Journal of spine surgery最新文献

Background: Interspinous devices were introduced in the field of spine surgery as an alternative to traditional pedicle screw fixation in selected patients for treatment of spinal stenosis and fixation. These devices designs have evolved from non-fixated extension blocks to sophisticated interspinous fixation devices (IFDs). There is an absence of literature comparing the biomechanical fixation strength of different IFD plate designs and the role of set screw locking systems. The aim of this study was to evaluate fixation strengths by bench testing static disassembly and pullout strength of two dissimilar IFD designs and locking mechanisms. We hypothesized that the InSpan (InSpan LLC, Burlington, MA, USA) dual-locking symmetrically IFD plate designed will have stronger fixation than the Aspen (ZimVie, Parsippany, NJ, USA) single-locking asymmetric IFD plate design.

Methods: We conducted two biomechanical bench tests to evaluate the load to failure locking characteristics of symmetrical InSpan and asymmetrical Aspen IFD designs. Static pullout testing involved locking each IFD to the stainless steel and 40 pcf cellular polyurethane foam and measuring pullout load and displacement six times. Seven InSpan and two Aspen IFDs (including the "used" IFDs from the pullout testing) underwent static disassembly tests using a pair of disassembly fixtures positioned between the IFD plates to measure disassembly force and displacement. All tests were performed under ambient conditions using an INSTRON 8874 Bi-Axial Tabletop Servohydraulic Dynamic Testing System (INSTRON, Norwood, MA, USA), and data was collected at a 0.2 mm/s displacement control rate until the test was stopped when there was a drop in the continuously increasing force against resistance (gross failure).

Results: The InSpan IFD experienced 94.81% higher resistance to pullout compared to the Aspen IFD in static pullout testing (P<0.05), owing to its notably larger footprint area of 69.8%. Gross failure for both IFD implant designs occurred at the foam block-block interface. In static disassembly testing, pristine InSpan required 60.7% higher force over pristine Aspen and 401.3% for "used" IFDs. Gross failure was characterized by the gradual distraction of the plates and material removal at the set screw contact points. Implant failure at the block-implant interface emphasized the pivotal role of teeth design and the contact surface area of the plates in ensuring stability.

Conclusions: The dual-locking symmetrical InSpan IFD outperformed single-locking asymmetric Aspen IFD in both static disassembly and pullout bench tests. This highlights the benefits of InSpan's improved design and its potential for enhanced long-term stability in spinal fixation applications.

Instrumentation of the upper cervical spine, such as cervical pedicle, lateral mass, pars, or translaminar screws, is considered high risk due to the specific challenges of this anatomic region, including the proximity of vertebral and carotid arteries and nerve roots, as well as its delicate bony architecture. In recent years, advanced three-dimensional (3D) imaging techniques, such as intraoperative computed tomography (iCT; AIRO CT), have emerged, enabling computer-assisted navigation (CAN). This integration of real-time imaging into navigation enhances screw accuracy and diminishes perioperative risks, extending to the postsurgical confirmation of screw placement. Although CAN utilization has become more prominent in lumbar and thoracic surgeries, its integration into cervical spine procedures has been constrained thus far. This can be ascribed to the variable screw trajectories necessary for cervical spine procedures, coupled with potential anatomical variations such as a high-riding vertebral artery, increasing the degree of challenge during surgery. To date, no study has comprehensively described in detail the technique of upper cervical instrumentation employing automatic image registration, navigation, and iCT validation of the positioned screws. In this manuscript, a detailed description of CAN in high cervical instrumentation is given, including C1 lateral mass screws with the notching technique, C2 and C3 pars screws, and translaminar screws guided by preoperative magnetic resonance imaging (MRI) data and iCT for assessment of screw position. For this purpose, three different patients suffering from distinct cervical pathologies, such as nonunion of a C2 fracture and atlantoaxial arthropathy with or without ankylosis, are presented, with a specific surgical approach tailored to the anatomical variations of each patient.

Background: Yolk sac tumor (YST), or endodermal sinus tumor, is classically associated with pediatric populations. Metastasis to the spine rarely occurs, usually involving the lower thoracic or lumbar vertebrae. The objective of this report is to present a rare case of YST metastasis to the lower cervical and upper thoracic vertebrae in an adult male. A case-based review of the literature on metastatic YSTs was also performed as an update to the relevant literature.

Case description: A 28-year-old male with a history of YST presented to our institution with urinary retention, increasing weakness in the upper extremities, and acute onset lower extremity weakness. Computed tomography (CT) and magnetic resonance imaging (MRI) scans confirmed evidence of metastasis from a known YST with symptomatic cord compression. The patient was treated with surgical excision via decompressive laminectomies with instrumentation as described, and histopathologic analysis of the specimen confirmed YST metastasis. His disease recurred one year after index surgery. He succumbed to his disease despite repeated debulking.

Conclusions: Metastasis of YST is rare, but metastasis to lower cervical and upper thoracic vertebrae is possible. YSTs are usually treated via primary surgical resection. Systemic chemotherapy and radiation may prevent recurrence. However, individualized treatment is imperative for improved patient outcomes.

Background: Three column osteotomies (3CO) are a powerful tool for the correction of rigid sagittal spinal deformities. However, 3CO surgeries are technically demanding procedures that are associated with prolonged operative times, large amounts of intraoperative blood loss, and high rates of post-operative neurological and medical complications. The purpose of this retrospective cross-sectional study is to delineate the effects of blood loss, blood transfusion, and tranexamic acid use on perioperative outcomes following 3CO.

Methods: Patients undergoing 3CO between 2014 and 2021 were identified using current procedural terminology (CPT) codes, and charts were reviewed for demographics, surgical characteristics, and post-operative length of stay (LOS). Statistical analysis included T-tests for continuous characteristics and χ² testing for categorical characteristics. Regression models were used to further investigate relationships between outcomes and variables of interest.

Results: Forty-two patients met inclusion criteria. Increased intensive care unit (ICU) LOS was positively correlated with increased operative length (P=0.02), percent estimated blood volume (EBV) lost (P=0.02), and number of units of red blood cell transfusion (P<0.001). Increased hospital LOS was associated with increased number of intraoperative blood transfusions (P=0.01). Linear regression analyses controlling for age, gender, and American Society of Anesthesiologists (ASA) class showed that each 21% increase in EBV loss was associated with a one day increase in ICU LOS (P=0.01). Similarly, each additional unit of packed red blood cells transfused was associated with 0.728 day increase in hospital LOS.

Conclusions: Increased intraoperative blood loss was associated with longer ICU stays. Red blood cell transfusions were also associated with increased hospital and ICU LOS. No variables of interest related to intraoperative blood loss or blood transfusion were associated with readmission or reoperation at any time point. These findings highlight the need for continued focus on surgical techniques and adjuncts that can minimize blood loss and transfusion requirements.

Background: Odontoid process fractures, particularly type 2 fractures, pose significant treatment challenges due to their high rates of nonunion. Anterior odontoid screw fixation (AOSF) is traditionally performed using percutaneous methods with biplanar fluoroscopy. Computer-assisted navigation has emerged as a promising tool to enhance surgical precision, but its application in AOSF is rarely utilized. Cervical spine stability during AOSF is crucial for optimal outcomes and navigational accuracy.

Case description: A 64-year-old male presents with a displaced type 2 odontoid fracture following a fall. The fracture was treated with AOSF with the assistance of computed tomography (CT) navigation. A practical positioning technique employing a pressure infusion bag was introduced to stabilize cervical motion during surgery. This technique allows for precise instrumentation while minimizing the risk of navigational inaccuracy. Intraoperative imaging confirmed excellent fracture reduction and screw placement, facilitating a favorable surgical outcome.

Conclusions: CT navigation for AOSF is not yet widely adopted for the treatment of type 2 odontoid fractures due to inherent risks of fracture displacement, navigational inaccuracy, and iatrogenic injury. The off-label use of a pressure infusion bag for cervical stabilization offers a practical and cost-effective solution to enhance surgical precision. While further research is needed to compare the efficacy and radiation exposure of navigation-guided versus fluoroscopy-assisted AOSF, our report demonstrates that a safe and optimal outcome can be achieved using navigation-guided techniques.

Background: Cervical laminectomy may be underutilized in the treatment of cervical spondylotic myelopathy (CSM) due to concerns regarding potential for post-operative instability and/or kyphosis. The purpose of this retrospective, observational study is to assess the short-term clinical and radiological outcomes as well as complications associated with a group of carefully selected patients who underwent laminectomy alone for CSM and compared them to a cohort of patients who underwent laminectomy with fusion.

Methods: Patients with CSM were identified via review of a single surgeon's cases. All patients underwent preoperative clinical evaluation, lateral flexion-extension cervical radiographs, and documentation of neck and/or extremity pain via Nurick Scale and modified Japanese Orthopedic Association (JOA) scores. Postoperative follow-up occurred at 1, 3 and 6 months for all patients. Statistical analysis was performed via Student's t-test for parametric values and Wilcoxon (Mann-Whitney) rank sum test for ordinal scores. Multi-variable linear regression was used to correct for co-variance.

Results: Forty-one patients who underwent laminectomy alone and 13 patients who underwent laminectomy with fusion were identified who met inclusion criteria. Both groups demonstrated significant improvement on Nurick and JOA scores postoperatively. Two patients in the laminectomy alone group required a subsequent one-level anterior cervical discectomy and fusion for onset of postoperative neck pain, without neurological symptoms or new deficits in the follow up period. There was no difference in rates of post-operative kyphosis between the groups.

Conclusions: In appropriately selected patients without pre-operative kyphosis or abnormal motion on flexion-extension films, cervical laminectomy remains a safe and effective treatment option.

Background: Achieving optimal immediate stability is crucial in lumbar fusion surgeries. Traditionally, four pedicle screws have been utilized to provide posterior stability at the L5-S1 level. However, the use of bilateral transfacet pedicle screws (TFPS) as an alternative construct has shown promising results in terms of biomechanical stability. This research paper investigates the biomechanical stability of TFPS with a lag design in comparison to equivalent-sized unilateral or bilateral fully threaded pedicle screw-rod (PSR) constructs at the L5-S1 disc level. The study assesses the immediate stability achieved by these constructs which have clinical implications in achieving lumbar segment fusion. We hypothesized that bilateral TFPS will yield immediate lumbar fixation that is comparable to unilateral or bilateral PSR constructs.

Methods: Cadaveric biomechanical testing was conducted in vitro to evaluate the stability of posterior fixation using bilateral TFPS (FacetFuse^®, LESSpine, Burlington, MA, USA), bilateral and unilateral PSR (PedFuse Return, LESSpine, Burlington, MA, USA) constructs measuring 5.0 mm × 40 mm. A comprehensive analysis of range of motion (ROM) and stability under various loading conditions was performed to a maximum of 7.5 Nm. The constructs were assessed for their ability to provide immediate stability at the L5-S1 disc level.

Results: Fourteen specimens were analyzed with an average age of 53.14±10.99 years and comparable bone mineral density. TFPS demonstrated a reduced ROM that was notably lower than that of unilateral PSR in all loading modes and was comparable to bilateral PSR, especially in extension and axial rotation (AR). The unilateral and bilateral PSR groups differed notably in lateral bending (LB) and AR.

Conclusions: Bilateral TFPS demonstrated superior immediate stability than unilateral PSR and was an equivalent substitute to bilateral PSR constructs at the L5-S1 disc level. Further clinical investigations are necessary to validate these results and ascertain the long-term outcomes and advantages associated with the use of bilateral TFPS as an alternative construct. Our findings showed that bilateral TFPS could potentially reduce the number of required pedicle screws while achieving comparable stability in lumbar fusion procedures.

Background: Management of multiple myeloma (MM) of the spine includes a multimodal approach consisting of chemotherapy, bisphosphonates, radiation, and surgical intervention. This study aims to explore the trends in surgical treatment of MM including hospital costs, odds of complications, and the impact of patient comorbidities on the risk of complications using the National Inpatient Sample (NIS) database.

Methods: The NIS was queried for patients with MM and plasmacytoma of the spine who underwent surgical intervention between 2005 and 2014. Rates of spinal decompression, spinal stabilization with or without decompression, and vertebral augmentation were analyzed. The effect of various patient characteristics on outcome was analyzed by multivariate analysis and stratified by surgical procedure.

Results: Vertebral augmentation (9,643, 65.7%) was the most commonly performed procedure, followed by spinal stabilization with or without decompression (4,176, 28.4%) and then decompression alone (868, 5.9%). The total population-adjusted rate of surgical management for MM remained stable during the study period, while the rate of spinal stabilization increased (P<0.001) and the rate of vertebral augmentation decreased (P=0.01). Vertebral augmentation was associated with shorter inpatient hospital stay, lower total cost, and higher likelihood of discharging to home. The complication rate increased over time for vertebral augmentation procedures (P<0.001) while spinal stabilization and decompression complication rates remained stable. The complication rate for all procedures was higher in male patients (P<0.001) and increased with the number of patient comorbidities (P<0.001).

Conclusions: Spinal surgery seems to be increasing for the management of spinal MM in the inpatient setting, while the rate of vertebral augmentation is decreasing. Vertebroplasty and similar palliative procedures may continue to decrease as advancements in surgical technology and technique allow for safer surgical intervention. The decision to employ aggressive surgical intervention, however, must always take into account the patient's comorbidities, overall systemic disease burden, and the potential for significant enhancement in meaningful clinical outcome.

Background: Anterior retroperitoneal lumbar spinal exposure has traditionally been performed in the supine position (SUP) to access the L4-L5 and L5-S1 disc spaces where lateral approaches may be unsafe. However, advancements in lateral single position surgery have resulted in advocacy for anterior L4-5 disc access in the lateral decubitus position (LAT). While L5-S1 access in the lateral position is well-described, no series of L4-5 anterior access in the lateral position has been published. The study aims to evaluate the safety of anterior lumbar exposure at the L4-5 disc level in the LAT compared to the SUP.

Methods: A multi-center retrospective study of patients who underwent anterior retroperitoneal lumbar exposure involving the L4-5 disc level were classified according to patient positioning: (I) LAT or (II) SUP.

Results: One hundred and forty patients were included, of which 65 LAT and 75 SUP patients. Two hundred and thirty-eight anterior levels were exposed, including 113 levels performed in lateral and 125 levels in supine. Mean anterior levels fused was similar (1.74 vs. 1.67 levels, P=0.37). Significantly more LAT patients underwent additional lateral lumbar interbody fusion (LLIF) (21.50% vs. 0.00%, P<0.001). A larger proportion of LAT patients underwent surgery for spinal deformity (21.50% vs. 6.70%, P=0.01) and planned staged procedures (21.50% vs. 6.70%, P=0.01). Intraoperative complication rates were similar (3.10% vs. 4.00%, P=0.77), including similar vascular injury rates (1.50% vs. 0.00%, P=0.28) and no visceral injury. Postoperative complications (15.40% vs. 38.70%, P=0.002) were significantly lower in the LAT group, however major complications (6.20% vs. 13.30%, P=0.16) were similar between groups. Fewer LAT patients experienced postoperative ileus (0.00% vs. 6.70%, P=0.03). The rate of reoperation within 30 days (3.10% vs. 6.70%, P=0.33) and 90 days (3.10% vs. 10.70%, P=0.09) were similar between groups.

Conclusions: Anterior lumbar spinal exposure of the L4-5 disc in the LAT is safe compared to supine exposure, despite higher case complexity in the lateral position.