Balance effort, Cone of Economy, and dynamic compensatory mechanisms in common degenerative spinal pathologies.

BACKGROUND: Changes in balance are common in individuals with spinal disorders and may cause falls. Balance efficiency, is the ability of a person to maintain their center of gravity with minimal neuromuscular energy expenditure, oftentimes referred to as Cone of Economy (CoE). CoE balance is defined by two sets of measures taken from the center of mass (CoM) and head: 1) the range-of-sway (RoS) in the coronal and sagittal planes, and 2) the overall sway distance. This allows spine caregivers to assess the severity of a patient's balance, balance pattern, and dynamic posture and record the changes following surgical intervention. Maintenance of balance requires coordination between the central nervous and musculoskeletal systems. RESEARCH QUESTION: To discern differences in balance effort values between common degenerative spinal pathologies and a healthy control group. METHODS: Three-hundred and forty patients with degenerative spinal pathologies: cervical spondylotic myelopathy (CSM), adult degenerative scoliosis (ADS), sacroiliac dysfunction (SIJD), degenerative lumbar spondylolisthesis (DLS), single-level lumbar degeneration (LD), and failed back syndrome (FBS), and 40 healthy controls were recruited. A functional balance test was performed approximately one week before surgery recorded by 3D video motion capture. RESULTS: Balance effort and compensatory mechanisms were found to be significantly greater in degenerative spinal pathologies patients compared to controls. Head and Center of Mass (CoM) overall sway ranged from 65.22 to 92.78 cm (p < 0.004) and 35.77-53.31 cm (p < 0.001), respectively in degenerative spinal pathologies patients and in comparison to controls (Head: 44.52 cm, CoM: 22.24 cm). Patients with degenerative spinal pathologies presented with greater trunk (1.61-2.98°, p < 0.038), hip (4.25-5.87°, p < 0.049), and knee (4.55-6.09°, p < 0.036) excursion when compared to controls (trunk: 0.95°, hip: 2.97°, and knee: 2.43°). SIGNIFICANCE: The results of this study indicate that patients from a wide variety of degenerative spinal pathologies similarly exhibit markedly diminished balance (and compensatory mechanisms) as indicated by increased sway on a Romberg test and a larger Cone of Economy (CoE) as compared to healthy controls. Balance effort, as measured by overall sway, was found to be approximately double in patients with degenerative spinal pathologies compared to healthy matched controls. Clinicians can compare CoE parameters among symptomatic patients from the different cohorts using the Haddas' CoE classification system to guide their postoperative prognosis.

Cone of economy classification: evolution, concept of stability, severity level, and correlation to patient-reported outcome scores.

STUDY DESIGN: A prospective cohort study OBJECTIVE: To determine a classification system for cone of economy (CoE) measurements that defines clinically significant changes in altered balance and to assess if the CoE measurements directly impacts patients reported outcome measures (PROMs). Preoperative functional data is a crucial component of determining patient disability and prognosis. The CoE has been theorized to be the foundation of biomechanical changes that leads to increased energy expenditure and disability in spine patients. PROMs have been developed to quantify the level of debilitation in spine patients but have various limitations. METHODS: A total of 423 symptomatic adult patients with spine pathology completed a series of PROMs preoperatively including VAS, ODI, Tampa Scale for Kinesiophobia (TSK), Fear and Avoidance Beliefs Questionnaire (FABQ), and Demoralization (DS). Functional balance was tested in this group using a full-body reflective marker set to measure head and center of mass (CoM) sway. RESULTS: PROMs scores were correlated with the magnitude of the CoE measurements. Patients were separated by the following proposed classification: CoM coronal sway > 1.5 cm, CoM sagittal sway > 3.0 cm, CoM total sway > 30.0 cm, head coronal sway > 3.0 cm, head sagittal sway > 6.0 cm, and head total sway > 60.0 cm. Significant differences were noted in the ODI (< 0.001), FABQ physical activity (< 0.001-0.009), DS (< 0.001-0.023), and TSK (< 0.001-0.032) across almost all planes of motion for both CoM and head sway. The ODI was most sensitive to the difference between groups across CoM and head sway planes with a mean ODI of 47.5-49.5 (p < 0.001) in the severe group versus 36.6-39.3 (p < 0.001) in the moderate group. CONCLUSIONS: By classifying CoE measurements by the cutoffs proposed, clinically significant alterations in balance can be quantified. Furthermore, this study demonstrates that across spinal pathology, higher magnitude CoE and range of sway measurements correlate with worsening PROMs. The Haddas' CoE classification system in this study helps to identify patients that may benefit from surgery and guide their postoperative prognosis.

The Effect of Surgical Decompression on Functional Balance Testing in Patients With Cervical Spondylotic Myelopathy.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: Quantify the extent of change in dynamic balance and stability in a group of patients with cervical spondylotic myelopathy (CSM) after cervical decompression surgery and to compare them with matched healthy controls. SUMMARY OF BACKGROUND DATA: CSM is a naturally progressive degenerative condition that commonly results in loss of fine motor control in the hands and upper extremities and in gait imbalance. Whereas this was previously thought of as an irreversible condition, more recent studies are demonstrating postoperative improvements in balance and stability. MATERIALS AND METHODS: Thirty subjects with symptomatic CSM and 25 matched asymptomatic controls between the ages of 45 and 75 years underwent functional balance testing using a 3D motion capture system to gather kinematic and spatiotemporal parameters. CSM subjects underwent testing 1 week before surgery and again 3 months postoperatively. RESULTS: Patients with CSM exhibited markedly diminished balance as indicated by increased sway on a Romberg test and requiring significantly more time and a wider stance to complete tandem gait tests. The surgical intervention resulted in improved balance at the 3-month postoperative time point; however, kinematic and spatiotemporal parameters did not completely normalize to the levels observed in asymptomatic controls. CONCLUSIONS: Human motion video capture can be used to robustly quantify balance parameters in the setting of CSM. Compared with healthy controls, such patients exhibited increased standing sway and poorer performance on a tandem gait task. The surgical intervention resulted in significant improvement in many of the measures of functional balance, but overall profiles had not completely returned to normal when measured 3 months after surgery. These data reinforce the importance of operative intervention in the treatment of symptomatic CSM with the goal of halting disease progress but the expectation that balance may actually improve postoperatively.

Reoperation for Proximal Adjacent Segment Pathology in Posterior Cervical Fusion Constructs that Fuse to C2 vs C3.

BACKGROUND: Few studies have described rates of proximal clinical adjacent segment pathology (CASP) after posterior cervical decompression and fusion (PCDF). OBJECTIVE: To investigate rates of proximal CASP at C2 vs C3 in PCDFs for degenerative spine disease. METHODS: A retrospective review of 380 cases of PCDF for degenerative disease with proximal constructs ending at C2 vs C3 was performed. Minimum follow-up was 12 mo. The primary outcome was proximal CASP requiring reoperation. Variable analysis included demographic, operative, and complication data. RESULTS: There were 119 patients in the C2 group and 261 in the C3 group with no significant differences in age, gender, comorbidities, presenting symptoms, or complications. Vertebral artery injury rates were 0.8% in the C2 group and 0.0% in the C3 group (P = .12). No patients in the C2 group had reoperation for proximal CASP, while 5.0% of patients in the C3 group did (P = .01). Patients with arthrodesis up to C3 had an increased risk of proximal failure when the fusion construct crossed the cervicothoracic junction (P = .03). Multivariate logistic regression analysis showed no factors that were independently associated with re-instrumentation for proximal CASP. CONCLUSION: Instrumenting to the C2 level reduces the risk for proximal CASP compared to fusion only up to C3. The type of instrumentation used at these 2 levels, form of ASP disease at C1-C2, and natural motion of the relevant proximal adjacent joint may contribute to this difference. Furthermore, within the C3 cohort, fusion across the cervicothoracic junction increased the risk for proximal CASP.

Use of Recombinant Human Bone Morphogenetic Protein-2 at the C1-C2 Lateral Articulation without Posterior Structural Bone Graft in Posterior Atlantoaxial Fusion in Adult Patients.

BACKGROUND: Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction. Although the potential advantages of recombinant human bone morphogenetic protein-2 (rhBMP-2) are well documented in the lumbar spine, its indication for C1-C2 fusion has not been well characterized. In our institution, we apply rhBMP-2 to the C1-C2 joint either alone or with hydroxyapatite, locally harvested autograft chips, and/or morselized allogenic bone graft for selected cases-without conventional posterior structural bone graft. We report the clinical outcomes of the surgical technique to elucidate its feasibility. METHODS: We performed a single-center, retrospective review of data from 2008 to 2016 and identified 69 patients who had undergone posterior atlantoaxial fusion with rhBMP-2. The clinical records of these patients were reviewed, and the baseline characteristics, operative data, and postoperative complications were collected and statistically analyzed. RESULTS: The average age of the 69 patients was 60.8 ± 4.5 years, and 55.1% were women. With an average follow-up period of 21.1 ± 4.2 months, the C1-C2 fusion rate was 94.3% (65 of 69), and the average time to fusion was 11.4 ± 2.6 months (range, 5-23). The overall reoperation rate was 10.1% (7 of 69), with instrumentation failure in 7 patients (10.1%), adjacent segment disease in 2 (2.9%), and postoperative dysphagia and dyspnea in 2 patients (2.9%). No ectopic bone formation or soft tissue edema developed. CONCLUSIONS: Although retrospective and from a single center, our study has shown that rhBMP-2 usage at the C1-C2 joint without posterior structural bone grafting is a safe and reasonable surgical option.

Minimally Invasive, Far Lateral Lumbar Microdiscectomy with Intraoperative Computed Tomography Navigational Assistance and Electrophysiological Monitoring.

BACKGROUND: Patients with far lateral disc herniation (FLDH) experience more severe pain and sensory symptoms compared with those with paracentral disc herniation. In addition, surgical intervention has both been more challenging and resulted in poorer outcomes. METHODS: We report our experience with intraoperative computed tomography (iCT) navigation-assisted minimally invasive tubular microdiscectomy via a paramedian approach with electrophysiological monitoring for precise 3-dimensional anatomical localization and early electrophysiological identification of the exiting nerve. RESULTS: Five patients presenting with weakness and pain refractory to conservative management underwent iCT navigation surgery for lumbar FLDH with electrophysiological monitoring. The mean decrease in the visual analog scale pain score was -7.1 and the modified MacNab criteria outcomes were good in 1 patient and excellent in 4 patients. CONCLUSIONS: These results from a small group of patients suggest this is a safe approach with the potential for improved outcomes in the surgical treatment of FLDH.

Lumbar disc reherniation after transforaminal lumbar endoscopic discectomy.

BACKGROUND: Transforaminal lumbar endoscopic discectomy is a minimally invasive surgical procedure that can be performed in awake patients through an incision less than 1 cm. The procedure requires very little bony removal to access the herniated disc material because the approach is through the foramen, and only a small amount of the superior articulating process is removed to access Kambin's triangle. This study describes our experience with transforaminal endoscopic lumbar decompression (TELD) for the treatment of lumbar disc herniation. We evaluate the risk for reherniation in the first year after surgery and the characteristics of the patients who experience reherniation. METHODS: We describe the technique for the transforaminal endoscopic approach to treat lumbar disc herniations. Retrospectively, a series of 141 consecutive patients, who were operated on with lumbar radiculopathy, was analyzed. We excluded patients who had previous surgery at the lumbar level, surgeries done for disease adjacent to a fusion, and surgeries done for spondylolisthesis. A total of 84 consecutive patients were included who had single level lumbar non-revision surgery and at least 1-year follow up. RESULTS: A series of 46 consecutive male and 38 female patients with an average age of 57.4 years (range, 28-87 years old) who underwent transforaminal endoscopic treatment for lumbar disc herniations between 2014 and 2016 is presented. Four patients required microdiscectomy due to reherniation at 5 months, 8 months, 9 months, and 10 months postoperatively. All the patients in the series improved immediately following their endoscopic procedures, and no patients presented with symptoms suggestive of reherniation until 5 months after their initial endoscopic surgery. Patients with reherniation tended to be young: 31, 45, 48, and 49 years of age: all less than the average patient age who underwent endoscopic surgery. CONCLUSIONS: Transforaminal endoscopic surgical access to lumbar disc herniations is an ultra-minimally invasive approach for the treatment lumbar degenerative disc disease. It allows for neural decompression by removing disc and foraminal pathology with minimal bone removal. This minimal bone removal prevents iatrogenic destabilization. However, the 1-year reherniation rate presented here is 4.7%. This suggests that the benefit of this technique may be that it is ultra-minimally invasive, but it may only be equal, not superior to microdiscectomy in its rate of reherniation.

Intraoperative Computed Tomography Navigational Assistance for Transforaminal Endoscopic Decompression of Heterotopic Foraminal Bone Formation After Oblique Lumbar Interbody Fusion.

Transforaminal endoscopic spine surgery is an emerging technique in spine surgery, but it offers 2 distinct challenges to spine surgeons looking to adopt it: 1) targeting spine pathology and 2) understanding the endoscopic anatomy visualized through the endoscope. Intraoperative computed tomography (CT)-guided navigation is also an emerging technique in spine surgery that is becoming widely adopted for its benefits in assisting surgeons in localizing pathology and guided spine instrumentation placement. In this technical note, we describe a technique that uses intraoperative CT-guided navigation concomitantly with a transforaminal endoscopic approach to decompress a L4-L5 foraminal heterotopic bone formation after an oblique lumbar interbody fusion. The addition of intraoperative CT-guided navigation proved beneficial in targeting the pathology during the procedure and ensuring that the pathology was resolved by offering postoperative CT visualization of the decompressed neural foramen.

Surgical management of spinal metastases.

INTRODUCTION: Metastatic spinal disease is a source of significant morbidity in patients with cancer. Recent advancements in adjuvant oncologic therapy has led to increased survival for many patients who harbor neoplastic disease. As a result of this, the chance of developing metastatic spinal disease over the course of a cancer patient's lifespan has increased. Symptomatic metastatic spinal disease can cause significant morbidity including severe pain, neurologic deficit, and loss of ambulation. Current treatment of these patients typically involves the use of multiple modalities, including surgery, radiation, and chemotherapy. Areas covered: An extensive literature review was performed to support the author's opinion on the matter of surgical management of spinal metastatic disease. Pubmed was utilized as a primary search engine. Expert commentary: Despite advances in chemotherapy and radiation therapy, surgery remains a mainstay in many of these patients, particularly with those with either significant metastatic spinal epidural compression or spinal instability. This review discusses the surgical management of metastatic spinal disease including a framework for decision making and technical considerations when deciding to operate on these patients.

Iatrogenic Spondylolisthesis Following Open Lumbar Laminectomy: Case Series and Review of the Literature.

OBJECTIVE: To present diagnosis and surgical management of postlaminectomy spondylolisthesis in patients without preoperative instability and a review of relevant literature. METHODS: Medical records and radiographic studies of 105 patients who underwent first-time bilateral 1- to 4-level open laminectomies for degenerative lumbar disease at a single academic institution were reviewed. Patients who initially presented with listhesis and had additional discectomy or fusion procedures were excluded. RESULTS: Of 105 patients with laminectomies across 1-4 levels, 10 patients (9.5%; 5 men and 5 women with average age of 63.0 ± 11.2 years) developed subsequent iatrogenic spondylolisthesis at the same operative levels that required reoperation. New or worsening low back pain and lower extremity pain were reported over an average period of 19.0 ± 17.5 months postoperatively. Imaging studies showed new spondylolisthesis that was not present before the index surgery, most commonly at L4-L5 level. All patients were treated surgically with posterior instrumented fusion. The average period between the first and second surgery was 32.6 ± 19.9 months. Surgical reduction of spondylolisthesis resulted in significant clinical improvement of patients' symptoms. CONCLUSIONS: In patients without overt pre-existing instability, laminectomy for lumbar stenosis can disrupt spinal stability and result in iatrogenic spondylolisthesis. The extent of decompression of the facet joints, number of levels decompressed, and preoperative disc space height can help assess the risk of postoperative spondylolisthesis. Patients who develop recurrent radiculopathy after decompressive lumbar laminectomy should be evaluated for potential iatrogenic spondylolisthesis.

Comparison Between S2-Alar-Iliac Screw Fixation and Iliac Screw Fixation in Adult Deformity Surgery: Reoperation Rates and Spinopelvic Parameters.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The S2-alar-iliac (S2AI) technique has been described as an alternative method for pelvic fixation in place of iliac screws (ISs) in spinal deformity surgery. The objective of this study was to analyze the impact of S2AI screws on radiographical outcomes, including spinopelvic parameters. METHODS: A retrospective review of 17 patients receiving ISs and 46 patients receiving S2AI screws for correction of adult spinal deformity between 2010 and 2015 with minimum 1-year follow-up was conducted. Patient data on postoperative complications, including reoperation rates and proximal junctional kyphosis (PJK), and radiographical parameters was collected and statistically analyzed. RESULTS: With mean follow-up of 21.1 months, the overall reoperation rate was significantly lower in the S2AI group than in the IS group (21.7% vs 58.8%, P = .01), but the incidence of PJK was similar (32.6% vs 35.3%, P > .99). Moreover, the time to reoperation in the IS group was significantly shorter than in the S2AI group (P = .001), and the S2AI group trended toward a longer time to reoperation due to PJK (P = .08). There was a significantly higher change in pelvic incidence (PI) in the S2AI group (-6.0°) compared with the IS group (P = .001). CONCLUSIONS: Compared with the IS technique, the S2AI technique demonstrated a lower rate of overall reoperation, a similar rate of PJK, longer time to reoperation, and possible reduction in PI. Future studies may be warranted to clarify the mechanism of these results and how they can be translated into improved patient care.

Prognostic Value of Preoperative Nurick Grade and Time with Symptoms in Patients with Cervical Myelopathy and Gait Impairment.

OBJECTIVE: To investigate the prognostic value of preoperative Nurick grade and time with symptoms for gait improvement and recovery in patients with ataxia secondary to cervical myelopathy. METHODS: A retrospective chart review of all adult patients who underwent surgical decompression for cervical myelopathy between 1996 and 2013 was performed. Only adults with a Nurick grade of at least 2 or worse were included. Outcome measures included gait improvement and recovery. RESULTS: A total of 170 patients were identified. Gait improvement and gait recovery occurred in 57.7% and 45.9% of patients, respectively. Time to improvement occurred as early as 1 month up to 24 months postoperatively. A greater preoperative Nurick grade was associated with lower odds of gait improvement (odds ratio 0.74; 95% confidence interval 0.53-0.99, P = 0.048) and gait recovery (odds ratio 0.27; 95% confidence interval 0.17-0.43, P < 0.001). The proportion of patients with symptoms for 12 months or less that experienced gait improvement was 71.2%, compared with 36.4% for patients with symptoms for over 12 months (P < 0.001). Patients with symptoms for 12 months or less had a 59.6% gait recovery rate, compared to 24.2% in patients with symptoms for over 12 months (P < 0.001). Having symptoms for over 12 months was independently associated with lower odds of improvement and recovery. CONCLUSIONS: Patients with a greater preoperative Nurick grade and symptoms for more than 12 months may have significantly lower odds of experiencing gait improvement or gait recovery after surgery for cervical myelopathy. This study's conclusion favors early intervention in patients with cervical myelopathy.

Readmissions After Surgical Resection of Metastatic Tumors of the Spine at a Single Institution.

BACKGROUND: Surgical management of spinal metastasis is complex and can be associated with significant postoperative morbidity. Analyzing readmission rates may serve as a proxy for postoperative morbidity and functional decline, allowing patients and physicians to make informed decisions about treatment. METHODS: Retrospective analysis was performed of patients with metastatic spine disease surgically treated at a tertiary center from 2003 to 2012. Patients with primary lung cancer, breast cancer, kidney cancer, bone marrow cancer, prostate cancer, gynecologic cancer, and melanoma were analyzed. Primary and secondary outcome variables were readmissions and overall survival. Multivariate Cox proportional hazards model was used to identify independent factors associated with readmissions. RESULTS: There were 159 patients analyzed. Lung, breast, and kidney represented the most common primary cancer sites, accounting for 22%, 19.5%, and 16.4%. Of patients, 56.6% had at least 1 readmission, with a 30-day readmission rate of 13.8% and 1-year readmission rate of 47.2%. Readmissions were for surgical complications (26.7%), oncologic disease progression (33.7%), and other medical reasons (36.7%). Patients with colorectal cancer had the highest number of readmissions. Patients with melanoma had more readmissions over the course of their limited postoperative survival. Overall mortality was 59.1%, with a median survival of 15.1 months. Multivariate analysis revealed age >60 years and previous radiation of the spine increased the likelihood of readmission. CONCLUSIONS: Readmissions provide an important window into understanding postoperative morbidity among patients with metastatic disease of the spine. This study offers an important starting point for understanding the nuances of patients' postoperative outcomes.

Use of S2-Alar-iliac Screws Associated With Less Complications Than Iliac Screws in Adult Lumbosacropelvic Fixation.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To compare clinical and radiographic outcomes between the S2-alar-iliac (S2AI) and the iliac screw (IS) techniques in the adult population and clarify the clinical strength of S2AI screws. SUMMARY OF BACKGROUND DATA: S2AI screws have been described as an alternative method for lumbosacropelvic fixation in place of ISs. The S2AI technique has several advantages with lower prominence, increased ability to directly connect to proximal instrumentation, less extensive dissection of tissue, and enhanced biomechanical strength over the IS technique. However, the clinical significance of these advantages remains unclear. METHODS: A single-center retrospective review of patients who underwent lumbosacropelvic fixation yielded 25 IS group patients and 65 S2AI group patients. Baseline demographic information, postoperative complications, pain and functional outcomes, and screw-related outcomes were collected. RESULTS: The S2AI group had lower rates of reoperation (8.8% vs. 48.0%, P < 0.001), surgical site infection (SSI) (1.5% vs. 44.0%, P < 0.001), wound dehiscence (1.5% vs. 36.0%, P < 0.001), and symptomatic screw prominence (0.0% vs. 12.0%, P = 0.02) than the IS group, whereas rates of L5-S1 pseudarthrosis, proximal junctional failure, and sacroiliac joint pain were similar in both groups. Statistically significant pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, age [odds ratio (OR) = 0.91, P = 0.004] and S2AI instrumentation (OR = 0.08, P < 0.001) were protective of reoperation, whereas diabetes mellitus (OR = 10.9, P = 0.03) and preoperative diagnosis of tumor (OR = 12.3, P = 0.04) were associated with SSI, and S2AI instrumentation (OR = 0.09, P < 0.001) was protective of SSI. CONCLUSION: The use of the S2AI technique over the IS technique was an independent predictor of preventing reoperation and SSI, while achieving similar clinical and functional outcomes. LEVEL OF EVIDENCE: 4.

Surgical Management of Osteoblastoma of the Spine: Case Series and Review of the Literature.

AIM: To describe the demographics, clinical and radiologic presentation, surgical considerations, and clinical outcomes associated with spinal osteoblastoma. MATERIAL AND METHODS: A spinal tumor database of 522 patients treated surgically at a single institution between January 2002 and June 2012 was analyzed and five patients with spinal osteoblastoma were identified and included in this study. Basic demographic and epidemiological data were recorded. Tumor characteristics, surgical parameters, and clinical follow-up data were noted. RESULTS: The mean follow-up was 21.9 months. There were four males and one female, and the mean age at diagnosis was 28.4 years. There was a mean reported symptom length of 26.4 months prior to diagnosis. There were three cervical lesions, one lumbar lesion, and one sacrococcygeal lesion. One patient was Enneking stage III and four patients were Enneking stage II. Based on spinal instability neoplastic score criteria, two patients were stable and three patients were potentially unstable. Four patients had intralesional gross total resections and one patient had an en bloc marginal resection. All patients remained neurologically stable or improved postoperatively. A single patient had recurrence of a previously resected osteoid osteoma with progression to osteoblastoma. CONCLUSION: Aggressive surgical resection of spinal osteoblastoma is suggested to minimize the risk of tumor recurrence, although this may still occur even with en bloc resection. Patients rarely present with preoperative spinal instability, but surgical fusion is often required due to removal of structural elements of the spine during resection. Of note, osteoid osteoma may progress to osteoblastoma in the spine despite prior resection.

S2-Alar-Iliac Screws are Associated with Lower Rate of Symptomatic Screw Prominence than Iliac Screws: Radiographic Analysis of Minimal Distance from Screw Head to Skin.

BACKGROUND: In sacropelvic fixation, the iliac screw technique offers biomechanically strong constructs, but its disadvantages include screw prominence, wound dehiscence, and postoperative pain secondary to the high profile nature. To overcome this drawback, S2-alar-iliac (S2AI) screws were developed as an alternative technique for sacropelvic fixation. This study aimed to compare the S2AI screw technique with the iliac screw technique in terms of postoperative symptomatic screw prominence. METHODS: A retrospective review of the records of sacropelvic fusion procedures performed at a single institution between October 2010 and January 2015 identified 32 patients with 72 iliac screws and 68 patients with 148 S2AI screws, and clinical and radiographic data were collected. If a patient had wound dehiscence and/or tenderness in the buttock immediately overlying a pelvic screw head postoperatively, it was defined as symptomatic screw prominence. The minimal distance from screw head to skin (MDSS) on postoperative computed tomography scans was measured for each patient to clarify the relationship between symptomatic screw prominence and MDSS. RESULTS: Mean follow-up period was 22.0 months. There was significantly more symptomatic pelvic screw prominence in the iliac screw group (11.1% vs. 1.4%, P = 0.002). MDSS ≤23 mm was the strongest predictor of symptomatic pelvic screw prominence, which yielded sensitivity of 100%, specificity of 94.1%, positive predictive value of 47.6%, and negative predictive value of 100%. CONCLUSIONS: The use of the S2AI screw technique resulted in a reduced rate of symptomatic screw prominence. MDSS ≤23 mm was the strongest predictor of symptomatic screw prominence.

Long-term clinical outcomes following 3- and 4-level anterior cervical discectomy and fusion.

OBJECTIVE The purpose of this study was to report the long-term clinical outcomes following 3- and 4-level anterior cervical discectomy and fusion (ACDF). METHODS A retrospective review of all adult neurosurgical patients undergoing elective ACDF for degenerative disease at a single institution between 1996 and 2013 was performed. Patients who underwent first-time 3- or 4-level ACDF were included; patients with previous cervical spine surgery, those undergoing anterior/posterior approaches, and those with corpectomy were excluded. Outcome measures included perioperative complication rates, fusion rates, need for revision surgery, Nurick Scores, Odom's criteria, symptom resolution, neck visual analog scale (VAS) pain score, and persistent narcotics usage. RESULTS Seventy-one patients who underwent 3-level ACDF and 26 patients who underwent 4-level ACDF were identified and followed for an average of 7.6 ± 4.2 years. There was 1 case (3.9%) of deep wound infection in the 4-level group and 1 case in the 3-level group (1.4%; p = 0.454). Postoperatively, 31% of patients in the 4-level group complained of dysphagia, compared with 12.7% in the 3-level group (p = 0.038). The fusion rate was 84.6% after 4-level ACDF and 94.4% after 3-level ACDF (p = 0.122). At last follow-up, a significantly higher proportion of patients in the 4-level group continued to have axial neck pain (53.8%) than in the 3-level group (31%; p = 0.039); the daily oral morphine equivalent dose was significantly higher in the 4-level group (143 ± 97 mg/day) than in the 3-level group (25 ± 10 mg/day; p = 0.030). Outcomes based on Odom's criteria were also different between cohorts (p = 0.044), with a significantly lower proportion of patients in the 4-level ACDF group experiencing an excellent/good outcome. CONCLUSIONS In this study, patients who underwent 4-level ACDF had significantly higher rates of dysphagia, postoperative neck pain, and postoperative narcotic usage when compared with patients who underwent 3-level ACDF. Pseudarthrosis and deep wound infection rates were also higher in the 4-level group, although this did not reach statistical significance. Additionally, a smaller proportion of patients achieved a good/excellent outcome in the 4-level group than in the 3-level group. These findings suggest a significant increase of perioperative morbidity and worsened outcomes for patients who undergo 4- versus 3-level ACDF.

Surgical Outcomes in Patients with High Spinal Instability Neoplasm Score Secondary to Spinal Giant Cell Tumors.

Study Design Retrospective review. Objective To describe the surgical outcomes in patients with high preoperative Spinal Instability Neoplastic Score (SINS) secondary to spinal giant cell tumors (GCT) and evaluate the impact of en bloc versus intralesional resection and preoperative embolization on postoperative outcomes. Methods A retrospective analysis was performed on 14 patients with GCTs of the spine who underwent surgical treatment prior to the use of denosumab. A univariate analysis was performed comparing the patient demographics, perioperative characteristics, and surgical outcomes between patients who underwent en bloc marginal (n = 6) compared with those who had intralesional (n = 8) resection. Results Six patients underwent en bloc resections and eight underwent intralesional resection. Preoperative embolization was performed in eight patients. All patients were alive at last follow-up, with a mean follow-up length of 43 months. Patients who underwent en bloc resection had longer average operative times (p = 0.0251), higher rates of early (p = 0.0182) and late (p = 0.0389) complications, and a higher rate of surgical revision (p = 0.0120). There was a 25% (2/8 patients) local recurrence rate for intralesional resection and a 0% (0/6 patients) local recurrence rate for en bloc resection (p = 0.0929). Conclusions Surgical excision of spinal GCTs causing significant instability, assessed by SINS, is associated with high intraoperative blood loss despite embolization and independent of resection method. En bloc resection requires a longer operative duration and is associated with a higher risk of complications when compared with intralesional resection. However, the increased morbidity associated with en bloc resection may be justified as it may minimize the risk of local recurrence.

Time to Surgery and Outcomes in Cauda Equina Syndrome: An Analysis of 45 Cases.

OBJECTIVE: The objective of this study is to analyze time to surgery as both a continuous and discrete variable to determine its association with outcomes in cauda equina syndrome (CES). METHODS: Patients at a single center whose medical record allowed precise calculation of time to surgery were included. CES was defined as at least four of the following: bladder dysfunction, saddle anesthesia, lower extremity weakness, lower extremity sensory disturbance, bowel dysfunction, or acute lower back or leg pain. Time to surgery was analyzed as a continuous variable using logistic and ordered logistic regression, and as a discrete variable by comparing patients treated before and after set thresholds. RESULTS: Forty-five patients were identified. Analysis of time as a continuous variable did not reveal any significant association with outcomes. A parsimonious model with adjustment for age, sex, race, acute onset of CES, saddle anesthesia, motor deficit, and bowel dysfunction at presentation was used to analyze the continuous influence of time to surgery on bladder dysfunction and an aggregate outcome of symptoms. Neither time to surgery nor any of the covariates were significantly associated with either outcome. Discrete analysis of outcomes across thresholds of 12, 24, 36, 48, 60, and 72 hours did not reveal prognostic time points. CONCLUSION: In this single-center CES series, time to surgery did not have a convincing continuous or discrete relationship with outcome. Future prospective studies are needed to determine the best timing for surgery in patients with CES.