Spinal deformity surgery in patients for whom blood transfusion is not an option: a single-center experience.

OBJECTIVE: Spinal deformity surgery is associated with significant blood loss, often requiring the transfusion of blood and/or blood products. For patients declining blood or blood products, even in the face of life-threatening blood loss, spinal deformity surgery has been associated with high rates of morbidity and mortality. For these reasons, patients for whom blood transfusion is not an option have historically been denied spinal deformity surgery. METHODS: The authors retrospectively reviewed a prospectively collected data set. All patients declining blood transfusion who underwent spinal deformity surgery at a single institution between January 2002 and September 2021 were identified. Demographics collected included age, sex, diagnosis, details of any prior surgery, and medical comorbidities. Perioperative variables included levels decompressed and instrumented, estimated blood loss, blood conservation techniques used, length of surgery, length of hospital stay, and complications from surgery. Radiographic measurements included, where appropriate, sagittal vertical axis correction, Cobb angle correction, and regional angular correction. RESULTS: Spinal deformity surgery was performed in 31 patients (18 male, 13 female) over 37 admissions. The median age at surgery was 41.2 years (range 10.9-70.1 years), and 64.5% had significant medical comorbidities. A median of 9 levels (range 5-16 levels) were instrumented per surgery, and the median estimated blood loss was 800 mL (range 200-3000 mL). Posterior column osteotomies were performed in all surgeries, and pedicle subtraction osteotomies in 6 cases. Multiple blood conservation techniques were used in all patients. Preoperative erythropoietin was administered prior to 23 surgeries, intraoperative cell salvage was used in all, acute normovolemic hemodilution was performed in 20, and perioperative administration of antifibrinolytic agents was performed in 28 surgeries. No allogenic blood transfusions were administered. Surgery was staged intentionally in 5 cases, and there was 1 unintended staging due to intraoperative blood loss from a vascular injury. There was 1 readmission for a pulmonary embolus. There were 2 minor postoperative complications. The median length of stay was 6 days (range 3-28 days). Deformity correction and the goals of surgery were achieved in all patients. Two patients underwent revision surgery during the follow-up period: one for pseudarthrosis and the other for proximal junctional kyphosis. CONCLUSIONS: With proper preoperative planning and judicious use of blood conservation techniques, spinal deformity surgery may be performed safely in patients for whom blood transfusion is not an option. The same techniques can be applied widely to the general population in order to minimize blood loss and the need for allogeneic blood transfusion.

Utility of intraoperative electromyography in placing C7 pedicle screws.

OBJECTIVE: The C7 vertebral body is morphometrically unique; it represents the transition from the subaxial cervical spine to the upper thoracic spine. It has larger pedicles but relatively small lateral masses compared to other levels of the subaxial cervical spine. Although the biomechanical properties of C7 pedicle screws are superior to those of lateral mass screws, they are rarely placed due to increased risk of neurological injury. Although pedicle screw stimulation has been shown to be safe and effective in determining satisfactory screw placement in the thoracolumbar spine, there are few studies determining its utility in the cervical spine. Thus, the purpose of this study was to determine the feasibility, clinical reliability, and threshold characteristics of intraoperative evoked electromyographic (EMG) stimulation in determining satisfactory pedicle screw placement at C7. METHODS: The authors retrospectively reviewed a prospectively collected data set. All adult patients who underwent posterior cervical decompression and fusion with placement of C7 pedicle screws at the authors' institution between January 2015 and March 2019 were identified. Demographic, clinical, neurophysiological, operative, and radiographic data were gathered. All patients underwent postoperative CT scanning, and the position of C7 pedicle screws was compared to intraoperative neurophysiological data. RESULTS: Fifty-one consecutive C7 pedicle screws were stimulated and recorded intraoperatively in 25 consecutive patients. Based on EMG findings, 1 patient underwent intraoperative repositioning of a C7 pedicle screw, and 1 underwent removal of a C7 pedicle screw. CT scans demonstrated ideal placement of the C7 pedicle screw in 40 of 43 instances in which EMG stimulation thresholds were > 15 mA. In the remaining 3 cases the trajectories were suboptimal but safe. When the screw stimulation thresholds were between 11 and 15 mA, 5 of 6 screws were suboptimal but safe, and in 1 instance was potentially dangerous. In instances in which the screw stimulated at thresholds ≤ 10 mA, all trajectories were potentially dangerous with neural compression. CONCLUSIONS: Ideal C7 pedicle screw position strongly correlated with EMG stimulation thresholds > 15 mA. In instances, in which the screw stimulates at values between 11 and 15 mA, screw trajectory exploration is recommended. Screws with thresholds ≤ 10 mA should always be explored, and possibly repositioned or removed. In conjunction with other techniques, EMG threshold testing is a useful and safe modality in determining appropriate C7 pedicle screw placement.

The case for T2 pedicle subtraction osteotomy in the surgical treatment of rigid cervicothoracic deformity.

OBJECTIVE: Rigid cervicothoracic kyphotic deformity (CTKD) remains a difficult pathology to treat, especially in the setting of prior cervical instrumentation and fusion. CTKD may result in chronic neck pain, difficulty maintaining horizontal gaze, and myelopathy. Prior studies have advocated for the use of C7 or T1 pedicle subtraction osteotomies (PSOs). However, these surgeries are fraught with danger and, most significantly, place the C7, C8, and/or T1 nerve roots at risk. METHODS: The authors retrospectively reviewed their experience with performing T2 PSO for the correction of rigid CTKD. Demographics collected included age, sex, details of prior cervical surgery, and coexisting conditions. Perioperative variables included levels decompressed, levels instrumented, estimated blood loss, length of surgery, length of stay, complications from surgery, and length of follow-up. Radiographic measurements included C2-7 sagittal vertical axis (SVA) correction, and changes in the cervicothoracic Cobb angle, lumbar lordosis, and C2-S1 SVA. RESULTS: Four male patients were identified (age range 55-72 years). Three patients had undergone prior posterior cervical laminectomy and instrumented fusion and developed postsurgical kyphosis. All patients underwent T2 PSO: 2 patients received instrumentation at C2-T4, and 2 patients received instrumentation at C2-T5. The median C2-7 SVA correction was 3.85 cm (range 2.9-5.3 cm). The sagittal Cobb angle correction ranged from 27.8° to 37.6°. Notably, there were no neurological complications. CONCLUSIONS: T2 PSO is a powerful correction technique for the treatment of rigid CTKD. Compared with C7 or T1 PSO, there is decreased risk of injury to intrinsic hand muscle innervators, and there is virtually no risk of vertebral artery injury. Laminectomy may also be safer, as there is less (or no) scar tissue from prior surgeries. Correction at this distal level may allow for a greater sagittal correction. The authors are optimistic that these findings will be corroborated in larger cohorts examining this challenging clinical entity.

Complications of Poor Cervical Alignment in Patients Undergoing Posterior Cervicothoracic Laminectomy and Fusion.

OBJECTIVE: This study sought to determine whether a relationship exists between caudal instrumented level and revision rates, neck disability index scores, and cervical alignment in patients undergoing multilevel posterior cervical fusion. METHODS: This study examined a dataset of all patients undergoing posterior cervical decompression and fusion at ≥3 levels, terminating between C4 and T4, between January 2010 and December 2015, with at least 12 months of clinical follow-up. Patients were separated into cohorts based on caudal level of the fusion: C6 (or more cranial), C7, T1, or T2 (or more caudal). Revision rate, neck disability index score, sagittal vertical axis, T1 slope, and cervical lordosis were recorded. Linear regression and multivariate analysis were performed to identify independent predictors of patient outcomes and disparities between ending constructs in the cervical and the thoracic spine. RESULTS: The overall revision rate was 10.8% (n = 24). No statistically significant difference in the revision rate was identified between fusions terminating at C6 or cranial, C7, T1, or T2 and caudal (P = 0.74). Revision correlated strongly with increased sagittal vertical axis (P = 0.002) and T1 slope (P = 0.04). Increased neck disability index score correlated with revision rate (P = 0.01), cervical kyphosis (P < 0.001), and increased sagittal vertical axis (P = 0.04). CONCLUSIONS: This study suggests that constructs terminating in the proximal thoracic spine have similar revision rates, postoperative neck disability index scores, and radiographic measurements as those terminating in the cervical spine. Poor cervical alignment, as evidenced by increased sagittal vertical axis, cervical kyphosis and T1 slope, predicts need for revision and of poorer clinical outcomes.

Uncorrected sagittal plane imbalance predisposes to symptomatic instrumentation failure.

BACKGROUND CONTEXT: Elucidation of the factors responsible for symptomatic failure of spinal instrumentation has been a keen interest for many investigators. PURPOSE: To quantitate the number of symptomatic instrumentation failures (SIFs) encountered during a 2-year period. The effect of sagittal plane imbalance (corrected or uncorrected) on the rate of SIF was evaluated. STUDY DESIGN: Retrospective evaluation of all patients requiring spinal instrumentation to determine which factors predispose toward instrumentation failure. PATIENT SAMPLE: All patients requiring spinal instrumentation over a 2-year period were retrospectively studied. OUTCOME MEASURES: Sagittal plane imbalance pre- and postoperatively was determined using Cobb angle analysis on plain X-rays. SIF was defined as screw back-out and/or breakage, pseudarthrosis, cage migration, or rod disconnection in patients with concordant symptoms. Asymptomatic patients did not demonstrate instrumentation failure on the routine postoperative X-rays. METHODS: Of the 355 patients who fit the criteria, 47 patients presented with either idiopathic or secondary sagittal plane deformity preoperatively. Additionally, long-segment fixation, smoking, age, and fixation across junctional segments were evaluated as risk factors for SIF. RESULTS: Of the 47 patients with sagittal plane deformity, 40 patients (85%) achieved correction demonstrated on postoperative radiographs whereas in 7 (15%), the sagittal plane imbalance was not corrected. Of these seven cases, five suffered instrumentation failure (failure rate 71.5%) versus no instrumentation failures (failure rate 0%) for the remaining 40 patients. SIF was demonstrated in 10 patients overall (failure rate of 2.8%). There was no correlation found between factors such as age, indications for surgery, or long-segment fixation, and instrumentation failure. CONCLUSIONS: Failure to correct sagittal plane deformity intraoperatively predisposes patients to SIF regardless of age, level of surgery, or indication of surgery.

Stress-shielding compared with load-sharing anterior cervical plate fixation: a clinical and radiographic prospective analysis of 50 patients.

OBJECT: In a prospective analysis the authors evaluated the clinical and radiographic outcome of 50 consecutive patients who underwent anterior cervical discectomy and fusion and fixation in which either a stress-shielding or a load-sharing plate (Orion and Premier, respectively) was placed. Data obtained in the two cohorts were analyzed to determine whether clinical or radiographic differences would emerge. METHODS: All patients underwent either one- or two-level fusion in which freeze-dried allogenic tricortical iliac crest bone graft was used. In the first cohort of 25 patients entered into the study, fixation was achieved using a stress-shielding anterior cervical plate (ACP) system, whereas in the second cohort of 25 patients a load-sharing plate system was employed. Patients were evaluated during a follow-up period that ranged from 12 to 35 months. Outcome was determined using a standard questionnaire by which the authors gauged the level of pain, disability, and satisfaction following surgery. The success of surgical fusion and the magnitude of the translation were determined by radiographic evaluation. There was no statistically significant difference between the two cohorts with respect to age, sex, smoking rate, and postoperative complications. With regard to pain and functionality, there was a significant difference (p < 0.05) in favor of the load-sharing system. The fusion rates with the load-sharing and stress-shielding systems were 96 and 92%, respectively, and this difference was not significant. There was no significant difference between the two cohorts with regard to overall satisfaction. The magnitude of vertical translation was significantly greater in the stress-shielding ACP group (p < 0.05) for treatment at one level but not at two. Clinical and radiographic data were available in all patients. CONCLUSIONS: Load-sharing ACP systems exhibited superior clinical results compared with stress-shielding ACPs in this series of patients. The symptomatic pseudarthrosis rate was lower in the load-sharing ACP-treated patients, although this was not statistically significant.