Taper Junction Subsidence Occurs in Modular Tumor Endoprostheses: How Concerned Should We Be?

BACKGROUND: Advancements in musculoskeletal oncologic treatment have allowed for longer survival of patients with malignant bone tumors and the associated longer use of tumor endoprostheses in those who have had such reconstructions. Several studies have reported on increased serum metal ions with the use of such implants. Modularity in these implants introduces the risk of taper junction corrosion and subsidence resulting in metal wear particle release that may cause an adverse local tissue reaction or systemic toxicity. Additionally, these implants contain a large surface area of cobalt and chromium. It is unclear whether the source of the increased serum ion levels was due to the taper junction corrosion or the implant itself. To our knowledge, no prior study has reported on taper junction subsidence. QUESTIONS/PURPOSES: In this study we sought (1) to determine survivorship free from radiographic taper junction subsidence in a femoral modular tumor endoprosthesis, and (2) to identify the implant characteristics in the endoprostheses associated with taper subsidence. METHODS: Between January 1996 and February 2020, the senior author performed 150 proximal or distal femur replacements following resections of soft tissue or bone tumors of the thigh and femur. Of those, 6% (9 of 150) of patients were lost to follow-up before 2 years, 25% (37 of 150) could not be analyzed due to absence of plain radiographs during follow-up, and 13% (20 of 150) died before 2 years follow-up, leaving 56% (84 of 150) for analysis in this retrospective study, with a median time for analysis of 14 years (range 2 to 31 years) after the index resection and endoprosthetic reconstruction for patients with distal femur replacements and 5 years (range 2 to 19 years) for patients with proximal femur replacement. Radiographs involving the entire implant were evaluated for the presence or absence of subsidence of the taper junction that was evident and clear to see if present. The association between the number of taper junctions, the length of resection, the number of collapsed junctions, and the time to collapse from the initial surgery were examined using regression analysis. RESULTS: Overall, 14% (12 of 84) patients with a distal femur replacement had radiographic collapse of at least one of the modular tapers. Survivorship free from taper subsidence was 91% (95% CI 86% to 96%) at 10 years and 84% (95% CI 78% to 90%) at 20 years. All patients were in the distal femur replacement group. The median follow-up of patients with subsidence was 15 years (range 5 to 26). Fifty-eight percent (7 of 12) of patients had two junctions involved, 25% (3 of 12) had three junctions, and 17% (2 of 12) had one junction involved. All but one patient had subsidence in a single junction. The median time to subsidence was 15 years (range 4.5 to 24.0 years). The subsidence was progressive in all patients who demonstrated it. The taper junction subsidence was complete in 75% (9 of 12) of patients and partial in 25% (3 of 12). Univariate and multivariable regression analyses did not show that the risk factors we studied were associated with subsidence. Two patients with junction subsidence were revised, one for taper fracture and one during busing exchange for distal junction subsidence. CONCLUSION: Taper damage with late and progressive subsidence of the intervening junction is not uncommon after distal femur replacement. The impact of such a complication is still unknown. Further studies should examine the long-term outcomes and correlate them with metal ion levels. LEVEL OF EVIDENCE: Level III, therapeutic study.

Development of Machine Learning Models for Predicting the 1-Year Risk of Reoperation After Lower Limb Oncological Resection and Endoprosthetic Reconstruction Based on Data From the PARITY Trial.

BACKGROUND: Oncological resection and reconstruction involving the lower extremities commonly lead to reoperations that impact patient outcomes and healthcare resources. This study aimed to develop a machine learning (ML) model to predict this reoperation risk. METHODS: This study was conducted according to TRIPOD + AI. Data from the PARITY trial was used to develop ML models to predict the 1-year reoperation risk following lower extremity oncological resection and reconstruction. Six ML algorithms were tuned and calibrated based on fivefold cross-validation. The best-performing model was identified using classification and calibration metrics. RESULTS: The polynomial support vector machine (SVM) model was chosen as the best-performing model. During internal validation, the SVM exhibited an AUC-ROC of 0.73 and a Brier score of 0.17. Using an optimal threshold that balances all quadrants of the confusion matrix, the SVM exhibited a sensitivity of 0.45 and a specificity of 0.81. Using a high-sensitivity threshold, the SVM exhibited a sensitivity of 0.68 and a specificity of 0.68. Total operative time was the most important feature for reoperation risk prediction. CONCLUSION: The models may facilitate reoperation risk stratification, allowing for better patient counseling and for physicians to implement measures that reduce surgical risks.

A multimodal neural network with gradient blending improves predictions of survival and metastasis in sarcoma.

The objective of this study is to develop a multimodal neural network (MMNN) model that analyzes clinical variables and MRI images of a soft tissue sarcoma (STS) patient, to predict overall survival and risk of distant metastases. We compare the performance of this MMNN to models based on clinical variables alone, radiomics models, and an unimodal neural network. We include patients aged 18 or older with biopsy-proven STS who underwent primary resection between January 1st, 2005, and December 31st, 2020 with complete outcome data and a pre-treatment MRI with both a T1 post-contrast sequence and a T2 fat-sat sequence available. A total of 9380 MRI slices containing sarcomas from 287 patients are available. Our MMNN accepts the entire 3D sarcoma volume from T1 and T2 MRIs and clinical variables. Gradient blending allows the clinical and image sub-networks to optimally converge without overfitting. Heat maps were generated to visualize the salient image features. Our MMNN outperformed all other models in predicting overall survival and the risk of distant metastases. The C-Index of our MMNN for overall survival is 0.77 and the C-Index for risk of distant metastases is 0.70. The provided heat maps demonstrate areas of sarcomas deemed most salient for predictions. Our multimodal neural network with gradient blending improves predictions of overall survival and risk of distant metastases in patients with soft tissue sarcoma. Future work enabling accurate subtype-specific predictions will likely utilize similar end-to-end multimodal neural network architecture and require prospective curation of high-quality data, the inclusion of genomic data, and the involvement of multiple centers through federated learning.

Comparative Outcomes and Failure Rates of Total Femur Replacement in Oncologic and Nononcologic Indications: A Systematic Review and Meta-analysis.

BACKGROUND: Total femur replacement (TFR) has become increasingly significant as a salvage procedure for both oncologic reconstruction and complex nononcologic conditions such as revision arthroplasty. Despite its effectiveness in limb salvage, TFR is associated with high complication and failure rates, which vary depending on the underlying indication. METHODS: This systematic review and meta-analysis adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of MEDLINE, EMBASE, Web of Science, and Cumulative Index to Nursing and Allied Health Literature databases was conducted, focusing on studies that reported outcomes of TFR in oncologic and nononcologic cases. Primary outcomes included failure mode and rates according to the Henderson classification, functional outcomes scores, and mobility status. Data were analyzed using random-effects models and generalized linear mixed models. RESULTS: A total of 35 studies involving 1,002 patients were included. The majority of TFRs were performed for oncologic reasons (63.7%). The mean Musculoskeletal Tumor Society (MSTS) score was 66%, with a limb salvage rate of 89%. The meta-analysis revealed a combined failure rate of 34%. For type 4 failures (infection), nononcologic patients exhibited a significantly higher rate at 18% (95% confidence interval [CI], 12%-26%, I2 = 46%, p < 0.01) compared with 8% in oncologic patients (95% CI, 6%-12%, I2 = 0%). Regarding combined types 1 to 4 failures, oncologic patients had a rate of 20% (95% CI, 25%-52%, I2 = 60%), whereas nononcologic patients faced a higher rate of 37% (95% CI, 12%-26%, I2 = 63%) (p < 0.05), indicating a significant difference. There were no significant differences in the MSTS score. In addition, there were no notable differences when comparing failure modes 1, 2, and 3 independently. Mobility analysis showed that approximately 70% of patients required walking aids after surgery. CONCLUSION: TFR offers a valuable limb salvage option in both oncologic and nononcologic scenarios, despite its high failure rates. Although functional outcomes were similar between groups, the higher failure rate in nononcologic cases and the poor overall quality of evidence warrant further comprehensive assessments into predictors of outcomes to optimize results. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.

Bone Allograft Pedicle Screw Augmentation: A Biomechanical Study.

STUDY DESIGN: We performed a comprehensive cadaveric biomechanical study to compare the fixation strength of primary screws, screws augmented with bone allograft, and screws augmented with polymethylmethacrylate cement. OBJECTIVE: To evaluate a novel technique for screw augmentation using morselized cortico-cancellous bone allograft to fill the widened screw track of failed pedicle screws. BACKGROUND: To date, there are no known biological methods available for failed pedicle screw augmentation or fixation. MATERIALS AND METHODS: Biomechanical tests were performed using 2 different testing modalities to quantify fixation strength including axial screw pullout and progressive cyclic displacement tests. RESULTS: Fifty vertebrae were instrumented with pedicle screws. Our study showed that bone allograft augmentation using the same diameter screw was noninferior to the fixation strength of the initial screw. In the axial pullout test, screws undergoing bone allograft repair failed at 25% lower loads compared with native screws, and screws augmented with cement showed approximately twice as much strength compared with native screws. In the cyclic displacement test, screws fixed with cement resisted loosening the best of all the groups tested. However, screws augmented with bone graft were found to have an equal strength to native screw purchase. our study did not find a correlation with bone mineral density as a predictor for failure in axial pullout or cyclic displacement tests. CONCLUSION: Bone allograft augmentation for pedicle screw fixation was noninferior to the initial screw purchase in this biomechanical study. This bone allograft technique is a viable option for screw fixation in the revision setting when there is significant bone loss in the screw track.

Controversies in orthopaedic oncology.

Chondrosarcoma is the second most common surgically treated primary bone sarcoma. Despite a large number of scientific papers in the literature, there is still significant controversy about diagnostics, treatment of the primary tumour, subtypes, and complications. Therefore, consensus on its day-to-day treatment decisions is needed. In January 2024, the Birmingham Orthopaedic Oncology Meeting (BOOM) attempted to gain global consensus from 300 delegates from over 50 countries. The meeting focused on these critical areas and aimed to generate consensus statements based on evidence amalgamation and expert opinion from diverse geographical regions. In parallel, periprosthetic joint infection (PJI) in oncological reconstructions poses unique challenges due to factors such as adjuvant treatments, large exposures, and the complexity of surgery. The meeting debated two-stage revisions, antibiotic prophylaxis, managing acute PJI in patients undergoing chemotherapy, and defining the best strategies for wound management and allograft reconstruction. The objectives of the meeting extended beyond resolving immediate controversies. It sought to foster global collaboration among specialists attending the meeting, and to encourage future research projects to address unsolved dilemmas. By highlighting areas of disagreement and promoting collaborative research endeavours, this initiative aims to enhance treatment standards and potentially improve outcomes for patients globally. This paper sets out some of the controversies and questions that were debated in the meeting.

The Impact of Adjunct Medical Therapy on Survival after Spine Metastasis: A Systematic Review and Pooled Data Analysis.

Targeted therapy has greatly improved the outlook for patients with spinal metastatic cancers. Scoring systems like the Tokuhashi or Tomita scores are commonly used to predict prognosis and inform surgical decisions, but they are outdated and fail to consider recent advancements. We aimed to investigate the current state of the literature and treatment options pertaining to advancements in targeted therapy compared to other forms of medical management for metastatic spinal tumors. This study represents the first comprehensive systematic review that encompasses the most common primary cancers that metastasize to the spine and evaluates the median overall survival (mOS) across five different medical treatment modalities as well as surgical intervention. Additionally, our study analyzes the tumor receptor status in conjunction with these treatments. A PubMed search was conducted, and according to the PRISMA guidelines, 28 articles out of 1834 met the inclusion criteria. The pooled data analysis highlighted the superior efficacy of targeted therapy, evidenced by a significant improvement in the mOS and lower hazard ratios in patients with lung and breast cancers who received targeted therapy compared to those who did not. Our study provides valuable insights into the recent advancements in the medical management of metastatic spinal tumors. Future indications include incorporating this literature into personalized treatment approaches for metastatic spinal tumors.

Does Spinal Cord Type Predict Intraoperative Neuro-Monitoring Alerts in Scoliosis Correction Surgery? A Systematic Review and Meta-Analysis of Operative and Radiologic Predictors.

STUDY DESIGN: Systematic literature review and meta-analysis. OBJECTIVES: Predicting patient risk of intraoperative neuromonitoring (IONM) alerts preoperatively can aid patient counselling and surgical planning. Sielatycki et al established an axial-MRI-based spinal cord classification system to predict risk of IONM alerts in scoliosis correction surgery. We aim to systematically review the literature on operative and radiologic factors associated with IONM alerts, including a novel spinal cord classification. METHODS: A systematic review and meta-analysis was performed as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Guidelines. A literature search identifying all observational studies comparing patients with and without IONM alerts was conducted. Suitable studies were included. Patient demographics, radiological measures and operative factors were collected. RESULTS: 11 studies were included including 3040 patients. Relative to type 3 cords, type 1 (OR = .03, CI = .01-.08, P < .00001), type 2 (OR = .08, CI = .03, P <.00001) and all non-type 3 cords (OR = .05, CI = .02-.16, P < .00001) were associated with significantly lower odds of IONM alerts. Significant radiographic measures for IONM alerts included coronal Cobb angle (MD = 10.66, CI = 5.77-15.56, P < .00001), sagittal Cobb angle (MD = 9.27, CI = 3.28-14.73, P = .0009), sagittal deformity angle ratio (SDAR) (MD = 2.76, CI = 1.57-3.96, P < .00001) and total deformity angle ratio (TDAR) (MD = 3.44, CI = 2.27-4.462, P < .00001). Clinically, estimated blood loss (MD = 274.13, CI = -240.03-788.28, P = .30), operation duration (MD = 50.79, CI = 20.58-81.00, P = .0010), number of levels fused (MD = .92, CI = .43-1.41, P = .0002) and number of vertebral levels resected (MD = .43, CI = .01-.84, P = .05) were significantly greater in IONM alert patients. CONCLUSIONS: This study highlights the relationship of operative and radiologic factors with IONM alerts.

Giant cell tumour of bone.

Giant cell tumour of bone (GCTB) is a locally aggressive lesion that is difficult to treat as salvaging the joint can be associated with a high rate of local recurrence (LR). We evaluated the risk factors for tumour relapse after treatment of a GCTB of the limbs. A total of 354 consecutive patients with a GCTB underwent joint salvage by curettage and reconstruction with bone graft and/or cement or en bloc resection. Patient, tumour, and treatment factors were analyzed for their impact on LR. Patients treated with denosumab were excluded. There were 53 LRs (15%) at a mean 30.5 months (5 to 116). LR was higher after curettage (18.4%) than after resection (4.6%; p = 0.008). Neither pathological fracture (p = 0.240), Campanacci grade (p = 0.734), soft-tissue extension (p = 0.297), or tumour size (p = 0.872) affected the risk of recurrence. Joint salvage was possible in 74% of patients overall (262/354), and 98% after curettage alone (262/267). Of 49 patients with LR after curettage, 44 (90%) underwent repeated curettage and joint salvage. For patients treated by curettage, only age less than 30 years (p = 0.042) and location in the distal radius (p = 0.043) predicted higher LR. The rate of LR did not differ whether cement or bone graft was used (p = 0.753), but may have been reduced by the use of hydrogen peroxide (p = 0.069). Complications occurred in 15.3% of cases (54/354) and did not differ by treatment. Most patients with a GCTB can undergo successful joint salvage by aggressive curettage, even in the presence of a soft-tissue mass, pathological fracture, or a large lesion, with an 18.4% risk of local recurrence. However, 90% of local relapses after curettage can be treated by repeat joint salvage. Maximizing joint salvage is important to optimize long-term function since most patients with a GCTB are young adults. Younger patients and those with distal radius tumours treated with joint-sparing procedures have a higher rate of local relapse and may require more aggressive treatment and closer follow-up.

Value of Cellular Components and Focal Dedifferentiation to Predict the Risk of Metastasis in a Benign-Appearing Extra-Meningeal Solitary Fibrous Tumor: An Original Series from a Tertiary Sarcoma Center.

Histology has not been accepted as a valid predictor of the biological behavior of extra-meningeal solitary fibrous tumors (SFTs). Based on the lack of a histologic grading system, a risk stratification model is accepted by the WHO to predict the risk of metastasis; however, the model shows some limitations to predict the aggressive behavior of a low-risk/benign-appearing tumor. We conducted a retrospective study based on medical records of 51 primary extra-meningeal SFT patients treated surgically with a median follow-up of 60 months. Tumor size (p = 0.001), mitotic activity (p = 0.003), and cellular variants (p = 0.001) were statistically associated with the development of distant metastases. In cox regression analysis for metastasis outcome, a one-centimeter increment in tumor size enhanced the expected metastasis hazard by 21% during the follow-up time (HR = 1.21, CI 95% (1.08-1.35)), and each increase in the number of mitotic figures escalated the expected hazard of metastasis by 20% (HR = 1.2, CI 95% (1.06-1.34)). Recurrent SFTs presented with higher mitotic activity and increased the likelihood of distant metastasis (p = 0.003, HR = 12.68, CI 95% (2.31-69.5)). All SFTs with focal dedifferentiation developed metastases during follow-up. Our findings also revealed that assembling risk models based on a diagnostic biopsy underestimated the probability of developing metastasis in extra-meningeal SFTs.

Primary Sarcomas of the Spine: A Systematic Review and Pooled Data Analysis.

STUDY DESIGN: A systematic review of the literature and pooled data analysis of treatment outcomes of primary sarcomas of the spine. OBJECTIVE: To examine the current literature and treatment options for primary sarcomas of the spine. SUMMARY OF BACKGROUND DATA: A paucity of literature exists on treatment outcomes of primary sarcomas of the spine. MATERIALS AND METHODS: Two authors searched PubMed to identify articles for review, and a pooled data analysis was performed to determine overall survival for each type of surgical resection on spine sarcomas. RESULTS: In total, 1776 articles were identified, and 11 met our inclusion criteria for review. In chondrosarcoma, overall survival was significantly higher with en bloc excision when compared with piecemeal resection (HR for piecemeal resection: 4.11; 95% CI: 2.08-8.15). Subgroup analysis showed that the addition of radiation therapy after piecemeal excision increased overall survival to 60 months from 48 months with piecemeal excision alone. In osteosarcoma, there was no significant difference in overall survival between en bloc and piecemeal resection (HR for piecemeal resection: 1.76; 95% CI: 0.776-3.99). In Ewing's sarcoma, overall survival was significantly higher when a successful en bloc resection was achieved and coupled with chemotherapy and radiation therapy for local control (HR for piecemeal resection: 7.96; 95% CI: 2.12-20.1). Interestingly, when a successful en bloc resection could not be achieved, chemotherapy and radiation therapy alone had significantly higher survival than piecemeal resection (HR for piecemeal resection: 2.63; 95% CI: 1.01-6.84). A significantly higher number of local recurrences were associated with the piecemeal resection group in all types of spine sarcomas. CONCLUSION: This review and pooled data seem to favor en bloc excision for local control as the treatment of choice in primary sarcomas of the spine.

Surgical Management of the Metastatic Spine Disease: A Review of the Literature and Proposed Algorithm.

STUDY DESIGN: Narrative Review. The spine remains the most common site for bony metastasis. It is estimated that up to 70% of cancer patients harbor secondary spinal disease. And up to 10% will develop a clinically significant lesion. The last two decades have seen a substantial leap forward in the advancements of the management of spinal metastases. What once was a death sentence is now a manageable, even potentially treatable condition. With marked advancements in the surgical treatment and post-operative radiotherapy, a standardized approach to stratify and manage these patients is both prudent and now feasible. OBJECTIVES: This article looks to examine the best available evidence in the stratification and surgical management of patients with spinal metastases. So the aim of this review is to offer a standardized approach for surgical management and surgical planning of patients with spinal metastases.

Outcomes After Abductor Reattachment to Proximal Femur Endoprosthesis After Tumor Resection.

INTRODUCTION: Resection of the proximal femur raises several challenges including restoration of the abductor mechanism. Few evaluated the outcomes of different techniques of abductor fixation to the proximal femur endoprosthesis. METHODS: A retrospective review of patients who underwent proximal femoral arthroplasty with a minimum follow-up of 12 months was conducted. Patients were divided into two groups: (1) those with preserved greater trochanter (GT) reattached to the implant and (2) those with direct abductor muscle reattachment. Both groups were compared for surgical and functional outcomes. Group 1 patients were subdivided into those who received GT reinsertion using grip and cables and those reattached using sutures. RESULTS: Fifty-three patients were included with a mean follow-up of 49 months. There were 22 patients with reinserted GT and 31 patients with soft-tissue repair. The endoprosthesis revision rate was comparable between groups (P = 0.27); however, the incidence of dislocations was higher in group 2 (0/22 versus 6/31; P = 0.035). Trendelenburg gait (77% versus 74%), use of walking aids (68% versus 81%), and abductor muscle strength were comparable between both groups (P > 0.05). In group 1, 15 patients had GT reinsertion with grip and cables. Of those, five patients (33%) had cable rupture within 13 months of follow-up. GT displacement reached 12 mm at 12 months of follow-up in patients with grip and cables compared with 26 mm in patients with GT suture reinsertion (P < 0.05). DISCUSSION: Although GT preservation did not improve functional outcomes, it was associated with a lower dislocation rate despite frequent cable failure. Less displacement was observed when GT reattachment used grip and cables.

Intermuscular extremity myxoid liposarcoma can be managed by marginal resection following neoadjuvant radiotherapy.

BACKGROUND: Compared with other soft tissue sarcomas, myxoid liposarcoma (MLS) occurs in younger patients, has a propensity for intermuscular locations and is highly radiosensitive. With pre-operative radiotherapy, intermuscular MLS demonstrates substantial volume reduction and can be easily separated from surrounding tissues during resection. However, it is unclear whether marginal excision of MLS is oncologically safe. This study aimed to assess the association between margins and survival in irradiated, intermuscular MLS. METHODS: The study identified 198 patients from seven sarcoma centres with a first presentation of localized, extremity, intermuscular MLS that received pre-operative radiotherapy and was diagnosed between 1990 and 2017. Patient and treatment characteristics, radiological and histological responses to neoadjuvant treatment and clinical surveillance were recorded. RESULTS: Margins were microscopically positive in 11% (n = 22), <1.0 mm in 15% (n = 29) and ≥1.0 mm in 72% (n = 143). There was no association between margin status and local recurrence-free, metastasis-free or overall survival. This finding held true even in patients at higher risk of worse overall survival based on multivariable analysis (% round cell≥5%, percentage ellipsoid tumour volume change ≤ -60.1%). CONCLUSION: Irradiated, extremity, intermuscular myxoid liposarcoma can safely undergo marginal resection without compromising oncologic control.

Joint-sparing reconstruction for extensive periacetabular metastases: Literature review and a novel minimally invasive surgical technique.

Classically, patients with advanced lytic disease of the acetabulum secondary to metastatic bone disease are treated with complex arthroplasty reconstruction techniques. Advancements in percutaneous techniques have extended the indications for safer, minimally invasive procedures for patients with periacetabular metastasis without the need for complex hip replacement and the complications that follow it. The purpose of this report is to revisit the management of this group of patients and provide indications for an alternative minimally invasive joint-sparing technique. We describe a novel technique using a combination of percutaneous cryoablation, cementoplasty and two-screw fixation. With careful consideration of indications, excellent functional and oncologic outcomes one year after surgery is possible without the need for additional procedures.

Development and model form assessment of an automatic subject-specific vertebra reconstruction method.

BACKGROUND: Current spine models for analog bench models, surgical navigation and training platforms are conventionally based on 3D models from anatomical human body polygon database or from time-consuming manual-labelled data. This work proposed a workflow of quick and accurate subject-specific vertebra reconstruction method and quantified the reconstructed model accuracy and model form errors. METHODS: Four different neural networks were customized for vertebra segmentation. To validate the workflow in clinical applications, an excised human lumbar vertebra was scanned via CT and reconstructed into 3D CAD models using four refined networks. A reverse engineering solution was proposed to obtain the high-precision geometry of the excised vertebra as gold standard. The 3D model evaluation metrics and a finite element analysis (FEA) method were designed to reflect the model accuracy and model form errors. RESULTS: The automatic segmentation networks achieved the best Dice score of 94.20% in validation datasets. The accuracy of reconstructed models was quantified with the best 3D Dice index of 92.80%, 3D IoU of 86.56%, Hausdorff distance of 1.60 mm, and the heatmaps and histograms were used for error visualization. The FEA results showed the impact of different geometries and reflected partial surface accuracy of the reconstructed vertebra under biomechanical loads with the closest percentage error of 4.2710% compared to the gold standard model. CONCLUSIONS: In this work, a workflow of automatic subject-specific vertebra reconstruction method was proposed while the errors in geometry and FEA were quantified. Such errors should be considered when leveraging subject-specific modelling towards the development and improvement of treatments.

Mechanical Complications in Adult Spinal Deformity Surgery: Can Spinal Alignment Explain Everything?

STUDY DESIGN: Cohort study. OBJECTIVE: Our goal was to verify the validity of the global alignment and proportion (GAP) score, SRS-Schwab, and Roussouly theoretical apex of lordosis in predicting mechanical complications in adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Achieving adequate sagittal alignment is critical to obtain favorable outcomes in ASD surgery. It has been proposed that mechanical complications are largely secondary to postoperative spinal alignment. METHODS: Retrospective review of consecutive primary ASD cases that underwent deformity correction in the same institution over a 5-year period. Association between the 6-week postoperative spinal alignment classification and occurrence of mechanical complications on the last follow-up was assessed using logistic regressions. The discriminant capacity was assessed using the receiver operating characteristic (ROC) curve analysis. RESULTS: 58.3% (N = 49/84) of patients presented with mechanical complications and 32.1% (N = 27/84) underwent revision surgery. GAP score did not show discriminant ability to predict complications (AUC = 0.53, 95% confidence interval [CI] = 0.40-0.66, P = 0.58). Conversely, the SRS-Schwab sagittal modifier score demonstrated a statistically significant (although modest) predictive value for mechanical complications (AUC = 0.67, 95% CI = 0.54-0.79, P = 0.008). There was a significant association between pelvic tilt (PT) (P = 0.03) and sagittal vertical axis (SVA) (P = 0.01) at 6 weeks postoperatively and the occurrence of later mechanical complications. There was no significant association between matched Roussouly theoretical apex of lordosis and final outcome (P = 0.47). CONCLUSION: The results point to the complexity of mechanical failure and the high likelihood that causative factors are multifactorial and not limited to alignment measures. GAP score should be used with caution as it may not explain or predict mechanical failure based on alignment in all populations as originally expected. Future studies should focus on etiology, surgical technique, and patient factors in order to generate a more universal score that can be applied to all populations.Level of Evidence: 4.

Skeletal regeneration for segmental bone loss: Vascularised grafts, analogues and surrogates.

Massive segmental bone defects (SBD) are mostly treated by removing the fibula and transplanting it complete with blood supply. While revolutionary 50 years ago, this remains the standard treatment. This review considers different strategies to repair SBD and emerging potential replacements for this highly invasive procedure. Prior to the technical breakthrough of microsurgery, researchers in the 1960s and 1970s had begun to make considerable progress in developing non autologous routes to repairing SBD. While the breaktthrough of vascularised bone transplantation solved the immediate problem of a lack of reliable repair strategies, much of their prior work is still relevant today. We challenge the assumption that mimicry is necessary or likely to be successful and instead point to the utility of quite crude (from a materials technology perspective), approaches. Together there are quite compelling indications that the body can regenerate entire bone segments with few or no exogenous factors. This is important, as there is a limit to how expensive a bone repair can be and still be widely available to all patients since cost restraints within healthcare systems are not likely to diminish in the near future. STATEMENT OF SIGNIFICANCE: This review is significant because it is a multidisciplinary view of several surgeons and scientists as to what is driving improvement in segmental bone defect repair, why many approaches to date have not succeeded and why some quite basic approaches can be as effective as they are. While there are many reviews of the literature of grafting and bone repair the relative lack of substantial improvement and slow rate of progress in clinical translation is often overlooked and we seek to challenge the reader to consider the issue more broadly.

A Comparison of Patient and Surgeon Expectations of Spine Surgical Outcomes.

STUDY DESIGN: Ambispective cohort study. OBJECTIVE: Limited data exists comparing surgeon and patient expectations of outcome following spine surgery. The objective of this study was to elicit whether any differences exist between patient and surgeon expectations for common spine surgeries. METHODS: Ten common age-appropriate clinical scenarios were generated and sent to Canadian spine surgeons to determine surgeon expectations for standard spine surgeries. Patients in the Canadian Spine Outcomes and Research Network (CSORN) registry matching the clinical scenarios were identified. Aggregated patient expectations were compared with surgeon responses for each scenario. A χ2 analysis was then completed to determine discrepancies between surgeon and patient expectations for each scenario. RESULTS: A total of 51 Canadian spine surgeons completed the survey on surgical expectations. A total of 919 patients from multiple centers were identified within the CSORN database that matched the clinical scenarios. Our results demonstrated that patients tend to be more optimistic about the expected outcomes of surgery compared with the treating surgeon. The majority of patients in all clinical scenarios anticipated improvement in back or neck pain after surgery, which differed from surgeon expectations. Results also highlighted the effect of patient age on both patient and surgeon expectations. Discrepancies between patient and surgeon expectations were higher for older patients. CONCLUSION: We present data on patient and surgeon expectations for spine surgeries and show that differences exist particularly concerning the improvement of neck or back pain. Patient age plays a role in the agreement between the treating physicians and patients in regard to surgical expectations. The reasons for the discrepancies remain unclear.

Primary sarcomas of the spine: population-based demographic and survival data in 107 spinal sarcomas over a 23-year period in Ontario, Canada.

BACKGROUND CONTEXT: Spinal sarcomas are a rare, heterogeneous group of mesenchymal tumors. Current literature reporting demographic variables and survival information is limited to small case series, and a single registry with variable treatment modalities and time periods. PURPOSE: We report on population-level data regarding all spinal sarcomas diagnosed over a 23-year period in Ontario, Canada, for the purposes of calculating incidence and prevalence of these tumors. Secondarily, survival is assessed by tumor type as well as adjuvant therapies during this time period. STUDY DESIGN: Retrospective Cohort Study PATIENT SAMPLE: Population-based data from the Institute for Clinical Evaluative Sciences (ICES) between 1993 and 2015. OUTCOME MEASURES: Outcome measures include incidence and prevalence of spinal osteosarcoma, Ewing's sarcoma, and chondrosarcoma of the spine, as well as 2-, 5-, 10- and 15-year survival and prevalence of adjuvant therapies. METHODS: Utilizing population-based data from the Institute for Clinical Evaluative Sciences (ICES) between 1993 and 2015, ICD codes were searched and available data extracted for the purposes of reporting basic demographic information and calculation of Kaplan Meyer survival curves. Databases include the Ontario Cancer Registry, Discharge Abstract Database, Ontario Health Insurance Plan, National Ambulatory Care Reporting System, Registered Persons DataBase (death) were analyzed. RESULTS: One hundred and seven spinal sarcomas were identified, with a mean incidence was 0.38 sarcomas per million population per year, that was stable over time. The mean prevalence was 8.1 sarcomas per million population. The most common diagnosis was Ewing's sarcoma (48 [44.9%] patients), followed by chondrosarcoma (33 [30.8%] patients), and osteosarcoma (26 [24.3%] patients). Chondrosarcoma had the highest survival rates with 77.2% and 64.2% 5- and 10-year survival rates, respectively, followed by Ewing's sarcoma with 48.1% and 44.9% 5 and 10-year survival and osteosarcoma with 36.0% and 30.9% 5- and 10-year survival. CONCLUSIONS: Spinal sarcoma is a rare disease with variable survival depending on the histologic diagnosis. This population-level study involves a heterogeneous group of patients with variable stages of disease at presentation and variable treatments. Our data fit with the published literature for survival for those treated conservatively and surgically. Our data show considerable improvement in 5- and 10-year mortality when compared with previous population level studies on earlier patient cohorts, likely reflecting improvements in systemic and surgical treatments.