Assessing Alignment Using GAP Score and Complications for Pedicle Subtraction Osteotomy Revision Surgeries for Sagittal Deformity in Previously Fused Spines Using a Satellite Rod Technique.

OBJECTIVE: Pedicle subtraction osteotomy (PSO) is a surgical technique to restore lumbar lordosis in patients with rigid sagittal deformity. Herein, we report on outcomes of a surgical technique utilizing a 4-rod PSO with satellite rods. METHODS: A retrospective study was performed for a cohort of patients who underwent 4-rod PSO revision surgery for sagittal deformity. Procedures were performed by one surgeon at 2 different academic centers between 2004-2018. Alignment outcomes and complications specifically for revision surgeries in previously fused spines were assessed. RESULTS: 40 patients underwent PSO with the satellite rod technique (n = 29 at L3, 72.5%; n = 7 at L4, 17.5%). Mean PSO angle was 28.7 ± 7.6°. Two patients (5%) had rod fracture necessitating revision surgery at 32 and 34 months. Three patients (7.5%) developed proximal junctional kyphosis (PJK), but none required revision. No patients developed pseudoarthrosis. Mean preoperative sagittal vertical axis (SVA) was 13.5 ± 7.3 cm, which decreased to 4.8 ± 7.3 cm (P = 0.002) postoperatively. Mean preoperative pelvic incidence-lumbar lordosis (PI-LL) mismatch improved from 35.9 ± 16.6° preoperatively to 11.8 ± 14.6° postoperatively (P < 0.001). Mean preoperative pelvic tilt (PT) improved from 34.7 ± 9.8° preoperatively to 30.1 ± 9.0° (P = 0.026) postoperatively. Mean global alignment and proportion (GAP) score improved from 10 ± 2 preoperatively to 8 ± 2 postoperatively (P < 0.001), which was still considered severely disproportioned. CONCLUSIONS: Rod failure rate after PSO with the 4-rod satellite configuration was low. SVA, PI-LL mismatch, and PT significantly improved for these previously-fused patients. Mean GAP score also improved, but was still considered severely disproportioned, likely due to the inability of PSO to correct low LL or PT in previously-fused spines.

Satellite Rod Fixation around Rod-fracture Area in Revision Surgery after Three-column Osteotomy for Severe Kyphoscoliosis.

OBJECTIVE: Three-column osteotomy (3CO) is considered valuable and increasingly utilized in the surgical treatment of severe spine deformity while associated with high implant-related complications and revision risks. This study aims to evaluate the feasibility and clinical outcomes of satellite rod fixation used around the rod-fracture area in revision surgery due to rod fracture after 3CO. METHODS: Twenty-five patients applying satellite rod fixation in revision surgery from August 2012 to May 2016 were retrospectively reviewed as the SR group. Patients undergoing revision surgery with traditional strategy after 3CO due to rod-fracture were selected as the TR group. Cobb angle, distance between C7 plumb line and center sacral vertical line (C7 PL-CSVL), global kyphosis (GK) and sagittal vertical axis (SVA) were assessed. Patients were required to fulfill the Scoliosis Research Society-22 questionnaire (SRS-22) at pre-revision and the last follow-up. The paired t test was used to analyze the difference among pre-revision, post-revision and last follow-up. RESULTS: There was no statistical difference in terms of age, gender, body mass index (BMI), fusion level at 1st surgery, and follow-up period between SR and TR group (all P > 0.05). The operation time (1.5 ± 0.7 h vs 3.2 ± 0.9 h, P < 0.001) and intraoperative blood loss (178 ± 51 mL vs 324 ± 96 mL, P < 0.001) were significantly higher in the TR group. Patients in both groups obtained obvious deformity correction after revision surgery. For patients in SR group, the coronal Cobb angle significantly improved from 27.9 ± 21.5° at pre-revision to 21.8 ± 16.6° at post-revision (P = 0.034). The C7 PL-CSVL decreased from 22.6 ± 14.3 mm to 21.3 ± 10.9 mm (P = 0.719). Similarly, improvement was attained in post-revision GK (25.8 ± 17.0° vs 20.2 ± 15.1°, P = 0.061). SVA was corrected from 35.6 ± 33.9 mm to 30.8 ± 24.3 mm after revision (P = 0.182). At the last follow-up, no significant correction loss was observed in both coronal and sagittal parameters (all P > 0.05). All patients responded to the SRS-22 questionnaire and all the domains showed improvements in different levels. As compared to the TR group, the SR group had significantly better pain and management satisfaction scores (all P < 0.05). Additionally, there was no reoccurrence of implant failure during follow-up and all patients achieved solid bony fusion in SR group. CONCLUSION: Satellite rod fixation around rod-fracture area is indicated for patients in the requirement of revision surgeries due to rod fracture after 3CO. Compared with traditional revision strategies, revision surgery with satellite rods, if patients are selected adequately, is a simpler procedure with less intraoperative blood loss and shorter operating time.

A Dual-Screw Technique for Vertebral Compression Fractures via Robotic Navigation in the Osteopenic Lumbar Spine: An In-Vitro Biomechanical Analysis.

STUDY DESIGN: Biomechanical cadaveric study. OBJECTIVES: Multi-rod constructs maximize posterior fixation, but most use a single pedicle screw (PS) anchor point to support multiple rods. Robotic navigation allows for insertion of PS and cortical screw (CS) within the same pedicle, providing 4 points of bony fixation per vertebra. Recent studies demonstrated radiographic feasibility for dual-screw constructs for posterior lumbar spinal fixation; however, biomechanical characterization of this technique is lacking. METHODS: Fourteen cadaveric lumbar specimens (L1-L5) were divided into 2 groups (n = 7): PS, and PS + CS. VCF was simulated at L3. Bilateral posterior screws were placed from L2-L4. Load control (±7.5Nm) testing performed in flexion-extension (FE), lateral bending (LB), axial rotation (AR) to measure ROM of: (1) intact; (2) 2-rod construct; (3) 4-rod construct. Static compression testing of 4-rod construct performed at 5 mm/min to measure failure load, axial stiffness. RESULTS: Four-rod construct was more rigid than 2-rod in FE (P < .001), LB (P < .001), AR (P < .001). Screw technique had no significant effect on FE (P = .516), LB (P = .477), or AR (P = .452). PS + CS 4-rod construct was significantly more stable than PS group (P = .032). Stiffness of PS + CS group (445.8 ± 79.3 N/mm) was significantly greater (P = .019) than PS (317.8 ± 79.8 N/mm). Similarly, failure load of PS + CS group (1824.9 ± 352.2 N) was significantly greater (P = .001) than PS (913.4 ± 309.8 N). CONCLUSIONS: Dual-screw, 4-rod construct may be more stable than traditional rod-to-rod connectors, especially in axial rotation. Axial stiffness and ultimate strength of 4-rod, dual-screw construct were significantly greater than rod-to-rod. In this study, 4-rod construct was found to have potential biomechanical benefits of increased strength, stiffness, stability.

Sequential correction using satellite rod for the treatment of severe rigid spinal deformity: a retrospective study of 19 cases.

OBJECTIVES: The purpose of this study was to evaluate the effectiveness of sequential correction using satellite rod in patients with severe rigid spinal deformity undergoing posterior-only PVCR. METHODS: 19 patients with severe rigid spinal deformity who underwent PVCR at our center from January 2014 to December 2019 were reviewed. Radiographic measurements, including major coronal Cobb angle, kyphotic curve angle, coronal and sagittal balance were measured. Clinical results were noted, including the SRS-22 questionnaire, the Oswestry Disability Index score, and complications. RESULTS: Total 19 patients were followed at least 2 years. The mean coronal Cobb angle decreased from 122.7° ± 13.17° to 57.89° ± 8.65° postoperatively, and to 58.42° ± 8.98° at final follow-up. Correction rate is 52.8%. The kyphotic curve angle improved from 102.2° ± 17.05° preoperatively to 39.68° ± 13.67° postoperatively, and to 37.74° ± 12.14° at final follow-up. Correction rate is 61.2%. Compared to preoperative results, apex vertebral translation, ODI and SRS-22 were significantly improved at the final follow-up. CONCLUSIONS: For patients with severe rigid spinal deformities, sequential correction with an auxiliary satellite rod can effectively reduce surgical difficulty and improve correction rate.

Clinical Results of Utilizing the Satellite Rod Technique in Treating Ankylosing Spondylitis Kyphosis.

OBJECTIVE: According to the literature, there are no clinical reports documenting the use of the satellite rod technique in the treatment of ankylosing spondylitis kyphosis. The purpose of this retrospective study was to compare the clinical outcome of patients with ankylosing spondylitis kyphosis who adopted satellite rods versus those who did not. METHODS: Patients with ankylosing spondylitis kyphosis who underwent one or two-level pedicle subtraction osteotomy (PSO) were reviewed, and total of 119 patients (112 males and seven females, average age 39.89 ± 6.61 years) were eligible and included in this present study. Anterior-posterior and lateral full-length spine X-ray films were performed preoperatively and at the two-year follow-up visit. Global kyphosis (GK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), thoracic kyphosis (TK), and osteotomy angle (OA) were measured. The complications of every group of patients were collected. Pre- and postoperative health-related quality of life instruments, including the Bath Ankylosing Spondylitis Functional Index (Basfi) and Scoliosis Research Society outcomes instrument-22 (SRS-22), were recorded. The patients were divided into three groups based on features of their osteotomy including PSO levels and whether the satellite rod technique was applied. Patients who underwent one-level PSO without the satellite rod technique were categorized in the one-level group. Patients who underwent one-level PSO with the satellite rod technique were classified in the satellite rod group. Patients who underwent two-level PSO without the satellite rod technique were included in the two-level group. The paired sample t test was used to compare pre- and postoperative parameters. One-way ANOVA was performed for multiple group comparisons. RESULTS: The average follow-up time is 29.31 ± 3.66 months. The patients' GK were significantly improved from 46.84 ± 20.37 degree to 3.31 ± 15.09 degree. OS achieved through each osteotomy segment of one-level group (39.78 ± 12.29 degree) and satellite rods group (42.23 ± 9.82 degree), was larger than that of two-level group (34.73 ± 7.54 and 28.85 ± 7.26 degree). There was no significant difference between the one-level group and the satellite rod group in achieving the OS. Thirteen patients experienced different complications (10.92%). Three patients experienced rod fracture in the one-level group. There was no rod fracture or screw failure in the satellite rod group or the two-level group. CONCLUSION: The satellite rod technique is also recommended for patients who undergo PSO osteotomy to correct ankylosing spondylitis kyphosis deformities.

Sequential correction using satellite rod for severe thoracic idiopathic scoliosis: an effective method to optimize deformity correction.

OBJECTIVE: The aim of this paper was to compare the radiographic and clinical outcomes between the sequential correction (SC) technique and the traditional 2-rod correction (TC) technique in patients with severe thoracic idiopathic scoliosis (STIS) undergoing posterior-only correction surgery. METHODS: Records of a consecutive series of STIS patients undergoing posterior-only correction surgery between October 2013 and October 2017 with more than 2 years of follow-up were reviewed. The radiographic parameters were assessed preoperatively, postoperatively, and at the last follow-up. Radiographic parameters, operative time, blood loss, and complications were compared between the two groups. RESULTS: A total of 33 patients were included in the SC group, and 21 patients were included in the TC group. There was no significant difference in age, sex, or deformity magnitude (93.6° ± 7.8° vs 89.8° ± 6.6°, p = 0.070) preoperatively between groups. The operation time was shorter in the SC group than in the TC group (251.5 ± 42.8 minutes vs 275.4 ± 39.8 minutes, p = 0.020), while both blood loss (1284.6 ± 483.3 vs 1398.0 ± 558.4 ml, p = 0.432) and number of fused levels (13.1 ± 2.8 vs 13.6 ± 2.4, p = 0.503) were similar between the groups. Compared with the TC group, patients in the SC group had a higher correction rate (55.8% ± 9.2% vs 45.7% ± 8.8%, p < 0.001), less coronal (1.1° ± 0.81° vs 2.9° ± 0.93°, p < 0.001) and sagittal (1.5° ± 0.96° vs 2.1° ± 0.64°, p = 0.015) correction loss at the 2-year follow-up, and a lower incidence of intraoperative pedicle screw pullout (14.3% vs 23.8%, p = 0.026). CONCLUSIONS: The SC technique could significantly and practically reduce the difficulty of rod installation with better deformity correction outcomes than the traditional TC technique. The SC technique was an effective alternative for patients with STIS.

Effects of Revision Rod Position on Spinal Construct Stability in Lumbar Revision Surgery: A Finite Element Study.

Revision surgery (RS) is a necessary surgical intervention in clinical practice to treat spinal instrumentation-related symptomatic complications. Three constructs with different configurations have been applied in RS. One distinguishing characteristic of these configurations is that the revision rods connecting previous segments and revision segments are placed alongside, outside, or inside the previous rods at the level of facetectomy. Whether the position of the revision rod could generate mechanical disparities in revision constructs is unknown. The objective of this study was to assess the influence of the revision rod position on the construct after RS. A validated spinal finite element (FE) model was developed to simulate RS after previous instrumented fusion using a modified dual-rod construct (DRCm), satellite-rod construct (SRC), and cortical bone trajectory construct (CBTC). Thereafter, maximum von Mises stress (VMS) on the annulus fibrosus and cages and the ligament force of the interspinous ligament, supraspinous ligament, and ligamentum flavum under a pure moment load and a follower load in six directions were applied to assess the influence of the revision rod position on the revision construct. An approximately identical overall reducing tendency of VMS was observed among the three constructs. The changing tendency of the maximum VMS on the cages placed at L4-L5 was nearly equal among the three constructs. However, the changing tendency of the maximum VMS on the cage placed at L2-L3 was notable, especially in the CBTC under right bending and left axial rotation. The overall changing tendency of the ligament force in the DRCm, SRC, and CBTC was also approximately equal, while the ligament force of the CBTC was found to be significantly greater than that of the DRCm and SRC at L1-L2. The results indicated that the stiffness associated with the CBTC might be lower than that associated with the DRCm and SRC in RS. The results of the present study indicated that the DRCm, SRC, and CBTC could provide sufficient stabilization in RS. The CBTC was a less rigid construct. Rather than the revision rod position, the method of constructing spinal instrumentation played a role in influencing the biomechanics of revision.

Total en bloc spondylectomy combined with the satellite rod technique for spinal tumors.

BACKGROUND: Instrumentation failure (IF) is a common complication after total en bloc spondylectomy (TES) in spinal tumors. This study aims to evaluate the clinical outcomes of TES combined with the satellite rod technique for the treatment of primary and metastatic spinal tumors. METHODS: The clinical data of 15 consecutively treated patients with spinal tumors who underwent TES combined with the satellite rod technique by a single posterior approach from June 2015 to September 2018 were analyzed retrospectively. Radiographic parameters including the local kyphotic angle (LKA), anterior vertebral height (AVH), posterior vertebral height (PVH), and intervertebral titanium mesh cage height (ITMCH) were assessed preoperatively, postoperatively, and at the final follow-up. The visual analog scale (VAS), Oswestry Disability Index (ODI), and American Spinal Injury Association (ASIA) scale were used to assess quality of life and neurological function. The operative duration, volume of blood loss, and complications were also recorded. RESULTS: The mean operation time and volume of blood loss were 361.7 min and 2816.7 mL, respectively. During an average follow-up of 31.1 months, 2 patients died of tumor recurrence and multiple organ metastases, while recurrence was not found in any other patients. Solid fusion was achieved in all but one patient, and no implant-related complications occurred during the follow-up. The VAS, ODI, and ASIA scores significantly improved from before to after surgery (P < 0.05). The LKA, AVH, and PVH significantly improved from before to immediately after surgery and to the final follow-up (P < 0.05), and the postoperative and final follow-up values did not significantly differ (P > 0.05). CONCLUSIONS: TES combined with the satellite rod technique can yield strong three-dimensional fixation and reduce the occurrence of rod breakage, thereby improving the long-term quality of life of patients with spinal tumors.

Assessing the unique characteristics associated with surgical treatment of dystrophic lumbar scoliosis secondary to neurofibromatosis type 1: a single-center experience of more than 10 years.

OBJECTIVE: Dystrophic lumbar scoliosis secondary to neurofibromatosis type 1 (DLS-NF1) may present an atypical, unique curve pattern associated with a high incidence of coronal imbalance and regional kyphosis. Early surgical intervention is complicated and risky but necessary. The present study aimed to assess the unique characteristics associated with the surgical treatment of DLS-NF1. METHODS: Thirty-nine consecutive patients with DLS-NF1 treated surgically at a mean age of 14.4 ± 3.9 years were retrospectively reviewed. Patients were stratified into three types according to the coronal balance classification: type A (C7 translation < 30 mm), 22 patients; type B (concave C7 translation ≥ 30 mm), 0 patients; and type C (convex C7 translation ≥ 30 mm), 17 patients. Types B and C were considered to be coronal imbalance. The diversity of surgical strategies, the outcomes, and the related complications were analyzed. RESULTS: The posterior-only approach accounted for 79.5% in total; the remaining 20.5% of patients received either additional anterior supplemental bone grafting (12.8%) to strengthen the fixation or convex growth arrest (7.7%) to reduce growth asymmetry. The lower instrumented vertebra (LIV) being L5 accounted for the largest share (41%), followed by L4 and above (35.9%), the sacrum (15.4%), and the pelvis (7.7%). Type C coronal imbalance was found in 23 patients (59%) postoperatively, and the incidence was significantly higher in the preoperative type C group (14/17 type C vs 9/22 type A, p = 0.020). All the patients with postoperative coronal imbalance showed ameliorative transition to type A at the last visit. The rate of screw malposition was 30.5%, including 9.9% breached medially and 20.6% breached laterally, although no serious neurological impairment occurred. The incidence of rod breakage was 16.1% (5/31) and 0% in patients with the posterior-only and combined approaches, respectively. Four revisions with satellite rods and 1 revision with removal of iliac screw for penetration into the hip joint were performed. CONCLUSIONS: Surgical strategies for DLS-NF1 were diverse across a range of arthrodesis and surgical approaches, being crucially determined by the location and the severity of dystrophic changes. The LIV being L5 or lower involving the lumbosacral region and pelvis was not rare. Additional posterior satellite rods or supplementary anterior fusion is necessary in cases with insufficient apical screw density. Despite a high incidence of postoperative coronal imbalance, improvement of coronal balance was frequently confirmed during follow-up. Neurological impairment was scarce despite the higher rate of screw malposition.

[Efficacy of sequential correction based on satellite rod techniquein degenerative scoliosis with B-type coronal imbalance].

Objective: To evaluate the radiographic and clinical outcomes of sequential correction based on satellite rod technique in degenerative scoliosis (DS) with B-type coronal imbalance, and to investigate the efficacy of sequential correction in this cohort. Methods: Twenty-one DS patients with B-type coronal imbalance applying sequential correction from December 2015 to July 2017 in Nanjing Drum Tower Hospital were retrospectively reviewed. There were 4 males and 17 females in this group, the average age was (63±8) years. The coronal parameters including Cobb angle of main curve and distance between C(7) plumb line and center sacral vertical line (C(7)PL-CSVL), as well as sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were assessed pre-operatively, post-operatively and at the last follow-up. The Scoliosis Research Society-22 (SRS-22) questionnaire was fulfilled before the operation and at each follow-up to evaluate the quality of life. Paired t test was performed for statistical analysis. Results: The patients were followed-up for (20±8) months. The post-operative Cobb angle of main curve was significantly improved from 52°±12° to 19°±7° (t=13.886, P<0.01), and it was 19°±8° at the last follow-up and no significant correction loss was attained (t=1.101, P=0.284). The values of C(7)PL-CSVL before the operation, after the operation and at the final follow-up were (46±11) mm, (12±7) mm and (12±7) mm, respectively; significant post-operative improvement achieved (t=19.718, P<0.01) while there was no correction loss at last follow-up (t=-1.393, P=0.179). After sequential correction, 20 patients (95.2%) improved to A-type coronal imbalance while 1 patient (4.8%) remained with B-type coronal imbalance. Significant post-operative improvements were found in terms of GK and SVA and no significant correction loss was found during follow-up. The scores of pain and self-image showed significant improvement at the last follow-up (t=8.706, 3.104, both P<0.01). In addition, there was no implant failure during follow-up. Conclusion: The sequential correction based on satellite rod technique in DS patients with B-type coronal imbalance corrects the deformity, relieves the clinical symptoms, improves the quality of life, and decreases the rates of post-operative coronal imbalance as well as implant-related complications.

[SRS-Schwab grade â £ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis].

Objective: To evaluate the effectiveness of SRS-Schwab grade Ⅳ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis. Methods: Between April 2013 and August 2016, 20 cases of thoracolumbar old osteoporotic fracture with severe kyphosis were treated with SRS-Schwab grade Ⅳ osteotomy combined with satellite rod. All the patients were females, aged 49-71 years (mean, 54.8 years). The disease duration was 6-28 months with an average of 14 months. The T value of bone density was -4.4 to -1.8 (mean, -2.8). The preoperative Cobb angle was (43.0±11.3)°. The vertebral compression fracture segment was T 12 in 9 cases, L 1 in 8 cases, and L 2 in 3 cases. Preoperative spinal cord function was evaluated by Frankel classification; there were 5 cases of grade D and 15 cases of grade E. The operation time, intraoperative blood loss, and perioperative complication were recorded. The Cobb angle for kyphosis and sagittal vertical axis (SVA) were recorded beforeoperation, at 3 months after operation, and at last follow-up. Oswestry disability index (ODI) was used to evaluate the effectiveness before operation and at last follow-up, and the evaluation indicators included pain degree, daily life self-care ability, extracting, walking, sitting, standing, sleeping, social activities, and traveling. Results: The operation time was 180-314 minutes (mean, 226 minutes). The intraoperative blood loss was 390-1 800 mL (mean, 750 mL). All the incisions healed by first intension without incision infection. Twenty patients were followed up 24-52 months, with an average of 30.9 months. During the follow-up period, no significant complication such as correction loss, nail breakage, rod breakage, pseudoarthrosis formation, or proximal and distal junctional kyphosis occurred. All patients were able to walk upright after operation, and the pain relieved significantly at 6 months after operation. Bone fusion achieved at 12 months after operation. The Frankel grade of nerve function improved from grade D to grade E at last follow-up in 5 patients with nerve damage before operation. At last follow-up, the indicator scores of ODI significantly improved when compared with preoperative values ( P<0.05). Cobb angle significantly improved at 3 months after operation and at last follow-up ( P<0.05) when compared with preoperative one, but there was no significant difference in the Cobb angles between 3 months after operation and last follow-up ( P>0.05). There was no significant difference in SVA between pre- and post-operation ( P>0.05). Conclusion: SRS-Schwab grade Ⅳ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis is effective in achieving satisfactory clinical outcomes, as well as maintaining correction of kyphosis.

SRS-Schwab grade Ⅳ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis / 中国修复重建外科杂志

Objective: To evaluate the effectiveness of SRS-Schwab grade Ⅳ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis. Methods: Between April 2013 and August 2016, 20 cases of thoracolumbar old osteoporotic fracture with severe kyphosis were treated with SRS-Schwab grade Ⅳ osteotomy combined with satellite rod. All the patients were females, aged 49-71 years (mean, 54.8 years). The disease duration was 6-28 months with an average of 14 months. The T value of bone density was -4.4 to -1.8 (mean, -2.8). The preoperative Cobb angle was (43.0±11.3)°. The vertebral compression fracture segment was T 12 in 9 cases, L 1 in 8 cases, and L 2 in 3 cases. Preoperative spinal cord function was evaluated by Frankel classification; there were 5 cases of grade D and 15 cases of grade E. The operation time, intraoperative blood loss, and perioperative complication were recorded. The Cobb angle for kyphosis and sagittal vertical axis (SVA) were recorded beforeoperation, at 3 months after operation, and at last follow-up. Oswestry disability index (ODI) was used to evaluate the effectiveness before operation and at last follow-up, and the evaluation indicators included pain degree, daily life self-care ability, extracting, walking, sitting, standing, sleeping, social activities, and traveling. Results: The operation time was 180-314 minutes (mean, 226 minutes). The intraoperative blood loss was 390-1 800 mL (mean, 750 mL). All the incisions healed by first intension without incision infection. Twenty patients were followed up 24-52 months, with an average of 30.9 months. During the follow-up period, no significant complication such as correction loss, nail breakage, rod breakage, pseudoarthrosis formation, or proximal and distal junctional kyphosis occurred. All patients were able to walk upright after operation, and the pain relieved significantly at 6 months after operation. Bone fusion achieved at 12 months after operation. The Frankel grade of nerve function improved from grade D to grade E at last follow-up in 5 patients with nerve damage before operation. At last follow-up, the indicator scores of ODI significantly improved when compared with preoperative values ( P0.05). There was no significant difference in SVA between pre- and post-operation ( P>0.05). Conclusion: SRS-Schwab grade Ⅳ osteotomy combined with satellite rod for thoracolumbar old osteoporotic fracture with severe kyphosis is effective in achieving satisfactory clinical outcomes, as well as maintaining correction of kyphosis.

Biomechanical advantages of supplemental accessory and satellite rods with and without interbody cages implantation for the stabilization of pedicle subtraction osteotomy.

PURPOSE: To investigate the effect of anterior interbody cages, accessory and satellite rods usage on primary stability and rod strains for PSO stabilization. METHODS: Seven human cadaveric spine segments (T12-S1) underwent PSO at L4 with posterior fixation from L2 to S1. In vitro flexibility tests were performed under pure moments in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) to determine the range of motion, while measuring the strains on the primary rods with strain gauge rosettes. Six constructs with 2, 3 and 4 rods, with and without interbody cages implantation adjacent to the PSO site, were compared. RESULTS: All constructs had comparable effects in reducing spine kinematics compared to the intact condition (- 94% in FE and LB; - 80% in AR). Supplementation of 2 rods with lateral accessory rods (4 rods) was the most effective strategy in minimizing primary rod strains, particularly when coupled to cages (p ≤ 0.005; - 50% in FE, - 42% in AR and - 11% in LB); even without cages, the strains were significantly reduced (p ≤ 0.009; - 26%, - 37%, - 9%). The addition of a central satellite rod with laminar hooks (3 rods) effectively reduced rod strains in FE (p ≤ 0.005; - 30%) only in combination with cages. CONCLUSIONS: The study supports the current clinical practice providing a strong biomechanical rationale to recommend 4-rod constructs based on accessory rods combined with cages adjacent to PSO site. Although weaker, the usage of accessory rods without cages and of a central satellite rod with hooks in combination with interbody spacers may also be justified. These slides can be retrieved under Electronic Supplementary Material.

Posterior Double Vertebral Column Resections Combined with Satellite Rod Technique to Correct Severe Congenital Angular Kyphosis.

This paper presents a highly challenging technique involving posterior double vertebral column resections (VCRs) and satellite rods placement. This was a young adult case with severe angular thoracolumbar kyphosis of 101 degrees, secondary to anterior segmentation failure from T11 to L1 . There were hemivertebrae at T11 and T12 , and a wedged vertebra at L1 . He received double VCRs at T12 and T11 and instrumented fusion from T6 to L4 via a posterior only approach. Autologous grafts and a cage were placed between the bony surfaces of the osteotomy gap. Once closure of osteotomy was achieved, bilateral permanent CoCr rods were placed with addition of satellite rods. Postoperative X-ray demonstrated marked correction of kyphosis. On the 10(th) days after surgery, the patient was able to walk without assistance. In conclusion, double VCRs are effective to correct severe angular kyphosis, and addition of satellite rods may be imperative to enhance instrumentation strength and thus prevent correction loss.