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.

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.

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.

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.

The anatomic suitability of the C2 vertebra for intralaminar and pedicular fixation: a computed tomography study.

BACKGROUND CONTEXT: Several methods have been used to stabilize the atlantoaxial joint, including the use of C2 pedicle and laminar screws. No report has used computed tomography (CT) angiograms to compare the risk to the vertebral artery or assess the suitability for each fixation technique. PURPOSE: To compare the suitability of C2 pedicle versus laminar screws using CT angiograms. STUDY DESIGN: We retrospectively evaluated the anatomic dimensions of the C2 lamina and pedicle in 50 patients using CT angiograms. METHODS: We retrospectively reviewed the last 50 patients admitted who underwent CT angiograms of the head and neck. Data recorded included the pedicle length and width and the laminar length and width. Vertebral artery anatomy was also assessed to determine if an aberrant location would preclude pedicle fixation. RESULTS: Mean pedicle length and width were 15.5±3.5 and 4.7±1.7 mm, respectively, with 24% of patients having anatomy that would preclude 3.5-mm pedicle screw fixation. The mean lamina length and width were 25.2±3.6 and 5.5±1.4 mm, and more than 90% of patients could tolerate a 3.5-mm C2 laminar screw. CONCLUSION: Preoperative CT angiography or noncontrast CT is an excellent method to delineate the anatomy at C2 to determine the suitability for pedicle or intralaminar fixation. In cases where vertebral artery anatomy precludes C2 pedicle fixation, more than 90% of patients may be a candidate for C2 intralaminar fixation.

An S-2 alar iliac pelvic fixation. Technical note.

Multiple techniques of pelvic fixation exist. Distal fixation to the pelvis is crucial for spinal deformity surgery. Fixation techniques such as transiliac bars, iliac bolts, and iliosacral screws are commonly used, but these techniques may require separate incisions for placement, leading to potential wound complications and increased dissection. Additionally, the use of transverse connector bars is almost always necessary with these techniques, as their placement is not in line with the S-1 pedicle screw and cephalad instrumentation. The S-2 alar iliac pelvic fixation is a newer technique that has been developed to address some of these issues. It is an in-line technique that can be placed during an open procedure or percutaneously.

Feasibility of minimally invasive sacropelvic fixation: percutaneous S2 alar iliac fixation.

STUDY DESIGN: A cadaveric study with postoperative computed tomography scan to evaluate instrumentation placement. OBJECTIVE: To successfully place percutaneous sacropelvic instrumentation. SUMMARY OF BACKGROUND DATA: S2 iliac fixation has been in use clinically at some centers. Recently, anatomic data have been presented on the technique. The purpose of this study is to determine the feasibility of percutaneous placement of S2 iliac sacropelvic fixation (1) without damage to vital structures and (2) with in-line placement with S1 pedicle screws. METHODS: Eight cadaveric spines were used in this study. Percutaneous pedicle screws were placed from L3-S1 in 4 and from L2-S1 in the remainder. Percutaneous S2 iliac screws were placed using a modification of the open technique. Rods were placed using minimally invasive techniques. All specimens were CT scanned. Trajectory of the screws was measured from CT scans. Maximal length was judged by a k-wire left in the S2 iliac screw. CT scans were critically evaluated for risks to visceral and neurovascular structures as well as cortical breaches. RESULTS: Average length of the screws was 92.5 mm (range, 69-120 mm). No screw was intrapelvic or risked any visceral or neurovascular structure. No screws violated the cortex of the ilium. All S2 iliac screws were in-line with the S1 pedicle screws. The average cephalocaudad trajectory was 29 degrees caudal from direct lateral. The average anterior-posterior angulation was 42 degrees from a horizontal line connecting the PSIS. CONCLUSION: Use of the S2 iliac technique may be a viable option in minimally invasive thoracolumbar deformity surgery. The screws were all in-line and connected easily to the cephalad instrumentation. On average, a length of approximately 90 mm was attained. No visceral or neurovascular structure was injured. Visualization of the first dorsal foramen and a standard anteroposterior and inlet radiograph were used for placement.

Pseudarthrosis of the spine.

Pseudarthrosis is the result of failed attempted spinal fusion. This condition typically manifests with axial or radicular pain months to years after the index operation. Diagnosis is based on clinical presentation and imaging studies, after other causes of persistent pain are ruled out. The degree of motion seen on flexion-extension radiographs that is indicative of solid or failed fusion remains a point of controversy. Thin-cut CT scans may be more reliable than radiographs in demonstrating fusion. Metabolic factors, patient factors, use and choice of instrumentation, fusion material, and surgical technique have all been shown to influence the rate of successful fusion. Treatment of the patient with symptomatic pseudarthrosis involves a second attempt at fusion and may require an approach different from that of the index surgery as well as the use of additional instrumentation, bone graft, and osteobiologic agents.

An anatomic study of the S2 iliac technique for lumbopelvic screw placement.

STUDY DESIGN: An anatomic study conducted on cadaveric specimens. OBJECTIVES: The objectives of the study were (1) to determine course of S2 lumbopelvic screws with reference to the articular cartilage of the sacroiliac joint, (2) to determine the length and trajectory of screws placed using anatomic placement techniques, and (3) to determine vital structures at risk using this technique. SUMMARY OF BACKGROUND DATA: Multiple techniques exist for fixation distal to S1 including alar screws, iliac post bolts, and transiliac rods. Distal fixation is crucial in adult deformity surgery when fusion to the sacrum is indicated. METHODS: Five female and 5 male cadaveric specimens were instrumented with S1 promontory screws and S2 iliac lumbopelvic screws. The specimens then underwent computed tomography scanning to determine structures at risk, cortical violations, and characteristics of screws placed. The sacroiliac joints were opened to examine articular cartilage penetration. RESULTS: Articular violation occurred in 60% of screws placed. Average length was 84 mm. No vital structures were at risk from screw placement. No intrapelvic cortical violations occurred. CONCLUSION: S2 iliac technique is a potential option for distal fixation in spine surgery. Biomechanical and clinical data are required to fully evaluate the potential of this technique.

Perioperative complications of threaded cylindrical lumbar interbody fusion devices: anterior versus posterior approach.

Few data are available to evaluate approach-related differences in perioperative complications with lumbar interbody fusion devices. Complications occurring in the intraoperative and immediate postoperative period were identified and categorized for 31 consecutive posterior lumbar interbody fusions (PLIFs) and 88 consecutive anterior lumbar interbody fusions (ALIFs). In this study, all lumbar interbody fusions were conducted with threaded cylindrical devices as stand-alone internal fixation devices. Multivariate analysis was used to account for potential covariates and identify factors associated with an increased complication risk. Twenty-two percent of the patients had a perioperative complication. The relative risk of having a perioperative complication was 4.75 times higher for the PLIF group. All intraoperative complications occurred in the PLIF group. The relative risk of having a major postoperative complication was 6.8 times higher in the PLIF group than the ALIF group. Anterior approached patients tended to have visceral (ileus, 6%) and vascular (deep venous thrombosis, 2%) complications. In the posterior group, complications were neurologic and dura related (pseudomeningocele, 16%; epidural hematoma, 3%) and occurred most frequently in patients that had had previous posterior lumbar surgery (31% with major complication).

Autogenous tibial strut grafts used in anterior spinal fusion for severe kyphosis and kyphoscoliosis.

STUDY DESIGN: A retrospective review was performed. OBJECTIVE: To evaluate the results of autogenous tibial strut grafts for anterior fusions in children with severe kyphosis and kyphoscoliosis regarding maintenance of correction, clinical outcome, graft fractures, and donor-site morbidity. SUMMARY AND BACKGROUND DATA: Anterior strut grafts harvested from the iliac crest, rib, and fibula often are used to treat severe kyphosis and kyphoscoliosis. Several studies in the literature have observed graft failures, loss of correction, or donor-site morbidity when these grafts have been used. Autogenous tibial strut grafts provide some theoretical advantages with minimal donor-site morbidity. METHODS: This review included 15 patients with severe kyphosis/kyphoscoliosis who underwent anterior spinal fusion with autogenous tibial strut grafts. Among these patients, 13 underwent staged or simultaneous posterior fusions, and 4 underwent cord decompression for myelopathy. An average of seven levels (range, 3-13) were fused anteriorly. Preoperative, postoperative, and latest follow-up radiographs were evaluated for graft incorporation, fracture, hardware failure, and spinal alignment. Patients were examined at the latest follow-up visit, and charts were reviewed to assess neurologic status, back pain, alignment, complications, and donor-site problems. RESULTS: All the patients were available for clinical examination. The mean follow-up period was 3.9 years (range, 2-8 years). The mean kyphosis measured 89 degrees before surgery, 62 degrees after surgery, and 66 degrees at the most recent follow-up assessment. In patients with kyphoscoliosis, the mean coronal curve measured 64 degrees before surgery, 42 degrees after surgery, and 46 degrees at the latest follow-up assessment. Apparent fusion was observed in all cases with no graft fractures. One patient reported mild donor-site discomfort. CONCLUSIONS: Autogenous tibial strut grafts provide physical advantages over commonly used iliac crest, rib, and fibula grafts. The tibia provides dense cortical bone with ample length and mechanical strength, although the actual strength of each strut was not measured directly. In this study, adequate correction was maintained throughout an average follow-up period of 3.9 years, and solid fusion was obtained in all cases. The results indicate that this technique offers a reliable means of providing anterior support in the management of severe kyphosis with virtually no donor-site morbidity. Although the number of patients in this review was limited, the authors believe that anterior autogenous tibial struts are an excellent alternative for the treatment of severe kyphosis and kyphoscoliosis.