Category: Spine

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Practical answers to frequently asked questions for shared decision-making in adult spinal deformity surgery

J Neurosurg Spine 34:218–227, 2021

The shared decision-making (SDM) process provides an opportunity to answer frequently asked questions (FAQs). The authors aimed to present a concise list of answers to FAQs to aid in SDM for adult spinal deformity (ASD) surgery.

METHODS From a prospective, multicenter ASD database, patients enrolled between 2008 and 2016 who underwent fusions of 5 or more levels with a minimum 2-year follow-up were included. All deformity types were included to provide general applicability. The authors compiled a list of FAQs from patients undergoing ASD surgery and used a retrospective analysis to provide answers. All responses are reported as either the means or the proportions reaching the minimal clinically important difference at the 2-year follow-up interval.

RESULTS Of 689 patients with ASD who were eligible for 2-year follow-up, 521 (76%) had health-related quality-of-life scores available at the time of that follow-up. The mean age at the initial surgery was 58.2 years, and 78% of patients were female. The majority (73%) underwent surgery with a posterior-only approach. The mean number of fused levels was 12.2. Revision surgery accounted for 48% of patients. The authors answered 12 FAQs as follows:

1. Will my pain improve? Back and leg pain will both be reduced by approximately 50%.

2. Will my activity level improve? Approximately 65% of patients feel improvement in their activity level.

3. Will I feel better about myself? More than 70% of patients feel improvement in their appearance.

4. Is there a chance I will get worse? 4.1% feel worse at 2 years postoperatively.

5. What is the likelihood I will have a complication? 67.8% will have a major or minor complication, with 47.8% having a major complication.

6. Will I need another surgery? 25.0% will have a reoperation within 2 years.

7. Will I regret having surgery? 6.5% would not choose the same treatment.

8. Will I get a blood transfusion? 73.7% require a blood transfusion.

9. How long will I stay in the hospital? You need to stay 8.1 days on average.

10. Will I have to go to the ICU? 76.0% will have to go to the ICU.

11. Will I be able to return to work? More than 70% will be working at 1 year postoperatively.

12. Will I be taller after surgery? You will be 1.1 cm taller on average.

CONCLUSIONS The above list provides concise, practical answers to FAQs encountered in the SDM process while counseling patients for ASD surgery.

 

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Mild and Severe Obesity Reduce the Effectiveness of Lumbar Fusions

Neurosurgery 88 (2) 2021: 285–294

Elevated body mass index (BMI) is a well-known risk factor for surgical complications in lumbar surgery. However, its effect on surgical effectiveness independent of surgical complications is unclear.

OBJECTIVE: To determine increasing BMI’s effect on functional outcomes following lumbar fusion surgery, independent of surgical complications.

METHODS:We retrospectively analyzed a prospectively built, patient-reported, quality of life registry representing 75 hospital systems. We evaluated 1- to 3-level elective lumbar fusions. Patients who experienced surgical complicationswere excluded. A stepwisemultivariate regression model assessed factors independently associated with 1-yr Oswestry Disability Index (ODI), preop to 1-yr ODI change, and achievement of minimal clinically important difference (MCID).

RESULTS: A total of 8171 patients met inclusion criteria: 2435 with class I obesity (BMI 30- 35 kg/m2), 1328 with class II (35-40 kg/m2), and 760 with class III (≥40 kg/m2). Increasing BMI was independently associated with worse 12-mo ODI (t = 8.005, P < .001) and decreased likelihood of achieving MCID (odds ratio [OR] = 0.977, P < .001). One year after surgery, mean ODI, ODI change, and percentage achieving MCID worsened with class I, class II, and class III vs nonobese cohorts (P < .001) in stepwise fashion.

CONCLUSION: Increasing BMI is associated with decreased effectiveness of 1- to 3-level elective lumbar fusion, despite absence of surgical complications. BMI ≥ 30 kg/m2 is, therefore, a risk factor for both surgical complication and reduced benefit from lumbar fusion.

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Is the Goutallier grade of multifidus fat infiltration associated with adjacent-segment degeneration after lumbar spinal fusion?

J Neurosurg Spine 34:190–195, 2021

The aim of this study was to investigate whether fat infiltration of the lumbar multifidus (LM) muscle affects revision surgery rates for adjacent-segment degeneration (ASD) after L4–5 transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis.

METHODS A total of 178 patients undergoing single-level L4–5 TLIF for spondylolisthesis (2006 to 2016) were retrospectively analyzed. Inclusion criteria were a minimum 2-year follow-up, preoperative MR images and radiographs, and single-level L4–5 TLIF for degenerative spondylolisthesis. Twenty-three patients underwent revision surgery for ASD during the follow-up. Another 23 patients without ASD were matched with the patients with ASD. Demographic data, Roussouly curvature type, and spinopelvic parameter data were collected. The fat infiltration of the LM muscle (L3, L4, and L5) was evaluated on preoperative MRI using the Goutallier classification system.

RESULTS A total of 46 patients were evaluated. There were no differences in age, sex, BMI, or spinopelvic parameters with regard to patients with and those without ASD (p > 0.05). Fat infiltration of the LM was significantly greater in the patients with ASD than in those without ASD (p = 0.029). Fat infiltration was most significant at L3 in patients with ASD than in patients without ASD (p = 0.017). At L4 and L5, there was an increasing trend of fat infiltration in the patients with ASD than in those without ASD, but the difference was not statistically significant (p = 0.354 for L4 and p = 0.077 for L5).

CONCLUSIONS Fat infiltration of the LM may be associated with ASD after L4–5 TLIF for spondylolisthesis. Fat infiltration at L3 may also be associated with ASD at L3–4 after L4–5 TLIF.

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How I do it: mini invasive transforaminal lumbar interbody fusion

Acta Neurochirurgica (2021) 163:289–293

Minimally invasive approaches for lumbar fusion are aimed at reducing soft tissue injury in order to minimize surgical morbidity and facilitate recovery.

Method Applied to lumbar fusion, such an approach is described as a mini-open transforaminal lumbar interbody fusion (TLIF). Important anatomical landmarks are reviewed. Indications, advantages, and limitations are discussed, and a step-by-step description of the procedure is presented.

Results Decompression, fixation, and bone grafting can be achieved efficiently through this approach with lesser blood loss, shorter hospital stay, reduced rate of general complications, and infections as well as a lower readmission rate.

Conclusion The mini-open TLIF technique, as presented here, is a safe and efficient procedure to achieve lumbar fusion with a reduced rate of complications related to surgery.

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A single-center retrospective analysis of 3- or 4-level anterior cervical discectomy and fusion

J Neurosurg Spine 34:45–51, 2021

Anterior cervical discectomy and fusion (ACDF) is a safe and effective intervention to treat cervical spine pathology. Although these were originally performed as single-level procedures, multilevel ACDF has been performed for patients with extensive degenerative disc disease. To date, there is a paucity of data regarding outcomes related to ACDFs of 3 or more levels. The purpose of this study was to compare surgical outcomes of 3- and 4-level ACDF procedures.

METHODS The authors performed a retrospective chart review of patients who underwent 3- and 4-level ACDF at the University of Virginia Health System between January 2010 and December 2017. In patients meeting the inclusion/exclusion criteria, demographics, fusion rates, time to fusion, and reoperation rates were evaluated. Fusion was determined by < 1 mm of change in interspinous distance between individual fused vertebrae on lateral flexion/extension radiographs and lack of radiolucency between the grafts and vertebral bodies. Any procedure requiring a surgical revision was considered a failure.

RESULTS Sixty-six patients (47 with 3-level and 19 with 4-level ACDFs) met the inclusion/exclusion criteria of having at least one lateral flexion/extension radiograph series ≥ 12 months after surgery. Seventy percent of 3-level patients and 68% of 4-level patients had ≥ 24 months of follow-up. Ninety-four percent of 3-level patients and 100% of 4-level patients achieved radiographic fusion for at least 1 surgical level. Eighty-eight percent and 82% of 3- and 4-level patients achieved fusion at C3–4; 85% and 89% of 3- and 4-level patients achieved fusion at C4–5; 68% and 89% of 3- and 4-level patients achieved fusion at C5–6; 44% and 42% of 3- and 4-level patients achieved fusion at C6–7; and no patients achieved fusion at C7–T1. Time to fusion was not significantly different between levels. Revision was required in 6.4% of patients with 3-level and in 16% of patients with 4-level ACDF. The mean time to revision was 46.2 and 45.4 months for 3- and 4-level ACDF, respectively. The most common reason for revision was worsening of initial symptoms.

CONCLUSIONS The authors’ experience with long-segment anterior cervical fusions shows their fusion rates exceeding most of the reported fusion rates for similar procedures in the literature, with rates similar to those reported for short-segment ACDFs. Three-level and 4-level ACDF procedures are viable options for cervical spine pathology, and the authors’ analysis demonstrates an equivalent rate of fusion and time to fusion between 3- and 4-level surgeries.

 

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Odontoid screw placement for Anderson type II odontoid fractures: how do duration from injury to surgery and clinical and radiological factors influence the union rate? A multicenter retrospective study

J Neurosurg Spine 34:27–31, 2021

Anderson type II odontoid fractures are severe conditions, mostly affecting elderly people (≥ 70 years old). Surgery can be performed as a primary treatment or in cases of failed conservative management. This study aimed to investigate how duration from injury to surgery, as well as clinical, radiological, and surgical risk factors, may influence the union rate after anterior odontoid screw placement for Anderson type II odontoid fractures.

METHODS The authors conducted a retrospective multicenter study. Demographic, clinical, surgical, and radiological data of patients who underwent anterior odontoid screw placement for Anderson type II fractures were retrieved from institutional databases. Study exclusion criteria were prolonged corticosteroid drug therapy (> 4 weeks), polytraumatic injuries, oncological diagnosis, and prior cervical spine trauma.

RESULTS Eighty-five patients were included in the present investigation. The union rate was 76.5%, and 73 patients (85.9%) did not report residual instability. Age ≥ 70 years (p < 0.001, OR 6), female gender (p = 0.016, OR 3.61), osteoporosis (p = 0.009, OR 4.02), diabetes (p = 0.056, OR 3.35), fracture diastasis > 1 mm (p < 0.001, OR 8.5), and duration from injury to surgery > 7 days (p = 0.002, OR 48) independently influenced union rate, whereas smoking status (p = 0.677, OR 1.24) and odontoid process angulation > 10° (p = 0.885, OR 0.92) did not.

CONCLUSIONS Although many factors have been reported as influencing the union rate after anterior odontoid screw placement for Anderson type II fractures, duration from injury to surgery > 7 days appears to be the most relevant, resulting in a 48 times higher risk for nonunion. Early surgery appears to be associated with better radiological outcomes, as reported by orthopedic surgeons in other districts. Prospective comparative clinical trials are needed to confirm these results.

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Development and validation of a clinical prediction score for poor postoperative pain control following elective spine surgery

J Neurosurg Spine 34:3–12, 2021

Thirty percent to sixty-four percent of patients experience poorly controlled pain following spine surgery, leading to patient dissatisfaction and poor outcomes. Identification of at-risk patients before surgery could facilitate patient education and personalized clinical care pathways to improve postoperative pain management. Accordingly, the aim of this study was to develop and internally validate a prediction score for poorly controlled postoperative pain in patients undergoing elective spine surgery.

METHODS A retrospective cohort study was performed in adult patients (≥ 18 years old) consecutively enrolled in the Canadian Spine Outcomes and Research Network registry. All patients underwent elective cervical or thoracolumbar spine surgery and were admitted to the hospital. Poorly controlled postoperative pain was defined as a mean numeric rating scale score for pain at rest of > 4 during the first 24 hours after surgery. Univariable analysis followed by multivariable logistic regression on 25 candidate variables, selected through a systematic review and expert consensus, was used to develop a prediction model using a random 70% sample of the data. The model was transformed into an eight-tier risk-based score that was further simplified into the three-tier Calgary Postoperative Pain After Spine Surgery (CAPPS) score to maximize clinical utility. The CAPPS score was validated using the remaining 30% of the data.

RESULTS Overall, 57% of 1300 spine surgery patients experienced poorly controlled pain during the first 24 hours after surgery. Seven significant variables associated with poor pain control were incorporated into a prediction model: younger age, female sex, preoperative daily use of opioid medication, higher preoperative neck or back pain intensity, higher Patient Health Questionnaire–9 depression score, surgery involving ≥ 3 motion segments, and fusion surgery. Notably, minimally invasive surgery, body mass index, and revision surgery were not associated with poorly controlled pain. The model was discriminative (C-statistic 0.74, 95% CI 0.71–0.77) and calibrated (Hosmer-Lemeshow goodness-of-fit, p = 0.99) at predicting the outcome. Low-, high-, and extreme-risk groups stratified using the CAPPS score had 32%, 63%, and 85% predicted probability of experiencing poorly controlled pain, respectively, which was mirrored closely by the observed incidence of 37%, 62%, and 81% in the validation cohort.

CONCLUSIONS Inadequate pain control is common after spine surgery. The internally validated CAPPS score based on 7 easily acquired variables accurately predicted the probability of experiencing poorly controlled pain after spine surgery.

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Thoracolumbar Junction Orientation: A Novel Guide for Sagittal Correction and Proximal Junctional Kyphosis Prediction in Adult Spinal Deformity Patients

Neurosurgery (88), Issue 1, 2021:  55–62

Novel radiographic sagittal parameters of the thoracolumbar junction orientation (TLJO, thoracolumbar slope [TLS] and thoracolumbar tilt [TLT]) have been introduced and correlated with lumbopelvic parameters and thoracic kyphosis.

OBJECTIVE: To determine a predictive model for reciprocal thoracic kyphosis and proximal junctional kyphosis (PJK) based on the TLJO.

METHODS: A total of 127 patients who had fusion from sacrum to T10-L2 from 2004 to 2014 were reviewed. TK (T5-T12), PI, SS, PT, LL, and proximal junctional angle (PJA) were measured preoperatively, 6wk postoperatively, and at final follow-up. TLJO was measured by TLS and TLT. Changes between time points were determined (preop-6 wk =ΔParameter(Pre6wk) and preop-final follow/up =ΔParameter(PreFinal)). Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) questionnaires were evaluated at final follow-up. Patients were divided into 2 groups based on the presence of PJK (PJAPreFinal >15◦). Independent t-tests and receiver operating characteristic (ROC) curves were used to investigate the significance of differences and cut-off values. Pearson correlations and linear regressions were used to analyze the entire cohort to determine the relationship between the changes in parameters.

RESULTS: Compared to patients without PJK (n = 100), those with PJK (n = 27) had significantly lower SRS scores and significantly greater TKPreFinal, LLPre6wk, and TLSPre6wk. To maintain in the nonPJK group, ROC curves demonstrated a cut-off value of −9.4◦ for TLSPre6wk. PJK was significantly correlated with TKPreFinal and TLSPre6wk. The linear correlation revealed that TLSPre6wk < −25.3◦ is the risk factor of PJK > 15◦.

CONCLUSION: As change of TLS reflects lumbopelvic realignment and influences reciprocal TK, reducing the change of TLS may be a sagittal realignment guideline to reduce the risk of PJK.

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Vertebral body fracture rates after stereotactic body radiation therapy compared with external-beam radiation therapy for metastatic spine tumors

J Neurosurg Spine 33:870–876, 2020

Stereotactic body radiation therapy (SBRT) is utilized to deliver highly conformal, dose-escalated radiation to a target while sparing surrounding normal structures. Spinal SBRT can allow for durable local control and palliation of disease while minimizing the risk of damage to the spinal cord; however, spinal SBRT has been associated with an increased risk of vertebral body fractures. This study sought to compare the fracture rates between SBRT and conventionally fractionated external-beam radiation therapy (EBRT) in patients with metastatic spine tumors.

METHODS Records from patients treated at the University of California, San Francisco, with radiation therapy for metastatic spine tumors were retrospectively reviewed. Vertebral body fracture and local control rates were compared between SBRT and EBRT. Ninety-six and 213 patients were identified in the SBRT and EBRT groups, respectively. Multivariate analysis identified the need to control for primary tumor histology (p = 0.003 for prostate cancer, p = 0.0496 for renal cell carcinoma). The patient-matched EBRT comparison group was created by matching SBRT cases using propensity scores for potential confounders, including the Spinal Instability Neoplastic Score (SINS), the number and location of spine levels treated, sex, age at treatment, duration of follow-up (in months) after treatment, and primary tumor histology. Covariate balance following group matching was confirmed using the Student t-test for unequal variance. Statistical analysis, including propensity score matching and multivariate analysis, was performed using R software and related packages.

RESULTS A total of 90 patients met inclusion criteria, with 45 SBRT and 45 EBRT matched cases. Balance of the covariates, SINS, age, follow-up time, and primary tumor histology after the matching process was confirmed between groups (p = 0.062, p = 0.174, and 0.991, respectively, along with matched tumor histology). The SBRT group had a higher 5-year rate of vertebral body fracture at 22.22% (n = 10) compared with 6.67% (n = 3) in the EBRT group (p = 0.044). Survival analysis was used to adjust for uneven follow-up time and showed a significant difference in fracture rates between the two groups (p = 0.044). SBRT also was associated with a higher rate of local control (86.67% vs 77.78%).

CONCLUSIONS Patients with metastatic cancer undergoing SBRT had higher rates of vertebral body fractures compared with patients undergoing EBRT, and this difference held up after survival analysis. SBRT also had higher rates of initial local control than EBRT but this difference did not hold up after survival analysis, most likely because of a high percentage of radiosensitive tumors in the EBRT cohort.

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Impact of sufficient contact between the autograft and endplate soon after surgery to prevent nonunion at 12 months following posterior lumbar interbody fusion

J Neurosurg Spine 33:796–805, 2020

Nonunion after posterior lumbar interbody fusion (PLIF) is associated with poor long-term outcomes in terms of health-related quality of life. Biomechanical factors in the fusion segment may influence spinal fusion rates. There are no reports on the relationship between intervertebral union and the absorption of autografts or vertebral endplates. Therefore, the purpose of this retrospective study was to evaluate the risk factors of nonunion after PLIF and identify preventive measures.

METHODS The authors analyzed 138 patients who underwent 1-level PLIF between 2016 and 2018 (75 males, 63 females; mean age 67 years; minimum follow-up period 12 months). Lumbar CT images obtained soon after the surgery and at 6 and 12 months of follow-up were examined for the mean total occupancy rate of the autograft, presence of a translucent zone between the autograft and endplate (more than 50% of vertebral diameter), cage subsidence, and screw loosening. Complete intervertebral union was defined as the presence of both upper and lower complete fusion in the center cage regions on coronal and sagittal CT slices at 12 months postoperatively. Patients were classified into either union or nonunion groups.

RESULTS Complete union after PLIF was observed in 62 patients (45%), while nonunion was observed in 76 patients (55%). The mean total occupancy rate of the autograft immediately after the surgery was higher in the union group than in the nonunion group (59% vs 53%; p = 0.046). At 12 months postoperatively, the total occupancy rate of the autograft had decreased by 5.4% in the union group and by 11.9% in the nonunion group (p = 0.020). A translucent zone between the autograft and endplate immediately after the surgery was observed in 14 and 38 patients (23% and 50%) in the union and nonunion groups, respectively (p = 0.001). The nonunion group had a significantly higher proportion of cases with cage subsidence and screw loosening at 12 months postoperatively in comparison to the union group (p = 0.010 and p = 0.009, respectively).

CONCLUSIONS A lower occupancy rate of the autograft and the presence of a translucent zone between the autograft and endplate immediately after the surgery were associated with nonunion at 12 months after PLIF. It may be important to achieve sufficient contact between the autograft and endplate intraoperatively for osseous union enhancement and to avoid excessive absorption of the autograft. The achievement of complete intervertebral union may decrease the incidence of cage subsidence or screw loosening.

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Reoperation, Readmission, and Discharge Disposition for PatientsWith Degenerative Lumbar Pathology Treated With Either Open or Minimally Invasive Techniques

Neurosurgery 2020 DOI:10.1093/neuros/nyaa246

Spine surgery has been transformed by the growth of minimally invasive surgery (MIS) procedures. Previous studies agree that MIS has shorter hospitalization and faster recovery time when compared to conventional open surgery. However, the reoperation and readmission rates between the 2 techniques have yet to be well characterized.

OBJECTIVE: To evaluate the rate of subsequent revision between MIS and open techniques for degenerative lumbar pathology.

METHODS: A total of 1435 adult patients who underwent lumbar spine surgery between 2013 and 2016were included in this retrospective analysis. The rates of need for subsequent reoperation, 30- and 90-d readmission, and discharge to rehabilitation were recorded for both MIS and traditional open techniques. Groups were divided into decompression alone and decompression with fusion.

RESULTS: The rates of subsequent reoperation following MIS and open surgerywere 10.4% and 12.2%, respectively (P = .32), which were maintained when subdivided into decompression and decompression with fusion. MIS and open 30-d readmission rates were 7.9% and 7.2% (P = .67), while 90-d readmission rates were 4.3% and 3.6% (P = .57), respectively. Discharge to rehabilitation was significantly lower for patients under 60 yr of age undergoing MIS (1.64% vs 5.63%, P = .04).

CONCLUSION: The use of minimally invasive techniques for the treatment of lumbar spine pathology does not result in increased reoperation or 30- and 90-d readmission rateswhen compared to open approaches. Patients under the age of 60 yr undergoing MIS procedures were less likely to be discharged to rehab.

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Conservative Management of Type II Odontoid Fractures in Older People

Neurosurgery 2020 DOI:10.1093/neuros/nyaa256

Type II odontoid fractures are a common cervical fracture in older people. Lower osseous-union rates are reported in those treated conservatively compared to surgically; however, the clinical relevance of a nonunion is unknown.

OBJECTIVE: To compare pain, disability, and quality of life in older people following conservativemanagement of type II odontoid fractures demonstrating osseous-union and nonunion.

METHODS: Electronic records were searched from 2008 to 2018 for adults ≥65 yr with type II odontoid fracture, managed in a semi-rigid collar. Clinical and demographic data were retrieved from electronic patient notes. Surviving patients were invited to complete questionnaires to assess pain, disability, and quality of life. Ethical approval was granted.

RESULTS: A total of 125 patients were identified: 36 (29%) demonstrated osseous-union, 89 (71%) had nonunion, of which 33 (40%) had radiological instability. Mean age at fracture was 84 yr (osseous-union 83 yr; nonunion 84 yr). A total of 53 had deceased (41 nonunion). Median length of survival was 77 mo for osseous-union vs 50 mo for nonunion; P = .02. No patient developed myelopathy during the follow-up period. Questionnaire response rate was 39 (58%). There were no statistically significant differences between the groups in terms of pain, disability, or quality of life (P>.05). Both groups reported mild disability and pain but low quality of life.

CONCLUSION: Management with a semi-rigid collar in older people with type II odontoid fracture is associated with low levels of pain and disability without statistically significant differences between those demonstrating osseous-union or stable or unstable nonunions. Conservative management appears to be a safe treatment for older people with type II fractures.

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Predictors of the Best Outcomes Following Minimally Invasive Surgery for Grade 1 Degenerative Lumbar Spondylolisthesis

Neurosurgery, 87 (6) 2020: 1130–1138

The factors driving the best outcomes following minimally invasive surgery (MIS) for grade 1 degenerative lumbar spondylolisthesis are not clearly elucidated.

OBJECTIVE: To investigate the factors that drive the best 24-mo patient-reported outcomes (PRO) following MIS surgery for grade 1 degenerative lumbar spondylolisthesis.

METHODS: A total of 259 patients from the Quality Outcomes Database lumbar spondylolisthesis module underwent single-level surgery for degenerative grade 1 lumbar spondylolisthesis with MIS techniques (188 fusions, 72.6%). Twenty-four-month follow-up PROs were collected and included the Oswestry disability index (ODI) change (ie, 24-mo minus baseline value), numeric rating scale (NRS) back pain change, NRS leg pain change, EuroQoL-5D (EQ-5D) questionnaire change, and North American Spine Society (NASS) satisfaction questionnaire. Multivariable models were constructed to identify predictors of PRO change.

RESULTS: The mean age was 64.2 ± 11.5 yr and consisted of 148 (57.1%) women and 111(42.9%) men. In multivariable analyses, employment was associated with superior postoperative ODI change (β-7.8; 95% CI [−12.9 to −2.6]; P = .003), NRS back pain change (β −1.2; 95% CI [−2.1 to −0.4]; P = .004), EQ-5D change (β 0.1; 95% CI [0.01-0.1]; P = .03), and NASS satisfaction (OR = 3.7; 95% CI [1.7-8.3]; P < .001). Increasing age was associated with superior NRS leg pain change (β −0.1; 95% CI [−0.1 to −0.01]; P= .03) and NASS satisfaction (OR=1.05; 95%CI [1.01-1.09]; P=.02). Fusion surgerieswere associated with superior ODI change (β −6.7; 95% CI [−12.7 to −0.7]; P= .03), NRS back pain change (β −1.1; 95% CI [−2.1 to −0.2]; P= .02), and NASS satisfaction (OR = 3.6; 95% CI [1.6-8.3]; P= .002).

CONCLUSION: Preoperative employment and surgeries, including a fusion, were predictors of superior outcomes across the domains of disease-specific disability, back pain, leg pain, quality of life, and patient satisfaction. Increasing age was predictive of superior outcomes for leg pain improvement and satisfaction.

 

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Neurological events due to pedicle screw malpositioning with lateral fluoroscopy–guided pedicle screw insertion

J Neurosurg Spine 33:806–811, 2020

The risk of novel postoperative neurological events due to pedicle screw malpositioning in lumbar fusion surgery is minimized by using one of the several image-guided techniques for pedicle screw insertion. These techniques for guided screw insertion range from intraoperative fluoroscopy to intraoperative navigation. A practical technique consists of anatomical identification of the screw entry point followed by lateral fluoroscopy used for guidance during insertion of the screw. This technique is available in most clinics and is less expensive than intraoperative navigation. However, the safety of lateral fluoroscopy–guided pedicle screw placement with regard to novel postoperative neurological events due to screw malposition has been addressed only rarely in the literature. In this study the authors aimed to determine the rate of novel postoperative neurological events due to intraoperative and postoperatively established screw malpositioning during lateral fluoroscopy–assisted screw insertion.

METHODS Included patients underwent lateral fluoroscopy–assisted lumbosacral screw insertion between January 2012 and August 2017. The occurrence of novel postoperative neurological events was analyzed from patient files. In case of an event, surgical reports were screened for the occurrence of intraoperative screw malposition. Furthermore, postoperative CT scans were analyzed to identify and describe possible screw malposition.

RESULTS In total, 246 patients with 1079 screws were included. Novel postoperative neurological events were present in 36 patients (14.6%). In 8 of these 36 patients (3.25% of the total study population), the neurological events could be directly attributed to screw malposition. Screw malpositioning was caused either by problematic screw insertion with immediate screw correction (4 patients) or by malpositioned screws for which the malposition was established postoperatively using CT scans (4 patients). Three patients with screw malposition underwent revision surgery without subsequent symptom relief.

CONCLUSIONS Lateral fluoroscopy–assisted lumbosacral screw placement results in low rates of novel postoperative neurological events caused by screw malposition. In the majority of patients suffering from novel postoperative neurological events, these events could not be attributed to screw malpositioning, but rather were due to postoperative neurapraxia of peripheral nerves, neuropathy, or intraoperative traction of nerve roots.

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

J Neurosurg Spine 33:822–829, 2020

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

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

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

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

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Pseudarthrosis in anterior cervical discectomy and fusion with a self-locking, stand-alone cage filled with hydroxyapatite

J Neurosurg Spine 33:717–726, 2020

The goal of this study was to evaluate the incidence of pseudarthrosis after the treatment of cervical degenerative disc disease (CDDD) with anterior cervical discectomy and fusion (ACDF) in which self-locking, stand-alone intervertebral cages filled with hydroxyapatite were used.

METHODS The authors performed a retrospective cohort study of 49 patients who underwent 1- to 3-level ACDF with self-locking, stand-alone intervertebral cages without plates, with a minimum 2 years of follow-up. The following data were extracted from radiological and clinical charts: age, sex, time and type of pre- and postoperative signs and symptoms, pain status (visual analog scale [VAS]), functional status (Neck Disability Index [NDI]), history of smoking, bone quality (bone densitometry), and complications. Pseudarthrosis was diagnosed by a blinded neuroradiologist using CT scans. Clinical improvement was assessed using pre- and postoperative comparison of VAS and NDI scores. The Wilcoxon test for paired tests was used to evaluate statistical significance using a p value of < 0.05.

RESULTS Three patients (6%) developed symptomatic pseudarthrosis requiring reoperation, with only 1 patient showing clinical worsening due to pseudarthrosis, while the other 2 with pseudarthrosis had associated disc disease at an adjacent level. The rate of symptomatic pseudarthrosis according to the number of operated levels was 0% for 1 level, 8.7% (2/23 patients) for 2 levels, and 7.7% (1/13 patients) for 3 levels. The total pseudarthrosis rate (including both symptomatic and asymptomatic patients) was 16.4%. Considering the clinical outcomes, there was a significant improvement of 75.6% in neck pain and 95.7% in arm pain, as well as a 64.9% improvement in NDI scores. Complications were observed in 18.4% of patients, with adjacent-level degenerative disease being the most prevalent at 14.3%.

CONCLUSIONS ACDF with self-locking, stand-alone cages filled with a hydroxyapatite graft can be used for the surgical treatment of 1- to 3-level CDDD with clinical and radiological outcomes significantly improved after a minimum 2-year follow-up period. Comparative studies are necessary.

 

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The Effect of T1-Slope in Spinal Parameters After Cervical Disc Arthroplasty

Neurosurgery 2020 DOI:10.1093/neuros/nyaa271

Although patients with cervical kyphosis are not ideal candidates for cervical disc arthroplasty (CDA), there is a paucity of data on patients with a straight or slightly lordotic neck.

OBJECTIVE: To correlate cervical lordosis, T1-slope, and clinical outcomes of CDA.

METHODS: The study retrospectively analyzed 95 patients who underwent 1-level CDA and had 2-yr follow-up. They were divided into a high T1-slope (≥28◦) group (HTSG,n=45) and a low T1-slope (<28◦) group (LTSG, n = 50). Cervical spinal alignment parameters, including T1-slope, cervical lordosis (C2-7 Cobb angle), and segmental mobility (range of motion [ROM]) at the indexed level, were compared. The clinical outcomes were also assessed.

RESULTS: The mean T1-slope was 28.1 ± 7.0◦. After CDA, the pre- and postoperative segmental motility remained similar and cervical lordosis was preserved. All the clinical outcomes improved after CDA. The HTSG were similar to the LTSG in age, sex, segmental mobility, and clinical outcomes. However, the HTSG had higher cervical lordosis than the LTSG. Furthermore, the LTSG had increased cervical lordosis (C2-7 Cobb angle), whereas the HTSG had decreased lordosis after CDA. Patients of the LTSG, who had more improvement in cervical lordosis, had a trend toward increasing segmental mobility at the index level (ROM) than the HTSG.

CONCLUSION: In this series, T1-slope correlated well with global cervical lordosis but did not affect the segmental mobility. After CDA, the changes in cervical lordosis correlated with changes in segmental mobility. Therefore, segmental lordosis should be cautiously preserved during CDA as it could determine the mobility of the disc.

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Are There Any Risk Factors Associated with the Presence of Cauda Equina Syndrome in Symptomatic Lumbar Disk Herniation?

World Neurosurg. (2020).https://doi.org/10.1016/j.wneu.2020.05.260

Risk factors for developing cauda equina syndrome (CES) caused by lumbar disk herniation (LDH) remain controversial and have not been established yet. The aim of the study was to investigate whether there is a relationship among age, sex, body mass index (BMI), or the degree of spinal canal compromise and the presence of CES in patients undergoing lumbar microdiskectomy.

METHODS: Between 2015 and 2019, 506 patients who had an operation for LDH compressing the dural sac were prospectively identified. The “prolapse-to-canal ratio” (PCR) was calculated as a proportion of the cross-sectional area of the disk prolapse compared with the total crosssectional area of the spinal canal.

RESULTS: In total, 35 CES (6.9%) patients were identified. Multivariate logistic regression, adjusted for age, gender, BMI, and PCR, shows that only PCR was associated with the presence of CES (P < 0.001, area under the curve 0.7431). BMI was not associated with an increased risk of CES.

CONCLUSIONS: This study demonstrates a significant correlation between the size of LDH relative to size of the spinal canal and the presence of CES. A finding of LDH causing >60% obstruction of the spinal canal should be considered a red flag, and such patients need to be watched more closely.

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A high-definition 3D exoscope as an alternative to the operating microscope in spinal microsurgery

J Neurosurg Spine 33:705–714, 2020

Since the 1970s, the operating microscope (OM) has been a standard for visualization and illumination of the surgical field in spinal microsurgery. However, due to its limitations (e.g., size, costliness, and the limited movability of the binocular lenses, in addition to discomfort experienced by surgeons due to the posture required), there are efforts to replace the OM with exoscopic video telescopes. The authors evaluated the feasibility of a new 3D exoscope as an alternative to the OM in spine surgeries.

METHODS Patients with degenerative pathologies scheduled for single-level lumbar or cervical spinal surgery with use of a high-definition 3D exoscope were enrolled in a prospective cohort study between January 2019 and September 2019. Age-, sex-, body mass index–, and procedure-matched patients surgically treated with the assistance of the OM served as the control group. Operative baseline and postoperative outcome parameters were assessed. Periprocedural handling, visualization, and illumination by the exoscope, as well as surgeons’ comfort level in terms of posture, were scored using a questionnaire.

RESULTS A 3D exoscope was used in 40 patients undergoing lumbar posterior decompression (LPD) and 20 patients undergoing anterior cervical discectomy and fusion (ACDF); an equal number of controls in whom an OM was used were studied. Compared with controls, there were no significant differences for mean operative time (ACDF: 132 vs 116 minutes; LPD: 112 vs 113 minutes) and blood loss (ACDF: 97 vs 93 ml; LPD: 109 vs 55 ml) as well as postoperative improvement of symptoms (ACDF/Neck Disability Index: p = 0.43; LPD/Oswestry Disability Index: p = 0.76). No intraoperative complications occurred in either group. According to the attending surgeon, the intraoperative handling of instruments was rated to be comparable to that of the OM, while the comfort level of the surgeon’s posture intraoperatively (especially during “undercutting” procedures) was rated as superior. In cases of ACDF procedures and long approaches, depth perception, image quality, and illumination were rated as inferior when compared with the OM. By contrast, for operating room nursing staff participating in 3D exoscope procedures, the visualization of intraoperative process flow and surgical situs was rated to be superior to the OM, especially for ACDF procedures.

CONCLUSIONS A 3D exoscope seems to be a safe alternative for common spinal procedures with the unique advantage of excellent comfort for the surgical team, but the drawback is the still slightly inferior visualization/illumination quality compared with the OM.

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Crossing the Cervicothoracic Junction During Posterior Cervical Fusion for Myelopathy Is AssociatedWith Superior Radiographic Parameters But Similar Clinical Outcomes

Neurosurgery 2020 DOI:10.1093/neuros/nyaa241

For laminectomy and posterior spinal fusion (LPSF) surgery for cervical spondyloticmyelopathy (CSM), the evidence is unclear as to whether fusions should cross the cervicothoracic junction (CTJ). OBJECTIVE: To compare LPSF outcomes between those with and without lower instrumented vertebrae (LIV) crossing the CTJ.

METHODS: A consecutive series of adults undergoing LPSF for CSM from 2012 to 2018 with a minimum of 12-mo follow-up were identified. LPSF with subaxial upper instrumented vertebrae and LIV between C6 and T2 were included. Clinical and radiographic outcomes were compared.

RESULTS: A total of 79 patients were included: 46 crossed the CTJ (crossed-CTJ) and 33 did not. The mean follow-up was 22.2 mo (minimum: 12 mo). Crossed-CTJ had higher preoperative C2-7 sagittal vertical axis (cSVA) (33.3 ± 16.0 vs 23.8 ± 12.4 mm, P = .01) but similar preoperative cervical lordosis (CL) and CL minus T1-slope (CL minus T1-slope) (P > .05, both comparisons). The overall reoperation rate was 3.8% (crossed-CTJ: 2.2% vs notcrossed: 6.1%, P=.37). In adjusted analyses, crossed-CTJ was associated with superior cSVA (β = –9.7; P = .002), CL (β = 6.2; P = .04), and CL minus T1-slope (β = –6.6; P = .04), but longer operative times (β = 46.3; P = .001). Crossed- and not-crossed CTJ achieved similar postoperative patient-reported outcomes [Visual Analog Scale (VAS) neck pain, VAS arm pain, Nurick Grade, Modified Japanese Orthopedic Association Scale, Neck Disability Index, and EuroQol-5D] in adjusted multivariable analyses (adjusted P > .05). For the entire cohort, higher postoperative CL was associated with lower postoperative arm pain (adjusted Pearson’s r –0.1, P=.02). No postoperative cervical radiographic parameters were associated with neck pain (P > .05).

CONCLUSION: Subaxial LPSF for CSM that crossed the CTJ were associated with superior radiographic outcomes for cSVA, CL, and CL minus T1-slope, but longer operative times. There were no differences in neck pain or reoperation rate.

 

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