 vs. 49.0 yr), had larger scoliosis (49.3° vs. 43.3°), larger sagittal vertical axis (SVA, 33.2 vs. 13.7 mm), greater pelvic incidence-lumbar lordosis mismatch (6.6°vs. 3.1°), and worse HRQOL scores than the NON group, respectively (P < 0.05). Age stratification demonstrated worsening of SVA, spinopelvic alignment (SPA), and HRQOL scores with increasing age (P < 0.05). Age/treatment stratification demonstrated that younger OP had greater scoliosis than NON (G1OP = 49.9°vs. G1NON = 42.2°; G2OP = 56°vs. G2NON = 47.2°; P < 0.05) but similar SPA as NON. Older OP had similar scoliosis, but larger SVA than NON (G3OP = 100.6 vs. G3NON = 66.4 mm; P < 0.05). OP in all age groups reported worse HRQOL than NON (P < 0.05).

CONCLUSION

Poor HRQOL uniformly determined operative treatment for ASD. Spinal deformities differed between age groups. Younger OP had larger scoliosis but similar SPA and SVA than NON. Older OP had similar scoliosis but worse SVA than NON. Age-associated differences for poor HRQOL must be considered when evaluating patients with ASD.

LEVEL OF EVIDENCE

2.

Pelvic incidence-lumbar lordosis mismatch predisposes to adjacent segment disease after lumbar spinal fusion

PURPOSE

Several risk factors and causes of adjacent segment disease have been debated; however, no quantitative relationship to spino-pelvic parameters has been established so far. A retrospective case-control study was carried out to investigate spino-pelvic alignment in patients with adjacent segment disease compared to a control group.

METHODS

45 patients (ASDis) were identified that underwent revision surgery for adjacent segment disease after on average 49 months (7-125), 39 patients were selected as control group (CTRL) similar in the distribution of the matching variables, such as age, gender, preoperative degenerative changes, and numbers of segments fused with a mean follow-up of 84 months (61-142) (total n = 84). Several radiographic parameters were measured on pre- and postoperative radiographs, including lumbar lordosis measured (LL), sacral slope, pelvic incidence (PI), and tilt.

RESULTS

Significant differences between ASDis and CTRL groups on preoperative radiographs were seen for PI (60.9 ± 10.0° vs. 51.7 ± 10.4°, p = 0.001) and LL (48.1 ± 12.5° vs. 53.8 ± 10.8°, p = 0.012). Pelvic incidence was put into relation to lumbar lordosis by calculating the difference between pelvic incidence and lumbar lordosis (∆PILL = PI-LL, ASDis 12.5 ± 16.7° vs. CTRL 3.4 ± 12.1°, p = 0.001). A cutoff value of 9.8° was determined by logistic regression and ROC analysis and patients classified into a type A (∆PILL <10°) and a type B (∆PILL ≥10°) alignment according to pelvic incidence-lumbar lordosis mismatch. In type A spino-pelvic alignment, 25.5 % of patients underwent revision surgery for adjacent segment disease, whereas 78.3 % of patients classified as type B alignment had revision surgery. Classification of patients into type A and B alignments yields a sensitivity for predicting adjacent segment disease of 71 %, a specificity of 81 % and an odds ratio of 10.6.

CONCLUSION

In degenerative disease of the lumbar spine a high pelvic incidence with diminished lumbar lordosis seems to predispose to adjacent segment disease. Patients with such pelvic incidence-lumbar lordosis mismatch exhibit a 10-times higher risk for undergoing revision surgery than controls if sagittal malalignment is maintained after lumbar fusion surgery.

T1 pelvic angle (TPA) effectively evaluates sagittal deformity and assesses radiographical surgical outcomes longitudinally

STUDY DESIGN

Retrospective review of a multicenter database of consecutive patients undergoing 3-column osteotomy for treatment of adult spinal deformity (ASD).

OBJECTIVE

To rigorously develop a T1 pelvic angle (TPA) categorization paradigm and use it to assess the surgical management of patients with ASD.

SUMMARY OF BACKGROUND DATA

TPA, the angle between the hips-T1 line and hips-S1 endplate line, is a novel spinopelvic parameter that assesses the combined effect of a loss of lordosis on trunk inclination and pelvic retroversion.

METHODS

A prospective, multicenter database of consecutive patients with ASD was queried to identify the severe deformity threshold and meaningful change values for TPA by correlation with Oswestry Disability Index. A separate multicenter, consecutive, retrospective database of patients with ASD treated with single lumbar 3-column osteotomy was then analyzed at baseline, 3-month, and 1-year follow-up. Subjects were classified into well-aligned or poorly aligned groups at 3 months on the basis of TPA. Patients "deteriorated" if they lost more than 1 meaningful change in TPA between 3 months and 1 year and had TPA more than deformity threshold at 1 year.

RESULTS

The severe deformity threshold for TPA was 20° (Oswestry Disability Index > 40) and the meaningful change was 4.1° (Oswestry Disability Index change = 15). Review of the 3-column osteotomy database identified 179 patients with preoperative severe deformity; 63 were well-aligned (TPA < 15.9°) and 73 were poorly aligned (TPA > 20°) at 3-month follow-up. This newly developed TPA categorization mechanism grouped patients in a manner comparable with the Scoliosis Research Society-Schwab Classification. Subjects who were well-aligned at 3 months had less severe baseline deformity, but received more correction, than poorly aligned subjects. Four well-aligned patients and 13 poorly aligned patients deteriorated between 3 months and 1 year after surgery.

CONCLUSION

TPA accounts for sagittal vertical axis and pelvic tilt and shows great promise as a classification tool. Longitudinal analysis demonstrated undercorrection among patients with more severe preoperative deformity. We propose a surgical target of 10° for TPA.

LEVEL OF EVIDENCE

4.

Surgical treatment of Lenke 1 thoracic adolescent idiopathic scoliosis with maintenance of kyphosis using the simultaneous double-rod rotation technique

STUDY DESIGN

Retrospective analysis of a prospectively collected, consecutive, nonrandomized series of patients.

OBJECTIVE

To assess the surgical outcomes of the simultaneous double-rod rotation technique for treating Lenke 1 thoracic adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

With the increasing popularity of segmental pedicle screw spinal reconstruction for treating AIS, concerns regarding the limited ability to correct hypokyphosis have also increased.

METHODS

A consecutive series of 32 patients with Lenke 1 main thoracic AIS treated with the simultaneous double-rod rotation technique at our institution was included. Outcome measures included patient demographics, radiographical measurements, and Scoliosis Research Society questionnaire scores.

RESULTS

All 32 patients were followed up for a minimum of 2 years (average, 3.6 yr). The average main thoracic Cobb angle correction rate and the correction loss at the final follow-up were 67.8% and 3.3°, respectively. The average preoperative thoracic kyphosis (T5-T12) was 11.9°, which improved significantly to 20.5° (P < 0.0001) at the final follow-up. An increase in thoracic kyphosis was significantly correlated with an increase in lumbar lordosis at the final follow-up (r = 0.42). The average preoperative vertebral rotation angle was 19.7°, which improved significantly after surgery to 14.9° (P = 0.0001). There was no correlation between change in thoracic kyphosis and change in apical vertebral rotation (r =-0.123). The average preoperative total Scoliosis Research Society questionnaire score was 3.0, which significantly improved to 4.4 (P < 0.0001) at the final follow-up. Throughout surgery and even after, there were no instrumentation failures, pseudarthrosis, infection of the surgical site, or clinically relevant neurovascular complications.

CONCLUSION

The simultaneous double-rod rotation technique for treating Lenke 1 AIS provides significant sagittal correction of the main thoracic curve while maintaining sagittal profiles and correcting coronal and axial deformities.

LEVEL OF EVIDENCE

4.

Sagittal spinopelvic malalignment in Parkinson disease: prevalence and associations with disease severity

STUDY DESIGN

Prospective study.

OBJECTIVE

Our objectives were to evaluate the prevalence of sagittal spinopelvic malalignment in a consecutive series of patients with Parkinson disease (PD) and to identify factors associated with sagittal spinopelvic deformity in this population.

SUMMARY OF BACKGROUND DATA

PD is a degenerative neurological condition characterized by tremor, rigidity, bradykinesia, and loss of postural reflexes. The prevalence of spinal deformity in PD is higher than that of age-matched adults without PD.

METHODS

This study was a prospective assessment of consecutive patients with PD presenting to a neurology clinic during 12 months. Inclusion criteria included age more than 21 years and diagnosis of PD. Age- and sex-matched control group was selected from patients with cervical spondylosis. Clinical and demographic factors were collected including Unified Parkinson Disease Rating Scale score and Hoehn and Yahr stage. Full-length standing spine radiographs were assessed. Patients were grouped into either low C7 sagittal vertical axis (SVA) (<5 cm) or high C7 SVA (≥5 cm) and into matched (≤10°) or mismatched (>10°) pelvic incidence (PI)-lumbar lordosis.

RESULTS

Eighty-nine patients met criteria (41 males/48 females), including 52 with low C7 SVA and 37 with high C7 SVA. Significantly higher prevalence of high C7 SVA was found in PD (41.6 vs. 16.8%; P < 0.001). The high C7 SVA group was significantly older (72.4 vs. 65.1 yr; P < 0.001) and had a higher proportion of females (68% vs. 44%; P = 0.034), greater severity of PD based on Hoehn and Yahr stage (1.89 vs. 1.37; P < 0.001) and Unified Parkinson Disease Rating Scale (30.5 vs. 17.2; P = 0.002. Unified Parkinson Disease Rating Scale significantly correlated with C7 SVA (r = 0.474). Compared with the matched (≤10°) PI-lumbar lordosis group, the mismatch PI-lumbar lordosis group had higher C7 SVA, higher PI, higher pelvic tilt, lower lumbar lordosis, and lower thoracic kyphosis (P ≤ 0.003).

CONCLUSION

Patients with PD have a high prevalence of sagittal spinopelvic malalignment than control group patients. Greater severity of PD is associated with sagittal spinopelvic malalignment.

LEVEL OF EVIDENCE

3.

Minimally invasive surgical techniques in adult degenerative spinal deformity: a systematic review

BACKGROUND

Minimally invasive surgery (MIS) approaches have the potential to reduce procedure-related morbidity when compared with traditional approaches. However, the magnitude of radiographic correction and degree of clinical improvement with MIS techniques for adult spinal deformity remain undefined.

QUESTION/PURPOSES

In this systematic review, we sought to determine whether MIS approaches to adult spinal deformity correction (1) improve pain and function; (2) reliably correct deformity and result in fusion; and (3) are safe with respect to surgical and medical complications.

METHODS

A systematic review of PubMed and Medline databases was performed for published articles from 1950 to August 2013. A total of 1053 papers were identified. Thirteen papers were selected based on prespecified criteria, including a total of 262 patients. Studies with limited short-term followup (mean, 12.1 months; range, 1.5-39 months) were included to capture early complications. All of the papers included in the review constituted Level IV evidence. Patient age ranged from 20 to 86 years with a mean of 65.8 years. Inclusion and exclusion criteria were variable, but all required at minimum a diagnosis of adult degenerative scoliosis.

RESULTS

Four studies demonstrated improvement in leg/back visual analog scale, three demonstrated improvement in the Oswestry Disability Index, one demonstrated improvement in treatment intensity scale, and one improvement in SF-36. Reported fusion rates ranged from 71.4% to 100% 1 year postoperatively, but only two of 13 papers relied consistently on CT scan to assess fusion, and, interestingly, only four of 10 studies reporting radiographic results on deformity correction found the procedures effective in correcting deformity. There were 115 complications reported among the 258 patients (46%), including 37 neurological complications (14%).

CONCLUSIONS

The literature on these techniques is scanty; only two of the 13 studies that met inclusion criteria were considered high quality; CT scans were not generally used to evaluate fusion, deformity correction was inconsistent, and complication rates were high. Future directions for analysis must include comparative trials, longer-term followup, and consistent use of CT scans to assess for fusion to determine the role of MIS techniques for adult spinal deformity.

Maintenance of radiographic correction at 2 years following lumbar pedicle subtraction osteotomy is superior with upper thoracic compared with thoracolumbar junction upper instrumented vertebra

PURPOSE

The goal of this study was to characterize the spino-pelvic realignment and the maintenance of that realignment by the upper-most instrumented vertebra (UIV) for adult deformity spinal (ASD) patients treated with lumbar pedicle subtraction osteotomy (PSO).

METHODS

ASD patients were divided by UIV, classified as upper thoracic (UT: T1-T6) or Thoracolumbar (TL: T9-L1). Complications were recorded and radiographic parameters included thoracic kyphosis (TK, T2-T12), lumbar lordosis (LL, L1-S1), sagittal vertical axis (SVA), pelvic tilt, and the mismatch between pelvic incidence and LL. Patients were also classified by the Scoliosis Research Society (SRS)-Schwab modifier grades. Changes in radiographic parameters and SRS-Schwab grades were evaluated between the two groups. Additional analyses were performed on patients with pre-operative SVA ≥ 15 cm.

RESULTS

165 patients were included (UT: 81 and TL: 84); 124 women, 41 men, with average age 59.9 ± 11.1 years (range 25-81). UT had a lower percentage of patients above the radiographic thresholds for disability than TL. UT had a significantly higher percentage of patients that improved in SRS-Schwab global alignment grade than the TL group at 2 years. Within the patients with pre-operative SVA ≥ 15 cm, TL developed significantly increased SVA and had a significantly higher percentage of patients above the SVA threshold at 3 months, and 1 and 2 years than UT.

CONCLUSIONS

Patients undergoing a single-level PSO for ASD who have fixation extending to the UT region (T1-T6) are more likely to maintain sagittal spino-pelvic alignment, lower overall revision rates and revision rate for proximal junctional kyphosis than those with fixation terminating in the TL region (T9-L1).

Revision Surgery After 3-Column Osteotomy in 335 Patients With Adult Spinal Deformity: Intercenter Variability and Risk Factors

STUDY DESIGN

Multicenter, retrospective review.

OBJECTIVE

To assess rates, site variability, and risk factors for revision surgery (RS) after 3-column osteotomy (3CO).

SUMMARY OF BACKGROUND DATA

Complex spinal osteotomies, including 3CO, are being increasingly performed in the setting of patients with adult spinal deformity with sagittal plane deformity. Three-column osteotomy procedures are associated with high complication and RS rates, but risk factors for complications and variability across centers for revision have not been well defined.

METHODS

The incidence and indications for RS in 335 patients with adult spinal deformity were analyzed. RS indications were classified as "mechanical" (MR: implant failure, pseudarthrosis, junctional failure, and loss/lack of correction) or "nonmechanical" (NMR: neurological deficit, infection, wound dehiscence, and stenosis). Risks factors for RS were analyzed using generalized linear models.

RESULTS

Three-month and 1-year RS incidences were 12.3% and 17.6%, respectively. Single-level 3CO (n = 311) had lower RS rates than multilevel 3CO (n = 24, 15.8% vs. 41.7%, P = 0.001). The 16.7% rate for single-level lumbar 3CO included 11.4% for MR and 5.7% for NMR. For all RS, 50% of MR and 78.6% of NMR occurred within 3 months of the index surgery. There was significant variation in rates across sites (range = 6.3%-31.9%, P = 0.001), however low- and high-volume sites had similar rates (18.2% vs. 16.2%, P = 0.503). Patients with MR were more likely to be sagittally undercorrected at 3 months (sagittal vertical axis = 7 cm vs. 3.2 cm, P = 0.003). Patients with NMR had more caudal 3CO levels (L4 vs. L3, P = 0.014) and larger 3CO bone resections than patients who did not (34°vs. 24.5°, P = 0.003).

CONCLUSION

Three-column osteotomy procedures for adult spinal deformity surgery can provide significant deformity correction and lead to marked improvement in function despite established complication and revision rates. This study shows that RS is associated with lower level osteotomy and higher residual sagittal vertical axis. There is significant variability in revision rates across sites independent of site volume, suggesting potential systems and practice variations that warrant further study.

LEVEL OF EVIDENCE

4.