The Effect of Esophageal Temperature Probes on Postoperative Dysphagia Following Primary Anterior Cervical Discectomy and Fusion: A Randomized Prospective Study.

BACKGROUND: The anterior approach to the cervical spine is associated with postoperative dysphagia. It is difficult to predict which patients are most at risk for dysphagia. The objective of this study was to determine if placing an esophageal temperature probe preoperatively would affect the severity and length of postoperative dysphagia. We hypothesize that use of an esophageal temperature probe would result in worse postoperative dysphagia at all measured time points as measured by the Swallowing-Quality of Life (SQAL-QOL) survey after anterior cervical discectomy and fusion (ACDF). METHODS: A total of 44 patients were enrolled in a prospective, randomized controlled trial and randomized into groups: 1 with an esophageal temperature probe placed at the time of surgery and 2 without. A total of 39 patients filled out postoperative SWAL-QOL questionnaires at their preoperatives. Using the survey results, the data were analyzed between groups and subanalyzed based on number of operative levels and sex. RESULTS: SWAL-QOL scores for patients undergoing 2-level ACDF with an esophageal temperature probe were significantly better compared with those without a probe at 2 weeks and 6 months postoperatively. These results were not significant at other time points in in the overall analysis, but a trend toward improved dysphagia scores at each time point postoperatively was seen with the probe group. No differences were found between the 2 groups with respect to age at the time of surgery, sex, and preoperative SWAL-QOL score. CONCLUSIONS: Placement of an esophageal temperature probe at the time of surgery significantly improved postoperative dysphagia scores in patients undergoing 2-level ACDF at 2 weeks and 6 months postoperatively. LEVEL OF EVIDENCE: 2 CLINICAL RELEVANCE: Placement of a temperature probe is a safe and effective technique that is readily available and easily applicable to the practice of spine surgery and may improve postoperative dysphagia after ACDF.

Increased Rates of Septic Shock, Cardiac Arrest, and Mortality Associated With Chronic Steroid Use Following Anterior Cervical Discectomy and Fusion for Cervical Stenosis.

OBJECTIVE: Anterior cervical discectomy and fusion (ACDF) is an established treatment modality for cervical spondylosis. Many patients are on immunosuppressant therapy in the management of various inflammatory spinal pathologies and other comorbid conditions. The impact of chronic steroid use on postoperative complications has not been examined in cervical fusion procedures. The objective of this study was to identify specific postoperative complications associated with steroid/immunosuppressant use following ACDF for cervical stenosis. METHODS: A multi-institutional surgical registry was queried to identify 5377 patients with ACDF diagnosed with cervical stenosis. Patients were stratified into cohorts with a history of steroid/immunosuppressant use for chronic conditions (n = 198, 3.3%) versus those who did not (n = 5179, 96.7%). Propensity-score matching without replacement was implemented to control for preoperative demographics and comorbidities. Pearson χ2 and Fischer exact tests were used in comparing the prevalence of demographics, comorbidities, and complication rates. RESULTS: Upon propensity matching, increased rates of pulmonary embolisms (0.51% vs 0.00%, P = .025), cardiac arrest requiring resuscitation (1.01% vs 0.10%, P = .020), septic shock (0.51% vs 0.00%, P = .025), and mortality (1.52% vs 0.20%, P = .009) in the postoperative 30-day period in patients on chronic steroid/immunosuppressant use were observed. CONCLUSIONS: The results indicate that steroid use/immunosuppression in patients with ACDF has a higher associated rate of pulmonary embolisms, cardiac arrest, septic shock, and mortality. The risk of mortality and these other complications should be carefully considered prior to operative intervention. Future research may investigate steroid-tapering protocols that reduce the rate of infection and other postoperative complications in the subset of immunosuppressed ACDF patients. CLINICAL RELEVANCE: By elucidating the complication rates of ACDF patients on steroids for cervical stenosis, orthopedic surgeons can better stratify patients for risk of postoperative morbidity. Surgeons may have deeper risk-benefit discussions with these specific patients before they elect to have the operation.

Risk Factors for Postoperative Urinary Tract Infections Following Anterior Lumbar Interbody Fusion.

BACKGROUND: Although risk factors contributing to UTI have been studied in posterior approaches to lumbar fusion, there is a lack of literature on factors contributing to UTI in anterior lumbar interbody fusion (ALIF). Our purpose was to identify preoperative independent risk factors for postoperative urinary tract infection (UTI) following anterior lumbar interbody fusion (ALIF) so that surgeons may be able to initiate preventative measures and minimize the risk of UTI-related morbidity following ALIF. METHODS: The American College of Surgeons-National Surgical Quality Improvement Program database was queried to identify 10 232 patients who had undergone ALIF from 2005 to 2016; 144 patients (1.41%) developed a postoperative UTI while 10 088 patients (98.59%) did not. Univariate analyses were conducted to compare the 2 cohorts' demographics and preoperative comorbidities. Multivariate logistic regression models were then utilized to identify significant predictors of postoperative UTI following ALIF while controlling for differences seen in univariate analyses. RESULTS: Age ≥ 60 years (P = .022), female sex (P < .001), alcohol use (P = .014), open wound or wound infections (P = .019), and steroid use (P = .046) were independent risk factors for postoperative UTI. Longer operative times were also independent predictors for developing UTI: 120 minutes ≤ x < 180 minutes (P = .050), 180 minutes ≤ x < 240 minutes (P = .025), and ≥ 240 minutes (P = .001). Postoperative UTI independently increased the risk for pneumonia, blood transfusions, sepsis, thromboembolic events, and extended length of stay as well. CONCLUSIONS: Age ≥ 60 years, female sex, alcohol use, steroid use, and open wound or wound infections independently increased the risk for UTI following ALIF. Future work analyzing the efficacy of tapering alcohol and steroid use preoperatively and reducing procedural time with the aim of lowering UTI risk is warranted. Preoperative wound care is strongly encouraged to decrease UTI risk. LEVEL OF EVIDENCE: III.

A Case Series That Supports the Application of the S2AI Technique for Fractures and Failures After Lumbosacral Fusion.

BACKGROUND: Sacral fractures and failures are uncommon after lumbosacral fusion but have received increasing attention in the surgical literature. They can be difficult to diagnose, making timely treatment difficult. No consensus has been reached on the characteristics of these complications or on optimal treatment. QUESTIONS/PURPOSES: The goal of this retrospective case series is to contribute additional cases of these uncommon complications of lumbosacral fusion to the surgical literature to help clinicians to anticipate, diagnose, characterize, manage, and treat sacral fractures and failures after lumbosacral fusion. METHODS: The medical records of five patients who experienced a sacral fracture or failure after lumbosacral fusion between January 2012 and November 2017 were identified and reviewed retrospectively. Records were reviewed for age, sex, clinical presentation, previous management, outpatient clinical records, imaging, and post-operative course. RESULTS: Four patients in the series experienced a sacral fracture and one experienced hardware failure. All patients presented with elevated pain and underwent revision surgery. Radiographic detection of the fracture or failure occurred at a mean of 11.2 weeks (range, 3 to 24 weeks) after initial surgery, and the mean age of patients was 68.2 years (range, 63 to 80 years). Of the five patients, four were female; two had been diagnosed with osteoporosis and two with osteopenia. In our case series, the S2-alar-iliac (S2AI) technique was used with success in all five cases. CONCLUSION: Fractures and failures after lumbosacral fusion can be difficult to diagnose because of delayed presentation, nonspecific presenting symptoms, and a lack of identifiable mechanism. A high index of suspicion is required to detect these uncommon complications, and patients have responded well to both conservative and surgical treatments.

Characterizing efficiency in the ambulatory surgery setting: An analysis of operating room time and cost savings in orthopaedic surgery.

Changing surgical settings for orthopaedic procedures could drive reductions in operative time and reduce healthcare costs. Time-cost differences were calculated using estimated operating room costs by utilizing the ACS-NSQIP database. Multivariate analyses were generated from propensity-matched cohorts to assess differences between inpatient/outpatient outcomes, and whether surgical length increased risk for complications. Outpatient procedures demonstrated time-cost savings of $1716.06. Generally, inpatient procedures demonstrated increased rates of major/minor complications, reoperation, extended LOS, and unplanned readmission (p < 0.001). Overall, longer operative times increased the risk for postoperative complications (p ≤ 0.001). More elective orthopaedic procedures done on an outpatient basis may result in substantial time-cost savings.

A comparison of narcotic usage and length of post-operative hospital stay in open versus minimally invasive lumbar interbody fusion with percutaneous pedicle screws.

BACKGROUND: Instrumented lumbar fusion can be accomplished through open or minimally invasive techniques. The focus of this study was to compare perioperative narcotic usage and length of hospital stay between patients undergoing open versus minimally invasive spinal surgery (MISS). METHODS: A retrospective chart review was performed on 110 patients who underwent instrumented lumbar fusion over 2 years at our institution. These patients were divided into two groups: those that received open transforaminal interbody fusion (n=69), and those whose surgeries were performed minimally invasively with lateral lumbar transpsoas interbody fusion (LLIF) and percutaneous pedicle screws (n=41). Narcotic usage was recorded for both groups intra-operatively and post-operatively throughout their hospital stay. These values were standardized using an equianalgesia chart. RESULTS: Average narcotic usage post-operatively was significantly lower for the LLIF group relative to those who underwent open lumbar fusion (278.48 vs. 442.06 mg, P=0.03). The average length of post-operative hospital stay was significantly shorter for patients who underwent LLIF compared to those who had an open procedure (4.10 vs. 6.19 days, P=0.02). CONCLUSIONS: Patients who underwent minimally invasive surgery (MIS) LLIF had decreased overall use of opioids in the perioperative period and shorter hospital stays when compared to patients who underwent the open transforaminal interbody fusion approach. These findings support pre-existing literature in favor of LLIF MISS with regards to the above stated outcome measures. The long-term benefits of MISS with regards to narcotic usage in spine patients are not yet known.

Anterior Lumbar Interbody Fusion With Cement Augmentation Without Posterior Fixation to Treat Isthmic Spondylolisthesis in an Osteopenic Patient-A Surgical Technique.

BACKGROUND: Anterior lumbar interbody fusion (ALIF) has been well established as an effective surgical intervention for chronic back pain due to osteoporotic vertebral collapse. Historically, ALIF has consisted of an anterior approach to disc height restoration with a subsequent posterior pedicle screw fixation. Although the applications of cement augmentation with posterior fixation have been previously reported, treatment of patients with both isthmic spondylolisthesis and decreased bone mineral density using a stand-alone ALIF is controversial because of concerns for decreased fusion rates and increased subsidence risk, respectively. We report a case of stand-alone ALIF used to treat a low-grade isthmic spondylolisthesis in the setting of idiopathic thoraco-lumbar scoliosis in a patient with secondary degenerative changes and discuss the benefits of this surgical technique in a patient with several comorbidities. METHODS: An osteopenic 66-year-old woman with multiple medical comorbidities and 2 years of left radicular leg pain was found to have a Myerding grade I isthmic spondylolisthesis in the setting of idiopathic thoraco-lumbar scoliosis with secondary changes. The patient underwent an L5-S1 stand-alone ALIF with anterior cement augmentation without posterior pedicle screw fixation. RESULTS: The patient experienced immediate relief of radicular leg pain postoperatively and had an uneventful course. At 2 years follow-up, she remained symptom free, and radiographs showed excellent fusion and maintenance of intervertebral disc height. CONCLUSIONS: The use of stand-alone ALIF with anterior cement augmentation of the vertebral bodies is a surgical technique that could produce excellent improvement in patients with low-grade isthmic spondylolisthesis in the setting of osteopenia. The use of the all-anterior approach in similar patients with multiple medical comorbidities can also be a useful technique, as it decreases associated morbidity of surgery and complication risks associated with prolonged operative times.

S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up.

STUDY DESIGN: Retrospective review of patients having undergone S2 alar-iliac (S2AI) fixation for long fusions with a minimum two-year follow-up. OBJECTIVES: To report on fusion rates, complications, technique-specific complications of patients having undergone S2AI fixation. SUMMARY OF BACKGROUND DATA: Sacropelvic fixation continues to be a challenge when performing long fusions to the pelvis. S2AI screws have been found to provide solid biomechanical fixation and have been found to have good clinical results in short-term follow-up for pediatric and adult patients. METHODS: Cases were retrospectively reviewed in patients who had placement of S2AI screws for long fusions with at least a two-year follow-up. Demographic data, complications, and reoperations were reviewed. Complications were broken into minor and major categories similar to previous series on pelvic fixation. RESULTS: There were 86 cases identified. Minor and major complications occurred in 29% and 24% of patients, respectively, with the majority of minor complications being intraoperative dural tears. Revision surgery for all causes was performed in 23% of the cohort. Fusion rate at L5-S1 for patients without preoperative pseudarthrosis was 95.3%. Preoperative L5-S1 pseudoarthrosis was identified in 20 patients, 17 (95%) of these went onto fusion after one surgery. There was evidence of S2AI screw lucency in 10.4% of cases. However, the majority of these were asymptomatic. CONCLUSIONS: Sacropelvic fixation using the S2AI technique provides safe, durable fixation with low rates of technique-specific complications and limited need for hardware removal. Complication rates in this series were similar to other series on long fusions to the pelvis. Additionally, fusion rates were high at L5-S1 for both patients with and without preoperative L5-S1 pseudarthrosis. It appears that the S2AI technique is a powerful option for patients with previous L5-S1 pseudarthrosis. LEVEL OF EVIDENCE: Level III.

The unusual presentation of a vascular injury after lumbar microdiscectomy: case report.

Vascular injury during lumbar spine surgery is a relatively rare complication but can have devastating outcomes. The injury may not be apparent during surgery and can present acutely or late in various manners, and some injuries can be asymptomatic. This report discusses the unusual case of a 35-year-old woman who underwent a right L4-5 microdiscectomy for disc herniation and 4 days postoperatively presented with a pulmonary embolus. A subsequent CT scan revealed a pseudoaneurysm and arteriovenous fistula of the right common iliac vein and artery, which gave rise to the embolus. The patient received a right iliac artery stent, and at 4 months after surgery she continues to be symptom free. This report describes the atypical presentation of vascular injury after lumbar microdiscectomy and stresses the importance of cautiously using the pituitary rongeur when removing deeper disc fragments.

Safety and usefulness of free fat grafts after microdiscectomy using an access cannula: a prospective pilot study and literature review.

Placing an interpositional fat graft over the dura has been practiced to prevent sciatica due to nerve tethering from scar. We assessed feasibility, outcomes, and complications of free fat grafts in patients undergoing lumbar microdiscectomy for herniated discs using an access cannula. Retrospective review of prospectively collected data on 69 consecutive patients: those who received autologous fat graft (Group I) and those who did not (Group II). Clinical evaluation of leg pain and nerve tension sign was performed in the immediate postoperative period and at 1 month, 6 months, 12 months, and 24 months. The combined visual analog scale (VAS) scores for leg pain improved from 8.3 preoperatively to 1.3 (P < 0.5). The average VAS score for leg pain was 1.4 (0 to 3) in Group I and 1.3 (0 to 3) in Group II (P > 0.05). Ninety-one percent had resolution of their leg pain immediately postop and 96% at final follow-up. This study found no increased complications with the use of fat graft, but no clinical benefit, therefore the use of fat graft should be discouraged. The potential complication with the use of fat graft is the "mass effect" on the dura, and therefore, the width of the graft should be <1 cm.

Biomechanical evaluation of S2 alar-iliac screws: effect of length and quad-cortical purchase as compared with iliac fixation.

STUDY DESIGN: A biomechanical study conducted on cadaveric specimens. OBJECTIVE: (1) To compare the biomechanical strength of the S2 alar-iliac (S2AI) screw to traditional iliac fixation and (2) to examine the effect of length and trajectory on the S2AI screw. SUMMARY OF BACKGROUND DATA: A recent technique to attain spinal fixation distal to S1 pedicle screws is the S2AI screw using either an open or a percutaneous approach with an altered S2 alar screw trajectory to obtain purchase in the ilium. A novel modification of the S2AI screw is placement with bicortical purchase in the ilium (quad-cortical screw). This may allow for a shorter-length screw with equivalent biomechanics. METHODS: Seven human cadaveric spines (L2-Pelvis) were fixed at L2 proximally and the pubis distally. Pedicle screws were placed from L3-S1 with S2AI screw lengths of 65-mm, 80-mm, or 90-mm iliac screws. S2AI screws were tested with and without quad-cortical purchase. Each specimen was tested on the 6 degrees of freedom spine simulator. A load control protocol with an unconstrained pure moment of 10 Nm was used in flexion-extension, lateral bending, and axial rotation for a total of 3 load/unload cycles. The range of motion was normalized to the intact cadaveric spine (100%). RESULTS: All the instrumented constructs significantly reduced range of motion compared with the intact spine. The L3-S1 construct was statistically significantly less stable than all instrumented constructs in flexion-extension. There was statistically no significant difference between the S2AI screws of all lengths and the iliac screw constructs with offset connectors. CONCLUSION: S2AI screws are biomechanically as stable as the test constructs using iliac screws in all loading modes. Sixty-five-millimeter S2AI screws were biomechanically equivalent to 90-mm iliac screws and 80-mm S2AI screws. Quad-cortical purchase did not statistically significantly improve the biomechanical strength of S2AI screws. LEVEL OF EVIDENCE: N/A.

Deep vein thrombosis and pulmonary embolism after spine surgery: incidence and patient risk factors.

Anticoagulation after spine surgery confers the unique risk of epidural hematoma. We sought to determine the incidence of and patient risk factors for deep vein thrombosis (DVT) and pulmonary embolism (PE) after spine surgery. We retrospectively reviewed the charts of 1485 patients who had spine surgery at a single tertiary-care center between 2002 and 2009. DVT and PE incidence were recorded along with pertinent patient history information. Univariate and multivariate analyses were performed on the data. VTE incidence was 1.1% (DVTs, 0.7%; PEs, 0.4%). Univariate analysis demonstrated that VTEs had 9 positive risk factors: active malignancy, prior DVT or PE, estrogen replacement therapy, discharge to a rehabilitation facility, hypertension, major depressive disorder, renal disease, congestive heart failure, and benign prostatic hyperplasia (P<.05). Multivariate analysis demonstrated 4 independent risk factors: prior DVT or PE, estrogen replacement therapy, discharge to a rehabilitation facility, and major depressive disorder (P>.05). Surgeons with an improved understanding of VTE after spine surgery can balance the risks and benefits of postoperative anticoagulation.

Anatomical feasibility of C-2 pedicle screw fixation: the effect of variable angle interpolation of axial CT scans.

OBJECT: Anatomical variability of the C-2 pedicle poses a challenge for C-2 fixation. The use of multidimensional CT scanning is not widely used but might be an asset to preoperative planning. Careful preoperative planning is imperative for instrumentation at C-2. Fine-cut, noncontrast CT scanning is a useful tool for delineating anatomy; however, the axis of the images is not always along the anatomical axis of the vertebra in question. The authors evaluated the suitability of C-2 pedicles for screw placement by using OsiriX (Pixmeo) software to change the gantry angle of CT angiograms to measure the anatomical dimensions of the C-2 pedicle. METHODS: The authors conducted a retrospective review of CT angiograms of the head and neck from 47 trauma patients seen consecutively at George Washington University Hospital. For each patient, 3 independent observers determined length and width of each C-2 pedicle (94 samples) by using OsiriX. OsiriX is a DICOM viewer that enables navigation and visualization in multidimensional imaging, such as 3D imaging, which was used for this study. Sex-specific measurements were also determined. Vertebral anatomy was studied to determine whether aberrant anatomy would preclude pedicle fixation. Statistical analyses were performed. RESULTS: Of the 47 patients, 27 were male. Overall mean C-2 pedicle widths and lengths were 8.272 ± 1.364 mm and 27.052 ± 3.471 mm, respectively. The average widths and lengths of the pedicle in female patients were 8.040 ± 1.262 mm and 27.241 ± 2.731 mm, respectively, and those in male patients were 8.444 ± 1.414 mm and 26.913 ± 3.933 mm, respectively. The sex difference was statistically significant for width (p = 0.012) but not for length (p = 0.41). On the basis of width, the percentages of pedicles that could tolerate a 3.5-mm and 4.0-mm screw were 98% and 97%, respectively. Vertebral anatomy precluded screw length greater than 14 mm for only 3 patients. CONCLUSIONS: Using multidimensional CT or 3D imaging, the authors found that C-2 pedicles in over 90% of patients could tolerate 3.5-mm and 4.0-mm pedicle screws. Vertebral anatomy precluded use of screw lengths greater than 14 mm for only 3 (6%) of 47 patients. Therefore, the C-2 pedicle might be more tolerant of fixation than previously reported.

Instrumented reduction of a fixed C1-2 subluxation using occipital and C2/C3 fixation: A case report.

BACKGROUND: Different strategies exist for reduction of the cervical spine. Placement of C1 lateral mass screws is a powerful technique but may be impossible in a degenerative or revision setting. We report the open, posterior-only, and instrumented reduction of a fixed C1-2 subluxation using occipital and C2/C3 fixation. The patient had rheumatoid arthritis and had undergone previous surgery of the cervical spine. METHODS: We performed a retrospective chart review and focused appraisal of the literature. RESULTS: Satisfactory reduction was achieved with this infrequently reported technique. CONCLUSIONS/LEVEL OF EVIDENCE: Spine surgeons may consider the described procedure a viable treatment alternative in problematic subluxations of the cervical spine. Level V.

Less exposure surgery for multilevel anterior cervical fusion using 2 transverse incisions.

Multilevel anterior cervical fusion often necessitates a large extensile incision for exposure and substantial retraction of the esophagus for placing long plates, potentially predisposing patients to complications such as dysphagia, dysphonia, and neurovascular injury. To the authors' knowledge, the use of 2 incisions as an option has not been published, and so it is not intuitive to young surgeons or widely practiced. In this report, the authors discuss the advantages and raise awareness of using 2 incisions for multilevel anterior cervical fusion, and they document a safe skin bridge length. They also describe the advantages of using 2 incisions for performing multilevel anterior cervical fusion either at contiguous or noncontiguous levels as in adjacent-segment disease. By using the 2-incision technique, the authors made the surgery technically easier and diminished the amount of esophageal retraction otherwise needed through 1 long transverse or longitudinal incision. A skin bridge of 3 cm was safe.

Traumatic C4-C5 unilateral facet dislocation with posterior disc herniation above a prior anterior fusion.

We report the case of a unilateral cervical facet dislocation above the level of a prior non-instrumented cervical discectomy and fusion, resulting in incomplete neurologic injury. Pre-reduction imaging demonstrated a large posterior disk extrusion. This finding altered our management approach from closed reduction to urgent anterior cervical discectomy, open anterior reduction, and fusion. The patient had excellent neurologic recovery and outcome at 12 months postoperative follow-up.

Anatomical parameters of subaxial percutaneous transfacet screw fixation based on the analysis of 50 computed tomography scans: Clinical article.

OBJECT: Cervical transfacet screw placement has been described in the literature. Although the technique shows promise for percutaneous application, parameters for screw placement have not been well delineated. This study used reconstructed CT scans with imaging software to assess the feasibility of percutaneous transfacet screw placement, analyzing potential entry angles, transfacet lengths, and sex differences at each subaxial level. METHODS: Fifty consecutive cervical CT scans (obtained in 26 males and 24 females [mean age 41.5 years]) were reformatted using OsiriX software, and transfacet lengths, entry angles, and potential occipital clearance were analyzed at all subaxial levels. Statistical analyses were used to determine the differences, if any, between transfacet lengths, entry angle, and occipital clearance across individual cervical levels. Repeatability was quantified by calculating the intraclass correlation coefficient and Cohen kappa value. RESULTS: A total of 200 transfacet lengths and 200 entry angles in 50 patients were analyzed. The mean transfacet lengths were 17.9 ± 2.6, 17.6 ± 3.2, 16.3 ± 3.6, and 13.1 ± 2.2 mm at C3-4, C4-5, C5-6, and C6-7, respectively, with mean entry angles at 52.7° ± 7.8°, 56.5° ± 8.0°, 55.0° ± 8.8°, and 53.0° ± 8.7°, respectively. Analysis of variance revealed a significant difference between the mean transfacet lengths, while post hoc analysis revealed significantly larger transfacet lengths in the upper 2 cervical levels (C3-4 and C4-5) than in the lower 2 cervical levels (C5-6 and C6-7). Analysis of variance demonstrated no significant difference between the entry angles. Males had significantly larger transfacet lengths at C5-6 (17.4 vs 15.1 mm) and C6-7 (13.7 vs 12.4 mm) than females. The occiput would have blocked percutaneous screw placement in 86%, 78%, 54%, and 20% of the cases at C3-4, C4-5, C5-6, and C6-7, respectively. Transfacet lengths may accommodate longer screws in the upper cervical spine, but potential screw sizes decrease in the lower subaxial levels. A transfacet entry angle of approximately 50° or greater was associated with a higher incidence of occipital clearance. Additionally, the occiput may pose a significant obstruction to percutaneous transfacet fixation in upper subaxial levels. Interrater reliability was poor for screw angle and length measurements, but was satisfactory in intrarater analysis in 6 of 8 measurements. There was moderate to good agreement of occipital clearance in all but one measurement. CONCLUSIONS: Cervical transfacet screw placement is possible from C-3 to C-7. Because occipital clearance can be difficult at C3-4 and C6-7, the use of curved or flexible instruments may be necessary to obtain the appropriate screw trajectory. Screw lengths varied with spinal level and the sex of the patient.

Change in sagittal balance with placement of an interspinous spacer.

STUDY DESIGN: A prospective case series. OBJECTIVE: To determine the effect of X-STOP implantation on sagittal spinal balance using 36-inch films. SUMMARY OF BACKGROUND DATA: Interspinous process spacers have been shown as an effective treatment of neurogenic claudication. The devices block the last few degrees of extension at the stenotic level, thus preventing compression of the nerve roots. These devices have been criticized because they may push the patient's spine into a kyphotic position. However, opening the stenotic level may allow a patient to stand more upright, thereby improving sagittal balance. METHODS: Institutional review board's approval was obtained. A prospective study of 20 patients who were undergoing an X-STOP insertion was utilized. Their spines were x-rayed preoperatively and postoperatively with 36-inch films. Preoperative and postoperative sagittal balance was measured with a C7 body plum line on both films and the difference was measured. Lumbar lordosis was also compared using Cobb angles. RESULTS: Measurements taken from lateral full-length spine radio-graphs showed an average improvement in sagittal balance of 2.0 cm (range -3.7 to 6.1 cm). The average change in lordosis was -1.1°. CONCLUSION: Although previous studies of interspinous process distraction have examined segmental lordosis, disc angles, and other parameters, this study is the first to examine overall spinal balance on full-length films. Interspinous distraction does not seem to be detrimental to sagittal balance, and may improve it.

Biomechanical comparison of transpedicular versus intralaminar C2 fixation in C2-C6 subaxial constructs.

STUDY DESIGN: Biomechanical study. OBJECTIVE: To compare the relative rigidity of C2 transpedicular versus intralaminar fixation with and without offset connectors in C2-C6 subaxial constructs. SUMMARY OF BACKGROUND DATA: Insufficient biomechanical data exists on C2 laminar fixation in subaxial constructs, and no study has considered C2-C6 subaxial constructs or the use of offset connectors. METHODS: Six fresh-frozen cadaveric cervical spines underwent rigidity testing in the intact condition and after a destabilizing C3-C6 laminectomy. Specimens were instrumented with 20 mm pedicle and 20 mm intralaminar screws at C2, and with 14 mm lateral mass screws from C3-C6. In random order, three conditions (C2 pedicle screws, C2 laminar screws, and C2 laminar screws with offset connectors) were tested in flexion-extension, axial rotation, and lateral bending. RESULTS: Laminar screws in C2-C6 constructs were equivalent to transpedicular fixation in flexion-extension (P = 0.985), were significantly more rigid than pedicle screws in axial rotation (P = 0.002), and were significantly less rigid than pedicle screws in lateral bending (P = 0.002). Laminar screw constructs were more rigid than the intact condition in all planes.

Occipitocervical junction: imaging, pathology, instrumentation.

The occipitocervical junction (OCJ) is a highly specialized area of the spine. Understanding the unique anatomy, imaging, and craniometry of this area is paramount in recognizing and managing the potentially devastating effects that pathology has on it. Instrumentation techniques continue to evolve, the goal being to safely obtain durable, rigid constructs that allow immediate stability, anatomical alignment, and osseous fusion. This article reviews the pathologic conditions at the OCJ and the current instrumentation and fusion options available for treatment. The general orthopedist needs to recognize the pathology common in this region and appropriately refer patients for treatment.