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Ian McCarthy, Michael O'Brien, Christopher Ames, Chessie Robinson, Thomas Errico, David W. Polly Jr. and Richard Hostin

Object

Incremental cost-effectiveness analysis is critical to the efficient allocation of health care resources; however, the incremental cost-effectiveness ratio (ICER) of surgical versus nonsurgical treatment for adult spinal deformity (ASD) has eluded the literature, due in part to inherent empirical difficulties when comparing surgical and nonsurgical patients. Using observed preoperative health-related quality of life (HRQOL) for patients who later underwent surgery, this study builds a statistical model to predict hypothetical quality-adjusted life years (QALYs) without surgical treatment. The analysis compares predicted QALYs to observed postoperative QALYs and forms the resulting ICER.

Methods

This was a single-center (Baylor Scoliosis Center) retrospective analysis of consecutive patients undergoing primary surgery for ASD. Total costs (expressed in 2010 dollars) incurred by the hospital for each episode of surgical care were collected from administrative data and QALYs were calculated from the 6-dimensional Short-Form Health Survey, each discounted at 3.5% per year. Regression analysis was used to predict hypothetical QALYs without surgery based on preoperative longitudinal data for 124 crossover surgical patients with similar diagnoses, baseline HRQOL, age, and sex compared with the surgical cohort. Results were projected through 10-year follow-up, and the cost-effectiveness acceptability curve (CEAC) was estimated using nonparametric bootstrap methods.

Results

Three-year follow-up was available for 120 (66%) of 181 eligible patients, who were predominantly female (89%) with average age of 50. With discounting, total costs averaged $125,407, including readmissions, with average QALYs of 1.93 at 3-year follow-up. Average QALYs without surgery were predicted to be 1.6 after 3 years. At 3- and 5-year follow-up, the ICER was $375,000 and $198,000, respectively. Projecting through 10-year follow-up, the ICER was $80,000. The 10-year CEAC revealed a 40% probability that the ICER was $80,000 or less, a 90% probability that the ICER was $90,000 or less, and a 100% probability that the ICER was less than $100,000.

Conclusions

Based on the WHO's suggested upper threshold for cost-effectiveness (3 times per capita GDP, or $140,000 in 2010 dollars), the analysis reveals that surgical treatment for ASD is cost-effective after a 10-year period based on predicted deterioration in HRQOL without surgery. The ICER well exceeds the WHO threshold at earlier follow-up intervals, highlighting the importance of the durability of surgical treatment in assessing the value of surgical intervention. Due to the study's methodology, the results are dependent on the predicted deterioration in HRQOL without surgery. As such, the results may not extend to patients whose HRQOL would remain steady without surgery. Future research should therefore pursue a direct comparison of QALYs for surgical and nonsurgical patients to better understand the cost-effectiveness of surgery for the average ASD patient.

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Virginie Lafage, Neil J. Bharucha, Frank Schwab, Robert A. Hart, Douglas Burton, Oheneba Boachie-Adjei, Justin S. Smith, Richard Hostin, Christopher Shaffrey, Munish Gupta, Behrooz A. Akbarnia and Shay Bess

Object

Sagittal spinopelvic imbalance is a major contributor to pain and disability for patients with adult spinal deformity (ASD). Preoperative planning is essential for pedicle subtraction osteotomy (PSO) candidates; however, current methods are often inaccurate because no formula to date predicts both postoperative sagittal balance and pelvic alignment. The authors of this study aimed to evaluate the accuracy of 2 novel formulas in predicting postoperative spinopelvic alignment after PSO.

Methods

This study is a multicenter retrospective consecutive PSO case series. Adults with spinal deformity (> 21 years old) who were treated with a single-level lumbar PSO for sagittal imbalance were evaluated. All patients underwent preoperative and a minimum of 6-month postoperative radiography. Two novel formulas were used to predict the postoperative spinopelvic alignment. The results predicted by the formulas were then compared with the actual postoperative radiographic values, and the formulas' ability to identify successful (sagittal vertical axis [SVA] ≤ 50 mm and pelvic tilt [PT] ≤ 25°) and unsuccessful (SVA > 50 mm or PT > 25°) outcomes was evaluated.

Results

Ninety-nine patients met inclusion criteria. The median absolute error between the predicted and actual PT was 4.1° (interquartile range 2.0°–6.4°). The median absolute error between the predicted and actual SVA was 27 mm (interquartile range 11–47 mm). Forty-one of 54 patients with a formula that predicted a successful outcome had a successful outcome as shown by radiography (positive predictive value = 0.76). Forty-four of 45 patients with a formula that predicted an unsuccessful outcome had an unsuccessful outcome as shown by radiography (negative predictive value = 0.98).

Conclusions

The spinopelvic alignment formulas were accurate when predicting unsuccessful outcomes but less reliable when predicting successful outcomes. The preoperative surgical plan should be altered if an unsuccessful result is predicted. However, even after obtaining a predicted successful outcome, surgeons should ensure that the predicted values are not too close to unsuccessful values and should identify other variables that may affect alignment. In the near future, it is anticipated that the use of these formulas will lead to better surgical planning and improved outcomes for patients with complex ASD.

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Frank J. Schwab, Ashish Patel, Christopher I. Shaffrey, Justin S. Smith, Jean-Pierre Farcy, Oheneba Boachie-Adjei, Richard A. Hostin, Robert A. Hart, Behrooz A. Akbarnia, Douglas C. Burton, Shay Bess and Virginie Lafage

Object

Pedicle subtraction osteotomy (PSO) is a surgical procedure that is frequently performed on patients with sagittal spinopelvic malalignment. Although it allows for substantial spinopelvic realignment, suboptimal realignment outcomes have been reported in up to 33% of patients. The authors' objective in the present study was to identify differences in radiographic profiles and surgical procedures between patients achieving successful versus failed spinopelvic realignment following PSO.

Methods

This study is a multicenter retrospective consecutive PSO case series. The authors evaluated 99 cases involving patients who underwent PSO for sagittal spinopelvic malalignment. Because precise cutoffs of acceptable residual postoperative sagittal vertical axis (SVA) values have not been well defined, comparisons were focused between patient groups with a postoperative SVA that could be clearly considered either a success or a failure. Only cases in which the patients had a postoperative SVA of less than 50 mm (successful PSO realignment) or more than 100 mm (failed PSO realignment) were included in the analysis. Radiographic measures and PSO parameters were compared between successful and failed PSO realignments.

Results

Seventy-nine patients met the inclusion criteria. Successful realignment was achieved in 61 patients (77%), while realignment failed in 18 (23%). Patients with failed realignment had larger preoperative SVA (mean 217.9 vs 106.7 mm, p < 0.01), larger pelvic tilt (mean 36.9° vs 30.7°, p < 0.01), larger pelvic incidence (mean 64.2° vs 53.7°, p < 0.01), and greater lumbar lordosis–pelvic incidence mismatch (−47.1° vs −30.9°, p < 0.01) compared with those in whom realignment was successful. Failed and successful realignments were similar regarding the vertebral level of the PSO, the median size of wedge resection 22.0° (interquartile range 16.5°−28.5°), and the numerical changes in pre- and postoperative spinopelvic parameters (p > 0.05).

Conclusions

Patients with failed PSO realignments had significantly larger preoperative spinopelvic deformity than patients in whom realignment was successful. Despite their apparent need for greater correction, the patients in the failed realignment group only received the same amount of correction as those in the successfully realigned patients. A single-level standard PSO may not achieve optimal outcome in patients with high preoperative spinopelvic sagittal malalignment. Patients with large spinopelvic deformities should receive larger osteotomies or additional corrective procedures beyond PSOs to avoid undercorrection.

Free access

Kseniya Slobodyanyuk, Caroline E. Poorman, Justin S. Smith, Themistocles S. Protopsaltis, Richard Hostin, Shay Bess, Gregory M. Mundis Jr., Frank J. Schwab and Virginie Lafage

Object

The goal of this study was to determine the outcome and risk factors in patients with adult spinal deformity (ASD) who elected to receive nonoperative care.

Methods

In this retrospective study the authors reviewed a nonoperative branch of the International Spine Study Group database, derived from 10 sites across the US. Specific inclusion criteria included nonoperative treatment for ASD and the availability of Scoliosis Research Society (SRS)-22 scores and radiographic data at baseline (BL) and at 1-year (1Y) follow-up. Health-related quality of life measures were assessed using the SRS-22 and radiographic data. Changes in SRS-22 scores were evaluated by domain and expressed in number of minimum clinically important differences (MCIDs) gained or lost; BL and 1Y scores were also compared with age- and sex-matched normative references.

Results

One hundred eighty-nine patients (mean age 53 years, 86% female) met inclusion criteria. Pain was the domain with the largest offset for 43% of patients, followed by the Appearance (23%), Activity (18%), and Mental (15%) domains. On average, patients improved 0.3 MCID in Pain over 1Y, without changes in Activity or Appearance. Baseline scores significantly impacted 1Y outcomes, with up to 85% of patients in the mildest category of deformity being classified as < 1 MCID of normative reference at 1Y, versus 0% of patients with the most severe initial deformity. Baseline radiographic parameters did not correlate with outcome.

Conclusions

Patients who received nonoperative care are significantly more disabled than age- and sex-matched normative references. The likelihood for a patient to reach SRS scores similar to the normative reference at 1Y decreases with increased BL disability. Nonoperative treatment is a viable option for certain patients with ASD, and up to 24% of patients demonstrated significant improvement over 1Y with nonoperative care.

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Justin K. Scheer, Jessica A. Tang, Justin S. Smith, Eric Klineberg, Robert A. Hart, Gregory M. Mundis Jr., Douglas C. Burton, Richard Hostin, Michael F. O'Brien, Shay Bess, Khaled M. Kebaish, Vedat Deviren, Virginie Lafage, Frank Schwab, Christopher I. Shaffrey, Christopher P. Ames and the International Spine Study Group

Object

Complications and reoperation for surgery to correct adult spinal deformity are not infrequent, and many studies have analyzed the rates and factors that influence the likelihood of reoperation. However, there is a need for more comprehensive analyses of reoperation in adult spinal deformity surgery from a global standpoint, particularly focusing on the 1st year following operation and considering radiographic parameters and the effects of reoperation on health-related quality of life (HRQOL). This study attempts to determine the prevalence of reoperation following surgery for adult spinal deformity, assess the indications for these reoperations, evaluate for a relation between specific radiographic parameters and the need for reoperation, and determine the potential impact of reoperation on HRQOL measures.

Methods

A retrospective review was conducted of a prospective, multicenter, adult spinal deformity database collected through the International Spine Study Group. Data collected included age, body mass index, sex, date of surgery, information regarding complications, reoperation dates, length of stay, and operation time. The radiographic parameters assessed were total number of levels instrumented, total number of interbody fusions, C-7 sagittal vertical axis, uppermost instrumented vertebra (UIV) location, and presence of 3-column osteotomies. The HRQOL assessment included Oswestry Disability Index (ODI), 36-Item Short Form Health Survey physical component and mental component summary, and SRS-22 scores. Smoking history, Charlson Comorbidity Index scores, and American Society of Anesthesiologists Physical Status classification grades were also collected and assessed for correlation with risk of early reoperation. Various statistical tests were performed for evaluation of specific factors listed above, and the level of significance was set at p < 0.05.

Results

Fifty-nine (17%) of a total of 352 patients required reoperation. Forty-four (12.5%) of the reoperations occurred within 1 year after the initial surgery, including 17 reoperations (5%) within 30 days.

Two hundred sixty-eight patients had a minimum of 1 year of follow-up. Fifty-three (20%) of these patients had a 3-column osteotomy, and 10 (19%) of these 53 required reoperation within 1 year of the initial procedure. However, 3-column osteotomy was not predictive of reoperation within 1 year, p = 0.5476). There were no significant differences between groups with regard to the distribution of UIV, and UIV did not have a significant effect on reoperation rates. Patients needing reoperation within 1 year had worse ODI and SRS-22 scores measured at 1-year follow-up than patients not requiring operation.

Conclusions

Analysis of data from a large multicenter adult spinal deformity database shows an overall 17% reoperation rate, with a 19% reoperation rate for patients treated with 3-column osteotomy and a 16% reoperation rate for patients not treated with 3-column osteotomy. The most common indications for reoperation included instrumentation complications and radiographic failure. Reoperation significantly affected HRQOL outcomes at 1-year follow-up. The need for reoperation may be minimized by carefully considering spinal alignment, termination of fixation, and type of surgical procedure (presence of osteotomy). Precautions should be taken to avoid malposition or instrumentation (rod) failure.

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Joshua Bakhsheshian, Justin K. Scheer, Jeffrey L. Gum, Richard Hostin, Virginie Lafage, Shay Bess, Themistocles S. Protopsaltis, Douglas C. Burton, Malla Kate Keefe, Robert A. Hart, Gregory M. Mundis Jr., Christopher I. Shaffrey, Frank Schwab, Justin S. Smith, Christopher P. Ames and The International Spine Study Group

OBJECTIVE

Mental disease burden can have a significant impact on levels of disability and health-related quality of life (HRQOL) measures. Therefore, the authors investigated the significance of mental health status in adults with spinal deformity and poor physical function.

METHODS

A retrospective analysis of a prospective multicenter database of 365 adult spinal deformity (ASD) patients who had undergone surgical treatment was performed. Health-related QOL variables were examined preoperatively and at the 2-year postoperative follow-up. Patients were grouped by their 36-Item Short Form Health Survey mental component summary (MCS) and physical component summary (PCS) scores. Both groups had PCS scores ≤ 25th percentile for matched norms; however, the low mental health (LMH) group consisted of patients with an MCS score ≤ 25th percentile, and the high mental health (HMH) group included patients with an MCS score ≥ 75th percentile.

RESULTS

Of the 264 patients (72.3%) with a 2-year follow-up, 104 (28.5%) met the inclusion criteria for LMH and 40 patients (11.0%) met those for HMH. The LMH group had a significantly higher overall rate of comorbidities, specifically leg weakness, depression, hypertension, and self-reported neurological and psychiatric disease processes, and were more likely to be unemployed as compared with the HMH group (p < 0.05 for all). The 2 groups had similar 2-year postoperative improvements in HRQOL (p > 0.05) except for the greater improvements in the MCS and the Scoliosis Research Society-22r questionnaire (SRS-22r) mental domain (p < 0.05) in the LMH group and greater improvements in PCS and SRS-22r satisfaction and back pain domains (p < 0.05) in the HMH group. The LMH group had a higher rate of reaching a minimal clinically important difference (MCID) on the SRS-22r mental domain (p < 0.01), and the HMH group had a higher rate of reaching an MCID on the PCS and SRS-22r activity domain (p < 0.05). On multivariable logistic regression, having LMH was a significant independent predictor of failure to reach an MCID on the PCS (p < 0.05). At the 2-year postoperative follow-up, 14 LMH patients (15.1%) were categorized as HMH. Two LMH patients (2.2%), and 3 HMH patients (7.7%) transitioned to a PCS score ≥ 75th percentile for age- and sex-matched US norms (p < 0.01).

CONCLUSIONS

While patients with poor mental and physical health, according to their MCS and PCS scores, have higher medical comorbidity and unemployment rates, they still demonstrate significant improvements in HRQOL measurements postoperatively. Both LMH and HMH patient groups demonstrated similar improvements in most HRQOL domains, except that the LMH patients had difficulties in obtaining improvements in the PCS domain.

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Alex Soroceanu, Douglas C. Burton, Bassel Georges Diebo, Justin S. Smith, Richard Hostin, Christopher I. Shaffrey, Oheneba Boachie-Adjei, Gregory M. Mundis Jr., Christopher Ames, Thomas J. Errico, Shay Bess, Munish C. Gupta, Robert A. Hart, Frank J. Schwab, Virginie Lafage and International Spine Study Group

OBJECT

Adult spinal deformity (ASD) surgery is known for its high complication rate. This study examined the impact of obesity on complication rates, infection, and patient-reported outcomes in patients undergoing surgery for ASD.

METHODS

This study was a retrospective review of a multicenter prospective database of patients with ASD who were treated surgically. Patients with available 2-year follow-up data were included. Obesity was defined as having a body mass index (BMI) ≥ 30 kg/m2. Data collected included complications (total, minor, major, implant-related, radiographic, infection, revision surgery, and neurological injury), estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), and patient-reported questionnaires (Oswestry Disability Index [ODI], Short Form-36 [SF-36], and Scoliosis Research Society [SRS]) at baseline and at 6 weeks, 1 year, and 2 years postoperatively. The impact of obesity was studied using multivariate modeling, accounting for confounders.

RESULTS

Of 241 patients who satisfied inclusion criteria, 175 patients were nonobese and 66 were obese. Regression models showed that obese patients had a higher overall incidence of major complications (IRR 1.54, p = 0.02) and wound infections (odds ratio 4.88, p = 0.02). Obesity did not increase the number of minor complications (p = 0.62), radiographic complications (p = 0.62), neurological complications (p = 0.861), or need for revision surgery (p = 0.846). Obesity was not significantly correlated with OR time (p = 0.23), LOS (p = 0.9), or EBL (p = 0.98). Both groups experienced significant improvement overtime, as measured on the ODI (p = 0.0001), SF-36 (p = 0.0001), and SRS (p = 0.0001) questionnaires. However, the overall magnitude of improvement was less for obese patients (ODI, p = 0.0035; SF-36, p = 0.0012; SRS, p = 0.022). Obese patients also had a lower rate of improvement over time (SRS, p = 0.0085; ODI, p = 0.0001; SF-36, p = 0.0001).

CONCLUSIONS

This study revealed that obese patients have an increased risk of complications following ASD correction. Despite these increased complications, obese patients do benefit from surgical intervention; however, their improvement in health-related quality of life (HRQL) is less than that of nonobese patients.

Free access

Taemin Oh, Justin K. Scheer, Justin S. Smith, Richard Hostin, Chessie Robinson, Jeffrey L. Gum, Frank Schwab, Robert A. Hart, Virginie Lafage, Douglas C. Burton, Shay Bess, Themistocles Protopsaltis, Eric O. Klineberg, Christopher I. Shaffrey, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

Patients with adult spinal deformity (ASD) experience significant quality of life improvements after surgery. Treatment, however, is expensive and complication rates are high. Predictive analytics has the potential to use many variables to make accurate predictions in large data sets. A validated minimum clinically important difference (MCID) model has the potential to assist in patient selection, thereby improving outcomes and, potentially, cost-effectiveness.

METHODS

The present study was a retrospective analysis of a multiinstitutional database of patients with ASD. Inclusion criteria were as follows: age ≥ 18 years, radiographic evidence of ASD, 2-year follow-up, and preoperative Oswestry Disability Index (ODI) > 15. Forty-six variables were used for model training: demographic data, radiographic parameters, surgical variables, and results on the health-related quality of life questionnaire. Patients were grouped as reaching a 2-year ODI MCID (+MCID) or not (−MCID). An ensemble of 5 different bootstrapped decision trees was constructed using the C5.0 algorithm. Internal validation was performed via 70:30 data split for training/testing. Model accuracy and area under the curve (AUC) were calculated. The mean quality-adjusted life years (QALYs) and QALYs gained at 2 years were calculated and discounted at 3.5% per year. The QALYs were compared between patients in the +MCID and –MCID groups.

RESULTS

A total of 234 patients met inclusion criteria (+MCID 129, −MCID 105). Sixty-nine patients (29.5%) were included for model testing. Predicted versus actual results were 50 versus 40 for +MCID and 19 versus 29 for −MCID (i.e., 10 patients were misclassified). Model accuracy was 85.5%, with 0.96 AUC. Predicted results showed that patients in the +MCID group had significantly greater 2-year mean QALYs (p = 0.0057) and QALYs gained (p = 0.0002).

CONCLUSIONS

A successful model with 85.5% accuracy and 0.96 AUC was constructed to predict which patients would reach ODI MCID. The patients in the +MCID group had significantly higher mean 2-year QALYs and QALYs gained. This study provides proof of concept for using predictive modeling techniques to optimize patient selection in complex spine surgery.

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Virginie Lafage, Frank Schwab, Shaleen Vira, Robert Hart, Douglas Burton, Justin S. Smith, Oheneba Boachie-Adjei, Alexis Shelokov, Richard Hostin, Christopher I. Shaffrey, Munish Gupta, Behrooz A. Akbarnia, Shay Bess and Jean-Pierre Farcy

Object

Pedicle subtraction osteotomy (PSO) is a spinal realignment technique that may be used to correct sagittal spinal imbalance. Theoretically, the level and degree of resection via a PSO should impact the degree of sagittal plane correction in the setting of deformity. However, the quantitative effect of PSO level and focal angular change on postoperative spinopelvic parameters has not been well described. The purpose of this study is to analyze the relationship between the level/degree of PSO and changes in global sagittal balance and spinopelvic parameters.

Methods

In this multicenter retrospective study, 70 patients (54 women and 16 men) underwent lumbar PSO surgery for spinal imbalance. Preoperative and postoperative free-standing sagittal radiographs were obtained and analyzed by regional curves (lumbar, thoracic, and thoracolumbar), pelvic parameters (pelvic incidence and pelvic tilt [PT]) and global balance (sagittal vertical axis [SVA] and T-1 spinopelvic inclination). Correlations between PSO parameters (level and degree of change in angle between the 2 adjacent vertebrae) and spinopelvic measurements were analyzed.

Results

Pedicle subtraction osteotomy distribution by level and degree of correction was as follows: L-1 (6 patients, 24°), L-2 (15 patients, 24°), L-3 (29 patients, 25°), and L-4 (20 patients, 22°). There was no significant difference in the focal correction achieved by PSO by level. All patients demonstrated changes in preoperative to postoperative parameters including increased lumbar lordosis (from 20° to 49°, p < 0.001), increased thoracic kyphosis (from 30° to 38°, p < 0.001), decreased SVA and T-1 spinopelvic inclination (from 122 to 34 mm, p < 0.001 and from +3° to −4°, p < 0.001, respectively), and decreased PT (from 31° to 23°, p < 0.001). More caudal PSO was correlated with greater PT reduction (r = −0.410, p < 0.05). No correlation was found between SVA correction and PSO location. The PSO degree was correlated with change in thoracic kyphosis (r = −0.474, p < 0.001), lumbar lordosis (r = 0.667, p < 0.001), sacral slope (r = 0.426, p < 0.001), and PT (r = −0.358, p < 0.005).

Conclusions

The degree of PSO resection correlates more with spinopelvic parameters (lumbar lordosis, thoracic kyphosis, PT, and sacral slope) than PSO level. More importantly, PSO level impacts postoperative PT correction but not SVA.

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Emmanuelle Ferrero, Barthelemy Liabaud, Jensen K. Henry, Christopher P. Ames, Khaled Kebaish, Gregory M. Mundis, Richard Hostin, Munish C. Gupta, Oheneba Boachie-Adjei, Justin S. Smith, Robert A. Hart, Ibrahim Obeid, Bassel G. Diebo, Frank J. Schwab and Virginie Lafage

OBJECTIVE

Three-column osteotomy (3CO) is a demanding technique that is performed to correct sagittal spinal malalignment. However, the impact of the 3CO level on pelvic or truncal sagittal correction remains unclear. In this study, the authors assessed the impact of 3CO level and postoperative apex of lumbar lordosis on sagittal alignment correction, complications, and revisions.

METHODS

In this retrospective study of a multicenter spinal deformity database, radiographic data were analyzed at baseline and at 1- and 2-year follow-up to quantify spinopelvic alignment, apex of lordosis, and resection angle. The impact of 3CO level and apex level of lumbar lordosis on the sagittal correction was assessed. Logistic regression analyses were performed, controlling for cofounders, to investigate the effects of 3CO level and apex level on intraoperative and postoperative complications as well as on the need for subsequent revision surgery.

RESULTS

A total of 468 patients were included (mean age 60.8 years, mean body mass index 28.1 kg/m2); 70% of patients were female. The average 3CO resection angle was 25.1° and did not significantly differ with regard to 3CO level. There were no significant correlations between the 3CO level and amount of sagittal vertical axis or pelvic tilt correction. The postoperative apex level significantly correlated with greater correction of pelvic tilt (2° per more caudal level, R = −0.2, p = 0.006). Lower-level 3CO significantly correlated with revisions for pseudarthrosis (OR = 3.88, p = 0.001) and postoperative motor deficits (OR = 2.02, p = 0.026).

CONCLUSIONS

In this study, a more caudal lumbar 3CO level did not lead to greater sagittal vertical axis correction. The postoperative apex of lumbar lordosis significantly impacted pelvic tilt. 3CO levels that were more caudal were associated with more postoperative motor deficits and revisions.