The incidence of reoperation for pseudarthrosis after cervical spine surgery.

INTRODUCTION: Pseudarthrosis after cervical spine surgery represents an underreported and challenging complication. Using a large multi-center surgical database, we sought to: (1) report the incidence of cervical pseudarthrosis, (2) evaluate changes in rates of cervical pseudarthrosis, and (3) describe risk factors for suboptimal outcomes after cervical pseudarthrosis surgery. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2019 was used. The primary outcome was occurrence of a cervical fusion procedure with a prior diagnosis of pseudarthrosis. Fusion for pseudarthrosis was divided into anterior and posterior approaches. Post-operative complications were classified as major or minor. Prolonged LOS was defined as exceeding the 75th percentile for total hospital stay. RESULTS: A total of 780 patients underwent cervical fusion for pseudarthrosis, and a significant increase in rates of surgery for pseudarthrosis was seen (0.25-1.2%, p < 0.001). The majority of cervical pseudarthrosis was treated with a posterior approach (66.5%). Postoperatively, 38 (4.9%) patients suffered a complication and 247 (31.7%) had a prolonged LOS. The three strongest risk factors for complications and extended LOS were > 10% weight loss preoperatively, congestive heart failure, and pre-operative bleeding disorder. CONCLUSION: Results from a large multi-center national database revealed that surgery to treat cervical pseudarthrosis has increased from 2012 to 2019. Most pseudarthrosis was treated with a posterior approach. Reoperation to treat cervical pseudarthrosis carried risk, with 5% having complications and 32% having an extended LOS. These results lay the groundwork for a future prospective study to discern the true incidence of cervical pseudarthrosis and how to best avoid its occurrence.

An evaluation of fusion status following lumbar fusion surgery utilizing multi-planar computed tomography.

PURPOSE: To report the rate of fusion in a sample of patients undergoing lumbar fusion surgery and assess interrater reliability of computed tomography (CT)-based parameters for the assessment of fusion. METHODS: All adult patients who underwent lumbar fusion surgery from 2017 to 2021 were retrospectively identified. Patient demographics and surgical characteristics were collected through chart review of the electronic medical records. CT scans were reviewed independently by two attending spine surgeons and two spine fellows. Fusion was defined as evidence of bone bridging in any one of (1) posterolateral gutters, (2) facets, or (3) interbody (when applicable) on any CT views. Evidence of screw haloing was indicative of nonunion. Interrater reliability was determined using cohen's kappa. Afterwards, a consensus agreement for each component of fusion was reached between participants. RESULTS: The overall fusion rate among all procedures was 63/69 (91.3%). Overall 22/25 (88.0%) TLIF, 16/19 (84.2%) PLDF, 3/3 (100%) LLIF, and 22/22 (100%) circumferential fusions experienced a successful fusion. Interrater reliability was good for interbody fusion (k = 0.734) and moderate for all other measures (k = 0.561 for posterolateral fusion; k = 0.471 for facet fusion; k = 0.458 for screw haloing). Overall, interrater reliability as to whether a patient had a fusion or nonunion was moderate (k = 0.510). CONCLUSION: There was only moderate interrater reliability across most radiographic measures used in assessing lumbar fusion status. Reliability was highest when evaluating the presence of interbody fusion. The majority of fusions occurred across the facet joints.

Spinopelvic fixation failure in the adult spinal deformity population: systematic review and meta-analysis.

INTRODUCTION: Despite modern fixation techniques, spinopelvic fixation failure (SPFF) after adult spinal deformity (ASD) surgery ranges from 4.5 to 38.0%, with approximately 50% requiring reoperation. Compared to other well-studied complications after ASD surgery, less is known about the incidence and predictors of SPFF. AIMS/OBJECTIVES: Given the high rates of SPFF and reoperation needed to treat it, the purpose of this systematic review and meta-analysis was to report the incidence and failure mechanisms of SPF after ASD surgery. MATERIALS/METHODS: The literature search was executed across four databases: Medline via PubMed and Ovid, SPORTDiscus via EBSCO, Cochrane Library via Wiley, and Scopus. Study inclusion criteria were patients undergoing ASD surgery with spinopelvic instrumentation, report rates of SPFF and type of failure mechanism, patients over 18 years of age, minimum 1-year follow-up, and cohort or case-control studies. From each study, we collected general demographic information (age, gender, and body mass index), primary/revision, type of ASD, and mode of failure (screw loosening, rod breakage, pseudarthrosis, screw failure, SI joint pain, screw protrusion, set plug dislodgment, and sacral fracture) and recorded the overall rate of SPF as well as failure rate for each type. For the assessment of failure rate, we required a minimum of 12 months follow-up with radiographic assessment. RESULTS: Of 206 studies queried, 14 met inclusion criteria comprising 3570 ASD patients who underwent ASD surgery with pelvic instrumentation (mean age 65.5 ± 3.6 years). The mean SPFF rate was 22.1% (range 3-41%). Stratification for type of failure resulted in a mean SPFF rate of 23.3% for the pseudarthrosis group; 16.5% for the rod fracture group; 13.5% for the iliac screw loosening group; 7.3% for the SIJ pain group; 6.1% for the iliac screw group; 3.6% for the set plug dislodgement group; 1.1% for the sacral fracture group; and 1% for the iliac screw prominence group. CONCLUSION: The aggregate rate of SPFF after ASD surgery is 22.1%. The most common mechanisms of failure were pseudarthrosis, rod fracture, and iliac screw loosening. Studies of SPFF remain heterogeneous, and a consistent definition of what constitutes SPFF is needed. This study may enable surgeons to provide patient specific constructs with pelvic fixation constructs to minimize this risk of failure.

Pseudarthrosis risk factors in lumbar fusion: a systematic review and meta-analysis.

This study presents a systematic literature review and meta-analysis of pseudarthrosis risk factors following lumbar fusion procedures. The odds ratio (OR) and 95% confidence interval (95% CI) were used for outcome measurements. The objective of this study was to identify the independent risk factors for pseudarthrosis after lumbar spinal fusion, which is crucial for mitigating morbidity and reoperation. Systematic searches in PubMed, Embase, and Scopus (1990-July 2021) were conducted using specific terms. The inclusion criteria included prospective and retrospective cohorts and case‒control series reporting ORs with 95% CIs from multivariate analysis. The quality assessment utilized the Newcastle-Ottawa scale. Meta-analysis, employing OR and 95% CI, assessed pseudarthrosis risk factors in lumbar fusion surgery, depicted in a forest plot. Of the 568 abstracts identified, 12 met the inclusion criteria (9 retrospective, 2006-2021). The 17 risk factors were categorized into clinical, radiographic, surgical, and bone turnover marker factors. The meta-analysis highlighted two significant clinical risk factors: age (95% CI 1.02-1.11; p = 0.005) and smoking (95% CI 1.68-5.44; p = 0.0002). The sole significant surgical risk factor was the number of fused levels (pooled OR 1.35; 95% CI 1.17-1.55; p < 0.0001). This study identified 17 risk factors for pseudarthrosis after lumbar fusion surgery, emphasizing age, smoking status, and the number of fusion levels. Prospective studies are warranted to explore additional risk factors and assess the impact of surgery and graft type.

Volumetric evaluation of osteotomy gap following mandibular bilateral sagittal split osteotomy using a novel semi-automated approach: a pilot study.

OBJECTIVES: To establish an analysis pipeline for the volumetric evaluation of the osteotomy site after bilateral sagittal split osteotomy (BSSO). PATIENTS AND METHODS: Cone-beam computed tomography (CBCT) was performed before, directly after BSSO, and 6-12 months after surgery. Image segmentations of each osteotomy gap data set were performed manually by four physicians and were compared to a semi-automatic segmentation approach. RESULTS: Five patients with a total of ten osteotomy gaps were included. The mean interclass correlation coefficient (ICC) of individual patients was 0.782 and the standard deviation 0.080 when using the manual segmentation approach. However, the mean ICC of the evaluation of anatomical sites and time points separately was 0.214, suggesting a large range of deviation within the manual segmentation of each rater. The standard deviation was 0.355, further highlighting the extent of the variation. In contrast, the semi-automatic approach had a mean ICC of 0.491 and a standard deviation of 0.365, which suggests a relatively higher agreement among the operators compared to the manual segmentation approach. Furthermore, the volume of the osteotomy gap in the semi-automatic approach showed the same tendency in every site as the manual segmentation approach, but with less deviation. CONCLUSION: The semi-automatic approach developed in the present study proved to be valid as a standardised method with high repeatability. Such image analysis methods could help to quantify the progression of bone healing after BSSO and beyond, eventually facilitating the earlier identification of patients with retarded healing.

Trans-sacral interbody fixation in long fusions to the sacrum for adult spinal deformity: complications and fusion rates at minimum two years follow-up.

PURPOSE: This study aims to investigate the fusion rate and complications associated with trans-sacral interbody fusion (TSIF) in long fusions to the sacrum for adult spinal deformity (ASD) over a two year follow-up period. Potential predictor variables associated with pseudarthrosis were also examined. METHODS: A retrospective clinical review was conducted on a consecutive series of ASD patients who underwent long fusions to the sacrum, with TSIF performed as a same-day or staged procedure. Patient demographics, bone mineral density, operative details, perioperative and late complications, and fusion rates were reviewed. Univariate analysis was used to identify the risk factors associated with pseudarthrosis. RESULTS: The study included 43 patients with an average age of 55.3 ± 8.9 years. The perioperative complication rate was 28%, with 12% of the complications directly related to TSIF. The late complication rate was 33%, with 16% related to TSIF. The most common complications were pseudarthrosis (14%) and postoperative ileus (7%). The overall radiographic fusion rate at two years was 86%. Univariate analysis revealed that revision surgery was significantly associated with pseudarthrosis (p = 0.027). Over the follow-up period, patients who underwent TSIF during long posterior fusions to the sacrum showed improvement in overall SRS scores, ODI scores, and SF-36 physical health and mental health (p < 0.05). CONCLUSION: TSIF is a relatively safe and minimally invasive method for achieving interbody fusion at the lumbosacral junction in the treatment of ASD, with acceptable fusion rates and a low complication rate. However, TSIF is not recommended for revision reconstruction in ASD.

Surgical treatment of fracture sequelae of the proximal humerus according to a pathology-based modification of the Boileau classification results in improved clinical outcome after shoulder arthroplasty.

BACKGROUND: Fracture sequelae of the proximal humerus were classified by Boileau into four types. Since there are pathomorphological differences and specific characteristics within the four types, we have developed a subclassification. For elderly patients, shoulder arthroplasty is mostly recommended. Based on the available literature and clinical trial results, a subclassification could be created that suggests a specific therapy for each subgroup. The aim of this study was to evaluate the endoprosthetic therapy according to the proposed subclassification and to provide an overview of the clinical and radiological results after endoprosthetic treatment of proximal humerus fracture sequelae. METHODS: Patients with fracture sequelae of the proximal humerus who underwent arthroplasty according to the suggestion of the subclassification were included. Minimum time to follow-up was twelve months. General condition and several specific shoulder scores as the Constant-Murley Score (CS) were recorded at the follow-up examination. Complication and revision rates were analyzed. RESULTS: In total, 59 patients (72.6 ± 10.0 years, 47 females, 12 males) were included. Mean follow-up time was 31.3 ± 17.0 months. Reverse shoulder arthroplasty was performed in 49 patients and anatomic shoulder arthroplasty was performed in ten patients. The CS increased by 47.3 points from preoperative (15.0) to postoperative (62.3). Good or very good clinical results were seen in 61% of the patients. Complications were observed in twelve (20%) patients and revision surgery was performed in nine (15%) patients. CONCLUSION: Due to of the variety of fracture sequelae of the proximal humerus, a modification of the Boileau classification seems necessary. This study shows that endoprosthetic treatment for fracture sequelae can significantly improve the shoulder function in elderly patients. Good clinical results can be achieved with a comparatively low revision rate following the treatment suggestions of the proposed subclassification of the Boileau classification. LEVEL OF EVIDENCE IV: Case series.

L1-pelvic angle: a convenient measurement to attain optimal deformity correction.

PURPOSE: (1) Evaluate the associations between L1-pelvic angle (L1PA) and both sagittal vertical axis (SVA) and T1-pelvic angle (T1PA), and (2) assess the clinical impact of L1PA. METHODS: A single-institution retrospective cohort study was undertaken for patients undergoing adult spinal deformity (ASD) surgery from 2013 to 2017. Ideal L1PA was defined as (0.5xPelvic Incidence)-21. Pearson correlation was performed to compare L1PA, SVA, and T1PA. Univariate/multivariate regression was performed to assess the effect of L1PA on mechanical complications, controlling for age, BMI, and postoperative pelvic incidence-lumbar lordosis mismatch (PI/LL). Due to the overlapping nature of patients with pseudarthrosis and rod fracture, these patients were analyzed together. RESULTS: A total of 145 patients were included. Mean preoperative L1PA, SVA, and T1PA were 15.5 ± 8.9°, 90.7 ± 66.8 mm, and 27.1 ± 13.0°, respectively. Mean postoperative L1PA, SVA, and T1PA were 15.0 ± 8.9°, 66.7 ± 52.8 mm, and 22.3 ± 11.1°, respectively. Thirty-six (24.8%) patients achieved ideal L1PA. Though the correlation was modest, preoperative L1PA was linearly correlated with preoperative SVA (r2 = 0.16, r = 0.40, 95%CI = 0.22-0.60, p < 0.001) and T1PA (r2 = 0.41, r = 0.62, 95%CI = 0.46-0.76, p < 0.001). Postoperative L1PA was linearly correlated with postoperative SVA (r2 = 0.12, r = 0.37, 95%CI = 0.18-0.56, p < 0.001) and T1PA (r2 = 0.40, r = 0.62, 95%CI = 0.45-0.74, p < 0.001). Achieving ideal L1PA ± 5° was associated with a decreased risk of rod fracture/pseudarthrosis on univariate and multivariate regression (OR = 0.33, 95%CI = 0.12-0.86, p = 0.024). No association between achieving ideal L1PA and patient-reported outcomes was observed. CONCLUSION: L1PA was modestly correlated with SVA and T1PA, and achieving ideal L1PA was associated with lower rates of rod fracture/pseudarthrosis. Future studies are warranted to better define the clinical implications of achieving a normal L1PA. LEVEL OF EVIDENCE: III.

Adult spinal deformity patients revised for pseudarthrosis have comparable two-year outcomes to those not undergoing any revision surgery.

PURPOSE: This study aimed to evaluate whether adult spinal deformity patients undergoing revision for symptomatic pseudarthrosis have comparable two-year outcomes as patients who do not experience pseudarthrosis. METHODS: Patients whose indexed procedure was revision for pseudarthrosis (pseudo) were compared with patients who underwent a primary procedure and did not have pseudarthrosis by 2Y post-op (non-pseudo). Patients were propensity-matched (PSM) based on baseline (BL) sagittal alignment, specifically C7SVA and CrSVA-Hip. Key outcomes were 2Y PROs (SRS and ODI) and reoperation. All patients had a minimum follow-up period of two years. RESULTS: A total of 224 patients with min 2-year FU were included (pseudo = 42, non-pseudo = 182). Compared to non-pseudo, pseudo-patients were more often female (P = 0.0018) and had worse BL sagittal alignment, including T1PA (P = 0.02], C2-C7 SVA [P = 0.0002], and CrSVA-Hip [P = 0.004]. After 37 PSM pairs were generated, there was no significant difference in demographics, BL and 2Y alignment, or operative/procedural variables. PSM pairs did not report any significantly different PROs at BL. Consistently, at 2Y, there were no significant differences in PROs, including SRS function [3.9(0.2) vs 3.7(0.2), P = 0.44], pain [4.0 (0.2) vs. 3.57 (0.2), P = 0.12], and ODI [25.7 (5.2) vs 27.7 (3.7), P = 0.76]. There were no differences in 1Y (10.8% vs 10.8%, P > 0.99) and 2Y (13.2% vs 15.8%, P = 0.64) reoperation, PJK rate (2.6% vs 10.5%, P = 0.62), or implant failure (2.6% vs 10.5%, P = 0.37). Notably, only 2 patients (5.4%) had recurrent pseudarthrosis following revision. Kaplan-Meier curves indicated that patients undergoing intervention for pseudarthrosis had comparable overall reoperation-free survival (log-rank test, χ2 = 0.1975 and P = 0.66). CONCLUSIONS: Patients undergoing revision for pseudarthrosis have comparable PROs and clinical outcomes as patients who never experienced pseudarthrosis. Recurrence of symptomatic pseudarthrosis was infrequent.

Medial augmentation plating of aseptic distal femoral nonunions.

BACKGROUND: Distal femur nonunions are well-recognized contributors to persistent functional disability, with limited data regarding their treatment options. In the current study, we asked whether additional medial augmentation plating is a feasible treatment option for patients with aseptic distal femoral nonunion and intact lateral implants. METHODS: We conducted a single-center, retrospective study including 20 patients treated for aseptic distal femoral nonunion between 2002 and 2017. The treatment procedure included a medial approach to the distal femur, debridement of the nonunion site, bone grafting and medial augmentation plating utilizing a large-fragment titanium plate. Outcome measures were bone-related and functional results, measured by the Hospital for Special Surgery Knee Rating Scale (HSS) and the German Short Musculoskeletal Function Assessment questionnaire (SMFA-D). RESULTS: Eighteen of 20 nonunions showed osseous healing at 8.16 ± 5.23 (range: 3-21) months after augmentation plating. Regarding functional results, the mean HSS score was 74.17 ± 11.12 (range: 57-87). The mean SMFA-D functional index was 47.38 ± 16.78 (range 25.74-71.32) at the last follow-up. Index procedure-associated complications included two cases of persistent nonunion and one case of infection. CONCLUSIONS: According to the assessed outcome measures, augmentation plating is a feasible treatment option, with a high proportion of patients achieving bony union and good functional outcomes and a few patients experiencing complications.

Pseudarthrosis after four-level anterior cervical discectomy and fusion without posterior fixation.

OBJECTIVE: Fusion rates and long-term outcomes are well established for anterior cervical discectomy and fusion (ACDF) of 3 levels or fewer, but there is a paucity of similar data on 4-level fusions. The authors evaluated long-term fusion rates and clinical outcomes after 4-level ACDF without supplemental posterior instrumentation. METHODS: The authors retrospectively reviewed patients who underwent 4-level ACDF at a single institution with at least 1-year of radiological follow-up. Fusion was determined by measuring change in interspinous distance at each segment on dynamic radiographs or by the presence of bridging bone on CT scans at minimum 1-year follow-up. Clinical outcomes were assessed using Neck Disability Index and Short Form-36. RESULTS: A total of 63 patients (252 levels) met the inclusion criteria for the study, with a mean follow-up of 2.6 years. Complete radiographic fusion at all 4 levels was observed in 26 patients (41.3%). Of the 37 patients (58.7%) with radiographic pseudarthrosis, there was a mean of 1.35 nonfused levels. The fusion rate per level, however, was 80.2% (202/252 levels). The most common level demonstrating nonunion was the distal segment (C6-7), showing pseudarthrosis in 29 patients (46.8%), followed by the most proximal segment (C3-4) demonstrating nonunion in 9 patients (14.5%). The mean improvement in Neck Disability Index and Short Form-36 was 15.7 (p < 0.01) and 5.8 (p = 0.14), respectively, with improvement in both scores surpassing the minimum clinically important difference. One patient (1.6%) required revision surgery for symptomatic pseudarthrosis, and 5 patients (7.9%) underwent revision for symptomatic adjacent-segment disease. Patient-reported outcomes results are limited by the low rate of 1-year follow-up (50.8%), whereas reoperation data were available for all 63 patients. CONCLUSIONS: More than half of patients undergoing 4-level ACDF without posterior fixation demonstrated pseudarthrosis of at least 1 level-most commonly the distal C6-7 level. One patient required revision for symptomatic pseudarthrosis. Patient-reported outcomes showed significant improvements at 1-year follow-up, but clinical follow-up was limited. This is the largest series to date to evaluate fusion outcomes in 4-level ACDF.

Treatment of sacroiliac joint laxity-induced coronal imbalance with the kickstand rod technique.

BACKGROUND: Considerations of the sacroiliac joint (SIJ) and its role in causing lower back and limb pain have taken a secondary role ever since Mixter and Barr's hallmark article in 1934 on the herniated nucleus pulposus. However, recent literature has highlighted the contribution of sacroiliac joint degeneration in the development of failed back surgery syndrome (FBSS), especially in patients undergoing lumbar or lumbosacral spinal fusion surgeries. Many reports have studied the anatomy, physiology, and clinical significance of the sacroiliac joint, but none have linked its dysfunction with other spinal deformities. CASE DESCRIPTION: A 63-year-old female with a history of multiple complex instrumented spinal fusions presented to our institution with progressive leftward coronal imbalance despite successful arthrodesis from T3 through S1. She was initially treated with decompression and reimplantation, but adjacent segment disease at the SIJ led to laxity, distal failure, and a worsening coronal deformity. A mechanical fall after her decompression surgery led to a dramatically increased coronal imbalance, which was ultimately treated using Lenke's kickstand rod technique. At 3.5 years follow up, the patient's coronal balance remains stable. CONCLUSION: Few studies have related SIJ degeneration and laxity with spinal deformity. Our case describes SIJ degeneration that evolved to joint laxity, which ultimately produced a leftward coronal imbalance according to the adjacent segment disease mechanism. Additionally, we describe the use of a kickstand rod to effectively correct the coronal imbalance, reduce pain levels, promote SIJ arthrodesis, and prevent further SIJ-related issues without significant complications over 3 years post-operation.

Bone health in RASopathies.

The RASopathies are a group of disorders due to pathogenic variants in genes involved in the Ras/MAPK pathway, many of which have overlapping clinical features (e.g., neurofibromatosis type 1, Costello syndrome, cardiofaciocutaneous syndrome and Noonan syndrome) including musculoskeletal manifestations. Osteopenia and osteoporosis are reported in many of the RASopathies suggesting a shared pathogenesis. Even though osteopenia and osteoporosis are often detected and fractures have been reported, the clinical impact of bone mineralization defects on the skeleton of the various syndromes is poorly understood. Further knowledge of the role of the Ras/MAPK pathway on the bone cellular function, and more detailed musculoskeletal phenotyping will be critical in helping to develop therapies to improve bone health in the RASopathies.

The recurrent homozygous translation start site variant in CCDC134 in an individual with severe osteogenesis imperfecta of non-Morrocan ancestry.

Osteogenesis imperfecta (OI) is a rare low-bone mass skeletal Mendelian disorder characterized by bone fragility leading to bone fractures, with deformities and stunted growth in the more severe phenotypes. Other common, nonskeletal findings include blue sclerae and dentinogenesis imperfecta. It is caused mainly by quantitative or structural defects in type I collagen, although dysregulation of different signaling pathways that play a role in bone morphogenesis has been described to be associated with a small fraction of individuals with OI. Recently, a homozygous variant in the translation start site of CCDC134, showing increased activation of the RAS/MAPK signaling pathway, has been reported in three families of Moroccan origin with a severe, deforming form of OI. We report on a 9-year-old Brazilian boy, harboring the same homozygous variant in CCDC134, also presenting severe bone involvement. This report contributes to the phenotypic delineation of this novel autosomal recessive form of OI, which presents with high prevalence of nonunion fractures considered rare events in OI in general. In addition, it expands the phenotype to include base skull anomalies, potentially leading to serious complications, as seen in severe forms of OI. A poor response to bisphosphonate therapy was observed in these individuals. As the variant in CCDC134 leads to dysregulation of the RAS/MAPK signaling pathway, drugs targeted to this pathway could be an alternative to achieve a better management of these individuals.

Biomechanical comparison of multi-rod constructs by satellite rod configurations (in-line vs. lateral) and screw types (monoaxial vs. polyaxial) spanning a lumbar pedicle subtraction osteotomy (PSO): is there an optimal configuration?

PURPOSE: Multi-rod constructs are used commonly to stabilize pedicle subtraction osteotomies (PSO). This study aimed to evaluate biomechanical properties of different satellite rod configurations and effects of screw-type spanning a PSO. METHODS: A validated 3D spinopelvic finite element model with a L3 PSO (30°) was used to evaluate 5 models: (1) Control (T10-pelvis + 2 rods); (2) lateral satellite rods connected via offsets to monoaxial screws (LatSat-Mono) or (3) polyaxial screws (LatSat-Poly); (4) in-line satellite rods connected to monoaxial screws (InSat-Mono) or (4) polyaxial screws (InSat-Poly). Global and PSO range of motions (ROM) were recorded. Rods' von Mises stresses and PSO forces were recorded and the percent differences from Control were calculated. RESULTS: All satellite rods (save InSat-Mono) increased PSO ROM and decreased primary rods' von Mises stresses at the PSO. Lateral rods increased PSO forces (LatSat-Mono:347.1 N; LatSat-Poly:348.6 N; Control:336 N) and had relatively lower stresses, while in-line rods decreased PSO forces (InSat-Mono:280.1 N; InSat-Poly:330.7 N) and had relatively higher stresses. Relative to polyaxial screws, monoaxial screws further decreased PSO ROM, increased satellite rods' stresses, and decreased PSO forces for in-line rods, but did not change PSO forces for lateral rods. CONCLUSION: Multi-rod constructs using in-line and lateral satellite rods across a PSO reduced primary rods' stresses. Subtle differences in biomechanics suggest lateral satellite rods, irrespective of screw type, increase PSO forces and lower rod stresses compared to in-line satellite rods, which had a high degree of posterior instrumentation stress shielding and lower PSO forces. Clinical studies are warranted to determine if these findings influence clinical outcomes.

Influence of double rods and interbody cages on range of motion and rod stress after spinopelvic instrumentation: a finite element study.

PURPOSE: To compare instrumentation configurations consisting of bilateral single or double rods and additional interbody cages (IBCs) at different levels in terms of Range of Motion (ROM) and distribution of von Mises stress in rods. METHODS: A previously validated L1-pelvis finite element model was used and instrumented with configurations consisting of single or double bilateral rods and IBCs at multiple levels. Pure moments of 7.5 N.m were applied to L1 in main directions in addition to a follower load of 280 N. Global, segmental ROM and distribution of von Mises stress in rods were studied. RESULTS: All configurations reduced segmental and global ROM from 50 to 100% compared to the intact spine. Addition of IBCs slightly increased ROM at levels adjacent to the IBC placement. The simple rod configuration presented the highest von Mises stress (457 MPa) in principal rods at L5-S1 in flexion. Doubling rods and IBC placement reduced this value and shifted the location of maximum von Mises stress to other regions. Among studied configurations, double rods with IBCs at all levels (L2-S1) showed the lowest ROM. Maximal von Mises stresses in secondary rods were lower in comparison to main rods. CONCLUSIONS: Double rods and IBCs reduced global and segmental ROM as well as von Mises stress in rods. The results suggest a possible benefit in using both strategies to minimize pseudarthrosis and instrumentation failure. However, increased ROM in adjacent levels and the shift of maximal von Mises stress to adjacent areas might cause complications elsewhere.

Treatment of ankylosing spondylitis complicated with a thoracolumbar Andersson lesion by posterior closed osteotomy, debridement and fusion through the fracture line.

BACKGROUND: An Andersson lesion (AL) is a fatigue fracture occurring across three columns in ankylosing spondylitis (AS), resulting in spinal pseudarthrosis (SP) formation, most commonly in the thoracolumbar segment. However, there is still great controversy and few reports on the best surgical method for the treatment of AS combined with thoracolumbar AL. The purpose of this study was to investigate the efficacy of posterior closed osteotomy, debridement and fusion through the fracture line for the treatment of this disease. METHODS: The clinical data of 13 patients (male 8, female 5, mean age 50.6 years) with AS combined with thoracolumbar AL treated with posterior closed osteotomy, debridement and fusion through the fracture line were retrospectively analysed. The following parameters of the full-length lateral spine radiographs were measured preoperatively and at the last follow-up: cervical 7 tilt (C7T), global kyphosis (GK), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), local kyphosis (LK), angle of the fusion levels (AFL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and sagittal vertical axis (SVA). The visual analog scale (VAS), Oswestry disability index (ODI) and Scoliosis Research Society-22 (SRS-22) scores were recorded preoperatively and at the last follow-up. RESULTS: The mean operation time was 345 min, the mean blood loss was 673 mL, and the mean follow-up time was 21.9 months. Compared with the preoperative values, the C7T, GK, TK, TLK, LK, AFL, PT, SS and SVA values of all patients were significantly improved at the last follow-up (P < 0.05); GK improved from 81.62 ± 16.11 to 50.15 ± 8.55, with an average of 31° of correction (F = 75.945, P<0.001). The VAS, ODI and SRS-22 scores also significantly improved (P < 0.05). At the last follow-up, bone fusion was found in all fracture ends. One patient developed numbness in the lower limbs after surgery and recovered after 3 months of rehabilitation; none of the remaining patients experienced postoperative complications. CONCLUSIONS: Posterior closed osteotomy, debridement and fusion through the fracture line completely removes the necrotic tissue around the SP, relieves symptoms, and corrects kyphosis simultaneously. It reduces the tension behind the fracture line or changes the tension into compressive stress, enabling stable repair of the fracture and avoiding anterior surgery. It is a safe and effective operation.

Endplate-specific fusion rate 1 year after surgery for two-level anterior cervical discectomy and fusion(ACDF).

STUDY DESIGN: This is a retrospective study. OBJECTIVE: Implant nonfusion is an important prognostic factor for patients after anterior cervical discectomy and fusion (ACDF). This study aimed to investigate endplate-specific pseudarthrosis after ACDF, to determine if the rate of fusion is inferior in the lower endplate, and to identify any differences in clinical and radiological results. Research comparing each endplate on which the endplate affects nonfusion is limited. METHODS: We analyzed 71 patients with 142 total spinal levels who underwent double-level ACDF (C4-5-6 and C5-6-7) with an allograft and plate at our hospital between January 2012 and December 2018. Fusion grades were assessed using computed tomography and the Bridwell fusion grade system at 1 year postoperatively. Radiological parameters were obtained from lateral cervical radiographs collected preoperatively and at 1 month and 1 year after surgery. RESULTS: There was no difference in fusion between the C4-5-6 and C5-6-7 ACDF procedures, but the fusion rate and Bridwell fusion grade at the caudal surgery level were lower than those at the cranial surgery level (93 vs. 79%, p < 0.001). The lower endplate of the caudal fusion level showed the most common pseudarthrosis (18 of 71 [25%]). There was no difference in radiological parameters and clinical outcomes between the fusion and pseudarthrosis groups. CONCLUSION: In double-level ACDF procedures, the nonfusion rate was higher at the caudal fusion levels, especially at the lower endplates of the caudal fusion levels.

Functional results after oncological scapula resections.

INTRODUCTION: Tumors of the scapula are rare representing only 1.6%-2.8% of all skeletal tumor localizations. Wide resection of these tumors is often necessary, and their anatomic location is the most decisive factor for the extent of the resection. Because of the importance of the shoulder girdle for all daily activities, such resections can have major functional consequences. However, only few reports with small numbers of cases are found in the literature. PATIENTS AND METHODS: We retrospectively evaluated 31 consecutive patients with scapular tumors treated surgically for aggressive benign or malignant tumors of the scapula. Patients who had received curettage only were excluded. Four of these 31 patients were lost to follow-up. In 7 of the remaining 27 patients, a total scapulectomy had to be performed, whereas all others received a partial resection. In 1 case, a partial resection and replantation after irradiation was performed. Musculoskeletal Tumor Society Scoring System (MSTS) and Toronto Extremity Salvage Score (TESS) scores were evaluated postoperatively at the time of their follow-up. RESULTS: In 16 men and 11 women, the median age was 46.2 years and the tumor entities were heterogeneous. The median follow-up time was 71 months. Three patients died during follow-up due to their tumor and 1 due to cardiac disease. We found significantly better functional results in the group with incomplete scapula resections as opposed to the scapulectomy group. We did not see a significant functional difference between the patients with benign and those with malignant lesions. Both the MSTS score with median 83.3% (range between 23% and 100%) and the TESS score with 81.6% (ranging from 20.4% to 100%) were at a satisfactory level. The preservation of the supraspinatus muscle was shown to be advantageous for better shoulder function, and younger patients also tended to have better postoperative results. CONCLUSION: The resection of scapular tumors may lead to a significant functional disability of the shoulder girdle and the affected arm in many cases. However, this is represented neither in the MSTS or TESS score nor in the overall acceptance of the patients. Only 1 patient, an artisan, had to change his job. In total, the clinical results are quite good in short- and long-term follow-up. The score results were comparable to other studies.

Congenital pseudarthrosis of the clavicle: a systematic review.

PURPOSE: There is no consensus on the type of surgical treatment of congenital pseudarthrosis of the clavicle due to its rarity. The purpose of this study is to provide evidence in favor of a surgical technique and to explore factors correlated with bone consolidation. METHODS: Systematic review of the literature and an analysis of the data for each subject, including all available subjects from the published series and clinical cases since 1990. Fisher's exact tests or T-tests were used to evaluate the effect of independent variables (age at surgery and type of treatment) on bone healing. RESULTS: The literature search provides 305 articles; 30 were selected, reporting 191 patients and 194 clavicles. One hundred and fifty-one clavicles were operated on at a mean age of nine years and four months (from 8 months to 21 years). Thirteen clavicles (8, 6%) had not consolidated at the last follow-up. Concerning the type of fixation, the rate of healing was similar for plates and pins (p = 0.27). The rate of consolidation was higher with autograft than with allograft, xenograft, or no graft (p = 0.00001), and was 100% for vascularized graft. The mean age at surgery was higher for patients who healed at the last follow-up (118 vs. 61 months, p = 0.001). CONCLUSION: In the event of surgical indication for congenital pseudarthrosis of the clavicle, it is recommended to perform autograft and stable fixation (level 4) after seven years old (level 4).