International Journal of Spine Surgery最新文献

Background: Tubular spine surgery has emerged as a hallmark of minimally invasive spine (MIS) procedures. In recent years, thanks to technological advances, tubular dilators and retractors have been integrated with digital cameras to allow for ergonomic, high-definition visualization of the surgical field.

Objective: To detail the evolution, ergonomics, economics, and outcomes of camera-based tubular spine surgery, spanning the origins of MIS tubular techniques to the current use of operative microscopes and tube-mounted digital cameras (TMDCs).

Methods: This is a narrative review of studies examining the evolution of tubular spine surgery as well as its most recent advances, with a particular emphasis on advances in visualization of the surgical field.

Results: Despite early resistance to tubular techniques due to a steep learning curve, minimally invasive tubular approaches are being increasingly adopted by the mainstream spine surgical community, which has resulted in an expansion of both indications and procedural modalities. This can largely be attributed to the increased quality of visualization, as evidenced by improvements in microscopes as well as emerging technologies like exoscopes and TMDCs. Tubular MIS procedures have also achieved superior efficacy compared with open surgical approaches for the treatment of several spinal pathologies while allowing for improved ergonomics, which may have lasting consequences on surgeon longevity.

Conclusions: Advances in visualization technologies have allowed tubular surgery to become an effective, ergonomic, and muscle-sparing alternative to open spine surgery. Further research is necessary to quantify the true costs and outcomes associated with nascent TMDC technology.

Clinical relevance: This work elucidates developments in visualization for tubular spine surgery.

Level of evidence: 5:

Background: Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment. Recently, personalized spine surgery has witnessed significant advancements, including 3D-printed personalized interbody implants, which are customized to the surgeon's treatment and alignment goals. This study evaluates the reliability of 3D-printed patient-specific interbody implants to achieve the planned postoperative intervertebral alignment.

Methods: This is a retrospective study of 217 patients with spinal deformity or degenerative conditions. Patients were included if they received 3D-printed personalized interbody implants. The desired intervertebral lordosis (IVL) angle was prescribed into the device design for each personalized interbody (IVL goal). Standing postoperative radiographs were measured, and the IVL offset was calculated as IVL achieved minus IVL goal.

Results: In this patient population, 365 personalized interbodies were implanted, including 145 anterior lumbar interbody fusions (ALIFs), 99 lateral lumbar interbody fusions (LLIFs), and 121 transforaminal lumbar interbody fusions. Among the 365 treated levels, IVL offset was 1.1° ± 4.4° (mean ± SD). IVL was achieved within 5° of the plan in 299 levels (81.9%). IVL offset depended on the approach of the lumbar interbody fusion and was achieved within 5° for 85.9% of LLIF, 82.6% of transforaminal lumbar interbody fusions and 78.6% of ALIFs. Ten levels (2.7%) missed the planned IVL by >10°. ALIF and LLIF levels in which the plan was missed by more than 5° tended to be overcorrected.

Conclusions: This study supports the use of 3D-printed personalized interbody implants to achieve planned sagittal intervertebral alignment.

Clinical relevance: Personalized interbody implants can consistently achieve IVL goals and potentially impact foundational lumbar alignment.

Level of evidence: 4:

Background: Emerging data have highlighted the significance of planning and aligning total and segmental lumbar lordosis with pelvic morphology when performing short-segment fusion with the goal of reducing the risk of adjacent segment disease while also decreasing spine-related disability. This study evaluates the impact of personalized interbody implants in restoring pelvic incidence-lumbar lordosis (PI-LL) mismatch compared with a similar study using stock interbody implants.

Methods: This multicenter retrospective analysis assessed radiographic pre- and postoperative spinopelvic alignment (PI-LL) in patients who underwent 1- or 2-level lumbar fusions with personalized interbody implants for degenerative (nondeformity) indications. The aim was to assess the incidence of malalignment (PI-LL ≥ 10°) both before and after fusion surgery and to determine the rate of alignment preservation and/or correction in this population.

Results: There were 135 patients included in this study. Of 83 patients who were aligned preoperatively, alignment was preserved in 76 (91.6%) and worsened in 7 (8.4%). Among the 52 preoperatively malaligned patients, alignment was restored in 23 (44.2%), and 29 (55.8%) were not fully corrected. Among patients who were preoperatively aligned, there was no statistically significant difference in either the "preserved" or "worsened" groups between stock devices and personalized interbody devices. In contrast, among patients who were preoperatively malaligned, there was a statistically significant increase in the "restored" group (P = 0.046) and a statistically significant decrease in the "worsened" groups in patients with personalized interbodies compared with historical stock device data (P < 0.05).

Conclusions: Compared with a historical cohort with stock implants, personalized interbody implants in short-segment fusions have shown a statistically significant improvement in restoring patients to normative PI-LL. Using 3-dimensional preoperative planning combined with personalized implants provides an important tool for planning and achieving improvement in spinopelvic parameters.

Level of evidence: 3:

Background: Adult spinal deformity (ASD) surgery often involves the placement of pedicle screws using various methods, including freehand technique, fluoroscopic guidance, and computer-assisted intraoperative navigation, each with distinct limitations. Particularly challenging is the instrumentation of pedicles with small or absent cancellous channels (Watanabe types C and D pedicles), commonly found at the apex of large curves where precise screw placement is crucial for effective deformity correction. 3D-printed pedicle screw drill guides (3DPSG) may assist in accurately placing pedicle screws while minimally disrupting the standard ASD surgery workflow. This study aims to evaluate the safety and efficacy of 3DPSG in ASD patients with Watanabe types C and D pedicles, where the safe corridor for screw placement is limited.

Methods: 3DPSG were designed using fine cut (≤1.25 mm) computed tomography scans. Preoperative screw trajectory planning and guide manufacturing were conducted using computer-aided design software (Mighty Oak Medical, Englewood, CO). Four ASD surgeons with varying experience levels placed the guides. Data on patient demographics, pedicle morphology, number of levels instrumented, and implant-related complications were collected.

Results: The study included 115 patients (median age 67, range 18-81 years) with 2210 screws placed from T1 to L5. The median number of levels instrumented per case was 11 (range 7-12). Diagnoses included adult degenerative scoliosis (n = 62), adult idiopathic scoliosis (n = 30), Scheuermann's kyphosis (n = 2), and other complex conditions (n = 21). The overall accuracy rate for pedicle screw placement was 99.5%, with a 0% malposition rate in type C and D pedicles. No vascular or neurological complications or reoperations related to screw placement were reported.

Conclusion: 3DPSG facilitates safe and accurate pedicle screw placement regardless of pedicle morphology in ASD surgeries. This includes the challenging Watanabe types C and D pedicles, typically found at curve apices, enabling surgeons to achieve high implant density and optimal spinal fixation in ASD patients.

Level of evidence: 4:

Background: An abnormal postoperative lordosis distribution index (LDI), which quantifies the ratio between the lordosis at L4 to S1 and the lordosis at L1 to S1, contributes to the development of adjacent segment disease and increased revision rates in patients undergoing short-segment lumbar intervertebral fusions. Incorporating preoperative spinopelvic parameters and LDI into the surgical plan for short-segment fusion is important for guiding alignment restoration and preserving normal preoperative alignment in unfused segments. This study examined changes in LDI, segmental lordosis, and lordosis of the unfused levels in patients treated with personalized interbody cage (PIC) implants.

Methods: This retrospective study evaluated radiographic measurements from 111 consecutively treated patients diagnosed with degenerative spinal conditions and treated with a short-segment fusion of L4 to L5, L5 to S1, or L4 to S1 using PIC implant(s) within 6 months of the fusion procedure. Comparisons of intervertebral lordosis for treated and untreated levels as well as LDI pre- and postoperatively were performed.

Results: In patients with a preoperative hypolordotic distribution (LDI < 50%), statistically significant increases were found in LDI postoperatively, approaching the normal LDI range (LDI 50%-80%). Likewise, patients with hyperlordotic distribution preoperatively (LDI > 80%) experienced a decrease in LDI postoperatively, trending toward the normal range, although the changes were not statistically significant. Intervertebral lordosis for the L5 to S1 level increased significantly following the placement of a PIC in the normal and hypolordotic LDI groups. Changes in intervertebral lordosis for L5 to S1 were not significant for patients with preoperative hyperlordotic LDI. Reciprocal changes in intervertebral lordosis at L1 to L4 were not observed in any groups.

Conclusions: PIC implants may provide a benefit for patients, particularly those with hypolordotic distributions preoperatively. They have the potential to further improve patient outcomes by helping surgeons to achieve patient-specific lordosis goals, which may help to reduce the risk of adjacent segment disease and revisions in patients undergoing short-segment lumbar intervertebral fusions.

Clinical relevance: Personalized implants can help surgeons achieve patient-specific alignment goals, potentially prevent adjacent segment disease, and reduce long-term reinterventions.

Level of evidence: 4:

Background: Incongruity between irregularly shaped vertebral endplates and the uniform surfaces of stock interbody fusion cages has been identified as contributing to cage subsidence, pseudarthrosis, and unpredictable alignment. Advances in manufacturing techniques have driven the development of personalized interbody cages (PICs) that can match individual endplate morphology and provide the exact shape and size needed to fill the disc space and achieve the planned correction. This study used computed tomography (CT) imaging to evaluate the implant-endplate contact area, fusion, subsidence, and achievement of planned alignment correction in patients receiving PIC devices.

Methods: This retrospective study included patients treated for adult spinal deformity at a single site and implanted with PIC devices at L4 to L5 or L5 to S1 for segmental stabilization and alignment correction, who received 1-year postoperative CT images as part of their standard of care. An evaluation using 3-dimensional thin-section scans was conducted. Implant-endplate contact and signs of fusion were assessed in each CT slice across both endplates. The degree of subsidence as well as measures of segmental and global lumbar alignment were also assessed.

Results: Fifteen patients were included in the study, with a mean age of 68.2 years. Follow-up ranged between 9 and 14 months. Twenty-six total lumbar levels were implanted; 20 with PIC devices via the anterior lumbar interbody fusion approach, 2 with stock cages via the anterior lumbar interbody fusion approach, and 4 with PIC devices via the transforaminal lumbar interbody fusion approach. CT analysis of PIC-implanted levels found an overall implant-endplate contact area ratio of 93.9%, a subsidence rate of 4.5%, a fusion rate of 100%, and satisfactory segmental and global lumbar correction compared with the preoperative plan.

Conclusions: PIC implants can provide nearly complete contact with endplate surfaces regardless of the individual endplate morphology. Subsidence, fusion, and alignment assessments in this tomographic study illustrated results consistent with the benefits of a personalized interbody implant.

Level of evidence: 4:

Background: Literature supports the need for improved techniques to achieve spinopelvic alignment and reduce complication rates in patients with adult spinal deformity (ASD). Personalized interbody devices were developed to address this need and are under evaluation in the multicenter Clinical Outcome Measures in Personalized aprevo (circle R superscript) Spine Surgery (COMPASS (TM suprascript) registry. This report presents interim COMPASS pre- and postoperative sagittal alignment results and complication rates for a subcohort of COMPASS patients diagnosed and surgically treated for spinal deformity.

Methods: COMPASS is a postmarket observational registry of patients enrolled either before or after index surgery and then followed prospectively for 24 months. Sagittal alignment was assessed with SRS-Schwab modifiers for pelvic incidence minus lumbar lordosis, pelvic tilt, and T1 pelvic angle. Summed SRS-Schwab modifiers were utilized to assign overall deformity status as mild, moderate, or severe. Complications were extracted from patient medical records.

Results: The study included 67 patients from 9 centers. Preoperative severe deformity was observed in 66% of patients. Index surgeries included implantation of a median of 2 personalized interbody devices by anterior, lateral, or transforaminal approaches and with a median of 8 posteriorly instrumented levels. Overall postoperative sagittal alignment improved with a significant decrease in the mean sum of SRS-Schwab modifiers that correlated strongly to improvements in pelvic incidence minus lumbar lordosis. Among 44 patients with preoperative severe overall deformity, 16 improved to moderate and 9 to mild deformity. Complications occurred for 13 patients (19.4%), including 1 mechanical complication requiring revision 9 months after surgery and none related to personalized interbody devices.

Conclusions: This study demonstrates that ASD patients whose treatment included personalized interbody devices can obtain favorable postoperative alignment status comparable to published results and with no complications related to the personalized interbody devices.

Clinical relevance: This study contributes to growing evidence that personalized interbody devices contribute to improved sagittal alignment in ASD patients by directly adjusting the orientation of adjacent vertebra.

Level of evidence: 3:

Spinal deformity surgery often requires complex surgical interventions that can have a drastic effect on both patient quality of life and functional capacity. Modern-day corrective solutions for these deformities include spinal osteotomies, pedicle screw instrumentation, and dual/multirod constructs. These solutions are efficacious and are currently considered standard practice for spinal surgeons, but they lack individualization. Patient-specific rods (PSRs) are a novel technology that attempts to offer a personalized approach to spinal deformity correction based on preoperative computerized tomography scans. Moreover, PSRs may offer several advantages to conventional rods, which include achievement of desired rod contour angles according to surgical planning alignment goals, reduced operative time, and reduced blood loss. In adolescent idiopathic scoliosis, those instrumented with PSR have observed coronal Cobb reductions up to 74%. In adult spinal deformity, PSRs have offered superior correction in radiographic parameters such as sagittal vertical axis and pelvic incidence minus lumbar lordosis. However, there still remains a paucity of research in this area, mainly in health care expenditure, cost-effectiveness, and longitudinal clinical outcomes. The purpose of this article is to survey the current body of knowledge of PSR instrumentation in both adolescent and adult spinal deformity populations. The current strength, limitations, and future directions of PSRs are highlighted throughout this article.