International Journal of Spine Surgery最新文献

Background: During lumbar total joint replacement (LTJR), component misalignment during implantation may affect the bearing surface interaction. In this study, validated computational models of the lumbar spine were used to investigate a range of clinically relevant misalignment scenarios.

Methods: A finite element model (FEM) of the LTJR, exposed to mode I (normal wear) and mode IV (impingement) wear boundary conditions, was previously validated following the ASME V&V 40 standard. The LTJR FEM was virtually implanted into a previously validated FEM of the lumbar spine (L3-L5) at L4 to L5. The model included vertebrae, major spinal ligaments, erector muscle forces, and intervertebral discs. Misalignment was introduced by adjusting the bilateral implant axial plane convergence angle (20°-40°), anterior-posterior offset (0-4 mm), and coronal plane tilt (±20°). Analyses were conducted using LS-DYNA3D (ANSYS) under boundary conditions simulating bending at the waist. Contact pressures and von Mises stresses were evaluated for each misalignment scenario and compared with those developed during mode I and mode IV impingement scenarios.

Results: Axial plane convergence angle had minimal impact on contact stress and von Mises stress magnitude and distribution. Increasing anterior-posterior offset led to higher stresses on the anteriorly shifted component but did not significantly alter the overall stress pattern. Coronal tilt had the most substantial effect on both stress magnitude and distribution.

Conclusion: Overall, polyethylene stresses in all misalignment scenarios remained below mode IV impingement levels. Contact areas remained within the intended spherical bearing surfaces without signs of impingement. LTJR contact stresses were found to be reasonably insensitive to misalignment under boundary conditions representing bending at the waist.

Clinical relevance: This work assesses the impact of clinically relevant implant misalignment scenarios on the polyethylene stresses associated with damage and wear for a novel LTJR and offers best practice guidelines for surgeons.

Level of evidence: 5:

Background: Adult isthmic spondylolisthesis often remains stable in adulthood, but progressive neural compression can occur due to scar tissue, bony overgrowth, and disc degeneration. Conventional endoscopic techniques such as the interlaminar or transforaminal approaches may be limited by anatomical constraints in adult isthmic spondylolisthesis, making complete decompression difficult.

Methods: A 70-year-old man presented with bilateral leg pain and neurogenic claudication. Imaging revealed bilateral L4 to L5 lateral recess narrowing, L5 foraminal stenosis, and a bulging L5 to S1 disc compressing the extraforaminal nerve roots. A novel craniocaudal interlaminar approach via unilateral biportal endoscopic spine surgery was used to decompress the central and contralateral foraminal regions. The residual ipsilateral extraforaminal lesion was accessed through a separate full endoscopic transforaminal approach. Three incisions of 7 mm each were used.

Results: The patient experienced immediate and significant relief of radicular symptoms and improved function and was discharged the next day. At 18-month follow-up, he remained pain-free and without new-onset back pain or signs of instability.

Conclusions: This is the first reported case combining unilateral biportal endoscopic spine surgery and full endoscopic spine surgery. The approach enabled full decompression from central to extraforaminal zones with minimal invasiveness. This dual-endoscopic strategy may serve as a model for treating complex spine cases not amenable to single-approach techniques.

Level of evidence: 4:

Background: This study aimed to compare a 3-dimensional (3D)-printed titanium cage with a polyetheretherketone (PEEK) cage in biportal endoscopic transforaminal lumbar interbody fusion (BETLIF) using a double cage construct, evaluate differences in fusion stability and subsidence between the 2 cage types, and analyze factors influencing subsidence.

Methods: We retrospectively examined 89 patients who underwent BETLIF using a double cage (3D-printed titanium, 48 levels; PEEK, 46 levels). Fusion status and subsidence were assessed using dynamic plain lateral lumbar spine radiographs and computed tomography images at 6 months and 1 year postoperatively. Fusion was graded according to the Bridwell system, and significant subsidence was defined as ≥2 mm endplate depression on computed tomography. Demographic and clinical variables, including age, sex, body mass index, American Society of Anesthesiologists classification, history of tobacco smoking, diabetes mellitus, bone mineral density measured using dual-energy x-ray absorptiometry, cage length, and cage material, were collected and analyzed as potential risk factors.

Results: At 1-year follow-up, fusion grades were I (75.0%, 36 levels), II (20.8%, 10 levels), and III (4.2%, 2 levels) for 3D-printed titanium and I (53.2%, 25 levels), II (40.4%, 19 levels), and III (6.4%, 3 levels) for PEEK. The overall fusion rate (grades I and II) was similar for both cages (95.8% vs 93.6%, P = 0.629), but grade I was more prevalent with 3D-printed titanium than with PEEK (75.0% vs 53.2%, P = 0.027). No significant differences were observed in subsidence or complications between the 2 cages. Multivariate analysis revealed age as the only variable significantly associated with subsidence in BETLIF.

Conclusions: Both double 3D-printed titanium and PEEK cages demonstrated high fusion rates with no significant differences in overall success. However, double 3D-printed titanium cages showed better early fusion grades and comparable subsidence to that of PEEK cages. Although long-term follow-up is necessary to ascertain efficacy, these findings suggest that 3D-printed titanium cages offer advantages in early fusion quality in BETLIF. Further research is needed to optimize cage arrangement, cage design, and surgical techniques to improve outcomes.

Clinical relevance: The use of double 3D-printed titanium cages is recommended in BETLIF.

Level of evidence: 3:

Background: There are currently no studies that directly compare the previously established 2-dimensional (2D) sagittal technique with 3-dimensional (3D) templating for C2 pedicle screw.

Objective: To verify the accuracy of sagittal radiological analysis for safe placement of a C2 pedicle screw by performing a direct comparison between 2D planning with 3D templating methods.

Methods: In this retrospective analysis, forty-six sets of computed tomography scans that contained 2-mm bony cuts and 2D reconstructions in the axial, sagittal, and coronal planes of skeletally mature patients were analyzed. StealthStation S7 (Medtronic Surgical Navigation, Minneapolis, Minnesota, United States) trajectory planning was used to plan the ideal placement, maximum diameter pedicle screw into the C2 pedicle. Based on the parameters of ≤3 mm screw diameter as high risk, >3 mm and <5 mm as moderate risk, and ≥5 mm as low risk, frequency and percentage values were calculated for the left, right, and bilateral pedicle screws.

Results: Out of the 46 patients analyzed in this study, only 1 patient (2.2%) was classified as low risk (≥5 mm) bilaterally, 5 were classified as high risk (≤3 mm) bilaterally (10.8%), and 25 patients (54.3%) showed variability in pedicle width between the left and right sides. With analysis of both left and right pedicle, 7 out of 92 pedicles (7.6%) analyzed were classified as low risk (≥5 mm), 67 out of 92 (72.8%) were at moderate risk (>3 mm and <5 mm), and 18 out of 92 (19.6%) were at high risk (≤3 mm).

Conclusion: Both the previously described 2D sagittal planning method and the current 3D templating method allow for accurate preoperative planning for the placement of ≤4 mm C2 pedicle screws, which is important given the limited availability and amount of resources utilized for the 3D templating model. However, the 3D templating method more precisely identifies C2 pedicles where 3.0 to 4.5 mm screws can feasibly be placed.

Level of evidence: 3:

Background: Bilateral sacroiliac joint fusion (BSIJF) is an accepted management strategy for sacroiliac joint dysfunction, though outcomes data are limited by patient number and lack of long-term follow-up. This study investigated the clinical, radiological, and patient-reported outcomes of BSIJF.

Methods: A retrospective review was conducted of all patients who underwent BSIJF with a single surgeon between 2020 and 2023. All BSIJF utilized a principles-based approach: joint decortication, bone grafting, compression, and rigid stability. Patient-reported outcomes at preoperative, 6-month, 1-year, and 2-year follow-up timepoints were recorded for the Numeric Pain Rating Scale, Oswestry Disability Index (ODI), Single Assessment Numeric Evaluation (SANE), PROMIS Pain Interference (PI), and PROMIS Physical Function (PF). Fusion grading was assessed by computed tomography after 1 and 2 years.

Results: Forty-eight patients who underwent BSIJF were included, of whom 31 (65%) were women with a mean age of 54 ± 14 years and a mean body mass index of 29 ± 5. Twenty-five patients (52%) had prior lumbar spine surgery (PLSS). One patient required revision for implant malpositioning and nerve impingement. Bridging bone across the sacroiliac joint was observed in 85% of patients. Numeric Pain Rating Scale scores dropped significantly from 7.6 preoperatively to 3.9, 3.3, and 3.7 at 6-month, 1-year, and 2-year follow-ups, respectively (P ≤ 0.004). PI and PF scores were significantly improved at all timepoints (all P < 0.001). ODI scores demonstrated sustained improvement from 52.3 preoperatively to 33.3 at 1-year follow-up and 29.3 at 2-year follow-up (P < 0.001). SANE scores were 80% at 1-year follow-up and 85% at 2-year follow-up. PI, PF, and ODI scores were significantly improved at all timepoints, independent of PLSS status. The mean SANE score in patients with PLSS was 82% ± 22% at 2-year follow-up. Patient history of hip surgery prior to BSIJF was associated with inferior postoperative ODI and SANE scores.

Conclusions: BSIJF is a safe and effective treatment that is associated with high rates of bony bridging at the sacroiliac joint and long-term clinically significant improvements in pain and function.

Level of evidence: 4:

Background: This study aims to determine whether single-level lateral lumbar interbody fusion (LLIF) with unilateral pedicle screw fixation (UPSF) might offer advantages over bilateral pedicle screw fixation (BPSF) in terms of radiation emission, cost, and outcomes.

Methods: The records of 101 patients who underwent single-level LLIF with percutaneous pedicle screw fixation from September 2017 to August 2024 were analyzed. Patients were divided into 2 groups: 42 with UPSF and 59 with BPSF. Demographic data, social history, comorbidities, surgical characteristics, costs (based on manufacturer prices), and radiation metrics (radiation emitted, fluoroscopy time, number of images, and magnification mode used) were collected. Clinical outcomes were assessed using the Numeric Rating Scale (NRS), the Oswestry Disability Index, and procedure satisfaction, while radiographic evaluation employed a novel fusion classification system.

Results: There were no significant differences in age, body mass index, social history, comorbidities, or operative level. However, the BPSF group included significantly more women (P = 0.002) and a higher proportion of spondylolisthesis cases (P < 0.001). Oswestry Disability Index and NRS scores were similar, except for greater improvements in NRS back pain at 1 year in the BPSF group (-4.0 vs -1.75, P = 0.008). While the total fluoroscopy time, number of images, and Mag 1 usage were greater in the BPSF group (all P < 0.001), the average radiation emitted did not significantly differ (39.38 milligray for UPSF vs 50.75 milligray for BPSF, P = 0.211). Fusion grades were comparable (P = 0.478), and UPSF costs were 27.7% lower.

Conclusions: Our study found that when used according to clinical indications, UPSF results in similar radiation emission and radiographic outcomes, while being 27.7% less expensive than BPSF for single-level LLIF. Additionally, while BPSF was associated with greater improvement in 1 year NRS back scores, no other significant differences in patient-reported outcome measures were observed between the 2 groups.

Clinical relevance: This study provides clinically relevant insights for selecting between UPSF and BPSF in single-level LLIF when both are considered appropriate.

Level of evidence: 3:

Background: Computerized navigation improves the accuracy of spine procedures. However, intraoperative imaging is plagued by ionizing irradiation and its cancer risk. Advanced technologies attempt to optimize the radiation dose. The goal of this study was to compare radiation exposure and screw accuracy of O-arm navigation and the Surgivisio device (SD) in pedicle screw insertion.

Methods: All patients operated on by navigated pedicle screw insertion during a 19-month period were prospectively included in 2 spine centers: the first with the O-arm and the second with the SD. Demographic, operative, and irradiation data were collected. The accuracy of the screw positioning was assessed using the Heary and Gertzbein classifications. The effective dose in millisievert (mSv) was calculated.

Results: One hundred patients were included, 50 per group. Five hundred and twelve screws were inserted, among them 228 in 120 vertebrae with the O-am and 284 in 145 vertebrae with the SD. Screw accuracy was 99.1% with the O-arm vs 93.3% with the SD (P = 0.07). Operative times were similar, with 145 vs 139 minutes respectively, P = 0.68. The effective dose was significantly higher in the O-arm group, with 5.43 vs 2.70 mSv with the SD (P < 0.01). The effective dose related to 2-dimensional imaging was significantly lower in the O-arm group than in the SD group, with 0.26 vs 1.16 mSv, respectively, P < 0.01, related to a shorter imaging duration (4 vs 109 seconds respectively, P < 0.01).

Conclusions: Accuracy of pedicle screws was higher with the O-arm than with the Surgivisio, but the latter showed less radiation exposure. Despite promising results, improvements in technology should be pursued for ergonomics and surgical safety.

Level of evidence: 4:

Background: Individually, robotic guidance and 3-dimensional navigation assistance have been shown to improve surgical outcomes and accuracy in spine surgery. The pairing of these technologies may further improve outcomes; however, data are needed to support this theory. In the Prospective Robotic-Guided Registry of Spine Surgery (PRoGRSS), outcomes were tracked for cases using a bone-mounted integrated robotic-assisted navigation system. This interim analysis reports on 90-day complications and revisions.

Methods: Adults undergoing navigated robotic thoracolumbar surgery from 2020 to 2022 were prospectively enrolled by 6 surgeons at 4 distinct centers. Medical, surgical, and robot-related complications and revision surgeries were collected postoperatively for up to 90 days and analyzed.

Results: Of 411 surgeries, 3469 screws were implanted. The mean number of levels fused was 4.4 ± 3.7. Intraoperative adverse events occurred in 4.1% of cases, and 0.5% were robot related. The frequency of patients with at least 1 postoperative surgical complication was 6.6%, none being robot related. The frequency of patients with at least 1 postoperative medical complication was 18.2%. The revision surgery rate at 90 days was 1.5%, none of which were robot related.

Conclusion: This first-of-its-kind study of an integrated navigation and robotic spine platform demonstrates low complication and revision surgery rates for thoracolumbar fusion. This interim analysis of PRoGRSS showed 4.1% intraoperative complications, 6.6% postoperative surgical complications, and 1.5% revision surgeries. With advancements in technology and increased surgical expertise, navigated robotics continues to demonstrate consistently low rates of 90-day complications and revision surgeries, supporting its reliability.

Clinical relevance: The interim analysis of PRoGRSS suggests that the integration of robotic guidance with 3-dimensional navigation is reproducibly effective in the surgical setting.

Level of evidence: 2:

Background: We sought to better understand the current decision-making criteria and surgical strategies for pelvic fixation in spinal surgery.

Methods: A 28-question survey was distributed to an international group of practicing spine surgeons. Questions included training, practice type, criteria for using pelvic fixation, and strategies for pelvic fixation, including the type and technique employed.

Results: Of the 56 responders, 32% were neurosurgeons, and 67% were affiliated with academic institutions. Factors that most influenced the use of pelvic fixation were 3-column osteotomy (3CO), high-grade spondylolisthesis, and L5 to S1 pseudarthrosis. Most report using a single point of pelvic fixation per side for the following: deformity 4+ levels without 3CO (55%) and spondylolisthesis grade 3 (59%). The upper instrumented vertebra threshold for pelvic fixation in degenerative pathology was L2 (70%) or L3 (16%). Most surgeons chose 2 points of fixation per side in the setting of 4 or more levels with 3CO (69%) and revision of at least 3 levels (68%). The predominant (77.6%) fixation preference was S2-alar-iliac screws. Surgeons report using navigation (70%), fluoroscopy (23%), free hand (21%), and robot-assisted (7%) for screw placement. The most common pelvic screw diameter and length were 8.5 mm and 90 mm, respectively. A 5% to 10% pelvic fixation revision rate was reported, primarily for instrumentation failure or pseudarthrosis.

Conclusion: This survey-based study highlights factors influencing surgeons' decisions on pelvic instrumentation. While complex corrections or revisions often require robust fixation, variability arises in simpler cases, influenced by factors like age, obesity, and bone quality.

Level of evidence: 4: