Implant and construct decision-making in metastatic spine tumour surgery: a review of current concepts with a decision-making algorithm.

STUDY DESIGN: Narrative Review. OBJECTIVE: Metastatic spine tumour surgery (MSTS) is an important treatment modality of metastatic spinal disease (MSD). Increase in MSTS has been due to improvements in our oncological treatment, as patients have increased longevity and even those with poorer comorbidities are now being considered for surgery. However, there is currently no guideline on how MSTS surgeons should select the appropriate levels to instrument, and which type of implants should be utilised. METHODS: The current literature on MSTS was reviewed to study implant and construct decision making factors, with a view to write this narrative review. All studies that were related to instrumentation in MSTS were included. RESULTS: A total of 58 studies were included in this review. We discuss novel decision-making models that should be taken into account when planning for surgery in patients undergoing MSTS. These factors include the quality of bone for instrumentation, the extent of the construct required for MSTS patients, the use of cement augmentation and the choice of implant. Various studies have advocated for the use of these modalities and demonstrated better outcomes in MSTS patients when used appropriately. CONCLUSION: We have established a new instrumentation algorithm that should be taken into consideration for patients undergoing MSTS. It serves as an important guide for surgeons treating MSTS, with the continuous evolvement of our treatment capacity in MSD.

A deep learning-based technique for the diagnosis of epidural spinal cord compression on thoracolumbar CT.

PURPOSE: To develop a deep learning (DL) model for epidural spinal cord compression (ESCC) on CT, which will aid earlier ESCC diagnosis for less experienced clinicians. METHODS: We retrospectively collected CT and MRI data from adult patients with suspected ESCC at a tertiary referral institute from 2007 till 2020. A total of 183 patients were used for training/validation of the DL model. A separate test set of 40 patients was used for DL model evaluation and comprised 60 staging CT and matched MRI scans performed with an interval of up to 2 months. DL model performance was compared to eight readers: one musculoskeletal radiologist, two body radiologists, one spine surgeon, and four trainee spine surgeons. Diagnostic performance was evaluated using inter-rater agreement, sensitivity, specificity and AUC. RESULTS: Overall, 3115 axial CT slices were assessed. The DL model showed high kappa of 0.872 for normal, low and high-grade ESCC (trichotomous), which was superior compared to a body radiologist (R4, κ = 0.667) and all four trainee spine surgeons (κ range = 0.625-0.838)(all p < 0.001). In addition, for dichotomous normal versus any grade of ESCC detection, the DL model showed high kappa (κ = 0.879), sensitivity (91.82), specificity (92.01) and AUC (0.919), with the latter AUC superior to all readers (AUC range = 0.732-0.859, all p < 0.001). CONCLUSION: A deep learning model for the objective assessment of ESCC on CT had comparable or superior performance to radiologists and spine surgeons. Earlier diagnosis of ESCC on CT could reduce treatment delays, which are associated with poor outcomes, increased costs, and reduced survival.

AB074. Propensity-score matched analysis to evaluate the safety and utility of intraoperative cell-salvaged autologous blood transfusion in metastatic spine tumour surgery.

BACKGROUND: Blood loss is an important consideration in metastatic spine tumour surgery (MSTS). Allogeneic blood transfusion (ABT) is the current standard of blood replenishment for MSTS despite known complications. Salvaged blood transfusion (SBT) through intraoperative cell salvage addresses the majority of complications related to ABT. However, the use of SBT in MSTS still remains controversial. We aim to conduct a prospective propensity-score (PS) matched analysis to evaluate the long-term clinical outcomes of intraoperative cell salvage (IOCS) in MSTS. METHODS: Our study included 98 patients who underwent MSTS from 2014-2017. A PS matched cohort was created using the relevant and available predictors of treatment assignment and outcomes of interest. Clinical outcomes consisting of overall survival (OS), as well tumour progression (TP) that was evaluated using RECIST (v1.1) were compared in the matched cohort. RESULTS: Our study had a total of 98 patients with a mean age of 60 years old. A total of 33 patients received SBT. Overall median blood loss was 600 mL [interquartile range (IQR): 300-1,000 mL] and overall median blood transfusion (BT) was 620 mL (IQR: 110-1,600 mL). Group PS matching included 30 patients who received ABT and 28 patients who received SBT. There was also no significant difference between the OS of patients who underwent ABT or SBT (P=0.19). SBT did not show any significant increase in 4-year tumour progression [PS matched hazard ratio (HR) 3.659; 95% confidence interval (CI): 0.346-38.7; P=0.28]. CONCLUSIONS: SBT has been shown to have similar clinical outcomes to that of ABT in patients undergoing MSTS, with potential benefits of avoiding complications and costs of ABT. This will be the first long-term PS matched analysis to report on the clinical outcomes of SBT and affirms the clinical role of SBT in MSTS today.

AB075. When would minimally invasive spinal surgery not be preferable for metastatic spine disease?-a narrative review.

BACKGROUND: Metastatic spine tumour surgery (MSTS) is an important treatment modality of metastatic spinal disease (MSD). Open spine surgery (OSS) was previously the gold standard of treatment. However, advancements in MSTS in recent years has resulted in a current paradigm shift towards today's gold standard of minimally invasive spinal surgery (MISS) and early adjuvant RT in treating MSD patients. Nonetheless, there are still certain situations whereby MISS is not desirable or even suitable. There has also yet to be any literature describing the considerations for not using MISS in MSD in today's clinical context. We aim to bridge the gap where OSS should be considered with caution and highlight situations where MISS is preferable using the available literature and personal experience. METHODS: This narrative review was conducted using PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), The Cochrane Library and Scopus databases through August 31, 2023. Inclusion criteria for the review were studies with discussion on the type of surgery in MSTS. RESULTS: A total of 52 studies were included in this review. We discussed various advantages and situations appropriate for MISS for MSD in today's clinical context. Nonetheless, there are still various unique circumstances in which MISS may be less suitable. MISS is less feasible in patients of paediatric profile, having short stature or having had previous surgery at the level of operation. Occipitocervical and cervicothoracic location of vertebrae metastasis also makes MISS less feasible due to access and imaging difficulty. MISS for tumours which are hypersclerotic and hypervascular can also result in more difficulty for cannulation of MISS probes as well as control of bleeding respectively, and hence will be less encouraged in the above settings. CONCLUSIONS: Our review will be the first to discuss circumstances in which MISS is less applicable, despite the advantages it may confer over traditional OSS. MSTS should be individualized to the patient, depending on the experience of the surgeon. OSS is still a time-tested approach that holds weight in MSTS and should be readily utilized depending on the clinical situation.

Does Patient Blood Management Affect Outcomes in Metastatic Spine Tumour Surgery? A Review of Current Concepts.

STUDY DESIGN: Narrative review. OBJECTIVE: The spine is the most common site of metastases, associated with decreased quality of life. Increase in metastatic spine tumour surgery (MSTS) has caused us to focus on the management of blood, as blood loss is a significant morbidity in these patients. However, blood transfusion is also not without its own risks, and hence this led to blood conservation strategies and implementation of a concept of patient blood management (PBM) in clinical practise focusing on these patients. METHODS: A narrative review was conducted and all studies that were related to blood management in metastatic spine disease as well as PBM surrounding this condition were included. RESULTS: A total of 64 studies were included in this review. We discussed a new concept of patient blood management in patients undergoing MSTS, with stratification to pre-operative and intra-operative factors, as well as anaesthesia and surgical considerations. The studies show that PBM and reduction in blood transfusion allows for reduced readmission rates, lower risks associated with blood transfusion, and lower morbidity for patients undergoing MSTS. CONCLUSION: Through this review, we highlight various pre-operative and intra-operative methods in the surgical and anaesthesia domains that can help with PBM. It is an important concept with the significant amount of blood loss expected from MSTS. LEVEL OF EVIDENCE: Not applicable.

Multidirectional instability of the shoulder: a systematic review with a novel classification.

Purpose: A variety of instabilities are grouped under multidirectional instability (MDI) of the shoulder. This makes understanding its diagnostic process, presentation and treatment difficult due to lack of evidence-based consensus. This review aims to propose a novel classification for subtypes of MDI. Methods: A systematic search was performed on PubMed Medline and Embase. A combination of the following 'MeSH' and 'non-MesH' search terms were used: (1) Glenohumeral joint[tiab] OR Glenohumeral[tiab] OR Shoulder[tiab] OR Shoulder joint[tiab] OR Shoulder[MeSH] OR Shoulder joint[MeSH], (2) Multidirectional[tiab], (3) Instability[tiab] OR Joint instability[MeSH]. Sixty-eight publications which met our criteria were included. Results: There was a high degree of heterogeneity in the definition of MDI. Thirty-one studies (46%) included a trauma etiology in the definition, while 23 studies (34%) did not. Twenty-five studies (37%) excluded patients with labral or bony injuries. Only 15 (22%) studies defined MDI as a global instability (instability in all directions), while 28 (41%) studies considered MDI to be instability in two directions, of which one had to include the inferior direction. Six (9%) studies included the presence of global ligamentous laxity as part of the definition. To improve scientific accuracy, the authors propose a novel AB classification which considers traumatic etiology and the presence of hyperlaxity when subdividing MDI. Conclusion: MDI is defined as symptomatic instability of the shoulder joint in two or more directions. A comprehensive classification system that considers predisposing trauma and the presence of hyperlaxity can provide a more precise assessment of the various existing subtypes of MDI. Level of Evidence: III.

AB077. An evaluation of prognostic scoring systems for survival in a surgically treated cohort of 318 metastatic spine tumour surgery patients.

BACKGROUND: Survival prognostication plays a key role in the decision-making process for the surgical treatment of patients with spinal metastases. In the past traditional scoring systems such as the modified Tokuhashi and Tomita scoring systems have been used extensively, however in recent years their accuracy has been called into question. This has led to the development of machine learning algorithms to predict survival. In this study, we aim to compare the accuracy of prognostic scoring systems in a surgically treated cohort of patients. METHODS: This is a retrospective review of 318 surgically treated spinal metastases patients between 2009 and 2021. The primary outcome measured was survival from the time of diagnosis. Predicted survival at 3 months, 6 months and 1 year based on the prognostic scoring system was compared to actual survival. Predictive values of each scoring system were measured via area under receiver operating characteristic curves (AUROC). The following scoring systems were compared, Modified Tokuhashi (MT), Tomita (T), Modified Bauer (MB), Van Den Linden (VDL), Oswestry (O), New England Spinal Metastases score (NESMS), Global Spine Study Tumor Group (GSTSG) and Skeletal Oncology Research Group (SORG) scoring systems. RESULTS: For predicting 3 months survival, the GSTSG 0.980 (0.949-1.0) and NESM 0.980 (0.949-1.0) had outstanding predictive value, while the SORG 0.837 (0.751-0.923) and O 0.837 (0.775-0.900) had excellent predictive value. While for 6 months survival, only the O 0.819 (0.758-0.880) had excellent predictive value and the GSTSG 0.791(0.725-0.857) had acceptable predictive value. For 1 year survival, the NESM 0.871 (0.822-0.919) had excellent predictive value and the O 0.722 (0.657-0.786) had acceptable predictive value. The MT, T and MB scores had an area under the curve (AUC) of <0.5 for 3-month, 6-month and 1-year survival. CONCLUSIONS: Increasingly, traditional scoring systems such as the MT, T and MB scoring systems have become less predictive. While newer scoring systems such as the GSTSG, NESM and SORG have outstanding to excellent predictive value, there is no one survival scoring system that is able to accurately prognosticate survival at all 3 time points. A multidisciplinary, personalised approach to survival prognostication is needed.

AB078. Patterns of treatment delay in patients with symptomatic metastatic epidural spinal cord compression.

BACKGROUND: Delayed treatment in symptomatic metastatic epidural spinal cord compression (MESCC) is significantly associated with poorer functional outcomes. In this study, we aim to identify the patterns of treatment delay in patients and factors predictive of postoperative ambulatory function. METHODS: Retrospective review of patients with symptomatic MESCC treated surgically between January 2015 and January 2022. MESCC symptoms were categorized into symptoms suggesting cord compression requiring immediate referral and symptoms suggestive of spinal metastases. Multivariate analysis was performed to identify factors predictive of postoperative ambulatory function. Delays in treatment were identified and categorized into patient delay (onset of symptoms till initial medical consultation), diagnostic delay (medical consultation till radiological diagnosis of MESCC), referral delay (from diagnosis till spine surgeon review) and surgical delay (from spine surgeon review till surgery) and compared between patients. RESULTS: One hundred and seventy-eight patients were identified. In this cohort 92 (52.0%) patients were able to ambulate independently, and 86 (48.3%) patients were non independent. One hundred and thirty-nine (78.1%) of patients had symptoms of cord compression and 93 (52.3%) had neurological deficits on presentation. On multivariate analysis, pre-operative neurological deficits (P=0.01) and symptoms of cord compression (P=0.01) were significantly associated with post-operative ambulatory function. Mean total delay was 66 days, patient delay was 41 days, diagnostic delay was 16 days, referral delay was 3 days and surgical delay was 6 days. In patients with neurological deficits, there was a significant decrease in all forms of treatment delay (P<0.05). There was no significant decrease in patient delay, diagnostic delay and referral delay in patients with symptoms of cord compression. CONCLUSIONS: Both patients and physicians understand the need for urgent surgical treatment of MESCC with neurological deficits, however there is still a need for increased education and recognition of the symptoms of MESCC.

Vacuum assisted closure and local drug delivery systems in spinal infections: A review of current evidence.

Background: Spinal infections are still showing increased incidence throughout the years as our surgical capabilities increase, coupled with an overall aging population with greater number of chronic comorbidities. The management of spinal infection is of utmost importance, due to high rates of morbidity and mortality, on top of the general difficulty in eradicating spinal infection due to the ease of hematogenous spread in the spine. We aim to summarize the utility of vacuum-assisted closure (VAC) and local drug delivery systems (LDDS) in the management of spinal infections. Methods: A narrative review was conducted. All studies that were related to the use of VAC and LDDS in Spinal Infections were included in the study. Results: A total of 62 studies were included in this review. We discussed the utility of VAC as a tool for the management of wounds requiring secondary closure, as well as how it is increasingly being used after primary closure as prophylaxis for surgical site infections in high-risk wounds of patients undergoing spinal surgery. The role of LDDS in spinal infections was also discussed, with preliminary studies showing good outcomes when patients were treated with various novel LDDS. Conclusions: We have summarized and given our recommendations for the use of VAC and LDDS for spinal infections. A treatment algorithm has also been established, to act as a guide for spine surgeons to follow when tackling various spinal infections in day-to-day clinical practice.

Hip Fracture Management Using External Fixation-A Systematic Review.

INTRODUCTION: Patients with significant comorbidities have high general anaesthetic risks and are often thought to be undesirable candidates for general anaesthesia and, therefore, surgery. External fixation uses local or regional anaesthesia, and allows patients with significant comorbidities to avoid the risks of general anaesthesia. It has been described to be successful in the management of high-risk patients with intertrochanteric fractures. However, published data have been derived from small case series, and no published literature has attempted to analyse them in totality. This review aims to pool together these case series, and to evaluate the outcomes and complications of external fixation when performed in high-risk patients with intertrochanteric fractures. MATERIALS AND METHODS: The review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRSIMA) guidelines. All studies that reported the outcomes of external fixation for intertrochanteric fractures of high-risk patients were included. RESULTS: A total of 13 publications, involving 687 patients, were included in the review. All the studies reported postoperative radiological reduction and complete fracture healing with reduction of limb length discrepancy. One study using parallel placement of proximal fixation screws showed shorter operative duration as compared to convergent placement. Another study mentioned that there was no significant difference in mortality rates between patients with stable fractures and those with unstable fractures who underwent external fixation. All the studies reported a decrease in postoperative immobility, reduction in pain and improvement in clinical outcome hip scores. CONCLUSION: External fixation is promising and useful especially in the management of high-risk patients with intertrochanteric fractures. The procedure can help with radiological reduction of the fracture, reduction of limb length discrepancy, reduction of operative duration, decrease in postoperative immobility, reduction in pain and improvement in clinical outcome hip scores. The procedure is versatile and seems to be able to accommodate both stable and unstable fractures. However, unstable fractures may be associated with greater postoperative morbidity, and it may be worthwhile to prognosticate based on the stability of the patients' fracture for better risk-benefit analysis preoperatively. Shorter operative times can also be achieved through parallel proximal pin placement, without impact on mortality or morbidity.

The Outcomes of Distal Femoral Varus Osteotomy in Patellofemoral Instability: A Systematic Review and Meta-Analysis.

Distal femoral varus osteotomies have been novelly described in the recent years to be successful in the management of patellofemoral instability with genu valgum. However, these publications are limited to case reports and small case series and no published literature have attempted to analyze them in totality. The current review aims to pool together these small case series to evaluate the outcomes and complications of distal varus femoral osteotomies when performed for patellofemoral instability. The review was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. All studies that reported the outcomes of distal femoral varus osteotomy for patellofemoral instability were included. A total of five publications were included in the review, which included a total of 73 patients. All of the studies reported improvement in the radiological outcomes for genu valgum correction and patellofemoral instability. One study using opening wedge osteotomy reported a decrease in Caton-Deschamps index postoperatively, while another study using closing wedge osteotomy reported maintenance of the Caton-Deschamps index postoperatively. Second look arthroscopy showed an improvement in the status of the chondral lesions of the medial facet of the patellar undersurface, the lateral facet of the patellar undersurface and the trochlear groove 2 years postoperatively. All studies also reported a decrease in the risk of recurrence of patellofemoral instability, reduction in pain, and an improvement in all the clinical outcomes knee scores. Distal femoral varus osteotomy is promising and useful in the management of patellofemoral instability with genu valgum. The procedure can allow for radiological correction of the genu valgum and patellofemoral instability, reduction in the risk of recurrence of patellofemoral instability, reduction in pain, improvement in clinical knee outcome scores, and improvement in the status of the chondral lesions in the patellofemoral joint. It is highly versatile and could accommodate varying degrees of correction. These improvements in radiological and clinical outcomes can be seen in studies for both closing wedge and opening wedge distal femoral osteotomies. However, opening wedge osteotomies appear to decrease the patellar height as compared with closing wedge osteotomies which maintain the patellar height; therefore, the patellar height should be assessed preoperatively prior to deciding whether to perform an opening wedge or closing wedge distal femoral varus osteotomy. The Level of Evidence for this study is IV.