Vertebral body tethering for Lenke 1A curves: the lumbar modifier predicts less optimal outcomes

INTRODUCTION

The addition of the L4 "AR" and "AL" lumbar modifier for Lenke 1A idiopathic scoliosis (IS) has been shown to direct treatment in posterior spinal fusion; however, its utility in vertebral body tethering (VBT) has yet to be evaluated.

METHODS

A review of a prospective, multicenter database for VBT in IS was performed for patients with Lenke 1A deformities and a minimum of 2 years follow-up. Patients were categorized by their lumbar modifier (AR vs AL). Less optimal VBT outcome (LOVO) was defined as a final coronal curve > 35°, lumbar adding-on, or revision surgery for deformity progression or adding-on.

RESULTS

Ninety-nine patients met inclusion criteria (81% female, mean 12.6 years), with 55.6% being AL curves. Overall, there were 23 instances of tether breakage (23.3%) and 20 instances of LOVO (20.2%). There was a higher rate of LOVO in AR curves (31.8% vs 10.9%, P = 0.01). Patients with LOVO had greater preoperative deformity, greater apical translation, larger coronal deformity on first erect radiographs, and less coronal deformity correction. Failure to correct the deformity < 30° on first erect was associated with LOVO, as was LIV selection short of the last touch vertebra (TV). Independent risk factors for LOVO included AR curves (OR 3.4; P = 0.04) and first erect curve magnitudes > 30 degrees (OR 6.0; P = 0.002).

DISCUSSION

There is a 20.2% rate of less optimal VBT following VBT for Lenke 1A curves. AR curves are independently predictive of less optimal outcomes following VBT and require close attention to LIV selection. Surgeons should consider achieving an initial coronal correction < 30 degrees and extending the LIV to at least the TV to minimize the risk of LOVO.

Double major curvature treated with vertebral body tethering of both curves: how do outcomes compare to posterior spinal fusion?

PURPOSE

Vertebral body tethering (VBT) is a non-fusion alternative to posterior spinal fusion (PSF). There have been few reports on VBT of two curvatures. We aim to compare the radiographic outcomes between VBT and PSF in patients with double curvatures in which both curves were instrumented.

METHODS

29 AIS patients matched by Lenke, age (± 2 years), triradiate cartilage closure status, major Cobb angle (± 8°), and T5-T12 kyphosis (± 10°). Variables were compared using Wilcoxon rank-sum tests, Student's t tests, and chi-Square. Clinical success was defined as major curve < 35°.

RESULTS

Group baseline demographics were similar. Major thoracic (T) curve types had significantly better major (VBT 51.5 ± 7.9° to 31.6 ± 12.0° [40%] vs. PSF 54.3 ± 7.4° to 17.4 ± 6.5° [68%]; p = 0.0002) and secondary curve correction in the PSF group. 71% of major T VBT patients were clinically successful versus 100% of PSF. Major thoracolumbar (TL) curve types experienced comparable major (VBT 52.3 ± 7.0° to 18.3 ± 11.4° (65%) vs. PSF 53.0 ± 5.2° to 23.8 ± 10.9° (56%); p = 0.2397) and secondary curve correction. 92% of major TL VBT patients were clinically successful versus 75% in the PSF group. There was no difference in T5-12 kyphosis or lumbar lordosis between groups for any curve type. There were 4 patients (13.8%) with major complications in the VBT group compared to 0 (0%) in the PSF.

CONCLUSION

Patients with double major AIS who underwent VBT with major T curve types had less correction than PSF; however, those with major TL curves experienced similar radiographic outcomes regardless of procedure. Complications were greater for VBT.

Vertebral body tethering for adolescent idiopathic scoliosis: a review

PURPOSE

Adolescent Idiopathic Scoliosis (AIS) remains the most common type of pediatric scoliosis, mostly affecting children between ages 10 and 18. Vertebral body tethering (VBT) offers a non-fusion alternative to the gold standard spinal fusion that permits flexibility and some growth within instrumented segments. This article will serve as a comprehensive literature review of the current state-of-the-art of VBT in relation to radiographic and clinical outcomes, complications, and the learning curve associated with the procedure.

METHODS

A systematic literature review was conducted on PubMed, Scopus, and Web of Science from April 2002 to December 2022. Studies were included if they discussed VBT and consisted of clinical studies in which a minimum 2-years follow-up was reported, and series that included anesthetic considerations, learning curve, and early operative morbidity.

RESULTS

Forty-nine studies spanning the period from April 2002 to December 2022 were reviewed.

CONCLUSION

This article illustrates the potential benefits and challenges of the surgical treatment of AIS with VBT and can serve as a basis for the further study and refinement of this technique ideally as a living document that will be updated regularly.

Changes in the centre of rotation and the anterior bone loss of the vertebral body in Mobi-C artificial disc replacement segments after cervical hybrid surgery: a retrospective study

OBJECTIVE

To examine the short-term efficacy and imaging results of using the Mobi-C in cervical hybrid surgery on 2-level cervical spondylolisthesis. To observe post-operative changes in the flexion-extension centre of rotation (FE-COR) and anterior bone loss (ABL) of the anterior cervical disc replacement (ACDR) segment.

METHODS

Forty-two patients (20 males and 22 females, aged 42‒67 years) who underwent cervical hybrid surgery were retrospectively analysed. Their ACDR segment used Mobi-C, and the fusion segment used ROI-C, with a follow-up of 25‒42 months (31.1 ± 4.8 months). The modified Japanese Orthopaedic Association (mJOA) score, Neck Disability Index (NDI), and visual analogue scale (VAS) were used to assess clinical outcomes. Pre-operative, 6-month post-operative, and final follow-up radiographs were collected to compare total cervical spine curvature (C2-C7), curvature of the operated segments, range of motion (ROM) in the total cervical spine, operated segmental ROM, ACDR segmental ROM, and operated adjacent segmental ROM. The height of the superior articular process (HSAP), the orientation of zygapophyseal joint spaces (OZJS), and the length of the superior articular surface (LSAS) were measured. The FE-COR of the ACDR segment was measured using the mid-plumb line method. The translation distance of the Mobi-C was measured. The degree of disc degeneration in the adjacent segment, bony fusion of the ACDF segment, and ABL of the upper and lower vertebra of the ACDR segment were observed.

RESULTS

In our group, all patients have shown improvements in their postoperative mJOA, NDI, and VAS scores. Overall cervical ROM and surgical segmental ROM decreased (P < 0.05). However, there was no significant decrease in ACDR segmental ROM and upper or lower adjacent segmental ROM compared with pre-operatively (P > 0.05). For FE-COR-X, only the last follow-up compared with pre-surgery showed statistical significance (46.74 ± 7.71% vs. 50.74 ± 6.92%, P < 0.05). For FE-COR-Y, the change was statistically significant at both 6 months post-operation and the final follow-up compared to pre-operation (45.37% ± 21.11% vs. 33.82% ± 10.87%, 45. 37% ± 21.11% vs. 27.48% ± 13.58%, P < 0.05). No significant difference in the Mobi-C translation distance was observed (P > 0.05). Moreover, the difference in HSAP was not statistically significant at each node (P > 0.05). The OZJS and LSAS were significantly different at the final follow-up compared to the pre-operative period (P < 0.05). All the ACDF segments were observed in a stable condition at the final follow-up. Furthermore, 9 of the adjacent segments showed imaging ASD (9/82, 10.98%), and all were present at the last follow-up, of which 6 were mild, and 3 were moderate. Twenty of the 42 Mobi-C segments had no significant ABL (grade 0) 6 months post-operatively (47.62%). Sixteen cases (38.10%) showed mild ABL (grade 1), and 6 cases (14.28%) showed moderate ABL (grade 2). No severe ABL occurred.

CONCLUSION

The cervical hybrid surgery using Mobi-C artificial cervical discs can achieve satisfactory results. The Mobi-C segmental FE-COR-X shows a slow forward shift trend, and FE-COR-Y drops noticeably within 6 months post-surgery before stabilizing. It's common to see mild to moderate ABL after cervical hybrid surgery using Mobi-C, and significant progression is unlikely in the short term. Furthermore, changes in the FE-COR after hybrid surgery in the Mobi-C segment might not affect clinical outcomes.

Percutaneous transforaminal endoscopic decompression with removal of the posterosuperior region underneath the slipping vertebral body for lumbar spinal stenosis with degenerative lumbar spondylolisthesis: a retrospective study

BACKGROUND

Percutaneous transforaminal endoscopic decompression (PTED) is an ideal minimally invasive decompression technique for the treatment of lumbar spinal stenosis (LSS) with degenerative lumbar spondylolisthesis (DLS). The posterosuperior region underneath the slipping vertebral body (PRSVB) formed by DLS is an important factor exacerbating LSS in patients. Therefore, the necessity of removing the PRSVB during ventral decompression remains to be discussed. This study aimed to describe the procedure of PTED combined with the removal of the PRSVB and to evaluate the clinical outcomes.

METHODS

LSS with DLS was diagnosed in 44 consecutive patients at our institution from January 2019 to July 2021, and they underwent PTED combined with the removal of the PRSVB. All patients were followed up for at least 12 months. The clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and modified MacNab criteria.

RESULTS

The mean age of the patients was 69.5 ± 7.1 years. The mean preoperative ODI score, VAS score of the low back, and VAS score of the leg were 68.3 ± 10.8, 5.8 ± 1.0, and 7.7 ± 1.1, respectively, which improved to 18.8 ± 5.0, 1.4 ± 0.8, and 1.6 ± 0.7, respectively, at 12 months postoperatively. The proportion of patients presenting "good" and "excellent" ratings according to the modified MacNab criteria was 93.2%. The percent slippage in spondylolisthesis preoperatively (16.0% ± 3.3%) and at the end of follow-up (15.8% ± 3.3%) did not differ significantly (p>0.05). One patient had a dural tear, and one patient had postoperative dysesthesia.

CONCLUSIONS

Increasing the removal of PRSVB during the PTED process may be a beneficial surgical procedure for alleviating clinical symptoms in patients with LSS and DLS. However, long-term follow-up is needed to study clinical effects.

Overloaded vertebral body: a unique radiographic phenomenon following multilevel anterior cervical discectomy and fusion

PURPOSE

Because previous studies have not focused on postoperative cervical collapse, the purpose of the present study was to introduce the overloaded vertebral body (OVB) phenomenon following multilevel zero-profile anterior cervical discectomy and fusion (ACDF) as well as to investigate its effects on radiographic outcomes.

METHODS

We conducted a retrospective study involving patients who underwent ACDF. A total of 55 patients were included in the analysis, including 110 OVB and 110 non-OVB. The evaluated vertebral parameters included the vertebral cross-sectional area (CSA), wedge angle (WA), vertebral height [anterior (AH) and posterior (PH)] and anterior-posterior vertebral diameter [upper (UD) and lower (LD)].

RESULTS

The CSA and WA were significantly lower in the OVB group than in the non-OVB group at 3, 6, and 12 months after surgery as well as at the final follow-up (p < 0.01). The AH of the OVB group was significantly lower at 3, 6, and 12 months after surgery as well as at the final follow-up compared to 1 week after surgery (p < 0.01).

CONCLUSIONS

OVB, a new phenomenon following multilevel ACDF, is defined as the cervical vertebral body located in the middle of the surgical segments in multilevel anterior cervical spine surgery. Statistical analysis of vertebral parameters, including CSA, WA, AH, PH, UD, and LD, showed that OVB occurs mainly at the anterior edge of the vertebra and that its largest radiographic manifestation is the loss of height at the anterior edge of the vertebra in the early postoperative period.

Vertebral Body Infarction after Transarterial Preoperative Embolization of a Vertebral Hemangioma

BACKGROUND

 Vertebral hemangioma resection can be a real challenge for spine surgeons, given the high potential of massive intraoperative bleeding. For this reason, preoperative transarterial embolization of this tumor is supported by the available literature. Here, we discuss our difficulties in interpreting an unusual clinical and radiologic picture related to the endovascular procedure.

METHODS AND RESULTS

 A 45-year-old man was referred to our department due to chronic back pain and progressive lower extremity weakness. Radiologic assessment was obtained by means of spinal computed tomography (CT) and magnetic resonance imaging (MRI), which showed an aggressive vertebral hemangioma in T7, compressing the spinal cord. The patient underwent a combined therapeutic approach consisting of preoperative transarterial embolization followed by tumor resection, spinal cord decompression, and posterior thoracic arthrodesis. The patient was dismissed with neither strength nor sensory deficits. Two weeks later, he returned to our department with fever. A new MRI demonstrated multiple areas of altered signal in almost all vertebral bodies from T6 down to the sacrum. After a deep diagnostic process, including new MRI and infectious disease evaluations, the definitive diagnosis of multiple vertebral bone infarction was suggested.

CONCLUSION

 Vertebral infarctions are an extremely rare complication of spinal endovascular procedures. To our knowledge, this is the first case of multiple postembolization vertebral infarctions, without spinal cord involvement. This peculiarity was explained by the presence of direct anastomoses between a posterior intercostal artery and the underlying vertebral bodies.

Static mechanical analysis of the vertebral body after modified anterior cervical discectomy and fusion (partial vertebral osteotomy): a finite element model

BACKGROUND

Modified anterior cervical discectomy and fusion (Mod ACDF) can effectively address ossification of the posterior longitudinal ligament (OPLL), which is difficult to remove directly from the posterior edge of the vertebral body, with considerably lesser damage as compared to anterior cervical corpectomy and fusion (ACCF). We compared the static mechanics of different anterior approaches by using an ideal finite element model.

METHODS

A complete finite element model was established and classified into the following three surgical models according to different model cutting operations: ACDF, ACCF, and Mod ACDF. Three different bone volume situations (normal bone mineral density, osteopenia, and osteoporosis) were simulated. After fixing the lower surface of C5 or C6, a load was applied to the upper surface of C4, and the stress distribution and displacement of the upper surface of C5 or C6 were observed and the related values were recorded.

RESULTS

The average Von Mises Stress and displacement levels of Mod ACDF were between those of ACDF and ACCF; with the peak Von Mises Stress occurring on the posterior side of the vertebral body (Points 1-4). The change in Von Mises Stress of the vertebral body is not significant during bone loss. However, the degree of displacement of the vertebral body surface and risk of vertebral collapse are increased (100 N: 13.91 vs. 19.47 vs. 21.62 μm; 150 N: 19.60 vs. 29.30 vs. 31.64 μm; 200 N: 28.53 vs. 38.65 vs. 44.83 μm).

CONCLUSIONS

The static biomechanical effects caused by Mod ACDF are intermediate between ACDF and ACCF, and the risk of vertebral body collapse is lower than that by ACCF. Therefore, Mod ACDF may be an effective solution when targeting OPLL with poorly positioned posterior vertebral body edges.

Comparison of clinical outcomes of modified laminoplasty with preservation of muscle group inserted into C2 and C7 spinous processes versus conventional C3-C7 laminoplasty: a prospective, randomized, controlled, noninferiority trial

BACKGROUND

The efficacy and noninferior of performing modified double-door laminoplasty (MDDL) (C4-C6 laminoplasty plus C3 laminectomy, alongside a dome-like resection of the inferior part of the C2 lamina and the superior part of the C7 lamina) in patients with multilevel cervical spondylotic myelopathy (MCSM) is equivocal. A randomized, controlled trial is warranted.

OBJECTIVE

The objective was to evaluate the clinical efficacy and noninferior of MDDL compared with traditional C3-C7 double-door laminoplasty.

STUDY DESIGN

A single-blind, randomized, controlled trial.

METHODS

A single-blind, randomized, controlled trial was conducted in which patients who with MCSM with greater than or equal to 3 levels of spinal cord compression from the C3 to the C7 vertebral levels were enrolled and assigned to undergo either MDDL group or conventional double-door laminoplasty (CDDL) group in a 1:1 ratio. The primary outcome was the change in the Japanese Orthopedic Association score from baseline to 2-year follow-up. The secondary outcomes included changes in the Neck Disability Index (NDI) score, the Visual Analog Scale (VAS) for neck pain, and imaging parameters. Operative complications were also collected and reported. The outcome measures were compared between the groups at 3 months, 1 year, or 2 years after surgery.

RESULTS

A total of 96 patients (mean age 67 years, 39.8% women) underwent randomization. Of these patients, 93 completed 3-month follow-up, 79 completed 1-year follow-up, and 66 completed 2-year follow-up. The changes in the Japanese Orthopedic Association score did not differ significantly between the study groups at the three time points after surgery. With respect to amelioration of neck pain and disability related to neck pain, patients in the MDDL group had a significantly greater decrease in the VAS and NDI component summary score than did those in the CDDL group at 1-year (VAS: -2.5 vs. -3.2, difference -0.7, 95% CI -1.1 to -0.2, P =0.0035; NDI: -13.6 vs. -19.3, difference -5.7, 95% CI -10.3 to -1.1, P =0.0159) and 2-years (VAS: -2.1 vs. -2.9, difference -0.8, 95% CI -1.4 to -0.2, P =0.0109; NDI: -9.3 vs. -16.0, difference -6.7, 95% CI -11.9 to -1.5, P =0.0127). The changes in the range of motion (ROM), the C2-C7 Cobb angle, and the cervical sagittal vertical axis in the MDDL group were significantly less than those in the CDDL group (ROM: -9.2±6.4 vs. -5.0±6.0, P =0.0079; C2-C7 Cobb angle: -7.9±7.8 vs. -4.1±6.2, P =0.0345; cervical sagittal vertical axis: 0.6±0.9 vs. 0.2±0.6, P =0.0233). The MDDL group had less blood loss (428.1 vs. 349.1, P =0.0175) and a lower rate of axial symptoms (27.3 vs. 6.1%, P =0.0475) than the CDDL group.

CONCLUSIONS

Among patients with MCSM, the MDDL produced similar cervical cord decompression compared with the conventional C3-C7 double-door laminoplasty. The modified laminoplasty was associated with meaningful improvement in amelioration of neck discomfort, maintaining a better cervical ROM and sagittal alignment, decreasing blood loss, and reducing the incidence of axial symptoms.

Rosai-Dorfman disease with spine involvement: A case report

RATIONALE

Rosai-Dorfman disease (RDD) is a rare, benign, self-limiting disease, also known as sinus histiocytosis with giant lymphadenopathy. Skeletal involvement is rare, and this isolated bone lesion usually occurs in adults with no other symptoms. It is estimated that 0.6% to 1% of RDD cases have isolated or complicated spinal lesions, which may occur in the bone, dura, and spinal parenchyma, but spinal RDD has no pathologic clinical or imaging features.

PATIENT CONCERNS

A 25-year-old woman presented with complaints of low back pain without obvious causes for a month.

DIAGNOSIS

RDD with spinal involvement.

INTERVENTIONS

Resection of the spinous process of the third lumbar spine was performed under epidural anesthesia.

OUTCOMES

At the time of discharge, the patient had no problems with autonomous activities and reported no discomfort. We also followed up the patient at 12 and 36 months after surgery, and the patient reported no discomfort, inconvenience, and no recurrence of symptoms. Imaging examination 1 year after surgery showed no recurrence.

LESSON

This case suggests that surgery for RDD with spinal involvement may not require internal fixation.

Vertebral Body Tethering: Rationale, Results, and Revision

Vertebral body tethering is a nonfusion technique for the surgical correction of adolescent idiopathic scoliosis. For skeletally immature patients for whom vertebral body tethering is indicated, it is an alternative option to the gold standard posterior spinal fusion (PSF) and may at least partially preserve motion in instrumented segments of the spine. Benefits of the procedure include the possibility of avoiding the long-term sequelae of PSF such as adjacent segment disease and proximal junctional kyphosis. Recent retrospective case series of vertebral body tethering have shown promising results with correction rates up to 70% but greater variability in outcomes compared with PSF. The complication profile of the procedure also appears to differ from PSF with tether breakage and overcorrection as primary concerns in addition to approach-related complications. Although early outcomes have been promising, additional studies to optimize surgical timing, long-term outcomes, and the possible role of tethering in the more skeletally mature patient are required.

Analysis of risk factors related to the re-fracture of adjacent vertebral body after PKP

BACKGROUND

This study aims to investigate the risk factors of vertebral re-fracture after percutaneous kyphoplasty (PKP) for osteoporosis vertebral compression fracture (OVCF), and to provide reference for clinical prevention.

MATERIAL AND METHODS

A retrospective analysis was performed on 228 OVCF patients admitted on November 6, 2013, solstice, December 14, 2018, which met the inclusion criteria. There were 35 males and 193 females, with a male-to-female ratio of 3:20, and an age of 61-89 years. All patients were treated with PKP surgery with complete clinical data, and the rate of re-fracture was calculated according to whether re-fracture occurred after surgery, divided into the re-fracture group (24 cases) and the non-refracture group (204 cases). May be associated with subsequent fracture factors (gender, age, number of surgical segment vertebral body, whether with degenerative scoliosis, whether to fight osteoporosis) into a single-factor research, then the single-factor analysis was statistically significant risk factors for multiple logistic regression analysis, further defined after PKP holds the vertebral body fracture independent risk factors. Survival analysis was performed using the time of vertebral re-fracture after PKP as the end time of follow-up, the occurrence of re-fracture after PKP as the endpoint event, and the presence or absence of degenerative lateral curvature as a variable factor.

RESULTS

All 228 vertebroplasty patients were followed up for a period of 1.8 to 63.6 months. The mean follow-up time was (28.8 ± 15.6) months, and the re-fracture rate was 10.5%. There were statistically significant differences between the re-fracture group and the non-refracture group in age, number of operative vertebral bodies, whether there was a combination of degenerative scoliosis and whether there was anti-osteoporosis treatment (P < 0.05). The results of univariate logistic regression analysis after excluding the mutual influence of various factors showed that the number of vertebral bodies and the group with lateral curvature might be the risk factors for PKP re-fracture after surgery. The above possible risk factors were included in multiple logistic regression analysis to show whether there were independent risk factors for scoliosis and vertebral re-fracture. Survival analysis showed that the mean survival time was 42.1 months, the P value was 0.00, and the mean 95% confidence interval was (34.4-49.7 months), indicating that the combination of degenerative lateral bending might be related to the occurrence of re-fracture.

CONCLUSIONS

Combined scoliosis is an independent risk factor for re-fracture after OVCF laminoplasty and a possible risk factor for re-fracture after surgery.

Anterior Vertebral Body Tethering for Adolescent Idiopathic Scoliosis: Early Results and Future Directions

Anterior vertebral body tether (AVBT) is a nonfusion surgical procedure for correction of scoliosis in skeletally immature individuals. With US Food and Drug Administration approval in 2019, AVBT technology is spreading and early to midterm reports are being published. Early clinical reports are promising while precise indications, outcomes, complication profiles, and best practices are being established. Patients who are skeletally immature and wish to avoid a fusion surgery may benefit from this procedure. This article highlights the translational science foundation, early to midterm clinical reports, and future directions for this growing technique in pediatric spinal deformity surgery.

Patient-Reported Outcomes Are Equivalent in Patients Who Receive Vertebral Body Tethering Versus Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis

Anterior vertebral body tethering (AVBT), or spinal growth tethering, is an emerging technology that recently received Food and Drug Administration (FDA) approval through a humanitarian device exemption designation to treat idiopathic scoliosis patients with remaining growth. This study compared patients who underwent AVBT with those treated with standard-of-care posterior spinal fusion (PSF) to determine inherent differences in patients and families who seek cutting-edge treatments. The authors reviewed 62 PSF patients from a multicenter registry and 20 AVBT patients from an FDA-approved investigational clinical trial. The authors examined demographics, preoperative clinical and radiographic variables, and health-related quality of life (HRQOL). All included patients preoperatively were classified as Lenke type 1 or 2 with a thoracic curve of 35° to 60°, a lumbar curve less than 35°, and a skeletal maturity score of Risser sign 0 or Sanders bone age of 4 or less. Idiopathic scoliosis patients treated with surgical intervention were primarily White females who were 12 years old. No differences in demographics, clinical variables, and radiographic measures were detected between the PSF and AVBT cohorts. The AVBT group showed more thoracic flexibility on bending radiographs, correcting on average 59% compared with 43% for PSF patients (P=.005). Patients had similar HRQOL total scores and scores across each of the 5 domains of the Scoliosis Research Society Questionnaire Version 22. The percentage of patients scoring below 4.0 within each domain was comparable between cohorts. Scoliosis patients who underwent vertebral tethering at a level of deformity magnitude and maturity similar to those who underwent posterior fusion did not differ at baseline regarding demographics, clinical variables, and HRQOL. [Orthopedics. 2021;44(1):24-28.].

Comparison of Long Segmental Dorsal Stabilization with Complete Versus Restricted Pedicle Screw Cement Augmentation in Unstable Osteoporotic Midthoracic Vertebral Body Fractures: A Biomechanical Study

OBJECTIVE

To compare the construct stability of long-segmental dorsal stabilization in unstable midthoracic osteoporotic fracture situation with complete pedicle screw cement augmentation (ComPSCA) versus restricted pedicle screw cement augmentation (ResPSCA) of the most cranial and caudal pedicle screws.

METHODS

Twelve fresh frozen human cadaveric specimens (Th 4-Th 10) aged 65 years and older were tested in a biomechanical cadaver study. All specimens received a dual-energy X-ray absorption scan and computed tomography scan before testing. Standardized long segmental stabilization was performed. All specimens were matched into pairs. These pairs were randomized into the groups with ComPSCA and ResPSCA. An unstable Th7 fracture was simulated. The maximum load was tested with 6 mm/min until failure or 20 mm had been reached. After testing, a computed tomography scan was performed.

RESULTS

The mean age of the specimens was 87.8 years (range 74-101 years). The mean t score was -3.6 (range -1.2 to -5.3). The mean maximum force in the ResPSCA group was 1600 N (range 1119-1880 N) and 1941 N (1183-3761 N) in the ComPSCA group. No statistically significant differences between both study groups (P = 1.0) could be seen. No signs of screw loosening were visible.

CONCLUSIONS

No statistically significant differences in the maximum loads could be seen. No screw loosening of the non-cemented screws was visible. Thus, the construct stability of long segmental posterior stabilization of an unstable midthoracic fracture using ResPSCA seems to be comparable with ComPSCA under axial compression.

Non-operative management of spinal metastases: A prognostic model for failure

OBJECTIVES

To describe patient-specific characteristics associated with non-operative failure leading to surgery.

PATIENTS AND METHODS

We conducted a retrospective review of patients treated for spinal metastases from 2005 to 2017. We deemed patients as failures if they were treated non-operatively and then received a surgical intervention within one year of starting a non-operative regimen. We used multivariable Poisson regression to identify factors associated with non-operative failure. We conducted internal validation using bootstrapping with 1000 replications.

RESULTS

We identified 1205 patients with spinal metastases, of whom 834 were initially treated non-operatively and constituted the analytic sample. Of these 77 (9%) went on to have surgery within 1-year of presentation and were deemed non-operative treatment failures. We identified vertebral body collapse and/or pathologic fracture (adjusted Risk Ratio [RR] 1.75; 95% Confidence Interval [CI] 1.11, 2.76) and neurologic signs or symptoms at presentation (RR 1.90; 95% CI 1.19, 3.03) as factors independently associated with an increased risk of non-operative failure. Platelet-lymphocyte ratio >155, a marker for inflammatory state, was also associated with an increased risk of failure (RR 2.32; 95% CI 1.15, 4.69). Failure rates among those with 0, 1, 2 or all three of these risk factors were 5%, 7%, 12% and 20%, respectively (p = 0.004).

CONCLUSION

We found that 9% of patients with spinal metastases initially treated non-operatively received surgery within 1-year of commencing care. The likelihood of surgery increased with the number of risk factors. These results can be used in counseling and shared decision making at the time of initial presentation.